Tube Amp Archive

Another option to soak up some of the gain from the input stage would be to insert a BAX tone control network after the input stage coupling cap. The Bass side of the network uses up a lot of available gain, giving you more clean range on the volume control. This is a pretty dramatic departure from ...

I did this successfully on a hi-fi amp project, using the unused 5vac rectifier filament winding on the amp's PT as the bucking winding (didn't need to install a second transformer). I wrote a post for another forum about it. See below.... -Greg "I am in the process of building a couple of cathode b...

I built a PPIMV into my Marshall 18 power amp, and I would say that it was one of the biggest breakthroughs I've made in amp tinkering. True, a lot of the overdrive in the Marshall 18 and the Deluxe does come from the output tubes, but the addition of an MV allowed me to increase the clean range of ...

I have seen many oscillations that are beyond hearing but visable on a scope, these can cause problems. Now you've got me all paranoid! Maybe it's time to switch on that old Tek that's been gathering dust on my workbench. Btw. how do you find these oscillations? My knowledge of 'scope usage is pret...

A signal generator and a 'scope of minimum 10 MHz bandwidth would be desirable for audio testing, but definitely not a requirement for guitar amp building (unless you're looking for an excuse to buy them, which I can FULLY understand :) ). All you really need is a DMM to check supply voltages and bi...

I've got a tiny room in the basement, next to the furnace. My workbench is a big, battered old oak desk that my neighbour was throwing out. It takes up about 2/3 of the floor space and is covered with projects under way and the leftovers of past projects. From what I've seen, a tidy workspace runs c...

Q: 149 -- do you get clobbered ordering things from the US, beyond the exchange rate? I thought NAFTA was supposed to make that less of an issue. I like Heyboer, fwiw. I feel like Hammond could try to keep up and they don't. Ordering from the US isn't too bad, provided you get you stuff shipped by ...

Right. I remember someone referring to a "buck" winding now. Thanks for replying.

This seems like it would be quite a handy mod, especially considering the number of complaints I have heard about Hammond filament windings giving too much voltage because the primaries were designed for 115 vac.

Greg

IIRC you can also reduce/increase a transformer's secondary voltage by wiring an unused low voltage secondary in series with the primary. If you wire the LV secondary out of phase with the primary, the secondary voltage is reduced slightly. If you wire the LV secondary in-pase with the primary, the ...