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Old 20th August 2010, 11:02 PM   #391
Ryssen is offline Ryssen  Sweden
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Quote:
Originally Posted by Tekko View Post
It's similar to this layout:
Click the image to open in full size.

And its rock solid, the carrier resudial is so clean that one could think it was the output of a function generator, not even the slightest hint of switching noise.
Are there eagle or gerber files to DL for this board?
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Old 20th August 2010, 11:24 PM   #392
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Yes but that is an old design which have been superseeded by a much better performing version.

I will publish the latest design sometime this weekend.
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Old 21st August 2010, 08:07 AM   #393
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Now i have killed back the 300mV dc offset on the output down to -3mV by adding approx 870kOhm between one input and the negative dc rail.

This also aids startup.
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Old 22nd August 2010, 01:09 AM   #394
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Quote:
Originally Posted by Tekko View Post
AP2, i used the enable/disable in the current source like in the philips ucd schematic: http://www.nxp.com/documents/user_manual/UM10155.pdf

pad 3 and 4 in my schematic, tho i guess using the sd pin on the IR2010 would yield similar results, i chose what i chose because i dident feel like digging up the ground plane around the SD pin.
Click the image to open in full size.

And here are two new pics of the updated startup delay:

Amp in standby, no oscillation:
Click the image to open in full size.

Amp active:
Click the image to open in full size.

The white led was supposed to be yellow, picked the wrong bag.
Hi Tekko,
I did not completely read the posts but try these;
i) put an electrolitic cap parallel to R6 for delayed turn on, also disconnecting R2 from gnd can be used as disable function.
ii)Or put an electrolytic cap from vdd to SD pin of IR2112 and let the SD pin go to -24v with a resistor. For both i&ii you need to make some calculation for cap and/or resistor values.
iii)To adjust the offset use offset balance fuction already supplied on LM311 (pins 5,6).

Regards
FH
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Old 22nd August 2010, 06:36 AM   #395
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That wouldent work, i needed a delayed turn on and an instant turn off.
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Old 22nd August 2010, 09:46 AM   #396
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I've now added a buffer to the input:
Click the image to open in full size.
Click the image to open in full size.
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Old 22nd August 2010, 09:48 AM   #397
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Hello Tekko ,
did sound quality improve?
from what do you feed the signal to the amp? differential output source, or plain Cd player?

Regards,
savu
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Old 22nd August 2010, 10:52 AM   #398
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The audio source is my computer, i mix the channels into mono, then run the mono signal through two opamps, one inverting and the other non inverting.

After that the balanced signal travels thround an old ethernet cable to the amp, around 7 meters worth, at the amp its received by the buffer that i chose to have an input impedance of 18kohm.

There might be a slight improvement in audio quality.
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Old 22nd August 2010, 10:55 AM   #399
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balanced lines are great .. you can expand even further than 7 meters ...
try to use shielded Ethernet cable.. or even better shielded microphone cable to be on the safe side with parasitic pick-up.
regards,
savu
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Old 22nd August 2010, 11:12 AM   #400
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I have a reel of twisted cable with a shield braid around it, but its at my old adress. The 7 meter tp cable was what i had at hand.
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