Micro Champ

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Moderator: Joe Malone

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Joe Malone
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Micro Champ

Post by Joe Malone »

Image

Hot off the bench. A champ guitar amp miniaturized from the original 6SJ7 and 6V6 to a EF86 and 6AQ5. Runs on external 12v SMPS and has internal DC to DC to make the 350v rail. Power on lamp is blue leds under the tubes. Sounds great :-)
Joe :-)
JLM Audio
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astrovic
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Joined: Sat Mar 03, 2007 12:14 pm
Location: Melbourne, Australia

Post by astrovic »

Nice!!!

Did you whip that up while waiting for all the new boards to arrive?

chrisp
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Location: Sydney, Australia

Post by chrisp »

But Joe, what happens when the drummer tries out the new stomp box?
Chris P
---------------------------------------------------------
I do lots of things. I believe eclectic skills are best.

astrovic
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Location: Melbourne, Australia

Post by astrovic »

LOL!! Took me a second, though... :D

poserp
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Location: Los Angeles, California

Post by poserp »

Kit, kit, we want a kit... I have an old transistor amp that I'd like to overhaul (i.e., replace most of the electronics, keep the spring reverb and tremolo), and this would be the perfect thing for it. So here's my vote for making this into a kit at some point in time.

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Moogus
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Post by Moogus »

We built this for a local engineer (who just registered for the forum, I see) after I lent him my Champ which is just the standard 6SJ7+6V6+5Y3 type using New Sensor transformers - all old school and big and hot.

He loved the sound of it and asked us to build another. But of course we had to mess around with the design...

Its almost exactly the Champ circuit but with very modern PSU technology, and the equivilant miniature tubes to the 6SJ7 and 6V6. Its not quite as loud as my Champ, which is a good thing as it will be living in a studio thats built into a shipping container. So great sound at low volume is the order of the day.

Hes been using it for a few weeks now and reported it was running very hot, due to the complete lack of ventilation of the box. So we milled the top and bottom of the case with a pattern of 3mm holes, which seems to have fixed the heat problem. And it looks even better now.
Well put up an updated pic soon.

Im all for a PCB for this amp as it would be very simple and allow you to build one easily in a day. The lack of mains power inside the case makes it comparatively safe to build aswell.

Hopefully well post some sounds soon too.


M@
Permission to buzz the tower DENIED!!

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Joe Malone
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Post by Joe Malone »

Used the CNC Milling machine to add some top and bottom panel venting to get some air convection going as it was getting very hot.

Front panel has input jack, gain control, High boost switch, Pentode/Triode Switch and Power switch.

Back panel has 12vdc connector and speaker output jack.

Image
Joe :-)
JLM Audio
Capturing Audio without Injury

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Godders
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Location: Bath, UK

Post by Godders »

I'd be all over a kit for one of these.

Cheers

Nick

just.sounds
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Micro Champ

Post by just.sounds »

This thing looks great! if it is going to be a kit i'm in for two!
:D

And this psu idea is also nice maybe you can make kits of that alone.
I think a lot of tube freaks would like such a psu for powering pre amps and make up gain amps. maybe even tube microphones. Keep up the good work!

toddd
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Location: brisbane

Post by toddd »

don't make us beg joe...

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Moogus
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Post by Moogus »

Give us some idea of what people would want to pay for a full kit for an amp like this (ie drilled case included). Or would you just want parts and make your own case?

M@
Permission to buzz the tower DENIED!!

just.sounds
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BOM

Post by just.sounds »

As a dutch guy I have to be a cheap bastard so i would say

As cheap as possible :)

But i would like a kit with housing but without all the parts that are in the signal path.

I think you can make them cheaper than at

http://www.tubeampdoctor.com

Bear
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Post by Bear »

What sort of chasis size are you using?

Bear

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Joe Malone
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Post by Joe Malone »

What sort of chasis size are you using?
Diecast box measuring 119mm (4.7") x 93mm (3.7") x 55mm (2.2")
Joe :-)
JLM Audio
Capturing Audio without Injury

Bear
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Post by Bear »

Wow, that is tiny. A Hammond 1590D box would be even roomier. I might collapse one of those trying a similar project put with a power transformer.

Bear

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