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SounDigital SD300.2D Review (Car Amplifier)

amirm

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This is a review and detailed measurements of the SounDigital SD300.2D stereo car amplifier. It is on kind loan from a member. Apparently only 200 of these were built using GaN transistor technology. Not sure of the original cost ($1,300?).

From outside, the SD300 looks plain and and budget like:

SounDigital SD300.2D Review GaN Class D stereo car amplifier.jpg


This is no frills amplifier with large terminals for power, speakers and that is all she wrote. Did not get a manual so don't know what the power, X and triangle do. All web page references to it are gone.

SounDigital SD300.2D Measurements
I powered the unit using my Lithium custom power bank (rated for 100 amps continuous, 300 amps peak). Test voltage was nominally 13.4 volts and drop to 12.9 at peak power. Here is our dashboard:

SounDigital SD300.2D Measurements GaN Class D stereo car amplifier.png


Wow, this is stunningly good for a car amplifier. Actually, it would beat some 90% of the home amplifiers I have tested! Distortion is less than half of company spec.

Signal to noise ratio likewise, ranks up there especially in the good channel:
SounDigital SD300.2D Measurements SNR GaN Class D stereo car amplifier.png


Frequency response shows that the amplifier filter does cause load dependency but it is at high enough frequency that should not be audible:


SounDigital SD300.2D Measurements Frequency Response GaN Class D stereo car amplifier.png


Crosstalk is good:
SounDigital SD300.2D Measurements crosstalk GaN Class D stereo car amplifier.png


The amplifier took no time to reach stable operation:


SounDigital SD300.2D Measurements Warm up GaN Class D stereo car amplifier.png


Multitone test showed weakness at very low frequencies and high (latter being typical):

SounDigital SD300.2D Measurements Multitone GaN Class D stereo car amplifier.png


Fortunately the threshold of hearing is quite high in low frequencies so I don't expect an audible problem there.

Testing for power we get:

SounDigital SD300.2D Measurements Power into 4 ohm GaN Class D stereo car amplifier.png


Allowing for more distortion and peak we get a bit more:

SounDigital SD300.2D Measurements Max and Peak Power into 4 ohm GaN Class D stereo car amplifier.png


And 8 ohm:

SounDigital SD300.2D Measurements Power into 8 ohm GaN Class D stereo car amplifier.png


So not a barn burner you would want to use for a sub and such.

I removed my AES filter and measured the full output spectrum:
SounDigital SD300.2D Measurements FFT GaN Class D stereo car amplifier.png


Typical class D amplifier operates at around 300 kHz. Courtesy of GaN transistors, this has been upped substantially to 800 kHz. This is why the filter ringing was pushed up correspondingly in frequency response test. Very nice.

Edit: forgot to post the stepped frequency test:

SounDigital SD300.2D Measurements Power into 4 ohm vs Frequency GaN Class D stereo car amplifier.png


Conclusions
When I test car audio gear, I automatically lower my expectations. Imagine my surprise when I saw the dashboard and how the SD300.2D outperforms majority of home amplifiers let alone car audio. Some smart designer in Brazil really took advantage of GaN technology to produce very low distortion and high performance amplifier. Alas, if it cost $1,300 for so "little" power, I can see how it would not sell as a mainstream product. Hope we see some variation of this come back to market and at higher power levels.

Oh, I forgot to note that the amplifier just got a bit warm during testing. So it is very efficient to boot.

It is my pleasure to recommend the SounDigital SD300.2D. A feather in the cap of our Brazilian members and visitors! :)

------------
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martijn86

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Don't judge a book by its cover? Some of the most hifi, luxurious looking amplifiers and receivers can't reach this performance and this automotive amplifier (from SoundDigital :D) just smashed in 19 bits dynamic range (A-weighted, which in a noise box like a car, seems like an honest way of measuring).

Really cool to see more GaN experiments floating to the surface. I wonder if a Hypex or Purify team is already exploring possibilities.
 

Matias

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Impressive. But I think it might be discontinued as I cannot find this model on the company's website. I found a post on Facebook from 2015.

It was a limited edition. Only 200 units were made.
 

Jorj

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It's important to remember that many custom car audio systems are running down into the 1 and even 1/2 ohm resistance. 2 ohms is considered average, and it's been a long while since I found one that was actually operating at 4 ohms. Most amps in the car world are tested and rated by their stability at low resistances, along with power output and distortion. I'd be surprised if this amp did not shoot way up to around 1300 watts summed mono into 1 ohm. What would be interesting is how the distortion reads when run in that configuration.
 

PeteL

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It's important to remember that many custom car audio systems are running down into the 1 and even 1/2 ohm resistance. 2 ohms is considered average, and it's been a long while since I found one that was actually operating at 4 ohms. Most amps in the car world are tested and rated by their stability at low resistances, along with power output and distortion. I'd be surprised if this amp did not shoot way up to around 1300 watts summed mono into 1 ohm. What would be interesting is how the distortion reads when run in that configuration.
I highly doubt that. My guess would be something like 400 Watts bridged in 2 ohms. 1 ohms, remains to be seen if it's stable. Yes this at least should have been tested in 2 ohms, but even being optimistic on how this would translate, this is a very weak power amplifier for car audio that should cost 200 bucks. In my opinion if they only made 200 is because it simply isn't competitive, let alone a home run of a product.
 

Vini darko

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I highly doubt that. My guess would be something like 400 Watts bridged in 2 ohms. 1 ohms, remains to be seen if it's stable. Yes this at least should have been tested in 2 ohms, but even being optimistic on how this would translate, this is a very weak power amplifier for car audio that should cost 200 bucks. In my opinion if they only made 200 is because it simply isn't competitive, let alone a home run of a product.
It's a sq not spl amp. You dont need a gizzillian watts to run mids and tweeters.
 

KxDx

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Wish I still had that Alpine PDX F4. I'd have sent it to you for testing.
 

bravomail

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for cars, something like famous $20 LePai amp would work. noisy env!
 

jannek

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There MUST be someone in north America owning an Alpine PDX F6 to send it to Amir?! Let alone an Eton Core A2...
 

GWolfman

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A pleasant surprise (particularly for car audio)!
 
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I was surprised to see your test. Very interesting!

I am Diogo Ianaconi, CEO of HKI USA and Export Director for SounDigital USA. Any questions you may have about the GAN Project please let us know.

We have big plans for 2022 with the release of 4 new GAN amplifiers.

From our initial tests, they are much superior than our original Limited Edition model.

For more information - www.hki-usa.com
 
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I highly doubt that. My guess would be something like 400 Watts bridged in 2 ohms. 1 ohms, remains to be seen if it's stable. Yes this at least should have been tested in 2 ohms, but even being optimistic on how this would translate, this is a very weak power amplifier for car audio that should cost 200 bucks. In my opinion if they only made 200 is because it simply isn't competitive, let alone a home run of a product.
That is incorrect. We only did 200 because of the limited supply of specific GAN Fets at the time this project was conceived. With the potential regarding sound quality of this SounDigital GAN project, we have worked for long time on designing a more high end heatsink and so on, to be able to release a full range of GAN powered amplifiers.
 

GWolfman

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That is incorrect. We only did 200 because of the limited supply of specific GAN Fets at the time this project was conceived. With the potential regarding sound quality of this SounDigital GAN project, we have worked for long time on designing a more high end heatsink and so on, to be able to release a full range of GAN powered amplifiers.
Why do you need a "more high end heatsink" with GAN? Isn't GAN significantly more power efficient, with lower demands on cooling? If I understand correctly, you can go smaller (same output) or go with more power (same heat dissipation), or somewhere in between.
 

Doodski

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Sorry if I did not explain correctly.

I am talking purely cosmetics. In our car audio market, if we release GAN amplifier with the same look as the original GAN we had, it will not have great sales, even if it is the best amplifier ever. People many times buy with their eyes. :)
What is the maximum current consumption @ maximum output of the amp @amirm tested here?
 
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