Peavey Rage hates buffers - ???

Tube or solid-state, this section goes to eleven!
Post Reply
User avatar
greigoroth
Breadboard Brother
Information
Posts: 97
Joined: 09 Dec 2010, 10:59
Has thanked: 3 times
Been thanked: 12 times

Post by greigoroth »

I recently finished redoing me pedalboard and included AMZ's JFET input buffer and a GGG output buffer. When running through a H&K Cream Machine and 1x12 the rig sounded great. But running through a Peavey Rage 158 it distorted extremely unpleasantly when digging in and using higher output pickups. The buffers have plenty of headroom, and the distortion is only present in the Peavey. I noticed no apparent volume increase when I bypassed the buffers.

What could be going on here? Is there a mod I can perform on the Rage to make it, um, rage less? :scratch:

The Peavey Rage schematic can be found here http://www.freeinfosociety.com/electron ... age158.gif and the buffer is at AMZ http://www.muzique.com/schem/eagle.htm

User avatar
phatt
Transistor Tuner
Information
Posts: 1217
Joined: 04 Aug 2010, 05:17
Location: Morayfield SE Qld AU
Has thanked: 8 times
Been thanked: 338 times

Post by phatt »

At a guess your signal swing is now rather large and the Rage was not meant for really big signal input.

Some series resistance at the input might help to tame the situation. Other here might have more experience with such stuff.
Phil.

User avatar
Prostheta
Solder Soldier
Information
Posts: 186
Joined: 04 Jul 2011, 09:19
my favorite amplifier: Trace-Elliot AH300-12
Location: Pori, Suomi
Has thanked: 11 times
Been thanked: 5 times

Post by Prostheta »

Odd. No apparent volume difference implies no change in signal swing. Could it be DC offset?
"People demand freedom of speech as a compensation for the freedom of thought which they seldom use" - Søren Kierkegaard

Image

User avatar
phatt
Transistor Tuner
Information
Posts: 1217
Joined: 04 Aug 2010, 05:17
Location: Morayfield SE Qld AU
Has thanked: 8 times
Been thanked: 338 times

Post by phatt »

Prostheta wrote:Odd. No apparent volume difference implies no change in signal swing. Could it be DC offset?
Good point,,,I missed that :thumbsup
but I tend to think these little Amps struggle with anything big at the input.
Phil.

User avatar
greigoroth
Breadboard Brother
Information
Posts: 97
Joined: 09 Dec 2010, 10:59
Has thanked: 3 times
Been thanked: 12 times

Post by greigoroth »

Yeah, it's really, really odd. Especially considering the FET buffer is slightly less than unity.

User avatar
phatt
Transistor Tuner
Information
Posts: 1217
Joined: 04 Aug 2010, 05:17
Location: Morayfield SE Qld AU
Has thanked: 8 times
Been thanked: 338 times

Post by phatt »

Maybe checking the pinout on the fet might shed light on the problem,, that can easy happen.
Phil.

User avatar
greigoroth
Breadboard Brother
Information
Posts: 97
Joined: 09 Dec 2010, 10:59
Has thanked: 3 times
Been thanked: 12 times

Post by greigoroth »

I'm pretty sure it's not the buffer as it happens with my IC buffer, and even when using the Cream Machine as a preamp. ??
No great problem, I'm just using it as a practice amp, but I'm really intrigued as to what's going on!

Post Reply