Tube Compressor - Page 3

Nigel Goodwin · 15th April 2006, 03:00 PM

Quote:

Originally posted by Ahmad_tbp
it didn t work ...
i changed the two input couplage caps to 47n and the output couplage cap to 1uf , and use it before pre ,
it didn t work !
any idea ???????

Have you made sure it's all connected properly?, try fault finding, it's a very simple circuit.

When you say it doesn't work, what doesn't work?.

Ahmad_tbp · 15th April 2006, 03:08 PM

i mean it doesn t work correctly :P ...
it s a very loud sawtooth or square wave around 80/100 hz ( i m not sure bout the wave and freq , i don have a scope ) comin out of it , but when i turn the 2nd pot (25k) all the way down the noise become silence suddenly , i connected my signal generator to it , very very little pulsin sound come out of it !!!

Geek · 15th April 2006, 03:19 PM

Sounds like you have the + and - inputs reversed.

Ahmad_tbp · 15th April 2006, 07:53 PM

+ and - inputs reverse ? no ...
i checked all the wires and pcb again and again ,, no error i think ,,, any idea ?

Geek · 15th April 2006, 08:59 PM

Ummm, what else can cause this... transistor in backwards or one that's leaky, R/C time constant too short (getting FB through the LED/LDR), which can also happen with correct R/C if the LDR is in the wrong spot in the circuit and finally, the 3900 is a hi-Z device - incorrect wire dressing wreaking havoc.

Ahmad_tbp · 15th April 2006, 09:11 PM

Quote:

transistor in backwards or one that's leaky, R/C time constant too short (getting FB through the LED/LDR),

no man ! i m talkin bout the valve comp/limiter schematic i sent , i built it , ...
here s the pcb , maybe i make a mistake and didn t seen it

Geek · 15th April 2006, 11:47 PM

Quote:

Originally posted by Ahmad_tbp

no man ! i m talkin bout the valve comp/limiter schematic i sent...

Ah, OK!

Then what you're describing is powersupply ripple. It needs a superclean supply and good decoupling.

Nigel Goodwin · 16th April 2006, 09:14 AM

Quote:

Originally posted by Ahmad_tbp

here s the pcb , maybe i make a mistake and didn t seen it

Just wondering?, why make a PCB and then not mount the valve holders on it? - it seems rather a waste of time?. If you're mounting the valve holders on a chassis, why not hand wire them? - in classical valve fashion (particularly for something as simple as this).

The old TV manufacturer KB actually manufactured valve colour TV sets all hand wired without PCB's! - incredible what you can do!.

Ahmad_tbp · 16th April 2006, 07:08 PM

cuz it s just a test pcb , i ll built preamp,comp and tone control on one pcb ...
and u said hand wired .. does it make more noise ???
and is my problem is my power supply ?

Ahmad_tbp · 16th April 2006, 07:31 PM

wat if i use this power supply ?
http://www.diyaudio.com/forums/attac...amp=1144698398

15th April 2006, 03:08 PM	#22
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Kayseri/Turkey	i mean it doesn t work correctly :P ... it s a very loud sawtooth or square wave around 80/100 hz ( i m not sure bout the wave and freq , i don have a scope ) comin out of it , but when i turn the 2nd pot (25k) all the way down the noise become silence suddenly , i connected my signal generator to it , very very little pulsin sound come out of it !!! __________________ Marge, don't discourage the boy! Weaseling out of things is important to learn. It's what separates us from the animals! Except the weasel.

15th April 2006, 07:53 PM	#24
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Kayseri/Turkey	+ and - inputs reverse ? no ... i checked all the wires and pcb again and again ,, no error i think ,,, any idea ? __________________ Marge, don't discourage the boy! Weaseling out of things is important to learn. It's what separates us from the animals! Except the weasel.

16th April 2006, 07:08 PM	#29
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Kayseri/Turkey	cuz it s just a test pcb , i ll built preamp,comp and tone control on one pcb ... and u said hand wired .. does it make more noise ??? and is my problem is my power supply ? __________________ Marge, don't discourage the boy! Weaseling out of things is important to learn. It's what separates us from the animals! Except the weasel.

16th April 2006, 07:31 PM	#30
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Kayseri/Turkey	wat if i use this power supply ? http://www.diyaudio.com/forums/attac...amp=1144698398 __________________ Marge, don't discourage the boy! Weaseling out of things is important to learn. It's what separates us from the animals! Except the weasel.

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15th April 2006, 03:19 PM	#23
Geek diyAudio Member Join Date: Sep 2004	Sounds like you have the + and - inputs reversed.

15th April 2006, 08:59 PM	#25
Geek diyAudio Member Join Date: Sep 2004	Ummm, what else can cause this... transistor in backwards or one that's leaky, R/C time constant too short (getting FB through the LED/LDR), which can also happen with correct R/C if the LDR is in the wrong spot in the circuit and finally, the 3900 is a hi-Z device - incorrect wire dressing wreaking havoc.

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