[matt_garman]

I even went bare-minimum on my design: combined fuse+IEC, no power switch, two XLR inputs and four speaker binding posts.

Hey Matt, are you running a fully balance system?  There is no mention of SE rca inputs.  If the SDS-470 sounds no different than a QSC pro amp, I doubt this thread would be almost 150 pages.  Not sure what's holding it back. 

Yes, the Emotiva XDA-1 has both fully balanced XLR outputs and single-ended RCA outputs.  I'm using the former.

Regarding the suggestion that the SDS-470 sound quality is similar to the QSC: I didn't mean this as a slight in any way.  In fact, I meant quite the opposite.  I know there is a debate as to whether or not pro amps can compete with "audiophile" amps.  I personally think they can.  (And there is no debate that, strictly in terms of watts per dollar, pro amps always win.  This is the cheap and cheerful forum, after all.  )  That's a long-winded way of saying I do believe that the QSC sounds excellent.  So to say the SDS-470 is on equal footing is---coming from me---a major compliment.

Having said all that, keep in mind, those were my initial impressions only.  Time spent with the amp thus far is minimal (relative to the QSC).  And as of last night, I think I'm starting to pick up on the nuances between the two amps.

To elaborate on the "cheap and cheerful" point: on this consideration, I think a pro amp is a perfect comparison to the Class D Audio amps.  That is, both are trying to "cheat the system", so to speak; both try to get audiophile quality at a lower price point.  To get an "audiophile" amp that is comparable in terms of wattage to the QSC or CDA, you'd have to spend at least $1.5k, probably more like $2k.

Anyway, I've always lingered in the "super cheap" category; only this year have I really started to make inroads into what would probably be called the "mid-fi" category.  The only dramatic improvement I've ever seen with a component switch is when I replaced Energy RC-30 speakers with the Salk Songtowers.

Glad you're having fun.

Absolutely!  Just to reiterate: I don't want to give anyone the wrong impression, I think the SDS-470 is great.

It's entirely possible that I just have unrefined hearing. 

p.s. I can't help but argue the pro amp thing a little bit: using thread length as an indication of how good an amp is, then pro amps in general are good according to this 160 page AVSForum thread.

[roymail]

Matt, appreciate your additional remarks and impressions.  Everyone needs to keep in mind that audio is a very subjective hobby.  If you're pleased with the sound, that's all that matters. 

[matt_garman]

I should also add that my room and overall setup/positioning leaves a lot to be desired.  I don't have a dedicated listening room---it's just our living room.  And it's a massive "great" room, all hardwood floors.  We have one rug, and minimal window dressings, but no other sound-specific treatments.  Here's a link to a schematic of our floor plan.  Look at the lower-left where the "media console" is; the speakers flank either sides of this.  As you can see, it's a corner placement, generally considered a no-no for good 2-channel sound.  Also, the speakers are fairly close together, especially when the distance to any possible listening position is taken into account.  Given all these constraints, I think there is a definite ceiling to how good any component can sound.  What that limit is, I can't say, but I'm sure it exists.

[pelliott321]

Matt I do not feel you need to make excuses for your comments about ClassD Audio products.  I got blasted for not jumping on the band wagon.  My ClassD amp has been junked and I am using the PS for something else.

[wushuliu]

Matt I do not feel you need to make excuses for your comments about ClassD Audio products.  I got blasted for not jumping on the band wagon.  My ClassD amp has been junked and I am using the PS for something else.

because out of 144 pages there are only a handful of people who did not like their amps and a few also needed some component matching to get the best from theirs, so maybe 'blasted' should read 'non-stop suggestions', for which this thread is indeed guilty.

Wow. Junked. I assume it's broken. If not, what a shame. I'm sure someone else could have a use for it.

[toxteth ogrady]

No offense Pelliot, but why is it necessary to beat a dead horse?

You have notoriously difficult speakers to drive and you bought the wrong amp to drive those speakers. This has been said to you repeatedly. You clearly have a mismatch of components and at the very least you should listen to the amplifier with a buffer in place before making silly remarks about jumping on the bandwagon. There are some very generous members on Audiocircle that I'm sure would be willing to lend you a buffer to try out. I would lend you mine if it wasn't integrated with my LDR. If it's too much work then just sell the kit and move on.

[rajesh]

No offense Pelliot, but why is it necessary to beat a dead horse?

You have notoriously difficult speakers to drive and you bought the wrong amp to drive those speakers.

Irrespective of the reason for amp not sounding up to the expectation, I agree to what has been highlighted.

[StevenZ]

Hey guys, I've got a quick question for y'all.  Last night I took my SDS-224 over to a friends house to listen on his Usher TOTL speak.ers (not the diamond or BE dome, the older model silk dome). So we popped in some Nat King Cole and cranked it up.  Keep in mind his speaker's nominal impedance is 8 ohms, which according to my amp's power chart cranks out 60 watts per channel.  Now, another thing about his speakers, they're 90db efficient.  So back on track, we're listening to it, and things are sounding fantastic, then all of a sudden I notice the right channel cutting in and out.  Just the right channel, so I walk up, crack the top off the amp and notice that the right channel is dropping out and the yellow LED's are lighting up, then switching back to blue.  I touch the heat sink to see if maybe it's overheating, dead cold.  What was happening?  Was I just driving the amp too hard?  I didn't hear any noticeable distortion at all.  In fact it was the best I've ever heard the amp sound.  Can someone tell me what was going on with my amp?

Just a little bit more information, he was providing a signal to the amp with a Naim preamp, and a Sony XA5400es. Great equipment, though with the gains set exactly alike, how could it be that one channel was dropping out constantly?  I rechecked all connections and everything is solid.  What am I missing?

-Steven

[roymail]

Either call or email Tom at Class D Audio about the problem.   I'm not sure what's going on.  I don't recall reading about that particular issue.  Let us know the outcome.  Thanks.

[TrungT]

Steven
Yellow light on one channel - Check out the DC voltage from the PWR supply board to main board, +/- voltage.

[Nick77]

Either call or email Tom at Class D Audio about the problem.   I'm not sure what's going on.  I don't recall reading about that particular issue.  Let us know the outcome.  Thanks.

I was thinking the same thing but also wonder what power supply you have.
What gauge wire are you using??

[StevenZ]

I have the power supply that came with the kit.  I just sent Tom an email regarding this problem.  I have the same AWG wiring as the transformer uses going to the amp board.  Should I use a larger  more robust wire?  Also, I haven't checked any values as I don't have a DMM.  I feel I must mention this, now since you guys suspect a power supply problem.  When I power down the power supply, one set of LED's goes off long before the other set.  Would it be safe to assume that the set that goes off quicker is the right channel, the channel that's giving me grief?

I hope Tom replies.  My last request for help sent to him went unanswered.  I hope he doesn't disregard this one and actually answers me back. I left him my phone number as well just in case that's his preferred method of contact.  I really love the amp, but perhaps I got a dud power supply and/or amp board.  We'll see how this pans.

[Nick77]

I use a high quality 16awg solid core wire twisted into a double run for wireing each post. Dont want any bottlenecks. 

Yours comes with the larger ps, thats a good thing. My SDS254 has 60k capacitance and sounds really good, never had any issues.

[mikeeastman]

I had same problem with my battery powered Dodd class d. Tom said low voltage cut off was set to high. I sent amp to Tom who readjusted to lower voltage and it worked fine after that.

[mboxler]

Hi Steven...

I had the same issue when I moved my temporary setup to a more permanent one.  I ended up using spade connectors to and from the power supply, started it back up, and haven't had the issue since.  I too thought all the "tinned" bare wire connections were solid, but I wonder if the spade connectors are the key (?).

Mike

[rajesh]

all of a sudden I notice the right channel cutting in and out.  Just the right channel, so I walk up, crack the top off the amp and notice that the right channel is dropping out and the yellow LED's are lighting up, then switching back to blue.  I touch the heat sink to see if maybe it's overheating, dead cold. 

What a coincidence!! When I paired the amp with an old NAD1020A Pre-amp, the same thing happened to me all the three times I tried playing it. The pre-amp was not at fault as it played fine with another power amp I played it with. The heatsink doesn't appear to have been overheated. It remains just warm.

That's when I decided to put it on the attic.

[StevenZ]

Rajesh, I won't jump to conclusions. Anything could be the problem.  What I'll do is run double wiring from the PS to the Amp board to eliminate the possibility that there's any bottle-necking going on regarding current supply. I talked with Tom earlier today and he said that he won't know without looking at the actual unit.  He wants me to send it back to him next week so he can evaluate it in person. He guaranteed me that everything will get worked out. 

His reply was very quick and I feel confident he will take care of the situation one way or another.  I'll also take more precautions and solder up some larger AWG wiring to the speaker terminals as well. 

I'll keep you guys posted. 

[wushuliu]

I wish Tom focused more on the customer service, even if it meant fewer amp choices (I think there are too many and too little info provided about each at this point).

[rajesh]

Rajesh, I won't jump to conclusions. Anything could be the problem.

Actually StevenZ, my post was a supplementary to my earlier posts which, I've linked below:-

1. http://www.audiocircle.com/index.php?topic=76400.msg931340#msg931340

2. http://www.audiocircle.com/index.php?topic=76400.msg936492#msg936492

3. http://www.audiocircle.com/index.php?topic=76400.msg936546#msg936546

4. http://www.audiocircle.com/index.php?topic=76400.msg936676#msg936676

5. http://www.audiocircle.com/index.php?topic=76400.msg936868#msg936868

What I'll do is run double wiring from the PS to the Amp board to eliminate the possibility that there's any bottle-necking going on regarding current supply.

OK, fair suggestion. I'll take it out from the attic and test it again. First through a potentiometer and later through a tube pre-amp. Will post the results here.

I talked with Tom earlier today and he said that he won't know without looking at the actual unit.  He wants me to send it back to him next week so he can evaluate it in person. He guaranteed me that everything will get worked out. 

His reply was very quick and I feel confident he will take care of the situation one way or another.

You are lucky is all that I can say. Probably my bad luck that I'm located so far away. He didn't bother to reply to my mail regarding the heating problem (of which I had reported in one of my earlier posts linked above) So I decided not to bother him ever again.

[guest1632]

I finally completed my SDS-470 kit build this past weekend.  I thought I'd post my initial impressions.

First: on the first test, I powered it on, but got no sound.  I noticed the on-board LEDs indicated "Left Off" and "Right Off".  The power supply lights were on.  I used my DMM, and verified that I had DC going to the amp board.  Nothing changed on the preamp side, and the music was playing.  I was about to come here to ask for help when I noticed the little built-in "on/off" switch on the side/bottom of the amp board!  I switched it on, and I got music!  Classic ID-10-T error on my part.


Anyway, as for the sound quality discussion (what everyone is probably most interested in).  On the very first listen, as I mentioned briefly above, I really couldn't tell much difference between the SDS470 and the RMX2450.  On a few rare occasions, I thought I've heard a little bit of sibilance... but lately, I haven't heard that.  Not sure if I imagined it or not.  Also: depending on the input gain setting of the pots, I can hear a very faint hiss coming from the speakers when my ears are a few inches away or less (and there is no music playing).  Adjusting the gain fixes this though.

I don't know if my ears are getting used to the unit, or it's being "broken in" (a concept I'm not sure I really believe in anyway), but last night I felt like the amp had a little different "character" from the QSC.  Is it better?  Maybe.  It does sound great, there is no doubt about that.  I'm just not sure if the difference is all in my head or not.  It's too annoying to keep switching between the two amps, so I try to just go from memory (I'll be the first to admit I have an awful memory ).  But last night, I thought I was experiencing a bit of what I've read so much about on this thread, particularly increased instrument separation and a bigger soundstage.

Ultimately, I just need to spend more time with it.  But so far so good.  Next step I believe is to give a SMPS a try.  If that proves successful, then I might move forward with the monoblock idea.  At a minimum, I would spring for a professionally machined and finished enclosure.

I'll try to find some time to post pics.

Actually, your next little project should be the elimination of the two pots, in favor of two 1% resistors. You might see what your QSC is. If the standard for the QSC is 27DB, then if memory serves me right a 1.2? resistor for each channel should make a difference. Several pages back there is a chart with the correct resistor ratings to use. The pots Tom uses are cheap, and replacing them fixed with resistors will have a dusk and night result, that you might be able to hear. Just a suggestion or two.

If you put/mounted  those pots in your case, a search on the net you can find caps to cover the holes they made.

Ray Bronk