Salas hotrodded blue DCB1 build - Page 171 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 March 2012, 05:19 PM   #1701
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
I'm using 60VA 15-0-15 with Salas Shunt Reg and it runs perfectly cool.

30VA 9-0-9 also ran cool with a simple CRC filter into LM317.

My original construction was 15VA 9-0-9 with CRC.

Try them all, you'll be hard pressed to hear the difference.

Last edited by KatieandDad; 5th March 2012 at 05:21 PM.
  Reply With Quote
Old 5th March 2012, 05:20 PM   #1702
diyAudio Member
 
Join Date: Jan 2007
Thank you Andrew.
The Selectronic R-Cores are a bit under-rated in terms of VAs but I too doubt they'll handle that much current.
I should have a 50VA toroid around here somewhere but perhaps it's more convenient to just drop the current. Will make heat management easier as well.
__________________
"You have a hierarchy: a mathematician, a physicist (which is a failed mathematician), and an engineer (which is a failed physicist)." - Andrew Jones
  Reply With Quote
Old 5th March 2012, 08:43 PM   #1703
diyAudio Member
 
oneplustwo's Avatar
 
Join Date: Apr 2009
Location: San Francisco
What other grounding requirements are there? I need to ground the transformer shield and the earth ground from the IEC.

Are the RCAs supposed to be isolated from the chassis or do they get grounded to the chassis as well as go to the volume pot?

Quote:
Originally Posted by Salas View Post
And grounded along with the bottom plate of course. Did you get its DC conditions measured yet? Running well?
  Reply With Quote
Old 5th March 2012, 08:51 PM   #1704
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
Even at HOT ROD 600mA Plus, the transformer should run cool. If you are running at an insane 600mA the 15-0-15V transformer is only running at 1A (Max) ie 30VA.

There are loads of arguments about the choice of transformer but at 30VA NOTHING should be running even vaguelly warm with a 50VA transformer. .
  Reply With Quote
Old 5th March 2012, 08:52 PM   #1705
CR500 is offline CR500  United States
diyAudio Member
 
Join Date: Nov 2010
I'm sure this has been covered and recovered, I just can't remember.

I have to choose between a 10k and 50k pot.

Any suggestions?

Currently running a 20k motorized (cheap version of the Alps) but want to try a different one which is only offered in the two other values.

Hopefully, one of these days I'll be building a B2 (as soon as the design is available)!

Thanks!!
  Reply With Quote
Old 5th March 2012, 08:56 PM   #1706
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
I found 50K Log B to be the best.
  Reply With Quote
Old 5th March 2012, 09:06 PM   #1707
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Jfets have high input capacitance and it might be best to stay lower than 50. I know it is very wideband buffer, but Mr Miller will come knocking if not careful.
  Reply With Quote
Old 5th March 2012, 09:11 PM   #1708
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
For the sake of a few dollars, try 10K and 50K. Take your ears for a listening test.
Try cheap pots to prove theory and then buy expensive NOBLE or ALPS pots.
  Reply With Quote
Old 5th March 2012, 09:56 PM   #1709
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by CR500 View Post
I'm sure this has been covered and recovered, I just can't remember.

I have to choose between a 10k and 50k pot.

Any suggestions?

Currently running a 20k motorized (cheap version of the Alps) but want to try a different one which is only offered in the two other values.

Hopefully, one of these days I'll be building a B2 (as soon as the design is available)!

Thanks!!
This circuit has been designed to have optimum bandwidth with up to 20K ish pots. 50K is not recommended both technically and subjectively. In case you insist, substitute the parallel input resistors from 220K to 560K.
  Reply With Quote
Old 5th March 2012, 09:58 PM   #1710
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by oneplustwo View Post
What other grounding requirements are there? I need to ground the transformer shield and the earth ground from the IEC.

Are the RCAs supposed to be isolated from the chassis or do they get grounded to the chassis as well as go to the volume pot?
The RCAs must be isolated, they have their own ground path to the PCB. Ground the IEC's earth prong near it to chassis with a short cable.
  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
dcb1 buffer with shunt reg. merlin2069er Swap Meet 0 3rd August 2010 05:25 PM
F2 and DCB1 parts selection - please advice! DQ Pass Labs 6 25th November 2009 03:20 PM
Y B Blue - how blue LED improves the CD playback Peter Daniel Digital Source 176 25th September 2003 07:40 AM


New To Site? Need Help?

All times are GMT. The time now is 11:52 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