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B1 Buffer Preamp
B1 Buffer Preamp
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Old 28th June 2013, 12:26 PM   #3771
sangeet2 is offline sangeet2  Germany
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My test setup is this:
Macbook-Apogee One-Rotel HiFi amp.
I also tried it with a CD player as source...
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Old 28th June 2013, 12:27 PM   #3772
sangeet2 is offline sangeet2  Germany
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Originally Posted by KatieandDad View Post
What is the output impedance of your source ?
Apogee One is 30 Ohm
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Old 28th June 2013, 12:30 PM   #3773
KatieandDad is offline KatieandDad  United Kingdom
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If everything is OK then it might be down to the rest of the set-up. The B1 is pretty transparent so wont affect the frequency response of the rest of the set-up. Try taking the B1 out of the system by simply connecting the wiper of the volume pot to the power amplifier.
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Old 28th June 2013, 12:32 PM   #3774
sangeet2 is offline sangeet2  Germany
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Hmm, if I dont put the B1 inbetween everything is good. In the Rotel I am using the Input for tuner...
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Old 28th June 2013, 12:35 PM   #3775
KatieandDad is offline KatieandDad  United Kingdom
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In my B1 I used DIY boards derived from the PCB layouts on the Pass DIY site. Even then I found discrepancies. I would check your boards very carefully by reverse engineering the schematics. Also check VERY carefully for hairline whiskers of copper or solder.
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Old 28th June 2013, 12:35 PM   #3776
sangeet2 is offline sangeet2  Germany
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Quote:
Originally Posted by KatieandDad View Post
Try taking the B1 out of the system by simply connecting the wiper of the volume pot to the power amplifier.
Ok will do this
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Old 28th June 2013, 12:36 PM   #3777
sangeet2 is offline sangeet2  Germany
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Quote:
Originally Posted by KatieandDad View Post
In my B1 I used DIY boards derived from the PCB layouts on the Pass DIY site. Even then I found discrepancies. I would check your boards very carefully by reverse engineering the schematics.
Did this already but will do it again,
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Old 28th June 2013, 12:44 PM   #3778
sangeet2 is offline sangeet2  Germany
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Quote:
Originally Posted by KatieandDad View Post
If everything is OK then it might be down to the rest of the set-up. The B1 is pretty transparent so wont affect the frequency response of the rest of the set-up. Try taking the B1 out of the system by simply connecting the wiper of the volume pot to the power amplifier.
Without the B1 pot is working fine
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Old 28th June 2013, 01:06 PM   #3779
KatieandDad is offline KatieandDad  United Kingdom
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Reverse engineer the board. I suspect that there is an error somewhere.
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Old 28th June 2013, 01:16 PM   #3780
sangeet2 is offline sangeet2  Germany
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Ok, it looks like I found a msitake on this PCB from the other forum. There is one cap with 0,1uF called C4. This one is not in the original B1
If I take this off my pot behaves normal

Thanks alot for your input!
Click the image to open in full size.
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