12AX7A preamp tubes - ribbed vs smooth plate

Ribbed Telefunkens are a little more open and detailed than the smooth plates. I run both in a number of preamps.

preamp tubes for an amplifier

?

I only have one component in my main system that uses this tube- Lamm ML2 SET amps. I found the ribbed plate gives a little more bite to the amp, rather than making it too silky, but upline, I’m all tube.

I like this blog: https://medialux.blog/2021/03/25/the-sound-of-some-of-the-most-famous-ecc83/

Back in the day, you could buy old stock Tele 12ax7s for 10 bucks a piece. Now, the price of never used fresh old stock is ridiculous. Most people thus rely on "pulls" that test good- try to get a warranty.

FWIW, I’ve found that my bias settings on the Lamm amps are more stable with truly NOS.

My vintage system uses a bunch of 12ax7 and Tele is probably preferred. Bill Thalmann (RIP) was gracious enough to install old stock Mullard 4004s in the preamp and they sound fine in the context of that system.

Glenn Croft (RIP) told me he used buy Telefunken ECC803S for £5.95 a pop. Now they sell for $1500+

Back in the day, you could buy old stock Tele 12ax7s for 10 bucks a piece

@immatthewj amps use a variety of small signal tubes in their inputs it's also possible the OP is referring to an integrated amp.

@immatthewj amps use a variety of small signal tubes in their inputs it's also possible the OP is referring to an integrated amp.

If this is the same amp(s?) that OP was referring to a while back ago with (I think I remember him saying) 16 output tubes, I wouldn't think it would be an integrated.

It's a mono block amplifier with 8 KT 88 and 6 small tubes (  4 rectifier, 2 preamp).  And in this food chain, it's my understanding the 2 preamp tubes probably impact sound the most.  So this is where I want to spend my money.

@emergingsoul Is this the amps you have here?

Mike

"It's a mono block amplifier with 8 KT 88 and 6 small tubes (  4 rectifier, 2 preamp)"

Huh?

That's a most unusual topology.

What brand is this? Dual rectifiers for each channel?]]

I doubt there are 4 rectifiers that doesn't make any sense.

@jond 

You got lots of cool stuff. Maybe you have too many tubes in boxes. Why you have so many tubes?

4 12AT7 tubes. no clue what they do Beyond rectify. I know rectify transforms AC to DC and why you need four tubes to do that, dunno.

Hey emergingsoul I very well have too many tubes in or out of boxes that said the 12AT7 tube is not a rectifier tube.

"4 12AT7 tubes. no clue what they do Beyond rectify"

Your amp is SS rectified, not tubed.

2nd gain stage/phase splitter? Just guessing.

It's a mono block amplifier with 8 KT 88 and 6 small tubes (  4 rectifier, 2 preamp).

I assume the "2 preamp" tubes are the amps input tubes or driver tubes?

. . . ohhh, so they are MC9011s? I just did a cursory read on them--interesting amps.  Anyway, Mac is calling the two 12AX7s the signal tubes for the amp.  Which is not what I would call a "preamp tube"  (I would call a preamp tube a tube in the preamp) but I guess it doesn't matter what you call it.

I wonder what the 12AT7s are for?  Inputs or drivers into the ss section?

OP

I’m 75, until last year, I thought rectifiers were rectifiers, nothing to do with the sound.

My friend had a new Phono Preamp built by .... she included new 'broken in' tubes as well as some spare used tubes.

We listened here, changed tubes, small subtle differences, ’prefer’ not ’better’ differences.

changed rectifier, holy smokes was I surprised how easy it was to hear the difference. ’better’ was obvious.

@elliottbnewcombjr Im also under the impression that a rectifier is a rectifier, so now I’m curious as to what you have found by switching rectifier tubes and what your are now using that make the difference. I have McIntosh MC30s and have been using NOS RCAs. Let me know. Thanks.

I read a lengthy comparison written years ago about 12AX7s and the writer felt that the 5751 gave a more engaging presentation.

The 5751 is a lower gain, quieter version of the 12AX7.  So I tried a Sylvania black triple mica NOS and I agree with him.  I find I lose interest in the music easily, even with a $275 12AX7, compared with the 5751.  With the 5751 in my 300B integrated amp, I can’t stop listening.  Have to force myself to get up and walk away.

And I don’t notice any difference in gain.

GE Black Plate 5751 are great tubes and I've used them a lot over the years. Late 60's Mazda 12ax7 WA silver plate however are the finest small sig tubes I've iused in my current preamp. Have run through Amperex, Tele, Brimar, Mullard & I find the  Mazdas are legit - right in my lane. Just my opinion.

dinov

I don't think the answer (I'd need to ask my friend, we didn't make notes), and it would not be applicable to other phono/pre/amps in any case.

I would search for 'rectifier tubes' see what info comes up. perhaps ask Brent Jesse audiotubes dot com for advice.

If you find a good article about rectifier tubes, please let us know.

An amplifier modulates the power supplied. All things being equal, the better the supply, the better the sound. 

I thought rectifiers were rectifiers, nothing to do with the sound.

It was only a matter of time. Surprised it took this long. 

As I understand it, women seem to have a preference for the ribbed tubes. 😁

I too am shocked at the differences between rectifiers, including differences between direct-heated and indirect heated rectifiers. Fun to roll in my Woo headphone amplifier.

BTW, this is the first I am hearing of Bill Thalmann’s death. I met him in 1974 when he sold me my second pair of Advents while he was a salesman at the old Atlantis Sound in Falls Church, VA. The next year he very kindly helped me build an Ampzilla amplifier kit. I last spoke with him last fall as he was closing his shop. What a wonderful guy…it’s very sad news.

That is very sad new indeed I knew Bill had been ill what an audio legend may he RIP.

Sorry to be the bearer of bad news re Bill Thalmann. We took the equipment he was going to restore for me down to Virginia on our way out of NY when we moved to Texas in January, 2017. Met Bill, got a tour of the shop, he touched base while he was doing the work- restoring my old Technics SP 10 mk I (which I bought new in 1973), a pair of Quad II amps (I found the glass, including real GEC KT 66’s!) and a McI MX110z which I bought from a vendor online and had shipped directly to Bill for restoration. Sounds wonderful with my old Quad 57s which were also restored (by Kent McCollum). This is my "vintage" system in the front parlor. (Main system is in a dedicated room upstairs)

This system is a close approximation of what I ran in 1975, except I used all ARC stuff then (SP3-a-1 and Dual 75a). I still have the amp and a fresh complement of tubes that I bought from ARC back in the aughts. At some point, I’ll bring the Dual 75a back to life--it would probably play if I fired it up, but should be recapped and checked.

I didn’t know Bill well, but I really appreciated the care he put into his work and he was a gentleman in every sense of the word.

On rolling rectifiers, the Allnic H-3000 and its bigger brothers (phono stage) is very susceptible to sonic changes owing to the rectifier. I’ve tried a bunch and have several more that I’m sitting on. I did secure a NIB old metal base Mullard (really a Philips-Miniwatt from Holland)--a grail tube. It has profound bass, but at least in the circuit and system, lacked the air of my preferred GEC u-52.

That GEC tube is not a direct equivalent to a 5AR4, but works in the Allnic. It has a "cup" base- I have a couple of them, a brown base and a black base-which I understand may be earlier-or intended for industrial use. Not an easy to find tube in unused condition.

@whart Mullard's have no top end!

lacked the air of my preferred GEC u-52.

The Mono amplifier uses 4 12AT7 tubes and while four seems a bit much for rectifying (ie converting AC to DC) maybe two are devoted to this worthy cause and then it leads to the question what are the other tubes used for . I thought preempt tubes were a way to describe use of this tube within an amplifier (ie taking the week analogue level signal from the pre-amplifier and turning it into a stronger line Signal) and is this also considered to be a signal tube?

I thought preempt tubes were a way to describe use of this tube within an amplifier (ie taking the week analogue level signal from the pre-amplifier and turning it into a stronger line Signal) and is this also considered to be a signal tube?

I’ve never made any claim whatsoever to be an audio/electrica/tube guru, so maybe I’ve been wrong all these years, but I always thought of the tubes in a preamp (or the preamp section of an integrated) as being the "preamp tubes", and then all of the tubes in an amplifier, including the smaller input or driver tubes, as amplifier tubes. For example: In my amp, I have always considered the pair of 6922s and pair of EL84s that are in front of the dozen EL34 output tubes as all being amplifier tubes. And I have then also considered the six 6SN7s in my preamp as the "preamp tubes." But like I said, maybe I have been wrong about that.

As far as "signal tubes", technically, I guess they would be any tube in the signal path? Although I guess that when someone says "signal tube" maybe we usually think of the smaller tubes in the front of an amp or the tubes in a preamp?

I don’t know for sure, and here’s to hoping someone will educate me, and as I typed previously--I guess it doesn’t really matter what you call them (although it may be confusing if we all call them by different nomenclatures).

I grey up in the 70s and early 60s type smooth plate was more preferred.

siemens isat least on paras Tele  . 50-60s preferred for both,  early 70s, no 80s.

check Andy at vintage tube services. The most knowledge on tubes period !

Brent Jesse audio has been around also ,as well as vacuum tubes  dot net 

I have tried Smooth plate and Ribbed plate Tele's in my CAT preamp, much prefer the Smooth plates. The Ribbed plates are a little brighter and tend to be less resolving. Perhaps in a different position, or component, this might not be the case??

"Glenn Croft (RIP) told me he used buy Telefunken ECC803S for £5.95 a pop. Now they sell for $1500+"

You can spend a lot less than $1500 each for a pair of Telefunken long/smooth plate 12AX7s tested and strong.  In fact, you can even get a pair for $125 right here on Audiogon if you look for them.

@mike6972 Telefunken ECC803S is not a 12AX7.