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-   -   New T-Amp measurements (http://www.diyaudio.com/forums/class-d/75286-new-t-amp-measurements.html)

Pano 6th March 2006 12:29 AM

New T-Amp measurements
 
After a lot of time and work the new T-Amp measurements are up on my site. Please have a look.
New Measurements

All these measurements were done by a buddy of mine, who is an amp designer for a very large amplifier company. All measurements were plotted with an Audio Precision tester, the industry standard for audio measurements.

You will notice that these tests are not as pretty nor as good as those you will see from manufacturers. The reason for that is that these are real world tests, done without tweaking the test conditions to make the dives perform for measurement. What you see is what you get. The results are much more likely to match the results you will obtain than "optimized" results published by chip and amp makers.

I hope you enjoy the information. Please feel free to ask questions, I'll do what I can to answer them.

BWRX 6th March 2006 01:14 AM

Beautiful! :up: Any chance you guys could test my board if/when I get a couple prototypes built?

vt4c 6th March 2006 04:09 AM

Nice work!:up: :up:

D0Hbert 6th March 2006 09:48 AM

Just wondering panomaniac, would it be advisable to use a separate SMPS PSU for the amp6, bypass the rectifiers and the volt regulator, then connect the output of the SMPS directly to the big 16,000uf cap? Will this setup somehow improve amp6's score on the S/N ratio test or on the large spikes on the amp's crosstalk? Thanks for the test results, very informative.

Pano 6th March 2006 08:45 PM

Quote:

Originally posted by D0Hbert
Just wondering panomaniac, would it be advisable to use a separate SMPS PSU for the amp6,
You could easily do that, if you wanted to. I was surprised by the 60 Hz spike on the graph, you sure can't hear it. There might have been some induced hum on that test, I don't know. None of the amps tested with SMPS had the hum. But after all, the 60 Hz does come right onto the AMP6 board. But having power regulation that close to the chip also has many advantages.

I am experimenting with using a 15V SMPS in front of the regulator, and running at 13V. Also am trying a 20V SMPS and running the linear regulator at 14.5V. Should at least give stable power!

Quote:

Originally posted by BWRX
Any chance you guys could test my board if/when I get a couple prototypes built?
I think that will be possible. Will check with the guy doing the tests. You get it running, we'll test it! Look forward to seeing/hearing your board.

cpemma 10th March 2006 07:42 PM

Very useful. I'd love to see the frequency plot for a "lightly-modified" Sonic T-amp, ie, the 'stealth' method 2.2uF input caps, replaced 680uF power cap and a decent power supply.

That's about as far as I dare go with smd boards. ;)

Another thing I've not seen addressed in other threads - the Sonic T lift above about 5kHz with 8-ohm speakers - can that be calmed down with something across the speaker terminals? :confused:

BWRX 10th March 2006 09:42 PM

You just need to change the value of the caps in the output filter to alter the frequency response. Tripath recommends using 0.22uF caps for 8ohm loads instead of the 0.47uF that work best with 6ohm loads.

Pano 10th March 2006 10:43 PM

Quote:

Originally posted by cpemma
Very useful. I'd love to see the frequency plot for a "lightly-modified" Sonic T-amp, ie, the 'stealth' method 2.2uF input caps, replaced 680uF power cap and a decent power supply.
I've got it! Will be up on the site very soon. Will let you know. The modded Sonic is still in the plastic case, so noise and crosstalk are similar, but frequncy response is
not.

cpemma 10th March 2006 11:22 PM

Quote:

Originally posted by panomaniac
I've got it!
:knight: :happy1: :cheers: :worship:

morci 12th March 2006 02:52 AM

Quote:

Originally posted by panomaniac


I've got it! Will be up on the site very soon. Will let you know. The modded Sonic is still in the plastic case, so noise and crosstalk are similar, but frequncy response is
not.

I just can't wait to see that.
Are you planning to feed it with the usual 12V? I'd like to see what happens when you raise it up to about 13.8...

Davide.


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