Class D Amp

I just purchased a used Class D Audio amp, the CDA-254S for $160.
Class D Audio CDA-254S Kit - Class D Audio Kits - PRODUCTS

Its in a wooden case but I am going to put it in this chassis-

Par-Metal

I'm giving it to my son to pair with his Maverick tube DAC/Preamp and his PSB B6's.

I'll give a review after we have had it for a few days.

Nothing wrong with using a wooden case and you'll run into fewer grounding issues. I used a plexi-glass cover with my Sure amp and have since drilled holes over the fan.

http://://gallery.audioreview.com/da...m/PB160005.JPG

http://gallery.audioreview.com/data/...m/PB160005.JPG

http://gallery.audioreview.com/data/...m/PB160001.JPG

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Originally Posted by blackraven

I just purchased a used Class D Audio amp, the CDA-254S for $160.
Class D Audio CDA-254S Kit - Class D Audio Kits - PRODUCTS

Its in a wooden case but I am going to put it in this chassis-

Par-Metal

I'm giving it to my son to pair with his Maverick tube DAC/Preamp and his PSB B6's.

I'll give a review after we have had it for a few days.

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We await your report.

I suggest you should try the amp without as well as with filtering the sound though the Maverick's tubes. The CDA series amps are supposedly not quite as nice as the SDS series but I have no personal opinion in that I haven't heard the former.

Bill, from what I have read is that the CDA amps have a darker sound and some have said almost tube like compared to the SDS. They also do better with the larger power transformer. Unfortunately the one we are buying comes with the smaller 300va torroidal transformer. I may buy the 400va from antec for $75 depending upon how the unit sounds. Now I need to find a nice power button to put on the from of the metal case. Preferably a round one so that I can drill a hole for it to fit in.

If I like the CDA an SDS may be in my future. I would love to compare it to my Parasound. As it stands now, I am saving money to buy one of the new Van Alstine hybrid power amps which just blew me away when I took one home to review recently.

I am interested in what you think of this amp as well due to the fact that I will be replacing my Adcom at some point in the future and they are high on my list mainly because from what I heard they are tearing up the higher priced amps out there in both sound quality and power and for under a grand that is saying something.

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Originally Posted by blackraven

.... Now I need to find a nice power button to put on the from of the metal case. Preferably a round one so that I can drill a hole for it to fit in.....

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Something like this?

PV4 series illuminated anti-vandal switch | long life anti-vandal | sealed IP65 rating | www.e-switch.com

Thanks Blue's Man! That is exactly what I am looking for!

Well I just received my CDA-254 Class D amp today and I am blown away by the sound of this amp. I am running it with the Maverick Tube Preamp/DAC and a pair of PSB B6 speakers. First off, this is a very quiet amp. I can hear no background noise at all. The sound is very transparent with a very wide sound stage. There is good separation between instruments. It has great bass slam with tight well controlled bass. Dynamics are great and the amp seems very fast. Treble is excellent but could be a touch more detailed but I will know more about this when it place it im my reference system with my Van Alstine preamp and DAC. It has a silky smooth midrange. The over all sound is neutral when compared to the warm sounding 1976 vintage Technic's integrated amp that I was using.

I don't believe that you will find a better sounding amp at this price.

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Originally Posted by blackraven

Well I just received my CDA-254 Class D amp today and I am blown away by the sound of this amp. I am running it with the Maverick Tube Preamp/DAC and a pair of PSB B6 speakers. First off, this is a very quiet amp. I can hear no background noise at all. The sound is very transparent with a very wide sound stage. There is good separation between instruments. It has great bass slam with tight well controlled bass. Dynamics are great and the amp seems very fast. Treble is excellent but could be a touch more detailed but I will know more about this when it place it im my reference system with my Van Alstine preamp and DAC. It has a silky smooth midrange. The over all sound is neutral when compared to the warm sounding 1976 vintage Technic's integrated amp that I was using.

I don't believe that you will find a better sounding amp at this price.

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Excellent! I look forward to hearing how it compares to the Parasound in your main rig...

Any further thoughts on the new amp, BR?

I'm still enjoying it. It has a very intoxicating sound. It just sounds clean, airy and very smooth. I am going to place it in my reference system tomorrow. I have a feeling it may best my Parasound in certain aspects. I may also hook it up to the preamp out of my Adcom AVR 700 just to see how it sounds with a solid state preamp. I suspect that the amp really needs a tube pre to sound its best.

If I like it in my main system then I probably will buy the CDA-258, SDS-258, SDS-470 which is 300wpc at 8 ohms, 600 at 4 ohms and 800 at 2 ohms. I need to do some research on the specs. I may have a Parasound for sale.

Ok, I placed the amp in my reference system with mixed results. I had to roll some tubes because the amp sounded flat with the RCA Black plates in my preamp and sylvania's in my DAC. Once I did this the amp came a live. I am running Amprex 6CG7's in the preamp and Tung Sols in the DAC.

First off. The amp is dead quiet. No hiss and blacks are black. Compared to my Parasound A21 the amp is more quiet and there is no grain what so ever ( my one beef about the A21 is that it has a touch of grain). The amp also has more air, transparency and a wider sound stage. Bass seems a bit tighter and more controlled but there is a little less bass slam so its a trade off. The sound is more smooth but the midrange is not as prominent, probably due to the airiness of the sound. The A21 has better dynamics, deeper bass, more depth to the midrange and better treble resolution. The CDA-254 good treble but not harsh in the least, it sounds different but not in a bad way. People have commented about this on other reviews. Vocals are excellent very natural. The overall sound is very liquid. One thing about both amps are the dampening is excellent and noticable. These are both well controlled and fast amps. The dampening factors of Class D amps are in the thousands as is the A21.

Here are the Pro's and Con's for the CDA-254S

PRO'S-
Smooth well controlled sound
Tight well controlled bass
Wide sound stage, very transparent, airey sound
No Grain what so ever
Neutral souding
Very black background
Good dynamics but not on par with the A21 (more on this below)
Good treble with no harshness

CON'S-
-It needs the larger 400va power transformer that the CDA-254L comes with. The CDA-254S comes with the smaller 300va. I have read that with the larger transformer that the amp has much more slam, more powerful bass and is more dynamic. Note that when I used the amp with the PSB speakers, dynamics and bass slam was excellent. It was only when used with my more demanding Magnepans that the amp could have used the bigger power transformer.
-Midrange could have used a little more weight to it.
-Treble could use a little more detail and resolution

I don't think that I will be using this amp in my reference system but I probably will go ahead and buy th SDS-470 amp that puts out 600wpc at 4 ohms (the CDA-254S is 250wpc at 4 ohms) and has a massive power transformer. The SDS series is supposed to have better treble, dynamics and be of higher quality. I like the smooth sound, air, wider sound stage and very tight bass that this amp has. It has some of the qualities that the new Van Alstine 400R and 600R amps have, but they are out of my price range at $3K plus.

Overall the Class D amps are a bargain at $200-$400 for the kit versions. They give you a taste of audiophile sound at bargain prices.

Here are some specs on the Class D amps that may not be on the web site yet-

$175 Class D amp--120 wpc

Scroll down a few posts.

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Originally Posted by blackraven

Ok, I placed the amp in my reference system with mixed results. I had to roll some tubes because the amp sounded flat with the RCA Black plates in my preamp and sylvania's in my DAC. Once I did this the amp came a live. I am running Amprex 6CG7's in the preamp and Tung Sols in the DAC.

First off. The amp is dead quiet. No hiss and blacks are black. Compared to my Parasound A21 the amp is more quiet and there is no grain what so ever ( my one beef about the A21 is that it has a touch of grain). The amp also has more air, transparency and a wider sound stage. Bass seems a bit tighter and more controlled but there is a little less bass slam so its a trade off. The sound is more smooth but the midrange is not as prominent, probably due to the airiness of the sound. The A21 has better dynamics, deeper bass, more depth to the midrange and better treble resolution. The CDA-254 good treble but not harsh in the least, it sounds different but not in a bad way. People have commented about this on other reviews. Vocals are excellent very natural. The overall sound is very liquid. One thing about both amps are the dampening is excellent and noticable. These are both well controlled and fast amps. The dampening factors of Class D amps are in the thousands as is the A21.

Here are the Pro's and Con's for the CDA-254S

PRO'S-
Smooth well controlled sound
Tight well controlled bass
Wide sound stage, very transparent, airey sound
No Grain what so ever
Neutral souding
Very black background
Good dynamics but not on par with the A21 (more on this below)
Good treble with no harshness

CON'S-
-It needs the larger 400va power transformer that the CDA-254L comes with. The CDA-254S comes with the smaller 300va. I have read that with the larger transformer that the amp has much more slam, more powerful bass and is more dynamic. Note that when I used the amp with the PSB speakers, dynamics and bass slam was excellent. It was only when used with my more demanding Magnepans that the amp could have used the bigger power transformer.
-Midrange could have used a little more weight to it.
-Treble could use a little more detail and resolution

I don't think that I will be using this amp in my reference system but I probably will go ahead and buy th SDS-470 amp that puts out 600wpc at 4 ohms (the CDA-254S is 250wpc at 4 ohms) and has a massive power transformer. The SDS series is supposed to have better treble, dynamics and be of higher quality. I like the smooth sound, air, wider sound stage and very tight bass that this amp has. It has some of the qualities that the new Van Alstine 400R and 600R amps have, but they are out of my price range at $3K plus.

Overall the Class D amps are a bargain at $200-$400 for the kit versions. They give you a taste of audiophile sound at bargain prices.

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Nice review... Maybe the SDS-258 or 470 will correct the cons you found with the CDA...

Anyway, between Feanor's comparison of the SDS-258, your comparison of the CDA to the Parasound and all I've read, I'm sold on trying out either a SDS-258 or 470...

I'm going to e-mail Tom at Class D to determine which is better... As I'm a bit confused... I know the 258 doesn't double into 4 ohms, while the 470 does, however since the 470 is slightly cheaper I'd assume it trades off some quality for that ability to drive more difficult loads...

Thanks again for the review!

Anjani, the SDS-470 is basically 2x254's in one chassi. I would go for the 470 just for the added power and dynamics. You never know what speakers you may end up with in the future. The added power may come in handy.

I just place the Parasound back in the loop and it definetly has a more musical, warmer midrange with more depth but it is not as transparent. It's a trade off. I like both amps. I still prefer the A21 but there are many things I prefer about the CDA-254. I think at the prices that the Class D amps are being offerred it is a no brainer. And pairing them with a tube pre will certainly improve the midrange. I am I going to buy a Little Dot MKIII tube preamp to try with the amp. My son's Maverick Tube pre certainly warms up the midrange. I think the Little Dot with 4 tubes will be better than the Maverick with one tube.

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Originally Posted by blackraven

Anjani, the SDS-470 is basically 2x254's in one chassi. I would go for the 470 just for the added power and dynamics. You never know what speakers you may end up with in the future. The added power may come in handy.

I just place the Parasound back in the loop and it definetly has a more musical, warmer midrange with more depth but it is not as transparent. It's a trade off. I like both amps. I still prefer the A21 but there are many things I prefer about the CDA-254. I think at the prices that the Class D amps are being offerred it is a no brainer. And pairing them with a tube pre will certainly improve the midrange. I am I going to buy a Little Dot MKIII tube preamp to try with the amp. My son's Maverick Tube pre certainly warms up the midrange. I think the Little Dot with 4 tubes will be better than the Maverick with one tube.

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I got a reply from Tom:

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The 470 is able to drive tougher loads even down to 2 ohms. I would recommend the SDS-470. It’s pretty hard to best right now. The sonic quality is really about the same. Both excellent!

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So looks like I'll be getting a 470.

Note: I was wrong about the prices - the 258 complete amp is $565 while the 470 is $590, so the 470 is slightly more expensive (I think the 470 model I saw that is cheaper than the 258, did not include a transformer - which is why it is cheaper)...

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Originally Posted by blackraven

Anjani, the SDS-470 is basically 2x254's in one chassi. I would go for the 470 just for the added power and dynamics. You never know what speakers you may end up with in the future. The added power may come in handy.

I just place the Parasound back in the loop and it definetly has a more musical, warmer midrange with more depth but it is not as transparent. It's a trade off. I like both amps. I still prefer the A21 but there are many things I prefer about the CDA-254. I think at the prices that the Class D amps are being offerred it is a no brainer. And pairing them with a tube pre will certainly improve the midrange. I am I going to buy a Little Dot MKIII tube preamp to try with the amp. My son's Maverick Tube pre certainly warms up the midrange. I think the Little Dot with 4 tubes will be better than the Maverick with one tube.

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I'm confused about the SDS-470 -- is the extra power from bridging a pair of SDS?. The website only says, "SDS-470 amplifier with large power supply", which isn't very helpful (or even accurate maybe). I note that none of the SDS amps is rated into 2 ohms which is what a bridged amp driving 4 ohm speakers would see; so I'm a bit concerned about Tom's statement that the SDS-470 is OK for 4 ohms.

I seem to recall that the CDA amps have rather low input impedence; this means that they might not be a good match with high output impedance preamps. (The SDS have a higher 47 kohm input impedance which ought to be good with almost any preamp or passive.)

BR, review of the CDA vs. the A21 is very interesting.

I remain quite happy with my SDS-258 that I drive with a passive preamp. Whether you like passive or s/s vs. tube will depend on whether you like the tube effects. Actually I'd my thinking seriously about a Little Dot Mk III, but my expectation with that I'll get a warmer, more ambient sound with some loss of transparency.

Bill, I think that you will get more transparency with a tube preamp. At least that has been my experience with my limited expereince with tube preamps and tube DAC's. I am going to get the Little Dot and roll some better tubes in it. I doubt that it will replace my AVA preamp but it will go to good use in one of my other systems- MMG's in my basement and work out area or my Monitor Audio S1's in my bedroom. It will probably be with my MMG's. I am planning to buy another Maverick to use as a tube DAC/Pre with that Dayton DTA-100a amp that I am using with my Monitor Audio's.

You guys keep talking good things about these amps and I am going to have to try one for myself since they seem to be competitive with amps way above their price range and the build it yourself thing is something I grew up doing so that does not bother me at all. very very tempting.

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Originally Posted by Feanor

I seem to recall that the CDA amps have rather low input impedence; this means that they might not be a good match with high output impedance preamps. (The SDS have a higher 47 kohm input impedance which ought to be good with almost any preamp or passive.)

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I can't recall the exact numbers, but I remember reading a few hundred pages of reviews for this company on a different forum, that Tom will change the input impedance to match your pre-amp. It seemed to be a common complaint with the earlier models and folks were having them built with higher impedance at no charge, but it took a day or two longer.

It's worth a shot to sling Tom an e-mail to see what values he can change the input value before you order.

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Originally Posted by salad 419

I can't recall the exact numbers, but I remember reading a few hundred pages of reviews for this company on a different forum, that Tom will change the input impedance to match your pre-amp. It seemed to be a common complaint with the earlier models and folks were having them built with higher impedance at no charge, but it took a day or two longer.

It's worth a shot to sling Tom an e-mail to see what values he can change the input value before you order.

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Your exactly right. Also, the SDS amps come with adjustable gain pots.

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Originally Posted by blackraven

Your exactly right. Also, the SDS amps come with adjustable gain pots.

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Thanks for refreshing my memory. I forgot about the adjustable gain pots on the SDS models.

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Originally Posted by harley .guy07

You guys keep talking good things about these amps and I am going to have to try one for myself since they seem to be competitive with amps way above their price range and the build it yourself thing is something I grew up doing so that does not bother me at all. very very tempting.

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Harley, these amps have a different sound than SS and tube amps. They are somewhat similar to the Nuforce Model 9's in sound. I can't tell how similar because the Model 9's that I have heard are on my freinds reference system with an AR line stage tube preamp and PSB Synchrony one speakers. I guess they both sound smooth, grain free, with air and transparency. Treble seems similar. Bass is very tight and controlled. So you might really like the sound.

There is a guy on the AC forum that was having a hard time deciding whether he liked one of these amps better than his $14K class A amp which I find a little hard to believe.