Power supply capacitors

gehlhoff · 20th November 2000, 02:28 PM

I'm in the early stages of an amp layout, I'm trying to see If I can fit everything for a 4 channel 70-100 watt/channel class A/b amp in a package that will fit in my entertainment center. I wanted to go with class A, but even at 4*40 or 2*20+2*40 I won't have room for all the heatsink. (looking to bi-amp)
So right now I'm Looking for sources of capacitors suitible for power supplies. I'm looking at a supply voltage of around 90 volts. I want between 20,000 and 30,000 uf but would be willing and probably able to fit multiple caps of 5,000 or larger. Thanks for any help,

Wade

mullins · 20th November 2000, 11:59 PM

For a frame of reference I recently bought some Mallory computer grade electrolytics from Mouser, they are 75 VDC 37000 MFD and are about 145 mm tall and 75 mm in diameter. Pretty big! So I don't know, but these definitely take up a lot of space and the size and shape makes it pretty hard to fit them in a small chassis.

gehlhoff · 21st November 2000, 01:39 PM

75 volts should be plenty and give me room to expand in the future. I found some 75v 3100 uF Mallroy caps at C&H (surplus sales) for $2.50(they have others too) seems I have just enough room for 6/rail. Or 5 of another kind, or 2 of a third all giving capacitance values between 18,000 and 19,000. Any advice on what is better a lot of smaller caps or a few large caps.

Wade

vdi_nenna · 21st November 2000, 11:47 PM

http://www.meci.com

http://www.mpja.com

vdi_nenna · 21st November 2000, 11:51 PM

Sorry, mpja doesn't have caps, but they do have other electronics.

Try: http://www.apexjr.com

promitheus · 10th January 2001, 11:23 PM

I use the philips high current ones. They proved to be very good. I don´t know about their price compared to other ones.

tankcircuitnoise · 12th February 2012, 04:14 AM

Have you considered cascoding the output devices?
This makes them somewhat immune to power_supply ripple
at all frequencies, and may let you reduce the amount of
capacitance on the high-current rails.

AndrewT · 12th February 2012, 11:02 AM

Why 90Vdc supply?
70W to 100W into 8ohms can be got from +-45Vdc to +-50Vdc. 32-0-32Vac to 35-0-35Vac transformers are suitable.
These PSUs need 63V capacitors. They will be smaller and cheaper than any 75V, 80V or 100V capacitors.

21st November 2000, 01:39 PM	#3
gehlhoff diyAudio Member Join Date: Nov 2000 Location: Minnesota	lots of smal caps a couple big ones 75 volts should be plenty and give me room to expand in the future. I found some 75v 3100 uF Mallroy caps at C&H (surplus sales) for $2.50(they have others too) seems I have just enough room for 6/rail. Or 5 of another kind, or 2 of a third all giving capacitance values between 18,000 and 19,000. Any advice on what is better a lot of smaller caps or a few large caps. Wade

21st November 2000, 11:47 PM	#4
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	large or small caps http://www.meci.com http://www.mpja.com

21st November 2000, 11:51 PM	#5
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	Not mpja Sorry, mpja doesn't have caps, but they do have other electronics. Try: http://www.apexjr.com

10th January 2001, 11:23 PM	#6
promitheus diyAudio Member Join Date: Jan 2001 Location: Germany	try philips I use the philips high current ones. They proved to be very good. I don´t know about their price compared to other ones.

12th February 2012, 11:02 AM	#8
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Why 90Vdc supply? 70W to 100W into 8ohms can be got from +-45Vdc to +-50Vdc. 32-0-32Vac to 35-0-35Vac transformers are suitable. These PSUs need 63V capacitors. They will be smaller and cheaper than any 75V, 80V or 100V capacitors. __________________ regards Andrew T.


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20th November 2000, 02:28 PM	#1
gehlhoff diyAudio Member Join Date: Nov 2000 Location: Minnesota	I'm in the early stages of an amp layout, I'm trying to see If I can fit everything for a 4 channel 70-100 watt/channel class A/b amp in a package that will fit in my entertainment center. I wanted to go with class A, but even at 440 or 220+2*40 I won't have room for all the heatsink. (looking to bi-amp) So right now I'm Looking for sources of capacitors suitible for power supplies. I'm looking at a supply voltage of around 90 volts. I want between 20,000 and 30,000 uf but would be willing and probably able to fit multiple caps of 5,000 or larger. Thanks for any help, Wade

20th November 2000, 11:59 PM	#2
mullins diyAudio Member Join Date: Nov 2000 Location: Kansas	For a frame of reference I recently bought some Mallory computer grade electrolytics from Mouser, they are 75 VDC 37000 MFD and are about 145 mm tall and 75 mm in diameter. Pretty big! So I don't know, but these definitely take up a lot of space and the size and shape makes it pretty hard to fit them in a small chassis.

12th February 2012, 04:14 AM	#7
tankcircuitnoise diyAudio Member Join Date: Jan 2012	Have you considered cascoding the output devices? This makes them somewhat immune to power_supply ripple at all frequencies, and may let you reduce the amount of capacitance on the high-current rails.

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