Someone asked about techniques for increasing pre-amp gain in an amp. Here's how simple it is. Ask your questions in the comments & subscribe for more videos. universal gain stage
This was one easiest understood ways that I have seen to tweak the sound and gain, thanks so much for the info. I'd love to see more of your videos on the mods and tweaks to amps, great job.
Changing the cathode resistor does not change gain, it does change the operating point instead. Using a higher value, such as 10K, turns the stage into a cold clipper like the overdrive stage of a master volume Marshall 2203 or 2204. Changing that plate resistor to 330K will let you get into heavy metal territory.
Do any of these modifications have an impact on the power tube bias? If I was to put in a modification with different resistors for a cold clipper selector, would I have to re-bias the amplifier?
Hi Pat, I have a '77 Traynor YRM-1 that I wish to smooth the pre-amp overdrive on. It sounds a little nasty when in overdrive (ie when preamp volume on 10). It has a cold clipper gain stage with 85 volts on the 3rd stage. For the meantime I have increased this voltage to 160 to get more cleans, and use a dirt pedal for gigging. Any suggestions for us YRM-1 owners??
I would suggest a bit of a remodeling of the amplifier as its very close to a single channel tweed deluxe. I would make the PI dedicated with the first stage gain as is with the tweed deluxe cathodyne PI (it presently is a cathodyne but not complete), and move the trem circuit to the first preamp tube 2nd half......then switch it to cathode biased power tubes rather than the fixed bias and alter the trem for the cathode bias operation. Next step would be to change the 5y3 rectifier to a 5U4 or a GZ34 to bring up the power tube plate voltage and readjusting the down stream plate voltages properly...….but doing so will make the output transformer marginal, so I would change that to a 60's/70's deluxe output transformer so it can handle the wattage. It would transform into one screaming amp for a small amp...… oh I forgot......eliminate the feedback resistor too As best as I can tell this is a 1960 or 61 6G2 series amplifier.....single tone control, so it has minimal signal loss.....2 6V6's in class AB push pull
So if i was gonna add a 12ax7 in between the 2 preamp tubes, would you just copy/paste the first gain stage? Or would u want the second stage to “compliment” stage 1, by maybe boosting highs and cutting lows/mids? Thank you for the vid!
Finom1 they can be used on any tube input. You see them on power tubes. I add one to the tremolo tube if you hear ticking on some amps. They are very useful.
I like 8mfd and 10mfd ... traditional values are 25mfd for fenders and .68 for Marshalls... the smaller the value the less gain and the more treble content ...
robert barcus yes each stage works in a similar manner. The ART is in not overdoing it... and ending up with a mess. Sonically speaking ...too much salt can ruin the soup.
