Review and Measurements of IRS2092 IRAUD350 Class D Amplifier

[prighello]

@MattG one of the differences I know for sure regarding the SDS vs CDA amps from Class D Audio is the SDS amp has better heat sinking with the sink attached to the chassis. Obliviously there are the XLR inputs and the input attenuators as well.

The amps still are not very sensitive needing 2V for full power and have lowish input impedance thus a real preamp with gain is best or if using a strong digital source a buffer for impedence matching.

As the owner of one of the SDS amps I'd be interested to see it measured. I wonder how different it is from the IR reference design? Hopefully the amp measured in this thread is not indicative of IRS 2092 based amps. I will say I was impressed with the build quality of the internals of the SDS amp.

 

[MattG]

@MattG one of the differences I know for sure regarding the SDS vs CDA amps from Class D Audio is the SDS amp has better heat sinking with the sink attached to the chassis. Obliviously there are the XLR inputs and the input attenuators as well. (...) I will say I was impressed with the build quality of the internals of the SDS amp.

Which SDS model do you have, and when did you get it?

Being generous, I might be able to take a little credit for some of the SDS construction. I had a couple SDS-470 amps back in 2013, they were actually new/unlisted on the site at that time. I went the DIY route with the first one, buying only the amp module, and pairing it with a Connex SMPS800 power supply. I put the amp module and PSU in a fairly small (but vented) chassis (basically, just big enough for the two components) and had heat issues, even with very modest loads. I worked with Tom (the man behind Class D Audio) a fair amount. He eventually revised the design. The original SDS-470 had the same heat sink as the lower-powered modules. But he changed it to additionally have heat "slugs" that connect the heatsink to the bottom chassis panel. My second SDS-470 was purchased as a finished product. I don't have either of those amps any more, having sold them a while ago.

 

[prighello]

Which SDS model do you have, and when did you get it? Being generous, I might be able to take a little credit for some of the SDS construction.

I have the SDS 470C. I think I got it at the end of 2015 and it is the revised heat sink model. Glad it was revised, mine never really gets hot even when I've ran it with Magnepan MMGs or Kef LS50s. It sounds fine to me, bass seems more robust than other amps I have used. My only knock is the input impedence and voltage requirements and lack of 12v trigger which I think has been addressed in newer versions.

 

[chebum]

Hopefully the amp measured in this thread is not indicative of IRS 2092 based amps.

I have a Pioneer SC-LX57 receiver which is powered by the same chip. It's very good in terms of dynamics but extremely noisy. If you connect the amp directly to a compression driver, the noise is unbearable. I made a -15db attenuator and still I can hear a little bit of hiss. The noise level is adequate for "standard" speakers though.

 

[Horst Schlawutzke]

Thank you for the review. I registered just to post this, as the google search result for "irs2092 THD" was way better than expected. I really hate the spec sheet fakery and leaving out essential data. You saved me hours and a lot of money.

 

[Gorgonzola]

I have a DIY Class D Audio SDS258 which, of course, is also based on the IRS2092 chip. I assembled this over a decade ago and today it's my backup amp.

A long while ago I upgraded the original Class D Audio linear supply with at Connexelectronic board, doubling the capacitance. I notice no difference at all in the sound. More recently upgraded again, this time to an SMPS, the Connexelectronic SMPS800RE. The sound is at least as good, subjectively, as the linear power supplies -- maybe better. The weight of the amp is much lighter which was my main reason for the upgrade.

 

[joenetic]

Thank you for the review. I registered just to post this, as the google search result for "irs2092 THD" was way better than expected. I really hate the spec sheet fakery and leaving out essential data. You saved me hours and a lot of money.

The irs2092 reference design board performance match the data sheet, I think the bad measurement result of this review diy amplifier was caused by the bad implementation and parts, the output inductor quality is very important, the PCB layout is also very critical, I have irs2092 amplifier from China by another e-shop, it is very good sound quality.

 

[jschwender]

I can confirm that my version of IRS2092 amplifier shows data that matches the data sheet values. I use these amps in prosound boxes, i don't consider the specification good enough to utilize it in audiophile application, the noise floor is just too high. In a prosound box the prevalence is clearly on high power + low weight and the distortion and noise data is good enough for this application. You find the IRS2092 driver also in 4 kW amps. In general it is right that the filter cores and filter capacitors are very critical parts in digital amplifiers. Even more critical for a digital amplifier for any application is that the load impedance must be perfectly matched to the filter impedance. If the amplifier output filter is tuned to 4 Ohm, an 8 Ohm load results in very different behaviour. Also Impedance peaks or gaps must be properly compensated by zobel networks. As the output filter is a high power high frequency filter, the filter inductance must have minimized not only Rdc but also the current displacement and proximity effect, combined with high saturation limit. This is a significantly different requirement compared to a passive crossover part. So i would also conclude that these bad test results are implementation specific.

 

[DWPress]

I recently had some eBay credits to dispose of so took a chance on this version which is single channel and had the needed XLR input.

Just got it a few days ago, based on this review I tore it apart to see how well it was put together and how safe it might be. I replaced the ground wire with something heavier, sanded away the anodizing so that it made better contact with ground and also where the sidewalls and lid join to continue ground throughout the entire case. I was surprised that everything was soldered to pads below the board, not using the screw connectors but since it's single channel BTL I guess it makes sense. I rerouted some of the signal cables from out underneath the power supply but didn't desolder to add any twists, since this is just for sub use I figured what little gains to be had weren't really necessary.

Before:



After:



Overall, I'm quite pleased. It seems to drive the sub just fine. Since I paid less than $170 shipped I'm exceeding happy with the case actually - solid construction with 3mm bottom, rear and sides at the thinnest along with a 6mm front. I've paid more for empty cases in the past!