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post #9421 of 9598
Quote:
Originally Posted by Sunshine55 View Post
 

I do see one possible problem. Have the pics you put up been inverted. The reason being is, in the bottom board pic, the ground for vol pot is on the left. Therefore if pot is mounted as per pic with pot on it,,,,,,,, Full clockwise rotation will turn vol down not up. I must admit,,,"Been there done that".

Thanks for the heads up...I'm going to be wiring the pot to the board anyway. I've done so many amps with the tubes showing, I thought I would try one with everything inside this time, so the pot will have to be wired off the board. Its actually a coincidence that the traces and pads are so similar to the pins on the pot...thanks again.

post #9422 of 9598

Well, I have my boards all done, just waiting on the transformers now...and some inspiration to strike on the enclosure.

 

post #9423 of 9598

Put in some Jensen Line Input Transformers.

Now I can use the Balanced XLR's on my Gungnir.  I got about a 20% boost in power.  Not measured just by feel.  This is just what I needed with my ripped LP's that are at a lower level.

 

Also have a set of Sophia Electric™ Princess Mesh 300B sometime this week.

 


Edited by sceleratus - 11/17/13 at 3:57pm
post #9424 of 9598
If you go the transformer route again, I would suggest going with CineMag. As good as Jensen, but not quite as expensive. Their CMLI-15/15B is a good choice.

se
post #9425 of 9598

Thanks Steve.

I ripped it out.  Distortion.

Done.

post #9426 of 9598
Quote:
Originally Posted by sceleratus View Post

Thanks Steve.
I ripped it out.  Distortion.
Done.

Distortion? Huh?

se
post #9427 of 9598

Yes.

The music seemed to break up and not just at high volumes.  Some tracks were better than others.  Some, the Dead, were damn near unlistenable.  I switched back to the SE (not Steve Eddy) harness and everything was clean.

 

The transformer leads are very thin, I don't know if  they were picking anything up.

post #9428 of 9598

Could you remind us what is the signal path, from the xlr output of the DAC to the grid of the input tube ?

 

This xformer can normally handle up to 5vrms (more than the gungnir can output), so it shouldn't be going bad on you. What's your volume control ?

post #9429 of 9598
Quote:
Originally Posted by sceleratus View Post

Yes.
The music seemed to break up and not just at high volumes.  Some tracks were better than others.  Some, the Dead, were damn near unlistenable.  I switched back to the SE (not Steve Eddy) harness and everything was clean.

The transformer leads are very thin, I don't know if  they were picking anything up.

That's odd. Can you check to see if there's any DC offset on the Gungnir's balanced outputs? You shouldn't have any distortion issues with that transformer with a maximum 4 volt RMS input from the Gungnir.

EDIT: Also, what's the input circuit the transformer is feeding? Any chance of DC current t flowing in the transformer's secondary?

se
Edited by Steve Eddy - 11/18/13 at 10:08am
post #9430 of 9598
Thanks for all the ideas. I'll be back home in a few hours and respond.
post #9431 of 9598

Here's the schema..

Volume POT is a 100K Ohm Alps Blue.

 

I was so PO'd I pulled the assembly last night and returned to an ALPs Blue 10k ohm straight to the driver.

 

There are a lot of connections integrating the trans.

I'd have to solder the XLR's in again, but that's not too big a deal.

I used a SchmartBoard for the connections.  The board has groups of five pads in a buss. Each corner has three pads that are bussed to ground.  I used those for all grounds on both transformers.  I did not use that for the ground lift.  I home run the ground lift to mains ground.  The ground lift worked in that there was no difference between switch positions.

 

I enjoyed the boost and thought it was great until I listened carefully.

It sounded as if the speaker driver blew.  Very rough and not just at high volumes.  The Dead are known for their recording prowess.  I put on an HD Tracks "Uncle John's Band"  It was horrible.    Although some folks might think that's normal.

 

post #9432 of 9598
Well, don't see anything that would be putting any DC on the secondaries. How difficult would it be for you to jumper those 220nF caps temporarily?

Have you checked the output of the Gungnir for DC offset yet?

se
post #9433 of 9598
Quote:
Originally Posted by Steve Eddy View Post

Well, don't see anything that would be putting any DC on the secondaries. How difficult would it be for you to jumper those 220nF caps temporarily?

Have you checked the output of the Gungnir for DC offset yet?

se

Do you mean break the grounds between L/R ?

 

I have not checked the Gungnir outputs.

Is that simply looking for DC voltage on the outputs with a DMM or scope?

post #9434 of 9598

Moving my answer to your thread to stop OTing this one ;)

post #9435 of 9598

It almost sounds like you may have an impedance miss-match. Have you tried changing the value of the 24K, maybe a bit higher value even up to 100K same as pot?

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