Sure-Electronics.com class d amps - Page 3

audio1st · 9th November 2007, 01:06 PM

I removed the heatsink on my amp and yes, it is just a metal plate on show, no marks. No paste was used so no mess.
If you use the terminal block input terminals, then you bypass the 0.7uf input caps. No caps via this input..
There seems to be a constant background hiss from all channels, at all volume settings. I have tried different power supplies and it is still there..I dont think, IMHO, it is going to be a "hifi amp"

..

Bearman · 9th November 2007, 09:29 PM

I bet it is those inductors making the hiss. I wonder if they were shielded, it would make some difference.

Neil Davis · 14th November 2007, 02:12 AM

Quote:

Originally posted by Ouroboros
Almost certainly a Sanyo STK428-xxx 'Ice-Power' module.

No such luck. Mine finally came today, so off went the heatsink and then on to desoldering the pins.

Here is what it says on the underside of the chip:

SDA-754
SS 07 08 31 15: 09: 25 5128
AC/HOT OK JUN SUN OK

My guess is that it is a module made for them by Monolithic Power. Sure-electronics has an amp board with the MP7220, and this looks like it could be a module made from 4 MP7782's. The MP stuff uses a single supply with analog input, and MP is one of the few that provides that combination.

kellyinvestor · 14th November 2007, 02:45 AM

Quote:

Originally posted by Neil Davis

No such luck. Mine finally came today, so off went the heatsink and then on to desoldering the pins.

Here is what it says on the underside of the chip:

SDA-754
SS 07 08 31 15: 09: 25 5128
AC/HOT OK JUN SUN OK

My guess is that it is a module made for them by Monolithic Power. Sure-electronics has an amp board with the MP7220, and this looks like it could be a module made from 4 MP7782's. The MP stuff uses a single supply with analog input, and MP is one of the few that provides that combination.

Umm, did you listen to it first? Good, bad?

Neil Davis · 14th November 2007, 03:02 AM

Quote:

Originally posted by kellyinvestor

Umm, did you listen to it first?

Of course not. I'm an engineer.

But I think I was able to put it back together OK (one broken pin that I was able to fix). I'll clean off the solder flux tomorrow, check for damage and try it out sometime in the next few days.

buzz1939 · 14th November 2007, 02:17 PM

Datasheet PDF for the MP7782

and for comparison

Sure PDF on the amp

Neil Davis · 16th November 2007, 04:37 AM

I got the amp back together and hooked it up to a 12V supply to start out. The switching frequency is fairly high--up around 450KHz. That's higher than what Philips uses and less than Tripath, but it's in the range that MonolithicPower uses (400KHz-600KHz).

There's a fair amount of constant "hiss" in all channels that is probably due to the high gain of the module. I haven't measured the gain, but it doesn't take much input to saturate the amp. I tried bridging one of the 56K resistors with another 56K to cut down the gain, but it didn't seem to make any difference in the hiss. It's typical amplifier noise, but definitely more than what you hear from an LM3886 amp with Av=20. Shorting the input to ground doesn't make it go away, and it doesn't seem to be from the power supply (additional capacitance didn't help). The hiss level is different for each channel...hmmm.

I measured one of the output coils--looks like 12uH.

I'll give the amp a workout with real speakers later on, but based on what I've heard so far I expect the quality to be good.

xaudiox · 16th November 2007, 04:52 PM

Quote:

Originally posted by Neil Davis
I'll give the amp a workout with real speakers later on, but based on what I've heard so far I expect the quality to be good.

Looking forward to your results.. I'm also planning to get one of this..

regards

SQ Kid · 16th November 2007, 07:34 PM

I am also slightly interested in maybe getting a couple of these for a quick and easy home theater amp. The hiss mentioned, is it quite noticeable? Or is it something more along the lines of what you would here from an off-the-shelf reciever (like pioneer, sony, yamaha, etc)? I'm not looking for the holy grail, just something thats 4ohm stable for not too much cash.

h82missafire · 16th November 2007, 08:33 PM

Hello, I have one of the 2 channel modules coming and Sure said in a reply yesterday that a new batch is being built and will ship asap.

Question for anyone....would a 24v 6a laptop barrel connector power supply be adequite in both powering and connecting?

Looks like a DC female barrel jack on the board.

Thanks

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9th November 2007, 01:06 PM	#21
audio1st diyAudio Member Join Date: May 2005 Location: Foxton, CAMBS..	I removed the heatsink on my amp and yes, it is just a metal plate on show, no marks. No paste was used so no mess. If you use the terminal block input terminals, then you bypass the 0.7uf input caps. No caps via this input.. There seems to be a constant background hiss from all channels, at all volume settings. I have tried different power supplies and it is still there..I dont think, IMHO, it is going to be a "hifi amp" ..

9th November 2007, 09:29 PM	#22
Bearman diyAudio Member Join Date: Apr 2005 Location: Utah	I bet it is those inductors making the hiss. I wonder if they were shielded, it would make some difference.

14th November 2007, 02:17 PM	#26
buzz1939 diyAudio Member Join Date: May 2007	Datasheet PDF for the MP7782 and for comparison Sure PDF on the amp

16th November 2007, 04:37 AM	#27
Neil Davis diyAudio Member Join Date: Dec 2004 Location: Reston, Virginia	I got the amp back together and hooked it up to a 12V supply to start out. The switching frequency is fairly high--up around 450KHz. That's higher than what Philips uses and less than Tripath, but it's in the range that MonolithicPower uses (400KHz-600KHz). There's a fair amount of constant "hiss" in all channels that is probably due to the high gain of the module. I haven't measured the gain, but it doesn't take much input to saturate the amp. I tried bridging one of the 56K resistors with another 56K to cut down the gain, but it didn't seem to make any difference in the hiss. It's typical amplifier noise, but definitely more than what you hear from an LM3886 amp with Av=20. Shorting the input to ground doesn't make it go away, and it doesn't seem to be from the power supply (additional capacitance didn't help). The hiss level is different for each channel...hmmm. I measured one of the output coils--looks like 12uH. I'll give the amp a workout with real speakers later on, but based on what I've heard so far I expect the quality to be good.

16th November 2007, 07:34 PM	#29
SQ Kid diyAudio Member Join Date: Apr 2003 Location: MA	I am also slightly interested in maybe getting a couple of these for a quick and easy home theater amp. The hiss mentioned, is it quite noticeable? Or is it something more along the lines of what you would here from an off-the-shelf reciever (like pioneer, sony, yamaha, etc)? I'm not looking for the holy grail, just something thats 4ohm stable for not too much cash.

16th November 2007, 08:33 PM	#30
h82missafire diyAudio Member Join Date: Sep 2007	Hello, I have one of the 2 channel modules coming and Sure said in a reply yesterday that a new batch is being built and will ship asap. Question for anyone....would a 24v 6a laptop barrel connector power supply be adequite in both powering and connecting? Looks like a DC female barrel jack on the board. Thanks

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