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Experimenting with different preamp tubes, and or input driver tubes. I have come to these conclusions.
12AT7: The most quiet of the common 12v. A little smoother tone than other common 12v. Less coloration than other 12v.
12AU7: Not as smooth, but smoother than the 12AX7. Sweeter than the 12AT7.
12AX7: The most gian, but not as smooth as the other 12v. Still sweeter than 6v tubes. In fact all the 12v are sweet compared to 6v. All 12v more colored than 6v.
6SN7 Can sound very much like a 12v. In fact I refer to it as a amped up 12AU7. Definitely colored compared to a 6922.
6922: Nearest to neutral sound. I refer to them as the " solid state of tubes " Can be analytical, and harsh sounding. Can be great if you purchase NOS, Telefunken, Amprex, Siemens. don't really care for any of the current manufactured 6922.
Of course all these observations dependent on gear involved.
Just my thoughts, observations-
I found this quote on a review. He hit the nail right on the head with the 12AU7!
" I asked to demo the Elyssa, a 35 watt integrated amplifier using KT88 power tubes and ECC82 and ECC83 in the preamplification section, in my experience this combo makes for a very balanced presentation between the warm natural musicality of tube sound of the ECC82 "
I guess I opened myself up to various thoughts and questions unawares.
For years I had a friend with an excellent ear, that was the manager of a high end store. When I had the time I drove to his store and listened. He had an excellent ear and taught we how, and what to listen for when comparing equipment. It was he that taught me how to mix certain tubes to produce a certain trait in the sound. His store was a ways away, so I chatted on the phone with him whenever I could. He had an incredible knowledge of audio equipment. I could call him and ask him the difference between 2 preamps and he could give them without hesitation, and let me know which was better sounding ( in general ) and which was built better.
The above is where I learned to listen and compare tubes.
Can I remember exactly what a tube sounded like in every piece of gear I tried it in? No- But let's face the facts. CJ manufactures their gear to sound like CJ. It has a distinct CJ sound. Same with Cary, ARC, etc. The same with tubes. No matter the year or manufacturer a 12AT7 will give a certain 12AT7 type of sound to the music. Did the manufacturer plan this, or simply employ that tube for it's electronic attributes? Remember, they are trying to make money. We are the ones that make it into a science.
What is sweet? I guess all tubes have a sweet sound to them. SS burns my ears! It's that different order distortion business you know :) But a EL34 to me will always be sweeter ( more euphoric ) than a 6550. But instead of " sweet " try easy listening. The EL34 has always been at the top of the list for tube lovers to produce that magical mid range at a good price. Most SS is cold, and analytical. Note I said most. At least to my ears. If you still don't get the meaning of sweet. Find a VAC CLA1 and hook it up to a pair of Quicksilver Mid Mono blocks running Tesla EL34's, and a pair of Vandersteen speakers. You will find out what sweet is in a hurry!
Consonance gave themselves a bad rap. Their equipment is attractive, and well built. Unfortunately they didn't make it very easy to use for the average user, tube roller at the start. Plus they didn't advertise here in the U.S. But I like the sound of what I have heard. I never had the chance to roll input and driver tubes in my Cyber Signature 100 as my collection of tubes was in storage in another city at the time. I will say I have heard a at least as much difference in the sound, by changing the input, driver tubes in a amp, as I would by changing the output tubes.
Hope this makes sense (~_~)
How long ago was this tube shoot out done, since your test gear is gone. I mean if you are going by your remembrances that may not be accurate considering all the brands and types or tubes you went through. Unless you have a photographic memory?
You won't know what a preamp or line stage or driver can really do until you build one with DHTs. Tubes like 26, 01A, 10Y, 4P1L
Look at the Bartola Valves site - it's all there.
Music sources. Photos are nice!
I almost forgot. I had a Consonance Cyber Sig something ( forgot exact model ) it ran 12AT7, and 6sn7, as well as a variety of output tubes. Anyone remember the model? I dumped it after re tubing it as one had to remove the bottom cover and bias it from underneath. What a pain for tube rollers!
I also had a friends demo VTL 2.5 that I rolled a few tubes through. Most of the gear I owned was prior to smart phones so pics were not that plentiful. I never was into snapping pics that much anyway. Most of the time I ran Vandersteen 3a sigs, or Meadowlark Kestrel Hotrods. I still have the Kestrals, but there boxed up as I just had them shipped back from my brother. Want a pic of the boxes?
I own the less fancy work model called the M100 plus. There are several variants of this amp. This was the amp that got me hooked on tube rolling. Not sure if I love it or hate it for that reason. It is very sensitive to the input and driver tube rolls. I am surprised you didn't get caught up in rolling the 6SN7s. My amp was not compatible with the 6DJ8/6922 family, only the 12--7s.
As far as your comparisons go, I am not sure what sweet means to you etc. This is the problem we suffer in trying to discuss sound intelligently. That is aside from the physic/electronics.
No pics other than this one which I will let you guess. Most all of the gear is gone now.
Sources were Rega Planar 25 turntable. CAL CL-15. CAL CL-10 ( still have this thing laying around ) Conrad Johnson DA/2b.
Preamps included Melos Sha Gold. ARC LS-15. CJ PV12AL. BAT VK3i. BAT VK5i. Rogue Magnum 99. Rogue 66. Belles 20A. VAC CLA1 MKII. Custom made 6sn7 can't remember the guys name that made it for me. Found it on ebay years ago, wish I would have kept it!
Amps. Quicksilver M60. Quicksilver M80. Quicksilver V4. Quicksilver Mid Mono. ( all mono blocks of course! ) Rogue 88. VAC PA90. Cary SLA-30. Cary CAD-50 MKII. CJ Premier 11a ( magical with nos GE6550! )
You sure are inquisitive :) I hope you don't want a review of all that equipment :) I will say however if you like sweet colored euphoric music. The setup I had that worked the best was VAC CLA1 MKII ( which had a triode switch inside ) Quicksilver M60, just about any source you want, and Vandersteen Sig 3a. Incredibly smooth, but the M60's had a soft bottom end.
I listen to Jazz-Blues. Hank Crawford, John Coltrane, Miles Davis, Grady Gaines, John Lee Hooker mostly. Some vocals, and violin, harp, and flute.
Most of my records are gone now. But as I stated I had a Rega Planar 25 turntable.
I renumber what the Consonance was now. It was the Cyber Sig 100 ( not the 15th anniversary )I liked the sound of it, just didn't like how they setup the bias. I was running Tung-sol Reissue 6550 when I sold it.
I think we can agree on some fundamental sounds like analytic vs warm or euphonic. There are certain tubes like the 6DJ8/6922 family that do indeed try their best to sound SS in our view, but perhaps transparent and correct in another's view. The 12A-7 tubes you discuss can be only be roughly divided but very roughly, mostly by gain .
I can think of 12AX7s made by Mullard in the 1950s that are 'sweeter' than 12AU7s made by Telefunken in the late 60s. So I disagree that brand and year of manufacture are not as important in determining the sound of those tubes. BTW I think of the 12AT7 as having the most protean character of them, allowing them to sound like any number of things, or virtually nothing at all.
The joy of tube rolling continues to be hearing the differences I found among these tubes, some obvious and some subtle. It cost me a lot of money. Now I am contemplating selling a lot of my collection, but I just can't get myself to do it. I would wonder where I could get some of these tubes today. I would want to buy my own tubes back. ( I really do have a silly number of Sylvania Ws though.)
Yes the gear has a lot to do with it. ARC sounds like ARC, and ARC does not sound anything like CJ. Beyond that using more closely aprroximated gear things get interesting.
You bring up some interesting points. To be sure. There are exceptions to the rule regarding my assessments of tubes. The same as the CJ Premier 11 sounded more like a SS amp, than it did a tube amp to some listeners. I have encountered one or two 6922 tubes that seemed a bit euphoric to me. But for the most part, 6922 is the nearest to SS, or as you say " transparent and correct "
Being a technician for years, and working with circuit boards. I can freely say, what employed caps, diodes, resistors, etc make a huge difference in audio, visual, and performance. The tube I used as a driver in one amp, may not produce the same desired affect in another amp. Yet the tube will still have most of it's " tonal signature " in either amp. The tube hasn't changed, the amp has. This was a tube assessment overall, not an equipment assessment.
As far as the 12A tube having the most protean character. I still think it is due to the different gains, and how the tube needed to be constructed to make that gain. Taking an audio visual technical approach. We had a saying " More gain equals more noise " The 12AX7 which is the highest gain of them all, tends to have more noise. There are exceptions. However the 12AT7 is by far the quietest ( noise wise ) of the 12A. For the most part the 12AT7 ( to my ear ) is still the smoothest sounding of the 12A in any application.
What materials that were available, and what application for the tube that was needed for could have determined what metal, and construction a company manufactured a tube back then. Perhaps that is the reason for a certain 12AX sounding sweeter than a 12AU. But for the most part 12AU is sweeter, yet smoother.
Who knows? Maybe if they manufactured a 6922, 6922A, and 6922BX, all with different gains. We would have more fun things to talk about.
I too have quite a tube collection. I decided to hold onto them, and then maybe donate them to some lucky soul at AA :)
With what kinda music you testing your equipment? CD or Vinyl?
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