5687 filament question

[tone]

5687

hi frank,
thanks for the prompt response..

Does this happen on both channels?
yes, both channel.i have tested all the resistor..tot it got burn or something..nothing wrong with the resistor..hmm...funny hey..

Are both sections of the tube // (looks like it from your diagram)?
yup, both section the same..should i put a grid resistor on the input? if so what value?

BTW: do u know how to convert an AR DAC1 to non-oversampling dac?..it uses yamaha YM3623B(Digital receiver) NPC SM5803APT(FILTER), ULTRAaNALOG 20 bit dac. any idea?

 

[fdegrove]

5687

Hi,

What I don't understand is that it was fine before.

So,something must have thrown in the towel.

A gridresitor...about 1 Meg is the maximum you can put there but I doubt it will solve your problem though.

Here is what you can try: disconnect the cathode bypass cap and see if it behaves.

Something else to try is to disconnect the volume pot from the grid of the tube, just measure the voltage on the grid before and after disconnection.

What puzzles me most is that your circuit seems to work when you place the pot at the output.

Anyone with some simulator soft to help here?
Tones' circuit is on page 1.

Cheers,

 

[Burnedfingers]

Tone

Any progress on the preamp yet? Did you figure out the problem?
I am waiting to see what happens with yours because I would like to build one also and compare it to the 6SN7 linestage I just finished.


Joe

 

[tone]

5687 filament

hiyah burnedfingers:

should able to rectify what was wrong in couple of days..kinda busy this few days..sorry,..will keep u update ones i know the problem..see ya..

rgds,
tone

 

[tone]

5687 is working again!!

hi frank,burnedfingers and all..

fix the problem! the problem was me myself!! wired the pot wrongly!!..idiot!! understand the right way... wired the other way!!
the preamp is working wonderfully..!!

burnedfingers:u can build it now!

sorry for the silly mistakes!!

thanks..

rgds
tone

 

[fdegrove]

GOOD HEAVENS...

Hi,

That explains a lot of course.

I was just too afraid to suggest that.

Cheers,

 

[tone]

5687

hi frank!

ha! ha! may god and u forgive me!..

thank you frank for ur help and advice..

i o u big time..!!

i would like to do something for u..do u need anything??..i have quite a range of precision opamp with me..want some>? or do u like to have some TDA1543 dac??..i can mail it to u for free..just a gift from me to u..mail me offline..tone_ne@hotmail.com

thanks

rgds,
tone

 

[fdegrove]

i o u big time..!!

Hi Tone,

Very generous of you but thanks.

This is something all of us do for some reason or another,helping people out and seeing them succeed is the most rewarding return.

We're all happy to see you are,

Thanks again,