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Old 21st July 2002, 12:38 AM   #1
Gabster is offline Gabster  Canada
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Default Mesa Boogie DIY!

Hi,

I recently found schematics for many mesa boogie guitar amplifiers (here) . The one I'm the most interested in is the dual rectifier solo head (one of my friends has one and it is amazing). All the schematics seem there, the goal is to build a replica.

I have two major concerns:

1) Is that kind of project doable? The guy on the site seems pretty sure it's not a good idea (read comment in red at the top). I think it's just a comment to avoid to receive 100's of emails about this. Using the schematics we can do a lot!

2) Is it possible to find the transformers? Is it easy to get these as replacement parts from mesa boogie?

The bottom line:
Is it people out there who ever succeeced in that kind of project and/or would be interested to invest time to give it a try? I'm seeking for people who have knowledge and would be active members of the thread "The DIY Mesa/Boogie project".

regards,
Gabriel
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Old 22nd July 2002, 07:33 PM   #2
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Hi Gabster,
1) Yes is possible to build a clone: I built several
2) The parts are widely available. And also not as direct replacement.
Ask me more informations if required.
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Old 22nd July 2002, 07:57 PM   #3
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Hi,

Would like indeed. I'm busy for more than a week now on a high-gain SE EL83 guitar amp but I keep having problems with hums, buzzes and crackles... Do you have a website?



gr,
Thijs.
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Old 22nd July 2002, 08:12 PM   #4
dice45 is offline dice45  Germany
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Quote:
...high-gain SE EL83 guitar...
Are you sure it is not EL84 or EL86 ?
EL83 is an odd number and would have non-linear, regulating-purpose transfer characteristics.
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Greets,
Bernhard
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Old 23rd July 2002, 02:48 AM   #5
Gabster is offline Gabster  Canada
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I'm happy there's some interest.

wasp, what was your tactics when building clones? Did you only used the schematics? What did you build?

I had the idea to find a cheap non working dual rectifier (I hope I can find one), use the original PCB as a reference for the layout, built the clone, fix the amp and sell it to repay what I've built.

With the schematics and the original PCB it should be easy to end up with a good replica. Furthermore, I would also try to build a box like the real thing...shouldn't be hard, simple design.

tschrama, sorry no website. I'll update this thread as soon I have something.

now, let's see if I can find what I need...

regards,
Gabriel
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Old 23rd July 2002, 02:48 PM   #6
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Hi Gabster,
I have built 4 JTM 45 Marsciall, 2 Showma Fonder, and various little SE guitar amp.
The layouts are drawn by myself or, for the Showma, using the original one.
If You gain experience with tubes all the amplifier are laid out the same way.
The hard thing in building amplifiers isn't the layout but: the cabinet, the finish, the chassis, the covering and last but not least the sound.
To acquire knowledge I think it's better to start building little things: small preamplifiers o little se, with low gain.
Wasp.
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Old 23rd July 2002, 07:23 PM   #7
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Oops...

I mean EL84 (not EL83), a small 12watt penthode, used alot in small guitar amplifiers. I got rid of the hums and buzzzis.. today I learned:

(1) allways give the heater connections a reference to ground (like the schematic dammit).
(2) Used non-microphonic tubes.

These two rules make life alot easier.

gr,
thijs
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Old 25th July 2002, 03:46 AM   #8
Gabster is offline Gabster  Canada
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hey wasp, what about the transformers on the clone you built? Were they standard or did you acquire replacement parts from Marshall?
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Old 25th July 2002, 09:19 PM   #9
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Hi Gabster,
I tried transformers from various makers and "replacement".
I quote them becasue theyr'nt original from marzhall but clones from MagicParts.
The results were very good with both.
I upgraded the trafos on marzhall heads with one from MP and the sound became "more wide".
The result is obvious: the original trafos had a narrower bandwidth.
Even if you can read that the reduced bandwidth smooth the harness of sound I prefer to use wide band trafos and shape the tone in the preamp.
I found that to obtain a good design I have to follow some rules:
1) Define what's a good sound. For me, heavy metal fan, is a deep distortion, articulated and aggressive.
2) The mix of preamp and power stage is important: in the preamp I shape the tone, the output must be more linear and fast (dinamic) as possible: ultralinear topology.
3) In the preamp I cut away the bass part of sound, distort, and then emphasize the bass. In pratice this "little trick" gives me a distortion very Zoldano but with the plus that the UL output stage preserve the detail of sound even if very overdriven.
Now I'll go on holyday till the 5th of August, cu all later.
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Old 10th August 2002, 03:51 PM   #10
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Default Back to reality

Hi Gabster,
I'm back.
In these days I'm designing a 3 channnel guitar preamplifier, only tubes inside.
The 3 channels are :clean,crunch and distortion.
The 2 tone stacks, a classic 1 res, 3 caps, 3 pots is after the gain stages.
In each channel there is a boost.
In the clean channel there are: deep,mid and bright switch.
In the rush and distortion only mid and bright.
In the rectification of the anodic current I use diodes, paralled with caps.
Other infos available on request.
I know that You are interested in a Meza Boogee clone but my time is very limited and I could only help with the project of the 3ch preamp.
If You want we could start a "open project".
Hope to hear soon.
Wasp
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