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Class D Switching Power Amplifiers and Power D/A conversion

200W IRS2092 Amp for
200W IRS2092 Amp for
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Old 18th June 2015, 12:36 AM   #21
xrk971 is online now xrk971  United States
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200W IRS2092 Amp for
Quote:
Originally Posted by abraxalito View Post
Yet I can't see any opamps on that board - admittedly the heatsink's covering a large area and there could be one under it. Equally no sign of supply regulators for an opamp. Without an opamp or some kind of input buffer, the input impedance has to be that of the IRS2092 chip's application circuit.
There is no op amp under the heatsink that I can see from peering underneath with a flashlight. Are you saying that it is internal to the 2092 and is behind an input cap and probably a value of 3.2k? Why have a 100k resistor on the input then? Just to drain things? Once I get the proper +/-52v power supply I will test it and compare signal out vs v input.
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Old 18th June 2015, 12:41 AM   #22
abraxalito is offline abraxalito  United Kingdom
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There's an 'OTA' (like an opamp but with a current output) inside the IRS2092 and that's being operated just like an opamp in inverting mode. With an inverting mode opamp the input impedance is determined by the input resistor - that's normally 3k3, there's also a cap in series with this to give roll off at LF.

So yeah I rather suspect the 100k you measured is a drain resistor for the input coupling cap.

Assuming that the impedance is as shown in the application circuits (3k3) then those using an opamp to drive it will probably benefit subjectively from biassing their opamp into classA with a current source on the output. Or using a discrete classA buffer.
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Old 18th June 2015, 12:51 AM   #23
nigelwright7557 is offline nigelwright7557  United Kingdom
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Originally Posted by xrk971 View Post

Very nicely made, appear to be quality components-10f-8424-rs225-8-fast-ref-monitor-irs2092-monoblocks.jpg
You cant tell by looking if components are quality or not.
A lot of fakes look just like originals.

The only way to get quality is to buy from top quality vendors.
Forget ebay and Chinese sources and buy from RS and Farnell.
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Old 18th June 2015, 12:54 AM   #24
abraxalito is offline abraxalito  United Kingdom
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The only way? Nonsense.
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Old 18th June 2015, 01:03 AM   #25
nigelwright7557 is offline nigelwright7557  United Kingdom
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I have lost count of the threads on here from people who have been sold fake components.
Then there are those who bought from China, ebay etc and find their amps blow up after a short period of time due to poor quality components.
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Old 18th June 2015, 01:11 AM   #26
abraxalito is offline abraxalito  United Kingdom
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Here though we're talking about a built up PCB, not components. So do RS and Farnell sell stuffed, working classD amps?

It would be useful given that you mention amps blowing up due to poor components to have links to those instances so we can all see the details - then we may get an idea of vendors to avoid, and which failed parts to pre-emptively swap out.
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Old 18th June 2015, 01:17 AM   #27
nigelwright7557 is offline nigelwright7557  United Kingdom
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The same goes for built up pcb's.

I am not going to search for you, you should have done that before you bought the amplifier. Do a search yourself, you will be shocked at how many blow up.
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Old 18th June 2015, 01:23 AM   #28
abraxalito is offline abraxalito  United Kingdom
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Quote:
Originally Posted by nigelwright7557 View Post
you should have done that before you bought the amplifier.
Now you're telling me I've already bought one?
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Old 18th June 2015, 01:33 AM   #29
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Buy cheap buy twice !
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Old 18th June 2015, 01:41 AM   #30
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200W IRS2092 Amp for
wonder how it and the ps compare to a nu1000? (I'd trust the little XLS moreso than the inuke) Behringer iNuke NU1000 Amp Amplifier Fan Swap How To w/ PICS - Page 12 - Home Theater Forum and Systems - HomeTheaterShack.com

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