"Micro-S" Terminal Cup Stereo Amplifier

[tomzarbo]

Re: "Micro-S" Terminal Cup Stereo Amplifier

That's just too cool Tom!

Thanks Chris!

Any thoughts on the fuse situation? The more I think about it, the more I think it's probably a good idea.

I just don't know what value to put in there, or what could go wrong to really need it. I imagine that if one of the solder joints came off and a wire touched something else on the board, that could be a problem; possibly cause sparking or something.

Heat from the amp section I'm not worried about, the chip/amp appears to be made out of some magic substance that amplifies sound without generating heat!

This fuse is 3 amps: http://www.parts-express.com/littelf...5-pcs--071-660
I think a fast-blow fuse is in order, but I don't know what the amps should be, maybe 5 amps would be more in order?

Not putting you on the spot Chris, anyone who knows more than me about this could chime in, which would be just about anyone!

TomZ

[Chris Roemer]

Re: "Micro-S" Terminal Cup Stereo Amplifier

That's just too cool Tom!

[tomzarbo]

Re: "Micro-S" Terminal Cup Stereo Amplifier

I worked up another of these small terminal cup amps using the same amp board.



It's basically the same but I removed the on/off switch from the terminal and moved the input and power-in connections to the edges of the cup.
The switch has leads that would be soldered to the leads coming from the amp board. The switch just cuts the (+) positive current flow, and has a copper looking terminal for connecting the (-) negative line to so the LED in the switch will light.



Since I don't have a set of speakers to try this out in yet, I've soldered lines to the switch and amp to make switching things around easy until this finds a permanent home.
I bought parts for a set of Jeff Bagby's Quarks to try this amp out in. It would be a perfect candidate I think. Both are pretty tiny and I think the watt output of this amp matches most small speakers well.

More pics:



The Potentiometer is connected to a small piece of flexible clear plastic tubing (1/4" inner diameter)... A few wraps of electrical tape made a snug enough fit on the pot shaft. Then a piece of 1/4" dowel became the extended pot shaft capped off by a spare knob I had from previous electrical madness. A slice of wooden dowel with a 1/4" hole drilled in it would work fine too. That's what I was going to do until I found these spare knobs.



Again, a zip-tie was looped, clipped, and super-glued to the back of the terminal cup to provide a stronger connection point/strain relief for the two wires that will connect to the crossover feeding the speakers inside the cabinet.

So basically, the parts list would be the same except for deleting the toggle switch and replacing it with a lighted rocker switch like this one: http://www.parts-express.com/parts-e...d-12v--060-770

It has a 12V ready LED in it. Just drill a hole in the front of your speaker cabinet, solder the leads on, goop it in with caulking, speaker caulk, etc.

********

Here's the same potentiometer/rubber tube/wooden dowel/knob treatment applied to the first amp...


It should make adjusting the volume easy, just feel for the wires exiting the cabinet and the volume knob will be between the wires. The rubber tube part could be made longer for more finger clearance... it would droop a bit, but that's no problem.... or you could just leave a length of 1/4" dowel back there to act as the knob. That would work fine too.

When I get the quarks put together, I'll post some pics of that setup.

The only thing I can think of to add would possibly be a fuse somewhere in the mix. A built-in holder like this one: http://www.parts-express.com/littelf...older--071-510 would work I think. If you moved the super-glue'd wire tie-down point further down to where it goes on an angle there would be room for the fuse holder on the panel next to the amp board.

I'm not sure what amp fuse to put in it, or if it's really even needed. Maybe others more experienced could chime in here... The board doesn't have a fuse on it that I can see. If I were to give this to a friend, I think I may want to add a fuse just to be safe since there will be electronics inside a sealed wooden box and things do sometimes go wrong.

Anyway, this has been fun to mess around with and I can't wait to get them installed in some speakers to see how they do built-in. I have a few small speakers that this amp would work well with, some with this exact terminal cup, but they all have my usual crossover-on-a-stick treatment...



So I guess I need to make a new set...
More to come...

TomZ

[tomzarbo]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Very nice job! But what does the switch do? On/off? or something else?

Yes, it just turns on/off the power to the amp. It cuts the positive lead.
I have another amp/terminal cup to do another one of these on... I plan on removing the switch from the terminal cup and switching (get it?) to an LED lighted rocker switch that can be mounted to the front of a speaker. You will be able to see if it's on that way and turn it on/off without feeling around the back.

TomZ

[carlspeak]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Very nice job! But what does the switch do? On/off? or something else?

[Navy Guy]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Really cool project Tom!

[Kevin K.]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Contractually, I'm restricted to one DIY event per year for the 2015 DIY season. I'm hoping that my pending free-agency will enable me to attend more events in the future.

You never fail to make me laugh out loud when I read your stuff!:D I hope she understands what "free-agency" means.;) Nice job on this little project, really cool.

[djg]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Nice project, tight little thing. All my questions were answered by reading your writeup.

[lowpolyjoe]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Great project and writeup Tom

[howard]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Good job, Tom!

[Paul K.]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Really quite neato!
Paul

[tomzarbo]

Re: "Micro-S" Terminal Cup Stereo Amplifier

What about the sub out?
Otherwise- looks pretty cool,
Wolf

I'm still waiting for that amplifier to get here. This one: http://www.parts-express.com/21-hi-f...8-vdc--320-608

I am really looking forward to getting those amps in. Kevin K sent me some really nice plastic panels pre-machined to mess with. I've got some ABS sheets from PE and even a 4" square anodized alum. plate to try out on that project as well.

I'm playing around with these in the meantime. Sharpening my soldering skills you know. Actually, just handling these tiny wires is kind of a pain with my bloated Shrek-type fingers. The thin wire used to wire this stuff up has more 'jacket' than wire and doesn't remember the shape you bend it into very well. I was soldering with one hand and holding the wire in a tiny pliers with the other. Soak up a small blob of solder and 'Pffffftttssszzzzz' get out before the thing melts. Maybe I had my temp to high on the iron, I'll have to double check that now that I think about it. Crossovers are much easier.

That's sweet! Gonna bring it to InDIYana?

Contractually, I'm restricted to one DIY event per year for the 2015 DIY season. I'm hoping that my pending free-agency will enable me to attend more events in the future.

Truthfully, my spouse is fine with me attending MWAF and I may be allowed to escape for Roman's Brooklyn event next year since it's so close, but that's about all I can get away with at this point, I gotta keep the wifey happy, you know! I do build a lot of projects over the course of a year, but most of them are 'Zarboified' versions of others projects, borrowing from the excellent designs of so many others...

For about $25 you can have a decent hidden amp including terminal cups for both speakers. Not too shabby price-wise. Oh, plus the price of a 12V power supply if you don't already have one laying around.

Thinking about it some more, I may wire in leads for a LED that could be mounted on the front of the powered speaker, just for some bling as well as a reminder that the thing is actually on.

Thanks for the kind words...
TomZ

[Pallas]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Very cool

[LongHorn64]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Tom you knucklehead! That's an absolute stroke of genius. I'm really impressed. WOW. All the best, Mike

[kenny_k]

Re: "Micro-S" Terminal Cup Stereo Amplifier

Very inventive and darn nice.