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In Reply to: RE: two questions about 45 and 300b..............thanks posted by bouncy ball on April 03, 2014 at 08:52:21
http://www.vt52.com/
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I have 3 Sylvania VT-52s. It appears from the data available, they have the same operating points as the 45. From what I have read, the Western Electric VT-52 can be run harder.
Jeff,
What is your experience. I ran the Sylvanias as prescribed... I didn't have the right speakers for the application at the time.
Stuben
Also called a "special 45" I once briefly owned the largest cache of them in the world, 137 pieces of NOS Hytron and engraved Western Electrics. Paid $5.00 for all, sold them for $6,000.
ALL vintage DHT tubes have "V" or "W" or "M" shaped filament structures. Due to their asymmetrical spacing, it is possible to outperform them today. A modern DHT can have symmetrical filament spacing, and larger more powerful cathodes, and these soncially "creme" vintage DHTs.
Examples would be the DHT filament structures on earlier AVVTs, current production EMLs, or, the cost-performance bargain of the decade, a JJ 2A3-40.
Its hard to beat a 2A3, especially these new better designed ones.
Have fun,
Jeff Medwin
Just to clarify a couple points you are wrong about:
There were vintage DHTs that had symmetrical filaments like the AVVT/EML filaments (where do you think they got the idea?). Primarily, the "single-plate" 2A3, which had what is known as the "harp" filament. The 1608, a high-mu version, also shared this design, and there were others.
Also, re: "I once briefly owned the largest cache of them in the world," - really? you were aware of every other VT52 in the world, and who owned them, and when? Right.... Didn't think so. So don't make stupid blanket statements like that, it undermines your credibility.
-Ed
Yes, of course I am aware of the original harp filament Ed, hard to source these days.
The largest cache was an estimation of George Fathauer, of Antique Electronic Supply. Not too bad a reference, he had some experience.
Jeff Medwin
Today you'd get a lot more for this sale
I heard a number of 2A3 amplifiers
nice but there are better in my opinion
Amplifiers based on VT52
I know two or 3 designers that deals with that tube:
http://www2.117.ne.jp/~y-s/A-010-e.html
http://www.6moons.com/audioreviews/roadtour16/roadtour16.html
http://db.audioasylum.com/mhtml/m.html?forum=tubediy&n=47020&highlight=45+circuit&search_url=%2Fcgi%2Fsearch.mpl%3FForumSelect%3DSelected%26author%3DMurph%26user_id%3D9865%26sortOrder%3DDESC%26
I have AVVT 2A3 meshplates and the EML 45 hard plates that will play in the same 2-stage. If I make one mono block 2A3 and the 45, and swtich channels a few times, I prefer the 45 sonically. Both are top tubes.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
Hi,
The modern EML 45 will probaly have multiple symmetrical filament runs, with a greater cathode radiating area, I would think. It should easily outperform a vintage Type 45.
SE amp execution and design is the weakest link, not the DHT differences.
Jeff Medwin
Jeff,
You put great importance on the geometry of the filaments yet do not discuss the metallurgy of the tube construction, which I suspect plays a greater role in the sound of one tube manufacturer versus the next. The EML tubes I've seen all use gray plates while most NOS 45s are black plates.
Donald
I'm not sure why the geometry of the filament would matter as long as the electron cloud covers the needed area.
The electrons do not flow straight from the filament to the plate.
If they did then I could see the focus on the filament geometry.
But, AFAIK, they flow from the filament to become part of the the cloud and then to the plate and in a healthy tube the cloud is always bigger than it needs to be to keep up with the demand of the plate.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Donald,Please let us know what you believe the differences are between Gray and Black plates, regarding metallurgy !!
True, I only discussed one aspect, symmetry and size of the cathode. THAT is where most of the major differences are between the best modern and dinky vintage tubes.
I envision the cathode as the start of the DHT tube, much like the power supply is the start of the audio amp.
You addressed metallurgy ( actually "color" ) of the plate, how about metallurgy of the other two thirds, the grids, and the cathodes??
Think Jac isn't up to snuff in optimizing ALL areas???
'Ever had a chance to A-B EML 45s versus a NOS black plate 45 ??? What was that like for you?
Jeff Medwin
Edits: 04/06/14
Hi Jeff,
I'm sure the metallurgy of all 3 components influence the sound. In the past I've compared gray and black double plate 2A3s, both RCA branded, and they sound different. In general I preferred the sound of the black plates.
How can you say with such certainty that the symmetry and size of the cathode is responsible for the most differences? That's not obvious to me and doesn't correlate with what I have heard.
I have not A-B compared EML versus NOS American 45s, but I have compared EML 2A3 meshplates versus many other new production and NOS American units. One is not categorically better than the other and I hear strengths in both.
Donald
The EML mesh WILL sound different than the solid plate EML, or a JJ 2A3-40 solid plate. I am not so sure you get a true picture comparing a "meshie" to other solid plate 2A3s. A meshie is a different presentation.Also, the better the 2A3 amp, the wider band it plays ( not necessarily measures, but how it plays the speaker voice coil ) the easier it is to hear these differences. My buddy Dennis Fraker easily makes the best there is in 2A3 amps these days IMHO, so, we can get a handle pretty well on these tube performance differences, modern single plates with large symmetrical cathodes versus dinky NOS biplates with asymmetrical filaments. You should have him build you a pair of 2A3 SE DC amps, to have as your reference, while you can. It will easily be the best audio purchase you will ever make, IMHO.
Jeff Medwin
Edits: 04/07/14 04/07/14
I've listened to the EML solid plates too but spent more time with their meshplates, finding their sound more preferable to me of the two.
Thanks for your amplifier recommendation, but I'll keep enjoying what I have ;)
Well, transconductance depends largely on cathode-grid spacing, or at least the length of the electron path within that spacing. Since this is the smallest critical dimension in the tube, it is not unreasonable to ascribe a majority of the variability of performance with operating point to this variation. And in fact the curves of the modern designs are especially linear. Whether curve linearity is the major influence on subjective sound quality is I believe unknown and unknowable.
I personally am more suspicious of the cathode substrate and coating. It is reasonably well known that excess noise increases with cathode current, while Johnson noise decreases (because of increased transconductance) - hence the cathode size affects the current density and you might reasonably expect a quieter tube to have a larger cathode, all else being the same which it never is. Alternatively, (Jeff will love this) you might reasonably expect a tube to be quieter when run at a lower than maximum current.
The other known effect is that of the cathode substrate (the filament wire itself for DHTs). It's traditionally nickel, and certain impurities (silicon for example) are known to result in eventual formation of cathode interface, increasing noise. Silicon (again, just an example) also makes it easier to "form" the cathode, making it cheaper to manufacture tubes - no free lunch.
I have not even touched on the cathode oxide coating, about which I know practically nothing. But speaking as an engineer, I am certain that the things I don't know are even more important than the ones I do!
It's also "well known" that increasing the current lowers the Rp and as a result, lowers distortion and raises power. Can anyone hear the "extra noise" of a 2A3 run at 75ma compared to 43ma (except Jeff) ? Not "sound quality" but NOISE ? ? ?
It's a great question, but as far as I know there are no studies or measurements to guide us. Perception of low-level noise in music is not at all easy to understand; it often is perceived as something else like grain or listener fatigue. Digital studies have shown that the character of low-level nonlinearity is perceived even with large amounts of masking randomness, for an example of something that "should" be too small to hear.
I agree, there are several more plausible explanations of what Jeff hears - but there is not enough data available to completely discount this one.
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