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10-12-2006 Post mapped to one branch of Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 1
Post ID: 2941
Reply to: 2941
Initial thoughts about new/old Lamm ML2s

I have recently acquired a pair of (2000 vintage, I think) Lamm ML2s and would like to share impressions and development strategies with other ML2 owners, including former owners, and perhaps I may learn from any pertinent experience.

In addition to changing amps, from Wright-Sound WPA3.5 2A3 SETs to the Lamms, I have just moved into a new (to me) house with 8’ ceilings instead of the sloping (10 - 20’) ceilings at my former residence. The ”new” listening room is  on a wood-framed floor while the old one was on a slab.  Also, while I had pretty much solved my grounding problems at the old place (3/4” copper rod driven just outside the system wall, for phono), I am just getting into this again here and now.  In other words, my recent audition of the ML2s was compromised, to say the least.  But, still, I got some impressions from the ML2s.

I had finally reached the point where I had done about all I could with the Wrights.  I had gotten the room pretty well pressurized, etc., but I was growing annoyed and disappointed with the limited frequency range and dynamics, and so I began looking around to see what I could find as a next step.

And so, under these clouds and with highest hopes, the Lamm ML2s entered the picture.

I am pretty sure the amps could do with new tubes, but here goes with 1st impressions, with CD source instead of my usual phono:

For one thing, the amps did everything better and better as time passed, up to the 1 hour mark, when I ended the session.  From the first the amps did not sound like the coveted straight-wire-with-gain, but rather they seem to somehow rearrange the mosh they are fed and turn it into a more realistic musical sound.  I suspect some sort of feedback is involved in this, and maybe even some mysterious form of group/phase delay, although there was no overt trace of echo effects or smearing, at all, which might cause me to suspect this.

But the thing these amps did the best during my first, compromised session was the way they create an artfully correct(ed) version of time and space, in which the musical notes and pressures assumed their correct-as-in-living-music attitudes and relationships.  There is roughness when appropriate, which is very rare, and overall sounds happen just about the way they should, neither forced nor held back by the ML2s

And the background to all the sound was not “black” but simply the part that is not music, just as one finds with live music, which effect so charms me that I am excited about hearing it again.

Something I have observed with solid state versus tubes in general, and SETs in particular, is that notes through SS amps seem to implode, while notes though tubes seem to explode.  And now that I think back, I am not sure that notes from the Lamms do either.

One sound I remember well as a reference is that of a band playing outdoors, where the sound almost seems to contradict itself if one tries to describe it, the way it is at once ragged and smooth, so immediate and vital, yet it just dies away so quickly it’s as if it went into a vacuum.  Likewise, the frequency range is all there, obviously, yet where are the “highs” or “lows” the audiophile craves?  I think I want to hear some marching band music through the ML2s.

I should also mention that the “sound stage” was plenty “deep” and “wide” from the get go, but it was oddly short in terms of height, and it “grew” in height over the one hour session.  The “space” the amps put the music in is more about music than space, which I like, but the space is “there”, and it sounded/felt as if it just went on  and on like the rest of the world; very odd.

My own sonic priorities are pitch, timbre weight and scale of acoustic instruments and voices; then dynamics; then immediacy; then sound effects (soundstage, etc.); then “details”, which I simply cannot abide out of proportion.  I actually like all these things, but if the first things are wrong, I cannot sustain interest for long.

The ML2s started out with some SS congestion but cleared up considerably by the end of my first session.  I did not get good bass or proper lower-mid weight, but this is so room/speaker dependent that I don’t think it’s worth discussing at this point.  I found myself pulling my speakers farther and farther out into the room, off the short wall, and I may eventually try them along the long wall, firing across the short axis of the living/listening room and into the dining room.  I certainly have not gotten the room pressure level right yet.

Best regards,
Paul S
10-12-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 2
Post ID: 2942
Reply to: 2941
Let you Lamm ML2 to burn for a while.
Generally, the ML2 sounds fine after >45 minutes of running, pretty much as any other tube amp. Also since your Lamms were sitting for 5 years without working you would need a few weeks unit your Lamms reach a nominal operation condition. The well “trained” ML2 sounds very grainy for the first 15 minutes and too rigid for the next 15 minutes.  It should relax after 30 minutes and does very well after one hour. It go faster into the necessary softness with newer out tubes…

You might also fine this theirs worth attention:

http://www.goodsoundclub.com/TreeItem.aspx?PostID=2201

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-19-2006 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 3
Post ID: 2979
Reply to: 2941
Lamm ML2: 6N6P vs. 5687

Paul,

The idea of the not threaded forum is good that it is always there is opportunity to go back to all there and update own views, or to extend them. In many moths/years when the ML2 stop be a novelty for you, you might return to this thered and fine my following post worth consideration.

So, I went today to The AA Sewers ™ and have seen you were bitching about the Lamm charging $300 for a pair of the marched 6C33C and about the price of the 6N6P. Certainly I do not question the Vladimir’s right to make money on the intimidation and misapprehending the operation need for his products. After all, the Volkswagen use to sell their cars very cheap, practically at the cost, and made quite lot of money selling the services…

Anyhow with all my quite2xtended experience with Lamm ML2 there was one experiment that I never conducted and I am sorry now that I did not as it might be very interesting.

The ML2 second stage use a Russian made dual triode 6N6P. It is very critical tube in the ML2 circuit and it is hugely responsible for the sound of this SET. (BTW, change this tube one a year). The 6N6P is very good tube, one of the very few Russian tubes that actually sound very refined… but it is Russian tube… if you know what I mean… It would be VERY interesting to use in ML2’s second stage the best of the Western equivalents. Russians ripped up their 6N6P from Western 5687 (don’t ask me why but Russians very seldom designed own tubes but mostly juts mimicked western tubes). The 5687 is very well know and it is also VERY-VERY superb tube, widely used in many designs. The specifications are nothing dramatic but it has a very serious driver sound, is anything else as important? The 5687 has slightly less gain but all together it might be used in place of 6N6P without any change of operation point. It has different pins layout but it very simple to make a non-complicated tube socket adapter to cross-map the 6N6P and 5687. Sure a good version of 5687 might cost $6 or $25 but the 6N6P you can get for $1-$2, but I still, despite the economic advantages of 6N6P would try the Western tube. At least a dozen companies made 5687: Tung-Sol, Sylvania, Philips, General Electric, Amperex, Ratheon, RCA …etc… and it is suitable to be drop replaced by 6900, 7044, 7119, E182CC) instead of the 5687 (also I do not know how they sound).

Anyhow, I would generally do not proposed such experiments but if I have a change to putt the marvelous 5687 into the game then I would defiantly try it. As I said I am sorry that I did not do it when I used ML2. I still do not feel that 5687 will be able to address the sonic kisses I had with ML2 but… who knows… A driver is very critical part of any SET….

Rgs,
Romy The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-19-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 4
Post ID: 2980
Reply to: 2979
drivers, gain and relay pulses
Thanks for alternate driver idea, Romy.  Sounds interesting.

I certainly do not need all the gain from the ML2 along with my AI M3A phono/pre-amp, so I will give the 5687 family a try once I figure out a decent, fool proof pin-out adaptor.  Meanwhile I dread re-thinking my phono/pre-amp, whch I will need to do in order to get a better impedence/gain match.  I will start by simply shunting the volume pots, but I am thinking something more neutral (and quieter), so I am just listening to the cartridge, which is pretty damn good, really.

Right now my big problem is a violent switch-on pulse from the relay (not the on switch itself) in one amp only, which threatens to blow my speaker.  I could just fuse the speaker, I suppose, but I'd rather fix the pulse.

I got an 8' copper ground rod that I will use just for my phono, and I will try some Mu metal around the TT motor to see if I can quiet my phono noise enough to really get going with the ML2s.

So far, I am astounded at how few of the ML2s are in the hands of anyone who posts, and I am also a little surprised at the number purchased by "audiophiles" who believe they have something great but seem to think of the amps as prized possessions rather than thinking in terms of their musical potential.  In other words, they don't seem to be thinking outside the strong wooden boxes the amps came in.

One thing I had to admit last listening session is that these amps are "ahead" of my speakers, whereas the Wrights were way behind them.  I can see how you'd start thinking about horns with these amps, although I am just not ready to begin dealing with all the horn-inherent problems again, so soon after completing my DEBZs.

As you know, the ML2s do something really special with the "body" of the musical voices, without all the "3-D" nonsense, but giving that breathy weight to horns, with their sound ripping the air.  I will definitely be mixing in more orchestral music than I did in the past.

Best regards,
Paul S
10-19-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 5
Post ID: 2981
Reply to: 2980
Lamm ML2 is juts a tool…

There are no relays in the ML2 that might produce the “violent switch-on pulse… which threatens to blow your speaker”. What you have is a dead V2 tube. When 6C33C dies then it begging to produce the erratic pings. Juts replace the tube and you should be all set.

Anyhow, ML2 is won by many people nowadays but very few know what the have and how to use it. In fact it was always. People buy it just because the Media praises it but they both, the owner and the Media are clueless what and why the do what they do. I know at least 20-25 ML2 owners and 95% of them are complete Morons and have the corresponding sound from ML2….

Rgs,
Romy the CatPS: BTW, the less gains of the 5687 tubes has nothing to do with the less gain of the amp. You do need the driver gain to drive the output stage. Also, it a feedback amp and you will change the open loop gain with less drive of the 6C33C…. Anyhow, if you do not rally know what you do then I would not suggest you to experiment with it.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-20-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 6
Post ID: 2986
Reply to: 2981
Not too far out on the limb yet
Thanks again, Romy.  I never would have guessed that the relay-like pulse comes from a dying output tube rather than a fault with the relay itself; but that does make it lots easier to deal with!

As you know, meaningful info about this amp is hard to come by, with Lamm keeping as much to himself as he can , and most owners seem happy to just follow Lamm's instructions to the letter.  I guess that's the safest way.

Meanwhile, although I like to experiment I would never change anything about my my equipment unless I was reasonably certain that I was following someone who has a good idea what he's talking about.

I can read a schematic, follow instructions OK, de-solder and solder, but I do not pretend to be an electronics whiz.  I am in this for the music, not for DIY itself.  In fact, if I thought I could just buy what I wanted I would do it and never work on the gear!  Like you said, the gear is just a means to an end, ie, tools, and I try to know the tools well enough to control my results, at least to a degree.

Best regards,
Paul S
11-18-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 7
Post ID: 3175
Reply to: 2981
New tubes, same pulse
I got new 6C33Cs for V2s from Lamm because no one else wants to match them, let alone match them for gain; but the loud thump through the speaker still happens just when one amp self-switches from warming its filaments to full-throttle operation.  I don't know how this internal switching would happen without a relay or a thermistor, etc., but I'd like to find the source of the pulse and fix it before it blows a speaker.   Needless to say, I want to avoid shipping the amp from San Diego to Brooklyn and back, if possible.

I know this isn't a DIY forum, but you are the only source of meaningful information about the ML2 that I know of.  Others pretty much just piss themselves when the subject comes up, and although Lamm seems friendly enough he obviously regards everything having to do with this amp as proprietary.

Best regards,
Paul S
11-18-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 8
Post ID: 3176
Reply to: 3175
Debugging the Lamm ML2...

 Paul S wrote:
I got new 6C33Cs for V2s from Lamm because no one else wants to match them, let alone match them for gain…

There is no meaningful mutual conductance or bias matching for 6C33Cs (in context of ML2) besides gain matching, and to match gain of this tube is very simple with any special equipment or skills.

 Paul S wrote:
but the loud thump through the speaker still happens just when one amp self-switches from warming its filaments to full-throttle operation.

Paul, I do not know if I misunderstood you or you juts mis-presented the case. As I understood you, you complained about the pulses when the amp was operations. THAT would be because the aged L2 tube. If you have pulse when the amp accepts B+ then it is totally different story.

 Paul S wrote:
I don't know how this internal switching would happen without a relay or a thermistor, etc., but I'd like to find the source of the pulse and fix it before it blows a speaker.   Needless to say, I want to avoid shipping the amp from San Diego to Brooklyn and back, if possible.

I am sure it would makes sense to ask Vladimir about the possible reason but Vladimir has a tendency to do discuss problems with his circuits. In order to answer what is going on it is necessary to have the amp in hands. I do not know what kind delay it executes. As I remember it has only one relay switching and permeably it applies regulated voltage to 6C33C plate. I do not know how ML2 applies the plate voltage to the first and second stages perhaps Lamm does it the “cold” tubes at the initial start. Still if you hear an auditable pulse then you heard some voltage running across the primary of the ML2‘s output transformer. What might it be? A regulator, a 3200uF cap the transformer and then the tube…. I presume the bias is applied immediately as soon the amp is turned on. I really do not know. Perhaps that last large cap does it regulator create this  “ping”. Confirm that gas regulator holds the voltage during switching? Put a new amplifier tube in the regulator. Make sure that regulator does regulates and do not create any spike during loading itself to the plate of V2. Perhaps Vladimir was afraid to charge that 3200uF caps and has some kind of charging spreading mechanism in there that went out of the sync? Still, if you apply voltage to wormed and properly biased 6C33C then 6C33C should not generate any noise.  Hm… the ML2 uses global feedback… and perhaps something is coming from there… I remember the ML2 was very unusable when it was loosing 3-4dB of feedback…. Yet, without having it in hands it is difficult to say anything. Rehabs, some folks on this site who have some technical expertise would advise you.  Nevertheless, I do feel that Vladimir would perform an initial debugging with you over the phone… It is kind of his part of the game

Rgs,
Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-25-2006 Post mapped to one branch of Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 9
Post ID: 3206
Reply to: 2942
Cross-channel and/or phase effects and 2nd wave amplifiers

As I play the old-but-new-to-me ML2s more, and as I slowly replace tubes, performance has changed a lot, and all for the better.  Understand that I am not really talking about the ML2s, but about the sound I am getting, which is so different and so much “better” that I think it warrants discussion here (or nowhere), and I envision (or sense) a possible 2nd wave of hi-fi stemming from the possibilities exposed and highlighted by this amp (and its ilk).  Although it looks like it will be a while before I digest and process the effects of the ML2s in my system, I already have plenty to think about.  Lots of lights are going on, like flying over the countryside as night falls.

Romy already disabused me of the notion that the ML2’s effects are similar to the L1/L2 “X-Factor”; yet reading and re-reading his pieces on the L1/L2 preamps I am still left with the sense that I understand some of what he’s talking about from my time with the ML2s.  Specifically, I cited earlier and I still hear some sort of active re-tooling of the signal that “puts things (back?) in their places”.  Which sounds like a “fault”, but it isn’t at all in this case, at least not taken alone.  Also, there is so far an odd quality that could easily be mistaken for compression but is not that so much as an * almost *  SS quality of keeping a handle on the signal, compared to the SET “let it rip” approach.  The SS winds up being able to “push” the signal a lot farther than the SET, although the signal is always more or less compressed, while the SET gives the signal the freedom to “be itself”, and it dissipates and gives up way too soon.  So far, with no analog and the few CDs I have, the ML2s have not obviously “limited” the signal, per se, the situation being rather more like well-educated older parents showcasing their perfectly-behaved, well-traveled, beautiful children for other older, well-educated people who are not easily impressed with this sort of nonsense.  And the generally held opinion that good genes will out is certainly vindicated here.

Meanwhile, there are two things that just get stronger, that I want to talk about.  One is space, as opposed to soundstage or “stereo”, and the other is a certain hardness that makes on-axis listening too rough (at least with CDs), but makes off-axis listening phenomenal.

Previously, with my little SETs, the best results were generally on-axis, with a voluminous soundstage that really filled my large listening room pretty well, although there was limited musical energy forward of the speakers.  Now I am experimenting with the speakers pulled well into the room, much closer, sitting almost between them, and the musical energy just charges the air/space around me in a much more lifelike manner.  I assure you that this more than just 3-D sound effects, and in any case it has not been anything I have cared much about or looked for in the past.  But it is something I plan to pursue in the context of a certain necessary hardness that may or may not wind up being viable both on and off axis with the same program.

My phono is down and out with hum since I moved, and now I am wondering more about the “X-Factor” and whether it is desirable or too-something in the context of the already-factoring ML2s.  For sure, I have for some time gone back and forth on the old “straight wire with gain” ideal.  But I have had reservations about the AI M3A since I bought it, and despite some serious modifications I am not sure it will ever be pitched right to continue here.  I know Romy eschews parts swapping, but I will try some more coupling caps and grid resistors and get the phono going before I give up on the AIM3A, since changing that requires new phono and line stage auditions, and I just don’t have the time right now.  But if the bass, at least, doesn’t get into line, then, adios.

I will close this by saying that I don’t get around like I used to, mainly because I have become so cynical about the relationship between audio and music.  So I have no idea what is “out there” that may do what the ML2s do with an audio signal.  But whatever it is, I believe it is significant in a generic sense, and for me it is a harbinger of a 2nd wave that I now await with renewed interest in hi-fi.

Best regards,
Paul S
11-25-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 10
Post ID: 3207
Reply to: 3206
The “blending integrity” vs. “dynamic viscosity” .

Paul,

I re-mapped your post to your older thread; I hope you do not mind…

Anyhow, I find absolutely nothing in the older ML2’ sound related to L1/L2 “X-Factor”. As I suggested in the second post of the flowing thread:

http://www.goodsoundclub.com/TreeItem.aspx?postID=257

the L1/L2 are most likely use pro-audio tricks of “spatial expanders”. Sonically it manifests itself in unique pattern of “phasing of sound” – very beneficial and very desirable. In my years that I spent with ML2 I did not detect any “X-Factor” coming form this amp. It is also important to understand that the “X-Factor” is not something “nameless” but the very specific and vet well-defined sonic characteristic. One again, this characteristic is not belong ML2 but belong the Lamm’s L1/L2.

The most distinctive characteristic of older ML2 for me was its absolutely unique ability to demonstrate very “odd” but valuable integrity of “blending of tones dynamically”. There are not other amps out there that did it so fascinatingly. It is ironic any of tube rolling that you are trying now is not able to affect the ML2’s “dynamic tone blending”. The tubes will change the tonal balance and many other things but not the tonal blending. Even the Super Melquiades does not demonstrate that “blending integrity” in its HF channel (in bass and MF it is tine). Howevever, the Super Melquiades has different thing: the gass-biased 6E5P “dynamic viscosity” that in many instances overrides ML2 “blending integrity”. The “blending integrity” and the “dynamic viscosity” have different effects and I spent a LOT of time thinking if the “blending integrity” of ML2 is worth to be replaced by the “dynamic viscosity” of Milq's HF. I agreed to close my eyes to many other Melquiades’ advantages over ML2 if I conclude that ML2 “blending integrity” was worth to stuck with…

I thought that the ML2’s “blending integrity” comes for the fact that Vladimir regulated the output plats voltages. In many instances it should not be a big deal, or even to be a deterrence (dynamic is got eaten with regulation) but in case of 6C33C I heard from two other none-confirmed sources that it “might” work differently. I did regulate the 6C33C in Melquiades. I did not use 6C33C as a regulator but a set of three 807 tubes. I clearly preferred the non-regulated 6C33C built the Melquiades and ML2 have PS implemented at very different levels so I figured that non-regulated 6C33C is a way to go. There were then some thought that it might be the modulations of a full-range he amps make different but in the Super Melquiades I have some “tricks” that handle it. After all I decided that the key is in the transformer.

You see, no mater how minor delta between “blending” in my older ML2 and my new amps the delta did not exist when I used a full-range Melquiades. So, I consulted that the “blending” issues might take places because I used too “fast” transformers for Super Melquiades HF channels. Sometimes I plan to try other output transformers in there, the project that always was intended

Anyhow, as you see, even after a few years, still there is something things that ML2 can teach….

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-25-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 11
Post ID: 3208
Reply to: 3207
Blending integrity?
As I process what you have said about "blending integrity" I hear a trumpet blowing right at my face, just like I did last night.  But obviously this is my imagination at work.  Do you mean in general the way tones exist and integrate at different levels, timbre and SPL?  This is one way to identify a particular instrument and/or instrumentalist, but some people can do this with music played over the telephone.  It certainly becomes more complicated with chorale or ensemble playing, and of course most systems, including amplifiers, just can't do this (even though people insist they can...).  I am presently plodding toward the ability to enjoy this more complex music via hi-fi, and the ML2s certainly add options.  I think the dynamic improvements I noted figure into the "necessary hardness" and drive that charges the air at all frequencies, without amp-related compression or collapse at the volumes I have tried so far.  This off-axis air charging is not a small thing, and I am pretty excited about pursuing this.  No question that it comes straight from the ML2s, or at least of all the amps I've tried, this is the first time I have encountered it.  But it does seem to require re-tweaking system balance.

I have always heard the dynamic limitations of hi-fi, whether constant compression or crapping out with volume and/or complexity.  I listed above my present thoughts on the ML2s relative to generic SS and SET.

By the way, I have not been tube rolling with the ML2s -- yet -- just replacing the old tubes that came with them.  New V2s improved focus, bass, etc., and replacing the V1s cured the B+ relay pulse.  I will next try replacing the 6N6Ps, then the 12AX7s, etc.  I am not trying different tubes at this point, just making sure the tubes I am using are up to spec., so I can evaluate the amps and continue voicing the system based on optimum ML2 performance.

Best regards,
Paul S
11-26-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 12
Post ID: 3209
Reply to: 3208
Lamm ML2 tubes and plate current to loading balance

Keep the driver stage, the 6N6P, as new as possible. This tube is very critical for the given amp. You might get a tube tester and measure the mutual conductance but with the low price of 6N6P I think it is hardly necessary. I would change it as often as twice a year if you use the amp a lot. The 12AX7 can live in this amps for many-many years, find a good one get an pair and it will be enough to the rest of your live. The 3C33C should be changed in this amp once a year, with very minor variation of frequency of use and your preferred plate current.  The gas reference and the regulator amplifier might less for a few years as long as the plate voltage is stable and no nose is auditable. The big regulator tube I never changes and usually used the used up V2 tubes… BTW. You might get slightly more “juice” our of older ML2 by loading your probably 8R speaker (I do not know what you have) to 16R ML2 tap. You will loose some power but gain something that you might like. The tube will be slightly less loaded and you might with to drive it with less current. By doing the current-loading balance  *even the ML2  not as sensitive to loading as some no-feedback amps) you might dial in very precise harmonic balance of sound and very precise dumping of you LF section (sure the multi-amping will defiantly help)…

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-07-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 13
Post ID: 3267
Reply to: 3209
Back on axis with sweet 16
I tried the ML2s via their 16 Ohm taps, even though my speakers drop to 4R at about 80 Hz before going back up their average 8 Ohms at 30 Hz.  The overall sound off the 16 Ohm taps was more balanced and integrated top top bottom, even in the bass, and I went back to listening on axis, like I used to with my little 2A3s, sitting pretty close to my large speakers.  Although I still have issues with bass, it is obviously not a problem with the amp itself, and it is still much better than the 2A3 "bass", of course.  Unlike the small SETs, sound remains clean no matter how complicated or dynamic it gets.  There is no "cringe factor" as the music cranks up, if you know what I mean.  The amp has some almost SS-like control over sound, but it somehow always manages to get out of the way in plenty of time as it puts each note in just the right place at just the right volume.  Basically, it seems to have about ideal feedback, where the results are just "correct", not slapped around, held fast, shadowed or muffled.  With my speakers 16 Ohm sound is more "open" and yet it is also "richer" (which sounds weird, I know), not that it was "closed" using 8 Ohm taps. 

I can imagine that some who read this might get the idea from my descriptions that the ML2 is "obvious" in and of itself, and/or it "intrudes" on the music; but, oddly enough, I have not found this to be the case.  And although the ML2 does not "let go" like a small, classic DH SET, the ML2 still somehow puts out music that is simply more believably lifelike music than any other SET (or any other amp, for that matter) that I have ever heard.

Pitch wise, I am closer than ever and I am sure I can get exactly what I want from this amp by experimenting with speaker placement and some minor futzing with my pre-amp, cables, power cords, etc., ad nauseum.  I have a piano in the house, and this puppy with my speakers just nails piano sound and loads the room in the same way, too.

I promise to get better words to describe what I am hearing as I get more familiar with the new sound qualities this amp either creates or allows.  I am well familiar with the part that is so like live music but I am having a hard time describing the amps' part in it.  I wish there were more communicative people using these amps to talk with about them.  It's like learning a foreign language without actual dialog.

Best regards,
Paul S
12-08-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 14
Post ID: 3268
Reply to: 3267
I think ML2 is more capable then your speaker.

What speakers are your using? The “4R at about 80 Hz before going back up their average 8 Ohms at 30 Hz” is not good for SETs.  I prefer to have 16R and do not let it to drop below 12R.  Lamm is quite fixable with loading, probably because of the feedback. I do not know how Lamm loaded the output stage. It was possible to figure out but I did not care. Generally a full 6C33C might be loaded form 500R up to 1.8K, or in some cases even higher. It all depends of many factors within amplifier and with within speakers. Usually the 800R-1200R works out well. Sure the “speed” and transient capacity of speakers is a huge factor, as different speakers would handle harmonics differently… Do not forget that the tube drops plate impedance with raise current. Lamm is less sensitive for current change but still it is with auditable for bass the change between the 280mA and 310mA. Less current higher impedance but very interesting, although very minor improvement in bass.  Sure, you loose power, so add some voltage. Balancing the amp with sufficient voltage and sufficient current for the given signal, given loading and the given load it is possible to dial in very precise bass. I usually drove my LF pair of ML2 at ~185-190V and 280-280mA.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-08-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 15
Post ID: 3269
Reply to: 3268
No question, ML2 is more capable than my speakers (and everything else, too)

ML2 is also making me hear my modified AI M3A pre-amp, not to mention I guess I could now benefit from all shielded cables.  All this stuff was fine with the Wright 2A3s. 

Speakers:  I built a version of Dick Olsher's 3-way Diamond Edition BassZilla (hard to find at www.blackdahlia.com), and I tricked it out considerably from his mule.  Bass is BR, 15" Audax P380MR, which is a nice semi-stiff driver, low-passed at 150 Hz.  Lowther DX4 is high-passed at 150 Hz. All drivers share a 2' X 6' front baffle, and there are tapered wings for the Lowther, which is OB.  Lowther is notch filtered at 2.4k and 8k, to tame its "spikes", but I let it run itself out up top.  An Arum Cantus G2Si phases in at 10k, since the Lowther trails off from that point.  Driver integration is seamless.

Nework is passive, which I may address to deal with the impedance wavering from 40 Ohms at ~80 Hz (this is correct; I mis-stated it above) to 4 Ohms at ~50 Hz +/-.  Otherwise, load stays near enough to 8 Ohms, where it matters.

The best I have gotten from these speakers is the best I have heard, overall, certainly better than Avante Guarde Trios, overall.  Since I am so attuned to pitch and timbre, I have not found suitable horns, and also I like the dynamics I'm getting better than the tromboning I hear from horns, despite their stronger initial "push", which is nice.

Lowthers have well-known problems, but DX4 has better potential for correct tonal/timbral balance than Alnico drivers, IMO, and addressing the "spikes" changes more for the better than some might suppose.

As you say, the speakers aren't realized without a suitable amp.  ML2 may not like this speaker, but I can tell you it handles it pretty well, and likely as well as any off-the-shelf amp could.  These speakers are way too revealing for SS, and PP was a disaster, as well.  They sound great with the 2A3s, as long as you don't feed them a lot of signal.  ML2 is another kettle of fish, handles tons of signal, no problem, as you know, and way more clarity, and so astoundingly realistic in its presentation, it's uncanny.

Since ML2 is obviously better than these speakers, it looks like I can use ML2 to develop these speakers for a while yet.

I still have some other work to do before I start in with bi-amping, although that is something I have considered since the beginning.  I have also considered subs from the start, and if/when I get to that point I could re-address the crossover points, apropos.

Again, I just stay amazed that more people have not gotten onto these amps, especially since they are now available on the re-sale market.

Best regards,
Paul

12-08-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 16
Post ID: 3271
Reply to: 3269
Some truth about Lamm ML2 SET

 Paul S wrote:
Speakers:  I built a version of Dick Olsher's 3-way Diamond Edition BassZilla (hard to find at www.blackdahlia.com), and I tricked it out considerably from his mule.  Bass is BR, 15" Audax P380MR, which is a nice semi-stiff driver, low-passed at 150 Hz.  Lowther DX4 is high-passed at 150 Hz. All drivers share a 2' X 6' front baffle, and there are tapered wings for the Lowther, which is OB.  Lowther is notch filtered at 2.4k and 8k, to tame its "spikes", but I let it run itself out up top.  An Arum Cantus G2Si phases in at 10k, since the Lowther trails off from that point.  Driver integration is seamless.

Nework is passive, which I may address to deal with the impedance wavering from 40 Ohms at ~80 Hz (this is correct; I mis-stated it above) to 4 Ohms at ~50 Hz +/-.  Otherwise, load stays near enough to 8 Ohms, where it matters.

The best I have gotten from these speakers is the best I have heard, overall, certainly better than Avante Guarde Trios, overall.  Since I am so attuned to pitch and timbre, I have not found suitable horns, and also I like the dynamics I'm getting better than the tromboning I hear from horns, despite their stronger initial "push", which is nice.


Well, I’m glad you like your BassZilla, you with your ML2 might eventually evolve to more capable solutions. BTW, the Avante Guarde Trios are very complex horns that require a LOT of experiences and a lot of sensibility to make then to sound reasonably, practically no one did it. However, with all things being equal, the Trios had an upperbass horn that (with a proper and very inexpensive driver) made upperbass very far from what BassZillas could even dream…

Lowthers have well-known problems, but DX4 has better potential for correct tonal/timbral balance than Alnico drivers, IMO, and addressing the "spikes" changes more for the better than some might suppose.

 Paul S wrote:
I still have some other work to do before I start in with bi-amping, although that is something I have considered since the beginning.  I have also considered subs from the start, and if/when I get to that point I could re-address the crossover points, apropos.

I use 2 pairs of ML2 with LF low-pass built at line level. Do not convert your pair of stereo “vintage” ML2 into a mono bi-amped – it will make you get another pair of ML2. Though your BassZilla might “save” you….
 Paul S wrote:
Again, I just stay amazed that more people have not gotten onto these amps, especially since they are now available on the re-sale market.

Actually you are wrong. ML2 is on marker for almost 10 years and it has very god reception by audio public. Many reviewers drool about them, the users like them and generally people have gotten onto these amps. Still me, being me, I could not do not admit that that generally warm reception ML2 has own stink. You see, ML2 does not perform well in the fields. I heard/seen/familiar many installations with ML2 and I really know what I am talking about. Yes, the ML2 (whenever I mention ML I imply the “vintage” one can come to the room staffed most of other amps and demonstrate a performance that most of other amps couldn’t even touch. However, it does not necessary says that ML2 is “good” but rather that most of the so-called hi-end amplifiers out there are unspeakable crap.

The biggest problem with ML2 were “people” and “speakers”. ML2 did not have a good contingent of serious users (because most of the people in audio are Morons) and therefore that amp was not “seriously” used in the fields, at least as serious as it could be. Then the speakers…. The industry does not produce any single speaker that from my point of view would qualify to work with ML2. Of course the industry freaks created a lot of noise about the ML2’s glory with the… speakers that the industry had to push. However! Come on! Let get some sense of reality and conscious – ML2 with all these industry speakers did not sound well. Lars Fredell – the person who marketing-wise put Lamm on the marketing map was writing his glittering doodles and singing his odes to ML2 but at the same time he was driving his ML2s with … Verity Parsifal. The Parsifals with this 85dB sensitively and MF impedance shooting over the roof are still OK loudspeakers but not for use with ML2. There are many other amps, including form Lamm that did much better job in the Lars’ room.  I was there and I cat testify that Lars’ articles about the ML2’s advances were fraud and con. The Lars Fredell’s room sounded exactly like this – it was “so-so” with ML2 but it was not as near interesting as it could be if he “endorsed” more suitable loudspeakers. Anyhow, I could bring many-many similar examples but what would be the propose?...

This all brings me to a said observation that I think I have already made somewhere within my site. I recognize Lamm ML2 as a very unfortunate symbol of weakness, ridiculousness and foolishness of high-end audio. When in the end of 90s Lamm came up with ML2 the audio Morons took it almost violently. I remember it was impossible to open month mentioning ML2 because immediately a swarm of typical, “always-there” bottom-eaters ran to you, screaming with foam at this mouth that ML2 is overpriced peace of sonic crap. I remember somewhere in 2000 I was arguing with many idiots at AA about the ML2… and NONE OF THEM ACTUALLY WERE FAMILIAR with the ML2 sound. Still, any single Moron out there had a strong opinion about the ML2’s perfomance. Then the ML2 went south (I would avoid to name reasons), initially gradually and then the new revision - the ML2.1 was introduced. The ML2.1 revision has as much common sonically with original ML2 as a firecracker has in common with a ballistic missile. However, the ML2.1 receives IDENTICALLY glorifying and admiring reviews from the industry idiots as its predecessor and nowadays each second idiot who few years ago was spitting forwards Lamm has his ML2.1 sitting in his listening room. Still, the fact that the new production of Lamms sounds more like Krell amplifiers does nod bother anyone.

I think what was happening with Lamm is very-very indicative for the damn audio community generally. Most of audio Morons have no integrity, no conviction, not ability to recognize or interpret the factual results, no reference points and no familiarity with nature Sound. Nowadays the Lamms become a buzz-word for the cretins with audiogon-brains ask them “why” and they will hardly have any rational in their preferences or opinions.  Still, the “vintage” L1 (some of its aspects), the “vintage” M1.1 and the “vintage” ML2 (if they properly used) remind as some very special audio elements that, because of multiple reasons (with exception of M1.1), did not really find a deserving utilization in the world of Dominating Audio Moronity ™…

Rgs,
Romy the caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-09-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 17
Post ID: 3272
Reply to: 3271
The path that refreshes
As you can imagine, the ML2s simply surprised me.  I thought only of optimizing my speakers, what might drive them to their best, to see what they could do with fewer amp-induced limitations.  And the ML2s have done much of what I wanted on that level.  But now I also have lots more to think about than I bargained for, meaning my audio education just took an unexpected turn, not only for the "better", but in a direction I hardly anticipated.  And now that I have had a taste of this, it only makes sense to work with these new insights and attributes, this new perspective, and it obviously means making some changes now to areas I thought I had down.  Yes, the music sounds "great" now, but I have been at this long enough to know when there is improvement to be had, and the "promise" from these amps is too strong to ignore.

I first heard the ML2s driving some "salon" speakers, Vandersteen Vs, I think (or maybe giant Thiels...).  Of couse the resultant sound was nothing I could stay in the room with, but there was "something" about the ML2s, even then, under those circumstances.

But now that I've had them in my own system they are even more interesting than I remembered.  For one thing, I am particularly amazed at how they expose all other system weaknesses without ruining the music.  How can that be?  For instance, bass now is the best overall that I've gotten from these speakers, but at the same time, bass problems - exactly what they are - have never been so obvious.  It makes no sense!  I'ts almost like how my Ortofon MC 3000 II "sets aside" record noise.

The main enjoyment so far has been listening right into the music and being able to relax even though I now have several times the energy at a given volume than I did before.  Again, it makes no sense; but I like it!

When I said there are fewer ML2 owners than I would imagine, I really meant I have read far less of interest on the subject of these amps than I would have imagined, having used them.  It just seems like more people would be sharing the experience and talking about how to use them.  I may not get out as much as I used to, but I haven't heard anything this significant in many years, and probably nothing else I have heard to date is more "right" in such a significant way. 

So, where's the ML2 chatter?  I mean, crap, I don't want to wind up as cynical as you are, Romy...

Best regards,
Paul S
12-09-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 18
Post ID: 3275
Reply to: 3272
Audio is about people but not about metal.

I do not have any disappointment that there was no serious public overview of ML2. I have quite low esteem to audio public generally and to the people who facilitate public overview in particularly. It has nothing to do with cynicism but rather with objective observation of the reality out there. It is kind if shame as it never happened as the ML2 is gone and the current production of ML2.1 has nothing to so with ML2 legacy. In addition Lamm, as I understand nowadays abandoned any ideas of good sound and goes to cash out the market of mid 90dB-sensitive speakers buy buttering up his prospective customer on the idea of ML3. It will be basically the "new ML2 type Sound" approach only with the unnecessary 40W, based upon high-voltage-compromised, more powerful output tube.

Regard the rest. You might discover eventually that despite of beneficial contribution of some exotically performing audio-elements and despised that some of them are able to inflict long term listening consequences to listening culture but the only thing that counts is not the capacity of the audio installation but the way in which that capacity is used but the system owner. From this perspective all those audio toys are quite irrelevant…

I’m glad that you are in your way to discover the vintage ML2 – it well worth it. Spend a couple years with those amps – you will observe and learn quite a few interesting things. In 2001 I have written somewhere at AA that ML2 is able to demonstrate it’s sonic advantage even when it is not powered on. I remember that all Morons out there informed me that I was an idiot.  They are fortunate that they did not know how it really felt about their competence on the subject or about their primitive understanding what the subject really was.

The cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-10-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 19
Post ID: 3280
Reply to: 3275
Pulse tamed by "Ribbies"
I heard back from Lamms about the relay pulses.  They suggested I bias the amps again and then Lamms went silent when that didn't work.  But the problem disappeared when I got around to replacing the 12AX7s that came with the amps.  I happened to use some NOS ribbed-plate Telefunkens.  These not only cured the pulsing but resulted in astounding improvements to the sound.  Closing in on an hour of operation, the sound field grows - you can literally hear it swelling -  and then "something" "falls back" and voices and instrumental sounds "orgainize" and acquire a certain realistic density within the soundfield that I have never heard before through a hi-fi rig, in 40 years of futzing with this stuff.  Bass is now much more "of-a-piece", and there is every reason to believe that this combination of speakers and amp are capable of better.  I have for short spells gotten better upper bass from these speakers with the Wrights, so I think it's safe to deduce that the ML2s can better that, as I get things better arranged.  Each tube has a job to do, and I am now fairly confident that just replacing the tubes sent to me with the amps will make big improvements.  6N6Ps are next, if I can find some good ones, since I have no way of testing the "bulk" stuff generally offered.  Of course, Lamm remains an option, and I am pleased with the V2 tubes he sent me; expensive, but at least they are as advertised.

Yes, you are so right about people themselves making the biggest difference in their hi-fi results.  How many times have we heard a pile of the "top" gear making un-Godly noise?  It seems there must be a sort of tension between a purposeful going-forward and a readiness/willingness to yield to the right things when we encounter them.  And even though live music and hi-fi are certainly two different things, I have no interest in hi-fi that does not render certain musical traits fairly faithfully.  Like you, I can listen to the radio.  But that does not feed the same part of me that live music feeds, and my hi-fi actually does make a fair substitute, in addition to allowing me to hear amazing performances that now only exist as recordings.  That is what I am after with hi-fi: to get as much of an art/music fix as possible, and I just do not tire of some phenomenal performances, at least not with so many records to choose from, in addition to live concerts.

It would be nice if we could count on people to live up to our own versions of the claims they make for their products, or they could even live up to their own claims, for that matter.  But I have finally resorted to some hybrid form of intuition and voodoo to try to navigate through all the over-hyped, over-spec'd crap.  Too bad there is no way to guarantee that even the "best" gear won't wind up mis-used, apart from having a pretty good idea where we are and where we're trying to go.

Meanwhile, I have to say that a lot of amp makers out their owe it to themselves (and their buyers) to at least give the ML2s a serious listen and then factor the experience into their own thinking.  At any rate, I know of no other way to hear what this puppy can do, since I've heard no other examples, ever, and what this puppy can do should be a major factor in amp design and performance from here on out, IMO.

Best regards,
Paul S
12-10-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 20
Post ID: 3282
Reply to: 3280
Tactical sound vs Strategic sound and 6N6P.

 Paul S wrote:
I heard back from Lamms about the relay pulses.  They suggested I bias the amps again and then Lamms went silent when that didn't work.  But the problem disappeared when I got around to replacing the 12AX7s that came with the amps.  I happened to use some NOS ribbed-plate Telefunkens.  These not only cured the pulsing but resulted in astounding improvements to the sound. 

Yep, it happens. Tubes could go bizarre sometimes, even such a reliable as 12AX7. After walking over more then 40 different 12AX7s with ML2 I have seen some very strange 12AX7 behavior. The ribbed-plate Telefunkens are fine, I use them on my LF amplifiers that drove my line arrays. I find them too rough for MF use. Still, all Telefunkens are very different and they sound differently batch from batch. I have some (genuine) Telefunkens that sounded like “nothing special” and I have some that did phenomenal job. Interesting that with “better” input tubes ML2 might sound “better” in Hi-Fi sense, I call it “tactical” change in sound. However, with change of the input tine the ML2’s “strategic” sound is not affected. BTW, the driver stage more affects the strategic then the input stage. The driver stage is VERY important in SET.

 Paul S wrote:
6N6Ps are next, if I can find some good ones, since I have no way of testing the "bulk" stuff generally offered.  Of course, Lamm remains an option, and I am pleased with the V2 tubes he sent me; expensive, but at least they are as advertised.

There is no “good 6N6P” at least I was not able to find them. Get juts new 6N6P, with full cathode emission and it all that will need. The wearing of 6N6P very nicely shows on a tube tester but with their negligible price juts change them twice a year and it will be enough. I remember Lamm told me that the 6N6P are good for over 5 years… God luck with it… BTW, I did some experiments trying to found of if the early production of the 6N6P from 60s sounded better then the later production from 80s. I was not able to detect any difference.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-10-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 21
Post ID: 3288
Reply to: 3282
Sticking with a winning strategy
Your points about "better" versus "correct" and "tactics" versus "strategy" are well taken.  You are pretty good at saying things I have thought about for some time but never articulated, perhaps because there was no one to tell.  I have no wish to "improve" on the ML2's native capabilities (strategy) at this point, if only because I am not sure yet exactly what sorts of parts and what sort of a whole I'm dealing with.  So far I am having a blast, and I am NOT in a hurry.  I am mainly pleased so far that the old tubes I have replaced have allowed the amps to do what they do best even "better", and I do mean "strategically" as well as hi-fi sense.  I use one tube over another not to alter my/amp's strategy but to voice the system, ie, it is a hi-fi tactic.  My drivers are not as "hard" as yours, of course, and the ribbies give just the right edges when it's called for, and they also kick things down a couple of Hertz, getting pitch/tone/timbre pretty close to perfect in this system.  Some of the beloved-by-audiophile Amperex are very "revealing" and "air-y" at the expense of a certain "weight", and this is not something I wanted here and now.  I "like" the nice Amperex, too, but not here, now.
 
Well, if you couldn't find "good ones", then I suppose I will try the Ukranian on e-Bay for 6N6P, unless you have a better idea.

Any ideas for sources for 6AK5 and 5651A?  Seems like most of the ML2 tubes are "hard to find" from local sources.

I am also going to finally break down and try some Herbies, at least on the ribbies, even though the ribbies are among the "calmest" 12AX7s.  Again, tactics, not strategy.  Strategy-wise I aim to continue to play to the ML2's strengths.

Best regards,
Paul S
12-10-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 22
Post ID: 3289
Reply to: 3288
Other tubes for Lamm ML2

 Paul S wrote:
Any ideas for sources for 6AK5 and 5651A?  Seems like most of the ML2 tubes are "hard to find" from local sources.

I do not know why you say it. Both 6AK5 and 5651 are very common and very inexpensive tubes. The 6AK5 are penthode and dozens and manufactures made them. I had few or them, perhaps a half dozen of different brands, and I did not detect any huge differences in their sound. As I understand Lamm uses it as aerial amplifier in his B+ regulator to drive with 6AK5’s plate the grid of the 6C33C regulator. It is HF penthode and it is fast, nothing more requires from this tube, so it is no surprise that it did not affect sound tangibly. I ended up to catch a party of Western Electric 6AK5. Honestly they did not sound better or worth then anything else and I used them juts because the sexy yellow Western Electric letter across the tube.  I think I paid for them a few bucks per tube…

5651 is also is very common tubes. It is actual not a tube but a low current gas regulator on 80-90V. You can use in there absolutely any type of gas voltage reference diode that could regulate near 85V and can handle under 3.5mA. There are many substitutions for 5651 and many different manufacturers made them. I also did not detect any big difference in Sound in those tubes.

Do not confuse the Gas tubes that Lamm used in his regulator and the gas tubes that Melquiades uses.  If you read the thread from my bookmarks:

http://www.goodsoundclub.com/TreeItem.aspx?PageIndex=2&postID=2792#2792

They you might be under impression that gas tubes do affect sound, however Milq and ML2 use them differently. In ML2 the gas tubes are juts the voltage reference for stabilizer but in Milq the gas tubes supply bias, driving the grid of driver stage. Evan it took place via a large resistor but still it is way more mending duty. If I had ML2 I would change one resistor and would try a 35mA gas regulator instead of 3.5mA. In Milq the 35mA-type were better but it not necessary would means that they might be better in ML2. Those gas tubes are also a couple to few dollars per tube and they are good for years. The good part about the 3.5mA-type gas tube that there are practically not fake tubes among them…

The cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-30-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 23
Post ID: 3407
Reply to: 3289
6AK5: bass, feedback, organization
I did find replacement tubes OK (online), just not locally, like I had hoped.  I have now recieved, installed and tested all new tubes but the 6N6Ps, which have been delayed in St. Petersberg by Christmas mail jamb-up.  I think I already talked about sonic differences wrought by the other tubes not mentioned here.

So:  I have replaced with NOS each tube type one at a time to hear what, if any, difference each type makes.  New 5651s "leveled" the sound somewhat (Less "jumpy"), helped the sense of "timing", and they also helped somewhat with bass.  New 6AK5s made quite a dramatic difference.  Bass is now getting serious; not "fast" or "tight" in the tipped-up sense referred to by single-driver nuts, but real fundamentals with drive and articulation.  I have never had bass like this in my own system before, ever.

Another thing I noticed with new 6AK5s was much greater clarity, on one level, and much better "organization" on another level.   Music became "fearless", meaning no matter how crowded, condensed or loud it gets, it keeps the same quality, with no sense of strain or confusion.  This gives the impression that there's always plenty more where that came from, and it helps me to listen better.  It is especially great for close vocals that always overloaded my systems in the past.  Now lyrical expression (when it's there) is available through the entire piece rather than tapering off as the sound overloads or confuses the system.  I am more excited than ever to get my turntable going again so I can hear cleanly clear through the wonderful tenor/baratone duet from La Boheme (Jussi Bjoerling and Robert Merrill) that always did such a number on my system.  In fact, I'll be looking for another copy of the original mono EMI, which is brittle/scratchy, but with killer dynamics.

It is strange having this much clarity and HF extension with no real sense of "HF".  Previous SETs have always had that slight "glitter" or "shimmer", which some people just love, although it's not something I notice in live music.  It never bothered me, but I don't miss it, either, and it's absence certainly allows more room for music.  In fact, one might simply say that new (properly functioning) 6AK5s make for less noise.

Also since new 6AK5s, the sound has pretty much lost all relationship to the speakers.  This is very cool.  When sounds suddenly errupt now they appear totally without warning, and they can seem to come from almost anywhere but from the speakers.  This makes music so much more spontaneous, when appropriate, and more natural overall.

Romy, do you know the value of the input resistor on ML2?  Is ML2 input impedance really only 41k Ohms?  All my other amps have been from 100k to 200k input impedance.

My AI M3A pre-amp is obviously too strong for the ML2, with 30 dB line gain, and it also has 1.4k Ohm output.  I think I would rather just get another pre-amp than try to throttle the natural gain with resistors, and it would be absurd to try to lower its output impedance.   I have looked at the Herron VTSP-2 and thought this might work better with ML2: 100 Ohms only out, 15 dB only gain, and still suitable input and switching for phono stage.

Best regards,
Paul S
12-31-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 24
Post ID: 3409
Reply to: 3407
Lamms ML2 input impedances

Paul I slightly surprised about your comments. The regulating aerial amplifier tube affected sound very mildly, if ever, at least it was my experience. I had a few different 6AK5 but changing them was not a highly notable effect. I still have left a dozen of so of Philips Miniowat 5654SQ “Special Quietly” tubes, if you wish I might send them to you, as I have no use for them. BTW, be advise the all this tubes need to be burned in and they will change sound after then…

About the input impedance  - I do not remember the values now. I have the calculation sheets for my crossover somewhere and I might look for it… if I did not trash it… It has a voltage divider with I think slightly under one 1K in series and the shunt resistor that makes it 41K… Anyhow, why are you planning to drive the ML2 input to higher impedance? Your preamp can’t handle R41K? I usually peruse opposite and try to drive input impedance as low as possible with objective to load cables with current. I love drive cables with current, even with active bias current. If it were up to me then I would run 1A of DC though all system interconnects…. In fact I will do it sometimes…

Anyhow, the 41k is perfectly kosher impedance. As I understand Lamm made it to use with his line level preamps. His preamps are weak in output and they have difficulties to drive anything under 35K. In fact I make quite few experiments loading L2 with different values, even put there a very high quality trimmer and eventually I came up in my completely blind listening assessment with the best values…. To my satisfaction it was exactly near 40K…. Of course when I used 4 ML2 I was forced to increase the impedance as I paralleled the inputs. I use 80K in one amp and 105K in another. Do not ask me why they were not identical as it is VERY complex subject. Theoretically the balance loading should not affect anything but it did…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-31-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,148
Joined on 10-12-2006

Post #: 25
Post ID: 3410
Reply to: 3409
True values, true colors
I think the key to understanding this case is that it is beginning to look like the tubes that came with the amp all were over the hill, electrically.  Since I have no way to test them other than by ear, that is what I have done.  So far the only "special" tubes I have used are the input tubes, as I mentioned before.  And of course that change was quite audible;  not "strategically", but "tactically", and I am enjoying the results.  Again, the original input tubes were shot, electrically, too, so the new ones were of course an improvement in that sense, too.  The 6N6Ps I bought are nothing "special" as far as I know, but they are all tested and to spec, according to the seller, so I will also replace my current 6N6Ps when the new (NOS) batch arrives, and I will note any changes in sound then, too.

I would be pleased to accept your offer of the 6AK5 variant.  I will send my info (if it isn't already there) and I hope you will at least allow me to reimburse you for shipping.  Although the new (NOS) 6AK5s I used made profound differences (all significant improvements, by the way), I would not call these changes strategic differences, either, in the sense you apply the term, but I would say the new tubes simply allow the amp to better realize its design potential, electrically.  I have been changing other things around, also, homing in on the heart of the ML2s, and I am just amazed by what I am hearing.  I think I can tell already why you might try for NFB SET with your particular "dedicated", "narrow-band" set-up, but it is really hard for me to imagine that anyone could do better than the ML2s with any sort of conventional  ~HE set-up.  However, as great as the ML2s are turning out to be, I am very sceptical now about using them with speakers any less efficient than mine (96 dB), despite all the ecstatic hyperbole I've read from many audio reviewers who use them that way.

Despite your explanation, I can't understand how 1.4k Ohms out from my pre-amp could be optimum with 41k ohms input to the ML2s; that doesn't make sense to me.  And now that you mention the shunt, etc., it sounds like it would be wise to leave the ML2 input resistors as-is.

Best regards,
Paul S
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