Leach Capacitor Upgrade

Toltec · 27th September 2011, 10:48 AM

Greetings All,

I'm a newby currently building a Leach 4.5. I've made and drilled the PCBs and have a box of components begging me to get to work. All components are pretty much standard, as per Prof Leach's BOM. It struck me that it may be worth upgrading some of the capacitors with polyprop ones before getting my soldering iron out.

Given my lack of experience, I'd really appreciate your opinions as to which ones are worth changing... I found the link below from another post for reference.

http://img166.imageshack.us/img166/8651/ampleachfq5.gif

Your thoughts are much appreciated!

Gary

Toltec · 27th September 2011, 01:30 PM

OK, just read the following article:

Capacitor Characteristics

It seems if it aint broke then don't fix it. :-)

Ron AKA · 27th September 2011, 03:48 PM

He is using some 100 uF electrolytics on the power rails, with a 100 nF bypass. You could increase the size of the electrolytics and use ones with a very low ESR. The bypasses could be increased to a 0.47 uF metalized polypropylene. Don't see any input or output caps that you need to be concerned about.

AndrewT · 27th September 2011, 04:30 PM

Caps that pass audio onto the next stage will likely benefit from better types, eg PP (either foil or metalised) instead of MKS or MKT.
The exception is the NFB DC blocker, it generally needs to be so large that only electrolytics can do the job there. But be very wary of using an electrolytic that is too low in value.
The rail decoupling should (some would say "must") be very close to the devices that can suddenly change in current, eg. output devices.

Ron AKA · 27th September 2011, 11:17 PM

This National Semiconductor article may give you some ideas on what can be done at the power supply stage.

Toltec · 28th September 2011, 07:28 AM

Thanks for the info guys!

27th September 2011, 10:48 AM	#1
Toltec diyAudio Member Join Date: Aug 2011 Location: Birmingham	Leach Capacitor Upgrade Greetings All, I'm a newby currently building a Leach 4.5. I've made and drilled the PCBs and have a box of components begging me to get to work. All components are pretty much standard, as per Prof Leach's BOM. It struck me that it may be worth upgrading some of the capacitors with polyprop ones before getting my soldering iron out. Given my lack of experience, I'd really appreciate your opinions as to which ones are worth changing... I found the link below from another post for reference. http://img166.imageshack.us/img166/8651/ampleachfq5.gif Your thoughts are much appreciated! Gary

27th September 2011, 04:30 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Caps that pass audio onto the next stage will likely benefit from better types, eg PP (either foil or metalised) instead of MKS or MKT. The exception is the NFB DC blocker, it generally needs to be so large that only electrolytics can do the job there. But be very wary of using an electrolytic that is too low in value. The rail decoupling should (some would say "must") be very close to the devices that can suddenly change in current, eg. output devices. __________________ regards Andrew T.

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27th September 2011, 01:30 PM	#2
Toltec diyAudio Member Join Date: Aug 2011 Location: Birmingham	OK, just read the following article: Capacitor Characteristics It seems if it aint broke then don't fix it. :-)

27th September 2011, 03:48 PM	#3
Ron AKA diyAudio Member Join Date: Aug 2011	He is using some 100 uF electrolytics on the power rails, with a 100 nF bypass. You could increase the size of the electrolytics and use ones with a very low ESR. The bypasses could be increased to a 0.47 uF metalized polypropylene. Don't see any input or output caps that you need to be concerned about.

27th September 2011, 11:17 PM	#5
Ron AKA diyAudio Member Join Date: Aug 2011	This National Semiconductor article may give you some ideas on what can be done at the power supply stage.

28th September 2011, 07:28 AM	#6
Toltec diyAudio Member Join Date: Aug 2011 Location: Birmingham	Thanks for the info guys!

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