[Robert F.]

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.

Sounds as if I made a good choice. I like what you have done. This amp will be for two channel only ,however, if all goes well I may put together  a three channel setup to power the front end of my HT setup. My Speakers

[motosapien]

I'm currently building a pair of GR Research NX2 speakers.  They have low sensitivity of 85db if memory serves.  I'd like to try one of these amps.  I would be pushing it with a NAD pre which has an output impedance of 75.  There will also be a Grant Fidelity B283 Tube Processor after the pre.  Any obvious pitfalls besides not having a good tube pre?

[inept]

Very nice looking speakers.   Makes mine look like a "fisher price" product.  LOL

[steve k]

Excellent progress, gentleman!!  Beautiful woodwork Streidl! I'm glad you guys are hearing what I'm hearing. I'm not crazy after all although some would argue. 
steve

[pumpkinman]

Sounds as if I made a good choice. I like what you have done. This amp will be for two channel only ,however, if all goes well I may put together  a three channel setup to power the front end of my HT setup. My Speakers

Now there's a cabinet maker

[jkelly]

The amp went into shutdown listening to rock.

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

I have been using the Ebay case and if I take the cover off the amp
doesn't shut down.  The heat sink was extremely hot - untouchable.
So I think I will put a quiet Papst fan in their.

Can I pick off 12v for a fan off the board somewhere?

Jeff

[jtwrace]

I have been using the Ebay case and if I take the cover off the amp
doesn't shut down.  The heat sink was extremely hot - untouchable.
So I think I will put a quiet Papst fan in their.

Can I pick off 12v for a fan off the board somewhere?

Jeff

Hmm.  surprised it's that warm...  you can take the 12v off the board where it says "12V Fan".  Might look into one of these http://www.quietpcusa.com/Rasurbo-Ultra-Quiet-40x40x10mm-Computer-Case-Fan-with-3-Pin-Connector-P81C65.aspx

or

http://www.acousticpc.com/silenx_40_x_10mm_14db_pro_fan.html

[jtwrace]

The other thing you could do is run a standoff from the heatsink to the case top thus using the case as a HUGE heat sink.

[wushuliu]

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.

Well I jumpered the orange smd's and put 22uf dayton/jantzen caps in series w/ input. I'd say there's some improvement (some harshness but I'm sure that'll go away) but unfortunately I also put in a modded ebay dac and am so wowed by that it's hard for me to say how much a difference these new caps have made.

Upside is it's pretty easy to pop out those smd's and try it out for oneself. Only took a few minutes.

[shadowlight]

Well I jumpered the orange smd's and put 22uf dayton/jantzen caps in series w/ input. I'd say there's some improvement (some harshness but I'm sure that'll go away) but unfortunately I also put in a modded ebay dac and am so wowed by that it's hard for me to say how much a difference these new caps have made.

Upside is it's pretty easy to pop out those smd's and try it out for oneself. Only took a few minutes.

Which ebay dac?

[Mariusz]

Well I jumpered the orange smd's and put 22uf dayton/jantzen caps in series w/ input. I'd say there's some improvement (some harshness but I'm sure that'll go away) but unfortunately I also put in a modded ebay dac and am so wowed by that it's hard for me to say how much a difference these new caps have made.

Upside is it's pretty easy to pop out those smd's and try it out for oneself. Only took a few minutes.

X2

yeah, any links?

I was looking at few ready boards (upsampling and NOS)
but can not decide which one to try.

THX

Cheers
Mariusz

[wushuliu]

X2

yeah, any links?

I was looking at few ready boards (upsampling and NOS)
but can not decide which one to try.

THX

Cheers
Mariusz

The most documented would be the gigawork kit. Upsampling board, usb, etc. Comes with a very high quality transformer as well.

http://cgi.ebay.com/Gigawork-24-192-Up-sampling-DAC-DA-CONVERTER-w-USB-kit_W0QQitemZ120474001273QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1c0ccf5f79#ht_9175wt_996

Similar board but cheaper, with no usb or upsampling or transformer.

http://cgi.ebay.com/NEW-BIG-24bit-192Hz-HI-FI-DAC-DIY-KIT-ASSEMBLED-MODULE_W0QQitemZ140389033636QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item20afd6a6a4

There's a 250 page(!) thread on these at diyaudio and many more threads on sifferent forums. But the short of it is:

Stock/opamp upgrade: better than dacmagic and up. Bargain as is.

Transformer outputs: bypass opamps and use transformers for the output = nirvana.
This mod is actually very simple.





I opted for a middle ground because the transformers can get a little pricey: I just put in different opamps and either removed electrolytics or replaced them w/ polyprop caps.

I don't have experience w/ high end dac's but I can't imagine that they can bring me much closer to the music than this. Maybe different flavor, soundstage, etc. I can't imagine what level the transformers would take it to. Anyhoos there are many, many threads out there with the same conclusion: phenomenal value.

I can start a short thread with some pics, as I don't want to take this off topic...

[jtwrace]

I can start a short thread with some pics, as I don't want to take this off topic...

Go for it!

[jkelly]

Hmm.  surprised it's that warm... 

Are other boards not running hot?  Maybe mine has an issue.

I had good luck with these fans when I was modding the Carver ZR1600:

http://www.endpcnoise.com/cgi-bin/e/std/category=Papst_Fans.html


BTW these amps sound much better with hours on them!

Jeff

[roymail]

What does Tom have to say about the heat issue? 

[jtwrace]

my amp is barely warm

[roymail]

Is it exposed to the air, enclosed in a case or have a fan?

Does yours run only warm under a load?

Thanks!

[wushuliu]

Is it exposed to the air, enclosed in a case or have a fan?

Does yours run only warm under a load?

Thanks!

My IR amp gets warm but it's never shut down and I've used it unventilated. The last time I read about an overly hot amp was on diyaudio. The person had the 600w amp and I think it eventually fried. Tom sent him a new board. So get in touch w/ Tom stat.

[DougSmith]

Are other boards not running hot?  Maybe mine has an issue.

Mine runs quite cool, even with a 35V transformer, but I am running 8 ohm, high efficiency drivers.  What is are the impedance and efficiency ratings of your speakers?

[jkelly]

I am in contact with Tom who is very willing to check it out.
Just got to get to Monday!

Thanks for all the help and suggestions.