• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Who makes their own OPT around here?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
TonyTecson

TonyTecson

Member
Joined 2003
the 2 irons at the right are output traffos, it has a 1" square core and uses Z11(M6 equiv.) core, design by YVESM....

IMG_0916.jpg

6LU8009.jpg
 
T

tryonziess

Member
Joined 2007
There is a website in Germany about a fellow who built a nice 160 watt GU50 PP amp and he posted a schematic of the trannys he wound up. The problem is finding core laminations here in the U.S. I have done quite a bit of searching and purchasing a small quantity of material, enough for say six units, is really hard to come by. I can not even source the raw sheet stock for silicon steel. Most of this stuff is used overseas.
If you are building anything over 100 watts your choice of stock transformers is pretty thin, especially for impedances for the GU50 and cheap sweep tubes.
I like the idea of building your own transformers. You can tailor them to your exact specifications. If only there was a good source for quality laminations.
If you salvage the steel from old discarded transformers you have no idea what grade of material you are getting. It seems the steel quality is a very important aspect of good output transformer frequency response.
Any good sources you may have I would like to have.
Thanks Tad
 
rvrazvan

rvrazvan

Member
Joined 2010
tryonziess said:
There is a website in Germany about a fellow who built a nice 160 watt GU50 PP amp and he posted a schematic of the trannys he wound up. The problem is finding core laminations here in the U.S. I have done quite a bit of searching and purchasing a small quantity of material, enough for say six units, is really hard to come by. I can not even source the raw sheet stock for silicon steel. Most of this stuff is used overseas.
If you are building anything over 100 watts your choice of stock transformers is pretty thin, especially for impedances for the GU50 and cheap sweep tubes.
I like the idea of building your own transformers. You can tailor them to your exact specifications. If only there was a good source for quality laminations.
If you salvage the steel from old discarded transformers you have know idea what grade of material you are getting. It seems the steel quality is a very important aspect of good output transformer frequency response.
Any good sources you may have I would like to have.
Thanks Tad
Click to expand...

There are a few things i know about laminations:
Silicon steel is brittle. You can see cristals them.
Oriented grain has a matte gray-ish apparence.

You can use an L-meter in order to find out what type of material you have. Wind 100 turns or so and find the inductance.
 
P

pieter t

Disabled Account
Joined 2009
tribute-audio.nl
Tad,

I really don't understand you US guys!
There is more and better than EI laminates!!
Of course I mean c-cores.
Let me help you; look for alpha cores in your home country.
You can buy online (no minimum quantity) for instance a 300 watts GOSS M4 c-core for some 15 dollars.
They also stock the bobbins.
Apart from electromagnetic superiority of c-cores over EI cores (no, I don't go into discussion right now) it is much easier for the DIY'er to work with c-cores: you don't have to staple laminates, and it is much easier to experiment with airgaps.
I don't know how much they cost but I also saw mounting brackets.
Go ahead, say goodbuy to EI and bring USA transformer technology back to the good old days of McIntosh c-core output transformers!
 
fooeywuffle

fooeywuffle

Member
Joined 2009
home.roadrunner.com/~t7/index.html
Most stuff I make is from recycled materials, so the terminals are # 12 house wire. Core size is determined by power and wire size. I always make them with large wire so not much IR loss, but this can get out of hand. Yes they are 3 mm, 1/8 inch, from edge. This just seemed about right. Didn't know it was a standard. The laminations have always been a problem, so used the old transformers which I had a huge amount of and friends who had even more! I think most of them were silicon steel, the crystallized kind. Most of the ones I used were close to 0.35 mm, but thinner ones would be better. As for frequency response, they usually came out flat, 0 DB, 15 cycles to 22 Kc. - 3 DB around 8 Cy to 50 Kc. Good enough for my old ears. Didn't seem to be much core loss. Never heated up. I was also told that burning them to clean up the laminations also messed up their magnetic properties, but I didn't see any problem. C cores are great and easy to use, but I prefer the Hypersil ones Like McIntosh used. The rest of them seem to be for 50 to 60 Cy power use. I made my first transformer in the 60s.
 
BudP

BudP

Member
Joined 2007
For those in the US who want to make OPT's with E/I laminations Thomas & Skinner is the best source for minimums and pricing. Typical order will be for 87 pounds of core. Typical price for 1 1/2" 0.014 M6 will be about $250 for 0.009 M3 about $450. You can download the T&S catalog here Thomas and Skinner - Transformer Laminations This is a 28 MB download.

Bobbins can be purchased from Ram Sales here Transformer Components Expect to spend some time contacting them, the guy who runs the order desk has periodic strokes and doesn't answer emails all that quickly. However, they will sell you one or two bobbins and they have the widest selection of sizes.

Bud
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom