Tube Amp Archive

The problem is the transformer i'm using it dosent have a 60v tap so i took a feed from the mains and droped it down to 60v buut that ruined the waveform so i've shelved the project till i get chassis,it & ot. I have already laid boards out ready.
Thanks Dino

Hi checked the voltage on pin 5 and found it to be -2.3VDC so i removed the 27K resistor and now its -41.4VDC so im going to fit a 10K pot so i can fine adjust it because the bias has now dropped to 2MVDC and ideally i want it around 37MVDC so just some fine tuneing and my prototype will be ready fo...

Hi guys just a quick update on my Dumble 70's build fixed the problem with the squilling it was the ratio pot on the overdrive channel i had wired the pots backwards so they were full on and not off as i thought so the amp was feeding back in clean.... :D :oops: :lol: I've now got the amp running an...

Does anyone have any experience with multi sim program have used it for testing valve amp designs but they won't run...Have tried marshall and fender designs none work on program and i'm sure the design is right.

Can anyone offer some help or suggestions

Thanks for all the help the new diagrams are completeley diffrent from the one i used will try these and let you all know.......

THANKS THANKS THANKS

The voltage is 1 or 2 Volts off about 458V instead of 460V all of the voltages are very close to what they should be but i'll check them monday at let you know the exact voltages

Yes i tried swapping the leads and other ideas but still the same.
Thanks

Hi i'm fairly new to amp garage and i built a 70's dumble from diagrams i got of the internet but i cant seem to get it to work i've followed the diagrams and checked it over a few time but always have the same problems am i missing something or are the diagrams wrong:: :roll: the problem is strange...

These are the diagrams i used scoured internet to find missing vales is this diagram correct or am i going mad.............. the noise is back

Thanks Dino

Thanks for all the help that formula is very helpfull managed to fix the weird noise problem was my messy wiring now got it sort of working and im on the way keep you updated

Thanks tried that with only power amp on and no noise but when i reconnect the preamp its back also whats the bias voltage supposed to be i think -55V but may bee wrong.....

Thanks for the help

Hi dont know if you guys can help me but i have built a 1970's style Dumble and when i take it out of standby it makes weird squieling sound...
I've gone through the diagrams and the circuit but cant find any mistakes..;....;....

HELP