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Old 13th June 2013, 03:14 PM   #3731
Rixsta is offline Rixsta  United Kingdom
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Heres my B1, the power comes from transformer on the AC wires then to a rectifier then to the B1. any reason i should be getting hum ? on the output ? about to troubleshoot.


IMAG0021.jpg

IMAG0022.jpg

Can i Ground the center-tap wire ?
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Old 13th June 2013, 03:41 PM   #3732
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Disconnected input wires - no change

Volume up full and B1 output is quieter than output from audio source (this part surely not a grounding issue ?)

taking ground lead from F5 to B1 outputs makes more hum

Tried laptop PSU same problem!
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Old 13th June 2013, 03:57 PM   #3733
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Quote:
Originally Posted by Rixsta View Post
I have a lovely 50Hz hum on This B1 sounds the same as the transformer

CHECK your grounding !!!!
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Old 13th June 2013, 05:25 PM   #3734
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Disconnected the whole B1 lol and problem there, as soon as i plug in the music source hum, if i unplug the source. in this case a mp3 player. hum goes.
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Old 13th June 2013, 07:34 PM   #3735
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Quote:
Originally Posted by AudioLapDance View Post
I did a quick search but didn't find anything specific ...

Loving my B1!

Thinking of another circuit, can the B1 work with lower ps voltage: 12-14V?

From the 2SK170 datasheet:

Note: IDSS classification GR: 2.6~6.5 mA, BL: 6.0~12 mA, V: 10~20 mA




Would it be as simple as using the GR grade (2.6~6.5 mA) instead of the BL grade (6.0~12 mA)?

Or are different FETs required?

Cheers,
Jeff
Keep the same BL grade.
The dissipation will be a bit less due to less voltage.
That would allow a higher Idss if you have any.
But the Idss should be measured at the voltage the devices will see in the circuit.
If the B1 runs on 13Vdc then the Idss should be measured at 6.5Vds
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Old 13th June 2013, 07:43 PM   #3736
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A B1 does not need a dual polarity PSU.
You mention centre tap and I see two smoothing caps.
What supply have you ended up with?
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Old 13th June 2013, 10:13 PM   #3737
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Hi, thanks Problem seems to be a ground loop with the F5, the B1 is disconnected completely and there is hum still the same loud and same hum.

I have centre tapped transformer
2x 24v for the F5
2x 12v for the B1 (only one of the 12v)
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Old 13th June 2013, 10:44 PM   #3738
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A B1 does not need a dual polarity PSU.
You mention centre tap and I see two smoothing caps.
What supply have you ended up with?
From experience I an tell that the DCB1 (with symmetrical supply and no input/output caps) beats an asymmetrical fed B1. Win-win situation: cheaper and better. No need for using brick sized caps then.
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Old 14th June 2013, 11:41 AM   #3739
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Run it off of a 24 volt SLA battery stepped down. Even a staight 12 V sounds great no HUM!! only need charing once every week.
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Old 20th June 2013, 12:36 AM   #3740
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Are you sure 12v can sound ok ? im running the B1 on 13v at the moment as I only have 13 or 26 avalible, the 13v sounds distorted at high levels to me.

Does anyone know if i can run the B1 at the 26volts i have ? would I need to change anything thanks ?
got rid of all my hum problems btw learnt a lot!
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