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mtbguy68

How critical is matching valves in a phonostage?

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Hi all,

Alas my Sonic Frontier Phono 1 SE+ have developed a tube noise in one channel and will be hunting which tube is the culprit.

It has matched quad of Seimens CCAs and was wondering whether I can leave the good pair of tubes in and replace the tubes that's gone bad with another matched pair but not necessarily matched to the CCA. It is critical that these matched the other valves.

I was not going to buy another quad of CCA due to high prices. I was looking at trying the Seimens E88CC, Tesla E88CC GP and Brimar ECC88 since they all seems to be affordable.

Any thoughts also on the valves I listed in terms of sound that I can expect.

Cheers

Alan

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Hi Alan,

Personally i have my doubts about the need for matching in the way that you will hear it or not! I'm using Siemens E88CCand i like them very much. I thought about Telefunken E88CC in the 1st place but these prices are going up day by day. after reading some articles on the web i ordered NOS Siemens E88CC at http://www.hifitubes.nl/catalog/advanced_search_result.php?keywords=e88cc&x=4&y=7

Cheers!

Tubelover

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Hi tube lover,

I did the tube swapping on the weekend but only with matched pairs so did not hear any difference with one tube being different.

I bought a new set of Siemens E88CC from Langrex in Surrey and they sound fine to me they may not sound as fluid as the CCAs but not that far off.

BTW, have you had any experience with Langrex since they seem to be cheaper than the dealer in the Netherlands. I bought the Teslas E88CC same as on the dutch website for £10 vs €24 looks like the same tubes. The Siemens E88CC are also cheaper.

Regards

Alan

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Hi Alan,

The Siemens E88CC that Langrex offers in this moment are not genuine Siemens. These are Tesla with Siemens logo printed on it. Genuine Siemens have gold pins and a small metal label/tag inside the tube with a number on it. Also the Tesla E88CC offered at Langrex are without the gold pins, as offered on the Dutch website. So for sure you can expect a price difference there. But both are genuine Tesla from what i can see on the pics.

TubeLover

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earlofsodbury wrote:

I find it curious that tubeheads obsess over matching tubes on amps that will be stuffed full of 5% toleranced resistors and 20% toleranced electrolytic caps... :dunno:

So long as they are the same type from the same maker, made at roughly the same time, and with roughly the same number of hours on 'em, don't worry - it's not as though each channel is reproducing the same signal!

Quite so! Matching of output tubes on self-bias amplifiers makes sense, but matching tubes elsewhere is fairly pointless.

And if you're using original vintage amps, most resistors were 10%, many even 20%.

S.

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Hi tubelover,

I had a feeling that it may not be genuine but they are working fine in the SF. They don't sound that far behind the CCA so may get another 4 just as back up.I also got the Tesla Gold pins as back up for the 6922 in the BAT.

Regards

Alan

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Paul,

I take your point. But am I wrong to presume that if they are matched then the seller have at least gone through the trouble of looking at whether they are low noise or is this a misconception on my part.

Thanks

Alan

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Well tubes are matched on plate current or mutual conductance at that point you will not be checking the noise. Another thing that also comes up in my mind is what tester is used? For example the AVO testers are great....yes about 50years ago. Now they are old and mostly not well calibrated, simply because it is difficult todo and you need special (old) voltage meters to adjust them (you cannot use a modern multimeter for that). Even then these testers do not have any good noise test build in. So if you would like to have a matched or balanced tube you should start withcalibrated test equipment...and that costs money... like www.amplitrex.com

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TubeLover wrote:

Well tubes are matched on plate current or mutual conductance at that point you will not be checking the noise. Another thing that also comes up in my mind is what tester is used? For example the AVO testers are great....yes about 50years ago. Now they are old and mostly not well calibrated, simply because it is difficult todo and you need special (old) voltage meters to adjust them (you cannot use a modern multimeter for that). Even then these testers do not have any good noise test build in. So if you would like to have a matched or balanced tube you should start withcalibrated test equipment...and that costs money... like http://www.amplitrex.com

Although an uncalibrated instrument isn't accurate for making measurements of plate currents, mutual conductance etc, if you're matching tubes, then the actual numbers aren't that important, just that the two tubes should be closely matched as measured.

I don't understand why you need an old voltmeter to adjust them, you just need to match the ohms/volt of the old meter or make the appropriate allowance for the generally much higher ohms/volt of a modern digital multimeter. Anyway, anyone with an Avo valve Tester also has an AVO8, don't they? ;-)

S.

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That was my understanding, that they are matched to one another, not to some nominal value ... And that it only really matters with power valves in self biasing circuits. Even then they aren't appreciably more expensive.

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