Pearl: Coupling capacitor - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 18th December 2006, 01:23 PM   #1
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
Default Pearl: Coupling capacitor

Hi folks!

First a big thanks to Mr. Colburn and Mr. Pass for sharing the pearl with us!!

I'm getting my parts hopefully this week, so I can start building it - woa my excitement is really unbearable!!

One question crossed my mind: I could get my hands on an supposedly excellent cap (Mundorf Supreme: tan d: 0.0002 bei 1kHz, tan d: 0.0001 bei 10kHz, fully free of induction), however instead of the 10uF only a 1uF would fit nicely.

Are there any disadvantages if I replace the 10uF with a 1uF and raise the resistor R15 from 100K to 1MOhm (since this is a highpass and the product capacity*resitance stays the same the resonance stays also the same)?

Was this particular combination 10uF/100KOhm chosen to minimize noise? If yes would the non-magnetic Visay CMF55 low-noise resistor help?

Thanks a lot!!

With kind regards, Hannes

PS: what do you think: is a Mundorf Supreme worth the money? I mean compared to a standard Mundorf MCap that is.
  Reply With Quote
Old 18th December 2006, 05:19 PM   #2
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
It's not R15 that you're worried about--it's the input impedance of the device (presumed to be a preamp) that follows the phono stage.
Let's say that you've got a 10k input impedance in your preamp. If you're using a 1uF coupling cap, you're going to be 3dB down at roughly 17 or 18Hz (don't forget that R15 is in parallel with the preamp, lowering the Zin still further). You'll be one or two dB down well up into the audible range, no matter how you look at it.
And that's assuming that your preamp is at 10k--it might be lower, especially some of the DIY designs. If you happen to use a tube unit with a Zin of something like 100k, then things will be much better, but you'll always be at the mercy of whatever the Zin happens to be on any given preamp. In practical terms, your Pearl won't sound the same at your friend's house as it does at home and you're likely to be missing some of the bass.

Grey
  Reply With Quote
Old 19th December 2006, 07:54 AM   #3
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
Thanks a lot for your truly enlightening reply!!

Didn't thought of that.

So thats for me another proof, that one should not change circuits unless one could design them themself.

Whoa. 3dB@18Hz would really hurt

With kind regards, Hannes
  Reply With Quote
Old 19th December 2006, 12:36 PM   #4
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
There are some parts you can fiddle with and some you can't--at least without having a plan. Changing the DC blocking cap won't break the Pearl. It just won't sound the same.

Grey
  Reply With Quote
Old 21st December 2006, 11:24 PM   #5
diyAudio Member
 
Join Date: Jun 2005
Location: Dallas, Texas
Why not put a 10 uF cap in there and bypass it using your 1 uF Mundorf?
If it will fit - it may not be the most beautiful thing in the world, but
you'll get your Mundorf....
  Reply With Quote
Old 10th January 2007, 05:51 PM   #6
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
Sorry for my late reply!

Thanks a lot for your suggestion! You're right! Nice idea!

Well maybe it's not worth all the fuzz...

Cheers, Hannes
  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
Coupling capacitor selection DcibeL Chip Amps 23 18th July 2011 04:20 AM
Pearl Capacitor Question moe29 Pass Labs 1 9th November 2004 06:48 AM
Pearl Phono Stage Coupling Capacitors (?) mirlo Pass Labs 4 24th July 2002 05:52 PM
Output capacitor for Pearl Preamp dkimble Pass Labs 4 17th July 2002 05:47 PM


New To Site? Need Help?

All times are GMT. The time now is 07:24 PM.


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