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Price: $245.00
Product ID : SDS-250 Module
Manufacturer: Class D Audio USA
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Our new Super D Series audio power amplifiers are built on the highly acclaimed reputation of our CDA series amps. Our goal was to keep the excellent sonic qualities while adding a state-of -the art balanced input stage (also accepts standard single ended input) and external adjustable gain controls. We've also added a better cooling system, Molex connectors for external LED's, power switch, and gain controls (included). The balanced input stage is one of the finest available and normally only found on very expensive high-end equipment. When using single ended inputs, you can change a jumper to select inverted or non-inverted input as well... useful in some instances. The gain controls included with this kit feature a conductive plastic element for ultra low noise. Our Super D Series amps provide more life-like imaging and sound stage, along with the beautiful smooth tube-like sound we're known for. These amps are powerful, clean, quiet , and transparent. Specifications: · Output: 250 X 2 - 4 Ohm, 125 X 2 - 8 Ohm · Bridged Output: 500W X 1 - Bridged 8 Ohm (Full Bridge) · THD+N, 1W - 1KHz: Better than .02% · Dynamic Range: 101 db · Efficiency: Over 90% · Required Power Supply: +/- 40 Volts DC to +/- 50 Volts DC Accepts Balanced or Single Ended inputs at up to 18 volts. Input Impedance: 47K More specs coming soon. 1 Year Parts and Labor Warranty

Model SDS-250
Number Of Channels 2
RMS Power Per Channel 8 Ohms 125W RMS X 2
RMS Power Per Channel 4 Ohms 250W RMS X 2
RMS Power in Bridge Mode 500W Into 8 Ohm Only. Single Channel
Input Sensitivity 2V
Total Harmonic Distortion (THD) Better than .02% (normal listening is about .003%)
Frequency Response 10hZ to 35KHz
Input Impedance RCA 30K
Input Impedance XLR 45K
Voltage Gain for RCA Input Adjustable
Voltage Gain for XLR Input Adjustable
Power Requirements +/- 42 Volts DC to +/- 50 Volts DC
Dimensions (W x H x D) Inches 4.25" X 1.5" X 5.5"
Dimensions (W x H x D) Millimeters 108.0 X 38.1 X 139.7
Product Weight (lbs/kg) 1.5/ 0.7
Shipping Weight (lbs/kg) 2/ 0.9
Manufacturer Class D Audio

Product Reviews

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Reviewed by customer
08/15/2016 - 02:10:55 PM
Easy build, enjoying the amp.
I just completed the SDS 254 kit and am using it as an upgrade to a CDA 224 purchased on Ebay a while back and now used for surrounds in my home theater set up. I went to the SDS 254 as a result of satisfaction with the CDA amp. I gave up tube amps for several years because of the upkeep and the person who maintained them had retired. The ClassDAudio amps brought back the same enjoyment of music I had once with tubes. I have also enjoyed building the SDS amp, have not had so much fun since Heathkit and Dynaco went out of business. As to building the kit, admittedly a lot of helpful details were not including in the instructions. For example, the package I received did not include the Molex connectors for the volume controls (which I really did not need). However, in Emails, Tom explained they were out of Molex connector and gave instructions on where on where to put the jumpers to by bypass the volume controls. Also, instructions were given on assembling a kit with the CDA boards, but not the SDS, which are slightly different. Again, through Email, Tom attached a one page document with that information. It would have been helpful to have had that information included in the shipment. As others have indicated, Tom was always helpful and would respond in a timely manner for any problems in assembly. I have had the SDS up and running for several days now. While I lack the expertise of an refined audiophile, it is a step up from the CDA, which is a fine amp in its own right. Bass is very deep and well defined. I have had to cut back on the bass controls on my preamp. I am noticing, as others have stated, new details in familiar recordings. Stereo image is excellent. Center voices and instruments are well placed in the center, regards of your location in the room. My system includes a pair of Classic Infinity 2000a speakers with electrostatic tweeters. The CDA sounded nicely, but these speakers can take a lot power. My preamp has balanced outputs, which is another reason for going for the SDS. I am now in my early 70's and have been hooked on audio systems since I was a teenager. I can honestly say this is the best system I have had ever.
Reviewed by customer
08/15/2016 - 02:10:14 PM
SDS 254
Well I would say: a Classdaudio what else?
Great sound, well build/engineered
My 300B tube amp is for sale.
What can I say more? Just hear the classdaudio and it will tell you...
Reviewed by customer
08/15/2016 - 02:09:35 PM
Follow up on my previous SDS-254 review
I changed the tube in my DAC to a GE 5 star 5670 tube and it gave me a significantly improved midrange an treble. I have tried three different tubes and each time it was easy to hear the differences between the tubes. Many reviewers say that the ease of hearing upstream changes is the mark of a good amplifier. I am really pleased with the amp.
Reviewed by customer
08/15/2016 - 02:08:58 PM
A fine sounding amp
I have been listening to this amp for a couple of weeks and I believe this is the nicest overall sounding amp I have ever owned.

It delivers ample bass. My Ohm 1000's sound as if they have a sub-woofer attached. I have been going through my jazz recordings that have a good amount of acoustic bass in them and smiling.

I am hearing hall sounds fairly clearly on most recordings. The amp gets the timber of string sections correct, that is the balance of woody resonance and steely overtones. I listen to a good amount of classical music so this is important to me.

The midrange is very good also. It is not quite the same as my single ended tube amps but it is close. The sound stage sounds deeper than with my tube amps.

I would recommend this amp to anyone. It is going to be my main amp for the foreseeable future.
Reviewed by customer
08/15/2016 - 02:08:10 PM
World Beater
Dear Class D Audio enthusiasts,

I was just lucky enough to have jtwrace send me a Super D amp to listen to. My audition period lasted about 5 days while my family was out on R&R.

First and foremost, jtwrace is a gentleman and he promptly mailed the amp to me (we are only 60 miles from each other). The build quality is excellent and in fact, if you are even tempted to think about a case for the amplifier, I will say that his case is awesome. Remember he is in the racing industry (NASCAR was born in Charlotte), so all the hole punching, drilling and engraving/lasering of the nameplates are done. The case is also ready for any of Class D audio's amps, including the SDS series (Super D). Needless to say, I promptly purchased one from him, and you can find out his e-mail info on this website.

The amp completely outclassed my dual mono gainclone which uses Peter Daniel's LM3875 souped up chip amplifiers with dual mono 400VA Plitron transformers and a pair of Lundahl 1676 input transformers (for balanced input and to adjust the gain between 24 dB/30dB). The commercial equivalent of this amp lists for about $2400, and is sold right here: More open on top and tighter in the bass, but also more wider and deeper soundstaging. I had no listening fatigue with this amp and I could play it at even louder levels than I usually do. Microdetailing was about the same as my gainclone but definitely more macrodetails (of course the 125 watts helped!). My speakers are GedLee Abbeys and the unit is DEAD QUIET on 95-96dB/2.83V/8 ohm sensitive speakers. The input impedance of 47K allows the amp to be used with nearly any preamplifier or directly from your source. The balanced topology is icing on the cake and that is how I auditioned this product, with the XLR inputs.

I'll be building mine soon, probably with Jensen 4 pole caps or Mundorf Electrolytics in the power supply just for kicks. Although I do have other chassis, I chose jtwrace's because my other chassis have heatsinks which you don't need for this amp (it would be a waste of a chassis).

Thank you Tom, jtwrace and all other Class D Audio enthusiasts. This fella is a world class amp and should be on your short list if you are auditioning units below $3K.

Reviewed by customer
08/15/2016 - 02:07:25 PM
Nice amp...
I have both the SDA and the CDA and I can say the SDA is a more refined sound, clearly better. I like it better than the outlaw 220 mono or the Emotiva BPA-1 run as mono. Does it sound better then a 3000 dollar Cary, not not really but come on get real. This is an awesome setup for around $300 and a couple hours of sweat equity you will have something you can be proud of. If you were to buy the kit and add a second module for right around 500 smackers the dynamics and power go through the roof and they you are talking big power, big sound!

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