Parallel Capacitor Question - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 20th June 2012, 01:03 AM   #1
diyAudio Member
 
Join Date: Mar 2012
Location: Redmond, WA
Default Parallel Capacitor Question

I am restoring an old Pyramid PS/1 speaker which has a switchable built-in crossover for use with the RTR subwoofer module. I just picked these up at a garage sale and am digging in to replace rotted surround and questionable old capacitors. I wonder if anyone knows why Pyramid elected to bundle 4 75mfd 75VNP's in parallel & right next to them install a single 300mfd 50VNP. Both speaker crossovers look identical, neatly glued together as manufactured. They're all NP axials, and the difference is that the bundled 75mfd's are in the series circuit to the drivers, whereas the 300mfd singletons are paired with a choke in a tuning shunt. I decided to launch a search (unsuccessful thus far) before replacing the bundled 75mfd's with singleton 300s.

There are hopefully some thoughts out there on this . . . . .
  Reply With Quote
Old 20th June 2012, 02:01 AM   #2
diyAudio Member
 
Inductor's Avatar
 
Join Date: Feb 2006
Location: Cascais
Just to mention the fact that the 4(?) caps can accept a higher voltage (4x75V?) than a single one of 50/75V.
__________________
NEXT-proaudio Portugal
  Reply With Quote
Old 20th June 2012, 08:44 AM   #3
diyAudio Member
 
Join Date: Nov 2009
Location: Los Angeles
Quote:
Originally Posted by Inductor View Post
Just to mention the fact that the 4(?) caps can accept a higher voltage (4x75V?) than a single one of 50/75V.
Not in parallel they can't. Has the XO been modified or is it 'stock'?

G
  Reply With Quote
Old 20th June 2012, 12:03 PM   #4
DavidL is offline DavidL  United States
Banned
 
Join Date: Jul 2010
The reasons for the bundled caps might be simply that they got a good deal cost wise on caps and just used what they had on hand. As long as the single cap equals the capacitance of the bundled caps and equals or exceeds the voltage rating then it makes no difference.Perhaps the ESR would be lower for the bundled caps in total but shouldn't be an issue anyway unless they are really bad to begin with.
  Reply With Quote
Old 20th June 2012, 12:14 PM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
4 off paralleled 75uF caps will have many differences from a 300uF cap.
These differences could be ESR, Ripple capacity, volume, cost, etc...................
ESR and ripple capacity are possibly the most important. Packaging space and cost will come into the productionising decisions at some point.

BTW,
do you think that 75uF equals 75mfd?
I am not sure.
__________________
regards Andrew T.
  Reply With Quote
Old 20th June 2012, 01:14 PM   #6
diyAudio Member
 
Join Date: Sep 2006
Location: New England
Peter Snell, innovative founder of Snell Acoustics commonly used bundles of NPE's bypassed by a single pF disk cap (at bottom to glue the bundle to the xo board) to attain a value he needed. Below is a pic of just one example found in his famous Snell Model A.Click the image to open in full size.
  Reply With Quote
Old 20th June 2012, 01:24 PM   #7
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
Quote:
BTW,
do you think that 75uF equals 75mfd?
I am not sure.

we've had that discussion

mfd = micro and not milli farads?
  Reply With Quote
Old 20th June 2012, 02:33 PM   #8
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
mfd = milli femto deci
But, from the context, I'm guessing the manufacturer meant uF.
__________________
regards Andrew T.
  Reply With Quote
Old 20th June 2012, 06:19 PM   #9
diyAudio Member
 
Join Date: Mar 2012
Location: Redmond, WA
Thanks for your input, gentlemen. I am certain the identical glued-up crossover blocks are as factory built - the fellow I bought the speakers from acquired them new.

OK, OK, it's microfarads.

The bundled caps look like the typical Callins I've seen in many 60s & 70s speakers, and the 300uF singletons are the really cheap no-name Al-clad cans. I'm just trying to figure out, after all the crossovers I've seen, whether designers knowingly would have chosen higher-quality caps for the in-line signal and thought so much less of the shunted signal that it warranted a decidedly lesser cap quality. I guess I've never encountered a crossover with 2 paths having such high capacitance. These fellas from Canoga Park weren't going toe-to-toe with Dave Wilson, but this speaker combo was their showpiece at the time.
  Reply With Quote
Old 20th June 2012, 07:28 PM   #10
diyAudio Member
 
LafeEric's Avatar
 
Join Date: May 2010
I'm with DavidL.
  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 in parallel with negative feedback resistor Tyimo Tubes / Valves 4 16th April 2011 09:33 PM
Series or parallel capacitor for bass X-over zebra100 Multi-Way 2 15th May 2009 09:43 AM
parallel lm3886 question ryan750 Chip Amps 2 23rd October 2008 10:37 AM
CORRECT Capacitor connection parallel to a Zener arupg Solid State 2 20th October 2007 05:39 PM
Purpose of Parallel Capacitor with AD811 I/V circuit? fastcat95 Digital Source 3 9th February 2005 06:09 PM


New To Site? Need Help?

All times are GMT. The time now is 09:41 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