Problems with PT325.2i - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 10th October 2012, 11:13 PM   #21
diyAudio Member
 
Tom Bavis's Avatar
 
Join Date: Jun 2002
Location: Macedon NY
You might compare with an ordinary DMM (non-RMS) to see how bad the waveform is - they'll agree at lower levels but diverge near saturation as the waveform gets more peaked.
  Reply With Quote
Old 11th October 2012, 01:00 AM   #22
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
Here's the comparison between the Musical Power Supplies PT275 V2 and the Hammond 270FX. The excitation current of the Hammond was much higher than expected. In both transformers, the excitation starts out pretty linear, then takes off after ~100VAC. Both transformers are edgeing into saturation at high input voltage. I can see now why the Hammond has a rep for buzzing and heating up...
Attached Images
File Type: jpg xfmr.JPG (47.2 KB, 36 views)
  Reply With Quote
Old 11th October 2012, 05:02 AM   #23
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
^how about extending to say 180 volts? only goes to show that the Hammond has fewer turns than the china job....
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 11th October 2012, 05:47 AM   #24
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
Why? These are only 115/120V transformers.
  Reply With Quote
Old 11th October 2012, 05:54 AM   #25
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
yes, but it is interesting to find if the 2 curves will ever meet at some point...180 is not too high to cause saturation if testing only for a few minutes or even seconds...when they meet it will mean that the hammonds are using better quality irons...

heating up at idle and buzzing under load are two different things...
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 11th October 2012, 06:23 AM   #26
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
You can try it if you want to - I'm done.
  Reply With Quote
Old 11th October 2012, 06:27 AM   #27
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
no problem, so from your results, the china traffo is actually better than the Hammond traffo......we can stop at that...i would also bet that the china traffo has a higher primary dc resistance than the Hammond indicating that it had more primary turns to explain the lower idle current....
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 11th October 2012, 10:31 AM   #28
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Yes, both transformers are already gently entering saturation at below their rated voltage. Adding a secondary load will help, as the effective primary voltage will drop due to resistance.

It would be interesting to compare an expensive transformer, such as a Sowter.
  Reply With Quote
Old 11th October 2012, 05:36 PM   #29
diyAudio Member
 
Tom Bavis's Avatar
 
Join Date: Jun 2002
Location: Macedon NY
I test transformers at 144V 60 Hz (20% high) as a quick check of 50 Hz capability - if current rises rapidly with voltage, it isn't good for 50 Hz. The Hammond isn't rated for 50 Hz so has fewer primary turns. 10% more turns or 20% more core area is required for 50 Hz to give the same core flux as at 60. 10% more wire either way... there ain't no free lunch.
  Reply With Quote
Old 11th October 2012, 06:57 PM   #30
diyAudio Member
 
wrenchone's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
As a note, both transformers were tested at 60 Hz, and the PT275 was tested using its 120V tap - a best-case scenario. Both of the transformers are wound for 115V service only. I have heard that the 115/230V Hammonds are better quality, but I don't have one around to test this. All the rest of my power suppply iron is OOS. It might be interesting to take one of my old Fisher power transformers and subject it to the same test. I also have some old Halldorson iron that might be worth a try.
  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
energy veritas 2.2i crossover project sckramer Multi-Way 72 8th August 2014 10:31 PM
energy veritas v2.2i crossover diagram sckramer Construction Tips 0 3rd January 2011 06:05 PM
115v conversion fro 230V Cambridge Audio CD4 and Dacmagic 2i taskerc Digital Source 4 7th February 2006 07:02 PM
Cambridge Audio DacMagic 2i repairs query Fizzy Parts 3 11th January 2006 07:54 PM
Crossover Kappa 9.2i II Normi Multi-Way 1 27th October 2004 11:59 AM


New To Site? Need Help?

All times are GMT. The time now is 04:29 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