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Class D Switching Power Amplifiers and Power D/A conversion

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Old 30th April 2009, 11:34 AM   #41
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Hi Cirrus18,

I haven't got a copy of the wiring diagram - I'll ask Class-D for one today.

I'll do my best to try the amps 'as supplied' before tweaking - you are absolutely right that this would provide the most meaningful report.

You're right that the input coupling cap protects the amp from DC on the input, but I think the one on the board is ceramic and it can easily be bypassed by connecting the input wire to the far side of C6 rather than the designated input point. My UCD amps have Russian FT-3 fluoroplast caps at the input. Given the lower input impedance of the class-d amp (12Kohm vs. 100Kohm) I won't be able to use the same value of caps, so I'll either use some HUGE 4.7uF Russian teflon caps or a couple of 3.3uF Epcos MKV.

In my experience upgrading the PSU caps is always worthwhile. It's also really easy and really cheap to do, so I'd consider it an obvious tweak for anyone who can assemble an amp. The Rubycon ZLH caps worked very well in my modded Behringer SRC2496, and are readily available from Farnell in the UK - I ordered them at the same time I ordered the chassis connectors etc. The main PSU will be a 330VA 2x41V transformer, 35A 400V rectifier bridge and either 2 or 4 BHC slit foil 10000uF 80V caps per rail (depending on what I can fit in the case!). I'll bypass the diodes in the rectifier with 0.1uF Russian polystyrol caps.

Hopefully I'll get into the build on Saturday :-)
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Old 30th April 2009, 12:34 PM   #42
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Default Wiring Details

Hi James,

I have sent you the pdf document in an e-mail. For anyone else interested in the wiring details, please see... Details.pdf

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Old 30th April 2009, 01:28 PM   #43
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Exclamation Something fishy

The distortion figures in the datasheet seems fishy. Decreasing distortion at higher frequencies? Besides: No conditions given either. 0.002% distortion at 20kHz is not just right, my gut feeling.
/Per-Anders (my first name) or P-A as my friends call me
PA03 LM4780 amplifier group buy, SIGN UP HERE for the group buy 0 boards left. 118 paid.
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Old 30th April 2009, 01:50 PM   #44
No instructions no info, this making seem stolen was not it. What worse more bias not adjusted? Telling me now module not even tested. With solder problem known already it bad quality and no control. Worse and worse more time go more worser get.

For input cap being ceramic that can to explainetion immediat your saying more detail and presance weren't it? It call piezo effect, it noise modulate you know? this opinion meaning less when finding you prefering noise. No audio people for right mind lissen with ceramic for sizing need for input copuling because it mean a piezo type.

Thinking cirrus maybe you just want sound to better for saying so look what seeing I have it gooder and cheaper and in mind you think true but it sound more and more you got what pay for. You listen to ceramic for more of 10 minute at time before ears constipate cireously?

You right perandy it lying in measure because it use AES17 class d measuring filter so it only good for read to 7khz maybe and after it all atten for havin no harmonic at all. Maybe nice admin can move these postings to AVB where it belong this no class b support forum and it rude to people hear.
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Old 30th April 2009, 03:06 PM   #45
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Originally posted by sharpi31
Hi Cirrus18,

my modded Behringer SRC2496,

Hi sharpi31,

I'm very interested to hear that you have the SRC2496 crossover. I bought six of the nx 200 modules to use in an active three-way speaker system using a cx3400 for a crossover. I finished it this week but was disappointed to hear how much hiss the cx 3400 produced. The unit also had a fault where one mid channel had very low output. So it's gone back for a refund.

I am thinking of getting now the SRC2496 which is digital as you know. How do you find yours? Any hiss? And would you recommend it as an audiophile quality unit? Before any modifications that is.
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Old 30th April 2009, 03:53 PM   #46
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look the same
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Old 30th April 2009, 03:55 PM   #47
bwaslo is offline bwaslo  United States
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Originally posted by cirrus18
.... they said the the best way of adjusting the bias was using an oscilloscope and signal generator and set up for a minimum crossover distortion.
Are you sure that's the whole setup? It seems that if the crossover distortion were enough to be seen on a scope it would have to be very high (negative feedback should reduce it well below visibility. Or is this a no-feedback design?). Could it have been that the distortion was supposed to be viewed on the residual (applied frequency notched out) from a distortion analyzer?
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Old 30th April 2009, 04:07 PM   #48
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I'm very interested to hear that you have the SRC2496 crossover
The SRC2496 is a dac/adc/sample rate converter. I think the unit you need is the DCX2496 - the digital active crossover.

I think all of the Benringer ***2496 range can be modded so that the active output stage is bypassed and replaced with a single transformer per channel. I did this using a pair of Sowter 3603 transformers. I also replaced the PSU caps with Rubycon ZLH and all small electrolytics (except the analog input coupling caps - i don't use the analog ins) with solid polymer caps. All in all an excellent dac :-)
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Old 30th April 2009, 04:44 PM   #49
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Cirrus: keep on topic - no insulting posts!
You could see they had different IP!

Off topic post deleted
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Old 2nd May 2009, 09:43 AM   #50
Havoc08 is offline Havoc08  Denmark
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Originally posted by nicoch46
look the same
If memory serves from other thread that aussie amp is the real deal. Higher quality, realistic specs etc.
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