My Guitar Tube Amp. Help needed with Mesa/Boogie pre

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
R

revintage

Member
Joined 2007
PRNDL said:
I would recommend experimenting ... drop the caps to 100µ and see how it sounds, then bypass the choke and test again. If it sounds better, you could order appropriate caps (20µ or so).
Click to expand...

Good thinking there. With a pair of 6L6s I would suggest an CLC filter with approximate values of 33uF-10H-22uF with the B+ for the OPT taken from after the choke.

I also recommend using a tube rectifier. If you do not have a center-tapped PT you can build a rectifier-bridge by using two silicon diodes to ground in combination with the tube.

If you want the amp to sing a stiff PSU will kill it.
 
S

spresv

Member
Joined 2007
The guy who helped me out on the project builds hi-end tube hifi amps, so that explains some things. (like the toroidals, the ps caps)

I don't have a choke available (it was originally replaced by an 120Ω/15W resistor). I'll try to lower the capacitance, and get my hands on a choke.

I don't think my PT can handle a rectifier tube. It's this one, by the way.
 
R

revintage

Member
Joined 2007
You will get to low B+ with a tube rectifier.

Initially you can go for the 120ohm resistor in combination with smaller (22-33uF) capacitors. Hook up the OPT center-tap after the resistor to get some sag when the amp is cranked up.

Rect.bridge-33uF-120ohm-22uF-OPT-1k-22u-1k(separate)-screens. But that is maybe just like AX84 did?
 
S

spresv

Member
Joined 2007
oops, sorry, my bad. read my last post, didn't make any sense :D

The way i've built it is: bridge-2x100μF-120Ω-OPT-2x100μF blah blah.

Oh, one little thing i forgot to mention, and it should be changed ASAP. I was doing some tests, and i tried the amp on ultralinear mode (the opt has ultralinear taps). Well, i forgot to switch it back... I know, i know...
 
T

ThSpeakerDude88

Member
Joined 2005
PRNDL said:
I agree with revintage -- 200µF is WAY too much for a PS cap, and 47µ too.
My Matchless-based amp has three 30µF caps and no choke.
On 10, it pretty much nails vintage Marshall sounds (i.e. Living After Midnight, etc)

ThSpeakerDude88 also has good points -- vintage Marshall players use pedals to push the amp into metal territory. I use a Subdecay Blackstar.

I've found that the best way to describe things is what famous groups and players they sound like. For instance, like you, I built my first amp without knowing what it would sound like. It turned out to be a blues machine. I spent tons of time reading articles on the internet and asking questions on forums. The best, however, was finding that the amp was basically a Matchless Spitfire with an AC-15 bright switch, except one cap in the tone stack was different. I changed that cap from .01 to .1 and voila ... blues became heavy metal!

The difficult part is your amp is completely different, so our suggestions are vague and may not apply, especially since we can't really hear your amp. Also, tube amps respond to players ... some people really know exactly what to do to get serious tone from whatever they play. They pull out killer sounds ... grunge/punk from cheap amps, blues from vintage gear, metal from high gain.
Click to expand...

I forgot to mention I used mallory 150's, which are very close to the original coupling caps used in the Marshalls. I bet SoZo's would sound even closer to the mustard caps.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom