May 23rd, 2012, 04:36 PM
Hi, this is a purely speculative (at this stage) question. I saw the Mesa Mark 1 preamp here -> http://www.ampage.org/schems/ and wondered if anyone has built one into another amp? I'd be keen to do this but i can't find any info about mesa builds anywhere on the web. I think putting a simple low output poweramp after it would be great but I can't find any relevant info or build reports. There doesn't seem to be a Mesa forum like there is for 18watt, or JTM-45 forum (etc), or am i wrong?
May 24th, 2012, 07:10 PM
Ahh..the BF FEnder preamp with a cascaded gain stage. Put that in line with a DR power section and you have a little amp with some versatility. ONE thing, though,. I find that the Mesa Boogie thing without a post-preamp EQ section is not of much use to a rocker. AS Mesa's old manuals note...the Fender tone stack in the preamp needs to be kept under control...especially the bass...or things 'go to pieces' in the preamp. Mesa suggests that the preamp section tones be kept lower and the post-preamp graphic EQ be used to thentailor the tones without incurring overly distorted sonics. This is the same situation with vtinage BF/SF FEnders, ime and imho. When one runs the volumes up, the tone controls need to be taken down some to keep things from going topieces from over-distortion. IT is interesting to hear the difference between two players...one of whom has no idea as to how to run an early Boogie for hi-gain and one who understands this aspect of the amp.
One player will have either a thin and harsh OD sonic or an overly distorted and garbled sound..... while the other will have a fuller, more musical sound.
Wtihout building that graphic EQ post-preamp, one would need to build an effects loop so as to be able to run a graphic EQ pedal in that post-preamp position.
May 25th, 2012, 07:50 AM
Thanks Wally. I dont think I want to go through the extra work of an EQ/effects loop so that might put me off. I like the idea of the cascading gain though so I might look for something similar.
May 25th, 2012, 11:28 AM
Big equation, right? OF course, one could adjust the values of the tone caps...esp the bass and the mids....to get away from that big bottom end of the BF tone stack, but then you lose the BF sonics, right?
May 26th, 2012, 06:17 PM
It sounds worth trying and tweaking some cap values. I'll hopefully bite the bullet soon, although i'm still slightly undecided about what exactly I want to build. I'm tempted to go the opposite direction and build something with some clean headroom. I'm guessing a Mesa style preamp wont clean up that much at the twist of a knob?
I wish there wasnt so much choice about what to build :lol:
May 27th, 2012, 05:56 AM
Just a suggestion: try adding a switchable 750pf @500v ceramic cap
in parallel with the Fender 250pf treble cap, and see if you can stay with
the stock Fender tone stack values. This may make an EQ downstream
unnecessary. The 750pf cap wold be used when you go to a distorted
May 30th, 2012, 02:51 PM
James, there is nothing that keeps a person from running a Boogie MKI type of preamp arrangement in a clean mode if one understands how those gain stages work.
REdRock....adding some more high end/expandign the range of the treble control to a lower freq via that larger treble cap doesn't avoid the problems of pushing preamp gain in regard to the tone controls in these amps. Ime, one wants to lessen the gain in the preamp frequency gain controls (tone controls)....and MEsa's philosophy is to keep the preamp tone controls lower and add tones back in post-pre amp with that graphic EQ. Their manuals are specific in this regard.