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Old 21st March 2012, 12:53 AM   #721
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Fawlty ?
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Old 21st March 2012, 12:55 AM   #722
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Depends what he means by that.
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Old 21st March 2012, 01:00 AM   #723
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Old 21st March 2012, 01:24 AM   #724
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Towers. So increased bias doesn't increase linearity. Why does it have the affect of decreasing distortion in many cases?
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Old 4th April 2012, 07:52 PM   #725
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Quote:
Originally Posted by buzzforb View Post
put small caps on output of dcb1 and see if that helps.
Greetings,

This is my first post. I have been reading/learning here for a while, but didn't have anything to contribute until now.
I built a hard wired version of the BA-2, and experienced a brief turn-off noise from the amp. I took a look at the outputs with my scope, and found that there was a very high frequency oscillation transient causing the sound. After some puzzling over the problem, on a hunch I moved the gate stopper resistors, connecting them directly to the mosfet gate leads. They had been connected to the gates via about 1.5 inches of wire. This completely solved the problem. The amp had shown no instability while powered up. I later noticed that Papa mentioned that mosfets can make very good oscillators with just a short length of hook up wire on their gates. I don't know if this happening with your amp, Yap BC, but it might be.

Thanks Papa. You are a great teacher!
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Old 15th April 2012, 04:12 AM   #726
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Hi,
Am i correct that i would need two BA3 boards for a stereo Balanced BA3? If i also want inbalanced inputs, is there way to implement it?
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Old 15th April 2012, 06:09 AM   #727
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yes, and yes

how to do it balanced have been shown
but not how to wire the single ended to balanced input

I would surely like to see it too
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Old 16th April 2012, 07:36 AM   #728
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Default Turn-off noise

Quote:
Originally Posted by mikegranger View Post
Greetings,

This is my first post. I have been reading/learning here for a while, but didn't have anything to contribute until now.
I built a hard wired version of the BA-2, and experienced a brief turn-off noise from the amp. I took a look at the outputs with my scope, and found that there was a very high frequency oscillation transient causing the sound. After some puzzling over the problem, on a hunch I moved the gate stopper resistors, connecting them directly to the mosfet gate leads. They had been connected to the gates via about 1.5 inches of wire. This completely solved the problem. The amp had shown no instability while powered up. I later noticed that Papa mentioned that mosfets can make very good oscillators with just a short length of hook up wire on their gates. I don't know if this happening with your amp, Yap BC, but it might be.

Thanks Papa. You are a great teacher!
I am using a BA-2 board purchased from DiyAudio Store. I supposed that the components' placement and tracks' length on the board would have been optimized to prevent oscillation.
Since I do not have a scope, I just used some trial and error methods to rectify it. I guessed that the main power supply switch in my amp could have contributed to the problem during turn-off, so I just added some X2 capacitors with a total value of 0.1 microfarad to the power on-off switch to improve on the suppression during turn-off. No more turn-off noise. Even occasionally when it happens, the turn-off noise is very much reduced. Anyway, thanks for your suggestion.
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Old 16th April 2012, 09:13 PM   #729
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wrong guess , except if you deliberately want mute function

for unbalanced input , just ground neg input

RCA hot to +in , RCA gnd to gnd
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Old 16th April 2012, 09:39 PM   #730
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corrected

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wrong guess ......
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