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    Building, troubleshooting and testing of these amplifiers should only be
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6DJ8 / 6922 tube?

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Nordic

Nordic

Member
Joined 2005
users.tpg.com.au/users/gerskine/dxamp/
IMG_0666_1-1.jpg

from a desk drawer I think the last one is a JAN.
 
S

Sherman

Member
Joined 2004
trifidmaster said:
I have used the JAN 6922 as a preamp and also as a phase splitter for my PP amp.
In my experience the JAN 6922 need "LOTS" of current for a good sound - I have experimented with different current values.

...

Indeed It might "sound" that the 6922 will deliver less bass.

I have never used the 6DJ8.

trif.
Click to expand...

Tifid,

How much current do you find they need to sound their best? I've tried them at 8 mA and 12 mA since that's what I was running the 6N1P at when I tried plugging in a JAN 6922. (Also tried a new 6922 with the same result.)

In my case I heard a lack of bass so I used test tones on a CD and my SPL meter and found that there was indeed a drop-off of bass. Rather dramatic as well. -3dB (compared to 6N1P in same circuit) was 100 Hz. It went south rapidly from there to a -18dB by 40 Hz.

I wonder if 15mA might make a difference?
 
trifidmaster

trifidmaster

Member
Joined 2006
Sherman,
I will re-check - as I did many experiments - but if I recall, I think I am at 14.5 mA. The higher current will shorten the tube's life, but I had to go so high to get a good sound.

I believe your SPL meter is "flat enough" - your numbers are indeed "dramatic".

Definetly, the 6922 is not giving any "SMILE" type of curve.

Currently I am working on a full tube professional summing box and I am using lot of 6N1Ps - the very 1st listening tests are promising - but I am far from making any serious statement.
BTW: I am "testing several topologies with the 6N1P.

trif.
 
S

Sherman

Member
Joined 2004
trifidmaster said:
Sherman,
I will re-check - as I did many experiments - but if I recall, I think I am at 14.5 mA. The higher current will shorten the tube's life, but I had to go so high to get a good sound.

I believe your SPL meter is "flat enough" - your numbers are indeed "dramatic".

Definetly, the 6922 is not giving any "SMILE" type of curve.

Currently I am working on a full tube professional summing box and I am using lot of 6N1Ps - the very 1st listening tests are promising - but I am far from making any serious statement.
BTW: I am "testing several topologies with the 6N1P.

trif.
Click to expand...

In all probability the issue is less with the tube than with the specific circuit I tried it in. Something there it didn't like. I built a PP EL84 amp that I originally designed with a 6N1P in mind as the voltage amp and a JAN 6922 sounds excellent in that one.

OK, that got me thinking and I just went and check the PP EL84 amp. Guess what? The 6922 in it is at 13.5 mA! Maybe 13 to 15 really is a 'sweet spot'.
 
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