C
chance
Well-known member
With regards to the mic-pre problems, this is from another board:
"Ok everybody, I'l speak...
First of all the modules sound fantastic. Granted 99.999% of the time I am mixing, so I haven't checked out the preamp portion, but the line amps / EQs are great.
It's interesting that all of the modules use the single ended class A output stage based on the BA283 card ( same as what's inside the N£V£ 1064, 1066, 1073 1272, etc) even the "81".
In the N£V£ 1081 the output is a class A/B push pull design.
The "81" uses a A/B amplifier in the EQ buffer amp cards, so it has a bit more of the 1081 sound.
In all cases the units produce a nice amount of 2nd and 3rd harmonic and the top end sounds sweet.
I ran some minimally miced drums through these and A/B'ed an identical setting on a popular plugin N£V£ emulation.
The sound was quite similar, but the long term impression was that when listening through the TNC..
the room that the drummer was in seemed like it was 20˚ hotter and the drummer sounded like he was smiling.... I know.. Rolling Eyes Ok?
I HIGHLY recommend that you run some pretty hot signals through these when you first get them and exercise every switch and pot. I had one or two that didn't pass signal until it got LOUD. This is a symptom of new switches with anticorrosive coatings on the contacts which are intended to self clean through use, not a problem.
Now to more serious matters. I have the same buzzing in my 81s that a few of you have reported. I disassembled the 81 and ran some tests.
Here are my findings so far:
It does not appear to be caused by power transformer induced EMI.
I ran the unit off an external supply and had the same problem.
The "73" and "84" have their inductors equally close to the power supply as the "81" and have none of these problems.
Re-routing the the audio cables (which go to the output pot and phase switch) away from the PSU made the noise floor higher.
Moving my hand in the proximity of the EQ cards made the noise floor higher.
There is a transistor on each of the EQ amp cards that is running very hot (Q4).
I suspect that there may be ultrasonic oscillations in the EQ amp cards. Every symptom I found and every other reported symptom lead me to this hypothesis.
If this is indeed the case, the solution will be much simpler than if it was power supply related. It will require a few very very small capacitors be tack soldered across a few components. I'll run more tests when I am able. Unfortunately, I don't have a working Oscilloscope here and am in the middle of producing one record and mixing two... plus having major dental work performed this morning.. ugh."
"Ok everybody, I'l speak...
First of all the modules sound fantastic. Granted 99.999% of the time I am mixing, so I haven't checked out the preamp portion, but the line amps / EQs are great.
It's interesting that all of the modules use the single ended class A output stage based on the BA283 card ( same as what's inside the N£V£ 1064, 1066, 1073 1272, etc) even the "81".
In the N£V£ 1081 the output is a class A/B push pull design.
The "81" uses a A/B amplifier in the EQ buffer amp cards, so it has a bit more of the 1081 sound.
In all cases the units produce a nice amount of 2nd and 3rd harmonic and the top end sounds sweet.
I ran some minimally miced drums through these and A/B'ed an identical setting on a popular plugin N£V£ emulation.
The sound was quite similar, but the long term impression was that when listening through the TNC..
the room that the drummer was in seemed like it was 20˚ hotter and the drummer sounded like he was smiling.... I know.. Rolling Eyes Ok?
I HIGHLY recommend that you run some pretty hot signals through these when you first get them and exercise every switch and pot. I had one or two that didn't pass signal until it got LOUD. This is a symptom of new switches with anticorrosive coatings on the contacts which are intended to self clean through use, not a problem.
Now to more serious matters. I have the same buzzing in my 81s that a few of you have reported. I disassembled the 81 and ran some tests.
Here are my findings so far:
It does not appear to be caused by power transformer induced EMI.
I ran the unit off an external supply and had the same problem.
The "73" and "84" have their inductors equally close to the power supply as the "81" and have none of these problems.
Re-routing the the audio cables (which go to the output pot and phase switch) away from the PSU made the noise floor higher.
Moving my hand in the proximity of the EQ cards made the noise floor higher.
There is a transistor on each of the EQ amp cards that is running very hot (Q4).
I suspect that there may be ultrasonic oscillations in the EQ amp cards. Every symptom I found and every other reported symptom lead me to this hypothesis.
If this is indeed the case, the solution will be much simpler than if it was power supply related. It will require a few very very small capacitors be tack soldered across a few components. I'll run more tests when I am able. Unfortunately, I don't have a working Oscilloscope here and am in the middle of producing one record and mixing two... plus having major dental work performed this morning.. ugh."
