Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

DIY transformer and two-component epoxy adhesive
DIY transformer and two-component epoxy adhesive
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 14th February 2018, 09:11 AM   #31
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Quote:
Originally Posted by SemperFi View Post
What is the primary inductance? Is the magnitization (primary idle) current pretty high?
Are all the inductances as expected? Could a winding be the wrong way as to work against some of the other?
I don't think any windings is working against other.
B+ supply, bias supply and filament supply are all perfect, in terms of voltage. I use this PT in a real SEUL/SET amplifier, and it sounds great (probably my best sounding amp).

I measured the inductances (primary and also leakage) when I built it, and it seemed ok to me.
I'll measure it again today and post the exact value.

The idle current is something close to 90 mA (the amplifier is a monoblock). But, as already mentioned, the buzz is still there even when no loading at all.

There's some window height available (probably around 2 mm), and I'm using a split bobbin [primary/shield/bias] on one side, and [HV sec/filament sec] on the other.
I could unwind the top windings, and add some more turns to all, to lower the magnetization... but I probably won't get below 1.1T.

Of course this is quite a bit of work, so I was trying to avoid that if possible.
  Reply With Quote
Old 14th February 2018, 11:44 AM   #32
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Quote:
Originally Posted by TonyTecson View Post
like so....
Nice finish
  Reply With Quote
Old 14th February 2018, 05:23 PM   #33
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Primary inductance is 5 H at 100 Hz.

Would you un-wind and try to add some more turns?
Probably I would only be able to get 1.2T or little less.
No much winding window left.

Last edited by Elerion; 14th February 2018 at 05:50 PM.
  Reply With Quote
Old 16th February 2018, 08:05 PM   #34
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
So, enough talk. This required work
I unwinded and added 76 more primary turns.
Magnetization should have drop to 1.2T.
I've put everything together again, and after some hours of careful work , I just tested it, and...

Partial success.
It's still buzzing, but it seems to be a bit more quiet.
Perhaps 5 dB less (according to a crude sound meter app run on my phone, just next to the core, with the same exact mounting and on the same surface).
Now I need to be close to it to be able to hear it clearly.
I even have some winding window left,... maybe I could get down to 1.15T, but unwinding it again is something I just can't think about right now

As a curiosity, I measure the magnetic field before and after the modification.
At 30 cm, it was above 2mT from the front, and about 1.2mT from one side.
Now, it is lower. 1.6mT from the front, and 0.85mT from one side.
I suppose this makes sense.

I'm still using the same stiff 1.4mm wire for filament winding. I wanted to play with a single variable at a time. I could try to replace it with bifiliar 1mm. But many hours seem to be required to get a perfect result (at least two more times taking aways the laminations, and putting them back together )
  Reply With Quote
Old 16th February 2018, 09:26 PM   #35
SemperFi is offline SemperFi  Wake Island
diyAudio Member
 
Join Date: Jan 2002
Location: nowhere
Good job keep it up. It will be interesting to see your conclusion to what was required to reach your satisfactory xfrmr.
  Reply With Quote
Old 16th February 2018, 09:28 PM   #36
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
DIY transformer and two-component epoxy adhesive
i operate on a 0.6 to 0.8T in my tube power traffo builds, even for the higher quality cores, i seldom went beyond 1Tesla...
__________________
planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
  Reply With Quote
Old 17th February 2018, 08:35 AM   #37
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Before this one, I made a small PT for a preamplifier, with regular non-GOSS laminations, at 1 Tesla. It is quiet. So for this bigger one, being GOSS, I felt confident, so I targeted to 1.4 T.

Even at two meters distance, in complete silence, I can hear the buzz clearly.
It is not very annoying, but it is there, so I'm going to try to improve this further.

I'm testing the transformer like shown in the picture. No bells, no wedge, no pads. Just four bolts and those metal pieces (which I don't know their names in English) to make pressure along the short laminations sides.

Could a bad electrostatic shield or not perfectly insulated bolts make the transformer buzz? I think I've done it right, but just to know.
Attached Images
File Type: jpg new.jpg (304.0 KB, 64 views)
  Reply With Quote
Old 17th February 2018, 09:09 AM   #38
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
DIY transformer and two-component epoxy adhesive
if your electrostatic shield shorted out, you will see smoke come out....
otherwise no worries....
__________________
planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
  Reply With Quote
Old 17th February 2018, 09:16 AM   #39
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
DIY transformer and two-component epoxy adhesive
@Elerion, i am looking for a plastic bobbin similar to yours, 2.25 inch center leg and 4 inches stacking height, do you have them in your place?
__________________
planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
  Reply With Quote
Old 17th February 2018, 09:39 AM   #40
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
@TonyTecson, what a HUGE beast!

What EI size is that? EI-171?
I can get EI-150 and EI-180, and I think EI-174 (5,8 cm center length, which is a little bit bigger) but that one I need to ask. Is this one OK for you?
For EI-180 there're bobbins for up to 12 cm stacking height, so probably there will be bobbins the height you need. Just tell me if EI-174 is good for you, or not, let me ask, and I'll come back with some news in several days time.
  Reply With Quote

Reply


DIY transformer and two-component epoxy adhesiveHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Transformer epoxy or fill for diy potting Masonstorm Power Supplies 11 16th January 2018 04:48 PM
adhesive/epoxy for the amp nonprof Car Audio 11 2nd September 2015 06:09 AM
Conductive epoxy john dozier Parts 18 30th December 2010 05:30 AM
Epoxy or PVA Mos Fetish Multi-Way 2 4th February 2006 10:57 PM
Audio Note DAC KIT1.2 component list and power transformer spec PTSOUNDLAB Digital Source 2 13th May 2003 06:55 AM


New To Site? Need Help?

All times are GMT. The time now is 12:44 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki