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noah katz 21st September 2012 04:02 AM

Which IRS2092 modules?
I’m going to build a 12-ch amp for my HT system.

My problem is deciding which of your many IRS2092 modules to use.

The only obvious differences to me are the form factors, storage cap sizes, and the extra features of the CxD250-HP (which I don't need).

I want about 150 W/ch @ 8 ohms, which gives me the following options in ascending order of $/channel:

- CxD300-8R $33/ch 35x95x35 mm Connexelectronic

- ScalD_Amp $50/ch dimensions? Connexelectronic

- ScalD_Amp2 $53/ch 100x100x42 mm Connexelectronic

- CxD250-HP $89/ch dimensions? Connexelectronic

Are there any significant sound quality difference between these?

If not, what accounts for the price differences?

Also, I need advice on what to do about speaker protection.

I was going to use your protection modules but am unsure what to do after reading this:


Originally Posted by Bruno Putzeys (
This question is answered once every 100 pages of this thread or so. The gist of it is, as spelled out in sections 7.2 and 8.1 of the data sheet, use a supply that shuts down when pin 5 of the power connector is pulled low. This pin is pulled low when the NC400 finds the speaker output stuck at a high voltage.

The SMPS600 has this function. If, for reasons of philosophy*, you want to build your own linear supply, add disconnect relays between it and the power amp and make them respond to this line.

DO NOT USE SPEAKER RELAYS. Speakers are inductive little buggers and will sustain an arc across the relay contact long enough for it to weld shut. Speaker relays CAN AND WILL FAIL at the exact moment that you need them.


*Reasons of philosophy such as "not believing a switching supply sounds good and therefore concocting a linear contraption and then complaining about the result" ;)

Do the IRS2092 modules include similar protection?

Thanks very much

Cristi 21st September 2012 10:21 AM

For your purpose I recommend to use CxD300-8R modules Connexelectronic basic version, 200W 8R. These modules have all the basic protections such as under-voltage, over-voltage, over-temperature, over-current and short circuit, but not the DC protection with relay disconnect for speakers. This protection can be implemented outside of the board, either with a classic speaker protection circuit using a high breaking current/voltage relay able to safely break 50-60V at 10A without welding its contacts or even with solid state relay (version "under construction") which is able to break higher voltages without any risk of failure.
The power supply which will be available for the CxD250-HP will have the option of quick-disconnect in case of DC failure on one or both of the outputs. Other modules powered from this SMPS will be protected too, so the use of the classic speaker protection circuit along with any IRS2092 based amplifier when powered from that SMPS will become redundant.
IRS2092S IC have

noah katz 21st September 2012 06:43 PM

OK, I will order 12 of theCxD300-8R modules.

The data sheet

for the relays in your SPC1 show that they're only rated for 5A.

Can you supply them with the 10A JW1FSN-DC12V?

Other questions related to construction:

One of the layout options is to put all twelve modules next to each other, but they will barely fit in the case; is it OK for the heat sinks to contact each other?

Do the modules come with a wiring diagram?

I see the PCB has labels, but I'd rather not guess, as I'm not really an electronics person.

For example, is GND for both chassis and signal, or should they be isolated?

Do you know the part number for a plug to match the white 3-pin connector modules?

Thanks very much

Cristi 22nd September 2012 03:59 PM

A 5A rated relay can be used for several hundred Watts since the average current of such amplifier which pass through relay is less than 5A, only the short term peaks are exceeding the 5A rating. Relays have been used to protect speakers since 20-30 years or even more and yet the failure rate of the relay itself is much smaller than the rest of the circuit.
As option, 16A single pole relays can be used. but this turns each speaker protection circuit board into single channel. for 150-200W at 8R the actual relays are enough.
The CxD300-8R board size is just 35x95mm. you can install 6 modules one next to the other on two rows, with few mm space between them for a minimum air flow, this will give an overall size of approx. 250x200mm for all the amplifier modules, then the power supply can be installed next to the amplifier modules, having the size of 120x200mm, will fit into a standard rack unit case or even smaller. Mounting holes for the amplifier modules are already isolated from GND to avoid GND loops and the wiring for power supply and signal input is straight-forward. The CxD300-8R comes with connector and cable for the signal input and 2 pcs terminal block for the power and speaker output module.

In fact, ALL the modules which We sell come either with matched connector, cable, plug, terminal block, or whatever is needed for installing without the user need to search or purchase separately any of these cables. Perhaps I must clearly state this for every product. My mistake is that I don't state very clear this aspect, but I believe that the feeling on the user side is better than what he feels when he order from other vendors which state that they provide interconnection sometimes as a "gift" but often "forget" to send it.

noah katz 23rd September 2012 12:19 AM

With 50VDC PS my speakers will draw 8A, and combined with the inductive effect, leaves me a bit worried.

I'll look for some protectors with bigger relays.

I wanted to line up all of the modules along the back of the case to keep input and speaker wiring shorter, but I guess it's not that important.

I'm glad to hear that connectors are included, that makes it a lot easier.


Cristi 23rd September 2012 03:15 PM

Unless you gonna use the amplifier and the speaker to listen sine waves or square waves, I see no reason to worry about the current rating of the relay. With a crest factor of 1/8, and max. 1/3 of music, that 8A are in fact 1A average or 2.66A max. average.

The modules can be arranged all in line as well, but the overall width will be around 45 to 48cm, if they are spaced 2-4 mm. The boards are built in panels of 2 identical modules, with the size of 74.5x95mm, and they are cutted to individual modules after assembly. If you want I can provide uncutted boards, so you can install them more easily.

noah katz 23rd September 2012 09:59 PM

The concern isn't the operating current, in case of amp module failure that would put PS voltage directly to the speaker.

The case internal width is 430 mm, not enough for 6 x 74.5, but I'll keep that in mind for layout studies.

Is it OK for the heat sinks of adjacent modules to touch each other?

noah katz 24th September 2012 05:37 AM

3 Attachment(s)

You didn't say anything about an explicit wiring diagram, so I suppose I have to guess.

Are the connections correctly labeled in the below picture?

What is Mu...?

Does any part of the module or SMPS get connected to chassis ground?

Cristi 24th September 2012 05:57 PM

The connections are fairy simple, same as you indicate in the picture above, there are two connectors only, one have 5 pins, Speaker output, GND, V-, GND, V+ and the other connector has 3 pins, Input, GND and Mute. by default the amplifier is set to operate mode, and connecting the Mute pin to GND will mute the amp. The mute to operate has a delay of ~ one second, to allow the amplifier to operate normally without any click-pop noise.

noah katz 25th September 2012 04:27 AM


The description of the CxD250-HP says it has "audiophile sound quality", which it doesn't say in the descriptions of the CxD300-8R.

Does it really sound better?

If so then I might consider using three of the CxD250-HP for the front speakers.

Can you (or anyone) say how the sound of your modules compares to any of the Hypex ones?

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