capacitor question (p3a) - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th January 2004, 08:20 PM   #1
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Default capacitor question (p3a)

I've a question about the input capacitor for elliot's p3a. It's supposed to be a 4.7uF capacitor. Now, in a guide somewhere i read its supposed to be a di-electric (preferably) polypropylene/polystyrene

On digikey (where i'm getting the rest of my parts) the ony thing that come up w/ dielectric are ceramic caps. Also polypropylene/polystyrene only go up to 2.2uF i believe (and their physical size is quite large, so 2 wouldn't fit on the board ..).

Anyway, any comments as to which i should use (preferably the digikey part number).

Thanks.

would this one work (part number: 495-1131-ND)?
It does say in the data sheet its a dielectric.

http://ca.digikey.com/scripts/DkSear...110246&Site=CA
  Reply With Quote
Old 26th January 2004, 08:46 PM   #2
Freddie is offline Freddie  Sweden
diyAudio Member
 
Join Date: Oct 2000
Location: Sweden
The capacitor you suggested will work just fine
  Reply With Quote
Old 26th January 2004, 08:46 PM   #3
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
4.7 uF polypropylene is quite common...a search would do the trick.

If im not mistaken Farnell got some.

Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
  Reply With Quote
Old 26th January 2004, 08:51 PM   #4
diyAudio Member
 
Cradle22's Avatar
 
Join Date: Jan 2003
Location: Dortmund, Germany
Hi!

The digikey item you've selected would work for you. It is a MKT cap, which is considered inferior to types like MKP.

But MKP (preferred) or FKP are bigger than MKT/MKS caps.

For me, preferred order would be:
Polarized elko, bipolar elko, ceramics, MKS, MKT, MKP, FKP, Mica (and maybe paper-in-oil caps)
But FKP and Mica should be out of question (not in production in the needed value range, or way too expensive and too big).

You could even omit the input cap, if you've got no DC-offset from your pre-amp / source (but always check, otherwise you could destroy your speakers).

Oh, and the size does not really matter. I am using pretty big Mundorf caps, mounted "outside" of the PCB (you can always try using caps intended for loudspeaker XO designs, since they often have lower voltage ratings, and therefore are smaller).

Or get polarized BlackGate elkos, like a lot of people do for their GainClones...

Hope this helped,

Arndt
__________________
************************
A Sacrifice For Freedom
  Reply With Quote
Old 26th January 2004, 09:44 PM   #5
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
We have been through this for decades! If you want the 'best' then only teflon will do, next is polystyrene, then polypropylene, then polycarbonate, then down the road, is mylar. Significant DA is the most important difference.
  Reply With Quote
Old 26th January 2004, 09:45 PM   #6
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Quote:
Originally posted by Cradle22
Hi!

The digikey item you've selected would work for you. It is a MKT cap, which is considered inferior to types like MKP.

But MKP (preferred) or FKP are bigger than MKT/MKS caps.

For me, preferred order would be:
Polarized elko, bipolar elko, ceramics, MKS, MKT, MKP, FKP, Mica (and maybe paper-in-oil caps)
But FKP and Mica should be out of question (not in production in the needed value range, or way too expensive and too big).

You could even omit the input cap, if you've got no DC-offset from your pre-amp / source (but always check, otherwise you could destroy your speakers).

Oh, and the size does not really matter. I am using pretty big Mundorf caps, mounted "outside" of the PCB (you can always try using caps intended for loudspeaker XO designs, since they often have lower voltage ratings, and therefore are smaller).

Or get polarized BlackGate elkos, like a lot of people do for their GainClones...

Hope this helped,

Arndt

that was the answer i was looking for, thank you

btw, in my gc i'm using a BG cap ..

Magura: That's why I specified digikey .. i know i can get it from other places, but when you have to pay $10+ for shipping from each source, you want to have as few sources as possible (it'll turn out to be 1 in my case .. just digikey, which is only $8 in shipping charges)
I don't want to order from newark just for one cap if i don't have to ..
  Reply With Quote
Old 26th January 2004, 09:47 PM   #7
mhb is offline mhb  United States
diyAudio Member
 
Join Date: Oct 2003
Location: Southwest
Elizard,

The cap you identified has 15mm lead spacing, you need a box cap with 5mm lead spacing.

The Epcos 50v 3.3uF will work and fit fine. That'll give you an F3 of 2hz, so you shouldn't lose any LF performance

Cheers,

M
  Reply With Quote
Old 26th January 2004, 09:52 PM   #8
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Quote:
Originally posted by mhb
Elizard,

The cap you identified has 15mm lead spacing, you need a box cap with 5mm lead spacing.

The Epcos 50v 3.3uF will work and fit fine. That'll give you an F3 of 2hz, so you shouldn't lose any LF performance

Cheers,

M

an even better response, thank you!
  Reply With Quote
Old 27th January 2004, 05:11 AM   #9
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Ok, another question. For the cap/resistor connected in the mains in the following image, is it a connection that's between live/neutral? As well, does the resistor have to be any significant wattage, or just a simple 1/4watt?

http://sound.westhost.com/p3a-f2.gif

Also, is there a benefic to actually using the resistor/cap across the live/neutral? What is it?

oh yeah, and how "risky" would it be to use 35V capacitors in the power supply (i've some 33000uF lying around)? The rails should be around 30-32V (my transformer is 22v secondaries)?
  Reply With Quote
Old 27th January 2004, 06:43 AM   #10
diyAudio Member
 
Join Date: Jan 2004
Location: Cape Town
Quote:
oh yeah, and how "risky" would it be to use 35V capacitors in the power supply (i've some 33000uF lying around)? The rails should be around 30-32V (my transformer is 22v secondaries)?
I honestly can't recommend 35V types for this Power Supply. They are rated to 35V DC with no ripple. With the ripple coming out of the bridge (full wave rectified AC) the cap will be operating outside it's rating and will probably suffer overheating problems, leakage and even failure.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Capacitor Question... SigloOne Tubes / Valves 26 30th May 2013 10:42 AM
PSU Capacitor question Cloth Ears Chip Amps 11 17th January 2010 11:56 AM
Capacitor question... Again and again... Dxvideo Chip Amps 14 9th January 2008 08:27 AM
capacitor question crippledchicken Solid State 3 31st October 2007 09:12 PM
Capacitor Question audiodumb Car Audio 15 22nd June 2005 03:49 PM


New To Site? Need Help?

All times are GMT. The time now is 06:10 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2