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 5th March 2010, 12:00 PM   #1001
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by sugden View Post
Will try adding more 68R in parallel to it, once I received Alps 20k volume pot from RS. Will report back back the out come. Right now can I test DCB1 without the volume pot? connect to my system Cambridge audio C840 CDP and Mcintosh MC240 power-amp driving JBL 4310. Because Mcintosh MC240 input come with volume control.
Of course you can when there is another volume pot in the chain. How much is your voltage after rectification? Maybe its a bit low? In general use as much current as it can allow the Mosfets not to feel too hot to touch. If having sinks, more is allowed.

Also you can try this cheapo. Plays rather well.
  Reply With Quote
Old 5th March 2010, 12:23 PM   #1002
Tea-Bag is offline Tea-Bag  United States
not politcally affiliated
diyAudio Member
 
Tea-Bag's Avatar
 
Join Date: Feb 2006
Location: Kennebunk
Blog Entries: 7
sudgen,
sounds like a nice system.
__________________
Salas Boards 2014 #1 Boards shipping |F5TC board and power supplies available PM | DCB1 boards and kits available PM
  Reply With Quote
Old 5th March 2010, 12:37 PM   #1003
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by AndrewT View Post
Hi,
the 68//68 with just 1.6V across it is passing just 47mA through the CCS.
The two B1 stages may be taking Iq~8+8mA, the shunt circuit could be taking 12mA. That leaves just 19mA passing through the shunt FET.
That may be a bit low.
Experiment with adding a further 68r to make three in parallel and maybe a fourth 68r in parallel. Each 68r passes ~24mA through the CCS.
Circa 50mA per rail would leave maybe 30mA per rail to each shunt Mosfet since each side uses 20mA more or less for 2 channels half B1, & rail CCS LEDs, Vref. That is about 0.3W on each shunt one and 0.35W on each CCS one assuming 7V in-out. A 22.6R (68//68//68) for 75mA CCS in his Rset Vdrop case you recommend, will still be rather safe for 0.525W on a bare TO-247 if the ambient is average. A touch test will quickly say.

Quote:
Originally Posted by woodturner-fran View Post
Mine definitely sounded better with about 10R in the place of the 68//68

Fran
200mA is working the Mosfets better indeed, they pick up Ygfs at that area. But it takes a fully sinked DCB1 construction...
  Reply With Quote
Old 5th March 2010, 12:59 PM   #1004
diyAudio Member
 
Join Date: Dec 2005
Location: Singapore
Quote:
Originally Posted by Salas View Post
200mA is working the Mosfets better indeed, they pick up Ygfs at that area. But it takes a fully sinked DCB1 construction...
Heat sinked into the chassis should suffice for 200mA (~8R) right?
  Reply With Quote
Old 5th March 2010, 01:07 PM   #1005
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Quote:
and the rest of the information we need for this to help us decide?
What else do you want Andrew? I did post this here but I'm sure its buried back in the thread. ..... I'll see if i can find it

Fran
  Reply With Quote
Old 5th March 2010, 01:10 PM   #1006
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by pengboon View Post
Heat sinked into the chassis should suffice for 200mA (~8R) right?
Yep. I have done that with up to 36V single shunts for phono, which is more dissipation. Even in small cheap chassis. Is your chassis floor a bit thick?
Attached Images
File Type: jpg SalasMC.JPG (505.7 KB, 674 views)
  Reply With Quote
Old 5th March 2010, 01:10 PM   #1007
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Taht post is here:

Building a symmetrical psu B1 buffer

and from the next post by Salas:

Quote:
Correct. We know from the shunt only threads that those IRFP devices pick up on their gfs curves around 200-250mA, and that subjectively it can be noticed. We knew it from the phono thread too, you confirm that the CCSed Jfet follower can benefit too. Next station is 3A, but it takes a power station too.
Fran
  Reply With Quote
Old 5th March 2010, 01:23 PM   #1008
cedricb is offline cedricb  Europe
diyAudio Member
 
Join Date: Jan 2008
just off-topic, for the IC: PCB to RCAs, volume control, etc.

Can I use this coax cable? NEXANS|RG179BU 100M|CABLE, COAX, RG179BU, PER M | Farnell United Kingdom ...it has low capacitance and it's copper with silver coated
This cable has been recommended by this site
  Reply With Quote
Old 5th March 2010, 01:33 PM   #1009
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Normal RG179 never betrayed me. That one may shine indeed. You can see some RG179 in another photo when with the HMC perf for my DL160 then.
Attached Images
File Type: jpg HMC.jpg (312.3 KB, 627 views)
  Reply With Quote
Old 5th March 2010, 02:08 PM   #1010
cedricb is offline cedricb  Europe
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by Salas View Post
Normal RG179 never betrayed me. That one may shine indeed. You can see some RG179 in another photo when with the HMC perf for my DL160 then.
thanks a lot @Salas, I'll buy this one! ;-)
  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
New-building of my B1 buffer Babowana Pass Labs 328 20th February 2010 01:14 AM


New To Site? Need Help?

All times are GMT. The time now is 11:18 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