2x250 IRS2092 amp build

[neildavis]

Re: 2x250 IRS2092 amp build

Pete,

With independent secondaries, wouldn't you want to do this instead of tying them in series (please see enclosed drawing)? I think you would preserve the current of each secondary pair for each channel. Thanks.

Pete's approach is the most common configuration, used in many, many amplifiers. However, there are some claims that the dual rectifier approach will reduce noise due to saturation currents in the transformer (see this link). Either solution will work, but there may be some cases where the dual rectifier approach is advantageous. Pass later explains that:

As I said, this is only an issue when there is an imbalance of windings and net DC current, which is not a typical situation.

This situation should not be an issue for this amplifier and these transformers, so I'd second Pete's recommendation to use the simpler approach (unless, of course, you already have a working dual rectifier solution .)

[hongrn]

Re: 2x250 IRS2092 amp build

Pete, Neil, thanks so much guys. This has been an exciting learning session. Just when you think you got it finally, you ain't got it. Ben, Wolfie, thanks for your timely input.

Hong

[Pete Schumacher]

Re: 2x250 IRS2092 amp build

Pete,

With independent secondaries, wouldn't you want to do this instead of tying them in series (please see enclosed drawing)? I think you would preserve the current of each secondary pair for each channel. Thanks.

That will work because both supplies are floating. The previously linked PDF had a ground running from the caps of the individual sections which was quite odd.

[[email protected]]

Re: 2x250 IRS2092 amp build

I'm more confused then ever!

http://sound.westhost.com/project04.htm

[neildavis]

Re: 2x250 IRS2092 amp build

I'm more confused then ever!
http://sound.westhost.com/project04.htm

Project04 is a solution for a different problem. It uses separate filters/reservoirs for each channel to keep interaction between left and right channels to a minimum. That only works when you have separate power connections to each amp. However, the 2x250 board uses a shared power supply connection, so project04 is not relevant.

[Wolf]

Re: 2x250 IRS2092 amp build

Ben, Wolfie, thanks for your timely input.

Hong

No problem! Just noticed I did not see what was stated is all.
Later,
Wolf

[[email protected]]

Re: 2x250 IRS2092 amp build

I get it now. There are indeed series caps in parallel. Thank you.

[hongrn]

Re: 2x250 IRS2092 amp build

Neil, Pete, and Everyone,

This is the TI power supply schematic that I use for all my builds. As you suggested in the above post, the secondaries are wired in series with a center tap, then connected to bridge rectifier. This design calls for 2 reservoir caps of 20,000uF each per rail, wired in series, then in parallel with 2 more. Electrically, you would end up with 20,000uF per rail, wouldn't you? Here's the excerpt from the TI Application Note AN-1849:

"CS3, CS4 are the large reservoir capacitors to supply large current demands and stabilize the supply rails to minimize low frequency fluctuations. These are very large value electrolytic capacitors. Two capacitors are used to achieve the desired 40,000μF capacitance per rail."

1. Please explain the math between the physical orientation of these caps, versus their electrical sum.

2. So, if you had 2 PSUs wired this way, or in Don's case, you bought 2 wired this way, how would you combine them to end up with +/Gd/- rails for the Sure IRS2092 board?

Thanks for your clarification.

[PWR RYD]

Re: 2x250 IRS2092 amp build

Hi Hong,

From a physical location standpoint it doesn't make any difference if the traces (or wires) reach the big caps first or second as long as the traces or wire sizes are large enough and short enough not to introduce a lot a stray inductance or resistance. I think that was what you were asking.

The schematic shows the large caps labeled as Cs3A,B and Cs4A,B. It only shows one big cap per rail but the label indicates that there are really two caps per rail. It shows the value as 20,000uF. From my experience that value is indicating that each cap (A and B) are of that value. So the total capacitance per rail would really be 40,000uF.

If you had two PS wired this way but only a single amp board with only a single power supply input terminal block you would just combine (parallel) the two PS at the amps PS input. That's not how it is usually done but it's not wrong.

I am building another Class D amp right now that uses two amp boards each run in bridged mode (one amp board per channel) for 600 wpc into 4 ohms. I have one huge 1000 VA toroid with dual secondaries. I am running them in series with their center point as ground (exactly like Pete showed). But I have two full wave bridge rectifiers fed from these windings and two complete cap banks, one for each channel (amp board). Should be a monster when it's done. I'll post pictures as I build it. Just picked up the walnut board that will become its case.

[hongrn]

Re: 2x250 IRS2092 amp build

Craig,

How can it be 40,000uF if the caps are wired in series? That's what I can't wrap my head around. On your answer about wiring the 2 PSUs in parallel, please take a look at the Sure power connection instructions. Thanks for your help on this. Can't wait to see your build. Can you post a schematic of your PSU?

Hi Hong,

From a physical location standpoint it doesn't make any difference if the traces (or wires) reach the big caps first or second as long as the traces or wire sizes are large enough and short enough not to introduce a lot a stray inductance or resistance. I think that was what you were asking.

The schematic shows the large caps labeled as Cs3A,B and Cs4A,B. It only shows one big cap per rail but the label indicates that there are really two caps per rail. It shows the value as 20,000uF. From my experience that value is indicating that each cap (A and B) are of that value. So the total capacitance per rail would really be 40,000uF.

If you had two PS wired this way but only a single amp board with only a single power supply input terminal block you would just combine (parallel) the two PS at the amps PS input. That's not how it is usually done but it's not wrong.

I am building another Class D amp right now that uses two amp boards each run in bridged mode (one amp board per channel) for 600 wpc into 4 ohms. I have one huge 1000 VA toroid with dual secondaries. I am running them in series with their center point as ground (exactly like Pete showed). But I have two full wave bridge rectifiers fed from these windings and two complete cap banks, one for each channel (amp board). Should be a monster when it's done. I'll post pictures as I build it. Just picked up the walnut board that will become its case.

[robertcottiers]

Re: 2x250 IRS2092 amp build

Hong: I am late to the party here...The TI schematic is confusing you,They should have just shown each rail with 2 caps of the same value for each
rail,it would have been a little less confusing for the less experienced.There are no series capacitors involved in this schematic.


Bob

[PWR RYD]

Re: 2x250 IRS2092 amp build

I agree Bob. When there are a dozen or so caps it makes some sense to show it as one cap referencing how many. But with only two caps???

Hong,
Yes technically if you are looking from +V to -V there are two caps wired in series. But every thing in the electronics world is almost always referenced to common (or ground). In that case there is only one cap (it is actually two 20,000uF in parallel) from the +V rail to ground and one cap from the -V rail to ground.

Wait till you get bit by the vacuum tube bug and you run into lots of old text books that used the old school electron current flow instead of the modern "conventional" current flow. Everything is bass akwards. My electronics teacher in high school was a Vietnam vet radio man. He taught us the old military current (Electrons) flows from ground (negative) to the B+. Took me almost the whole first semester of college to get my brain turned around

[Wolf]

Re: 2x250 IRS2092 amp build

I agree Bob. When there are a dozen or so caps it makes some sense to show it as one cap referencing how many. But with only two caps???

Hong,
Yes technically if you are looking from +V to -V there are two caps wired in series. But every thing in the electronics world is almost always referenced to common (or ground). In that case there is only one cap (it is actually two 20,000uF in parallel) from the +V rail to ground and one cap from the -V rail to ground.

Wait till you get bit by the vacuum tube bug and you run into lots of old text books that used the old school electron current flow instead of the modern "conventional" current flow. Everything is bass akwards. My electronics teacher in high school was a Vietnam vet radio man. He taught us the old military current (Electrons) flows from ground (negative) to the B+. Took me almost the whole first semester of college to get my brain turned around

Because it's DC and electrons are negatively charged.
Wolf

[PWR RYD]

Re: 2x250 IRS2092 amp build

Because it's DC and electrons are negatively charged.
Wolf

Yeah, and?

[[email protected]]

Re: 2x250 IRS2092 amp build

So, What is the conclusion about my PSU?

Its sure sounds good!