ClassDaudio amp project

PWRRYD

I decided to start this new thread to share pictures and details of my new amp project.  Unlike most of my projects this one will NOT be housed in a hardwood, 4 sided case, with an aluminum top and bottom.  Our IT Manager at work called me a few weeks ago and asked if I wanted an old UPS unit that he was upgrading.  Hating to see anything with potentially useful parts go to the scrap heap I said "Yes!"  Nothing inside except the muffin fan was worth keeping... but the case!  A perfect case for an audio project!!!!  Of course it'll need some modification, specifically a new rear panel.  I'll snap some pictures of it.  

The model of amp board I purchased was the CDA-250:

http://www.classdaudio.com/cda-amplifier-modules/cda-250-power-amplifier-module/

I already have a 400VA 35-0-35 VAC toroid transformer and a small power supply board (rectifier and cap banks).

dcibel

If I'm not mistaken, all the ClassDaudio boards are based on IRS2092. It can produce great sound, my HT amp is built from five L15D-Pro modules that you can find very cheap on eBay, especially if you don't mind soldering them yourself. The L15D is basically a copy of the IRS2092 eval board from International Rectifier, I'd imagine the CDA-250 is not much different. You won't be disappointed.

Kornbread

   Why this vs the B&O Ice, cheap t-amps, or some of Hypex's offerings?

jr@mac

DIY for the sake of DIY

PWRRYD

That's a good question KB.  I've already built a ClassDaudio amp using two bridged SDS amp boards.  That amp can do 500W x 2 into 8 ohms and much more into 4 ohms.  The ClassDaudio boards sound awesome to me.  This CDA-250 board is the same one Pete Schumacher used (although he used 2 bridged) in his PCeceiver project he demo'd in Iowa a number of years ago.  I have never heard the Ice or Hypex boards, I have read that they are great too.  But every other "cheap" amp module I've heard, like the Sure Electronics and Yuan-Jing stuff, has not sounded very good to me at all.  Some of it sounded flat out bad.

PWRRYD

Here are some pictures of the case.

PWRRYD

Here is one possible layout.  I will play around a bit to find the best layout:

jhollander

What's the difference between the CDA and the SDS boards?

PWRRYD

It is my understanding that they share the same core circuit topology and IRS devices. The SDS boards have:  balanced inputs, larger finned heat sinks, and molex connectors which allow off board gain controls.

Since I run a single ended signal chain, I am going to sister a larger finned heat sink to the existing one, and I don't need external gain pots, the CDA seemed appropriate.

There maybe other differences I am not aware of besides the $100. Lol
.

Kornbread

PWRRYD said:

That's a good question KB.  I've already built a ClassDaudio amp using two bridged SDS amp boards.  That amp can do 500W x 2 into 8 ohms and much more into 4 ohms.  The ClassDaudio boards sound awesome to me.  This CDA-250 board is the same one Pete Schumacher used (although he used 2 bridged) in his PCeceiver project he demo'd in Iowa a number of years ago.  I have never heard the Ice or Hypex boards, I have read that they are great too.  But every other "cheap" amp module I've heard, like the Sure Electronics and Yuan-Jing stuff, has not sounded very good to me at all.  Some of it sounded flat out bad.

    Thanks, that's the answer I was looking for. 

   I've read the irs2092 can sound lean on the bottom and a little bare otherwise.  Also heard that of the Hypex ucd and n-core offerings but with a full bottom end.  I don't know if there's as much a difference as some make or if it's a fly shit in pepper thing.  They all spec fantastic, the n-core exceptional.

   I'm in the market for an affordable drive anything amp that sounds good, (full but controlled bottom and smooth but not subdued mid/treble, I hate glaring treble) where I can close my eyes and reach out and touch the performers.   

   What have you tried, or heard, and your take on them, good or bad.

   Is it possible to mate something like the irs2092/ICE/Hypex with something like the tube pre your working on, and have the best of both worlds?       

Wolf

I love my Crown XLS Drivecores, for another recommendation.

kennyk

How low an impedance can this handle, bridged and non-bridged?

Wolf

If that was directed towards me- Bridged at 4 ohms, and stereo at 2 ohms.

D1PP1N

Do the drivecores have dsp built in like the inukes? Im going to have to pick up something else i was using a small amp and my minidsp but stopped using it. Prefer an all in one solution. 

Wolf

The XTi series does have DSP. The XLS have HP/LP filters, and that's about it. Be forewarned though- I hear the fans on the XTi are a lot louder than on the XLS.

PWRRYD

Wolf please start your own thread about your commercially purchased pro amp.  This thread is about my DIY project.

Wolf

Of course it is- no hijack intended.

D1PP1N

Sorry to sidetrack your thread Craig. 

PWRRYD

Guess I'll hijack my own thread a little...  I'll be getting back on this class D project soon.  I've just been busy finishing up that tube pre-amp project, helping my son build a Pine Wood Derby car, and building some snow people.

rjj45

 I built a 2092 amp with some L15 boards and that buyout PS.  Sounds pretty great to me, and lots better than any of the dinky 3116 or 2022 amps. 

dynamo

Your case has a nice added benefit of a built in divider for some ps shielding.

I see you said you will add another heat sink, do you plan to expose that on the case or keep it inside?

PWRRYD

I'll keep it inside.  I plan on running a temp controlled case fan and I can adjust the speed of the fan to keep noise at bay.

isaeagle4031

I really like this Craig. I'd like to build something similar to use on the RetroActive project. I've got an inuke1000dsp and am considering buying another or 3000dsp, but this would be a much more elegant solution.

jhollander

Coax in the dungeon? Is that InDIYana entry?

dynamo

PWRRYD said:

I'll keep it inside.  I plan on running a temp controlled case fan and I can adjust the speed of the fan to keep noise at bay.

That’s cool (pun perhaps intended). Could you do an automatically adjusted fan speed, self varying with increased heat sink temp? Perhaps “on” to a minimum speed at a certain temp and then increasing only if temp keeps going up?

isaeagle4031

jhollander said:

Coax in the dungeon? Is that InDIYana entry?

No much to big and these are really designed for bi-amp. The 4012ulf-8s are not great above 150.

PWRRYD

I ran a little test tonight, transformer sitting on the floor, cheap ass RCA interconnects, etc.  It fired right up, zero audible noise, super powerful, and sounded great to me.  More to come.

MartyH

Last I saw your son Craig, he was in a stroller.  Man, time flies.  Good looking kids!

PWRRYD

Thanks Marty!  Not bragging but my son's car took first place in his den races and third overall in his pack.  Sounds geeky but the whole pine wood derby night was really fun for all of us.

MikeJennens

Thanks for this thread Craig, I'll be following as I'll probably be buying one of these amps before too long. Now.... about a case..................

PWRRYD

Hi Mike,
I worked on it a little today.  I've completely switched up the layout.  Now the amp board is mounted in the front right compartment (where the transformer was in the first pictures).  I've cut an opening for a fan on that partition wall.  Pics to follow.