Best new 6CA7/EL34?

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Best new 6CA7/EL34?

Postby joeztech » Sun Aug 21, 2016 2:22 pm

Has there been any analysis of current new production6CA7/EL34 tubes by different manufacturers to see which ones are closest to original designs introduced in the 1950s?

I recently equipped a Fisher 500C with 7591s by Tung-Sol and they are closest to original designs as far as total wattage output capability. I am wondering who makes the best 6CA7s or EL34s now.
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Re: Best new 6CA7/EL34?

Postby Geek » Sun Aug 21, 2016 3:10 pm


This is something of a "What is the right religion?" question.

They all sound different and some are a little tougher than others.

An example is if you have an amp that's really hard on tubes, say a ST-70, I wouldn't suggest dropping a quad of Shuguang in there. Even some new production Tung-Sol have been killed in the normal operation of a Grant Fidelity (Yaqin) EL34, while Electro-Harmonix do just fine.

But then in amplifiers that treat their tubes with a little more respect, a Shuguang will work fine.

I have yet to have an amp hurt a winged =C= Svetlana, BUT, there are counterfeits of those floating about (found some in the store).

Bottom line is nowadays, there is no "Best", just different levels of toughness and sonics in real EL34 and stick to reputable dealers.

-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Re: Best new 6CA7/EL34?

Postby joeztech » Sun Aug 21, 2016 3:41 pm

I am not so concerned about any typical "sound" that people say they hear, but the interelectrode capacitance and how well they match the original introduced designs as to power output level versus current capability and gain in push-pull output stages. The new Tung-Sol 7591s for instance come closest to matching the original tubes from the 1950s as to current capability and power output levels. The others now being manufactured produce less power and cannot handle the current capability of the original 7591s. I am wondering if that is also true of the current production 6CA7s and EL34s. This would require an EE with knowledge of tubes to measure sets of current production tubes from the different manufacturers.

A given set of test equipment to generate test signals at levels that can drive a push-pull output amplifier to its maximum power with less than .5% harmonic distortion and their consequent IMD would be useful along with the cathode current they can deliver at that power level. Then the highest power output just short of clipping. A specific test circuit or specific amplifier would be used for each tube brand tested over a range of frequencies so that as many parameters as possible would be duplicated for each test.

Dave Gillespie of did the test of 7591s that I found and has discussed them on the Fisher forum there.

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