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Reverse engineering an amp?


Gruupi

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I would think that any decent electronics buff should basicly be able to make a really good copy of any amp. You could even go so far to measure the capacitance or resistance of each piece in a that special amp and get the sound spot on. Say Robben Ford wanted a duplicate of his favorite Dumble, couldn't someone with out to much effort copy that? I am not saying you could market and mass produce such a thing legally, but for the person that wanted something really specific, what stops a boutique builder from making an exact copy? Am I missing what variables make an amp special, I'm not an electronics guy, just asking the question.
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Originally posted by Gruupi:

Say Robben Ford wanted a duplicate of his favorite Dumble, couldn't someone with out to much effort copy that?

K & M (Two-rock) do it the best, but as far as dumble emulation is concerned, Howard covered all of his circuits with huge amounts of goop and epoxy so that no one could do what you are talking about

 

So, most of it is highly educated guess work

 

Now as far as old Marshall Circuits go, it is tough because that was with all English Military Spec components, which are hard to come by these days

 

Mojomusical supply has all of the kits for just about any classic amp you would want.

 

Seems like Mercury Magnetics is making some high quality stuff

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Originally posted by yZeCounsel:

Mojomusical supply has all of the kits for just about any classic amp you would want.

Yeah, but for the prices they charge for kits, you could get a real vintage amp already put together.

Always remember that you�re unique. Just like everyone else.

 

 

 

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Originally posted by Picker:

Originally posted by yZeCounsel:

Mojomusical supply has all of the kits for just about any classic amp you would want.

Yeah, but for the prices they charge for kits, you could get a real vintage amp already put together.
Not true.

If you want a pre 1972 JTM 45 you are going to pay at least more than 2000

 

Good God, an 80W Tweed Twin would be 5 bills easy

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I was even being more specific, we all know that to amps of the same model can sound different. I was thinking that you could put a meter to each componant and match its characteristics. I know you wouldn't want to do this to every amp, but if you were a rock star and came across a holy grail amp, I would think you would want to duplicate it.
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It can be done, it is being done. Take a look at all the Marshall non-master clones and Marshall 18W combo clones there are everywhere. I've seen slews of cloned Fender amps too. Ebay is rife with cloned guitar equipment.

 

All the parts are available, if not exact parts, similarly spec'd replacements, etc.

 

It simply boils down to being a lot of work and oftentimes counterprofitable. While you might enjoy doing it and will learn a lot, you won't usually save any money unless you're copying something vintage or rare. Amplifiers are a little better in this regard, but stuff like stompboxes are pretty much impossible to make any money on because manufacturers can sell very professional looking stuff for less money than you can buy the parts for.

 

People build clones of certain amps for themselves a lot, but if you want to start selling them that's a whole different sack of monkeys.

 

Also, poking around in tube-fired equipment should only be done by someone who knows what they're doing, as you can get killed pretty dead by some of the voltages you'll find in there.

 

So your basic answer is yes.

Dr. Seuss: The Original White Rapper

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WWND?

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I've done it.

 

I cloned my '57 Fender Super-Amp. Went through with a meter and measured all the component values (some of which are now drastically differerent from the schematic).

 

Mercury Magnetics makes exact reproductions of all the old Triad transformers that Fender used. The interleaving is the same. I used those.

 

Made a lot of layout and component changes because I'm building a better amp than the original. But I could have made an exact replica if I wanted to. I'm 3/4 done now (after an 8 month Katrina interruption). I'll let everyone know how it turns out.

 

FYI Dumble amps aren't probably that hard to clone because while the circuits are covered in goop, they're still just modified Fender circuits.

 

Also, none of this is illegal. For all intents and purposes, tube circuits are open source. There are few patents - Mesa Boogie has one for the channel switching MKII.

 

Back in the day, Fender used circuits that Western Electric gave away for free. Gibson offered it's own version of almost every Fender tweed amp. The first Marshall JTM 45 was a copy of a Fender 5F6 Bassman. The first Mesa/Boogie was a hopped-up Fender Princeton. The preamp circuitry in both the Mesa Rectifier series amps and the Peavey 5150 are lifted from the Soldano SLO 100.

 

No one gets to claim prior use.

"You never can vouch for your own consciousness." - Norman Mailer
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  • 3 months later...

Just noticed this thread and felt I should respond. In answer to the original question, yes there have been several Dumbles that have been degooped. I have over 100 pictures of such.

I build custom tube amps for a living and a customer of mine came to me wanting a 'Dumble Clone'. I spent a while doing the research and ended up building a replica of a later model 100W Overdrive Special (HRM Model with Skyliner tone stack). Here are some pictures of the finished amp and one showing part of a degooped original circuit. Incidentally these amps do really sound stunning and are virtually silent. I have sold several since and use one myself when I play live.

 

http://www.carolannamps.com/dumble_clone.htm

 

Kind Regards, Alan.

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Originally posted by yZeCounsel:

Not true.

If you want a pre 1972 JTM 45 you are going to pay at least more than 2000

When I got my '65 with matching 4X12 in the early 80s, I got it for $250....MINT. :thu:

 

They ain't that cheap now. ;)

 

I told Jim Marshall at NAMM I had one, and his eyes lit up BIG and said to never sell it...it's the best amp he made.

A Jazz/Chord Melody Master-my former instructor www.robertconti.com

 

(FKA GuitarPlayerSoCal)

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  • 4 weeks later...

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