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Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
An old trick is to use two filament transformers back-to-back to take you from 115V to 6.3V and back up to 115V again. You can use the doubler on the 115V output to get 300-330V DC.
I'm just back from playing the worst gig ever with my band Although one thing happened that cheered me up: I lent my home-made tube amp (powered by two 6L6s) to one of the other bands on the bill. Their guitarist used it on the dirty channel with a Gibson SG, turned all the knobs up full, and though the sound guy forgot to mic it up at all, it managed to blast its way past the mic'd drum kit and the other mic'd up amps and we could hear it fine at the back of the 800 capacity venue. It never caught fire or blew any fuses either. Go amp!
I was going to attach a picture of it, but I discovered you can't edit a post and attach a picture later. I'll post one some other time if anyone wants to see it.
Registered Member #105
Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408
Alright, new plan. Since the 6V6 amp i was going to build only is rated for about 6W, I think I am just going to make a preamplifier again, out of this circuit from McIntosh. The only problem once again is where to cut it off- I can cut it right before the Phase inverting tube, right? I just don't know which one that is. In case you cant read it, from left to right the tubes are: 12AX7, 12AU7, 12BH7, 12AX7, then the pwer tubes. Suggestions on where yto cut it off for a preamplifier? Also, I want to "solid statify" the power supply instead of a tube rectifier. An someone tell me why there are 3 wires coming out of it, and what if anything that could be cut out since i am not using the power tube section?
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
*scratches ..and scratches head*
Why are you not going to use the first preamp I posted and make your life easy? And if it's not what you want, then just use its concepts and tweak them slightly.
Registered Member #105
Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408
See, thats the problem. I don't know the concepts really to begin with, so i have no idea what to tweak. Also, the book that I have describes this McIntosh amplifier to be really good for HiFi, which is also another switch i want to make. Also, with the McIntosh, I can try some different brand tubes in it and play around with that as well. Since the amp schematic you gave me only has 12AU7s, I can only try one brand of tubes, because that is all that I have of that type tube. Here is a different schematic, i think the preamplifier is the same, although i haven't looked very hard. The picture is clearer, too. What modifications will I need?
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12AX7 preamplifier
Although one thing happened that cheered me up: I lent my home-made tube amp (powered by two 6L6s) to one of the other bands on the bill. Their guitarist used it on the dirty channel with a Gibson SG, turned all the knobs up full, and though the sound guy forgot to mic it up at all, it managed to blast its way past the mic'd drum kit and the other mic'd up amps and we could hear it fine at the back of the 800 capacity venue. It never caught fire or blew any fuses either. Go amp! 
