• Please note that there are a few updates and clarifications made in the Audiokarma Rules, mostly relating to advertising and the addition of the new "Paying it Forward" & "Giving back" forums in the AudioKarma Audio Marketplace section.

Altronics m1115 Output Tranny

J

JesusJones

Well-Known Member
So I finally have 2 of these transformers on the way here. All the way from Australia.

What makes them so special??.....

Well they can be used to make a 6v6 push pull amp. With ultralinear screen taps and all. FOR ONLY $13! each!!

They also claim to have a 30hz-20khz freq. response!

So I plan to build a SE (maybe ultralinear....??*opinions??) 6v6 gt amp. I have many of those tubes and power transformers that came with them. So the output trannies are the only real expense I'll have.

And by running them slightly cool I hope to get that bass down to 20hz.

And just a warning to anyone who wants some of these. Shipping ain't cheap!! 45$$$! Thats more than they're worth. But hopefully they are worth it :thmbsp:


Cheers,
Rudy

P.S. When they do arrive I will put one into a SE 6v6 amp I have now. And see how that sounds compared to the PA output transformer thats in there now.
 
Register to hide this ad
Well just incase you can't wait heres where I heard of them.

http://ozvalveamps.elands.com/optrans.htm

they used them for guitar. But theres 2 links in teh first paragraph and one of them takes you to a page where some one built a amp from them. With apparently worthy results.

I'm excited. I've wanted to build my own stereo tube amp for a while now. Bought a fisher 400 and I love the way it sings but, because I invested soo much $$ into it, I am weary to use it very often(haha if that makes sense) at least till I get my Varriac
 
Well I didn't wanna leave you hanging Kegger.

These transformers are OK and if I had paid 50$ instead of 90$ to get them to my door(stupid hidden fees) I would of been a very happy camper:yes:

And here are my impressions/test results:

Trying to get a 6v6gt in SE mode with 4k and 8k loads in triode mode sounded terrible. The mids were blaring and it just sounded too gainy. This could of been due to my poor gain stage. But I tried both a 12at7 and 12ax7 driving it and you get the same result.

I decided that for SE operation a 6v6gt had too much anode current.

So yesterday I realized I had 2 good 12au7s. And figured I could get maybe 1-1.5 watts running both halves in parallel 8k load.....Very surprising. It actually sounded pretty good. The bass was good. And the highs and mids were nicely balanced. All without NFB.

So my conclusion is that I should have bought maybe the 20 watt model. Then maybe it would have sounded better with the 6v6 gt.

But also don't forget that this Transformer can be set up for push pull. And I haven't tried it like that.

Would I suggest you go and buy these....No, since the 6v6gt test went poorly I'm kinda disappointed with my purchase.

But since I have the transformers and don't want to have wasted 90$ I'm gonna build a 3 tube 12au7x2 12at7 stereo amp. With efficient speakers it's actually very nice. I was just hoping for a bit more power. But oh well. Live and Learn :thmbsp:

Cheers,
Rudy

Edit: Oh and I'll get a picture for you tomorrow
 
Pictures as promised...just a little late :D


Thats a 12ax7 by the transformer. They really are rather small. And also some pictures of the 12au7 12ax7 stereo amp I'm building. It's almost done.



Cheers,
Rudy


P.S. Try not to laugh to hard at all my pencil marks. I realized after everything was screwed down that I should have flipped the board over after marking it......Woooops.
 

Attachments

  • IMG_0497[1].jpg
    IMG_0497[1].jpg
    52.3 KB · Views: 74
  • IMG_0498[1].jpg
    IMG_0498[1].jpg
    43.8 KB · Views: 52
  • IMG_0499[1].jpg
    IMG_0499[1].jpg
    65.3 KB · Views: 63
Good luck with your build!

BTW, I'm no expert, but I think ultra linear operation refers to a type of regulated screen operation of pentodes, of which a SE strapped 6V6 would have no use for...?

Or you could just make a PP, ultra linear 6V6 amp!

Also, unless you're a grounding master or that MDF is just a breadboard, be careful!

Best,

John
 
Wow those are quite small, to bad they didn't work out for the 6V6.

6V6 running single ended ultra linear makes quite a nice working amp..
 
Use them as parafeed transformers with your 6V6 in triode mode, a hammond 157g as plate load and 3uF parafeed cap, and be prepared to be amazed at the difference.
 
Well I got the amp together and working today.....Sounds even better in stereo. :D
Not super loud but loud enough to sound good.(and no NFB yet)


But I sort of like mach1's idea. I didn't even really know you could do that. But now that I've looked it up it makes lotsa sense. But also requires me to buy parts. Not something I like doing :P

This amp was really all about learning. And I probably will try wirring a Good testing 6v6 in ultralinear mode. And see if the results are still the same (very loud mids)


I have one question also. About the power supply I rigged up.

It's a SS bridge rectifier. Puts out 197 volts with no load. Then under load it drops all the way down to 177......I just don't understand how so much is being dropped. I thought SS had very low diode loss.

Also after powering down should the voltage begin to steadily drop....It goes down about 1 volt every 4-6 seconds. I tried that before the heaters warmed up. So there should have been nothing letting the capacitor bleed. Normal?? or garbage capacitor?

Cheers,
Rudy
 
Most of the drop is in the winding esistance in the transformer. It will be several times what you might think from the DC current and resistance measurements, since the peak current through the transformer is about 3 times the C output current. Download the PSU designer program from duncanamps.com and you can model the output of a power supply very closely.

Those transformers will probably work better in push-pull, since the DC current of a single-ended stage will saturate the core, reducing the inductance. In push-pull, the two DC currents are in opposite directions, so the magnetic flux cancels to near zero.
 
Well after experimenting some more, I decided I was going to go Push Pull. The transformer does MUCH better push pull. It had a nice wide requency response, clean deep bass and had no NFB applied.

I've also scrapped that peice of MFD and will be finding some sort of nice metal base that will get powder coated to look like stainless steel. So I can have a living room worthy amp.

Now I have just a couple questions before I can proceed :)

Since the push pull amp will have much more current running and draw much more heater current. My 12.6v filament transformer will not be able to provide enough current.(its rated 1.5 amps @ 12.6 volts) So is it OK to wire the 12.6 volt transformer in parallel with a different Power transformers 12.6v line???
OR If I used halves of the filament transformer could I get 3 amps into 6.3 volts?


And the Power transformer you saw before only puts out 200 volts DC peak. Which limits my power output alot. So I was wondering If you guys could guess what kind of power output this transformer has.

Its 670v CT

Its laminates measure 3 3/4 x 3 1/2 x 1 1/8 (L,W,H)
the actual winding 2 x 2 1/2 x 3 (L,W,H)

It originally powered 4 9 pin tubes (xs, 6ba6 6at6.....) and one 6v6 and a 5y3 rect.

Just any guesses as to whether or not something that size could handle roughly 140ma in current .

I look forward to your responses,
Rudy
 

Attachments

  • IMG_0500[1].jpg
    IMG_0500[1].jpg
    74 KB · Views: 27
Last edited:
I would expect that transformer to be good for about half of what you need - though it's physically larger than I'd expect.
 
Well lucky me. That wasn't the only power transformer I had for parts.

I remembered this beast I got for parts from a teacher of mine.

http://www.radiomuseum.org/r/philips_el6405_el_6405.html

I tried it out when I first got it. It had hum. And didn't have a "super" frequency response. So I never bothered with it.

But like I said lucky me :) It had 2 el 36 running push pull. Each el 36 draws 1.2 amps per heater. So that's plenty. As for current on the actual primary, not too sure...but judging from it's weight and size (5 pounds) I think it's a contender. And a quick look at the tube charts shows that a Pair of el 36s running class B at 44.5 watts would draw 200ma. Which only backs up my thoughts.

Dimensions of laminates are 1 5/8 x 3 1/4 x 3 3/4
Dimensions of Windings 3 x 1 7/8 x 2 1/2
W x L x H

Thoughts again :D ???
Thanks guys,
Rudy

Just a note. I really wanted to keep this project cheap and to do it with what I had collected over the years. So thats why I'm not rushing out to buy stuff, and keep asking so many questions. I really hope no one minds :yes: Also waiting for stuff in the mail is a drag :drool:



And Happy Thanksgiving to everyone celebrating today!

Edit: So I tried attacking this mathematicaly. The transformer had a .6 amp fuse. So .6amp x 125v = 75 watts then with all the heaters added up 3.6amp x 6.3v = 22.6 watts 75 - 22.6 = 52.4 watts and If it makes 350vdc then 52.4 / 350 = .149 amp :D very close.
 
Last edited:
Nope, not all of them. I'm gonna have to steal the phase splitter design from those schematics. I'm guessing they will work better than a single triode phase inverter.

Thanks for the links Mach1!
Rudy




And quick question for everyone.....A resistor between the HT and power stage......Big no no?? or OK?

Most of my transformers give me above 350 volts. I need 280. So I dropping resistor would be needed/used.


And if it's not a good idea. Anyone know what kind of things to look inside of for a 1:1 ratio transformer.:D Microwaves, Tv's, monitors......?


And another question(I have many questions :)..) I read one time that a center tapped rectifier can deliver twice as much current from the same transformer as a bridge rectifier. True or False?
 
Last edited:
I looked around lots and just thought about it logically and a center tapped full wave rectifier will NOT produce double the current.

I read the that it will give double current on Fun with Tubes. A nice website with some good info. But I will be emailing him to clear that up.

This on the other hand will give you double current...apparently
http://focus.ti.com/lit/an/slua121/slua121.pdf

Cheers,
Rudy
 
You must log in or register to reply here.
Back
Top Bottom