ChemMan

Tube rolling with 12AT7 and 12AX7A on MA252 preamp

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Posted (edited)
24 minutes ago, ChemMan said:

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.

Think getting a tube amp,your first .The fun is trying out all the goodies on offer .Why do you think i got a amp that only takes one tube ha ha .Would like to try a jj ec803s one day.They are not too much cash .Rabski knows the tube world big time,so cant see it being bad.Got the new gold lion 12ax7.For new tubes it,s pretty good.

Edited by mattykyuss

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Posted (edited)

@rabski @Jazid  Guys, the Teslas arrived today. Sounded great for about 30 minutes and then one channel went and died I guess.  I was out of the room for about 15 minutes playing with the little guy and I came back in and it sounded like surf.  I thought the window was open.

I switched the tubes around to the opposite channel and there was no change. Just hiss, static and no music from that channel.  I let it all cool down and tried again an hour later.  No change.

Here is what and where the order came from: https://retrostore.eu/en/d/elektronka-ecc803s-tesla-6057-1000230/?section=description

I'm at a loss.  I will obviously email the fellow my wife was in contact with, or she will, and seek a remedy.  As this is the EU we have a two week period for some remittance.

You guys have any thoughts outside of the above? I'm a bit disappointed, but who knows what could go wrong with a fifty year old tube?

IMG_3209.thumb.JPG.9afc4cfd86c04476702b377e27ad13ff.JPG

Edited by ChemMan

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Unusual frankly to have one fail, rather than be dead to start with, but not impossible.

I'd tested all the small signal tubes I have. Last week I tried a handful in the pre and one was dead.

S**t happens...

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A couple of points about the Tesla in the image: did you order an ECC803S ? If so that's what's in your pic, but the Tesla frame grids are E83CC as per my earlier post, and it is these are structurally the Telefunken equivalents. Not that there is anything wrong with their '803S, but chalk and cheese.

It is very confusing as the 'S' apparently meant Spangitter in German or frame grid if Jacmusic is to be trusted (very probably). This was the Tele original, for some reason Tesla renamed it to E83CC, and produced an 803S for no good reason known to man, and that was essentially a long ladder plate tube of no particular distinction.

Re. Failure of a tube, it's difficult to know. See what the seller has to say, they should replace them FOC. The most likely issues would be gas or cathode to heater short. The latter could conceivably be a transit related issue, gas is just a duff tube. But there is no obvious loss of gettering in either so gas is not obviously likely.

It could also be that Tesla's often have slightly thinner pins than other valves. This can make the socket contact a bit loose. Try to wiggle the valves around a bit in the socket, they should be reasonably tight, not loose.

Of course it could be the 12AX7 as well. If you have a known good valve of either (or both) persuasions it may be worth subbing (initially both) in to see if the issue resolves. If it does, you can narrow down to which valve, if neither it might be another component in the amp.

If you want me to test the valves just PM me and I'll do it.

Sent from my BLA-L09 using Tapatalk

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Posted (edited)

Good spot with the 803S. A quick Google suggests that is newer production, though I might be wrong. Sorry, apart from a few oddments, I'm more familiar with UK and central European manufactured older tubes. However: here: https://www.tubemonger.com/BLOWOUT_Slovakian_ECC803S_Tall_PL_Chrome_Flanges_p/502.htm

Comparison there with new production (which looks identical to your image) and the NOS ECC83...

Edited by rabski

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37 minutes ago, Jazid said:

A couple of points about the Tesla in the image: did you order an ECC803S ? If so that's what's in your pic, but the Tesla frame grids are E83CC as per my earlier post, and it is these are structurally the Telefunken equivalents. Not that there is anything wrong with their '803S, but chalk and cheese.

It is very confusing as the 'S' apparently meant Spangitter in German or frame grid if Jacmusic is to be trusted (very probably). This was the Tele original, for some reason Tesla renamed it to E83CC, and produced an 803S for no good reason known to man, and that was essentially a long ladder plate tube of no particular distinction.

My wife was saying she went by the description on Jac Music, and yes, ordered the 803s, because that was the model number of the Tele.  I figured something was up when I noticed there wasn't a frame around it because they made such a big deal about that aspect on Jac. 

The same Slovakian company does not have the E83CC in stock.  I've not been able to find one outside of the States just yet.  I'm avoiding anything any farther east of CZ for fear of fakes.  She has two weeks there two weeks from Sunday so we will get the replacement for the faulty tube and she and her father will continue working on the E83CC while in Moravia.

The amp itself is fine.  There is nothing wrong with the stock McIntosh tubes, I was simply in the mood for something to research and test out.

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A really good NOS  tube in Hi Fi applications that doesn't yet break the bank is the GE JAN 5751 from early 80s production .

The 5751 has a bit less gain than a typical 12AX7 but the GEs are at the same time clear and sweet with nice low noise floor.

[The Philips/ECG  branded variant is usually a bit cheaper but doesn't  have quite  the same transparency and precision as the GE .]

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Some advice: stop mucking about with this and just enjoy your amp! These are signal valves and will probably have a life of 10,000 hours or more. The original ones fitted by McIntosh will have been properly selected and tested to work well in this hybrid amplifier. Having been down this rabbit hole myself, it's easy to get completely carried away with it all.

I've just purchased an MA252. Sounds really good to me and I love the looks. The last thing I'll be doing is tube rolling. If the tubes do fail, then I'll be off to https://www.tubeampdoctor.com/index.php?language=en&mySID=H1gr7frjMVXYXI,AWZna03 who I've had many previous good dealings with. Tested and matched current production stuff. NOS valves is a minefield and a waste of time, IMO. Sure there can be differences, but that's mainly all they are; differences. Just stick with the tubes sleccted by the manufacturer and try to rid yourself of audiphile nervosa :D

Carry on!

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9 hours ago, simon g said:

Some advice: stop mucking about with this and just enjoy your amp! These are signal valves and will probably have a life of 10,000 hours or more. The original ones fitted by McIntosh will have been properly selected and tested to work well in this hybrid amplifier. Having been down this rabbit hole myself, it's easy to get completely carried away with it all.

Not necessarily true.

Any honest manufacturer will tell you that one of the reasons underlying the selection of electronic components is compliance with various directives, which rules out the use of NOS valves for a start. 

I am aware of at least two companies that have stated they ideally would have used different valves, but needed to fit new production types due to directives. AFAIK, both WEEE and RoHS have implications regarding the use of NOS valves.

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7 minutes ago, rabski said:

Not necessarily true.

Any honest manufacturer will tell you that one of the reasons underlying the selection of electronic components is compliance with various directives, which rules out the use of NOS valves for a start. 

I am aware of at least two companies that have stated they ideally would have used different valves, but needed to fit new production types due to directives. AFAIK, both WEEE and RoHS have implications regarding the use of NOS valves.

Two words: Master Yoda

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Posted (edited)

FWIW , that McIntosh tube in the photo looks like a current production  JJ ECC83s  .

[JJ of course set up using old Tesla plant and Tesla /Telefunken designs . They also still make the long plate  803s  for folks who favour  them. ]

Edited by Smokestack

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54 minutes ago, Smokestack said:

FWIW , that McIntosh tube in the photo looks like a current production  JJ ECC83s  .

[JJ of course set up using old Tesla plant and Tesla /Telefunken designs . They also still make the long plate  803s  for folks who favour  them. ]

I read this on another forum as well, that JJ makes Mac stock tubes. I'm still keen on trying the JJ Gold pin as well. They are strangely hard to find.

Here are the Philips/Mullard AT7 I am testing out.

IMG_3207.thumb.JPG.60ff342ffe3556838d12f837d8ac68ec.JPG

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Quality wise the JJ tubes are pretty much as good as any current production items.

If sourced   from a supplier who matches them carefully you should have no problems.

The Gold pin variants are factory selected tight spec examples... but good testing selection & matching  by the supplier are probably more important.

[The best suppliers are well up to speed with selecting and matching tubes for Hi Fi applications.]

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Is not all personal opinion based on preferences and the kit that said tubes are going into?

In my set up for instance, the Telefunken 801s and RCA equivalents sounded miles apart in all aspects - possibly other than bass extension.

That however was MY opinion in MY setup.

IMHO the best solution is to try to "audition" as many options as possible - and to move on the lesser models ASAP for a very slight loss. That way YOU know in YOUR system.

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31 minutes ago, Smokestack said:

[The best suppliers are well up to speed with selecting and matching tubes for Hi Fi applications.]

Any recommendations as far as suppliers go?

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