[wushuliu]

How would the $175 kit shown here compare with say an Emotiva UPA-2?

From the Affordable Audio review:

"There are better amps out there, but you aren’t going to touch this sound quality
for under a grand even on the used market."

[toxteth ogrady]

From the Affordable Audio review:

"There are better amps out there, but you aren’t going to touch this sound quality
for under a grand even on the used market."

And I think that number is being conservative.

looking forward to hearing what my sds-258 sounds like after being paired with either the DCB1 and Lighter Note LDR kit I'm building.

Cheap and cheerful is right

[poseidonsvoice]

How would the $175 kit shown here compare with say an Emotiva UPA-2?

I think if you read my review here, any residual audiophile nervosa will just drift away. However, bear in mind that my review was based on the SDS254 which is the SuperD version for amp module alone is about $235.

Anand.

[srb]

How would the $175 kit shown here compare with say an Emotiva UPA-2?

I think if you read my review here, any residual audiophile nervosa will just drift away. However, bear in mind that my review was based on the SDS254 which is the SuperD version and is about $235.

The SDS-254 is $235 for the amplifier module only, and $310 for the kit (with power supply board and transformer).
 
Steve

[poseidonsvoice]

 
The SDS-254 is $235 for the amplifier module only, and $310 for the kit (with power supply board and transformer).
 
Steve

Yup, thanks for the clarification.

Anand.

[siava1018]

is it possible run these on batteries? How does the SDS compare to the virtue one.2?

[poseidonsvoice]

is it possible run these on batteries? How does the SDS compare to the virtue one.2?

Yes.  See here.

Anand.

[siava1018]

Where can I get the PS board from? Is it possible to do a DIY one?

[srb]

Where can I get the PS board from? Is it possible to do a DIY one?

http://classdaudio.com/index.php/products/power-supplies/12v-dc-switching-power-supply-500-watt-car-audio.html

This one takes a 12VDC input and outputs +/- 50VDC.  You could search on eBay for alternatives or kits that have similar specs. 
 
Steve

[raindance]

I just built an amp using the CDA254 PCB. It sounded a bit thin and nasty at first due to it's low input impedance so I built a unity gain buffer using a pair of LME49710 op-amps and added a 12V regulated PS to drive this. I am feeding it from a home brewed stepped attenuator balance control and a 100K (cheap) log pot. It sounds magnificent!!! It is probably the best sounding amp I've heard in my system and I've had a lot. It is not tube-like in that I don't find it very warm, but it is sweet and extended at the top, extended at the bottom, and probably a bit lean in the midbass. The only issue is that the class D amp really needs a gain stage rather than a unity gain buffer, so I'm looking for ideas for a great sounding tube circuit with a gain of 3. I want 50K - 100K input impedance and an output impedance of 200 ohms or less. I would prefer to use 12AU7 tubes or 5670's as I have a stock of those.

Any ideas for me?

[Meicheng]

This last post begs the question, what is everybody using for a preamp with their Class D power amps.  I would love to hear from as many people as possible who are using the Class D amp, as to what preamp they are using.  I'll start off by saying I'm using the Audio GD P2 solid state preamp and its a pretty darn good combo, but I have the itch to try a tube preamp...  Thanks, Martin. 

[roymail]

Many are using the Pass B1 buffer/pre which is zero gain, and I've have not read any complaints about needing more gain.  I'm sure others will jump in here to comment.

Are you aware that the gain can be increased on the CDA series amps from 26db (standard) to 32db (high gain).  That is twice the amount of gain increase you mentioned.  If you don't know already, email Tom to find out which gain setting your amp board has.

Let us know.

[jtsnead]

I got into class D stuff with the Virtue line of amps a One-2 this led me to build an SDS-254 which I used both the Virtue and ClassD with my Modwright
SWL 9.0SE tube preamp.

Both systems sounding great, I liked the ClassD a little better, but was
intriqued about how good a low price amp could sound in my system.
With the ClassD amp I had so much gain that I adjusted the pots lower
to 5 ohm setting to allow better range of volume control, which made me
wonder do I need a preamp at all, but I have always really liked tube preamps.

So I started reading the threads on Dodd battery powered buffer, this might be the way to go as far as the cleanest signal to the amp. Well in the mean time
I sold mt 9.0SE and bought a Signature version of the 9.0SE with tube power supply, definite upgrade mainly in lower bass. The difference in cost was not that much so I fiqured I could not loose.

Which brings me back to what if the preamp was less of influence on the signal
ie: the difference between the tube rectified 9.0 and the standard version?

I have been following the Virtue threads because the tripath amp is a really good sounding amplifier. Virtue had a sale on their Model 901 with a Dodd buffer installed, which also can be ordered with a battery power supply, had to order it to see how it will compare to my preamp with the SDS-254, I have a feeling that it will be a close match. I do not need the gain with the ClassD amp, so trying the 901 with it on battery is a promising situation, plus I get a tripath amp along with it to compare to the ClassD.

The bottom line is that I think a tube preamp is the best match with any type
class D amp, if you do not need alot of gain than a buffer might be the best
match. Stay tuned I will post my thoughts once I receive the Sensation 901
which I will use a battery powered tube buffer preamp first before I compare the amp sections. Fun Fun Fun!!

[steve k]

I'm using a VTL 5.5 tube preamp with my Class D amps. I used to have an all tube system so now only my preamp is tubed. I love the combination with the Class D. The VTL is a very neutral sounding preamp for tubes but still adds the holographic imaging of tubes and brings out the sweetness in the mids where most of the sweetness in the music is--strings, vocals, piano, horns etc.
steve

[dvenardos]

The Classic Two with auricaps and Two.2 with sonicaps sound much better than Classic One with VirtueCaps and Two.2 with virtuecaps. If you ordered the M901 with either auricaps or sonicaps I think you will be surprised at how much nicer it sounds. Looking forward to hearing your comparison.

I got into class D stuff with the Virtue line of amps a One-2 this led me to build an SDS-254 which I used both the Virtue and ClassD with my Modwright
SWL 9.0SE tube preamp.

Both systems sounding great, I liked the ClassD a little better, but was
intriqued about how good a low price amp could sound in my system.
With the ClassD amp I had so much gain that I adjusted the pots lower
to 5 ohm setting to allow better range of volume control, which made me
wonder do I need a preamp at all, but I have always really liked tube preamps.

So I started reading the threads on Dodd battery powered buffer, this might be the way to go as far as the cleanest signal to the amp. Well in the mean time
I sold mt 9.0SE and bought a Signature version of the 9.0SE with tube power supply, definite upgrade mainly in lower bass. The difference in cost was not that much so I fiqured I could not loose.

Which brings me back to what if the preamp was less of influence on the signal
ie: the difference between the tube rectified 9.0 and the standard version?

I have been following the Virtue threads because the tripath amp is a really good sounding amplifier. Virtue had a sale on their Model 901 with a Dodd buffer installed, which also can be ordered with a battery power supply, had to order it to see how it will compare to my preamp with the SDS-254, I have a feeling that it will be a close match. I do not need the gain with the ClassD amp, so trying the 901 with it on battery is a promising situation, plus I get a tripath amp along with it to compare to the ClassD.

The bottom line is that I think a tube preamp is the best match with any type
class D amp, if you do not need alot of gain than a buffer might be the best
match. Stay tuned I will post my thoughts once I receive the Sensation 901
which I will use a battery powered tube buffer preamp first before I compare the amp sections. Fun Fun Fun!!

[soundnoob]

dvenardos: Do you have the SDS and the Virtue? which one do you like better?

Thanks! I just received the SDS-254 and the Virtue was something I was thinking about before going with the SDS.

[6SN7]

I'm using an AMC CVT1030 tube preamp.  It's been modded over the years, and with the latest addition of PIO coupling caps, it's sounding better than ever.  I've enjoyed the way it sounds with various solid state and tube amps (mostly tube), but it's at it's best with my bridged CDA-224's.

[toxteth ogrady]

After hearing my newly born sds-258 amplifier a couple weeks back my initial impression was that it would benefit from being paired with a good tube linestage. At that early stage the sound was very smooth but tonally dense in the midband. It wasn't bright in any way, just thick for lack of a better word, and I wanted to hear it open up the way it so effortlessly does with my class A Accuphase integrated.

The sound has changed since my initial impressions, namely that the midband is far more refined and everything has spread out a bit. The transparency is superb. With the sound I'm achieving now I've decided to abandon the idea of pairing the amplifier with a tube linestage, opting instead for either the Pass inspired DCB1 or the Lighter Note light dependent resistor volume control, both of which are on the bench for assembly.

Regarding the change in sound of my amp, I'm not sure what to attribute it to. The only difference is the amp has had additional time to play and also about two weeks ago I changed the magnet wire I was using to 10 gauge Belden and replaced the stock AC cord to a Pangea AC-9 power cord.

It's not the equal of my Accuphase, not yet anyway, but it is close enough that I'll likely sell the Accuphase and have a vinyl shopping bonanza with all the money I pocket. For my high current needs, I have a hard time imagining a more satisfying purchase.

[roymail]

I've decided to abandon the idea of pairing the amplifier with a tube linestage, opting instead for either the Pass inspired DCB1 or the Lighter Note light dependent resistor volume control, both of which are on the bench for assembly.

Thanks for the report.  You must feel that there is no need for an additional gain stage since both the Pass and LDR volume control provide no added gain.  How sensitive are your speakers?

[toxteth ogrady]

Thanks for the report.  You must feel that there is no need for an additional gain stage since both the Pass and LDR volume control provide no added gain.  How sensitive are your speakers?

We'll see about the gain once I'm finished with the DCB1. Right now I'm using the preamp section of the Accuphase.

The speakers I have the amp paired with are Ohm Walsh 4.3000's. Essentially vintage Ohm Walsh 4's fitted with Ohm's most current drivers. Even with their 90db rating(need to check on this) Ohm's are notorious for requiring lots of current to sound their best.