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| Model: | SDS-258 |
| Category: | Amplifier (SS) |
| Suggested Retail Price: | $360 for kit |
| Description: | Class 'D' stereo amplifier |
| Manufacturer URL: | Class D Audio |
| Model Picture: | View |
| Review by Feanor on August 15, 2010 at 13:23:22 IP Address: 216.99.101.100 | Add Your Review for the SDS-258 |
Let me premise my review by saying that I am poor, a cheapskate, and like classical music. Now let me begin with a conclusion: this component handily exceeds my expectations for an amp that cost me $450, furthermore it is highly competitive with amps I've owned costing 5x as much.
The SDS-258 amp description can be found HERE. This is a class 'D' amplifier based on a commercially available chip, however implementation is proprietary to Class D Audio (CDA); the amp is made in the USA. The amp and kit can be purchased only online direct from CDA.
The Kit. I constructed the case myself though CDA does offer a metal case as a separate option. Case construction was most of the work, follow by the wiring; the amp and power supply modules themselves are plug & play. Unfortunately at this time there is no user manual specific to the SDS models, however basic instructions were adequate for me who is certainly an electronics neophyte. HERE's a picture of my handy work; note that I opted for balanced XLR connectors since my preamp is balanced.
Associated Equipment. You see the rest of my system HERE, including my primarily reference, Monarchy SM-70 Pro amps. In recent years I have also owned the following amps, (latest to earliest): Bel Canto eVo2i (integrated); Adcom GFA-555II; NAD C270; Phase Linear 400.
Music for the review. For this review I relied mostly on classical music, especially large-scale choral music which offers, in my opinion, the best overall test of any component on account of its complexity. I did listen to orchestral and chamber works too, and some jazz.
RESULTS
Solid-state or class D "Nasties". Basically NONE! No grain, no etching, no glare, no dryness or "greyness". Personally I heard no "peculiar sounding highs" as some pundits have reported in case of class D, but I'll admit that I'm quite deaf above 10 kHz.
Hum & noise. No hum, no power-up or down transients, and no noise floor that I noticed.
Soundstage & imaging. Of course, these aspects are highly dependant on the recording, and this is where, IMO, quality, classical choral recordings are most revealing. I found that the SDS-258 delivers a very wide and reasonably deep soundstage; imaging was pin-point. However I'd say the SDS doesn't deliver the sort of artificial depth you get with tube equipment.
Transparency. Excellent! Not only exceeding anything I've heard near the price but also equalling or exceeding any of the aforementioned amps I've recently owned. By the the way transparency is not merely "detail": I equate transparency with "air", that is, the ability to separate instruments and voices from each other within the soundstage.
Tonal Balance ...
Bass. Solid and punchy as any of my mentioned reference amps; a bit more so than my current Monarchy SM-70 Pros, though probably the 2x-3x power helps in this regard. Perhaps the 50-100 Hz range is just a tad warm but just pleasingly so, (unlike the wooly NAD C270 for example).
Mid & Treble. CDA says its SDS amps have "beautiful smooth tube-like sound". Well it is free of the "nasties" mentioned above and I suppose tube-like as far as that goes, but if tube-like means "warm" to you, then you might be disappointed. Rather, in the mids and highs the SDS is quite neutral except for a narrow region of prominence in the lower treble. This is especially true versus the Monarchys which are a bit reticent or "polite" in that region, and also against the Adcom and the NAD. This prominence is slight but, to my ear, delivers a truer presentation of the harmonics of instruments including strings, brass, and percussion such as bell and cymbals. In fact, the SDS' reproduction of steel-brushed cymbals is the best that I heard -- no spray can "pssst" in this case.
On the subject of the true harmonics of instruments, I often feed that people who rarely listen classical strings think that they should always sound silky smooth -- well it isn't so! Depending on how and where they are played and, of course, how they are recorded, strings can sound quite strident. Brass too, and more obviously, can sound naturally strident. If a amp or any component unnaturally smoothes the natural stridency then it isn't delivering accurate reproduction. Whether the byproduct of its slight low treble prominence or for some other reason, the SDS-258 is as good or better at reproducing the full harmonic spectrum of instruments than any of my reference amps. But note I'm not saying that the SDS has the sort of "harmonic richness" attributed to a lot of tube equipment which is an artifact in my opinion.
I have always respected the Monarchys' sound but I now realize that it is really too polite in the upper midrange/lower treble. On the other hand the Monarchys are a forgiving amp versus the SDS-258. That is, depending on your associated equipment and taste, the SDS just might not be the right amp for you.
| Product Weakness: | There is a slight lower treble prominence which might make it problematic in combination up- or downstream components that have the same trait, or that are harsh or not well resolved. And Hey! this is a kit: you've got to find your own cabinet and wire in the modules. |
| Product Strengths: | A cheap, powerful, transparent, harmonically accurate amp to compete with amps costing several times its price. As a kit it is extremely easy to assemble. |
| Amplifier: | Class D Audio SDS-258 (under review) |
| Preamplifier (or None if Integrated): | Sonic Frontiers LINE 1 |
| Sources (CDP/Turntable): | Assemblage DAC 1.5 |
| Speakers: | Magneplanar MG 1.6QR |
| Cables/Interconnects: | Blue Jeans Cable |
| Music Used (Genre/Selections): | Mainly classical |
| Room Size (LxWxH): | 20 x 12 x 7.5 |
| Room Comments/Treatments: | n/a |
| Time Period/Length of Audition: | 6 hours |
| Other (Power Conditioner etc.): | n/a |
| Type of Audition/Review: | Product Owner |
| Your System (if other than home audition): | n/a |
Whilst doing amp "research", I read your review (above) of the Class D Audio SDS-258. I have the SDS-470 on my short list of SS amps and was going to ask if your comments still hold true on the 258 (as they are similar, just different power outputs), but your Inmate System page shows you have a Pass amp in there now. Did you give up on Class D in general?
Thanks,
Dman
Analog Junkie
I think criticism of class D tends to be a bit unfair. Although, of course, if you expect a class D amp to sound like tubes you will be disappointed.
Some critics, notably Morricab, make a point of criticising class D high frequency performance; he has call them "tizzy". But I don't agree: at worse they are a little bright although it very much depends on the recording. Let's say that class D amps (as well as some other s/s amps) don't cut much slack for bad recording practice.
My Pass Labs amp is better in every respect than the CDA SDS-258, although more in some respects than others. The thing to bear in mind is that the Pass X150.5 is 9x the price of the SDS-258. It's still my opinion that the Class D Audio amps are outstanding value for the money: perhaps NOTHING can touch them in this respect.
I love the music of Dmitri Shostakovich
I have not heard this DIY amp or any DIY amp but you should know immediately if an amplifier sounds realistic. All Class D amps I have so far auditioned I find totally unlistenable. Arcam Class G amps (made in US) are excellent but expensive 200 wpc P49 in UK £3K. I assume in the US price is only $3K ?
Edits: 03/02/15
I accept that class D isn't your preference -- although not all class D amps sound the same.
Meanwhile many class D amps have received excellent reviews from professional and amateur reviews; a recent example is the Stereophile review of the Theta Prometheus.
I love the music of Dmitri Shostakovich
I only comment on the Class D amps I have auditioned at Home as for audio magazines I do not believe any of their comments until I have heard the component for myself. I have been misled in the past by too many inaccurate reviews. I find the Stereophile comments on the Theta to be very dubious, why on earth pay $12K for 200 wpc when for approx a quarter of the price you can get the superb Arcam P49 200 wpc, unlike Class D you get first 5O watts in Class A without the excessive heat of all entirely Class A amps and antique tubes.
Edits: 03/02/15
My mention of the Theta Prometheus was only an example of class D, I wasn't saying you have to spend that much to get a decent class D amp.
The Arcam P49 might be a fine amp: I really don't know. Have YOU heard it?
"Sliding bias" systems have be around for a while going back to early Threshold models of the '70s. Another current example is the Cambridge Audio 'XD' models like the Azur 851W. The Arcam P49 and the Cambridge 851W might be quite fine but they are both north of two grand. Dman has a budget of $1000 he says.
I'm saying Class D Audio's SDS series sound great for the money. You can buy the fully assembled, encased SDS-470C with power supply upgrade for US$800. Or a full SDS-470 kit without case for $500: can't be beat!
I love the music of Dmitri Shostakovich
YES I have heard the Arcam A49 integrated amplifier which is why I am buying and expecting delivery tomorrow of the P49 stereo power amp. Look up Words & Music Andrew Everard and you will see the review of the A49. by Andrew Everard Gramophone,s audio editor. We both agree on the sound of the A49, however I totally disagreed with him on the sound of Sony TA-1ES amplifier.
I find it interesting when one can actually offer a VALID opinion based on their experience. While even that may vary (just like YMMV), it is good to ask someone about their thoughts.
I haven't made the "ultimate decision" yet, but the Class D Audio line up (and specifically, the SDS-470) keep popping back onto the list!
Thanks, and cheers,
Dman
Analog Junkie
After two weeks of listening to my SDS-258 my favorable impressions remain the same as my review.In important respects this amp is the best sounding that I've owned; (the others are mentioned in my review). (I did swap back to my Monarchys for serveral hours during this time interval.) The SDS-258 amp has amazing resolution, both apparent detail but, more significantly, "air" around the instruments. Bass is powerful and "quick". However what I love most is the authenticity, (truthfulness, verity, verisimilitude, or just plain accuracy), of instumental sounds. I'm convinced I'm hearing more the true harmonics especially of strings, brass, and percussion (including brushed cymbals), than I have ever heard before on my system.
What penalty this transparency and harmonic authenticity? Well I think some people will find this amp a little bright, at least the lower treble ... some might find it intolerably bright but that would be a matter of taste. Is this slight brightness related to the harmonic accuracy? Or is merely a minor fault? I'm not sure. However I do know that in live performance of classical music, instruments such as mentioned above, can frequently sound bright, strident, shrill, even glary. The performance venue is a big factor as is the music itself (obviously). So I for one expect that good recordings will accurately capture this stridency; further, I exect that good playback equipment will reproduce it. Those who don't just can't handle the truth, (or don't know it when they hear it).
___
My Stereo Configuration
Edits: 08/25/10
My experience with classdaudio amps - much to my surprise and deligh - are very similiar to yours.
Liquid, beautiful, sweet midrange and highs. Dynamics that are approaching live music experience, in both speed and range.
They in some ways sound much better than my multi thousand Musical Fidelity A1 2008, $1500 Quad 909, and my $3K Transcendent T8 OTL...
Really an incredible bargain.
Several buyers of the Class D kits gradually became aware of problems associated with their sonics after extended listening. You appear to have been listening to these amps since June. Anything emerging like that? Or do you still see it as a very high performing amp?
Hi,
I have not experienced any loss of enjoyment or noticed any particular deficiencies in the amp since I have put it in the system- I think it was actually July 4th weekend.
Having said that, I decided to bi-amp the DeCapos within about 6 weeks of powering up the classd. There was no particular reason for doing this besides that I just couldn't see letting my Transcendent OTL collect dust. After all it is sitting right there on the rack with the classd, and the DeCapos have connections for easy bi-amping.
So if there were some high frequency deficiencies that could become noticable over prolonged listening, I might very well be immune since I am biamping with the OTL.
As far as the mids and bass goes, no problems at all over time. Still am enjoying that lifelike dynamic speed, weighty and very tonally rich bass, and "present" but not 6 feet in front of the speakers midrange.
Sorry that probably doesn't help much...
regards,
kenzo
Feanor -
Nice work. I've been on the fence forever as to whether to take the the dive on Hypex modules, another implementation of Class D.
I like your case solution. What is your front panel made of? It looks to be stained or painted wood. Where did you get your rear panel? Did you fabricate it yourself?
Regards,
Karl
"'Cause when love is gone, there's always justice./And when justice is gone, there's always force./And when force is gone, there's always Mom. Hi Mom!" Laurie Anderson, "O Superman (For Massenet)"
Karl,The case top, bottom, and front are 1/2" MDF; the sides are 1x4 pine. The back is Hammond aluminum case cover , see item 1434-20 here , which I bought from Parts ConneXion.
This was a cheap but not great case solution. The 1/2" MDF is too thick to easily cut out for controls, e.g. the on/off switch on the front. It's also too thick for drilling to mount the PC boards. I struggled without one, but I'd recommend a set of Forstner drill bits to create thinner spots in the MDF where you need to insert bolts or fit a control.
The Hammond aluminum panel, (1434-20), is a bit thin on the other hand. I recommend a "step drill" for drilling circular holes in the aluminum. I fitted the IEC AC input by drilling a circular hole, then used a file to complete the fitting -- this pretty tedious.
___
My Stereo Configuration
Edits: 08/19/10
Here is a pic of the same amplifier that I built. My experience with the amps performance is the same as Feanor's review. Great amp! Les Hudson
Transformer-on-top look is "different".
Thanks for commenting.
___
My Stereo Configuration
for those of us also poor and looking for quality sound at a budget price.
Recently going through the misery and heartbreak associated with a broken amp
I was looking into Class D amplification but didn't find anything appropriate at this
time.
Based on your review though and also being an electronics neophyte, this kit looks like
a good bet for a not-too-far-in-the-future-project.
Well done! Thanks!
" Once this was all Black Plasma and Imagination." -Michael McClure
Oh no! did your ST-70 take a dive? Hope not - looks really cool (and I bet sounds great).
Thanks, not a big deal to get it repaired (I shouldn't have said I am poor - I doubt anyone posting on an audiophile website is actually poor)
but I don't want/need the hassle and expense right now. I bought a used Adcom GFA 454ii to tide me over for a while and investigate the SS
amp/tube pre combo for a while.
So far I love it - though a different and engaging beast it is.
So, Feanor's Class D review is right on time and sounds like the type of direction I'd like to move in by 2011.
Your linked info is also helpful in this regard.
Gracias!
" Once this was all Black Plasma and Imagination." -Michael McClure
I agree with all your points. Posters here are likely are not poor in the literal sense. I sometimes feel that way reading other forums, when guys talk about upgrading their McIntosh MC501 monoblocks to MC1201s like the money is almost pocket change ...! and it likely *is* to them.
I borrowed an Acurus A150 and liked what I heard; cool to get an SDS kit sometime in the future as an alternate to my 8W 300B amps; sounds like it's a "contender" for a reasonably priced SS amp with excellent sonics.
I do have several "projects" on the list tho! and have to choose if/when I can get what ...
~$200 (Boxee Box, releasing in ~November; Nordost Magus power cord(s) for McIntosh C220, Cambridge 840C)
~$500 (ERGO Room corrector)
~$700 (SDS amp in their 'custom enclosure' as I am not a 'casework' guy, plus good switches and connectors)
~$1500 (used Ref. 3A MM deCapo i speakers)
and it goes up from there ...! I am afraid anything beyond the $500 range will have to wait until I get a (substantial) raise or bonus.
Oh well, such is life ...! I feel privileged to even be able to think about spending > $200 on a hobby.
nt
Does that mean you spent every last spare dime on speaker (components, material for enclosures, etc.) ???!!! Looks like it! Nice looking stuff you have/made there!
I have paid for an education.
I hadn't heard of that before, but I do believe digital room correction is going to be big in the future.
___
My Stereo Configuration
Yes, this is available for $500 (plus adapters from 1/4" to RCA or balanced connectors). It works 'only' from 500Hz on down, and has the Lyngdorf Room Correction algorithms.One main thing I like is it uses 24/96 ADCs and DACs, so should be pretty 'transparent'. Does it 'truncate' the soundstage depth? That's one of my concerns. I am hoping it's effect is to 'enlarge' the soundstage, and maybe this 'good' effect will overcome any 'bad' effects the process has.
Does it do everything the full blown (and full-spectrum) Lyngdorf or McIntosh version does? Don't know, don't really worry as I can't afford those!!!
I KNOW I have some modes at (maybe 25), 50, 100, and 200 Hz ... I think this thing can EQ them 'out' pretty well, and want to try it. I cannot get away with acoustic treatment (esp. what would be needed to suppress 25 and 50 Hz energy!).
I listen in the nearfield to stand-mounted monitors, that are well away from the walls (and have a powered sub). I am hopeful this thing will 'treat' the room as well as a total acoustic panel/trap system would.
The DSP based EQ includes PHASE correction, so I think it actually works much better than a 'regular' EQ, and can actually "act" like absorbers/traps would. At least that's what I am telling myself ...!
It's worth $500 to me to experiment with it.
Edits: 08/17/10
... but THAT ain't going to happen for me either!
___
My Stereo Configuration
I have two of Tom's CDA-224s running bridged as mono blocs, and my opinion of their sound is right in line with yours. I'm using a tube preamp and have found, as have others, that this is a very good combination. I sold my tube mono blocs after buying these and have found my Magnepans (MG12s) have never sounded better.
Bob
Wow! Feanor, thanks for the review! I recently borrowed an Acurus A150 amp from a friend to compare with my Bottlehead Paramount 300B amps, and was pleasantly surprised by the results. Certainly I heard the A150 as flatter in response and liked what I heard overall.
I did know about the SDS amps from other threads (see link), and also the Monarchy amps seemed like a good alternate for "low-cost" amps that punch way above their price range.
Good to have choices like these when one is a 'poor' audiophile!
Interesting. There was and is a lot of stuff going around about how class D doesn't have natural extended highs -- I just don't know; I'm basically totally deaf above 10 kHz. However what I do know is that this SDS-258 is significantly more accurate and natural sounding than the Monarchys, the Adcom, and the NAD. The other class D, I've owned, the Bel Canto, was closer but I think the CDA is better.The likes of Pass Labs, ARC Reference, Atma-Sphere, VTL, or Spectron, etc., might do wonderful things but I won't be getting any of them any at time soon. Good low-cost equipment is where it's at for me.
On the broader s/s vs. value controversy, my position has been that lot of people like latter because they are willing to trade accuracy for euphonics. (Is accuracy "ying" and euphonics "yang" or vice versa??)
___
My Stereo Configuration
Edits: 08/16/10
I wonder how the TI module amps they have sound compared to the CDA and SDS amps? ay-yi-yiiii ... too many choices !!! :^)
What's BTL & PBTL ??? oh well, that's for the TI amp only, guess I shouldn't worry about it ...
BTW, and what's the diff between the CDA and SDS? I see the SDS can accept balanced inputs ... aha, I guess that IS the difference (and the SDS series is 'newer'). I certainly would want the SDS ...
Too many toys, too little money ... :^D
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