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Old 12th March 2012, 10:53 AM   #11
AndrewT is offline AndrewT  Scotland
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......... in the later version, post #383, I moved to a lower value because I found that the bass was more prominent this way.
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makes no difference whatever to the sound quality.....
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why bother fitting C12 or even the RC filter if it does not clean up the power rail.
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NOT 'clean up the power rail' if this appears to reduce bass
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If you increase R5 to match the 100R on the other rail, you reduce the half wave rectified 'ripple' and thereby improve the quality of the DC, clean it up, if you will.

Correspondingly, if you leave R5 at 10R and boost the associated capacitor by a factor of ten to preserve the time constant, again, you clean up the rail, no question.

BUT, in both cases, for reasons uncertain, you lessen the bass delivery.
I read confusion in these answers/replies.
First, reducing the R improves the bass.
Next, increasing the C does not change the sound
Then the following all say reduces the bass, if the time constant is maintained at it's original value.

I found that increasing the C to bring the time constant back up to match the other side and to match the original seemed to me to give a slight improvement in the bass response/sound.
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Old 12th March 2012, 12:04 PM   #12
AKSA is offline AKSA  Australia
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Sorry Andrew,

Your findings, not mine. If you leave the cap at 100uF, but reduce R5 to 10R, bass is better, but time constant is far shorter than if R5 had been left at 100R.

Kapitz?


Hugh
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Last edited by AKSA; 12th March 2012 at 12:14 PM.
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Old 15th April 2012, 03:13 PM   #13
unmibh is offline unmibh  Bosnia and Herzegovina
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Hi Woody/All

I think I found a mistake on the PS schematic on post 1, C17 and C18 polarity. I think the correct one on post 383.

Regards,
Rom
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Old 15th April 2012, 10:42 PM   #14
AKSA is offline AKSA  Australia
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Thanks Rom,

I agree; you are quite right. Accordingly I have amended the gif, and deleted the pdf which takes more time to amend.

I hope this is the very last mistake of this project! My apologies for inconvenience, though I note the polarities on the pcb are correct. All in all, the FetZilla is now well documented.

Cheers,

Hugh
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Old 31st May 2012, 12:01 PM   #15
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Regarding the rectifier diodes,does they need a heatsink?
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Old 31st May 2012, 11:54 PM   #16
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Regarding the rectifier diodes,does they need a heatsink?
hey meanman , when i was building my first fetzilla , i was running it open on a bench and could barely detect any warmth , let alone enough heat to require heat sinks . ymmv

build it and see for yourself . they can always be added if you find it necessary .

good to see some more folks building these . a lot more boards were sold than people building them .

you won't be disappointed

cheers Woody
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Old 1st June 2012, 06:14 AM   #17
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This is the current state of one channel.Maybe this weekend I'll start up the amp but first I've to build a light bulb tester.Do I need to set the trimpots first before aply the voltage
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File Type: jpg DSCN4935.JPG (935.5 KB, 757 views)

Last edited by meanman1964; 1st June 2012 at 06:21 AM.
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Old 1st June 2012, 08:13 AM   #18
AKSA is offline AKSA  Australia
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No, should be just fine without special care; it's set up to prevent the output stage going overcurrent regardless of setting.

Keep going, MM, nearly there.....

Hugh
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Old 1st June 2012, 08:51 AM   #19
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So no need to set for example the bias pot max resistant,offset pot half way etc.?Can I clean the pcb with alcohol?
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Old 1st June 2012, 01:20 PM   #20
AKSA is offline AKSA  Australia
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Yes, no problem, set to halfway by all means. Clean with alcohol then polish with a stiff brush, and then lacquer with protectant... to protect from moisture.
Cheers

Hugh
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