DIY Class D Multichannel Amplifier

[alto]

I'm toying with the idea of building my own multichannel class D power amplifier as retail offerings I'm finding are not a great fit, or very expensive.
What I'm looking for is basically a power amp to drive the channels listed below with suitable power for the different needs, in one box.
I recently came to think of using ICEpower modules for the whole thing, previously I've been looking at Purifi class D modules, and I have a couple of mono blocks with 1ET400A's, but they are far more expensive than ICEpower when looking at this larger number of channels to drive.

Here is the breakdown, a total of 8 channels at a minimum:

• Front L/R - ICEpower 700AS2, 2 x 350W @ 8Ω
• Center - ICEpower 200AS2, 2 x ~200W @ 8Ω
• Surround L/R - ICEpower 200AS2, 2 x ~200W @ 8Ω
• Rear Surround L/R - ICEpower 200AS2, 2 x ~200W @ 8Ω
• Subwoofers - ICEpower 1200AS2, 2 x ~1200W @ 3Ω

So my thinking is to get a case large enough to house all these modules together, which all have integrated power supplies. The speakers are by Ino Audio and are going to be 2 speakers or more per Surround L/R and Rear Surround L/R, where they should land around 4-8Ω when in parallel, depending on how many. In addition to that the most special thing about this is the number of subwoofers which will be 6 in total (possibly even 8), driven by the 1200AS2 to give roughly 1200W/ch into 3ohm which is where parallel wiring the 3 x 9Ω elements will end up, this should average to 400W/woofer which is more than plenty. Of course if the subwoofers end up being 8 in total I would need more channels as I would end up with a 2.25Ω load with 4 in parallel, which is too much for the 1200AS2.

I naturally have some questions about this as well;

• Are the ICEpower modules good enough for the non-subwoofer channels, I've seen varying comments on how they've not been the best in the past, but I've also seen it stated that their newest range is actually very good?
• Should I consider some other modules as well, I've looked around but found that the ICEpower ones are nice since I can get them one by one with integrated PSUs as well. This means that I don't have to get all the modules immediately and can instead expand the number of modules as I go.
• Where would I be able to find a case suitable for this (I'm in the EU)? I would want to keep it as compact as possible, but can compromise to fit extra fans etc in there if needed. I'm also considering the possibility to 3D print brackets for the amp modules internally so that they can be installed vertically to save on space.

 

[Sokel]

Not a good idea at all to house all the modules together.
1200as2 specially need ample cooling if you're about to push them down to 3 Ohm for subs

The good news is that for the low power channels you can use 300/400a2 modules hooked directly at 700as2 or 1200as2 so you get a lot of PSUs and heat less.

So for the breakdown:
1200as2 x 2
700as2 x 2
300/400a2 x 2 (each one hooked to each 700as2)

That's 12 channels there to mix and match.

Soundimports are official and reliable resellers.

About cases, here, even custom ones:

Modushop by HiFi2000

Specializzati in produzioni di hifi, case per computer e fresatura su frontali. Dal 1977 la ditta HIFI2000 si occupa principalmente della progettazione e realizzazione di contenitori per l'elettronica con un alto grado di finitura

modushop.biz

 

[MaxwellsEq]

I'm toying with the idea of building my own multichannel class D power amplifier as retail offerings I'm finding are not a great fit, or very expensive.
What I'm looking for is basically a power amp to drive the channels listed below with suitable power for the different needs, in one box.
I recently came to think of using ICEpower modules for the whole thing, previously I've been looking at Purifi class D modules, and I have a couple of mono blocks with 1ET400A's, but they are far more expensive than ICEpower when looking at this larger number of channels to drive.

Here is the breakdown, a total of 8 channels at a minimum:

• Front L/R - ICEpower 700AS2, 2 x 350W @ 8Ω
• Center - ICEpower 200AS2, 2 x ~200W @ 8Ω
• Surround L/R - ICEpower 200AS2, 2 x ~200W @ 8Ω
• Rear Surround L/R - ICEpower 200AS2, 2 x ~200W @ 8Ω
• Subwoofers - ICEpower 1200AS2, 2 x ~1200W @ 3Ω

So my thinking is to get a case large enough to house all these modules together, which all have integrated power supplies. The speakers are by Ino Audio and are going to be 2 speakers or more per Surround L/R and Rear Surround L/R, where they should land around 4-8Ω when in parallel, depending on how many. In addition to that the most special thing about this is the number of subwoofers which will be 6 in total (possibly even 8), driven by the 1200AS2 to give roughly 1200W/ch into 3ohm which is where parallel wiring the 3 x 9Ω elements will end up, this should average to 400W/woofer which is more than plenty. Of course if the subwoofers end up being 8 in total I would need more channels as I would end up with a 2.25Ω load with 4 in parallel, which is too much for the 1200AS2.

I naturally have some questions about this as well;

• Are the ICEpower modules good enough for the non-subwoofer channels, I've seen varying comments on how they've not been the best in the past, but I've also seen it stated that their newest range is actually very good?
• Should I consider some other modules as well, I've looked around but found that the ICEpower ones are nice since I can get them one by one with integrated PSUs as well. This means that I don't have to get all the modules immediately and can instead expand the number of modules as I go.
• Where would I be able to find a case suitable for this (I'm in the EU)? I would want to keep it as compact as possible, but can compromise to fit extra fans etc in there if needed. I'm also considering the possibility to 3D print brackets for the amp modules internally so that they can be installed vertically to save on space.

What will be the total peak mains electricity wattage of the box as a whole? What will be the peak mains electricity current entering the box as a whole?

 

[antcollinet]

Sound quality wise, they will be fine.


You need to worry about how you are going to get heat away from the sub units. There'll need to be a beefy heatsink attached to the heat transfer plates, preferably part of the outside wall of the case, so you don't dump all that heat inside the case.

Do you already have the passive subs. If not, I'd consider only using powered subs, and leave the sub amps out - alternatively integrate the sub amps into the passive subs you already have. In the worst case, and since you can 3d print, it should be viable to make an enclosure with an integrated a heatsink, that you can fix to the back of the sub.

Similarly - for the other units, it is not going to be feasible to heatsink them all to your enclosure. That means all heat losses are going inside your enclosure. You will almost certainly need fans to get that out. Integrating silent fans (large/slow) will need to be considered.

I'm not sure "compact" is going to be an option for you with 8 high power channels with a combined (amp + PSU) efficiency in the order of 70%. Even allowing for 10dB headroom, means your "designed for" average power needs to be at least as high as 400W - dumping 170W into the enclosure. Another argument in favour of leaving the Sub amps with the Subs.

 

[Sokel]

The only way I can think that you can get good thermal behavior plus enough current from your grid is dividing them to two cases. at least.

Each case with a 1200as2 (at the one side, heatshinked) and with 700as2 and 300a2 (later is tiny) on the other side, also heatshinked.
Active cooling, low RPM fan on top of that will work its miracles.

Strangely, the two 1200as2 I use as monos combined with two 300a2 are warmer at idle than playing at high levels (and I mean high) .
They do consume 30W each at idle after all.

 

[101geo]

I'm going down a similar route, 1 x 1200AS2 + 1 x 300A2 per case for 2 x 4 channel amps with a noctua NF-A9 92mm fan per case.

 

[alto]

Not a good idea at all to house all the modules together.
1200as2 specially need ample cooling if you're about to push them down to 3 Ohm for subs

The good news is that for the low power channels you can use 300/400a2 modules hooked directly at 700as2 or 1200as2 so you get a lot of PSUs and heat less.

So for the breakdown:
1200as2 x 2
700as2 x 2
300/400a2 x 2 (each one hooked to each 700as2)

That's 12 channels there to mix and match.

Soundimports are official and reliable resellers.

About cases, here, even custom ones:

Modushop by HiFi2000

Specializzati in produzioni di hifi, case per computer e fresatura su frontali. Dal 1977 la ditta HIFI2000 si occupa principalmente della progettazione e realizzazione di contenitori per l'elettronica con un alto grado di finitura

modushop.biz

Ah okay, so you're saying I can use the 700AS2 as shared PSUs for the 300/400A2 modules? I didn't realize you could do that, that's neat.
Definitely also checking that site for cases, thanks for the link.

What will be the total peak mains electricity wattage of the box as a whole? What will be the peak mains electricity current entering the box as a whole?

I'm not entirely sure to be honest, even though the max power output is very high when adding up all the modules I think the actual draw by the system is far less, but I'll have to go through and check this again.

Sound quality wise, they will be fine.


You need to worry about how you are going to get heat away from the sub units. There'll need to be a beefy heatsink attached to the heat transfer plates, preferably part of the outside wall of the case, so you don't dump all that heat inside the case.

Do you already have the passive subs. If not, I'd consider only using powered subs, and leave the sub amps out - alternatively integrate the sub amps into the passive subs you already have. In the worst case, and since you can 3d print, it should be viable to make an enclosure with an integrated a heatsink, that you can fix to the back of the sub.

Similarly - for the other units, it is not going to be feasible to heatsink them all to your enclosure. That means all heat losses are going inside your enclosure. You will almost certainly need fans to get that out. Integrating silent fans (large/slow) will need to be considered.

I'm not sure "compact" is going to be an option for you with 8 high power channels with a combined (amp + PSU) efficiency in the order of 70%. Even allowing for 10dB headroom, means your "designed for" average power needs to be at least as high as 400W - dumping 170W into the enclosure. Another argument in favour of leaving the Sub amps with the Subs.

I will not be going with active subs, the passive subs in question are matched to both the front and surround speaker of the system, I won't be deviating from this.
So if that's a problem with the amp setup then I'll simply have to rethink the approach. As for "compact" lets call it pretty loose, as I said I will compromise on this if airflow etc is required, I'm not expecting that this is possible to build in the size of an egg carton

The only way I can think that you can get good thermal behavior plus enough current from your grid is dividing them to two cases. at least.

Each case with a 1200as2 (at the one side, heatshinked) and with 700as2 and 300a2 (later is tiny) on the other side, also heatshinked.
Active cooling, low RPM fan on top of that will work its miracles.

Strangely, the two 1200as2 I use as monos combined with two 300a2 are warmer at idle than playing at high levels (and I mean high) .
They do consume 30W each at idle after all.

This is good input, I wasn't sure how much heat the modules actually would give off. It's a pretty funny property of the class D modules that they can be warmer at idle than when active for sure, I'm thinking of adding and Audiophonics 12V trigger adapter to the C13 power cable unless it's possible to add that as an integrated component in the amplifier case itself somehow.

I was also thinking loosely about the feasibility of building this amp or amps into a PC case, if it would be possible to find a suitable looking one they often have good cooling solutions with fan mounts in the front. But I'm not convinced that's the way to go at all, it was just a thought, might be quite difficult to find something with discrete looks.

 

[alto]

I'm going down a similar route, 1 x 1200AS2 + 1 x 300A2 per case for 2 x 4 channel amps with a noctua NF-A9 92mm fan per case.

Have you found a suitable case for your project?

 

[alto]

The only way I can think that you can get good thermal behavior plus enough current from your grid is dividing them to two cases. at least.

Each case with a 1200as2 (at the one side, heatshinked) and with 700as2 and 300a2 (later is tiny) on the other side, also heatshinked.
Active cooling, low RPM fan on top of that will work its miracles.

Strangely, the two 1200as2 I use as monos combined with two 300a2 are warmer at idle than playing at high levels (and I mean high) .
They do consume 30W each at idle after all.

I just looked further into this, so you're suggesting 2x 1200AS2, which is different from my original approach of having only one module and drive 3 subs per channel with it. Is it possible to bridge 1200AS2 to get it to behave as a mono block? Because otherwise I seem to be ending up with more high power channels than I need unless I would end up with 8 subs - in which case I would drive 2 subs each with the 4 available channels. I could take this as a sign that 8 subs are a must

I also looked at the cases at modushop, something like the Mini Dissipante looks pretty nice, there is also the larger Dissipante, but I'm not sure if that makes much difference if the modules are all using the case as a heat sink anyway. Speaking of that, when mounting the modules in a case like this to get the case to act as a heatsink, am I correct to assume that it's the base plate that is the heat conductor that you attach to the inside of the case?

 

[Sokel]

I'm going down a similar route, 1 x 1200AS2 + 1 x 300A2 per case for 2 x 4 channel amps with a noctua NF-A9 92mm fan per case.

If the case is properly heatshinked you won't need the fans, i have them exactly like that for 6 years with no problem at all.
300a2 especially is either crazy efficient or my mid/highs are an easy load, they are barely warm at (even hard) use.

 

[Nisbeth]

This is good input, I wasn't sure how much heat the modules actually would give off.

It's in the datasheets for the ICEpower modules. There's an idle consumption figure for the amps (per channel) and one for the SMPS. Add together for total and assume that all the power is dissipated through the heat sinks (which of course it isn't, but then you have a worst-case figure).

 

[101geo]

Have you found a suitable case for your project?

Yes. I'm going for the Ghentaudio D365a-Q1. You can order it drilled for one 300A2 or 400A2 and one 1200AS2 instead of two 1200AS2's. This leaves lots of room for a fan plus filter (The hanger modules really are tiny, 300w/400w p/c from an amp slightly bigger than a playing card!) in the bottom plate which is 5mm thick adding to the heatsink capabilities of the case. The front panel is plain which leaves plenty of room for warning LED's and even small VU meters which I'm considering.

 

[Sokel]

I just looked further into this, so you're suggesting 2x 1200AS2, which is different from my original approach of having only one module and drive 3 subs per channel with it. Is it possible to bridge 1200AS2 to get it to behave as a mono block? Because otherwise I seem to be ending up with more high power channels than I need unless I would end up with 8 subs - in which case I would drive 2 subs each with the 4 available channels. I could take this as a sign that 8 subs are a must

I also looked at the cases at modushop, something like the Mini Dissipante looks pretty nice, there is also the larger Dissipante, but I'm not sure if that makes much difference if the modules are all using the case as a heat sink anyway. Speaking of that, when mounting the modules in a case like this to get the case to act as a heatsink, am I correct to assume that it's the base plate that is the heat conductor that you attach to the inside of the case?

1200a2 is not bridgeable (300/400a2 is), in fact you have to take care to keep its output far from grounding, they are balanced and already bridged.
But you can surely use them as monos (as I do) with zero modification and they output the combined 2 chan power this way.

Also, you won't need extra trigger, they have one onboard along with signalSense (it fires up with signal and shuts off after 13 min without signal) .
They also have a gazzillion of controls and indicators (the later you can combine at a multicolor led, just ask and I'll tell you how) , even analog (scaled) outputs for voltage, temp and current report.

 

[101geo]

the later you can combine at a multicolor led,

Interested in this part, any more details please?

 

[alto]

Each case with a 1200as2 (at the one side, heatshinked) and with 700as2 and 300a2 (later is tiny) on the other side, also heatshinked.
Active cooling, low RPM fan on top of that will work its miracles.

Strangely, the two 1200as2 I use as monos combined with two 300a2 are warmer at idle than playing at high levels (and I mean high) .
They do consume 30W each at idle after all.

Do you have the 1200AS mounted horizontally or vertically in your case? I'm trying to get an image of how they need to be installed in the case (if they can be properly heatsinked when mounted horizontally).

 

[Sokel]

Interested in this part, any more details please?

Sure, is very easy to do.
You just use a multicolor led with common anode,the 5V PS (P102 connector, pin 11 if I remember right, check it out for sure) will go on the + (LED's common anode) and all the others indicator pins to each color leg.

Edit: To regulate LED's brightness use the resistors (100-200 Ohm normally) at each indicator's leg, so for four indicators for example (ON, clip, temp, standby, whatever) you use four resistors.

 

[Sokel]

Do you have the 1200AS mounted horizontally or vertically in your case? I'm trying to get an image of how they need to be installed in the case (if they can be properly heatsinked when mounted horizontally).

I have it mounted directly to the heatshink, module at its side.
You can of course do the same by mounting it horizontally with an angled (so to reach heatshink) heat transfer capable metal, like copper, so to have it laying down the case.
Both work.

 

[alto]

Okay so I've thought about things a bit more, toying with ideas a bit.

I've been looking a bit at this case from Audiophonics (this might well be the same as from modushop), and whether or not it would be feasible to fill it with

• ICEpower 1200AS2 for subs
• Purifi Eigentakt EVAL3 Mono 1ET7040SA for front speaker
• ICEpower 700AS2 + 3/400A for surrounds

The above is kind of silly for the surrounds, I feel like I would have wanted a 300AS2 + 300A, that would probably be enough power, but not ridiculously overkill. I think I will end up with 2 surround speakers on each channel, resulting in an 8ohm load.

But in any case I'm wondering if this would make sense, the lower case would require all the amp modules to be mounted horizontally on the bottom of the case, and the Purifi module would need a PSU added as well. I have two Purifi 1ET400 mono blocks since before and they sound great to me, not sure if the ICEpower modules are as good for front speakers. I would probably be able to mount an 80mm fan in the back of the case if needed, and run it on low rpms just to get some airflow through the vents at the top and out the back.

 

[101geo]

Okay so I've thought about things a bit more, toying with ideas a bit.

I've been looking a bit at this case from Audiophonics (this might well be the same as from modushop), and whether or not it would be feasible to fill it with

• ICEpower 1200AS2 for subs
• Purifi Eigentakt EVAL3 Mono 1ET7040SA for front speaker
• ICEpower 700AS2 + 3/400A for surrounds

The above is kind of silly for the surrounds, I feel like I would have wanted a 300AS2 + 300A, that would probably be enough power, but not ridiculously overkill. I think I will end up with 2 surround speakers on each channel, resulting in an 8ohm load.

But in any case I'm wondering if this would make sense, the lower case would require all the amp modules to be mounted horizontally on the bottom of the case, and the Purifi module would need a PSU added as well. I have two Purifi 1ET400 mono blocks since before and they sound great to me, not sure if the ICEpower modules are as good for front speakers. I would probably be able to mount an 80mm fan in the back of the case if needed, and run it on low rpms just to get some airflow through the vents at the top and out the back.

No point getting a case with side heatsinks if you are going to mount the 1200AS2 on the base, that one is not tall enough for the 100mm module, If you want that style of case you should get the 3U and mount the 1200AS2 on one of the heatsinks vertically. The Purifi module also needs a power supply pushing the cost of that channel close to 1000 euro. Definitely not worth 3 times the price of the stereo 1200 when you won't hear any difference. Last point, having all those modules in one case is going to lead to heat problems without active cooling.

 

[Nisbeth]

IIRC there is also a limit on how many ICEpower supplies you can put in the same case and stay within touch current limits. If you want 10 channels I'd find a way to distribute that across 2-3 cases - will give some flexibility as well.