Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Are 1978 low leakage (LR) capicitors noteworthy today?
Are 1978 low leakage (LR) capicitors noteworthy today?
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 11th June 2016, 01:28 AM   #1
62vauxhall is offline 62vauxhall  Canada
diyAudio Member
 
Join Date: Mar 2011
Location: Greater Vancouver Regional District, BC
Default Are 1978 low leakage (LR) capicitors noteworthy today?

Am about to start replacing electrolytic capacitors in a lowish end preamp and have obtained new Rubycons (mostly) from a nearby parts shop. As I examined the original capacitors to record their values, two in the phono section were distinctive with an orange wrapper and prompted a little research. Likely made by Elna and marked LR that from what I read indicates Low Leakage. I was advised by the parts store staff that it is an irrelevant distinction with modern capacitors as they would all be considered Low Leakage by 1978 standards.

There were some thread posts that concur with this while others say there would be some benefit in locating current even lower leakage replacements. In my case that would mean buying from an online US vendor and shipping to Canada. Since that would translate into $20 - $25 for two small capacitors, I cannot justify the expense.

Am I safe in my thinking that using a modern general purpose capacitor in this application would not be a downgrade from the originals as in introducing more noise? Or, just leave the originals in place?

Also, since the phono stage involves low level signal, is the capscitor's voltage rating going to be critical in this instance as long as not less than original is used? I could be wrong but from my minimal understanding, signal rarely passes through an electrolytic.

Last edited by 62vauxhall; 11th June 2016 at 01:31 AM.
  Reply With Quote
Old 11th June 2016, 01:50 AM   #2
rayma is online now rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by 62vauxhall View Post
Am I safe in my thinking that using a modern general purpose capacitor in this application
would not be a downgrade from the originals as in introducing more noise? I could be wrong
but from my minimal understanding, signal rarely passes through an electrolytic.
Leakage is specified for most new electrolytics, so compare it to the original's leakage spec.
A higher voltage/temperature part will have less leakage, in general.
At any rate, you can be sure that the original electrolytic capacitors are way out of spec by now.

Signal current does go though the electrolytic capacitors in most circuits, but the capacitance
value is chosen large enough to minimize any signal voltage drop across the capacitor.

Last edited by rayma; 11th June 2016 at 01:54 AM.
  Reply With Quote
Old 11th June 2016, 04:57 AM   #3
62vauxhall is offline 62vauxhall  Canada
diyAudio Member
 
Join Date: Mar 2011
Location: Greater Vancouver Regional District, BC
The capacitors I got to replace those orange wrapped Elnas are Rubycon 63 volt 1uF whereas the Elnas are 50 volt.

Oddly, I cannot locate a data sheet on these Rubycons which have printed on their wrapper (blue) CE W which seems to be a valid series designation. Using Rubycon CE W series as a search term led to a reference for Rubycon TWSS but no data sheet for that either. Could be that what I have are NOS.

In any case, I guess they're going as replacements for the orange Elnas since, as you say, those are probably past their prime.

It almost seems humorous to be concerned about these because the cost was $1 for 5 capacitors - twenty cents each.
  Reply With Quote
Old 11th June 2016, 07:55 AM   #4
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
When training technicians professionally, I often point out that parts are cheaper than labor. I do not recommend just shotgunning circuits, but when someone wastes $10 of labor trying to determine if a 20 cent part is bad, that is not efficient. if it is suspect, replace it.
  Reply With Quote
Old 11th June 2016, 08:20 AM   #5
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Are 1978 low leakage (LR) capicitors noteworthy today?
I can't remember the designation now but I seem to recall some orange wrapper caps were bi-polar (non polarised). Just make sure that all the originals do have a polarity marking on them.

I would have no hesitation using modern parts to replace so called 'low leakage' devices of yesteryear.
  Reply With Quote
Old 11th June 2016, 08:26 AM   #6
woody is offline woody
diyAudio Member
 
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
If these were in the signal path you might want to replace them with film caps if you have the room for them.
  Reply With Quote
Old 11th June 2016, 09:09 AM   #7
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
In any case I would avoid using 1978 electrolytic capacitors, even more if they sat unused for 38 years.
__________________
Design/make/service musical stuff in Buenos Aires, Argentina, since 1969.
  Reply With Quote
Old 11th June 2016, 03:13 PM   #8
62vauxhall is offline 62vauxhall  Canada
diyAudio Member
 
Join Date: Mar 2011
Location: Greater Vancouver Regional District, BC
Thanks everyone for your replies.

Those capacitors are polarized and looking at the schematic, the positive leads are connected to pins 1 and 7 of an SJ4558 op amp IC with the negative going to the function switch. Circuit diagram says 2.3 volts at that point so my conclusion is that they are in the signal path.

There looks to be a fair bit of "shoulder room" on the board to accommodate a larger capacitor and the only consideration would be lead spacing but that could be negated with insulation tubing on the leads.

As I previously mentioned, ordering small quantities of inexpensive parts from a US vendor is cost prohibitive. But I see no reason why I should not be able to obtain film capacitors (probably polypropylene) with the required values from the local parts store I frequent. My work has me travelling throughout the city so finding myself in their neighborhood is likely during the upcoming week. If, for some reason appropriate film capacitors are not on hand, I will use the electrolytics I already have.

There is one concern I have about using a film capacitor in a phono preamp section and that is physical size vs induced hum.

It stems from my re-building a Heathkit AA-32 tube amp a few years ago which I assembled from a kit in 1968. I replaced every single thing inside that amp except for transformer and the switches/controls. I used Sprague Orange Drops to replace all the original film caps and everything was fine except for a hum present only on the MAG PHONO input. I spent a considerable amount of time troubleshooting and solicited help from a technician familiar with tube equipment who had it on his bench for several weeks. I have even posted on this site about it but the source of the hum remained elusive.

I found it odd that this hum started only after installing all new components. While reading online about this topic, I came across something suggesting that increasing the surface area of a capacitor may make it more susceptible to picking up noise especially in areas involving low level signals - like a phono preamp.
  Reply With Quote
Old 11th June 2016, 03:24 PM   #9
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Are 1978 low leakage (LR) capicitors noteworthy today?
imo there is nothing worse than seeing incorrect and oversized parts 'made' to fit in something. Your observations are correct on the hum too.

(one thing you might consider looking at is possible replacement of the 4558 opamps. You may well find that swapping those to a different device gives a noticeable improvement in quality)
  Reply With Quote
Old 11th June 2016, 03:39 PM   #10
62vauxhall is offline 62vauxhall  Canada
diyAudio Member
 
Join Date: Mar 2011
Location: Greater Vancouver Regional District, BC
Alright then, I'll go with the parts I already have. And yes, I intend on replacing that op amp.

I read endorsements for NE5532 and OPA2134 so I purchased one of each. I also got a socket because I wanted to see if I can tell any difference between them - and the original too for that matter.

If the difference is subtle, I may not even notice. I spent too many years riding a motorcycle and playing in a band so at this point in my life, hearing is not what it was.
  Reply With Quote

Reply


Are 1978 low leakage (LR) capicitors noteworthy today?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Headscratching with voltage & low leakage Oceanw Power Supplies 21 18th March 2015 07:10 PM
How can I apply a 24db/oct LR high and low pass filter to a WAV file? MikeHunt79 PC Based 12 21st May 2010 07:55 AM
LR 4th order vs LR 8th order crossover redliner Subwoofers 1 8th January 2009 12:32 AM
Low Leakage Capacitors Question klauseva Parts 4 20th August 2008 06:41 AM
Noteworthy upgrade for CD playback- how? stefanK Digital Source 0 18th May 2006 10:50 AM


New To Site? Need Help?

All times are GMT. The time now is 03:12 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki