ECC99 Micro Amp Build Pics

[Zero4]

This was a fun little project I built last week. I was looking at various tiny amps online and thought the ECC99 used as a push-pull power section would be an interesting build.

[IMG:960:720]http://i477.photobucket.com/albums/rr13 ... niAmpa.jpg[/img]
Laying it all out - didn't bother looking at the dimensions of the power trans before ordering it. Oops! It's pretty big. It was cheap enough, so I just ran with it. Weighs more than the rest of the build.


[IMG:960:720]http://i477.photobucket.com/albums/rr13 ... niAmpb.jpg[/img]
Drilling the chassis and mounting hardware


[IMG:960:720]http://i477.photobucket.com/albums/rr13 ... niAmpc.jpg[/img]
Here it is all wired up (sorry I didn't get any pics in between. This literally only took a couple of hours to complete and I forgot to stop and take pics)


[IMG:960:720]http://i477.photobucket.com/albums/rr13 ... niAmpd.jpg[/img]
All buttoned up - from the back side


[IMG:960:720]http://i477.photobucket.com/albums/rr13 ... niAmpe.jpg[/img]
Selectable Impedance 4/8/16ohm on the dial - Makes it very versatile for testing purposes. This amp sits on a work bench, so I put the connections all in the back. (shielded input above the output)


[IMG:960:720]http://i477.photobucket.com/albums/rr13 ... niAmpf.jpg[/img]
From the front. 12ax7 on left, ECC99 on right. Posed next to a boss pedal for scale.


This was a very simple build based mostly on a couple different ECC99 schematics I tracked down online. Highly recommend for a beginner, or someone who wants a low-stress build.

Shockingly loud! Played through a 2x12 with 70watt speakers - it totally rocks. Clean up til 3 on the volume, then it crunches up. Past 6 or so, it starts to really saturate. It's funny, there's not a lot of variation in volume between 3 and 10. From 0-3, its clean and there is a volume roll off. Once you reach max volume at 3, it just distorts and maintains the same volume to max (at least as I detect it with my ears)

If I do another one, I would like to track down a smaller PT. That thing is huge. It made the amp a little awkward once I put feet on it, too. It wants to lean back on the back feet. You have to put a thumb over the chassis when you flip the power switch on.

[Structo]

Cool project.

Micro amp!

[Phil_S]

Find some weights and attach them with adhesive to counter balance the PT. I'm thinking about the kind of metal ingots you find at the bottom of some kinds of window treatments or what you find inside of telephone bases, and whatnot. I had a build that was lopsided. I put it into a cab and attached the weights to the cab. This will reduce your tip factor.

Nice build. I like it. Can you tell us about the topology or post a schematic? Self split, parallel SE, what?

[Zero4]

I am a newbie, and your questions go over my head.

The power section is based mostly on this schematic:

http://www.bilder-hochladen.net/files/b3cc-4-jpg.html

I would love for you to explain what it's doing. This is my 4th build, and I'm just trying to learn all I can and experiment with everything.

[Zero4]

Cool project.

Micro amp!

Thanks! Corrected the title.

[Phil_S]

http://www.bilder-hochladen.net/files/b3cc-4-jpg.html

I can't figure out how to access this.

[martin manning]

It opens right up for me, but I don't speak much German...

[Zero4]

Are you guys not seeing the schematic when you click on it? Works on both of my computers.

OK, added here:

[surfsup]

I see it fine on the orig link. That is a self split. Idea is to save a triode or tube by eliminating the PI and using a smaller PP tranny as well. Cheaper, smaller, etc. But not as efficient and I think only run in classA? IIRC

[surfsup]

the rectifier is wrong BTW.

Also what is your voltage at the B+? Just curious how much that tranny is loaded down.

I should also say NICE !!!

[Zero4]

I didn't pay attention to that rectifier because I have a center tapped PT. I used the rectifier design from the Mod 102 kit. (loosely, again)

A+ is 185V
B+ is 180V

My design is not exactly that schematic, but similar. I eliminated the presence control and I'm just running a resistor/cap there. I've also changed numerous resistor/cap values throughout. This is a decent guideline for building one, though.