Class D Audio, Who are these guys?

[Karl71]

Mark -

How does the sound quality differ from the Pass and Krell units with which you are familiar?

Regards,

Karl

[Mark Allen]

I think 5th element may be right on the thermal slug. I'm not sure what I was thinking there... musta been a brain f**t. I'll remove the thermal tape on mine next time I pull the sink off.

As for sound... At first listening it sounds very "solid state". After a long warmup the edge seems to smooth out a bit... I noticed this same thing today as I did yesterday. This amp very definitely sounds excellent after warm up especially if the recording is very good. The high end becomes very detailed after warmup and the sight edge seems to disappear. I am building the BPA 300 watt chip amp but thats a while off yet although I just about have all the other missing parts here. So hopefully by years end we'll be able to compare BPA-300 chip amp, This Class D amp, several of the Pass amps and the KSA-50 and 100. I just have to round up the old gang for a shoot out.

Mark

[mr_macgee]

Mark,

Not sure if this applies to this amp but what do you think about using instead a copper sink as a mod.?
Peter Daniel who makes beautiful chip amps found that "instead of aluminum, a copper bar would be more advantegous as it takes heat away better from the devices than aluminum" "I use copper in a Patek amp mostly to increase the amp weight, influence sonic signature a bit by controlling resonances". Just a thought as I see you had already removed the sink.


Thanks for your previous post's, I'm looking forward to any more comments or observations about the design, parts and sound.

I would be curious to how this amp will sound compare to a Hypex or ICE.

Cheers,

PS: "Arctic Silver" is a really good thermal compound.

[Mark Allen]

I'd have no problem with using copper but it's about 6 to 10 times more expensive then alumnium is. Copper conducts heat better but then we are not dealing with the amount of heat that even a class AB chip amplifier produces, are we? A nice largish copper CPU heat sink wold work really well! I scanned through the T.I. lit again and I believe I definately had the heat sinking thing wrong. Next time I pull the sink off I will very surely give it some arctic silver. I have some here some place... My wonderful wife who tolerates my eccentric electronics hobby has put up with the whole house being an electronics lab amnd things are well.... here and there and everywhere.

I have the amp on and am listening as I type... Sounds great but again very different from what I am used to. You might call it hyper clean... the detail is unbelievably clear but not exaggerated either. Female vocals have a smoothness that is uncanny! I am driving it with a Grounded Grid tube preamp at the moment until I get the 12B4 set back up. You live close enought to them to go have a look see... and perhaps get us a few pics for the thread? They are in Orange, CA. and apparently do allow walk ins. All you have to do is e-mail them... I bet you have a response within 5 min!
Edit.. P.S. This amp does need an hour plus time to warm up... I wonder why this is...?



Would utilizing this sink leave Peter Daniel in the dust???? Just kidding... Peter''s a great guy and I've built several of his projects...

[theAnonymous1]

Originally Posted by Mark Allen

This amp does need an hour plus time to warm up... I wonder why this is...?

Dare I say it's your ears (or rather what's between them) that need to warm up to the amp?

[mr_macgee]

I'll drop him a email and see about stopping by, yes I live somewhat close by but with the traffic around here it would almost be quicker to your house. I would think getting him on board could be a win-win for the DIY forum and himself. I did read somewhere that he was not aware of the audiophile community but was hoping to come up with a model for us eccentric hobbyist as he getting lot's of requests.

Yes the copper is more expensive but how much are we really talking about, a stock of .5-1lb max? I like the idea about adding mass to help control resonances and making the whole structure stiffer as an added bonus to the benefited cooling. Plus, it just sounds cool (no punt intended, well maybe).

My plan is find an ideal amp source for a small dual mono integrated with a remote for a pair of Totem Model One's with a 84 db @ 3.5ohm load, not exactly the easiest request. Peter Daniel and a partner have come up with a remote volume & input control that looks promising and not expensive.

The sound you describe is sounds a bit forward and digital especially since you already have a tube pre-amp hooked up to it.

[mr_macgee]

Edit: I just checked prices for square stock. My apologies, copper is indeed quite dear. Now I now why cities are having such a hard time from poachers pulling/ripping out copper wiring.

There were some ok prices on eBay:
http://business.shop.ebay.com/i.html...&_osacat=12576



With that sink you could crank the volume all the way to 11!

[Mark Allen]

Dare I say it's your ears (or rather what's between them) that need to warm up to the amp?

Definitely NOT my ears. After an extended warm up this thing sounds superb but before warmup sounds harsh. I've been doing some work in the other room so I don't have to listen too closley for a while. I have Krell KSA50 Clone Aleph 30 and pair of Aleph 2's I've compared it to.

My plan is find an ideal amp source for a small dual mono integrated with a remote for a pair of Totem Model One's with a 84 db @ 3.5ohm load, not exactly the easiest request. Peter Daniel and a partner have come up with a remote volume & input control that looks promising and not expensive.

Am not familiar with those speakers but they are pretty inefficient. Just give the amp time to warm up or leave it on all the time. I'm heading down to RaElco this morning to see if they have any largish surplus 48 or 50 volt switching power supplies to run this thing. Something with at least 10 amps or more...

You can always come join us here if the traffic is real bad. Pisser is that the traffic between Batstow and Las Vegas is pathetically slow at times. Once I get to Vegas I head north through Pioche and then through the West Desert to get back to SLC. It can actually be quicker and if you like desert country as much as I do then it's also more enjoyable.

Mark

[mr_macgee]

I guess my next question is what type of power supply would be best for this amp? Has SMPS made any inroads over a traditional toroid transformer? I noticed in reading that anecdotal opinion a toroid was preferred.



http://www.stereophile.com/standloud...820/index.html
Totem is a imaging monster but really needs a lot of good juice to shine for good bass and full sound otherwise it will sound shallow and thin. Paired with the right gear, they're sound awesome and very addicting. My next step would be to acquire Merlin TSM monitors.

[mr_macgee]

Here's an interesting read about a comparison test between several different D amps.

http://audiodesignguide.com/ClassD/classD.html