6922 vs an ECC82.....a test.

[ashok]

I have a nice sounding single tube stereo preamp using a 6922. Today I decided to compare an ECC82 ( a low gain tube ) with the 6922. The circuit uses a +115V dc supply with 10 K resistive anode load and 100 ohm unbypassed cathode resistor. It sounds very good.
I changed the heater pin connections to supply 6.3 V to the heater of the ECC82 ( pin 4&5 strapped). The anode voltages are slightly higher than the 6922. No parts were altered.

The 82 sounds like it has more transient bite and sounds appear more distinct . Something I didn't expect as the ECC82 was not a favoured tube by some. Both tubes I used were EH . But I guess all ECC82's are not identical when they come from different companies.

Might be interesting to see their FFT's. Unfortunately I can't get that done now. I was expecting to hear some hum as the heater is ac and one heater wire had to go around the grid and cathode terminals on the tube socket. But it is very quiet.

Edit: Looks like EC8010 and Anatech mentioned that tubes with same numbers but from different manufacturers are just generic and can be quite different from each other as far as audio goes. Check out ECC82

[Zen Mod]

that voltage is way too low for proper 82 operating

[DF96]

Valve with the same number from the same manufacturer can be different, as designs evolved and some factories built them differently. If they are biased to somewhere near the datasheet values then they are more likely to behave in a similar way.

Some people reject a valve because they tried it in one circuit. Others reject it because they heard someone else rejected it. Very few valves were designed for audio. Even then people may reject them because they don't understand them (e.g. 12AX7/ECC83). The 12AU7/ECC82 is essentially two 6C4/EC90 VHF power triodes in one envelope. It is not especially linear but few valves are. It depends on how you use it.

[artosalo]

Might be interesting to see their FFT's. Unfortunately I can't get that done now.

If you have a sound card in your PC and one 10 k potentiometer+ suitable connector for sound card input, then you have all the hardware needed to do the spectrum analysis.
Just downlod free RightMark Audio Analyzer and go ahead.

The result will look like this (example):

[ashok]

".....that voltage is way too low for proper 82 operating
...."

That's what I have heard people say earlier. I can't say what the FFT looks like but the tube in this circuit really sounds splendid ! I don't have a "super, tube preamp" to compare it buy but I have heard a whole range of very high end audio and this one sounds nice. I can't say if it's equal or better than any of them unless I do an AB test and that's obviously not possible. But that doesn't matter at all as long as I like it !


DF96.."...It is not especially linear ..."
Yeah I read that too. But it does sound very nice. May not really be accurate as we never really know what the original recording sounded like ! It does sound musical .

Sounds better than my ss JLH preamp which is pretty good by itself.
Cheers.

[ashok]

[QUOTE=artosalo;2629348]If you have a sound card in your PC and one 10 k potentiometer+ suitable connector for sound card input, then you have all the hardware needed to do the spectrum analysis.
Just downlod free RightMark Audio Analyzer and go ahead.

The result will look like this (example):

-------------------------------

yup, have all that and more. I just moved to a new home and so nothing is set up so far to do that. Will take some more unpacking to do that!