morricab wrote:

Thanks for the info about transformers.  It is as I expected, however, that these passive devices are not passive sonically at all. I agree with you that the higher quality of the transformers should lessen the effects I noted (if not eliminate them) but the same can be said for active preamps as well.

morricab wrote:

I would imagine the character of the output transformer is even greater (much more wire involved and bigger magnetic fluxes).

morricab wrote:

Perhaps you are reacting to the fact that these amps are not SETs but push pull?

morricab wrote:

String up 8 6c33C tubes in parallel gives you 10 ohms output impedance and probably enough power (about 14 watts).

morricab wrote:

Have you heard such an amp before?

morricab wrote:

I do have a speaker with a flat impedance.  It is an Apogee Caliper Signature with an impedance variation from 3 to about 4.5 ohms over the whole range.  Fortuneately it is not so dead as your example as it has about 86db sensitivity.  However, it is like an electrostat in that inspite of having a low voltage sensitivity it does not sound "dead" like a conventional box speaker of the same rated sensitivity.  This could be due to the moving mass of the drive elements or because thermal compression of the planar drivers is not a concern like it is for a normal low sensitivity cone.   I also have full range electrosats so here again is a design good for OTL.  High sensitivity horns (with moderately high impedances) should work very well indeed and I don't see again why they shouldn't be OTL friendly.  You have a similar problem with matching loads with a SET amp of moderate output impedance.  You will certainly get frequency response variations unless the same conditions are met.

Really, with electrosats- ribbons you do not need an OTL but you need a super OTL, or some kind of direct-couple 400W-500W monsters with 5-6kV on its plate. Really those amps could not be recognized as OTL class but rather as a self-contained direct coupled aberration uses a remedy for some very faulty loudspeakers.

Ok, now you do hate me…
:-)

morricab wrote:

Well Romy, IMO they are not just tonally different they are more tonally correct, ie. they simply have less coloration than other technologies.  Just listen to a recording sometime made with a ribbon microphone and you will understand what I mean. Since you don't "live" in this world I don't expect you to understand but my experiments with amps on my Apogees has shown that they work quite nicely with moderate power (in a moderate room of course).   This hybrid amp that Dmitri (I think that's who) made for example would work marvelously on them.   I have managed to get perfectly accpetable listening levels from them using a 20 watt SET amp.  Why?  three words. No thermal compression.  Also, being a line source, the sound level drops with distance more slowly than a point source.  So doubling of power really gives a true 3db increase in output.  Levels up to 95db are possible at 3.5 meteres with 20 watts.  The sound at 70db is still exquisite.  The truth is that the 18 watt Lamm ML2 in a moderate room size (say 20 square meters) would do the job and sound wonderful.  Perhaps you have never heard what it can do tonally??  Horns, regardless of how good, are always colored compared to a ribbon driver.   In addition, there is now a guy in Australia who will be making essentially an Apogee clone but with high efficiency ribbon drivers and should be getting horn like sensitivity (ie. > 95db/watt) without horns.  If you are not experienced with good ribbon designs I suggest you acquaint yourself (no Magnepan does not count).   In truth, I like the best horn designs I have heard...better than any conventional speaker. I don't hate you for misguided ramblings.  Its like talking with a little precocious child .  There is a reason microphones are either ribbon or electrostatic in nature.  Response linearity, senstivity to small signals, low coloration, uniformity of drive etc.   The speakers have the same advantages.  Again, there are good designs and not good designs but that doesn't mean the concept is flawed in fact it is the best concept but difficult to execute properly.

You argue about ribbons lower distortions, bring irrelevant analogies with ribbon microphones, forget the mention then unavoidable front wave modification with any ribbon loudspeaker, compare ribbons with horns, avoid the subject of ribbons compression, mention the arguable subject of less coloration with ribbons and advocate the topology generally. Yes, any concept should be properly executed,  and I presume that you did it right: I will be glad to be invited in your listening room to learn.

However, there is a catch in all of this.

We in audio do not really prove to themselves or each other topologies or render the benefit of some given concepts. For me in audio, is very important my very much egotistic adequacy of my own experiences. For instance I experienced a certain event and felt how a certain attribute of my visions, me feelings, my personality and my own inner me reacted to this musical even. The event might be whatever it might be: live, recorded or broadcasted, the whole symphony of huts a minute musical phrase, juts a simple combination of two notes pronounces in a certain way…. All that I need from audio would be to reinstate the very same impact to myself when I would like to… there are always distortions…

Under the distortion I do not mean luck of harmonic linearity or anything else that might be quantifiable by a limited science but rather a deviation from the normal listing experiences that I have from the performed music. So how the ribbons/electrostats relate to all of it? The problem is that they do not relate. My “live” music, or the FM broadcasts, or my recordings experience might be closer or further from what I would like to get but the ribbons/electrostats experiences were always completely different, at least for me. When I listen the ribbons/electrostats I always instead of dealing with the music (or more precisely with my own reaction to music) I deals with my own alertness, trying to justify and convince myself that whatever I’m perceiving should be “good”. I mean with dynamic drivers I listen reproduced music “as is”, good Sound or bad, but I become MUCH easily gullible and credulous regarding to what I ma hearing. In contrary, with ribbons/electrostats I always internally extrapolate and interrupt sound into something ELSE and then, I listen that “abstractive something else”. To me, my experiences with ribbons/electrostats are similar with the experience of a bird dissecting when looking at the bird’s cut up wigs I’m wing trying to visualize a freedom of flying.

We defiantly might argue about the pure audio shortcoming of ribbons/electrostats (dynamic range, problems with complex music, disability to handle dynamic stress, killed lower frequency harmonics, tonal depressurization and many many others) but since I personally did not experience with ribbons/electrostats any noble musical listening sensations, and the direction that the ribbons/electrostats people took me before did not turn out to be fruitful, I do not think that I might be a very an attentive student to learn something about ribbons topology.

BTW, the amp the Dima designed was explicitly designed for a project (that went to nowhere) to drive the full range electrostats loaded into acoustic lenses. Dima clams that his amp feels very comfortable to drive 2uF capacitor….

Rgs,
Romy the Cat

PS: Do you think we need to start another thread? :-)

morricab wrote:

Hmmm....I guess I can't really see that unless you are enjoying a particular coloration you are getting from the TVC.

morricab wrote:

Afterall, as you mentioned the behavior of a transformer is non-linear whereas the behavior of a resistor (a good one) is linear, lower in distortion, and has no hysterisis (I think the same cannot be said for a transformer).

morricab wrote:

Resistors as a passive attenuator for sure lose dynamics but they don't affect the signal in the ways I heard from the TVC or the transformers in my Silvaweld preamp (which are good ones).

morricab wrote:

I have not heard too many parallel SETs but what I heard was pretty impressive. For example the New Audio Frontiers parallel SET 845 monoblocks are one of the very best amps I have heard.  Also, the Audio Note (kondo not UK) Kegon KSL is phenomenally good and is a parallel SET also.  Of course I have heard great SETs also.  I have heard great PP (Allen Wright's DPA300b being one of the best I have heard).  Yet I find the OTL sound to be less colored overall and more dynamic (especially in the microdynamic department.)

T,

I would like to ask you a question. Understanding that amorphous core material comes in many types still, if to generalize it them might I propose an observation that beside all amorphous sonic and technical advantage (presumably they exist) the amorphous core transformers have some sonic idiosyncrasies.

It hard to explain was it is and practically for me who is not familiar with relationship between the core materials and sound of the materials. Still, I know how it should sound and my observations that the amorphous core in some way very-very-very-very-very-very slightly depersonalize the HF. I would put in this way: if I build a 10-channel amp then I would defiantly use the amorphous core for MF channel and for mid FH channel. However, for the higher HF channel I would go for a super low inductance none-amorphous. What I feel that amorphous core make sound “strong” and “muscular” that is not what I want at the highest frequencies. Do not confuse it with the crappy silver sound or anything else: amorphous is problem free tonally. I ‘m talking about rather the “overconfident virility” at the highest frequencies then about some kind of “audio” problems.

Perhaps the amorphous core magnetic that works at the very HF should be load differently? For instance the transformer that work at the very HF should loaded much harder than it typically would? Perhaps it would bring out some “overly-richer harmonic content” and might slightly “soften up” the amorphous transformers?

T, would you elaborate on it if you feel that it has any merit?

Rgs,
Romy the Cat

Romy the Cat wrote:

T, would you elaborate on it if you feel that it has any merit?

morricab wrote:

As to the best transformers souding more transparent than the best resistors, I'll believe it when I (don't?) hear it.  You claim to have heard this but I most certainly haven't.

morricab wrote:

Based on theoretical arguments the noninductive metal film resistor is certainly more linear and less frequency dependent of the two devices.

morricab wrote:

I am not so sure the NAF amp has a typical 845 sound (I have heard only a couple of others that were handily outperformed by the NAF with not nearly its openness and speed) but perhaps it has a sound that is a function of the type and size transformers that are required for such an output tube??

morricab wrote:

Perhaps the "family" sound that one hears from the Audio Note amps is due to the use of their proprietary silver transformers?

morricab wrote:

Again then we would be back to the sound of the transformer affecting the overall "character" of the amp.

morricab wrote:

As to the Silvaweld input and output transformers:  You may be right but their literature says they are using high quality nickel alloy transformers.

morricab wrote:

I still doubt it would be better than no transformers.

morricab wrote:

If you look at the design and parts used they did not cut corners on this design so I find it hard to believe they stuck just any old transformer in there.

morricab wrote:

Interesting that you are so enamoured with a moded EL34 based amp.

morricab wrote:

I imagine it is possible, with proper attention to make a spectacular sounding amp with these tubes and the push-pull concept.  Tell me are you using it as a triode or are you still going "ultralinear"?

morricab wrote:

You may be right.  It would perhaps be worthwhile to look into "better" transformers but I am not sure that an advantage can be found over just going RCA to XLR adaptor into the balanced inputs and thereby bypassing the transformer altogether.  What do you think?

Thorsten wrote:

MY PERSONAL current realisation (where I to build one) would look like this: 1) S&B TX-102 as volume control, with suitable switch 2) 2V Lithium Battery negative pole to the grid of the Valve, bypassed with good non-magnetic silver mica capacitor and in series with a small, low q retardation coil, here for killing oscillation 3) C3g (it is currently "best sound for money" in the application) postal pentode wired as triode, many alternatives exist, the russian 6S3, 6S4, 6S45, 6E5 triode wired, EC8010, EC8020, E55L triode wired, E180F triode wired, WE 417A, WE 437A, 3A/167M and so on.... 4) Anode load inductor for C3g, I would use the S&B 120H/12mA 40% Nickel item 5) Mundorf Silver (or other to taste) Parallelfeed Capacitor 3.9uF 6) S&B TX-101 MKII as parallelefeed output transformer, wired for 4:1 stepdown 7) Valve rectified (GZ34/37) and Valve Regulated (O2A X 2, EF86 X 2, 6AS7) powersupply, around 130V @ 12mA X 2 for both Channels, AC for C3g heaters. The +B is besically adjusted for around 10 - 12mA current through the linestage valve.

May I ask you, this realization of yours… dose it has any own “sound”. My point is that if you plug this hypothetical unit right at the input stage of you power amp (not at the out stage of your front end) then what contribution of that “realization preamp” you would find be acceptable and what you feel would not be? You see, I have my “feeling” that it is hardly possible to make any tube-based completely transparent line-level buffer. Whoever engineers I asked, including my own very amateurish attempts, everyone suggest me that it is imposable.  Perhaps it was juts my experience… Anyhow did you look at the SS world for the “ultimate buffers”?

Rgs,
Romy the Cat

Romy the Cat wrote:

May I ask you, this realization of yours… dose it has any “sound”.

Romy the Cat wrote:

You see, I have my “feeling” that it is hardly possible to make any tube-based completely transparent line-level buffer.

Romy the Cat wrote:

Anyhow did you look at the SS world for the “ultimate buffers”?

Best buffer in production I know is BUF634, out of production BUF03 immediatly followed by a complementary FET PP Buffer (same as Curl is fond of using). They are not completely transparent either and need a really good powersupply as well.

BTW, here the schematic for our preamp, signal section in principle, parts choices see previous msg, other suppliers for similar parts exist:



Ciao T