 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.39.44.163
In Reply to: RE: Suggestions for budget amp posted by badman on March 14, 2008 at 15:09:27
Hi Guy!
This is easy, as I KNOW you can DIY. :>)) What Fisher and Scott did, you can do too. Small signal circuitry that drives EL84s and 6V6s also drives 7591s. PP ultralinear mode 7591 finals will yield approx. 30 WPC. Use the 12AT7 based splitter driver found in "El Cheapo" (schematic attached). Edcor (www.edcorusa.com) model CXPP60-8-6.6K O/P trafos will do nicely. A combination of grid and cathode bias will be used on the "finals", as that safely permits the use of 330 KOhm 7591 grid leak resistors.
NJ's own AnTek provides the power trafo. Use their model AN-3T325. The trafo's 6.3 V. winding will power all 6 signal tubes. Voltage multiply the 12.6 V. winding to obtain the negative voltages needed for CCS operation and O/P tube bias.
EMail me for more details, if you're interested.
Eli D.
Follow Ups:
Thanks Eli:
Thinking about it :) kinda worried about building though, since I'm not in jersey anymore, though my tools are. I'm building a temporary setup in my temporary house here, to tide me over until the big dogs come from out east.
Where's "here", these days?
What are you using for speakers? Did you apply Joppa's 102 dB. rule to your situation?
The folks in this hobby are scattered world wide. There may be another DIYer 'phile nearby to help you out in building. It can't hurt to ask.
Life has its twists and turns. You left NJ and headed West. I moved from NYC to Plainsboro, which is just NE of Princeton.
Eli D.
Here is Southern California (Orange County). Right back where I started, but older and better paid.
Speakers are not complete, they're a 2 way open baffle, with some neat tricks including floor loading and some baffle stiffening techniques, a JBL 12" (123A, vintagey alnico, superbly nice woof used in the L100) and fostex FF85k. First order series network at 500Hz.
the 102dB rule.... well... 15W would get me there. Don't need a lot more because the woofer's going to be at risk for overload, having no cab to damp it's motion around and about Fs (which is 24Hz and .5Qts, so quite a bit of back 'n forth). Concerned enough about that limiting my ability to crank it up a bit that I ordered one of the harrison labs in-line filters. Easy enough to calculate, but this one's convenient in that I can 'rumble filter' at 5Hz increments, so find the best balance between attenuation and max output. Don't want a driver playing midrange trying to do 15
hz :)
My baffle models up with very solid response to 40Hz.
So I don't need a lot of juice (in the bass it's especially efficient, like 92dB 2.83V/M @ 50Hz), and the room is small.
I may even have to attenuate the bass a bit, which is a pleasant problem to have with an open baffle. A shelving filter of some sort will likely be necessary, but no way to be sure until I wire 'er up. I'm actually quite okay with a 'saddleback' response profile, since I listen at modest levels and so it's like having a built-in 'loudness' contour.
Anyway, thanks for the recc!
Jeff
I think you could make some $$ for yourself if you did up a nice little power supply PCB for the El Cheapo. You could throw the B+, B-, and maybe even the CCS all onto one board and really simplify the build.
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
