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  1. #1
    Ajani
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    Do you own a Class D Amp???

    I keep hearing a lot about how much Class D amps have improved over the years and according to some persons, they are as good (or even better) than traditional A/B amps now... So I'm just wondering how many forum posters own a Class D amp... And if you do, what it your opinion on their sound compared to more traditional alternatives?

  2. #2
    Silence of the spam Site Moderator Geoffcin's Avatar
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    Quote Originally Posted by Ajani
    I keep hearing a lot about how much Class D amps have improved over the years and according to some persons, they are as good (or even better) than traditional A/B amps now... So I'm just wondering how many forum posters own a Class D amp... And if you do, what it your opinion on their sound compared to more traditional alternatives?
    Yes, I've owned class D amps for years. I puchased a PS Audio HCA-2 to replace my old PS Audio 200c amp as soon as I read the review in Stereophile. It was everything they said about it and more. Right now it's doing duty in my HT rig as I'm having a fling with tubes at the moment, but I would still put it up there with some of the best amps money can buy for anywhere near it's price point. I would call the amp neutral, smooth, grainless, and just slightly loose compared to a lot of A/B SS amps in it's class. Certainly it doesn't have the "grip" of a Krell or Classe amp. T

    I also have a fun little "T" amp that I occasionally get to stun people with. While it can drive my maggies ( I gotta find that pic!), what's really fun is hooking it up to a couple of my more sensitive vintage speakers at a block party and get them rocking out. With music blaring at 90dB+ and no gear visable besided the speakers people start wonder what's driving them and I show them a palm sized amp connected to an Ipod nano!
    Audio;
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    PS Audio Classic 250. 500wpc into 4 ohms.
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    Marantz 6170 TT Shure M97e cart.
    Arcam Alpha 9 CD.- 24 bit dCS Ring DAC.
    Magnepan 3.6r speakers Oak/black,

  3. #3
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    My Linn amp is Class V according to them and I'm not sure how it differs from Class D but the end result is similar, an amp weighing in at 11 lbs that does, or rated, at 125x5. This is an older model and IMO does a great job. It can drive all five of my Dyn's in the HT set up to higher levels than I care to listen to and remain clean. Using the Primare preamp I thought the 5125 to be a bit bright but paired with the Marantz the highs are about right. I think the amp sounds very good. It also remains very cool even after running a couple movies.

    T+A on some amps use a digital power supply, not sure what Class they are supposed to be, these amps are excellent.

    I believe like tubes vs solid state, no matter the technology we just have to evaluate the amp on it's own merits. And as with my Linn it may also depend on other associated gear..
    Mark Levinson #512
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    Revel Performa F52 main/center & S30's
    SVS PC13 Ultra (sub)
    Marantz BD-7003 > AV-8003 > LINN 5125
    Transparent cables / Tributaries HDMI
    PS Audio Quintet

  4. #4
    Ajani
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    Thanks guys... I had not given Class D serious consideration before, since I was under the (wrong) impression that its real benefit was just efficiency, rather than good sound quality...

  5. #5
    Silence of the spam Site Moderator Geoffcin's Avatar
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    Quote Originally Posted by Ajani
    Thanks guys... I had not given Class D serious consideration before, since I was under the (wrong) impression that its real benefit was just efficiency, rather than good sound quality...
    There's at least two class D topologies; ICE developed by B&O (what my PS Audio uses), and Tripath who calls their tech a class "T" amp. Both have similar high power efficiency, and both sound great! I can tell you that even with my little $40 T amp the sound quality is remarkable.

    Audio;
    Ming Da MC34-AB 75wpc
    PS Audio Classic 250. 500wpc into 4 ohms.
    PS Audio 4.5 preamp,
    Marantz 6170 TT Shure M97e cart.
    Arcam Alpha 9 CD.- 24 bit dCS Ring DAC.
    Magnepan 3.6r speakers Oak/black,

  6. #6
    Super Moderator Site Moderator JohnMichael's Avatar
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    I own the Onkyo A-9555 integrated amp which is class D. The Onkyo received a positive review in Stereophile and a Class C rating. I do not think it was up to driving the Mo Fi OML 1's but I have not tried it yet with the Monitor Audio RS 6's. Very nice for an inexpensive integrated amp and better than the int. amp it replaced. The longer I listened the more I felt something was not quite natural.
    JohnMichael

    Vinyl Rega Planar 2, Incognito rewire, Deepgroove subplatter, ceramic bearing, Michell Technoweight, Rega 24V motor, TTPSU, Ringmat Anniversary mat, Michael Lim top and bottom braces, 2 Rega feet and one RDC cone, Benz MC Gold, GSP Fanfare 3 w/PSU1

    Digital Sony SCD-XA5400ES SACD/cd, Marantz SA 8001

    Int. Amp Krell S-300i

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  7. #7
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Ajani
    I keep hearing a lot about how much Class D amps have improved over the years and according to some persons, they are as good (or even better) than traditional A/B amps now... So I'm just wondering how many forum posters own a Class D amp... And if you do, what it your opinion on their sound compared to more traditional alternatives?
    I've owned three class D (or switching) amps:
    1. Panasonic SR-XA25 receiver. This is based on a Texas Instruments chip. This amp seemed to me to be quite bright for a long time but eventually burned in to a pretty decent sound -- after about 400 hours. I still have this amp currently powering a secondary, stereo HT system.
    2. Bel Canto eVo2i integrated amp. Based on a Tripath chip; (current Bel Cantos are ICEpower based). A very transparent, neutral, but some what "grey" or "bleached" sounding as you would say. I sold this to buy a pair of Monarchy SM-70 Pro amps which have a bit more tube-like "body", a warmer or at least slightly darker character.
    3. Class D Audio SDS-258. This is based on an International Rectifier chip. It's the amp I'm currently using. The sound is extremely transparent (like the Bel Canto or possibly even more so), and very neutral. Initially I thought the sound was a bit bright. However the impression of brightness has gone away after a couple of hundred hours, plus the use of the Magneplanar tweeter resistors to lower their about put by a decibel or so. I don't feel that it sounds "bleached", much less harsh or etched as some s/s amps can. Of the three amps the SDS-258 is the best to my ear. It has the best resolution and air and delivers instrument timbres with the best accuracy.
    Interesting perhaps ... When I replace the Bel Canto with the Monarchy, I felt the latter sounded better on about 70% of recordings -- however these were not the best recordings but rather those that had always sounded harsh or sharp. I was pretty happy with the Monarchys for over 2 years but I was aware I was missing something on the best albums. The Class-D-Audio SDS amps were cheap and I though by trying one it might clarify me what I was missing with the Monarchys. On the other hand I didn't expect too much given the low price.

    So now I have replace the Monarchys with the SDS-258. I now find the SDS is better than the Monarchys on 70% of albums -- but in this case they are the best recordings.
    Last edited by Feanor; 12-09-2010 at 07:04 PM.

  8. #8
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    I just posted a picture of my Sure TK2050 based Class D amp and Meanwell PS in my gallery. It's a near plug and play board amp which costs under $100 including the nice Meanwell PS. I've since changed the insides a bit and added better binding posts. Great sound for peanuts.

  9. #9
    Ajani
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    Quote Originally Posted by Poultrygeist
    I just posted a picture of my Sure TK2050 based Class D amp and Meanwell PS in my gallery. It's a near plug and play board amp which costs under $100 including the nice Meanwell PS. I've since changed the insides a bit and added better binding posts. Great sound for peanuts.
    I like the wooden box... I keep thinking that I could make a box for a class D amp that matches the Open Baffles I'm going to make...

  10. #10
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Poultrygeist
    I just posted a picture of my Sure TK2050 based Class D amp and Meanwell PS in my gallery. It's a near plug and play board amp which costs under $100 including the nice Meanwell PS. I've since changed the insides a bit and added better binding posts. Great sound for peanuts.
    Nice case! I like the plexiglass idea.

    Of course class D's don't put out nearly as much heat as other types. There's probably no significant risk, but I think some minimal ventilation on the top and bottom wouldn't be a bad idea just the same.

  11. #11
    Ajani
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    Feanor and Poultrygeist,

    Is there any serious risk involved in using a wooden box instead of a metal one??? I just need to know if there is a chance of.. oh... setting myself on fire or something like that...

  12. #12
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    Wood burns but doesn't conduct electricity. The Sure amp has a small fan atop the heat sinks that runs when the unit warms up. The Meanwell power supply has a fan as well. I also drilled 4 large holes in the case bottom next to the board for added ventilation ( you can see them in the other photo I just added to my gallery ).

  13. #13
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    Here's a very positive review of a CDA sibling of Bill's class D amp.


    http://www.affordableaudio.org/aa2010-08.pdf

  14. #14
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    Wooden case or metal - it's doesn't matter as these class D amps have floating grounds so grounding to the chassis is not necessary.

  15. #15
    Ajani
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    Quote Originally Posted by Poultrygeist
    Here's a very positive review of a CDA sibling of Bill's class D amp.


    http://www.affordableaudio.org/aa2010-08.pdf
    While I'd love Bill's own because it's balanced and supposed to sound better, but that one looks dead simple - just plug and play (zero soldering)... And I could always worry about building a case at a later date
    Last edited by Ajani; 12-18-2010 at 11:16 AM.

  16. #16
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Poultrygeist
    Here's a very positive review of a CDA sibling of Bill's class D amp.


    http://www.affordableaudio.org/aa2010-08.pdf
    I haven't heard the CDA, but I wouldn't call the SDS warm, rather it's neutral. However, if not warm, it definitely doesn't have the "etch" or grain that many s/s amp have.

    But apparently the CDA is like the SDA in having superb detail, i.e., resolution, which usualy translates into transparency and air. ("Detail" without transparency is really just etch, not real resolution.)

  17. #17
    Ajani
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    Hmmm... My fear of Feanor's model is the need to solder the XLRs... I wonder if I could just cut off the ends of one side of some cheap XLR cables I have and hook them directly to the circuit board (using the screw terminals) and connect the other end to my DAC output... Then I could get everything up and running without first having to build a pretty box (that could always happen at a later date)...

  18. #18
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    Haven't done XLR's but with each RCA's input one only has to solder the negative wire to the lag and the positive wire to the center pin which is the signal pin and is always positive. If you can plug in a soldering iron you can do it.

    If needed we can walk you through this.

  19. #19
    Ajani
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    Quote Originally Posted by Poultrygeist
    Haven't done XLR's but with each RCA's input one only has to solder the negative wire to the lag and the positive wire to the center pin which is the signal pin and is always positive. If you can plug in a soldering iron you can do it.

    If needed we can walk you through this.
    I'm sure soldering XLR or RCA isn't hard, but it would require me to buy a soldering gun and solder...

  20. #20
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Ajani
    Hmmm... My fear of Feanor's model is the need to solder the XLRs... I wonder if I could just cut off the ends of one side of some cheap XLR cables I have and hook them directly to the circuit board (using the screw terminals) and connect the other end to my DAC output... Then I could get everything up and running without first having to build a pretty box (that could always happen at a later date)...
    You could likely do that. XLR has three wires: +, -, and ground; of course you'd need be able to identfy each on the cut end of the cable. You'd need to cut off the male end of the cable, (the output end). (I know: sounds pretty gruesome!). You would need to be sure what wire was which polarity: to do that you might need a continuity checker to check between the remaining, female end and the ends of the three wires.

    Here's a pic of the ends of the XLR connectors:



    Or you could jus get yourself a soldering iron. Here's your best deal in that regard.


  21. #21
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    Instead of reading a book I've tackled the giant thread on Class D over at AC. Sounds like those who go with single ended inputs on the SD reap the same advantages as with XLR's. I'm not sure how that is but that's what I keep reading.

    One guy on AC prefers his MW with his horns over the CDA he built ( apples and oranges? ).

    What's stoked my interest is not only the flexibility and inexpensive slam of 120X2 into 8 ohms but the great fun of building it. I bet Feanor's would love to do another one. Right?

    Based on my gear specs Tom says I should go with the Super D 254.

    Feanor, how tall should my enclosure be to clear the tranny and could I easily get it all inside a 12"X12" case?

  22. #22
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Poultrygeist
    ....
    ... I bet Feanor's would love to do another one. Right?

    Based on my gear specs Tom says I should go with the Super D 254.

    Feanor, how tall should my enclosure be to clear the tranny and could I easily get it all inside a 12"X12" case?
    Yes, Mr Geist, I would like to build another.

    My case is internally 15.5 x 12 x 2.5". There isn't much room to spare on top of the transformer, so I'd look for 2.5" in height. 12 x 12" will be enough to get in the transformer and modules I'm pretty sure if you snug things together a bit more than I did ...


  23. #23
    Ajani
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    Perfect solution for either Feanor or Mr. Geist: Build an amp for me...

  24. #24
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    I've only done the much less complex Sure amp. Feanor's the man!

  25. #25
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Ajani
    Perfect solution for either Feanor or Mr. Geist: Build an amp for me...
    I might consider it ... email me if you're really, really interested and we can discuss details.

    Remember, though, that results would be more practical than elegant.

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