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Topics - SECONDandBOWERY

#1
What is the key to making a transparent preamp?

Let's say it's for bass.  The point is that no matter what bass you plug into it, it still sounds like that bass.  A P-Bass sounds like a P-Bass, a Jazz Bass sounds like a Jazz Bass, and Derek Smalls's doubleneck BC Rich mockingbird sounds like Derek Smalls's doubleneck BC Rich Mockingbird.  No fancy sound alteration, just the true natural sound of the bass but loud enough to pump it thru a poweramp.

I'm assuming that the fewer parts in the signal path, the more transparent the circuit will be, so a minimal amount of amplifying untils such as transistors and opamps as well as a minimal number of knobs should be used.  Am I right on this?  If not, please tell me what I'm wrong about/missing/forgetting/confused about.

Thanks!

Rock'n'Roll,
--Andy
#2
Amplifier Discussion / Push-Pull Amps
June 03, 2006, 12:50:39 AM
Is it possible to arrange op-amps in a push-pull configuration?  Obviously there'd have to be a phase splitter but apart from that, how would this be done?  I understand about how tubes work in push-pull, but I've never seen op-amps like that.  I imagine it wouldn't be too different, but I'm just curious.

I think the op amps would have to be biased differently.  70% idle current, not 100%, right?  That would put it into class AB instead of class A, which means it could be configured in push-pull.

Am I looking at this the right way?

Rock'n'Roll,
--Andy
#3
I've attached a schematic of the Line Out used by Marshall on their amps with XLR outputs.  How the do I apply power to this thing?  There appears to be voltage at VB, but the last time I checked you need a voltage and then half of that voltage to properly bias a opamp (I'm thinking of using two TL072's for the opamps), right?  So someone explain this to me...

Thanks!

Rock'n'Roll,
--Andy
#4
Basically, if I'm looking for a schematic for some sort of Solid State doo-dad, these are the sites I check.

Geofex, the Guiter Effects Oriented Web Page (Just click the schematics link in the left hand column):
http://geofex.com/

Aaron's Stompbox Forums Selected Schematics:
http://www.diystompboxes.com/pedals/schematics.html

The Free Information Society Audio Schematic Archives:
http://www.freeinfosociety.com/electronics/schempage.php?cat=1

Jack Orman's AMZ Schematic Collection:
http://www.muzique.com/schem/index.html

If it's not on one of those pages, chances are it doesn't exist.

Rock'n'Roll,
--Andy
#5
Hey Guys!  This is my second post here (my first was about 30 seconds ago).  I own a Peavey Rage 158 and I absolutely love it.  It sounds perfect for the kind of music I play, but it's just not loud enough!  So I figured that I would try to build a Rage 158 but with a more powerful power amp.  Then I said to myself, "If I'm going to build in more power, why not build in an entire second channel?"  So now I'm thinking, two complete Rage 158 preamps (each with a clean volume control, distorted pre-gain, distorted post gain, a switch to choose between clean and distorted on each channel, each with it's own TMB tonestack, and a switch to choose between a vintage or modern countour) running into a much more powerful power amp.  The power amp must retain the original sound, just louder!  So, should I just copy the output stage of the Rage 158 and run two or three or four of those in parallel?  Also, what power supply mods will i have to make?

Here's a link to the schematic (without modern/vintage switch):
http://www.freewebs.com/andrewrovner/Peavey%20Rage%20158.pdf

Thanks in Advance!

Rock'n'Roll,
--Andy