Fender '57 Mini Twin

Tube or solid-state, this section goes to eleven!

Fender '57 Mini Twin

Postby JiM » 06 Dec 2009, 22:51

I don't know where to post that, as we don't have a "pimp my toy amp" section ...
Dear moderators, feel free to move to "amplifiers" if it's more appropriate.

So, i've received this cute tiny amp yesterday ... and i couldn't resist, i've opened it today. :slap:
Some gutshots (from someone else) : http://www.bustedgear.com/repair_Fender ... ion_2.html

There is a single 4558 opamp as preamp (only one half used ! :shock: ), and a 0.5W chipamp, more or less similar to a LM386, as power amp. It's a twin, so there's two 2" louspeakers, in series.
The tone control is interesting, and very similar to the "contour" that i like so much in my old Valvestate : it goes from mid-cut/hi-boost to hi-cut, with mostly flat and slight hi-boost in between.

The clean sound is great for the size, and suprinsingly loud, but the distortion is quite harsh : it's indeed due to a pair of diodes to ground ! The classic tricks should apply : using LEDs as clipping diodes, maybe moving them to the feedback loop of the gain stage, using the second half of the opamp as a buffer before the tone control, etc.

Maybe i'll try to add a tube to it someday ... :mrgreen:
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Re: Fender '57 Mini Twin

Postby lolbou » 06 Dec 2009, 23:16

Cool, thanks for the schem. :D

I would add an external speaker plug to play on a big cab. I did it on my mini Orange Crush, and it's nice...

Oh, and it does seems appropriate to me in the Amplifiers section. Let's move on...
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- Uh, no, I'm a mocker.
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Re: Fender '57 Mini Twin

Postby ansil » 06 Dec 2009, 23:18

the "chip amp" is the same as the one in the marshall ms-2 posted all over here and the net as well. it works quite well for driving a larger speaker. instead of diodes to ground what about using the second opamp to od that and then a blend knob to blend in the two. take a small camera flash transformer and drive the piss out of it with a single opamp and dump the output into the front end as a recovery stage and check that out. add some feedback to it. you could definately make it into a little tube head.

ed
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Re: Fender '57 Mini Twin

Postby Kilby » 07 Dec 2009, 17:09

Would the transformer in those awful energy efficient (compact fluorescent) bulbs be suitable ?
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Re: Fender '57 Mini Twin

Postby ansil » 07 Dec 2009, 22:57

thats a good idea would probably be noisy though but i am speculating i have a dead one will have to check it out.

ed
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Re: Fender '57 Mini Twin

Postby lolbou » 07 Dec 2009, 23:28

ansil wrote:take a small camera flash transformer


Hey Ed, any specifications on these (windings, impedance, whatsoever)? Just curious for some other purposes...
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Re: Fender '57 Mini Twin

Postby Solidhex » 08 Dec 2009, 00:48

Ah cool

I have one of these. I like the tone knob too. Interesting to see what's inside.

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Re: Fender '57 Mini Twin

Postby HoggYBhoY » 09 Dec 2016, 19:23

any idea the spec of those 2 inch speakers?
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Re: Fender '57 Mini Twin

Postby ansil » 11 Apr 2017, 04:11

I know it's 7 years too late I never actually received a reply about this in my email sorry the Transformers all very depending on manufacture. however if you're looking to make like a Tycho brahe octave box it can be done
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