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

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Capacitor value
Capacitor value
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
Thread Tools Search this Thread
Old 9th March 2013, 08:57 PM   #1
tony Ma is offline tony Ma  United States
diyAudio Member
Join Date: Feb 2011
Default Capacitor value

Dear All,

Sorry for a newbee questions

I like to know what you guys think with this "upgrade" scenario

Let's just say originally the Tube Pre-AMP has a 1UF capacitor

Can we substitute with some thing close to the original value such as .82UF ?

Is there any sound different?

I knew that the voltage must be the same

Let me know your insight guys

  Reply With Quote
Old 9th March 2013, 09:57 PM   #2
funk1980 is offline funk1980  Netherlands
diyAudio Member
funk1980's Avatar
Join Date: Sep 2011
Location: Groningen
Do you know the function of the cap? Smooting, coupling, powersupply, etc.

The value of a cap always depends on the surrounding circuitry. Let's assume it's a coupling cap. Combined with the impedance of the next stage, you get a high pass filter with a certain frequency. For example, if the next stage has a impedance of 10k ohm, the -3dB frequency will be 16 hertz. With a .82uF cap, the -3dB point will be 19 hertz. Just 3 hertz. But with a 1k ohm impedance, it's 159 vs 194 hertz. A 35 hertz difference. You might detect a small change in frequency response in the sound of the preamp, but not anything world chaning in my opinion.

If it's a cap e.g. tuned to prevent high frequency oscilations somewhere in the preamp, or part of the EQ network, the change might be more significant though.

Last edited by funk1980; 9th March 2013 at 10:00 PM.
  Reply With Quote
Old 10th March 2013, 11:35 AM   #3
DF96 is online now DF96  England
diyAudio Member
Join Date: May 2007
The voltage does not have to be the same. It has to be sufficient, under all normal and most fault conditions.

The value depends on exactly how the cap is used in the circuit, whether it sets a rolloff, whether it is within a negative feedback loop etc. A 20% change is unlikely to make much difference.
  Reply With Quote


Capacitor valueHide 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
mkt capacitor vs mylar capacitor Vrystaat Solid State 4 5th July 2016 04:15 PM
capacitor bully123 Pass Labs 6 8th September 2011 11:03 PM
Help needed - reservoir capacitor after reservoir capacitor wwenze Power Supplies 8 29th October 2010 01:16 PM
Looking for a capacitor OHjim Parts 2 15th January 2010 12:43 PM
Do you know what this capacitor is doing there? destroyer X Solid State 23 24th May 2009 03:08 PM

New To Site? Need Help?

All times are GMT. The time now is 01:51 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio