REAMP BOX (original) - Fixed with schematic

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Whoops

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Hi,
I fixed today an original John Cuniberti REAMP box.

here is the schematic:

REAMP SCHEMATIC.jpg


The transformer secondary was open, but somehow applying heat to the Pins solved the issue, probably re-soldered the coil wire to pin inside the potted transformer.
They used an Altran C-2878 transformer, I can't seem to find information about that transformer anywhere.
I measured the DC resistance of both Primary and Secondary. The primary measures 56r and the secondary 1,5k.

here are some inside photos:

IMG_3505.png

IMG_3507.jpg

IMG_3509.jpg

This REAMP is no longer being sold by John Cuniberti company, he sold the "REAMP" name and patent to Radial.
"Oakland, CA – January 1, 2011 – Recording engineer John Cuniberti announced today that he has signed an agreement to sell his Reamp patent, trademark and all business assets to Radial Engineering Ltd"

You can check and download the patent docs here:
 
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Whoops

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One thing that puzzles me about this design is that the transformer is not wired as a step down as I would expect but actually as a step up,
am I seeing this right?

It seems there's an H pad attenuating the input signal, then the transformer provides de-balancing, isolation and increases the signal, then the output pot attenuates the signal again.
It seems a bit awkward that a transformer wired as step up was used, other reamp circuits like "NewYorkDave" reamp use a stepdown transformer, any reason for this?

thank you
 

NOON

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No strong technical theories, but I've seen some DIY reamp boxes that put a guitar pickup in series with the output circuit to introduce the inductance etc normally seen from a guitar pickup to supposedly recreate the complexities of the resonant RLC relationship between amp and guitar. The secondary of this transfomer appears to be in the region of a typical guitar pickup impedance.
 

carboncomp

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You can check and download the patent docs here:

Interesting that RADIAL purchased it just 5 years before it expired.
 

Whoops

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Interesting that RADIAL purchased it just 5 years before it expired.

Well, that’s still 5 years to make profit, but above all they bought the “REAMP” name, and that registered name never expires

No other company can call their reamp box type product a “Reamp” only Radial can
 

carboncomp

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Well, that’s still 5 years to make profit, but above all they bought the “REAMP” name, and that registered name never expires

No other company can call their reamp box type product a “Reamp” only Radial can
Yes, you're right the trademark has got to be what they were really after.

Though I did just check and there is no registered trademark for REAMP here in the UK, wonder if someone forgot to tick a box or if they just considered us a too small of a market to bother?
 

Whoops

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I have no idea how that works internationally, but there's no other brand using the name "Reamp" written exactly this way in their product besides Radial, although there's a lot of companies selling reamping type devices in the market
 

carboncomp

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Guess it could be a quirk of British law that you don't HAVE to register a trademark to own it and defend it. But sure makes the process of enforcing much easier if you do!
 

baldrich

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Hi,
I fixed today an original John Cuniberti REAMP box.

here is the schematic:

View attachment 84270


The transformer secondary was open, but somehow applying heat to the Pins solved the issue, probably re-soldered the coil wire to pin inside the potted transformer.
They used an Altran C-2878 transformer, I can't seem to find information about that transformer anywhere.
I measured the DC resistance of both Primary and Secondary. The primary measures 56r and the secondary 1,5k.

here are some inside photos:

View attachment 84271

View attachment 84272

View attachment 84273

This REAMP is no longer being sold by John Cuniberti company, he sold the "REAMP" name and patent to Radial.
"Oakland, CA – January 1, 2011 – Recording engineer John Cuniberti announced today that he has signed an agreement to sell his Reamp patent, trademark and all business assets to Radial Engineering Ltd"

You can check and download the patent docs here:
Did you ever locate a comparable transformer?
 

L´Andratté

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The transformer ratio issue interests me too, Whoops dc-resistance readings hint at a not so small step up ratio,
why? The input of the REAMP is supposedly connected to the output of a line level amp or am I in the wrong movie here🙃
 

Whoops

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The transformer ratio issue interests me too, Whoops dc-resistance readings hint at a not so small step up ratio,
why? The input of the REAMP is supposedly connected to the output of a line level amp or am I in the wrong movie here🙃

That also puzzles me.
There's an H Pad at the input to attenuate the +4dBu Balanced Line signal,
and then there's a step up transformer, I really don't see why.
Attenuating then stepping up seems really strange, I would guess a step down transformer would be used.

I've built quite a few DIY reamp boxes and all of them use a step down transformer.

Maybe someone can explain why a step up transformer was used here as I'm really not seeing it.
maybe to increase the output impedance... ??? I don't know

this is from the patent:
"Also, transformer 70 is a 500 ohm/30 kilohm audio transformer, such as a UTC 0-10 audio transformer."
 

analogguru

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I'm still kinda shocked that you can patent simple circuits like this in the us system..
Getting a paper is one thing (it is stamped by a subaltern officer), defending it in the real world (in front of a judge and experts) is another.

I would sleep very well if I would be sued for violation of a "patent" like this. This could become very expensive for the plaintiff - beside the not so small costs to obtain this wortless paper.
 

gurkan75

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I’ve tried a couple of the different reamp concepts. It sounds a bit more convincing to me with a high impedance winding facing the amp. One guess is that the original utc transformer sounded good hooked up like that, and the two attenuators are there to compensate for mic pre gain in the recording + transformer gain. The values of the 1st pad seem to suggest a slight impedance matching too.

Out of the ones I built I’ve kept the one that was a stepdown transformer into a pot, into a high impedance 1:1 transformer. I had the parts lying around already, otherwise it would probably have been too expensive.
 

emrr

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Looks like roughly a 17-20dB input pad to a 600:30-50K transformer to a 50K fader. Prob unity gain with loss option concept.

I haven't tried one like this, the only thing I've built is lo-Z into resistive series build-out.
 

Bo Deadly

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I’ve tried a couple of the different reamp concepts. It sounds a bit more convincing to me with a high impedance winding facing the amp.
If you want to reproduce the signal at the amp input exactly, then it is not correct to match the source impedance characteristics to those of a guitar.

The correct way to reamp, IMO, is to capture dry signal at the amp input with a very high impedance buffer (10M) so that you're simply tapping into what the amp input "sees" without adding any load or parasitics (capacitance). On playback, use a transparent buffer to inject the dry in place of the guitar taking care to make sure the level is the same. This way, you are simply reproducing the signal exactly as if the guitar were the source.

An ideal reamp box might have a switch that switches between either the guitar and the high Z buffer out OR the playback source input (leaving the guitar disconnected). This would mean having both send and receive cables connected to the converters. Or just one cable could be used for both send and receive (in this case one should be careful not to connect the send amp to the converter output but with proper protection it shouldn't hurt anything).
 

gurkan75

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Agreed, this was pretty close to the method I used. (Record amp + d.i., reamp and compare w exact settings and mic placement. Try different d.i.s also). In the end there are just so many variables involved, especially if the recording side is unknown (I do mostly mixing). Just choose something that sounds as good or subjectively better than the reference amp recording. To make a box that will exactly reproduce any d.i. guitar into any amp seems futile to me. Maybe I was restricted by the parts I wanted to use up.

One overlooked thing is the range of levels needed. A direct recording of a soft strummed guitar will often need a LOT more attenuation than a punk rock bass guitar played with a pick. A bit counterintuitive perhaps, but peak to rms levels, interface calibrations and recording preferences can be all over the place. I preferred to switch the primary & secondary of the stepdown tx for ”range” an then just trim with the pot.
 
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