Hi Eric,
many thanks for kind review.
I'll planing similar setup to compare. Currently i drive my Dynuadio Focus 360 by Denon 4400 (Class AB), but i will put out feelers to Class A (F5 double version, boards and IRFs already received) and to Class D (SDS-254 already ordered and on transit).
I'll look foward to receive the SDS Parcel
Regards
Marcus
many thanks for kind review.
I'll planing similar setup to compare. Currently i drive my Dynuadio Focus 360 by Denon 4400 (Class AB), but i will put out feelers to Class A (F5 double version, boards and IRFs already received) and to Class D (SDS-254 already ordered and on transit).
I'll look foward to receive the SDS Parcel
Regards
Marcus
Pass DIY Addict
Joined 2000
Paid Member
John: I was wondering if you were still watching this thread - good to hear from you. My apologies - I feel as though I've highjacked your thread and taken it a little bit off topic. I am impressed by the CDA-254, though I just wonder if Class-D audio as a topology needs more time to mature and be refined through advances in technology. Cheers to ClassDAudio, Hypex, and others for moving this forward!
Marcus: I am very interested to hear your impressions of the SDS-254! I looked at this model as well before I made my purchase - primarily for the balanced inputs. My guess is that the CDA-254 is probably 85-90% comparable to the SDS version and for my purposes (surround speaker array), the CDA does a great job! Thus, I opted for the lower priced version. It's very tempting to go and pick up another few amps (such as the Hypex that John originally inquired about) to do some comparisons, but I think my amplifier building is finished for the near-term future. It's time to spend some time enjoying rather than building for a change... <flame suit on> ;-)
Marcus: I am very interested to hear your impressions of the SDS-254! I looked at this model as well before I made my purchase - primarily for the balanced inputs. My guess is that the CDA-254 is probably 85-90% comparable to the SDS version and for my purposes (surround speaker array), the CDA does a great job! Thus, I opted for the lower priced version. It's very tempting to go and pick up another few amps (such as the Hypex that John originally inquired about) to do some comparisons, but I think my amplifier building is finished for the near-term future. It's time to spend some time enjoying rather than building for a change... <flame suit on> ;-)
Since I listen primarily to classical (being a retire NPR Station Manager and program producer) I value soundstage replication above all else. I find that to be the most difficult parameter to "get right" and for me accounts for most of the differences among amps and dacs. Now that I have found speakers that "do it right" (Paradigm Sig1v3s) I have become very picky on ancillary gear. I listened to planars for years but have deciced in my declining years that point source mini-monitors do a better job at sounstaging, provided they have sufficiently low distortion and sufficiently high power handling. The Sig1s do all of the above. Thanks for all the input. Regards
Pass DIY Addict
Joined 2000
Paid Member
OK, I have an update that I have to admit I'm a bit embarrassed to make. I was having a problem reconciling all of the great reviews I've found about the ClassDAudio amps and my own listening experience (reflected in my long post above). Yes, these amps sound very nice, but to me, they just didn't live up to what everyone else is saying about them.
Well, I found the problem - I had inadvertently reversed the speaker Pos and Neg terminals for one of the channels inside the amp when I assembled it. Doh! Rookie mistake, I know. I thought I was being careful during assembly, but somehow I missed this detail. It only affected a single channel, but it happened to be the channel I used during my earlier listening evaluation - go figure!
So fast forward a bit. I corrected the phase issue with the amp and moved things around again so the ClassDAudio amp was driving my Avro speakers. I cued up the Mark Knopfler disk again to have a listen (just as before). I was stunned by what I heard! Imaging was there in spades. The soundstage was comprehensive from left to right. The treble was still just a bit edgy for me, but was noticeably improved from my first experience. In contrast with my earlier listening experience, I was no longer able to identify the specific location of the actual speakers. With one or two tracks, I actually had to touch the drivers in my center channel to make sure my preamp was really operating in stereo mode.
I didn't notice much of a difference in the bass, but it had been strong before. This amp is still not happy pushing the Avros up to the 100dB mark, but I'm impressed by what it can do with these power hungry speakers.
There is still a clear difference between the ClassDAudio amps and my DIY Pass clones (the Pass clones have smoother treble, more midrange bloom and presence, and stronger bass), but the gap is clearly more narrow than I conveyed with my initial impressions.
I was pleased with the sound of the ClassDAudio amp before, but after fixing my construction error, I have to say this amp sounds ridiculously good! If there is an award for bang-for-the-buck, the CDA-254 is a clear contender!
Well, I found the problem - I had inadvertently reversed the speaker Pos and Neg terminals for one of the channels inside the amp when I assembled it. Doh! Rookie mistake, I know. I thought I was being careful during assembly, but somehow I missed this detail. It only affected a single channel, but it happened to be the channel I used during my earlier listening evaluation - go figure!
So fast forward a bit. I corrected the phase issue with the amp and moved things around again so the ClassDAudio amp was driving my Avro speakers. I cued up the Mark Knopfler disk again to have a listen (just as before). I was stunned by what I heard! Imaging was there in spades. The soundstage was comprehensive from left to right. The treble was still just a bit edgy for me, but was noticeably improved from my first experience. In contrast with my earlier listening experience, I was no longer able to identify the specific location of the actual speakers. With one or two tracks, I actually had to touch the drivers in my center channel to make sure my preamp was really operating in stereo mode.
I didn't notice much of a difference in the bass, but it had been strong before. This amp is still not happy pushing the Avros up to the 100dB mark, but I'm impressed by what it can do with these power hungry speakers.
There is still a clear difference between the ClassDAudio amps and my DIY Pass clones (the Pass clones have smoother treble, more midrange bloom and presence, and stronger bass), but the gap is clearly more narrow than I conveyed with my initial impressions.
I was pleased with the sound of the ClassDAudio amp before, but after fixing my construction error, I have to say this amp sounds ridiculously good! If there is an award for bang-for-the-buck, the CDA-254 is a clear contender!
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No
The answer after 24 posts is no. Apparently no one who owns a UcD finds any value in comparing to amps whose manufacturer descended from a deceitful brand. Remember the former "classdaudio" which *never* sold a Class D circuit? Yet because the forum moderator had no integrity, he allowed trash to pollute and wreck a once-respected, *actual* class D forum.
The new classdaudio company's designs look fine for cheap DIY amps. They don't bother to post a datasheet, not even IMD numbers, so one shouldn't expect the stellar performance that UcD achieves. Hence the comparison is rather silly, IMO.
The answer after 24 posts is no. Apparently no one who owns a UcD finds any value in comparing to amps whose manufacturer descended from a deceitful brand. Remember the former "classdaudio" which *never* sold a Class D circuit? Yet because the forum moderator had no integrity, he allowed trash to pollute and wreck a once-respected, *actual* class D forum.
The new classdaudio company's designs look fine for cheap DIY amps. They don't bother to post a datasheet, not even IMD numbers, so one shouldn't expect the stellar performance that UcD achieves. Hence the comparison is rather silly, IMO.
I have been unfair, the culprit was and is the Class_D Ltd. company. Under several names, still standing, that gave the general name a bad rap. It's shadow obscured an apparently solid company, Class D Audio. It appears that the solid company will outlast the culprit, so there is hope for mankind!
No, haven't tried the Cass D Audio modules yet, but they measure well at the price point and do have good manuals. The earlier debacle can be viewed here:
http://www.diyaudio.com/forums/class-d/141588-mini-review-class-d-designs-nx200-vs-hypex-2.html
I have a pair of Bel Canto S300s, very nice amps, green as can be. I would like to hear some Hypex UcD or nCore amps someday, but my current system has more pressing weaknesses at the moment.
I got a response on Class D Audio from Earflappin, he pointed me below.
Given the competition and relative price, he thought the Class D Audio amps were excellent. My apologies to all!
See:
http://www.diyaudio.com/forums/vendors-bazaar/190434-hypex-ncore-41.html#post2901063
"I have been a die-hard Class A amp guy – SS and tubes including OTL’s - for decades. I tried a Halcro when they first came out. It may have boasted ultra-low distortion figures, but it was too sterile and thin sounding for my tastes. If this meant I liked an amp with coloration then so be it. Bring on the color.
A few months ago I bought a Class D Audio SDS kit just for kicks based on a friend’s recommendation. Compared to my Class A OTL’s they had better bass articulation, similar midrange, better macro/micro detail, but overall the tonal and energy balance wasn’t right. They sounded “over-caffeinated” and had a glassy, un-natural sounding high frequency, which quickly led to listener fatigue. The amp over exaggerated leading edge transients and truncated the decay. Despite these negatives, I found myself enjoying the SDS for periods of time, but ultimately preferring my Class A OTL’s for their better tonal balance and natural sound.
Within just a few seconds of listening to the nCore I knew they were a game changer. This is the most accurate, resolving yet musical amplifier I’ve heard with perhaps the exception of the Clayton M300’s. I can’t be definitive on the Clayton’s as I heard those at a friend’s place who has a system very similar to mine and it’s been too long to rely on aural memory. I will be sending him my nCores so he can weigh in with his own impressions..."
No, haven't tried the Cass D Audio modules yet, but they measure well at the price point and do have good manuals. The earlier debacle can be viewed here:
http://www.diyaudio.com/forums/class-d/141588-mini-review-class-d-designs-nx200-vs-hypex-2.html
I have a pair of Bel Canto S300s, very nice amps, green as can be. I would like to hear some Hypex UcD or nCore amps someday, but my current system has more pressing weaknesses at the moment.
I got a response on Class D Audio from Earflappin, he pointed me below.
Given the competition and relative price, he thought the Class D Audio amps were excellent. My apologies to all!
See:
http://www.diyaudio.com/forums/vendors-bazaar/190434-hypex-ncore-41.html#post2901063
"I have been a die-hard Class A amp guy – SS and tubes including OTL’s - for decades. I tried a Halcro when they first came out. It may have boasted ultra-low distortion figures, but it was too sterile and thin sounding for my tastes. If this meant I liked an amp with coloration then so be it. Bring on the color.
A few months ago I bought a Class D Audio SDS kit just for kicks based on a friend’s recommendation. Compared to my Class A OTL’s they had better bass articulation, similar midrange, better macro/micro detail, but overall the tonal and energy balance wasn’t right. They sounded “over-caffeinated” and had a glassy, un-natural sounding high frequency, which quickly led to listener fatigue. The amp over exaggerated leading edge transients and truncated the decay. Despite these negatives, I found myself enjoying the SDS for periods of time, but ultimately preferring my Class A OTL’s for their better tonal balance and natural sound.
Within just a few seconds of listening to the nCore I knew they were a game changer. This is the most accurate, resolving yet musical amplifier I’ve heard with perhaps the exception of the Clayton M300’s. I can’t be definitive on the Clayton’s as I heard those at a friend’s place who has a system very similar to mine and it’s been too long to rely on aural memory. I will be sending him my nCores so he can weigh in with his own impressions..."
Sorry but the 'overcaffeinated' 'glassy' high frequency on the SDS does not sound right, as the classdaudio amps in general are reported to sound the opposite - warm, smooth, and even slightly rolled off at the the top depending on speaker impedance. Listener fatigue in particular is rare from what I've read (and heard). Many replace them with their high-priced tube amps. However, I do think they are more finicky when it comes to component matching, particular the CDA series. Every now and again someone reports dissatisfaction with them but they vary - sometimes it's the highs, sometimes it's the mids, or something else. I say this because I've followed feedback on these amps since they came out and though issues have come up, high end fatigue is uncommon. It's too bad that these amps/irs2092-based amps get dismissed with the usual class d/t memes.
It's also possible some element of the amp design was changed. Unfortunately, Classdaudio does not make much effort to inform about changes that are made to the boards or even new product additions, which does not help matters. Now china-based irs2092 amp makers are making inroads here on diyaudio 2 years after classdaudio debut here with the same design to little notice.
It's also possible some element of the amp design was changed. Unfortunately, Classdaudio does not make much effort to inform about changes that are made to the boards or even new product additions, which does not help matters. Now china-based irs2092 amp makers are making inroads here on diyaudio 2 years after classdaudio debut here with the same design to little notice.
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And they're not getting a lot of notice either, which I just don't understand. They're less inexpensive, for a channel of flawless amplifier, than a single foil inductor. To use anything else for woofers or mids is simply to throw your money away . . . nothing sounds better. You'd be hard put to find anything that sounds better for tweeters either, but the lower power requirements of most tweeters means that a good chip amp will perform as well (which is why I haven't replaced mine).
But spending thousands, or even just hundreds, of dollars for amplifiers is now money down the drain.
QFT.
These amps are good, affordable designs. A friend built them.
I prefer the latest generation ICEpowers tbh and even a properly built Tripath amp is more exciting (even if it measures horribly).
Hypex are The State of The Art in Class D, so a comparison is not really interesting. They're in a different league.
I finally got around to building a test mule of that SDS-224 with parts from the spare pile: 1000 watt 25 VAC Plitron, 6 CDE 11,000 uF caps, generic bridge and some quality connectors stuffed into a scavanged SCA generator chassis.
Observations:
Manufacturer support - wrong instructions, no response to follow up requests. Needs work, lots of work.
Grounding - A real bear. Buzz and hum galore driven balanced by a Benchmark DAC 1. I've linked cheap studio gear over 200' of multi pair CAT3 with nowhere near the hassle. The eventual, and only, solution was using isolated standoffs and hard-grounding the PCB to chassis right at the audio input.
Idle tone - Still there, 1.4 volts p-p @ ~ 400 kHz, and still not happy about it.
Sound - This is the first extended listen to solid state amps at home in over 20 years, discounting an ancient $75 Rotel integrated used during a cross country move. At work I hear Brytons, Mackies, Genelecs regularly though. I could quiblle over its ability to resolve detail at the very lowest level but beyond that, on Apogee Centaur Minors, it needs no apologies. Bass is particularly amazing in a way that makes no sense from a numbers perspective. Imaging on studio gimmickry is pinpoint and huge on minimally mic'd acoustic recordings. This thing's worth every penny.
Observations:
Manufacturer support - wrong instructions, no response to follow up requests. Needs work, lots of work.
Grounding - A real bear. Buzz and hum galore driven balanced by a Benchmark DAC 1. I've linked cheap studio gear over 200' of multi pair CAT3 with nowhere near the hassle. The eventual, and only, solution was using isolated standoffs and hard-grounding the PCB to chassis right at the audio input.
Idle tone - Still there, 1.4 volts p-p @ ~ 400 kHz, and still not happy about it.
Sound - This is the first extended listen to solid state amps at home in over 20 years, discounting an ancient $75 Rotel integrated used during a cross country move. At work I hear Brytons, Mackies, Genelecs regularly though. I could quiblle over its ability to resolve detail at the very lowest level but beyond that, on Apogee Centaur Minors, it needs no apologies. Bass is particularly amazing in a way that makes no sense from a numbers perspective. Imaging on studio gimmickry is pinpoint and huge on minimally mic'd acoustic recordings. This thing's worth every penny.
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Pass DIY Addict
Joined 2000
Paid Member
Marcus,
Any updates on your amp building? I'm curious to hear your reactions and the specific comparisons that you indicated above...
Darn all of these life obligations that get in the way of amp building and listening
Eric
Marcus,
Any updates on your amp building? I'm curious to hear your reactions and the specific comparisons that you indicated above...
Darn all of these life obligations that get in the way of amp building and listening
Eric
Marcus,
Any updates on your amp building? I'm curious to hear your reactions and the specific comparisons that you indicated above...
Darn all of these life obligations that get in the way of amp building and listening
Eric
Hi Eric,
sorry for being late
I had build up the SDS254 breadboard and it sounds realy great, better than my Denon 4400, since the SDS runs the Denons diconnected and put in mothballs
I decided to order second board and run both in mono bridged mode, also little imrpovment of sound stage.. i guess one board would drive my speakers well also, but it seems i need the glow of more electronic compared to the speakers
Than i began to tweak the SDS254 a little bit, really and clear improvment possible by replace some Power Supply, Filter and Couple Capacitors (refere attached picture and found replaced SMD tantal caps by normal Panasonic and Elna Types
) ..The amps sounds now fantastic, smooth, very musical, rich in detail and tight bass.
Never again think about to build pass amp, i love class D stuff !
Regards
Marcus
Attachments
Pass DIY Addict
Joined 2000
Paid Member
Improvement od classdaudio SDS470
I work on the improvement of the sound for many months,my SDS470 (bought complete) is directly connected to a Weiss DAC2 (without preamp)and shortly connected to 2XDuntech prince speakers.
Today, i can say that the sound is the best ever obtained at home,...as good as with a Devialet D Premier(costing usd15000), recently tested in comparison with its owner,even better than my former amps =Airtight ATM2,AR Classic60,AYON TritonII.
This amp is absolutely incredible!!but rather difficult to optimize,since the balance (between low,medium and high frequencies) is not perfect when connected for the first time therefore improvements are not yet applied.
In particular, the high frequencies are rather shy, and the high-low can be slightly proeminent consequently masking the remainder. Moreover a glassy tendency may exist,coming from some excess of medium between 1 and 2k,glassy sound which disappears when such excess is reasonably damped.
This amp is so transparent that as a counterpart it is extremely sensitive to any mod, in particular to=
-main power supply cable,main PS cable of the dac (and polarities amp/dac))
-interconnect between dac and amp
-type of speaker cables
- rather bad or medium quality digital source(CD drive fr example),which may produce some intermodulation gremlins (a reduction of jitter before entering the dac is a must...)
About speaker cables, i suggest that you try bi-wiring as follows=:
.Flat cable (solid) high section (2to6mm2)for the Ground,common ground for lows and highs
.Litz wire 8X0.28MM (+)25X0.05mm for the (+) highs
.1 to 3(number to be chosen)X AWG24 silver plated wrapping wire for the (+) lows
minimum length (less than 2m)
About the interconnect=UNSHIELDED,made in litz wire or buy a VOVOX DIRECT S (XLR Balanced)
About the PS mains cable=DIY 4 brands of each 8X0,28mm litz wire,braided 2 clockwise, 2 counterCW.In all cases,avoid big sections of main cable!
About the mods inside the amp=remove the RCA sockets (keep only XLR),put the pots in the holes of the RCA's and shorten the pots wires to about 4cm,replace the speaker wires by cables similar to the a.m.ones.(takes 30')
Yull see drastic improvements,then yu can optimize in function of yur system.
NOTA=i bought a spare PS board equipped with Panasonic 10kmF low resistance capacitors, but the sound is so perfect that i hesitate to test the new PS board.
I work on the improvement of the sound for many months,my SDS470 (bought complete) is directly connected to a Weiss DAC2 (without preamp)and shortly connected to 2XDuntech prince speakers.
Today, i can say that the sound is the best ever obtained at home,...as good as with a Devialet D Premier(costing usd15000), recently tested in comparison with its owner,even better than my former amps =Airtight ATM2,AR Classic60,AYON TritonII.
This amp is absolutely incredible!!but rather difficult to optimize,since the balance (between low,medium and high frequencies) is not perfect when connected for the first time therefore improvements are not yet applied.
In particular, the high frequencies are rather shy, and the high-low can be slightly proeminent consequently masking the remainder. Moreover a glassy tendency may exist,coming from some excess of medium between 1 and 2k,glassy sound which disappears when such excess is reasonably damped.
This amp is so transparent that as a counterpart it is extremely sensitive to any mod, in particular to=
-main power supply cable,main PS cable of the dac (and polarities amp/dac))
-interconnect between dac and amp
-type of speaker cables
- rather bad or medium quality digital source(CD drive fr example),which may produce some intermodulation gremlins (a reduction of jitter before entering the dac is a must...)
About speaker cables, i suggest that you try bi-wiring as follows=:
.Flat cable (solid) high section (2to6mm2)for the Ground,common ground for lows and highs
.Litz wire 8X0.28MM (+)25X0.05mm for the (+) highs
.1 to 3(number to be chosen)X AWG24 silver plated wrapping wire for the (+) lows
minimum length (less than 2m)
About the interconnect=UNSHIELDED,made in litz wire or buy a VOVOX DIRECT S (XLR Balanced)
About the PS mains cable=DIY 4 brands of each 8X0,28mm litz wire,braided 2 clockwise, 2 counterCW.In all cases,avoid big sections of main cable!
About the mods inside the amp=remove the RCA sockets (keep only XLR),put the pots in the holes of the RCA's and shorten the pots wires to about 4cm,replace the speaker wires by cables similar to the a.m.ones.(takes 30')
Yull see drastic improvements,then yu can optimize in function of yur system.
NOTA=i bought a spare PS board equipped with Panasonic 10kmF low resistance capacitors, but the sound is so perfect that i hesitate to test the new PS board.
power supply for sds
Hi Marcus,
I have an sds 470 and considering improving power supply and other caps. I looked at your picture and see you have added quite a lot of capacitance. Can you share a little more information about the values of capacitors you are using. Also on my amp board I have 4 x 560 uF 100v caps. Not so easy to find high quality replacements for these. Did you come across these on your amplifier board.
Thanks
Hi Eric,
sorry for being late
I had build up the SDS254 breadboard and it sounds realy great, better than my Denon 4400, since the SDS runs the Denons diconnected and put in mothballs
I decided to order second board and run both in mono bridged mode, also little imrpovment of sound stage.. i guess one board would drive my speakers well also, but it seems i need the glow of more electronic compared to the speakers
Than i began to tweak the SDS254 a little bit, really and clear improvment possible by replace some Power Supply, Filter and Couple Capacitors (refere attached picture and found replaced SMD tantal caps by normal Panasonic and Elna Types
The amps sounds now fantastic, smooth, very musical, rich in detail and tight bass.
Never again think about to build pass amp, i love class D stuff !
Regards
Marcus
Hi Marcus,
I have an sds 470 and considering improving power supply and other caps. I looked at your picture and see you have added quite a lot of capacitance. Can you share a little more information about the values of capacitors you are using. Also on my amp board I have 4 x 560 uF 100v caps. Not so easy to find high quality replacements for these. Did you come across these on your amplifier board.
Thanks
Pass DIY Addict
Joined 2000
Paid Member
Wow, Martin! That is a ton of caps! Glad to hear that you like it so much. I really enjoyed mine, but I gave up on it last year after my local power utility switched from using human meter readers to TWACS (two way automated communication system). The twacs system works by sending a 400hz carrier wave through the power grid that made my class-d amp buzz like crazy when it occurred (roughly every hour or so). The buzz went right through to the speakers each and every time!
I never figured out a way to prevent the noise bleed through. I tried everything: an isolation balanced power transformer, more caps, emi filters, thermistors... I ran out of ideas before I could solve the problem, so the Class-D amp got replaced by a set of MA-500 monoblocks from Marantz for now.
I never figured out a way to prevent the noise bleed through. I tried everything: an isolation balanced power transformer, more caps, emi filters, thermistors... I ran out of ideas before I could solve the problem, so the Class-D amp got replaced by a set of MA-500 monoblocks from Marantz for now.
the beauty of those sds amp is you can set the gain with a fix resistor, so on my open baffle horn full range i may need 10 watt out of 200 + watts of my sds258.
so each channel is tame with a 47k Ohm resistor which send the noise floor into oblivion with a tube balanced preamp...
Martin Gagnon
so each channel is tame with a 47k Ohm resistor which send the noise floor into oblivion with a tube balanced preamp...
Martin Gagnon
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