Mo Metal

[Learner]

[quote author="soundguy"]

how do henries in these examples relate to the sound that is coming out of the transformer?

dave[/quote]

The inductance will influence the reactance X L which is 2 x pi x F x L.

By substituting various value in F(frequency) eg. sweep oscillator, you can see that the reactance will vary due the frequency causing higher reactance at higher frequency.

if current is increasing in magnitude, the induced voltage will "push against" the electron flow; if current is decreasing, the polarity will reverse and "push with" the electron flow to oppose the decrease. This opposition to current change is called reactance, rather than resistance.

Impedance is a comprehensive expression of any and all forms of opposition to electron flow, including both resistance and reactance. It is present in all circuits, and in all components. When alternating current goes through an impedance, a voltage drop is produced that is somewhere between 0o and 90o out of phase with the current. Impedance is mathematically symbolized by the letter "Z" and is measured in the unit of ohms (Ω), in complex form.

Perfect resistors possess resistance, but not reactance. Perfect inductors and perfect capacitors possess reactance but no resistance. All components possess impedance, and because of this universal quality, it makes sense to translate all component values (resistance, inductance, capacitance) into common terms of impedance as the first step in analyzing an AC circuit.

Go here for more
AC turorial

 

[CJ]

Raf, if you increase the amount of core, you get more cross secxtion which means more inductance.
And yes, the sweep curve will change with the dc. I am looking for trends between the 5 transformers, so I don't care about actual operating conditions so much. I might add that I tested som Marinair mic and line inputs, the old black vintage, and they were as flat as a pancake with very little phase shift in the audio band, but this would probably change in an in circuit test. So if the inputs are pretty flat, this would mean most of the Neve transformer sound is from the output, although I am just guessing.

Thes ouputs ar flat all the way down to 1 hertz.

 

[CJ]

Wow. The Carnhill re-issue has a huge spike at 400 kc. Jumps from 4 to 14 volts!
Then it dies out.
Sweeping the Sowter now. Looks like it has the two peaks just like the Marinairs. Different voltage output, 5 in gives 3.8 out instead of 4.3 like the others.
Dang batts went dead in my camera, gotta see if I can find some new ones.

 

[CJ]

Ok, got some batteries for the digi-cam. Here are the 1000 hz ringing tests.
This is with no Zobel network on the secondary:

I might have to hit them with thet variac to get some better curves tomorrow.

 

[CJ]

Here are some frequency curves-no network on the secondary.
If you look at the ringing trace of the Carnhill, you can see what the big spike does to it.

Marinair LO 1166A and Carnhill Re-issue:

I have only seen one other transformer with three peaks, a black UTC HA-100X:

Marinair LO2567:

 

[peter purpose]

I love your transformer stuff Chris... you are a true XFMR DGMM :thumb:

 

[CJ]

Thanks Peter. I love your avatar!
(what the hell is a DGMM you guys? Is it good or bad?)

 

[peter purpose]

DGMM ... DEMI GOD & MACHO MAN.. :guinness:

 

[gyraf]

Very nice info!

Will we know the air-gap sizes? The lamination types used? Winding geometry?

This may be a job for my local inductor-winder..

:grin:

Jakob E.

 

[mik]

CJ ........ Maestro!


:sam: :sam: :sam: :green:

 

[CJ]

OK, the results are in for a 20 hz saturation test.
I layed all the scope shots out to compare.

The setup is a 5 ohm resistor in series with the primary to which the channel a scope leads are attached. The bottom waves are taken with the scope across the secondary of the transformer.
A 20 hz sine wave was used.
A 1 k resistor was put across the secondary as a load, but made little difference.

EDIT: I linked the pics to speewd up loading.

http://vacuumbrain.com/The_Lab/TA/Marinair/layout.jpg

Here is a shot of magnetizing current on top and the unaffected sine wave on the bottom:

http://vacuumbrain.com/The_Lab/TA/Marinair/sowter_30.jpg

Here are the comparisons of the transformers at 45 volts input.
The top mag wave indicates saturation, as the amplitude of the level spot is 1/2 the amplitude of the peak.
You can see the effect that the magnetizing current is having on the output .
The Sowter did not distort it's output as much as the LO 1166A and Carnhill reissue.
The Marinair and Carnhill look fairly similar:



http://vacuumbrain.com/The_Lab/TA/Marinair/1166_45.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/carnhill_45.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/sowter_45.jpg


Here iare the same three at 50 volts. The Marinair and Carnhill are having a real bad time.
The Sowter is starting to feel a little ill also, but not as much:

http://vacuumbrain.com/The_Lab/TA/Marinair/1166_50.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/carnhill_50.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/sowter_50.jpg

OK, gotta run. B-H shots tomorrow.
cj

 

[Ian MacGregor]

Wow... sweet stuff. Seems to confirm our (the studio I work at) conclusion that the Sowter is cleaner than the Neve originals.

Ian

Thanks again CJ.

 

[CJ]

The Sowter has a cleaner bass response and behaves pretty much like the Marinairs at the top end.
The bass response difference is because of the 25 percent more lams.

The Carnhill behaves pretty much like the the Marinair at the bottom end, but has that huge self res spike which means it will differ at the top end compared to the Marinair and Sowter.

I suspect that Carnhill cheated a bit and wound the transformer as pri-sec instead of pri-sec-sec-pri as is probably the structure of the Marinair and Sowter.

Funny, all you solder pushers know more about Neve outputs than the big wigs over at Fletchers place.

Even Geoff had it backwards. If you read that post linked to at the Neve meta, he mentions that the Carnhill had problems at the low end, not the top end, which is bass ackwards. And this guy knows every nut, bolt, cap. transistor that ever went in to a Neve console.

:guinness:

 

[Kev]

[quote author="CJ"] ... Funny, all you solder pushers know more about Neve outputs than the big wigs over at Fletchers place.[/quote]

John K and Geoff do know there stuff but everyone can make a mistake.
It happens as you get older.
:sad:
I'm sure John K would love to able to play with stuff at the level that some of you guys do BUT time is money and he has a business to run.

keep it up cj
people are watching
:thumb:

 

[CJ]

Kev, are you trying to make me more paranoid? :razz:

OK, I ran some B-H curves.
The 3 gapped transformers look a lot different than the ungapped
LO2567.
Here is a comparison of the ungapped 2567 with the gapped 1166A:

http://vacuumbrain.com/The_Lab/TA/Marinair/2567_bh_10sine.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/1166_bh_10sine.jpg

The Marinair and Carnhill look very similar as expected, as their magnetizing current traces were very close.
The biggest difference I could see was at 10 hertz:

http://vacuumbrain.com/The_Lab/TA/Marinair/carnhill_bh_10sq.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/1166_bh_10sq.jpg

The Sowter had a much more rounded curve at the same saturation input voltage than the Carnhill/Marinair x-formers.
Probably due to the extra iron:

http://vacuumbrain.com/The_Lab/TA/Marinair/carnhill_bh_40sine.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/sowter_bh_40sine.jpg

More obvious with a 20 hertz square wave:

http://vacuumbrain.com/The_Lab/TA/Marinair/carnhill_bh_20sq.jpg

http://vacuumbrain.com/The_Lab/TA/Marinair/sowter_bh_20sq.jpg

OK, thats about it. Just some leakage tests tomorrow and I am ready to take apart the Marinair LO2567 to see whats going on.

see ya,
cj :guinness:

 

[Kev]

excellent stuff cj
keep it up

the curves do tell a very interesting story

 

[gyraf]

What can I say.. :shock: ..Thanks..!

Jakob E.

 

[rafafredd]

CJ, the work you are doing is very valuable, but I would choose one of the originals LO1166 gapped transformers if I would take one apart. Don´t take me wrong. What you are doing is great. It´s just that the LO1166 is the original transformer on the 1272/1073 and many others designs that use the famous NEVE class A output stage.

But, if it´s not an option for you, off coarse we would still love to see your dissection of the ungapped LO2567 one!

Keep up the good work :thumb:

 

[CJ]

Joel would have a Texas Bar B Que with me on the grill if I touched the 1166A.
However, I have been told that the winding structure of the 2567 and 1166 is the same. Same core, same coil, just a gap, that's all.

I am negotiating on the Carnhill so maybe I will have two to take apart.

It's not a very glamorous transformer, crude M6 with big wire and a fairly simple winding structure. Not like a Peerless S-217-D or anything.


:guinness:

 

[Dan Kennedy]

There is a lot of mythology in these things. I use a slightly modified version of the 8751 in the NV series preamps. It's distortion characteristics are closer to the original, largely because I asked Brian to remove some of the lams so it would fit in a single rack space, which the 51 won't.

To quote Fletcher: It ain't rocket surgery.

But it is an art.

The most critical thing that I've seen about this style of transformer is the accuracy of assembly to maintain the low frequency performance, which is critically affected by the gap spacing.

Otherwise it's mostly a glorified power transformer.