ChemMan

Tube rolling with 12AT7 and 12AX7A on MA252 preamp

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I would be staggered if the amp didn't improve with Tesla frame grids, but it might seem a little less rich initially. You should have more space, separation, and soundstage from the start however. If it seems worse then the amp was designed around valves that don't behave like model 12ax7 should. I have tested dozens and dozens of these valves (NOS and used) and have never found a new one to be off spec. Of course it must happen but...
If not, M8137 Mullards are the next choice as they are polar opposites constructionally. Bear in mind that these are end game valves for most, rare now, respected as such globally, and will only increase in value, so a relatively safe punt. Or as Rabski says, the JJ 803S for silly small money.

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Re. 5751 I have also found them underwhelming on occasion, but in my case it's difficult to separate out the sonics from the lower gain which is the only real reason to choose them in the first place. If I had level matched before comparing, &c, the differences might have gone away, but I didn't.

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Super Wammer

This is fascinating stuff, and I can see why valve users get drawn into it all.  I’ve never owned valved HiFi gear, and probably never will, but I’m very pleased such things exist.  A bit like LPs, in some ways - long superseded but offers something other sources/media don’t! 

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Posted (edited)
41 minutes ago, Jazid said:

Re. 5751 I have also found them underwhelming on occasion, but in my case it's difficult to separate out the sonics from the lower gain which is the only real reason to choose them in the first place. If I had level matched before comparing, &c, the differences might have gone away, but I didn't.

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The circuit, and the position in it.

I've actually had good results with 5751, but that's been in something like a cathode follower and swapping both tubes for 5751s. As always, what sounds great in one circuit might make little difference in another.

I'm playing (see DIY thread) with a ridiculously cheap far east PCB. A simply anode follower design that uses three 12AX7s. For a laugh, I put three Telefunken 'holy grail' valves in it. The difference over bog standard tubes is surprisingly large, though not as large as the 'value' of them. Amusingly, the second best is three 5751s, but I suspect that's because the design, such as it is, drives the second stage a bit above ideal, so dropping the gain does it a favour. Equally amusingly, a trio of early Mullards really don't do that well, though in other things I have or have tried, they were excellent.

Edited by rabski

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The other thing worth a constant reminder, is that we are not talking 'night and day' differences here, unless the original valves are truly dire or out of spec. Unfortunately, this is an area of the hobby where 'collectors' with large wallets have driven some prices up to absolutely insane levels; way above what these things are actually worth.

Good though they are, there is no way a Telefunken ECC803S is worth over $1000. Quite simply because if you're going to spend $4000 on valves, you'd get a much greater benefit from selling whatever it is and putting that money into buying something better.

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Posted (edited)
1 hour ago, rabski said:

Good though they are, there is no way a Telefunken ECC803S is worth over $1000. Quite simply because if you're going to spend $4000 on valves, you'd get a much greater benefit from selling whatever it is and putting that money into buying something better.

I appreciate that perspective more than you know. I've no idea what someone who owns the MC275 has to do and spend when they replace four KT88s, three AT7s and four 12AX7, if they want to go NOS. Based on modern circuitry some are claiming the actual valves make less and less of a difference. This makes some sense to me as well given that designers have a variety of tubes at their disposal and the devices to measure what they are trying to accomplish.

If you are interested I found this in regard to the MC 275: There are 7 preamp tubes in reissue MC 275, V1 (12ax7) – phase-splitter, V2, V5 (12ax7) – input amplifiers. V3, V6 (12at7) – output tube drivers, V4, V7 (12at7) – Cathode followers.

Mine on the MA252 are V1 & V2 12AX7 and  V3 & V4 12AT7 . I doubt this comparison tells you anything without the schematic.  I've hunted high and low for one but to no avail.

Edited by ChemMan

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1 hour ago, Nopiano said:

This is fascinating stuff, and I can see why valve users get drawn into it all.  I’ve never owned valved HiFi gear, and probably never will, but I’m very pleased such things exist.  A bit like LPs, in some ways - long superseded but offers something other sources/media don’t! 

The funny thing is, I'm not unhappy with the amp in any way.  I had a, "what happens when" moment earlier in the week and started calculating hours played.  Then the research began and this whole new world opened up and played into what I'm trained to do: research and analysis. With these guys offering perspectives on individual tubes it made the hunt easier and more fun as well.  For 160 euros I get to see if the sound stage will open up a bit and save myself the difference between 1000 euro DAC and the tubes to do the same job.  To be fair that's based on just one home demo with a Chord Qutest.  I'm probably as full of it as the next guy. :)

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Super Wammer
44 minutes ago, ChemMan said:

The funny thing is, I'm not unhappy with the amp in any way.  I had a, "what happens when" moment earlier in the week and started calculating hours played.  Then the research began and this whole new world opened up and played into what I'm trained to do: research and analysis. With these guys offering perspectives on individual tubes it made the hunt easier and more fun as well.  For 160 euros I get to see if the sound stage will open up a bit and save myself the difference between 1000 euro DAC and the tubes to do the same job.  To be fair that's based on just one home demo with a Chord Qutest.  I'm probably as full of it as the next guy. :)

I’d do the same in your shoes.  Of course, being so ancient now, I cut my teeth on swapping cartridges and turntables, and was always aware how changeable the sound was - both deliberately and accidentally!  

I may have told you this before, but when I first heard a Devialet amplifier, it was the most ‘invisible’ sound I’d ever heard.  Though I never owned one, I reckon my Primare offers some of the same agnostic sound, which has a lot going for it if you’re happy with consistency.  But I totally get the fun to had with tube rolling!

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On ‎04‎/‎05‎/‎2019 at 07:17, mattykyuss said:

Be good to hear what you think .Ive found,not all of the best 12ax7 ,ecc 83 sound the best .Depends on if your amplifier likes them ,and of course your ears.Got some nos that are expected to be up their with the best ,they dont sound great in my amp.Ge Jan 5751.Ray black plates.Amp bugle boys did not sound great in my set up .But Telefunken ecc83 and Mullard m8137 sound amazing.Lovely to play.if money lets.My amp only uses one 12ax7 tube.Went through 12 differant types ,before i found what sound i wanted.

That Mullard M8137 is a great sounding valve- even an uneducated, valve newbie  such as myself can hear the difference.:notworthy:

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23 hours ago, ChemMan said:

Let's hope it goes a bit better faster than twelve. Yet, everything I've read says you are spot on and there is no real way to predict.  I hunted thru every post I could find on every forum concerning the MC275 to see if somebody has fooled with those tubes as they are the same as mine.  My amp is so new there is not much out there about it.

Lovely amplifier you have.Do you still get the same green glow with any kind of tubes in it ?

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4 minutes ago, mattykyuss said:

Lovely amplifier you have.Do you still get the same green glow with any kind of tubes in it ?

Apparently yes as the green light comes from a light emitting diode in the tube socket.IMG_2848.JPG.d9472cb458dcbe8298181938dd314545.JPG

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1 minute ago, ChemMan said:

Apparently yes as the green light comes from a light emitting diode in the tube socket.IMG_2848.JPG.d9472cb458dcbe8298181938dd314545.JPG

Wipes drool from keyboard.Thats awsome.Cheers.

  • Haha 1

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Posted (edited)

Ok, the 12AT7s arrived today.  They are Mullard/Philips NOS tubes that were made in England.  "Made in England" is printed on the label as well as "12AX7WA Philips." 1980s date code.  The internal construction is considerably different than the stock tubes from McIntosh.  I'll post photos when the AX7 get here.

They are plugged in and running at low volumes.   I won't attempt to analyze the sound until the other tubes arrive, hopefully tomorrow, and at least level the volume between the two sets as well as standardizing warm up time.  This is going to make it near impossible for A/B testing, and there is no way to do it blind so I'm not sure I'm going to be able to offer a very substantive analysis, but I will try.

I'm loathe to even offer first perceptions as it is probably placebo effect.

Stock photo from Langrex is below.

image.png.5212156e1c188e3a539c786d110caacf.png

Edited by ChemMan

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13 minutes ago, ChemMan said:

Ok, the 12AT7s arrived today.  They are Mullard/Philips NOS tubes that were made in England.  "Made in England" is printed on the label as well as "12AX7 wa Philips."  The internal construction is considerably different than the stock tubes from McIntosh.  I'll post photos when the AX7 get here.

They are plugged in and running at low volumes.   I won't attempt to analyze the sound until the other tubes arrive, hopefully tomorrow, and at least level the volume between the two sets as well as standardizing warm up time.  This is going to make it near impossible for A/B testing, and there is no way to do it blind so I'm not sure I'm going to be able to offer a very substantive analysis, but I will try.

I'm loathe to even offer first perceptions as it is probably placebo effect.

Sure when you get the other tubes,it will all sound great.Now aleast you will have a spare set of tubes just incase.

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3 minutes ago, mattykyuss said:

Sure when you get the other tubes,it will all sound great.Now aleast you will have a spare set of tubes just incase.

Exactly my thoughts.  At some point the tubes will give out and I will have replacements.  I'm kind of psycho though, so I'll have to try Rabski's JJ gold pin EC803s just for kicks.

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