$175 Class D amp--120 wpc

justd · « **Reply #3360 on:** 30 Jun 2012, 02:26 pm »

actually i wanted to fit 4 amp modules in 17" space to have a provision for 7.1 setup if i wanted to in the future. That is why i ended up quite tight.

I had sent the photos to Tom as well and he was OK with the layout. As far as my humming is concerned i have the following symptoms.

1) when i switch on the amps with speakers connected and no processor connected. I get a very slight hum from the speakers which i have to have my ears very very close to the speakers to hear it.

2) when i attach RCA interconnects to the Amp the hum increases to the point that i can hear it from 4-5 feet away

3) if hold the hold the negative of the two RCA channels with either of my thumbs the hum is greatly reduced

4) when i connect the interconnects to the Processor and switch it on, the hum does decreases a little bit.

5) when i play something on the bluray player the hum increases dramatically. When i stop it reduces to previous levels after a fraction of a second. If change the volume on the processor the hum level does not change it remains the same.

6) if i switch of the processor the hum increases to a very high level.

I have connected all my equipment to all my equipment to a single belkin powerstrip. The ground is working. i got it checked. the equipment right now connected to the strip is.

Two classdaudio amps connected through single power supply ( the third amp is disconnected)
one behringer amp for the subwoofer
Emotiva umc-1 processor
one sony bdp s590 connected through a 220-110 transformer

1. use umc-1 without ground
2. use claasd amp without ground
3. remove the behringer amp

Doing the above does not make any difference.
I tried the amps with a different power socket, The same pattern of hum occurs.

could braiding of the power lines be a problem? I was reading somewhere that toroidal transformers can also induce hum. Any help will be appreciated.

mboxler · « **Reply #3361 on:** 30 Jun 2012, 03:38 pm »

3) if hold the hold the negative of the two RCA channels with either of my thumbs the hum is greatly reduced

Are these the input RCA's or the output RCA's?

If you are referring to the output RCA's, and have some extra speaker wire, I'd run one end straight to the amp (taking the RCA's out of the loop).

Are you using very efficient speakers? My Klipshorn's will buzz slightly a foot from the tweeters, but not at listening distance.

Mike

justd · « **Reply #3362 on:** 30 Jun 2012, 04:12 pm »

RCA inputs which go into the amp from the processor to the amp. I hold the negative of the interconnect RCA connected to the amp, without connecting to the processor.

i am running Mirage OMD 15. L/R Sensitivity: 87 dB from 500 Hz to 2 kHz.

mboxler · « **Reply #3363 on:** 30 Jun 2012, 07:02 pm »

Sorry...running out of ideas.

Almost sounds like a bad connection, if touching it solves the problem. I tinned the end of the wire before inserting it into the amp input (sometimes needing pliers to flatten the end so it would fit into the input terminal). I also make sure 1/16" or so of bare wire is exposed, just to make sure I'm not clamping down on the wire insulation.

Another thought. Did you use heat shrink tubing on each of the wires you soldered to the input RCA?

Good luck!

Mike

rajacat · « **Reply #3364 on:** 30 Jun 2012, 08:24 pm »

Has anybody directly compared the Class D SDS amp to the ICEpower 125ASX2? http://app.audiogon.com/listings/icepower-125asx2-diy-kit-assembled-mono-block-550w-am--3

...Roy

Ajani · « **Reply #3365 on:** 30 Jun 2012, 08:48 pm »

Quote from: rajacat on 30 Jun 2012, 08:24 pm

Has anybody directly compared the Class D SDS amp to the ICEpower 125ASX2? http://app.audiogon.com/listings/icepower-125asx2-diy-kit-assembled-mono-block-550w-am--3

...Roy

Mellifluous has both the 125ASX2 and the SDS-254. He prefers the 125ASX2.

http://www.audiocircle.com/index.php?topic=100249.msg1101726#msg1101726

wushuliu · « **Reply #3366 on:** 1 Jul 2012, 01:10 am »

New mini amp out! Curious as to what the amp chip is. There's also new 4 channel complete amp available.

http://classdaudio.com/class-d-audio-amplifiers-1/mini-class-d-audio-power-amplifier.html

rajacat · « **Reply #3367 on:** 1 Jul 2012, 04:39 pm »

Hmm.... For those of us with very efficient speakers, I wonder how the sound quality of the mini amp, given it's power constraints, compares to the much higher powered versions. Battery power would eliminate the noisy influence of the power grid. Also the mini amp would be operating in it's sweet spot vs. using a much higher powered amp which would be idling most of the time.

I'm thinking that two of these in bridged mode, battery powered, would provide nice clean 30w/ch for efficient speakers at a very low cost. My current 25w monoblocks hardly ever get past 10 o'clock on the volume control.

Red Wine Audio has been using battery power for years for their well reviewed and modestly powered amps.
Dodd Audio also has some battery powered monoblocks that have been well received.

...Roy

srb · « **Reply #3368 on:** 1 Jul 2012, 04:45 pm »

The Mini Amplifier might be a good fit for that portable DIY boombox/iPod speaker.

Steve

praedet · « **Reply #3369 on:** 2 Jul 2012, 03:28 pm »

I like my SDS on a battery for sure...

rajacat · « **Reply #3370 on:** 2 Jul 2012, 06:23 pm »

Quote from: praedet on 2 Jul 2012, 03:28 pm

I like my SDS on a battery for sure...

Was your battery powered implementation discussed somewhere in this huge thread? I'm curious how you used batteries to come up with the specified 40+ volts. Did you connect a number of 12V batteries in series?

TrungT · « **Reply #3371 on:** 2 Jul 2012, 06:35 pm »

Battery power supply
http://classdaudio.com/power-sppplies/12v-dc-switching-power-supply-500-watt-car-audio.html

mboxler · « **Reply #3372 on:** 2 Jul 2012, 07:11 pm »

Looks like the "Mini D" runs straight off a 12V battery...perhaps the same battery powering my Dodd preamp??? Hope Tom adds more specs to his website.

TrungT · « **Reply #3373 on:** 2 Jul 2012, 07:20 pm »

Yes, it should work.
"The amplifier runs from a 10V to 24V DC power supply or Battery"
One is on the way to me.

rajacat · « **Reply #3374 on:** 2 Jul 2012, 07:57 pm »

Ah I see.... a separate board to convert the 12V to ~40V. How does the SQ compare to the stock linear PS boards?

Quote from: TrungT on 2 Jul 2012, 07:20 pm

Yes, it should work.
"The amplifier runs from a 10V to 24V DC power supply or Battery"
One is on the way to me.

I'll be eagerly awaiting your review.

mboxler · « **Reply #3375 on:** 2 Jul 2012, 08:35 pm »

+1

Wasn't it Paul Klipsch himself that said (paraphrasing) "What the world needs is a good (1)5 watt amp." ?

srb · « **Reply #3376 on:** 2 Jul 2012, 10:32 pm »

Quote from: mboxler on 2 Jul 2012, 08:35 pm

Wasn't it Paul Klipsch himself that said (paraphrasing) "What the world needs is a good (1)5 watt amp." ?

What he actually said was "What this country needs is a good five-watt amplifier" (which was an alteration of an earlier famous quote "What this country needs is a good five-cent cigar").

Of course Paul's quote has to be taken in the context as being from someone who was building and selling a 105dB loudspeaker.

Steve

maxitonus · « **Reply #3377 on:** 9 Jul 2012, 07:51 am »

Hi gentlemen,
I recently methodically compared three amps,one expensive, and excellent amp, tubed with 8XKT120,the DEVIALET amp,which seems to be recognized as a top performer, and my SDS470 (mods:removed the asymmetric RCA input,removed the wire which allows the led included in the on/off switch to be lighted)(no mods of the caps).
The results show that the three above ones are in the same sound quality league, the differences between them being less than the magnitude when changing some cables.
The tubes one has an euphonic charachter, very pleasant,but after a (long) while,some lack of surprise appears in my mind, the DEVIALET is excellent, gives the impression that it's very quick and uncolored since the mediums are very slightly recessed, the piano notes are excellent,but if the digital message is not perfect,dont account on it to forgive .., and the SDS is fully comparable to both previous ones,the sound is absolutely excellent but under the condition all the cables have been optimized in order to tune as perfectly as possible the complete system.

I planned to upgrade the caps to panasonic's, but the current result is soo good that i dont intend anymore to do it.

I have NO personal interest for which concerns my information,i own (also) the tubed amp, so i have a free choice, and i choose the SDS, but i donot criticize the tubed once since it is really good also,but i am slightly more "disturbed" and awakened when listening to the SDS, this is why i finally prefer it..But other audiophiles might very well prefer the tubed one, this is in the subjective domain.

I formerly thought that the treble (or medium-treble) might be purer with the tubed amp, but finally the difference of purity is not really relevant, all is depending upon the purity of the digital system incl. the dac.
I will let all of you informed about future confirmations of the above conclusions.

rajacat · « **Reply #3378 on:** 9 Jul 2012, 07:03 pm »

Quote from: TrungT on 2 Jul 2012, 07:20 pm

Yes, it should work.
"The amplifier runs from a 10V to 24V DC power supply or Battery"
One is on the way to me.

Any news on this?

TrungT · « **Reply #3379 on:** 9 Jul 2012, 07:30 pm »

24V sound very good,and yes, it's a keeper.
I'm still "breaking in" new S/O Mundorf caps on the speakers, 2 more weeks 24/7 to go.
Will move to a metal chassis soon.