I have expressed this attitude before and I think it bites me by my tail again. Everyone tells that electrolytic in POS are bad. Well, I kind of follow this thinking as well but up to the point. The true is that I never was able to beat actively biased electrolytic in my speaker level crossover and I generally have no problems with electrolytic in PS.

The film is better but the question is which film?  The polystyrene, Teflon or polypropylene and foil do very nice but they usually are small values. If we need the PS-level values and not willing to have 1 cub feet of capacitors then we go for metalized film caps. Here is where the debate of film vs. electrolytic is reversed – I hate the metalized film caps.

I can’t even start to describe how much I hate the metalized film caps – they are not mellow but they are rather eat all texture and transients in sound, literally converting my Vitavox into Altec.  I have dozens of MPK caps that I collected over the years and they all sound very identical.

A few days back I put Obblegato film cap into my MF channel.  Obblegato is large and I thigh it might be different but at this point it does the typical “metalized” thing and to listen my channel more or less tolerably I bypass the Obblegato with 100uF 450V Nichicon electrolytic.

Now, the Obblegato is new and it might burn his “metalized misery” over.  Alternately I might get for a large bank film and foil – I do have space in there and I need just 10-20uF. In worse case I will stay with electrolytic that ironically it my best case. So, does anyone have an experience to observe the pattern how the sound changes in the 500V Obbligato MKP cap while the caps are break-in?

Paul S wrote:

Where MODERN electrolytics shine is specifically for PS use

I have to agree with it. Furthermore when I agree I back up my word with actions. This morning right after I posted my post above I opened the amps and   trued a dozen of caps in the Obbligato position. My original electrolytic was so above of everything that it was not even contestable. I decided do doe not waste my time anymore and let my electrolytic to leave in there permanently. I use my typical Nichicon Low Impedance 100uF 450V 105c, it is know that I am fan of Nichicon. In fact it was so good that I did s0omthing that I did not expect – I removed all film caps from my single stage amp that now drives my tweeters. It is it – there is no film filtration in Melquiades power supplies anymore….

I know that the idiots from DIYAudio would declared me as the Four Horsemen of the Apocalypse but if they did then I do something right….

I have finished all my frustration frustrations, connected all 12 Melquiades channel to Macondo and quickly, but not finally calibrated, the channels.  I finished in the middle of the Simon Boccanegra’s prelude as they started today an hour earlier and I did not know it. I tune the recorded and eventually dumped myself on my couch for the next 3 hours…

The Verdi’s “Simon Boccanegra” with bass-baritone José van Dam was beyond believes. What also beyond believes was the sound from Macondo. God, I so missed that experience! Live broadcast, the full Sound of Macondo, to spend a couple hours with it, marinating room with a good cigar, without thinking about the means and methods but just to listen the event, to experience live artisticism, to let music to fly you away, to think about Sound… I did not have it over a month as I took apart the left Milq and today the all “invoices were paid” – the Macondo is back, better then ever. Was it better then ever?

Well, this is a complicated question.  I removed the film caps from my right channel and now the single-channels amps of the Melquiades that was not converted to DHT go some transients that I was so complaining last 6 month, since I went for PurePower electricity. Macondo did incredibly well but do I recognize that better sound of my new sexy DHT channel. Well, I have to tell that I am not sure. The sound of individual DHT MF is definitive and in a way distinctive but being incorporated into Macondo 6 channel I was not sure that I can recognize this distinctiveness. Put in this way, listening the whole Boccanegra I did not detect that I had different topology of MF amp in right and left channels. I would tell you even more- after the 2 act of the performance I decided to change the Chinese 2A3 to Valvo LK4110 from 40s. They are very differently sounding tubes but I would NOT say that I was able to recognize this different in the 3 act.

Perhaps I need to fine-calibrate Macondo and Milq differently with respect to satellites that Melquiades has now. I am sure I will learn about it in coming weeks. For now my playback is back fill-time. I have at this point no plans to convert my right Melquiades to DHT. I will keep it as is for a couple months and see where I found myself then.

I am in minor scale mode toady and play mostly chamber music and only records. FM broadcasts with all their majesty are hardly objective tool to assess what doing on with audio. So, I play records and tapes. Besides everything I am trying to figure out if my DHT map is working in a way I want. I would like to say that it is but most of the time I do not see a lot of difference “before” and “after”. I think today or tomorrow if I have time I will fine calibrate all channels and perhaps my view change but for now it is how I see the things:

There is not a lot of difference I can recognize between performance of my right channel with single-stage amp (with new no film PS filtration) and the performance of my left channel with DHT. There is some difference and it might be so far described like this:

1)      The DHT plays a bit more flexibly. The tones enter own boundaries kind softer and it is while the channel maintains the same transient and contrast characteristics. It is like you lay down on a floor a toolbox with hammers and screwdriver vs. you lay down on a floor a very delicate vase made from very think glass.  I am sure you would care the vase more delicately, so the DH channel, at lease it appears like this as now.

2)      The imaging that Macondo use to throw is not there. I know, I know. Now some Morons of Joe Roberts begin to complain that I use the word “imaging” and that they heard it 32 year backs. The subject of their protest would be that they were clueless then as clueless now what it all means and thereof I shall not be mentioning it. Well, let leave the audio-handicapped alone, I hope they learn a few new audio-words and will impress the hoodlums at audio trade shows – there is their level. In really imaging is a very first indicator that something is wrong and even a system organizer does not know yet how to USE imaging then imaging might be an early warning debagging tool.  So, Macondo’s imaging is kind of odd. I play Brahms and Schumann by Guarneri Quartet and the Haydn –dedicated Mozart’s quartets by Quartetto Italiano.  The music is there but imaging is in a way very primitive. This effect of mental layering is not there, the way how tone delivered from right to left is kind of mechanic and unmagic, the dynamic of depth is there but it being used kind of vulgar. It is generally friendly sound imaging-wise but not sophisticated. I have no idea at this point what it is, I will look into it further.

Anyhow, I think Macondo calibration will be revised a bit. The channels and filters stay where they are but the arrangement of the outputs will be slightly changed. I have an idea what I would like to go, let see where it might bring me…

Imaging is usually one of the last things to come correct during warm-up and/or "break in" (providing, of course, one buys into the idea that parts/equipment may need breaking in in the first place...), and who knows how long this piece will take to break in.  Do I remember you saying that the Nichicons take a while, and that they generally follow a pattern that includes a stretch where they are not very good?

In the end, there "should" be a wider range of textures and timbres and greater ease that at first sounds "slower".  On the downside, the sense of "immediacy" might take a hit, even if the music actually sounds more "live" when you really think about it.

Best regards,
Paul S

Just like my idle mind to finally start wondering about phase (with the filter and the two stages).  I think I remember you said you don't generally worry about phase: but most of us notice at 180 degrees.

In case of such a serious problem, a serious, sophistocated solution is called for: swap the speaker leads.

Meanwhile, the "new" MF driver is still down on the "main deck" (with those long-ish leads...)?

Best regards,
Paul S

Spending some time listening carefully my new setup after fine-calibration I recognize some inaccuracies in my previous comments and some mistakes of my original objectives. Here are some observations I would like to make. If some of my observations contradict what I observed before then it is what call evolution and refinement.

Sound of a single MF channel when It is driven by one-stage 6E6P (with “new” PS schema) and the sound of my DC-coupled DHT is slightly different but without obvious advantage of any of them.

If any advantage does exist then it becomes practically negligible then MF channel incorporated into 6 other Macondo channel.

The change of the output tube in the DHT channel is well-auditable. However, the values of this change is very different then the values of the same change that might be viewed in an amp that drives only one channel. This is very important observation.

If change of output triode in one-channel operation might be evaluated from a position of full balance of the tube then the same change within 6-channel operation might be evaluated only from a perspective of complimentary balance.

Therefore any fine calibration of sound in case the left channel use DHT and right uses one-stage 6E6P possible only for a single DHT tube. The change the DHT change the flavor of sound and the “flavor”  balance between right and left channel shell be recalibrated and in some case might not be reached.

The idea of DHT MF channel is in way a fiasco as it is not significantly better then one-stage 6E6P (with “new” PS schema - that is important). At the same time the DHT MF channel, by virtue of replacing the flavor of output tube is a phenomenal opportunity and a great triumph as it allow to  tweak the contribution of MF channel to the level unimaginable when the one-stage amp was used. The full potential of this would be available only with DHT running on both right and left channel.

That is all for now folks.

Paul S wrote:

I do continue to wonder if a long path through an electrical storm, from the driver plate to the DHT grid, is perhaps bringing something to the sonic smorgasbord.  Is this run anything special in the way of wire or shieldiing?  Should it be?  Would making it shorter change anything?

I asked myself the same question. The wire I run is long. The distance between the driver and the output state is 14” and I made is a 3.5” longer and I decided the run non-shielded wire and not direct but around the places where I feel would not be “inductively dangers”.

I consulted with a number of people who feel that they “know” and they stressed that this DC-coupling wire is super significant. They might be right but I did not feel that it is all credible as the loaded me with other “super significant” comments that I personally degree. So, it is very difficult to say what is what. The DIYer might run their mouths about any subject and since I personally did not hear what result they are getting and since they never were in my place we can’t correlate what Sound we consider “acceptable”. So, I have idea what to think about the wire for DC-coupling.

From one perceive it shall be very important as it goes to grid. Anything the goes to grid is critical. If you remember I wrote that changing the path in which my fix’s bias was supplied voltage to 6C33C grid did impact sound. From another perspective the signal already quite robust after the driver stage, so go figure…

I took a regular 22ga pure copper wire with Teflon jacket and juts run it. I do not write DIY books and do not need to be “correct”. If Sound is acceptable then I less care about the “minor things”. The sonic result that I got so far did not make me worry about picking the “little things”. So, I kid of sold for whatever is there, sure it will be more fun to run a vintage Dominus in there… but I do not see myself spending time to do it.

Romy the Cat wrote:

Spending some time listening carefully my new setup after fine-calibration I recognize some inaccuracies in my previous comments and some mistakes of my original objectives. Here are some observations I would like to make. If some of my observations contradict what I observed before then it is what call evolution and refinement. Sound of a single MF channel when It is driven by one-stage 6E6P (with “new” PS schema) and the sound of my DC-coupled DHT is slightly different but without obvious advantage of any of them. If any advantage does exist then it becomes practically negligible then MF channel incorporated into 6 other Macondo channel. The change of the output tube in the DHT channel is well-auditable. However, the values of this change is very different then the values of the same change that might be viewed in an amp that drives only one channel. This is very important observation. If change of output triode in one-channel operation might be evaluated from a position of full balance of the tube then the same change within 6-channel operation might be evaluated only from a perspective of complimentary balance. Therefore any fine calibration of sound in case the left channel use DHT and right uses one-stage 6E6P possible only for a single DHT tube. The change the DHT change the flavor of sound and the “flavor”  balance between right and left channel shell be recalibrated and in some case might not be reached. The idea of DHT MF channel is in way a fiasco as it is not significantly better then one-stage 6E6P (with “new” PS schema - that is important). At the same time the DHT MF channel, by virtue of replacing the flavor of output tube is a phenomenal opportunity and a great triumph as it allow to  tweak the contribution of MF channel to the level unimaginable when the one-stage amp was used. The full potential of this would be available only with DHT running on both right and left channel.

Of course I do not argue ageist better quality tubes and in context of a full-range operation the more superior tubes do produces better and in some ways unique result. For instance my RE604 and particularly YO186 produce sound with truly unique character. The uniqueness of this character loses a lot of value when the system is bi-amped.  However, in the situation of the “unique character tube” operates in band-pass between two other fine-adjustable channels then the unique character of this band-pass tube does not expose itself too much. Well it does expose itself BUT using another less “unique character tubes” and recalibrating all 3 channels you might write any characteristic of this “middle” tube.

So, 3+4+2 = 1+5+3 and it looks that it is true not only in mathematics…

Romy the Cat wrote:

I always was kind of afraid of it. Any single zillion years tube I see is “NOS in box”, “measured as new” or “never work”. So, I wonder where those uses up old tubes are gone? Do people trash them or juts sell them “as new”. As many old tubes I ever bought with quoted transconductance figures never were the same after I received the tubes I am not even talking about “match tubes” what is always is a pure BS, they never matched at the necessary for me operational parameter, or gain. It looks like that with DHT tube it is even worth. I measured the 2A3 and 6A3 that I have and they are so much off the specks what that it is not even funny. When I buy Russian 6C33C then they measure whatever they want then it is fine as they cost nothing. Those DHT tune are expensive but the same crap quality wise – very said. Looking at this I might understand Lamm who sell 6C33C for $100 per tube, assuring it compliance with specs.

Interesting. I think that with testing just for:

- gain
 - bias
 - distortion
 - power output
 - hum level balance

It is not necessary give an objective picture about resources of a tube. We can monitor the change rate in the tube bias as some of them change it as the tube get older, we can monitor distortion pattern change but we can do it only for a given tube to recognize how it ages. I was under impression, perhaps mistaken, that transconductance is the most objective evaluations criteria as it has voltages, current, gain and impedance melted together, I think it called transfer conductance sometimes…   I have two good testers but I do not measure transconductance for output tubes. My 6C33C out has different criteria that allows me to be more accurate then transconductance. But with the DHT tube I am confused how to measure then objectively. I think that the gain and bias, particularly with my cathode bias do not say anything about the state of tube. IT would show what brand and vintage have comparatively more current or gain but it would not indicate how much cathode emission was used for a given tube, not much cathode is poisoned and how much the tube is gassed.

Romy the Cat wrote:

BTW, I have a local Bostonian guy have replied brought today a very interesting DHT amp. He has a number of DHTs and this one he reports is the special one, quite expensive as well. Although the electricity was not good today but we did some listening and the results were very quite interesting. I am still contemplating about them and will post what I think what I have more organized thoughts.

floobydust wrote:

One of the reasons I no longer use a tube tester. They make a measurement at a specific target operating point(s). You don't really know what it is, so what are the chances they will be close to your actual circuit operating point? So choosing a close match of tubes that perform the same across the noted parameters (in the actual amplifier(s)) just makes more sense to me. If the pair of tubes are the same manufacturer and internal construction (and unused), then they should age well together and remain fairly matched in long-term operation.  Just for fun, I took the final output stage for the DHT amp and normalized it (i.e., subtracted the DC shift for direct-coupling) and modeled it in the SEampCAD program. I plugged in the details for the output iron as noted. Normalized values result in 1.125K cathode resistor and a 280V plate supply. Values work out to pretty much what you show in measured values.  Transfer curve is quite good considering the lower current. Maxmum power output is about 1.85 watts with pretty low distortion. I can probably create some PDFs for the output specs and curves and email them to you.  Based on the values you are currently using, you can put a 45 triode in the circuit without any change and it will be just as clean but less power... about 1.2 watts. Should be an interesting experience. In many respects the 45 is the purer tube design and many prefer it soncically over the 2A3, "IF" you can deal with 2-3dB less output power.

First, thanks that taking your time for plotting my amp. I think it good and I have no problem with output stage. If would pick fleas on its design then it would be the first stage. It run at juts 10mA and 150V – a VERY conservative operation for this driver. I can not driver it hooter as I would then need a higher voltage on the output tube’s anode. It looks like the driver tube still sound good but I have another concern. At this operation I have only 2.5V on driver grid. At my normal 200V and 20mA I have 4V on grid. The 4V on grid is good as I can swing any input voltage and have an assurance that I will not send the driver into A2. With 2.5V I still far from danger but it is closer then with 4V. So, the 3dB voltage divider at input is kind of extra protective measure to keep the drive state from overload.

Why I said about the déjà vu is because a coupled weeks back I did think about the 45 tubes. I even bought a few for test but they arrived damaged and I sent them back. I need to but more of them and finally try those 45s. You said that might have 2-3dB less output power. I usually do not understand power in decibels I understand gain in decibels, and as I understand I will have both of them less…

Anyhow, my concern about the 45 tube is the same that I have with my YO186/RE604 tubes. All my 4V tubes sound softer then my 2.5V tubes. The 45 tubes with their plate impedance 500R higher then YO186/RE604 I will have even harder loading of those tube against my 6K output transformer. Now, if I find a way to make primary with taps of 6K and 9K then I will be able to drive 2.5V tubes against 6K and 4V against 9K. Since I do not use them at the same time I will be able to keep them permanently connected. Now, the whole beauty of my current arrangement is that I need to do absolutely nothing to switch the amp from YO186 to 2A3. If I stick into the 2.5V socket a tune with 1.7K plate impedance then I need to remaps it to high impedance primary… So, I need to come up with some kind of arrangement that have flexible primaries, also to switch them and do not degrade sound.

Anyhow, I will order some 45s and will see how it goes…

Very cool results I’m get in here. I took the new Slagle’s transformer that has reconfigurable sections and put it in the Milq.  With 13V on primary I have 625mV or 520mV on secondary, or 20:1 and 25:1 (with 200-300mV normally drive the speakers at cruse volume). The lost of gain is manageable and I have enough in my LPAD to compensate it. In fact I think I will have enough gain even for 45s to try….

It is unquestionable that my 4V tube need more then 20:1 and with 25:1 they begin to sing, particularly the Klangfilm KL-71403 and YO186. They got some transient thump and sound just wonderful. What particularly is very cool is how genital they enter high dynamic – they do it with dignity and with amassing grace.  I would not say that my 2A3 are losing in something, I am not at the state what I would make those observation. As I told with DHT MF in band path I can make any tube to sound as anything but as it is calibrated now the 4-volter do very serious job in MF.

Now, about the mistake. I did not think about it before I have done it but not I see that it would be very good idea to have an automated compensation for gain lost when I flip a switch from20:1 and 25:1. It would not be default to do but as not it is gone, so I would need to find a way to fine-calibrate my LPAD, probably getting one of those old knobs from old scoops….

There was a very funny moment. I was listening one MF channel just with YO186 and restarted the amp. The Helsinki Philharmonic was crashing through the reticules Samuel Feinberg's Piano Concerto (if it were LP then I would swear that it was played backward) and then suddenly someone knocked in my door.  I went to open but no one was there. To my surprise it was how the YO186 played the bass drum. There is some sense of “aluminum insanity” in the way how YO186 stress the bottom of S2. It sounds “distorted” but so … lucrative and attractive! I would LOVE to hear a full-ranger with YO186 with a “right” driver. It would be nice to know what the “right” driver might be. Perhaps I need to convert my Sun Audio crap into full-ranger YO186 and for an assault trip?  I wish I have ego to it… but it is pity as it might be a very interesting full-range DHT SET.