2x250 IRS2092 amp build

[hongrn]

Re: 2x250 IRS2092 amp build

Neil,

In this pdf, you wrote "It will work fine, but the middle rows of caps do nothing". I'm not really sure what you meant here, because there's no middle caps, since each rail has only one row of caps. Bottom line, the whole thing has to do with the 2 PSU requirement of the Sure board. I haven't tried it, but I'm tempted to use just one. You built one Sure amp a while back, did you use one or 2 PSUs in your build? Thanks.

I don't think that anyone can make a conclusion about the PSU until they know exactly how it is wired. Hong posted two different PDF files that are different from the "standard" center-tapped transformer with a single bridge rectifier. I'm not clear on how yours is wired, and how the grounds connect together. But I'm guessing that yours is equivalent to the second PDF schematic that Hong posted, which I believe is equivalent to the first one he posted, with 2 of the 4 rows of caps shorted out. The power supply will still work and the amp will sound great, but you aren't getting the full effect from all of those caps, since only half of them are in the circuit. See the attachment for more information. But again, I'm not certain that I understand how your PSU is wired, so I'm making some guesses...

[ATTACH=CONFIG]46993[/ATTACH]

You can verify whether the caps are shorted out with an ohmmeter. If they aren't shorted out, then I'm with Pete--the first circuit that Hong posted is a head-scratcher . You can try following the flow through the diodes, but unless you have a clear idea what else "GD" is connected to, it's a waste of time. If GD isn't connected to ground, then measure the voltage at GD with respect to the ground--that will help us understand the circuit.

[neildavis]

Re: 2x250 IRS2092 amp build

So, What is the conclusion about my PSU?

Its sure sounds good!

I don't think that anyone can make a conclusion about the PSU until they know exactly how it is wired. Hong posted two different PDF files that are different from the "standard" center-tapped transformer with a single bridge rectifier. I'm not clear on how yours is wired, and how the grounds connect together. But I'm guessing that yours is equivalent to the second PDF schematic that Hong posted, which I believe is equivalent to the first one he posted, with 2 of the 4 rows of caps shorted out. The power supply will still work and the amp will sound great, but you aren't getting the full effect from all of those caps, since only half of them are in the circuit. See the attachment for more information. But again, I'm not certain that I understand how your PSU is wired, so I'm making some guesses...

PS.pdf

You can verify whether the caps are shorted out with an ohmmeter. If they aren't shorted out, then I'm with Pete--the first circuit that Hong posted is a head-scratcher . You can try following the flow through the diodes, but unless you have a clear idea what else "GD" is connected to, it's a waste of time. If GD isn't connected to ground, then measure the voltage at GD with respect to the ground--that will help us understand the circuit.

[PWR RYD]

Re: 2x250 IRS2092 amp build

Hi Hong,
What you said is correct. But that technique is rarely used, other than in DIY (because that's what I have to work with). Two 50V caps in series will most always cost more and take up more space than one 100V cap with the equivalent capacitance. Luckily for us DIY guys we can do what we want.

[PWR RYD]

Re: 2x250 IRS2092 amp build

Part of me says "if it sounds good leave it alone". But the other part of me says you already have all the parts so it only takes a little DIY hobby time and some solder to rewire it for the maximum possible capacitance. Will it sound better? Maybe. Will it sound worse? Doubtful.

[robertcottiers]

Re: 2x250 IRS2092 amp build

Lets continue the capacitor discussion with a modified scenario,lets say we have a large amount of 20,000 uf capacitors rated at 50 volts,The original specification called for a 20,000 uf capacitor at a 100 volt rating.

We have the required capacitance value but only half of the required voltage rating,we will need to wire 2 of our capacitors in series to double the voltage handling.We need to take the negative lead of 1 cap and solder to the positive lead of a second cap....nothing will be connected to this junction.This leaves us with two leads a plus and minus. Cover both series connected caps with an imaginary piece of shrink tubing :D. Now take a white marker and write our new value of 10,000 uf 100 volts.

Notice that our 20,000 uf rating is now cut in half,but we now have a 100 volt rating...We will need to make another series connected pair just like the first one...We now take the 2 pairs and connect them in parallel to obtain the final value of 20,000 uf at 100 volts. There are other potential issues with series connected caps but I won't cover them here.Connecting caps in series to obtain a higher working voltage is something you would do in a pinch ;).

I thought an "Over explanation" might help those who still a bit unsure...

Regards
Bob C.

[[email protected]]

Re: 2x250 IRS2092 amp build

So, What is the conclusion about my PSU?

Its sure sounds good!

[PWR RYD]

Re: 2x250 IRS2092 amp build

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

Yeah, and?

[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

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

[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

[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.

[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

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.

[[email protected]]

Re: 2x250 IRS2092 amp build

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

[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