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Old 10th May 2012, 06:07 PM   #221
AndrewT is online now AndrewT  Scotland
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I have max power tested amplifiers using those fuses and find they never blow during testing.
The heating effect of music waveforms can never be as high as a max power test, so the fuses should never blow during normal and silly party operation.

For those reasons the lower value fuses using Quasi's rule may be better for even closer rating of the fuse to the duty.

BTW,
33Vpk into an 8ohm speaker can only be had from a supply around +-38Vdc. You should never build a 4ohm capable chipamp using +-38Vdc supplies.
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Old 10th May 2012, 08:06 PM   #222
hurtz is offline hurtz  Germany
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Quote:
Originally Posted by AndrewT View Post
I have max power tested amplifiers using those fuses and find they never blow during testing.
The heating effect of music waveforms can never be as high as a max power test, so the fuses should never blow during normal and silly party operation.
And I'd never doubt your expertise.

Quote:
Originally Posted by AndrewT View Post
BTW,
33Vpk into an 8ohm speaker can only be had from a supply around +-38Vdc. You should never build a 4ohm capable chipamp using +-38Vdc supplies.
That's the point, I might have missed to mention it, but I only have access to 18-0-18 toroids. So for any impedance pkV will be 25.5V. So rather than calculating with the maximum continuous power rating of the AMP I'd rather start with my pkV and impedance and look at I and P afterwards. This won't protect the AMP (with 162W peak theoretical output) but that's what spike is for anyways. And it won't blow the fuse for any power-peaks.
(I am not trying to argue experience here.)

cheers,
hurtz!
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Old 10th May 2012, 10:28 PM   #223
hurtz is offline hurtz  Germany
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Updated PSU with Fuse holders (microfuses):

PSU+ v2.4
Attached Images
File Type: png PSU v2.4.png (18.1 KB, 423 views)
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Old 12th May 2012, 01:03 AM   #224
hurtz is offline hurtz  Germany
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Attached you will find the PSU++ v1.0 which is intended to be used with a single toroid and 5 AMP boards for surround sound.

Each rail has 8 caps with 4700uF each, 37600uF total.

cheers,
hurtz
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File Type: png PSU++ v1.0.png (28.9 KB, 399 views)
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Old 13th May 2012, 12:36 AM   #225
hurtz is offline hurtz  Germany
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I added 100nF caps accross the diodes to decrease transformer noise and potentiometers in series with the LEDs to manually set brightness.

PSU+ v2.7
PSU++ v1.1

cheers,
hurtz
Attached Images
File Type: png PSU v2.7.png (19.4 KB, 382 views)
File Type: png PSU++ v1.1.png (30.9 KB, 324 views)
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Old 13th May 2012, 09:28 AM   #226
marce is offline marce  United Kingdom
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Why not use copper pours (areas) instead of the serpentine traces.
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Old 13th May 2012, 11:33 AM   #227
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by hurtz View Post
I added 100nF caps across the diodes to decrease transformer noise
Are you sure this is an improvement?
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Old 13th May 2012, 12:41 PM   #228
hurtz is offline hurtz  Germany
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Quote:
Originally Posted by marce View Post
Why not use copper pours (areas) instead of the serpentine traces.
To increase RC-filter characeristics.

Quote:
Originally Posted by AndrewT
Are you sure this is an improvement?
Well I've read about it on esp which so far never disappointed me, and from the wiring they are optional. I hope I can measure a difference...

cheers,
hurtz
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Old 21st May 2012, 02:54 AM   #229
hurtz is offline hurtz  Germany
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Yet one more question about the secondary fuses, we concluded that the two secondary fuses should be ~2/1.6A for 8r0 speakers. But isn't this the calculation for just one speaker/amp?
Yet twice the ampere rating for two speakers does seem a little bit high. Maybe times sqrt(2)? (And sqrt(5) for 5? :-D)

cheers!
hurtz
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Old 8th June 2012, 11:45 PM   #230
hurtz is offline hurtz  Germany
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So here are some news, the latest revisions have been produced and tested. (PSU+ v2.7/AMP v6.3)

In this design the board is fully populated, including Cd with 330pF, and the new 100nF capacitors across the diodes on the PSU+.
Not included is the 47pF capacitor across the rca inputs.

Attached you will find the rmaa test charts, comparing the older [AMP v5.9/PSU+ v2.2] with the new one. Please ignore any stereo-realted data, I only tested one amp with a Y-cable (I had to use rmaa 5.5 which doesn't support mono mode).

I am glad to report that the noise level decreased considerably, also transformer noise was greately reduced and eliminated at 100Hz.

Please note that the tests were made on two different soundcards, where the "old" amp test was taken on an Asus xonar D2X and the "new" amp on a Creative Soundblaster X-fi USB. Hopefully I will be able to retest both amps on the same soundcard soon, then with added baseline of the soundcard.

cheers!
hurtz

P.s.
Please rename the .txt files into .sav to open them with rmaa.
Attached Images
File Type: png freqresp.png (28.0 KB, 213 views)
File Type: png noise.png (51.8 KB, 67 views)
Attached Files
File Type: txt new lm3886.txt (132.8 KB, 33 views)
File Type: txt old lm3886.txt (97.2 KB, 4 views)
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Last edited by hurtz; 8th June 2012 at 11:48 PM.
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