Guitar Amps Output Transformer specs

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Hi all,
I would like to resume some informations about output transformers (I will open another thread on power transformers too), because I've found someone near me that can build it way cheaper than usual, so I can try different solutions for the same bucks.

Here is something I've found by now:

Dagnall C1998 38x38mm EI M6 core:
- 16-0 ohm secondary (parallel): 120 turns x 0.76mm
- primary: 2 x 620 turns x 0.45mm
- 8-16 ohm secondary: 35 turns x 1.18mm
- 4-8 ohm secondary: 25 turns x 1.18mm
- 0-4 ohm secondary: 60 turns x 1.60mm
All lead diameters are measured including the insulation on it.

Dagnall C2668 on 38x40mm EI M6 core:
- 0-4 ohm secondary: 60 turns x 1.76mm AWG13
- 1/2 primary: 620 turns on four layers x 0.45mm AWG26
- 4-8-16 ohm secondary: 25+35 turns x 1.18mm AWG18
- 1/2 primary: 620 turns on four layers x 0.45mm AWG26
- 0-16 ohm parallel secondary: 120 turns on two layers x 0.75mm AWG21

Dagnall C3070 32x60mm EI M6 core:
- 1/4 primary: 310 turns on two layers x 0.45mm AWG26 (B+ to half A2)
- 0-2 ohm secondary: 40 turns x 1.76mm AWG13
- 1/2 primary: 620 turns on four layers x 0.45mm AWG26 (B+ to A1)
- 2-4 ohm secondary: 20 turns x 1.76mm AWG13
- 4-8 ohm secondary: 25 turns x 1.76mm AWG13
- 8-16 ohm secondary: 35 turns x 1.76mm AWG13
- 1/4 primary: 310 turns on two layers x 0.45mm AWG26 (half A2 to A2)
(not sure about that one)

Soldano SLO100 OT
is similar to C3070, except is 32x50mm and has an higher primary impedance.


Some uningegneristic impressions that need to be confirmed:
- M6 works like 6L6GC, stays cleaner up to a point where it starts to add more harmonics (like more NFB)
- M27 works like EL34, more vintage oriented, cruncier, better on saturation (like less NFB)
- M19 and M26 works like EL84, smoother and adds a bit more of a bassy (nice for EL84 too)

Then some very useful links:
http://www.jensen-transformers.com/an/Audio Transformers Chapter.pdf
http://www.gyraf.dk/schematics/RadioDesigners Handbook - Ch.5 - Transformers.pdf
Index of ../Transfos/Papers/

Some useful links:
http://ecee.colorado.edu/copec/book/slides/Ch12slide.pdf
http://www.geofex.com/article_folders/xformer_des/xformer.htm
http://www.jfe-steel.co.jp/en/products/electrical/catalog/f1e-001.pdf
EDCOR - M-6 Steel Lamination
http://www.calvin.edu/~pribeiro/IEEE/ieee_cd/chapters/pdffiles/c4pdf.pdf

Some useful links that need translation:
Transformator wyj?ciowy
http://www.cfd.tu-berlin.de/~panek/cykin/cykin1.zip
http://www.cfd.tu-berlin.de/~panek/cykin/cykin2.zip
http://www.cfd.tu-berlin.de/~panek/cykin/cykin3.zip

Does anyone has some more info on Guitar Amps' OTs and on iron effect on sound?

Thank you all!
 
An internal link to a BudP post:

BudP said:
The difference in sonic’s is interesting. An amorphous core OPT for PP will be very clear, have great transient response and excellent tonality. However, they are somewhat one dimensional in that most of the fine gradient detail that provides internal note structure and makes transient noises into musical events, has been stripped away by the lack of E Field coupling and the higher dielectric constant materials used in the coils, essentially half of the information must be lost to avoid frequency response peaks.

An M3 commercial core, properly constructed for audio purposes, will sound slightly softer than an Amorphous core transformer. There is after all more distortion, and when comparing 99.997% correct signals (Amorphous) with 99.993% correct signals (M3), this is what you should expect. However, there can be a great deal more internal information made available, for all musical signals, because you do not have to throw away half of the signal and the antenna event is actually encouraged during it's E Field portion.

In addition the M3 and M6 core are basically only providing a ferrous bounding box for the coil antenna event above 400 Hz. The material still responds but the losses are so high, with extended frequencies, that it neither adds nor subtracts to the signal passing from coil to coil, so long as that core construction issue has been dealt with. Neither amorphous core not M3 core is "better", they have differing strengths, and when both are used properly either will provide superb audio, within the limitations found above, and their pricing will be about the same too. An M6 core unit, with more distortion and only slightly less information, without quite the refinement of either of the other materials, is a much less expensive alternative, with very few drawbacks.

http://www.diyaudio.com/forums/tube...er-silicon-steel-amorphous-3.html#post1915988
 
BudP said:
they are somewhat one dimensional in that most of the fine gradient detail that provides internal note structure and makes transient noises into musical events, has been stripped away by the lack of E Field coupling and the higher dielectric constant materials used in the coils, essentially half of the information must be lost to avoid frequency response peaks.
With all possible respect, the terms I've highlighted in aqua are all meaningless. Much of this quote reads like utter nonsense. Some of it most definitely is utter nonsense.

On diyAudio, the "woo-woo" black magic stuff usually stays on the audiophile sub-forums, and we try to stick to engineering and physical reality in the instruments and amps sub-forum. I note that the Bud P. quote above comes from one of the "woo-woo" forums, and includes discussion of black-magic single-ended 300B triode amps and other very expensive, very bad engineering.

I would not take anything from this quote seriously. Enjoy it as a joke, maybe. It's pretty funny! :)

Incidentally, there are lots more similar jokes to be found in this other diyAudio thread: Funniest snake oil theories

-Gnobuddy
 
zintolo
we appreciate the values you have shared,is it possible for you to draw or sketch the connections like in this attachment
 

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Diameter of all wires is shown with varnish.

The approximate dimensions of the core are 2668/1998 for Marshall 100W:
Set - 37 mm
Width of the tongue is 41 mm
Width of sides is 20 mm
Window height is 60 mm
Width of the window is 18 mm
Thickness of the plates is 0.35 - 0.5 mm, depending on the year of production.
 
jazbo8, there are two ways of reading the messages.
One is reading the messages, the other one is reading between the lines.

I perfectly know what engel wants, but due to the book he cited, I also know that Engl already has all the other informations of the formula, except the voltage.

That's what I gave him, then it's just a matter of calculating it.
 

PRR

Member
Joined 2003
Paid Member
..teach us how dagnall c1998 came up with 620+620 primary.............

np=E x 10^8 / 4.44 x Ac x F x B

np=no. of turns
Ac=area of the core in sq.in
4.44=constant
F=lowest frequency
B=flux density lines/sq.in or gauss x 6.45 lines/s.in

Assemble known data. (Why do you expect US to do this??)

Many cores listed above are near 38mm square stack. This is 2.24 square inches.

Lowest note of guitar is nominally 82Hz. Whether we need full power at 82Hz is a musical question, not engineering.

If you have 490V supply you have say 440V peak or 880V p-p one side, which is 314V RMS one side. 630V RMS both sides.

I am NOT a transformer designer so some of this is WRONG.

As an extreme guess, iron can take 10,000 Gauss which seems to be 64,000 lines.

Bottom of fraction is 4.44 * 2.24 * 82 * 64,000 is 52,194,509

Top of fraction is 630 * 10^8 which is 63,000,000,000.

63,000,000,000 / 52,194,509 gives 1,207 turns. 1,207 is "exactly" 620+620=1,240 within the coarseness of our assumptions (82Hz, 440Vpk, 10K Gauss).
 
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