Crown Studio Reference I: beefing up the power supply - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 5th December 2009, 08:36 AM   #1
elac310 is offline elac310  France
diyAudio Member
 
elac310's Avatar
 
Join Date: Nov 2007
Location: Strasbourg
Default Crown Studio Reference I: beefing up the power supply

I've finally found an SR I to buy from the uS and I'm almost done with the conversion to 230V.

Since I had to put my hands in the amp, I was considering beefing up the power supply. The toroid transformer is among the biggest I've seen so far in a commercial amp so there's no worries on that side. I do not intend to replace the bridge rectifiers with fast diodes either.

Also because of the natural ageing process and to be on the safe side for the next few years, I see a good opportunity to replace the two 6800uF caps. Because of the limited space left, I could use a bank of smaller computer grade capacitors of 12x2200uF on each channel.

The current 6800uF caps are rated about 8-10A according to manufacturer datasheet and this is easily handled by any bridge rectifier of the uper range such as those currently installed in. But a bank of the caps I intend to mount would draw theoretically about 36A and the toroid can easily release a large amperage at firing up even though it would not reach that amount of current;

My questions, especially to those who are possibly familiar with this amp: 1) Would the bridge rectifiers (because of the way they are mounted I can't read their current rating or identify the part used but they're the size of classical 20-30A) and the PCB they are mounted on handle the extra surge current ? 2) anything else (especially possible surge limiters) I need to upgrade as well, besides perhaps the wiring between the PCB where the bridge rectifiers are mounted and the caps?

Thanks for any tips and advice.

Chris.
  Reply With Quote
Old 28th December 2009, 04:47 PM   #2
Account Disabled
 
Join Date: Oct 2008
Why you need to do that man?
  Reply With Quote
Old 29th December 2009, 11:47 PM   #3
elac310 is offline elac310  France
diyAudio Member
 
elac310's Avatar
 
Join Date: Nov 2007
Location: Strasbourg
Quote:
Originally Posted by microsim444 View Post
Why you need to do that man?
Because I found the original value a bit "short" 1) to handle the current needed by this amp; 2) to provide the energy required by fast musical impulses on medium and high frequencies.

As regards 1), contrary to my initial thoughts, I have ordered capacitors with "only" twice the current capacitance (and lower ESR) and that are not too large so that they can fit in lieu of the current ones (if someone is interested, I'll report back on this as soon as it's done); It could be that the reasonable value of the existing caps is one of the reasons for the extra-ordinary bass slam of this amp; I will thus not alter this element of the amp's personality and will avoid modifying anything else.[EDIT: the bass slam concerns the upper bass rather than the first one or two octaves]

On 2), in the meantime, I have now added 20uF MKP caps in parallel to the existing electrolytics: the amp has definitely a smoother sound on voices and certain accoutic instruments (used for instance on classical/ancient music). Until now, I usually had better experience with larger decoupling high voltage caps of up to 100uF than the 0,1uF or less that is sometimes recommended for the decoupling of power supplies in amplifiers (small values are probably OK for lower consumption circuits, e.g. preamps, digital circuits etc.).

Chris.

Last edited by elac310; 29th December 2009 at 11:53 PM.
  Reply With Quote
Old 18th April 2010, 05:54 PM   #4
OMF is offline OMF  Norway
diyAudio Member
 
Join Date: Nov 2009
Hi!

Currenlty I have 2 Studio Reference I in my set up. I would be very interested in you opinion of this "mod/upgrade"!

Thanks!

Best regards
OMF
  Reply With Quote
Old 28th April 2010, 12:50 AM   #5
diyAudio Member
 
Join Date: Feb 2010
Location: Bucharest
Send a message via Yahoo to Th3 uN1Qu3
There is a general rule on filter caps - any higher than 10000uF and the law of diminishing returns starts to apply.

10000uF caps would be a good idea. More, i don't think so. Anyway the only thing that larger caps will do in a class AB design is better transient reproduction, as the supply voltage sags less under momentary high load peaks. They will not magically bring more power or anything like that, but since this is supposed to be a "studio" amp they probably don't need to either.
  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
Beefing up the power supply whitelabrat Tubes / Valves 9 16th November 2007 07:23 PM
Shearne reference Phase 2 amp - capacitors for power supply. Organist Solid State 3 21st August 2007 04:18 PM
Reference Amp for studio exhausted mule Solid State 0 5th June 2006 05:39 AM
Any website reference for diy Audio Research REFERENCE amp and Manley Studio amp bmpa Tubes / Valves 4 19th April 2004 05:11 AM
Any information , website reference for diy Hi-End computer studio sound card? bmpa Digital Source 5 16th April 2004 04:57 PM


New To Site? Need Help?

All times are GMT. The time now is 10:48 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