[ebag4]

The input coupling caps are the orange surface mount devices (3-4 mm on a side) by the input terminals.  They are physically tiny by comparison to the output caps (but have somewhere around 100 times the rated capacitance).  Replacing them on the board would be near impossible because of size diferences and lack of holes for physical attachment .

It appears that you could remove the orange SMD caps, solder a jumper across the pads and then series the new cap between the RCA input and the positive through hole connection of the removed terminal block.  I haven't tried it but it at least apprears to be doable.

[dewardh]

Check out Marchand Electronics... they are selling the 1000w ICEPower 1000ASP modules for $490 each (SMPS power supply is integral, but you need two modules for stereo) . . . A bit pricey for my tastes

A bit pricey for me, too, although probably very nice. It's also *far* more power than I ever need, since I use active crossovers . . .

I've been lurking on this thread contemplating the ClassDAudio kits for some time now.  I may have to give them a try, but want to make sure my Reference Line Preeminence Passive Pre will work with them first.

Might be best to wait for the higher input impedance boards that are rumored to be coming, unless you're absolutely sure how the Passive Pre responds to low impedance loads (and the pass-through effect on your sources).
 

[dewardh]

It appears that you could remove the orange SMD caps, solder a jumper across the pads and then series the new cap between the RCA input and the positive through hole connection of the removed terminal block.  I haven't tried it but it at least apprears to be doable.

Yes, that's probably the easiest option.  Might want to remove the 100k input "load" resistor too, and move it (and a RC low-pass) to the RCA connector.  Exactly how you'd do it depends on physical layout and shielding . . .

[wushuliu]

Yes, that's probably the easiest option.  Might want to remove the 100k input "load" resistor too, and move it (and a RC low-pass) to the RCA connector.  Exactly how you'd do it depends on physical layout and shielding . . .

Deward, are the input caps for the IR amps 22uf per the pdf?

[dewardh]

Deward, are the input caps for the IR amps 22uf per the pdf?

The IR reference design specs 22uf.  I do not have an IR reference board to examine.  The caps on the classDaudio boards that I have are marked, and measure, 10uf.

[indietronic]

hello audiocircle forum and everyone! just joined extremely tempted by what i've already [34 pages!!] read here..

so my question is .. which one would you be your pick to drive ATC SCM11 ? 250 watts x2 @8ohm ? other ? has anyone tested one of these with ATC gear?

[Mariusz]

Hello indietronic and welcome to AC.

As to your question well, it depends on your application and speakers.
The most universal version is 250 X 2 in 4 Ohms IMO.
Edit: 250 in 8 Ohms might be a better choice tho.

Regards
Mariusz

[Bemopti123]

The loot is in the mail.  Will also get parts from my partners in crime in Canada, PartsConneXion very soon. 

I need to arrange some sort of case for all the parts, maybe will carve out chunks of cut low grade ply in the garage, that was thinking about using for some never made speakers cabs. 

My loot consists of 2 500 watt boards, the heavier duty PS and the toroid.  The hardware will be some Furutech IECs, separate fuse holder, Cardas copper short binders, 14 gauge hookups in different colors, also got some Cardas female RCAs, heavy duty toggle switch.   

[roymail]

hello audiocircle forum and everyone! just joined extremely tempted by what i've already [34 pages!!] read here..

so my question is .. which one would you be your pick to drive ATC SCM11 ? 250 watts x2 @8ohm ? other ? has anyone tested one of these with ATC gear?

Blair, Niteshade Audio, knows his stuff and has high praise for this one:  250 watts/channel into a 4 ohm load, 125 watts/channel into 8 ohms.  This is the one I'm most interested in myself.

http://classdaudio.com/index.php/class-d-power-amplifier-250w-x-2-500w-x-1.html

[jkelly]

My 250 x 2 has been shutting down if I play it fairly loud.
Anyone else getting shutdowns?

[dewardh]

My 250 x 2 has been shutting down if I play it fairly loud.

What kind of speakers are you using, what is the speaker impedance?

What is "fairly loud"?

What power supply are you using?

Is the enclosure well ventilated?

Is the heat sink too hot to touch when it shuts down?

[jkelly]

What kind of speakers are you using, what is the speaker impedance?
Not sure DIY.

What is "fairly loud"?
Above normal listening levels.

What power supply are you using?
Large

Is the enclosure well ventilated?
Yes

Is the heat sink too hot to touch when it shuts down?
Not sure.

Just wondering if others have been able to shut it down.

Jeff

[Bemopti123]

Just wondering if others have been able to shut it down.

Jeff

Can you tell us the speakers you are using with these and what type of music you are partial to? 

For all that I know, it seems to me that some of these boards are spec for high watts, but perhaps these chips/designs are not as load invariant as some of the other designs out there.

[jkelly]

They are DIY "Scorpion" designed here on the board.

I'll also test with commercial speakers I have including
tough ones like Maggies.

The amp went into shutdown listening to rock.





I am thinking about adding a bigger heat sink or fan.

[Bemopti123]

Damn, as I suspect, it might be a issue of expecting high watts, but the board is not tolerant to load variance.  Might need a fan to be installed or how you said, better heat sinking.  I am thinking about using mine as a bass amp.

[steve k]

Damn, as I suspect, it might be a issue of expecting high watts, but the board is not tolerant to load variance.  Might need a fan to be installed or how you said, better heat sinking.  I am thinking about using mine as a bass amp.

This thread is getting too long. If you read my post #361, you'll see a picture of my 250/8 ohm amp which Tom has added additional heat sinks to allow it to run into a 4 ohm load. I'm driving the bass panels of my Maggie IIIA's with it quite successfully. It replaced a Hafler DH-500 heavily modded by John Hillig of Musical Concepts (255 wpc/8 ohms, 400 wpc/4 ohms).

JKelly, I suggest you talk to Tom. It sounds like you're getting either undercurrect or thermal shutdown.


steve

[Robert F.]

Hello all,
 I am new to this site. I found out about this from a link on the Parts Express site. I ordered a 250 watts/channel into a 4 ohm load, 125 watts/channel into 8 ohms kit yesterday. This will be my first amp project. Speakers I have are DIY Mini Statements found here http://speakerdesignworks.com/MiniStatements.html
They are what could be considered 5 ohm speakers and they are the best I have at the moment.  I hope this project pans out. If I get good results I will build a Tubelab Simple SE tube amp just for kicks. I was saving up to purchase two Emotiva UPA-1 mono block amps but I could not pass up this project. Thanks for the information in this thread as it has inspired me to do a DIY amp sooner than I hoped to.


Robert

[steve k]

Welcome aboard, Robert. It's a fun project and a great buy and I think you'll be surprised at the quality of sound. Good luck!
steve

[Steidl Guitars]

Finally have mine in place; it's sounds quite good driving my Dynaudio Contour 3.4s. 

First the guts, that I stuffed in an old computer peripheral box that I salvaged and sprayed black.



Second, in the rack.  Please forgive the lousy photo.



I inlaid the small bit of aluminum to give the face a feature, but it's a bit much, so I'll swap it out with a piece anodized black at some point. 

The wood is Australian blackwood, a close relative of Hawaiian koa. 

[inept]

Hello all,
 I am new to this site. I found out about this from a link on the Parts Express site. I ordered a 250 watts/channel into a 4 ohm load, 125 watts/channel into 8 ohms kit yesterday. This will be my first amp project. Speakers I have are DIY Mini Statements found here http://speakerdesignworks.com/MiniStatements.html
They are what could be considered 5 ohm speakers and they are the best I have at the moment.  I hope this project pans out. If I get good results I will build a Tubelab Simple SE tube amp just for kicks. I was saving up to purchase two Emotiva UPA-1 mono block amps but I could not pass up this project. Thanks for the information in this thread as it has inspired me to do a DIY amp sooner than I hoped to.


Robert

I am fairly new to this site also (been lurking for awhile).
I have the 250x2 500x1 amp driving my Mini Statements, the sound quality IMHO is excellent.
I had an Emotiva LPA-1 before I decided to assemble my own amp, and this classD amp is easily it's equal to my ears. My wife, who has better hearing than I do, says the class d sounds better.

Here is my mix and match amp, it was originally 4 TDA8924 modules 3 bridged 1 stereo for 5 channels, now 1 classd 250x2 4ohns and 2 TDA8924 modules for 5 channel.