Pearl Two - Page 78 - 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 29th July 2011, 11:56 AM   #771
diyAudio Member
 
Join Date: Jan 2011
Location: Southeastern Pennsylvania
Thanks

Also, I was thinking of using this PS:

Power Supplies, Power Supply, Bench Supplies, Transformers
  Reply With Quote
Old 29th July 2011, 11:22 PM   #772
diyAudio Member
 
richluvsound's Avatar
 
Join Date: Sep 2010
Location: LONDON
Hi Andy or Nar ,

would this be a good starting place for a PSU ? /www.quasarelectronics.com/velleman/k8042-symmetric-1a-power-supply-kit.htm

Thank you , Rich
  Reply With Quote
Old 30th July 2011, 08:10 AM   #773
nar is offline nar
diyAudio Member
 
nar's Avatar
 
Join Date: Apr 2002
Location: near the sea
Quote:
Originally Posted by richluvsound View Post
Hi Andy or Nar ,

would this be a good starting place for a PSU ? /www.quasarelectronics.com/velleman/k8042-symmetric-1a-power-supply-kit.htm

Thank you , Rich
Yes, I think it's a nice one to start with

Seems to be LM317 / 337 based, and ajustable. You'll only need to add xformer.

For later upgrading, I suggest to use either a shunt reg as the one seen with the Salas Buffer, or a symmetric one based of the Pearl original PSU, like below.

Click the image to open in full size.

Click the image to open in full size.

I use this power supply with a new UGS preamp, it is very stable, dead quiet, excellent regulation, provides excellent sonics. Layout takes care of ground lines that have a "star" like pattern, this helps to lower the noises created in ground nodes.
I'm very happy with those supplies They can virtually be used on any voltage, with small resistance adjustments. I plan to use it again but @ 30V for upgrading of my Aleph Ono clone

Best,

nAr
__________________
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...
  Reply With Quote
Old 30th July 2011, 09:21 AM   #774
milosz is offline milosz  United States
diyAudio Member
 
Join Date: Oct 2006
Default Pearl 1 channel imbalance

RE: 9 db difference left / right when using Dynavector 10x5, not seen with V15 -III

I think the issue has to do with differences in gain between the JFET input stages, which, for some reason is exaggerated when using the moving coil Dynavector (even though it is a moving coil, 10x5 is a 'high output' MC,it has a 2 mv output, not much lower than the Shure) Although the Dynavector has an output voltage similar to the Shure, I bet the CURRENT is much lower. (Although maybe I am NUTS, who knows)

Using a signal generator as input, I measure about 1 dB more gain in LEFT channel vs RIGHT

Anyway - the parts I have in this Pearl were a bag of parts assembled by a guy who never got around to building it; I bought the whole kit of parts, less transformers and chassis, DC umbilical, etc.

In this kit, the JFETS (2SK178BL) all had their tops painted white with whiteout, and marked with a 2 digit number an a number of dots. I have no idea what these are- gain readings? Transconductance? 'ON' resistance?

Should I have use these numbers in some way? Look at the schematic area, below, I have noted the numbers written on each FET in BLUE for Left, RED for right- should I combine these in some different order?
Click the image to open in full size.

PHOTO OF RIGHT CHANNEL FETS
Click the image to open in full size.

PHOTO OF LEFT CHANNEL FETS
Click the image to open in full size.
  Reply With Quote
Old 30th July 2011, 09:26 AM   #775
nar is offline nar
diyAudio Member
 
nar's Avatar
 
Join Date: Apr 2002
Location: near the sea
You should measure the V drop on each source R, and calculate X 4 resulting idle current for the quad. Then, same measures on the other channel. if you have current imbalance it could explain the mismatch with a particular cartridge.

If the jfets are well matched, they should at +/- 0,02 mA between the quad. And stereo quads should behave the same ...

Hope it helps.

nAr
__________________
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...
  Reply With Quote
Old 30th July 2011, 09:44 AM   #776
milosz is offline milosz  United States
diyAudio Member
 
Join Date: Oct 2006
Yeah that might be it. I guess I could measure the current for each FET and then use matrix alegbra to work out which transistors could be used in each quad to give the closes match between the two channels, or use some brute force recursive thing in Excel to figure which two sets of four to use. Hate to unsolder a bunch of FETs, I hate unsoldering. Never looks as nice afterwards. But this could be it.
  Reply With Quote
Old 30th July 2011, 09:45 AM   #777
milosz is offline milosz  United States
diyAudio Member
 
Join Date: Oct 2006
Default THANKS!

-oh, I forgot to say THANKS!
  Reply With Quote
Old 30th July 2011, 10:05 AM   #778
diyAudio Member
 
richluvsound's Avatar
 
Join Date: Sep 2010
Location: LONDON
Default SSLV1.1 BiB

Hi Nar ,

got a PM from Salas regarding PSU . This is a design you mentioned above .
. Very versatile and a proven design . I have B1 boards and the Pearl kit ,so building something that can power both would be good practice . I also like the idea of being able to use it for a new Aleph amp later on .

Are the PCB available do you know ,or anyone know ?

thanks , Rich

BTW, I also forgot to say thank you for the help .... sorry !

Last edited by richluvsound; 30th July 2011 at 10:08 AM.
  Reply With Quote
Old 30th July 2011, 10:21 AM   #779
nar is offline nar
diyAudio Member
 
nar's Avatar
 
Join Date: Apr 2002
Location: near the sea
Quote:
Originally Posted by milosz View Post
Yeah that might be it. I guess I could measure the current for each FET and then use matrix alegbra to work out which transistors could be used in each quad to give the closes match between the two channels, or use some brute force recursive thing in Excel to figure which two sets of four to use. Hate to unsolder a bunch of FETs, I hate unsoldering. Never looks as nice afterwards. But this could be it.
You could also slightly vary R Source to get more precise currents between the quads. Even if it's practical, in theory it's not as good as one could think, plus it induces unsoldering too

I would suggest you use patience and unsolder carefully the 8 jfets, then testing them to know their real IDSS. If needed, you can mix them with some new ones that would have a good matching value. K170BLs are becoming rare and prices go up nowadays.

Quote:
Originally Posted by richluvsound View Post
Hi Nar ,

got a PM from Salas regarding PSU . This is a design you mentioned above .
. Very versatile and a proven design . I have B1 boards and the Pearl kit ,so building something that can power both would be good practice . I also like the idea of being able to use it for a new Aleph amp later on .

Are the PCB available do you know ,or anyone know ?

thanks , Rich
I thinks Salas rather prefers using a shunty than the design I attached My mistake, if I recall properly the B1 has more than a layout, original boards don't have Salas PSU, and there is a DCB1 version that has the shunt built in ... not sure what you want to use here

Quote:
Originally Posted by richluvsound View Post
BTW, I also forgot to say thank you for the help .... sorry !
No problem

nAr
__________________
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...

Last edited by nar; 30th July 2011 at 10:32 AM.
  Reply With Quote
Old 30th July 2011, 11:48 AM   #780
diyAudio Member
 
richluvsound's Avatar
 
Join Date: Sep 2010
Location: LONDON
Default Post 773 !

Nar , thank looks straight forward enough .... are there PCB's for this ?

Rich
  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
Another diy-pearl... lykkedk Pass Labs 18 15th June 2007 04:44 PM
ono or pearl PCB's mantisory Pass Labs 1 28th September 2006 11:12 PM
Pearl need help dzkh63 Pass Labs 1 26th September 2006 03:16 PM
WTB: Pearl PCB aire Pass Labs 1 26th February 2006 10:51 AM


New To Site? Need Help?

All times are GMT. The time now is 05:38 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