Penultimate Zen transformer - 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 8th October 2010, 01:23 AM   #1
diyAudio Member
 
Join Date: May 2004
Location: Cranbrook BC
Default Penultimate Zen transformer

Hi, I bought someones completed amp that needs proper transformers to replace the ones that are causing hum.
I happen to have a new, old stock Toroid #767.302 on hand. Will this one work for me?
I don't know much about amp building but I think I have the nerve to remove the guts from this one and build a nice, new, larger case for this.
Any help with the transformer choice will be very greatly appreciated!
Brian
  Reply With Quote
Old 8th October 2010, 01:44 AM   #2
eyoung is offline eyoung  United States
diyAudio Member
 
eyoung's Avatar
 
Join Date: Aug 2007
Location: Sunny SC,USA 15 min south of Charlotte NC
Maybe it does not need a new tranny but maybe a thorough going through the grounding and filter cap scheme....maybe a few pictures and history of amp.

Regards.E
__________________
"Lead me not into temptation...I can find it myself."
  Reply With Quote
Old 8th October 2010, 02:12 AM   #3
diyAudio Member
 
Join Date: May 2004
Location: Cranbrook BC
Here are a few photos. If you need any more of anything specific let me know.
I know little of the history other than the claimed use of high quality parts.
Brian
  Reply With Quote
Old 8th October 2010, 02:14 AM   #4
diyAudio Member
 
Join Date: May 2004
Location: Cranbrook BC
Default Penultimate Zen

4 shots here...
Attached Images
File Type: jpg DSCN2353.JPG (184.5 KB, 428 views)
File Type: jpg DSCN2354.JPG (176.3 KB, 419 views)
File Type: jpg DSCN2355.JPG (171.1 KB, 403 views)
File Type: jpg DSCN2356.jpg (835.5 KB, 401 views)
  Reply With Quote
Old 8th October 2010, 07:31 AM   #5
alexcp is offline alexcp  United States
diyAudio Member
 
alexcp's Avatar
 
Join Date: Jun 2009
Location: Florida
Blog Entries: 37
Toroid #767.302 may not be ideal for this amp because of its 2x30v secondaries. Penultimate Zen has an onboard regulator (Q5 and associated circuitry in the original article) that provides 42 volts to the amp. The normal input to the regulator is 50 volts, but with 30v secondary you can only get 44-45 volts.

The regulator employs an IRFP044, which has the gate threshold voltage of 2-4 volts, depending on the specimen of the transistor. That is, under normal conditions the voltage at the gate of Q5 cannot be lower than 44-46 volts. In your case, it is 46 volts as provided by Z1-Z5 zeners. Add to this the 2-3 volts minimum drop on R17, and you get 50 volts as per the original design.

This amp dissipates about 100W per channel, so you would need a transformer rated at at least twice the total dissipation (400W for two channels) and with a 36 volts secondary.

If you want to use a transformer with 30 volts secondaries, you may try to replace one of Z1-Z5 with a lower voltage zener (e.g. 1N4732). This will reduce the output voltage of the regulator but will keep it regulating even with lower input voltage. It looks like the amplifier itself will not require massive adjustment if it is fed with 37 volts instead of 42.

The regulator provides the amp with some immunity to the poor filtering of unregulated supply, so I would not suspect the filtering, unless there is an obvious problem like a disconnected cap. However, the input wires and volume controls placed close to the E-I core transformers (and, I presume, rectifiers - I don't see them on the photo) may indeed be a source of hum.

Last edited by alexcp; 8th October 2010 at 07:53 AM.
  Reply With Quote
Old 8th October 2010, 03:44 PM   #6
diyAudio Member
 
Join Date: May 2004
Location: Cranbrook BC
Quote:
Originally Posted by nelsondog View Post
claimed use of high quality parts.
Brian
...I should mention the transformers used were deemed poor quality and thought to be the source of the 60Hz hum.
  Reply With Quote
Old 8th October 2010, 03:48 PM   #7
diyAudio Member
 
Join Date: May 2004
Location: Cranbrook BC
Just to be sure, Plitron model 117033201 would be the correct trans to use?
Attached Files
File Type: pdf Plitron1170XX201-1.pdf (137.5 KB, 19 views)
  Reply With Quote
Old 8th October 2010, 05:47 PM   #8
diyAudio Member
 
Join Date: Aug 2002
Location: Toronto, Canada
If I'm reading it correctly, 117033201 has 50VAC secondaries. That's too high.

Perhaps 117018201 (35VAC secondaries)?
__________________
We are fearless amplifier builders. A little heat doesn't scare us at all.
- NP 2002
  Reply With Quote
Old 8th October 2010, 06:24 PM   #9
alexcp is offline alexcp  United States
diyAudio Member
 
alexcp's Avatar
 
Join Date: Jun 2009
Location: Florida
Blog Entries: 37
1kW, 10A transformer is an overkill, and 50v secondaries would increase dissipation from 100W to 140W per channel. If you have a choice, a Plitron 757035201 or 087035201 would be better.
  Reply With Quote
Old 14th November 2010, 08:09 PM   #10
diyAudio Member
 
Join Date: May 2004
Location: Cranbrook BC
...just to verify, Plitron 087053201
500VA, Output V = 175 + 175, 1.43A.
Is this correct? I just want to be sure before placing an order.
  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
Penultimate Zen Transformer JamesHill Pass Labs 11 9th June 2009 06:54 PM
The Penultimate Zen Part 4 gchrist Pass Labs 7 26th August 2008 08:07 AM
Penultimate zen psu arlekin Pass Labs 1 30th January 2006 10:07 AM
Penultimate Zen Hybrid kristijan-k Pass Labs 48 11th January 2004 08:26 AM
Help with Penultimate Zen amp. Panelhead Pass Labs 3 30th December 2002 03:26 AM


New To Site? Need Help?

All times are GMT. The time now is 10:16 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