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Paging "mwhouston"! IT'S ALIVE!!!! The Class D Audio SDS-254 LIVES!!!

12.4.185.2
Posted on May 15, 2015 at 06:09:49
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001



Finally got around to building up the SDS-254 kit the other night, and have been passively (meaning not paying much attention) letting it run over the last three evenings.

Things I have noticed with this amp- VERY solid bottom end. The kind of bottom that amps like Krell and Bryston are noted for. Midrange IS very tube-like, with that excellent 3-D, disappearing loudspeaker act going down. The top end is as you stated, with my thoughts leaning towards very tight and detailed, not edgy.

I'm not sure just how long a real burn in this thing needs, as the difference in listening over the last three nights given to different impressions each time, ranging from very bright sounding (first night) to mellow and authoritative (second night- changed from an 18awg power cord to a 14awg), to extremely quick on dynamic swings (last night). I played some treble-roasted 80's dance mix stuff (Depeche Mode, Frankie Goes to Hollywood) and wasn't killed by the top end- it was very focused and listenable while very extended. That is something that ONLY my old ARC D76a was capable of doing, lacking only in a little of the very top end extension and focus...

While there were a few stumbling blocks to the kit- there are next to NO real instructions included, which are sorely needed for some aspects of this kit.

I spoke via email to Tom at Class D Audio, and he is desperately trying to get his website updated, as well as a whole range of PDF manuals together. He's not a one man show, but at the same time, he is still a "mom and pop" operation.

I'll be posting a full review in a few weeks (maybe even a month) once I get a handle on this (and some serious listening).

Cheers,
Dman
Analog Junkie

 

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RE: Paging "mwhouston"! IT'S ALIVE!!!! The Class D Audio SDS-254 LIVES!!!, posted on May 15, 2015 at 06:58:50
AudioSoul
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Posts: 4594
Location: north central AZ
Joined: July 9, 2005
If this amp is making CD's that typically have a hot top end and making them sound listenable then the amp is changing the sound (typical of class D amps) then it is not neutral. To me that's another class D fail....

 

Well, let's define this a little bit more... , posted on May 15, 2015 at 07:58:04
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 Speed in an amplifier (or anything in the rig) trumps all in my book, and I've heard a lot of cartridges/'tables/preamps/amps/speakers that just don't resolve the treble enough; the result (to my ears) is harshness and fuzziness to the detail. That drives me away from CD (and most digital) in the first place. I've also heard various cartridges/'tables/preamps/amps/speakers that do it really well too. The ones that do it well give me the impression of live music rather than hi-fi.

With that being said, the SDS has a top end, that is not unlike the tube stuff (and yes, even good solid state), again to MY ears, that is focused to the point that you can hear cleanly the transient attack and decay of cymbals or percussion. It isn't etched, nor is it subtle. It is reminiscent of real percussion instruments. That to me IS heading in the right direction (neutrality).

Of course, if the source (digital OR analog) itself sucks, there is nothing down stream that can fix it- only add a bandage, as you suggest. That isn't a good thing, and I concur with your opinion of that. Blurry resolution of that top end will sound like crap. Good gear will resolve it.

That is what I'm hearing with this amplifier- good resolution from top to bottom. I would be stupid to say it better than (insert your favorite cost-no-object GOOD amp here). But in the range I'm talking (remember, it was only an outlay of less than $550), it is shaping up to be damn good!!

Cheers,
Dman
Analog Junkie

 

Looking good; thanks for your comments, posted on May 15, 2015 at 12:01:40
Feanor
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  Since: March 12, 2004
 My own experience with the SDS-258 is similar: it is an extremely good sounding amp with due consideration to its very reasonable cost.

Driven my ARC LS9 preamp and driving my Magneplanar MG 1.6QR's the SDS-258 amp is very resolving with precise but slightly lean bass. The top highs are NOT etched or grainy, however on SOME recording they can be bright. In fact the highs are quite dependent on the recording quality: the cleaner the recording the better the sound. The SDS-258 doesn't cut much slack for recordings that aren't clean.

I agree that the SDS mid-range is not "grey" or "bleached"; (this was to an extent true of my Bel Canto Tripath-based eVo2).

In comparison to my Pass Labs X150.5, the SDS-258 lacks "body" in the bass, doesn't quite have the Pass' holographic imaging, and doesn't have quite the PRaT which is noticeable, e.g., in case of piano and percussion instruments. But note that it's on the top-end that the SDS-258 gives up the least to the Pass.


Dmitri Shostakovich

 

On the subject of burn in ..., posted on May 15, 2015 at 12:06:28
Feanor
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 It's been several years since my SDS-258 was new, but I don't recall that it need an extended period, perhaps 100 hour at most.

Like most amps it needs to be powered up for few minutes to sound its best. In the case of my 258, that's maybe 15 minutes, (vs. 45 minutes to an hour for my Pass Labs.)



Dmitri Shostakovich

 

RE: On the subject of burn in ..., posted on May 15, 2015 at 12:40:06
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 First, sorry I forgot to put you in the subject line!

"In the case of my 258, that's maybe 15 minutes"
I tend to agree. I notice that the 254 tends to come on with a brightness and flat sound-stage that seems stuck to an imaginary physical line between the speakers. After 10 to 20 minutes, it is like someone dials it into focus; voices suddenly sound like they are standing (at an appropriate distance, given the source) between the speakers, with a blossoming of the room acoustic that goes beyond the speakers.

Actually, the effect into the second day was very startling. I had the lights off and had been running the rig for a few minutes while watching a TV show (gotta love DVR!). After said show, we put on some vinyl ("Free Love", by Depeche Mode from their album, Exciter). The "scare factor" was that you could hear the backing vocals not only to the left and right of the lead, but also BEHIND the lead, lending to a very scary 3-D presentation! Nice.

Like I said, it doesn't sound pretty when first powered on, but if you play some music, after a few minutes, it will show it's true colors!

I'm still evaluating it, of course. I will be the first to admit that 3 or 4 hours of use is not enough time to give a concise opinion on this amp. It has changed its character so much in just this short amount of time. Considering (as I mentioned in my earlier post) I'm pretty impressed with what it does offer for the money! Let's see where things go from here...

Cheers,
Dman
Analog Junkie

 

RE: Paging "mwhouston"! IT'S ALIVE!!!! The Class D Audio SDS-254 LIVES!!!, posted on May 15, 2015 at 14:00:56
Mick Wolfe
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Posts: 3365
Location: AZ
Joined: October 10, 1999
Contributor
  Since: September 4, 2000
 Listening to my 254 as I type this. It's in my HT/casual set-up most of the time. Very listenable and I'm basically a tube guy.

 

Nice, posted on May 15, 2015 at 18:51:12
bullethead
 let is know how it sounds after 1,000 hours ;)

 

RE: Paging "mwhouston"! IT'S ALIVE!!!! The Class D Audio SDS-254 LIVES!!!, posted on May 15, 2015 at 21:11:29
Bill the K
Audiophile

Posts: 8385
Joined: June 3, 2006
 Good logic. I mean your logic, not the amp's design logic.

Cheers
Bill

 

So are we to surmise ..., posted on May 16, 2015 at 04:51:38
Feanor
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Posts: 9873
Location: London, Ontario
Joined: June 17, 2003
Contributor
  Since: March 12, 2004
 ... that you LIKE the top end "sound typical of class D amps"?

If not, you comment makes no sense.


Dmitri Shostakovich

 

Same and some important tips..., posted on May 16, 2015 at 06:44:17
Vinyl Valet
Audiophile

Posts: 1346
Location: Tempe, Arizona
Joined: November 13, 2003
 I'm assuming most of the posting owners are talking the stock kit.

Here's what I've done so far (254):

Hardwired quality power cord and speaker cable.

Installed high quality RCAs.

Here's the biggie; determine the correct gain for your system with the gain pots on the back, then measure and replace with high quality resistors on the board. Critical to get the most out of this puppy. I tried quality tube and TVC pres and preferred the TVC with the gain shorted (no need for expensive quality resistor) at the board. Since the heart of this system is a modded Oppo BDP-105, I want to try running that straight into the 254 and use Oppo's digital domain volume. Should be interesting.

Replace the stock 4700uf ps caps with higher quality 8200uf caps. If you don't have soldering experience, don't try this as the stock caps are difficult to de-solder and remove without messing up the ps board.

Sure, if you want to nit pick, you'll find some flaws compared to the super duper expensive stuff but for those that are looking for a sick amp for under $500, I doubt you could come close with anything else, especially with the relatively simple and cheap mods I've outlined above. Also there are guys that are more sensitive than most to the flaws of Class D stuff in general which I completely understand and respect. All amps have their flaws and we all have individual tastes and sensitivities.

Also keep in mind, when I make a positive comment about a component, I'm old, have bad rock & roll musician hearing loss in addition to pretty bad tinnitus. But my hearing is still solid in the critical midrange. My dad, before he passed, was deaf in one ear and probably was hearing 200Hz to 3kz in the other and he could still hear and appreciate the positives in my systems and insisted on similar quality in his home.

Most of the ideas listed above came from the generous contributions of several early adopters (link below). Since most of you aren't nutty enough to wade through something like 183 pages (sadly, I am), I've tried to condense the most important mods for you.
Open up your mind, in pours the trash. - Meat Puppets, 1987

 

RE: So are we to surmise ..., posted on May 16, 2015 at 06:57:35
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 Well, since I've never heard what the 'sound typical of class D" is, I wouldn't know. What I do know (as a bass guitarist of 29+ years) is what real instruments sound like. I know what live sound (both acoustic and amplified for better or worse) sounds like, and I know many musicians that play in all styles of music.

So until I am able to hear more Class D amps (not planning on buying more- I'm not a collector or swapper- so if anyone in the Wichita, KS area wants to compare...), I'm simply enjoying my perception of music as it is reproduced here at my home (with my respective gear, which I KNOW is different from just about everyone else's here).

While my jury is still out on a ruling, I am liking what I hear so far.

Cheers,
Dman
Analog Junkie

 

RE: Same and some important tips..., posted on May 16, 2015 at 08:32:17
Mick Wolfe
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Posts: 3365
Location: AZ
Joined: October 10, 1999
Contributor
  Since: September 4, 2000
 Thx for the tips. Well, I got to step one by replacing the stock powercord.

 

Class D amps don't all sound the same, furthermore ..., posted on May 16, 2015 at 08:40:08
Feanor
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Posts: 9873
Location: London, Ontario
Joined: June 17, 2003
Contributor
  Since: March 12, 2004
 ... and not despite that, in my limited experience they tend to sound less colored most.


Dmitri Shostakovich

 

A couple of upgrade options ..., posted on May 16, 2015 at 08:52:28
Feanor
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Posts: 9873
Location: London, Ontario
Joined: June 17, 2003
Contributor
  Since: March 12, 2004
 ... proved you case will accommodate them.

First, a Connexelectronic LPS220A power supply. They have 6x8200uF and 6x15000uF choices for +/-63 VDC output. I have the 6x8200uF in my DIY SDS-258 amp.

A second upgrade would be a RFI filtering IEC power cord receptacle.


Dmitri Shostakovich

 

RE: Nice, posted on May 16, 2015 at 09:01:12
Mick Wolfe
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Posts: 3365
Location: AZ
Joined: October 10, 1999
Contributor
  Since: September 4, 2000
 Whether it's my imagination or not, my 254 seemed to get much smoother/ listenable with age. Let's just say it seemed to improve quite nicely thru that 1000 hour threshold you mention. Doesn't mind a stable 4 ohm load either. Has been run almost exclusively with 4 ohm speakers in fact.

 

Thanks for bringin that up..., posted on May 16, 2015 at 09:04:58
Vinyl Valet
Audiophile

Posts: 1346
Location: Tempe, Arizona
Joined: November 13, 2003
 I forgot to mention, from the giant thread that I linked previously, the importance that most of the early adapters placed on a good power cord.

My view on most expensive power cords is that they are simply expensive and inefficient power line filters.

What I do and am doing (an evolving process) in all my systems is taking a good, relatively inexpensive bulk cord (DH Labs Encore or Power Plus depending on the application), hard wiring it to the component with a good power line filter design, customized for the current draw (most challenging for amps), again hardwired in line. I use ideas from The Felix Project (link below) as a basis for my designs. The only mechanical connection is a lower priced Wattgate male to the wall socket; again something cheap but good, like the old Acme silver plated & cryoed or more modern Porter Port (PorterHouse Audio). Of course, all the AC lines for my audio systems and my small recording studio are dedicated 10 gauge.

In the case of the Class D amps and their sensitivity to power cords, I believe that they are dumping some kind or crap back into the AC and undermining the operation of the other components rather than the amp's sensitivity to the crap on the AC line (haven't measured so this is just a guess). The reason I like my custom power cord with built in filter approach is that every component is isolated from the crap they want to spit out and the crap that's trying to make it's way in. Of course it's all hardwired both eliminating the degradation of any mechanical connection and the need for the silly expensive boutique connectors.

Yes, I'm cheap (all the time) and cheerful (most of the time). Have fun!
Open up your mind, in pours the trash. - Meat Puppets, 1987

 

Thank you. (nt), posted on May 16, 2015 at 09:48:17
Vinyl Valet
Audiophile

Posts: 1346
Location: Tempe, Arizona
Joined: November 13, 2003
 nt
Open up your mind, in pours the trash. - Meat Puppets, 1987

 

RE: do they make an integrated....., posted on May 17, 2015 at 08:32:11
wangmr
Audiophile

Posts: 2410
Location: Downtown
Joined: November 29, 2012
 their site does not seem to show one.

thanks for interest.

roger wang

 

RE: do they make an integrated....., posted on May 17, 2015 at 10:20:31
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 I don't think they do.

However, given that that input impedance isn't too bad (47k Ohms), one could simply add an input switch and relocate the input level controls to the front panel.

Wait! I might be onto something! I better inform Tom over there!

Dman
Analog Junkie

 

RE: Nice, posted on May 18, 2015 at 03:39:36
bullethead
 I find 1,000 hours good for all kinds of equipment, speakers included.

 

RE: Nice, posted on May 18, 2015 at 06:59:19
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 I've actually been noticing that the slight edge in the mid-treble (5 to 7 KHz) seems to be diminishing as I listened over the weekend. The detail I mentioned (especially in percussion instruments) has stayed, thankfully!

And this has been with maybe less than 10 hours on it so far. Since I may only average about an 60 to 90 minutes an evening (at least during the working week), I'll get back to you in roughly 2.73 to 3.65 years! LOL.

Most new gear I have heard tends to show their true colors within the first 100 hours, with some, but very minimal change after that. This includes tubes (power amps tend to "come on" quicker than tube pre's , IMHO) as well.

Enjoying this next leg of the journey, nonetheless. After all, isn't that what it really is about- enjoyment?
Dman
Analog Junkie

 

RE: Same and some important tips..., posted on May 18, 2015 at 08:08:02
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 Thanks for the link. Ironically, I have been following that thread for some time- it was one of the reasons I decided to pursue the Class D thing (in the first place, and with this particular amp), as well as the cost/performance ratio.

Regarding mods- My jury is still out on the RCA jacks. They seem solid enough and make a good, tight connection. Maybe later...

Power supply caps- even though the efficiency of this amp supposedly leans towards 90%, I still can't help feel that a total of 28,200uF isn't enough storage for the power rating, even if the amp isn't pushed to its limit... Maybe an upgrade to 40,800 total (6 x 6800uF) might make me sleep better at night!

I have been running my amp with the level controls wide open. this gives me the same amount of gain as my previous amps, and need to match subwoofer levels again (thankfully). I may remove the controls for the appropriate jumpers later, but for now, I'm gonna let the amp speak for itself...

What I DID find was that it was quite interesting to hear a difference with a change in AC power cords; I started with the standard 18AWG cord plugged from my surge protected power bar to the amp. This was upon the first time powering up. The sound was very harsh (even D-Wife noticed). Later, I plugged the amp right into the wall using a 14AWG cord- big difference (again, something D-Wife could also hear); more bottom end, better imaging, and less harshness. Of course, over the weekend, as I stated already, the harshness has begun to retreat.

Cheers, and thanks for the tips!
Dman
Analog Junkie

 

You're welcome. (nt), posted on May 18, 2015 at 08:28:06
Vinyl Valet
Audiophile

Posts: 1346
Location: Tempe, Arizona
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 nt
Open up your mind, in pours the trash. - Meat Puppets, 1987

 

RE: Nice, posted on May 18, 2015 at 12:01:02
Mick Wolfe
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Posts: 3365
Location: AZ
Joined: October 10, 1999
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  Since: September 4, 2000
 I'm home most days, so it's easy just to send Pandora 1 thru it for hours. Of course if you're not home, Pandora will shut down if you don't respond to "are you still listening" after a couple of hours. Since it's in my HT/casual set-up, movies get sent thru it as well. I wouldn't sweat it though, it just gradually sounds better with time with no strange hiccups or peaks/valleys along the way.

 

I think you might be right about that IEC..., posted on May 18, 2015 at 12:19:04
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 I was tempted by one other poster's thought on making the power cord captive, but you raise a good point about using an RFI filtered IEC as well!

Thanks for the tip!

Dman
Analog Junkie

 

RE: Nice, posted on May 18, 2015 at 12:24:12
Dman
Audiophile

Posts: 7211
Location: Kansas
Joined: January 28, 2001
 Well, that would all fine and dandy, but since D-Wife works from home, I don't think that she could tolerate having music on that for the whole day!

It's already starting to sound better, just over the weekend. I'm constantly being impressed with it's ability to convey some pretty wide dynamic swings, and the spotlighting on that sibilant range has been slowly disappearing as well.

Like I said, I'll keep everyone posted.
Dman
Analog Junkie

 

RE: do they make an integrated....., posted on May 22, 2015 at 07:51:03
wangmr
Audiophile

Posts: 2410
Location: Downtown
Joined: November 29, 2012
 hey, that'd be great if the designer could make it a minimal integrated.

thanks for any communication to the owner-designer.

roger wang

 

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