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CJ

Fender 6L6 Output Transformer
« on: October 30, 2009, 02:48:08 AM »
the ears said that it liked the fisher, the same ears say that this fender right here is junk.




so, .... :o


















































IT MUST DIE A SLOW AND PAINFUL DEATH!!!    ;D ;D ;D ;D ;D :D :D :D :D :D ;D
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php


CJ

Re: Fender 6L6 Output Transformer
« Reply #1 on: October 30, 2009, 04:34:04 AM »
parts is parts, thought they put another can underneath the end bells, but i was on crack.  :D



it was just this sh*tty epoxy compound from the back of a greyhound bus bathroom, 6 months old,  :o



somebody ran out of yellow mylar, so they stole some shipping tape from wallmart 99 cent bin,

they tried to fool us with the yellow paint, but we know better, right? uncle cj has taught us well, ;D





even the hookup wire is crap. just one blow from the maul, i swear, officer, i only hit it once!

but if snapped like a dry twig in a stiff desert breeze.




so,

 sec - pri - sec

no bi fi

no reverse

no balanced pri

no interleaving

crappy materials for potting

it is funny, when you see two dis similar materials used at once, it is usually a crappy design,

like wax and pottng compound, or paper and potting compound,

 or compound that locks everything into a solid block, you material engineers know what i mean? ???

these lams bend like soft butter even though they are .014 . you know what that means,

no grain structure what so ever, somebody went out to arkansas to mount a horse,

and they came back with the barn roof  instead!

you know what the cop said to the guy doing that horse?

"you two should get a barn,"   ;D ;D ;D ;D



« Last Edit: October 30, 2009, 05:04:04 AM by CJ »
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php

alexc

Re: Fender 6L6 Output Transformer
« Reply #2 on: October 30, 2009, 06:35:26 AM »
That's great to see there can be a physical reason for crappy sound in a cheaper traffo.

Glad I bought a good one for my super reverb build!
I ping therefore I am

emrr

Re: Fender 6L6 Output Transformer
« Reply #3 on: October 30, 2009, 10:21:58 AM »
can you put a year on that example?
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounded g

Biasrocks

Re: Fender 6L6 Output Transformer
« Reply #4 on: October 30, 2009, 10:41:58 AM »
can you put a year on that example?

It's most likely out of a older model Fender Super Reverb or Bassman

According to http://www.svvintageamps.com/dating.php

If it came out of a blackface amp

The code 606-431 indicates it was made by Schumacher (606), manufactured in 1964 (4) in the 31nd week (31)

If it came out of a silverface amp it could be 1974.

Mark
« Last Edit: October 30, 2009, 10:45:43 AM by Biasrocks »
http://SharktankPro.com

"I'd rather use an SPX90 than a UA plugin....." Joe Barresi

emrr

Re: Fender 6L6 Output Transformer
« Reply #5 on: October 30, 2009, 11:16:01 AM »
Thanks, didn't have my date code info here.  Good for people to consider.
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounded g

CJ

Re: Fender 6L6 Output Transformer
« Reply #6 on: October 30, 2009, 11:34:04 AM »
tghis is definately a silver face. i looked arounf for the original silver can twin output,

BUT I MST HAVE HACKRD IT ALREADY!  >:(                       :D

the old 59n bassman aka keef richard uses a really cool transformer, i think it is a 5/4 job.

If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php

AnalogPackrat

Re: Fender 6L6 Output Transformer
« Reply #7 on: October 30, 2009, 01:27:22 PM »
Interesting contrast with the Fisher.  Looks like the Fender is also laced 2x2.  Prepare for some potentially stupid questions...

1) What is the effect of more interleaving (p-s-p-s-p-s-p vs. s-p-s, for instance)?  Lower leakage inductance?  Better coupling?  Lower capacitive losses?

2) What do the reverse winding layers on the better Fisher OT improve?

3) Why would one manufacturer choose to put the first primary winding close to the core and another the secondary?

4) Other than being a PITA for dissection, why is epoxy worse than wax for potting?

5) What effect does core lacing have?

Just trying to get a handle on the design factors and tradeoffs.

A P
If it is to be, it is up to me.

Gus

Re: Fender 6L6 Output Transformer
« Reply #8 on: October 30, 2009, 01:46:02 PM »
Epoxy and other stuff used.

Material science stuff.  Expansion and contraction rates and distance moved vs temp.  Do the rates match if not say you have the transformer in a very hot car in the very cold or hot what might happen to the magnet wire?

little of topic

I have read but not tested a good potting material for guitar pickups is 20% beeswax and 80% paraffin

Also in microphones rate of movement of the backplate vs the PVC or PET etc

Re: Fender 6L6 Output Transformer New
« Reply #9 on: October 30, 2009, 03:09:09 PM »

It's most likely out of a older model Fender Super Reverb or Bassman

According to http://www.svvintageamps.com/dating.php

If it came out of a blackface amp

The code 606-431 indicates it was made by Schumacher (606), manufactured in 1964 (4) in the 31nd week (31)

If it came out of a silverface amp it could be 1974.

In my mind, that thing is a '74.

Remember if it came out of a blackface amp, it could have been a replacement.

The original part number of this trannie would have been a 125A7A. The 018343 would have been used in the Vibrolux or Pro in the 70s. 

It would have been a replacement for a brown/blackface Vibrolux, blackface Pro/Reverb or blackface Vibroverb. Also, it would have been a replacement for a brown/blackface Bassman.

http://www.unclespot.com/FenderXFMRchart.html

http://img818.imageshack.us/img818/4213/xformerxreferencelist.gif

Certainly not OEM in the '60s, IMO.
« Last Edit: November 22, 2011, 03:21:06 AM by fazeka »
"Kind of like going into Safeway at 4 in the morning and chugging a beer in the produce section; been there, done that." - CJ

"We're not making an atomic bomb, just cooking a few electrons." - PRR


CJ

Re: Fender 6L6 Output Transformer
« Reply #10 on: October 30, 2009, 09:21:33 PM »
they run a square stack of 1 and 1/4 inch, but the core tube is more like 1  and 5/16,

lap 2 just like AP said,

the more laps you use, the more of a gap the transformer sees.

so on some of the nickel stuff, the lap 5, or lap 6 so the do not saturate. most mains stuff is lap 3.

i will scan some pages on coil geometry and post them, with this new camera it will actually be readable.

wax, varnish, and paper insulation can all interact to form a dialectic between the layers.

plus the copper wire has a coating, and air, so you have a cap with 5 dialectics,

this means the fastest way to model it is to do experiments, but all that has been done,

so just copy what the best transformers do and avoid re inventing the wheel.

shugg wrote a 500 page book on insulation, if you want to fall asleep at night, read that book. 8) 



this looksj ust like the fisher, i might have to eat crow on the coil, but the lams still suck, :o
« Last Edit: October 30, 2009, 09:32:29 PM by CJ »
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php

AnalogPackrat

Re: Fender 6L6 Output Transformer
« Reply #11 on: October 30, 2009, 11:49:01 PM »
the more laps you use, the more of a gap the transformer sees.

so on some of the nickel stuff, the lap 5, or lap 6 so the do not saturate. most mains stuff is lap 3.

OK, so tradeoff is reduced chance of saturation at the cost of core losses due to the virtual gap?

Quote
i will scan some pages on coil geometry and post them, with this new camera it will actually be readable.

That would be cool.  All of my old electronics books are in boxes somewhere and I don't have anything transformer specific.

Quote
wax, varnish, and paper insulation can all interact to form a dialectic between the layers.

plus the copper wire has a coating, and air, so you have a cap with 5 dialectics,

this means the fastest way to model it is to do experiments, but all that has been done,

OK, I understand that.  Especially for a tube OT you need to avoid arcing over.  I can also see how the mechanical properties of a rigid potting compound could cause trouble with repeated heating/cooling cycles.

Quote
so just copy what the best transformers do and avoid re inventing the wheel.

Easy to say for a guy with his own winding setup and a brain full of transformer experience!

Quote
shugg wrote a 500 page book on insulation, if you want to fall asleep at night, read that book. 8) 

Falling asleep isn't a problem--STAYING asleep is.  I guess if I whacked myself over the head with it I could get both effects.

If it is to be, it is up to me.

clintrubber

Re: Fender 6L6 Output Transformer
« Reply #12 on: October 30, 2009, 11:54:42 PM »

CJ

Re: Fender 6L6 Output Transformer
« Reply #13 on: October 31, 2009, 12:17:44 AM »
Stevie Ray use to hammer his output, i'm jus sayin...

this thing is weird, here are some pics,







this is where it gets funky, the el84 had this as a bi-fi start/finish, but here, the wires are fused.

so either somebody fu*ked up the re job, or the assembler messed up, or they want low dcr.



so you think this thing is spliced all over the universe, but when you divide out these 2 wire winds,

it ain't so bad. oh, i think i get it, this is a 4 ohm winding, and you need max current, so twice wire,

doh!   :o ??? ::) :P :-[



if you dump too much solvent in the varnish tank, you can cook the wire insl, but they use  no varnish,

so maybe the wire itself, or something in the plastic insl,



this is nice shot unless your Joe, the Singin Janitor,


he can't carry a tune in a bucket, but he carries that bucket with pride,

yeah he's the man behind the mop, he makes everything sparkle and shine,

so as an audio xfmr geek, your goal is to get that first layer as close as human can get, not like this,

i smell a good transformer design that got sent offshore, might sound ok, but the wire, the lams,

the construction,

i'm jus sayin


now what?

Trident A/B range output, or a Peerless 6L6 output?

or a 50 watt fender concert outie, this was a 100 watter i believe,

i just got me a dose of hackin fever from the new swine flu vaccine,  ;D


« Last Edit: October 31, 2009, 01:45:26 AM by CJ »
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php

PRR

Re: Fender 6L6 Output Transformer
« Reply #14 on: October 31, 2009, 01:55:43 AM »
> What is the effect of more interleaving (p-s-p-s-p-s-p vs. s-p-s, for instance)?  Lower leakage inductance?  Better coupling?  Lower capacitive losses?

Yes, yes, no.

To a point: better high frequency response. Until the rising many-layer capacitive losses fight the declining leakage inductance.

And higher price.

It should be noted that for "speech band" low-NFB work, impedances up to several K (fender worked 2/4 6L6 at 4K/2K load) are fine without interleaving. I don't know which Fisher, but EL84 like 8K load and Fisher used a good slug of NFB: the hifi amp needs interleaving, Dick Dale didn't.

> Why would one manufacturer choose to put the first primary winding close to the core and another the secondary?

The core is grounded. A high impedance point laying against the core has highs sucked out. However the secondary is grounded (one end grounded and the other end of a speaker winding is far closer to ground than a tube primary winding). So unless you pack thick paper between windings, the "hot" ends of the primary are sure to be laying against groundy stuff (either core or secondary).

For a 4K winding aimed for over 6KHz and no concern about top-resonance messing your NFB, I'd say it does not matter one whit. What is easier for the winder? What gives a better mechanical build? How did we do the previous model?

The thin primary will wrap the corners of the bobbin better than the fat secondary, reducing DCR or allowing a few more turns in the same build. However the fat secondary may tend to moosh the fragile primary windings.

Fisher hifi 8K winding with 26dB NFB, the difference may be small but worth prototyping both ways. IAC the hifi will have more interleave, both primary-secondary and between the two halves of the primary.

> this is a 4 ohm winding, and you need max current, so twice wire

The number of turns is fixed, and for 4 ohms and limited bass response, you want a small number of turns.

But for mechanical stability you want whole layers.

I suspect they computed the "obvious" wire size, and it was awkwardly fat for bending or came out to like 3/4 of a layer.

Bifilar in a single winding allows the winding width to be adjusted independently from the number of turns and the DCR. Two strands of 0.707 diameter will come out 1.414 times wider for the same turns and same DCR. It is also thinner and easier to bend. But it adds significant cost. It is an odd thing to do for a geetar OT.

AnalogPackrat

Re: Fender 6L6 Output Transformer
« Reply #15 on: October 31, 2009, 08:00:20 PM »
Thanks for the detailed and interesting response, PRR.  I think I get most of what you said after reading a couple of times and cogitating a bit.  My education continues...

A P
If it is to be, it is up to me.


 

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