4-1000a se subwoofer amp

[nhuwar]

Last night I sent sparky813 a pm asking about winding a output transfomer and he and I thought our corrispondence would be of instrist to the fourm also please feel free to add.

This is the message:

I was curious where you got most of you info on winding ot's?

I think I'm going to try tackling one in the near future and was
wondering if you could give me some pointers?

The questions I also have for you is how did you figuare how many
turns you would need to get the right impedance.

The other thing was in what order did you wind it pri first on and
then sec our vise versa.

Thanks Nick


Hi Nick, I will try to get some info together for you. I used an audio
design handbook that is no longer in print. The transformer equations are
fairly basic if you are O.K. with math. Beyond that, you need a wire table
to select the proper wire size for the current, etc. Single ended
transformers are more difficult since the iron has to be gapped. Do you
have some laminations yet? Sometimes you can salvage lams from an old power
transformer. I bought new, but minimum was about $150 so it was pricey. I
will keep your email, and try to respond with some details. I could do this
on the DIY website also. Sparky

[nhuwar]

I'm winding one for a single ended amp but I'm going to build it in the parafeed configuration. Also yes I have laminations from a power transformer out of a very large online ups. I havent said anything on the forum because they get kind of negative you know like it can't be done when you start to talk about doing anything with large power grid tubes. Anyways I wont to wind this xfmr for a 4-1000a yes thats not a typo.
I'll attach a pdf that has kind of gotten me started even though it's push pull


""If any of you moderator are in here how can I attach this pdf it's over 102k""

[nhuwar]

You should post that on the website, it is very intersting. I will read
through it carefully. I have a 4-1000 linear grounded grid amplifier for
ham radio. I don't think tetrodes are the first choice for audio. The
first thing I saw right off the bat, is that their xfmr is bifilar wound.
It is extremely difficult to get dielectric with this configuration.
MacIntosh has bifilar wound OPT's and they fail. The turn to turn voltage
is too high as the insulation gets old. It looks like in your IRE design,
they use .014 thick insulation. Most wire, I use now has thinner
insulation, even though some of it is "double dipped" I did some dielectric
tests and some of the wire broke down below 2000vac. My rule of thumb is
100v turn to turn maximum, when winding a transformer. I know this is way
conservative, but in 40 years of winding thousands of transformers, I have
never had a dielectric failure, not even one. Thanks for the attachment.
Sparky

If I recall right and by what I read in the pdf the bifilar is used for high frequency responses correct me if I'm wrong. Also reading that pdf and seeing that configuration of the windings I to thought arcing would be a problem but it said that teflon insulated wire was used which seams even stranger. But anyway I was thinking of a frequency span of 20 hz to 120 hz a good tube subwoofer amp.
I have the tube and a 5kva 50 pound e core in my garage I even have a big plate transformer for it.

If it's ok with you I will post this stuff and cut and paste our correspondence.
I did find this site that has info on how wind output transformers that I'm currently using let me know what you think .
Heres the site address http://www.geofex.com/Article_Folder...es/xformer.htm
I will also put up the pdf hope I dont get in trouble for it I payed $35 for it on ieee website that price is extortion if you ask me.

Nick


Hi Nick, I used to have a lot of IRE books, but I may have thrown them
away. Too bad. The bifilar and interweaving is for high frequency. You
could wind your xfmr just like a power xfmr for the subwoofer frequencies.
The investigation and things you are doing are of universal interest to the
DIY audio site so, I think you should post there, also.
Sparky