OT interleaved or not

[Regis]

This thread has been an education for me. Until now I did not know what interleaved really meant.

Thanks gentlemen!

[J M Fahey]

2 Steve Conner.
Thanks a lot for linking to the GOSS patent.
Incredible stuff and strictly to the point, including Lab measuring to confirm thet what he says is no bullsh*t.
We need more geniuses like himtoday.
What's also interesting is that although the practical application is "US made"; all the theoretical foundation comes from Japanese scientists , and we are talking the 30's, not the 70's onward.
The old accusation that "the Japanese just copied what others invented" does not seem to hold much.
Incredible.
Thanks again, we need more stuff like this.

[Diablo]

2 Steve Conner.
Thanks a lot for linking to the GOSS patent.

That's the Goss patent of Norman Goss. They also named a certain crystallographic texture the "Goss Texture".
ScienceDirect.com - Acta Metallurgica - On the development of the goss texture in iron-3% silicon

Some folks confuse Norman Goss to mean Grain Oriented Silicon Steel....it doesn't.
The confusion is because Norm Goss' work is fundamental to the development of Grain Oriented Electrical Steel, containing silicon.

[Gingertube]

A litte interesting reading from another forum - check the Bud P (he is a transformer designer and manufacturer) post #18 and his response to my post immediately below.
Anybody else here build or modify tube guitar amps? - Page 2 - diyAudio
Cheers,
Ian

[diagrammatiks]

Love bud. I'm glad he didn't retire like he thought he would years ago.

He might single handily by the best kept secret in guitar amps.

[jpfamps]

thanks to all of you for very interesting comments.

hello jpfamps
very nice to know about AC30 OT windings, however in VintagePepedalWorkshop site, they do not tell what kind of core material needs to be used, as grain oriented (M6) or not oriented (M19) will make a big difference, do somebody know
which core material for AC30 or other amps (ie 5E3 5F1) ?

I would have to say I'm always surprised just how little info there is on the web regarding valve amp output transformers, especially given the amount of DIYers.

I have no definitive information on the steel used in the JMI era AC30 transformers (which were sourced from at least 3 different manufacturers). It is also possible that the cores of any original transformers will have deteriorated over time (I understand that this is caused by carbon contamination in the steel), so even measuring the steel from an old transformer (which I can't do by the way) may not reveal the type of steel originally used. However, I'm sure that this info is out there somewhere.

What I would say is that the old JMI era AC30s have a large core when compared to other guitar amps; in fact it's the same size as the OT from a 50W Marshall, or a Twin Reverb (!); this is contrary to some information I've seen published claiming that British amps have undersized transformers. For any doubters out there I can provide photographic evidence.

The lams look like .35 mm, which would also imply a high quality unit.

I think such a large OT was employed in the AC30 as it was intended for use with bass guitar as well as guitar, and as it doesn't employ negative feedback the low frequency response is determined entirely by the transformer parameters, so a larger unit was "needed".

[benito_red]

It seems that Victoria 50212-T that is a clone of Tweed 5E8-A has an OT not interleaved. This is was they state about 50212-T:
-------------------------------------------------------
"..While many of the tonal aspects of
the amp can be attributed to the circuit design, the most key component of tonal coloration is the
output transformer that this amp is equipped with. The OT of the 50212-T is singular in the annals
of '50's Fender design. It is an enormous peice of iron...fully 50% larger than the late fifties
Bassman tranny of the same wattage. This translates into terrific bass response. It is very tight
and percussive; no low end sagginess here folks--pop that low E string and you'll get a extra
helping of that punch and definition that many describe as the "Stevie tone". Interestingly (to me
anyway), the windings are not "interleaved" in the fashion of the late '50's Bassman. This is a
straight, pedestrian layer wound transformer. This is how 90% of audio transformers were, and
still are wound. No fancy hi-fi 7 layer or 11 layer or bifilar or paranormal winding action to be found
here. What this gives you sonically is an amp that has a top end that softens up a bit when you
drive it into clipping. This is where your smooth and creamy, thick and meaty driven tones are
generated (in part). "
----------------------------------------------------------------------------
And this the link where you can find above text:

Victoria2

I strongly suspect that Fender BF OT's are not interleaved as well. And perhaps they used M19 (non grain oriented) core

[Gregg]

I'm usually very skeptical when someone claims that a "magic" tone is due to a special type of paper or an extra layer of plastic tape and even if it's so is the average amp user going to notice it during blind A/B tests and what if he likes the "wrong" OT better than the "right" one?
I also remember to have read how a Marshall tech decided to try how a Fender OT will sound and guess what - the amp still sounded like a Marshall.

[benito_red]

I'm usually very skeptical when someone claims that a "magic" tone is due to a special type of paper or an extra layer of plastic tape and even if it's so is the average amp user going to notice it during blind A/B tests and what if he likes the "wrong" OT better than the "right" one?
I also remember to have read how a Marshall tech decided to try how a Fender OT will sound and guess what - the amp still sounded like a Marshall.

I never talked of plastic vs paper former or extra plastic layer, I agree that is just oil snake.
The fact is that well known electrical laws tell that interleaving primary and secondary sections reduce the leakage inductance extending high roll off, and also the iron quality (M6 or M19) has got an important role in frequency response and eventually in distorsion.
Need not to say that freq response and distorsion can surely affect the tone

Likely those two trannies had similar characteristics in this way I'm not surprised they sounded similar

[Gregg]

I didn't mean what you said but that from the link above.

[Diablo]

I have access to all sorts of BH data for the various grades of electrical steel. Where exactly do I look on these graphs to find the "creamy distortion point"?........

[benito_red]

I have access to all sorts of BH data for the various grades of electrical steel. Where exactly do I look on these graphs to find the "creamy distortion point"?........

BH data is important to design a transformer. B stands for "magnetic induction" and it is the ratio between the "magnetic flux" and the section of the magnetic circuit, think about it as the density of magnatisation; H stands for "magnetic field" and maybe intended as the strenght that push the iron to produce a magnetic flux.

The most important properties of magnetic iron are three:
1) maximum limit of saturation (max value of B)
2) Magnetic permeability (is the ratio of B/H)
3) losses due to eddy currents
GOES perform much better then NOES from all of those above three points of view, and costs more.
If all the rest is equal,
*** higher saturation limit, means you can push harder the tranny before saturation, but remember that only the lower frequncies will eventually saturate because the flux increases when the frequency decreases.
*** higher permeability delivers more low frequencies (and perhaps a little more highs as well, but in order to extend hight end response in a significant way needs to interleave the windings)
*** (losses is not a primary issue for guitar amps)
However IIRC the NOES has got a BH curve more rounded compared to the one of the GOES and for this reason NOES should give a softer distortion when it saturates, but NOES require a bigger tranny for the same low end as it has a lower permeability.
IMO those are the main factors to keep in mind