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Low effort Class D with ready made modules

Posted 5th April 2011 at 04:45 PM by alexcp (My DIY projects)
Updated 6th April 2011 at 01:29 PM by alexcp

To try out Class D without working too much, I picked two ready-made Class D amplifier modules: one is the $45 2*100 Watt Class-D Audio Amplifier Board from Sure Electronics with the optional $10 volume control board, the other is the $199 IRAUDAMP7S from International Rectifier.

The Sure Electronics module is based on Tripath's TK2050 chipset. Powered from a 150W 24V SMPS from Mean Well, it predictably puts out about 22W RMS to a 8 ohm load. (The declared 2*100W requires a 30V supply and a 4 ohm load.) The sound and the measurements are decidedly mediocre, although at the $45 price, the module still may be a good value. Also, the volume control board feels odd, as the knob only adjusts volume after a push; another push disconnects it again.

The IRF module requires dual rail supply, for which I chose an SMPS400A180 by hypex. With +/-40V rails, the amplifier delivers 100W RMS into a 8 ohm load. The measurements are good, and the sound is very interesting for...
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Old

I need Help im trying to build a leslie speaker

Posted 4th April 2011 at 10:58 AM by ZWade

im trying to build a leslie from mix and match parts so far ive got the speakers amps and crossover kits. im having trouble with what im going to do with the motors. does any one have any information on how to build alternative leslie speakers. i'm a beginner to build these types of things so the simpler the better.
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Emitter resistors and diamond buffers and distortion

Posted 3rd April 2011 at 03:36 PM by rjm (RJM Audio Blog)

Plenty of helpful advice in response to my question on emitter resistors, here.

And so finally I finish my prototype Sapphire amplifier, pictured below. The case is from Chinese audio outfit hlly, and very good. I bought it on eBay.

The rest of the components are described on my web page.
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Sapphire Headphone Amplifier

Posted 28th March 2011 at 02:15 PM by rjm (RJM Audio Blog)

Since I was effectively blogging my progress with the project as a forum thread anyway, perhaps it would be better to make it a blog rather than a post. I'm open to the idea, but does anyone ever read these blogs?
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For Paul

Posted 27th March 2011 at 03:18 PM by klewis

LME 49811 schematic is the one used for the tests with only the 30pf compensation in the circuit.
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On distortion by Bob C

Posted 25th March 2011 at 08:30 PM by klewis

I don't find it hard to believe that very low levels of certain kinds of distortion are detectable when at the same time virtually un-measurable differences between passive elements like cables and capacitors are widely believed to be audible.

THD-20 does not tell the whole story on amplifier behavior, but it has also been given a bad rap because single-number usage of THD-20 can obscure the real story. If you have THD-20 with a full-spectral analysis out to the 7th or 9th harmonic, it tells a lot more, but most THD analyzers start cutting off at 80 kHz. One should always take note of the waveshape of the THD-20 distortion residual as well. If it is rather sinusoidal, that is often not too bad. If it is spikey, that is potentially very bad.

CCIF 19+20KHz with full spectral analysis is much better because the IM products lie in-band.

At the same time, moderate levels of benign THD, like mostly 2nd and 3rd, may not bother anyone very much. This...
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Old

New pair of power amps for the my subs

Posted 19th March 2011 at 08:48 AM by googlyone

In the process of upgrading the subs in the play room. The aim was to deliver in the 1kW region into 8 Ohms. Discretion (and common sense - if that ever entered the equation) led me to shoot for something closer to 650 watts (measued 73vrms, or 666 watts on a sine wave into an 8 ohm load, which brought a wry smile to my face).

I chose to use a bridged configuration, as this allowed the use of supply rails at sensible levels (+/-65V) odd. It also allowed me to use a heap of capacitors that I had laying around.

The transformers are ANTEK units, which much to my disgust cost less to buy and ship from the US than to buy locally made. (Sorry about being parochial, but shipping a two 20lb lumps of steel to Australia is expensive - what is with our local businesses???)

No surprise that I was worried about:
- Power supply - needs to be big
- Cooling - an awful lot of heat to get rid of
- Safety - don't want to be melting my speakers,...
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Old

NAD705

Posted 14th March 2011 at 02:17 AM by damith74

Controller board malfunctioned..
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Old

Blogspot

Posted 13th March 2011 at 12:19 PM by ferynov
Updated 17th March 2011 at 02:25 PM by ferynov (edit)

Diy Woody "grado wanna be" inside driver is KSC75. cheap and sweet sounding.

Click the image to open in full size.
http://hobbyaudios.blogspot.com/2011...teak-wood.html

another my audio blog

http://hobbyaudios.blogspot.com/
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Philips CD 880

Posted 10th March 2011 at 05:12 PM by Ronnmaui

I have a Philips CD 880 which I purchased in the 80's and had it modified by Soloist Audio and have enjoyed the machine all these years, until the last year. It stopped playing CD's altogether. The mechanism would open and it would spin, but no sound or no control. I am not a tech as you can tell. I sent the player to Atlas Audio in Pittsburgh and they claimed they could fix it and they returned it in a month. It worked great for one weekend, then stopped again.
I sent it back to them and they spent another 3 months trying to figure out what to do. They said it was repaired and sent it back to me a second time. In the process of shipping it to me the second time the player got "dented" on the rear of the chassis and when I plugged it in, it did not work at all. I got Fedex involved since they insured it and they sent it back to Atlas and gave them 50% of the insurance money. Again they kept the player a couple more months and could not fix it. They finally returned...
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