And to all:

Be careful with mains voltage!!

To get full power you'll need either 36 to 50vct or a 18 to 25v dual secondary transformer with a VA rating of around 160. I little less or a lot more VA won't hurt. Just remember that any poweramp is only as good as it's power supply.

RDV

Quote from: joecool85 on June 15, 2006, 10:47:03 AM
I'm using mine as a PA and driving a dean markley 1x10.  I can't vouch for a 2x12 or 4x10.  I think RDV is using his on a 2x12 though.

I was driving my 412 @ 16 ohms last time I had it plugged in.

Lately I'm working on my DIY stereo speakers more than anything. AADD you know.

RDV

Quote from: teemuk on June 15, 2006, 11:39:37 AM
I wouldn't trust only on heatsinking a high power amplifier in gig situations. The ambient temperature on stage is huge. It's safe to assume the power dissipation might start from heatsink temp of 40 degrees of celcius not nominal 25.

If I ever use a DIY chipamp for gig purposes it will be fan-cooled. I doubt it ever happens though. There's too many inexpensive commercial amps out there. I just use them as stereo equipment and practice amps.

RDV

Quote from: joecool85 on June 15, 2006, 09:04:10 AM
I didn't bother on mine since it is so huge, plus I wanted a simple solution. And there is nothing more simple for a heatsink than just grabbing the biggest one you can afford and bolting a chip to it lol.

The only way you'll overheat that one is to actually outdo the heat transfer rate. It's possible with a 4 ohm load but unlikely with an 8 ohm load. The Spike protection would finally kick it at that kind of level.

RDV

Quote from: lliw on June 15, 2006, 11:17:49 AM
Sounds good but i dont have a wha pedal.

Is their any particluar box that i could make to get the sound?

like a cirtan type of overdrive?

You'll need a wah for MFN. Nothing else does it. Sorry.

You can just build a wah circuit, put it in a regular box, then just use a regular pot to set the wah to the right freq. It's been done before by folks who like that "cocked wah" sound for leads, or MFN of course.

HTH

RDV

With proper design, filtering, and load, these amps run fairly cool though really. A huge heatsink is really not neccessary but doesn't really hurt either. If you run two chips bridged or parallel, there almost isn't a big enough heatsink period, and fan cooling is almost a neccessity. This is more true as a guitar amp than in music reproduction however due to the dynamic range of the guitar.

RDV

Quote from: DreamSeller on June 15, 2006, 04:13:32 AM
Does anyone do this. I was at work last night and new cash registers came in, They were packed in the wavy foam stuff that looks just like the sound proof foam, I figured I might as well give it a go since it wont cost me anything.
Does anyone here use the stuff on the inside of their cabs etc.

Definitely keep that stuff, it has all kinds of uses. Audio & otherwise. I just ran out of it myself cause I've been making DIY stereo speakers and subs. I'm on the lookout for more.

What it does for speakers is what Elmo described plus it makes the woofer think that it's in a much larger cabinet which is very handy when designing small bookshelf size speakers.

RDV

Quote from: skey on June 14, 2006, 11:36:54 PM
Neither of the above heatsinks above seem to take advantage of thermal airflow.
Sometimes smaller is better if it's less bulky. Is there any convenient way to figure out a useful minimal size you'd need?

The one in the 1st picture does not take advantage of thermal airflow(though it's big enough to not need it), but the 2nd one is outside the cabinet. How much airflow do you need? It's in free air.

Please don't say that a smaller heatsink is better because it's not. The smallest heatsink you can get away with is best for space saving purposes, but there is no heatsink that is "too big".

There is no convienient way to calculate heatsink size other than doing the math from the datasheet.

Regards

RDV

I know a bunch of blues players who swear by those old Peavey solid state amps but they do say they want the ones with a 12" in them. One to check out if you see one is the old Studio Pro 40. It rocks.

RDV

A newer or older model?

I used to like those back in the 80's, though the speaker did limit the reponse.

Have you tried plugging it into a bigger speaker?

RDV

Hey Pete, if you get a PCB from Joe, we'll fix you up with a parts list and stuff.

RDV

You can put it in yer guitar.

RDV

  Like diode clipping, maybe warmer cause of the Geranium. 

RDV

I know what to do with them! I've got a box of 10,000µF caps looking for a home.

RDV