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Old 7th April 2013, 11:31 AM   #841
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by Ryssen View Post
Do you have a schema of it,it would be easier to see.
There's really no need for schematics:

opamp1.jpg

The 2 caps that are close to each other all have one pin that goes to the analogue volume chip, and the other pin is connected to the DAC output stage.

So you really want to bypass the output stages that include nice low-noise mini-melf resistors? Alright alright...
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Old 7th April 2013, 11:50 AM   #842
JLOP is offline JLOP  France
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Quote:
Originally Posted by chaparK View Post
I wouldn't worry too much about sample rate conversion.

I had a look a the application you have used so far, and suggest you just try rePhase (as recommended by a few forum
Hi Nick

On the first point, sorry to bother, but may you explain to the dumbs (;-) why we should not worry ? I think most of DSP do that resampling, but wont some samples get lost as 48 khz frequency is not a multiple of 44.1 ?

Thanks for the nice tutorial with rePhase ! What about phase correction itself ?

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Old 7th April 2013, 12:24 PM   #843
Julf is offline Julf  Europe
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Quote:
Originally Posted by JLOP View Post
wont some samples get lost as 48 khz frequency is not a multiple of 44.1?
No. No samples get lost - all samples get converted. The usual way of doing it is basically the equivalent of first upsampling by a factor of 160 and then downsampling by a factor of 147 (as the ratio between 48 and 44.1 is 160/147). Another way of thinking about it is to imagine the signal first being converted to analog at 44.1 kHz, and then resampled at 48 kHz. None of the samples are the same as the original, but the signal waveform is still the same.
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Old 7th April 2013, 06:57 PM   #844
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Quote:
Originally Posted by chaparK View Post
There's really no need for schematics:

Attachment 341040

The 2 caps that are close to each other all have one pin that goes to the analogue volume chip, and the other pin is connected to the DAC output stage.

So you really want to bypass the output stages that include nice low-noise mini-melf resistors? Alright alright...
Thanks for the fast reply. Looks really promising then. I have a bunch of desoldered OPA627 that I would like to put in a DAC converter sometimes, fex
But decoupling caps? Are they not coupling caps in the signal path to block DC?

Actually the caps would probably be a better way to feed the signal, as you get a nice pad with a round hole in it. The IC socket is not a HQ socket, thus not that good for round pins.

As I have not seen the board and the layout especially , would it be possible to desolder the IC sockets without to much risk of damaging the routing?
I have quite good tools, but anything connected to a big heatsucking copper area is always difficult to desolder (like swollen filter caps on PC motherboards, they are a pain in the donkey to desolder)

Sorry for all the questions, but what post DAC filter topology do you use ? Sallen Key or MFB? I used MFB in my post-DCX2496 differential-single-ended filter to prevent oversampling noise feedthrough @ MHz.
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Last edited by rikkitikkitavi; 7th April 2013 at 07:02 PM.
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Old 8th April 2013, 02:04 AM   #845
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by rikkitikkitavi View Post
Thanks for the fast reply. Looks really promising then. I have a bunch of desoldered OPA627 that I would like to put in a DAC converter sometimes, fex
But decoupling caps? Are they not coupling caps in the signal path to block DC?
You're right, I meant coupling capacitors.

Quote:
As I have not seen the board and the layout especially , would it be possible to desolder the IC sockets without to much risk of damaging the routing?
I have quite good tools, but anything connected to a big heatsucking copper area is always difficult to desolder (like swollen filter caps on PC motherboards, they are a pain in the donkey to desolder)
Do you realize I've put the opamps on sockets so that you don't need to desolder anything - and now you come and ask me about desoldering the sockets themselves?
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Old 8th April 2013, 03:31 AM   #846
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Mr. Nick, Sir, thank you so much for the tutorial on building FIR filters. Sorry about the late reply. I had to get out, and listen to live music this weekend. 2 weeks ago I thought fir filters were something that went on the shower drain. Now I am listening to music on my new toy. It has replaced an elderly Marchand XM9 in my pile. One question, if I use either channel 4 or 5, I cannot get the output graph to sum to a flat line in Najda Under Control. It is an either or thing. Should I ignore it as a glitch? I am using channels 1, 2, 3, 5, 6, and 7. And it is working perfectly. Sounds pretty good to my antique ears! Thanks again for all your help. Very cool toy!

No I can't f***ing hear it so turn it up real LOUD!
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Old 8th April 2013, 03:45 AM   #847
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Oh yeah, that miniature remote from China off Ebay for cheap, sucked the life out of the battery just sitting there. Maybe not a great deal.
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Old 8th April 2013, 06:04 AM   #848
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Quote:
Originally Posted by chaparK View Post
You're right, I meant coupling capacitors.


Do you realize I've put the opamps on sockets so that you don't need to desolder anything - and now you come and ask me about desoldering the sockets themselves?
I said sorry
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Old 8th April 2013, 10:33 AM   #849
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by JLOP View Post
Thanks for the nice tutorial with rePhase ! What about phase correction itself
I suggest you check the rePhase thread:
rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool


Quote:
Originally Posted by rubofdagreen View Post
Mr. Nick, Sir, thank you so much for the tutorial on building FIR filters. Sorry about the late reply. I had to get out, and listen to live music this weekend. 2 weeks ago I thought fir filters were something that went on the shower drain. Now I am listening to music on my new toy. It has replaced an elderly Marchand XM9 in my pile. One question, if I use either channel 4 or 5, I cannot get the output graph to sum to a flat line in Najda Under Control. It is an either or thing. Should I ignore it as a glitch? I am using channels 1, 2, 3, 5, 6, and 7. And it is working perfectly. Sounds pretty good to my antique ears! Thanks again for all your help. Very cool toy!

No I can't f***ing hear it so turn it up real LOUD!
That's cool Mr. Mark! If you want to send me your setup files on my email, I can check what's the issue with channels 4 or 5 you mentioned above.

Quote:
Originally Posted by rubofdagreen View Post
Oh yeah, that miniature remote from China off Ebay for cheap, sucked the life out of the battery just sitting there. Maybe not a great deal.
Maybe it just needs a fresh battery
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Old 8th April 2013, 07:46 PM   #850
Ryssen is offline Ryssen  Sweden
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Is there an error in the manual regarding the +5v line?On the pcb it says one thing,and in the manual another.
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