Neve Transformers

[ruffrecords]

CJ has kindly updated the information at the beginning of this thread so we can now see the differences between the 10468 mic transformer and the 31267 wired backwards. It is clear that the 31267 line input transformer has about 35% more turns on all windings and the dcr of the windings are considerably higher. Overall this means a 31267 wired backwards will have a slightly worse noise performance but the final noise performance is most likely dominated by the first transistor stage so I doubt the effect is noticeable. The higher number of turns may mean the frequency respose at the high end is not as goo but on balance I think it will work OK.

Cheers

Ian

 

[shabtek]

didn't JLM determine that reversed 31267 sounded best when connecting mic to only 1 coil?

the hairball lola sounds very nice and uses a current production 10468 styled xfmr

edit:
http://www.jlmaudio.com/Neve transformer info.htm
looks like he likes only 1 coil of secondary too FWIW

 

[ruffrecords]

didn't JLM determine that reversed 31267 sounded best when connecting mic to only 1 coil?

edit:
http://www.jlmaudio.com/Neve transformer info.htm

I did not see anything on that page that mentioned how the various transformers sounded. It seems it was just a test with a 500Hz square wave. Unfortunately I could find no mention of the source impedance of the test signal which is important.

Cheers

Ian

 

[shabtek]

I did not see anything on that page that mentioned how the various transformers sounded. It seems it was just a test with a 500Hz square wave. Unfortunately I could find no mention of the source impedance of the test signal which is important.

Cheers

Ian

I guess I've always inferred that his criteria for overshoot and distortion resulted in 'better sounding' or more 10468 sounding...but indeed there is no mention of the sound.

towards the top 50Ω and 200Ω are indicated but it is not clear which if either is used for the colored traces.

 

[ruffrecords]

I guess I've always inferred that his criteria for overshoot and distortion resulted in 'better sounding' or more 10468 sounding...but indeed there is no mention of the sound.

towards the top 50Ω and 200Ω are indicated but it is not clear which if either is used for the colored traces.

You are right, they do mention two source impedances, 50 and 200 ohms but it is not clear which one the graph relates to. The thing is, I know from my own tests that with a low source impedance you can get a pronounced peak at 40KHz or so and the response can be a dB up at 20KHz. But when fed from a 150 ohm source, these transformers are flat out to beyond 40KHz. I have seen this effect on Sowter, Jensen and Cinemag mic input transformers.

Cheers

Ian

 

[Uk03878v2]

Sorry for interrupting the thread, looking at the FAO name and address, that brings back some memories
Years ago I had that shell company (Smartaction) and yes it is me but I don't live there anymore - I used it to get the information which got posted here (I was not a sales rep - I pretended to be to get the schematic)

 

[sponzorb]

On the 1166 and 2567 where it says "clear poly 2 wraps in between layers" there's probably a typo, it's 2 wraps in between sections and not layers

Sorry for asking what might be basic questions. What is the clear poly? Is it tape or just the plastic sheet? Also why are there layers? Why not just do all turns of a section in a single winding?

 

[Di_Sousa]

Sorry for asking what might be basic questions. What is the clear poly? Is it tape or just the plastic sheet?

Clear Polyester Tape

Also why are there layers? Why not just do all turns of a section in a single winding?

I don't really know what you mean.
A layer is a complete winding from on side of the bobbin to the other, when it's complete then it's a layer, then you continue winding on top of that one from one side to the other, when it's complete that's the second layer, and so on and on.

 

[sponzorb]

Clear Polyester Tape

View attachment 135031



I don't really know what you mean.
A layer is a complete winding from on side of the bobbin to the other, when it's complete then it's a layer, then you continue winding on top of that one from one side to the other, when it's complete that's the second layer, and so on and on.

Thank you! I see what you mean. I thought the layers might be cut and physically separated by the clear poly. This makes perfect sense.

 

[Di_Sousa]

I thought the layers might be cut and physically separated by the clear poly.

The layers are not cut, they are part of the full winding section.

The layers are also not separated by Clear Poly, that's a typo in CJ's notes, there's only Clear Poly tape between the different sections.

There's also a some confusion with the gauge of wire stated in the CJ's docs, CJ measured the wire with the enamel insulation, so it gives a thicker wire size, but enamel wire gauge is actually measured with the enamel/varnish removed and only the copper section is taken into account when measuring the thickness of the wire.

What happen is that if you measure the wire properly (only copper section) and follow CJ notes thickness you will end up with a wire much thicker than the one used in the original transformer and the complete winding will not fit the Bobbin.
I discovered this the hard way.

The wire used originally should be around 0,3mm (measured with the varnish removed) and not 0,35mm

I have more detailed info on this here:

https://groupdiy.com/threads/winding-the-neve-lo1166.64135/page-2#post-1004893

 

[KraftWerk]

Sorry, that's not truth. I can confirm I'm managed to make lo1166 fully according CJ specs. Also I have another records and statements,pictures and measurements.
CJ schematics is valid.
Try harder...and better read CJ posts.He already revealed The secrets of this transformer .

 

[Di_Sousa]

Sorry, that's not truth. I can confirm I'm managed to make lo1166 fully according CJ specs. Also I have another records and statements,pictures and measurements.
CJ schematics is valid.
Try harder...and better read CJ posts.He already revealed The secrets of this transformer .

I have no idea who in particular are you addressing to.

CJ winding notes are correct in terms of number of turns and winding structure,
although there's 2 relevant details for someone using the doc.

It was already confirmed by CJ that the the layers are also not separated by Clear Poly, that's it was typo in CJ's notes, and there's only Clear Poly tape between the different sections.

It was also already confirmed by CJ that the wire thickness stated in his doc was measured with the varnish/enamel on the wire, and it's not the thickness of the copper section with the enamel removed.

I also wound LO1166 and LO2567 with CJ's great docs.
Congrats for your transformer builds your work looks very good.

Best regards

 

[KraftWerk]

Sorry, I have another measurements...from 3 sources, including mine own transformer. Sec. Wire is 0.355 without enamel.

 

[Di_Sousa]

I unwinded and original Marinair LO2567 transformer and can also confirm that the wire used originaly by Marinair measures between 0,3mm and 0,32mm with the Enamel removed, so that should be close to gauge 28. I still have samples of the original wire somewhere in my workshop.
I also confirm that there's no clear ploy tape between layers and only between sections.
Regars

 

[Di_Sousa]

The one on the left was the one I unwinded, it had 2 open sections

 

[KraftWerk]

So strange .I also have wire,core and insulation from mine opened 1166.
0,35 ...I opened it alone.
Another source also have photo elaborated ( in my possession) that is 0,35...
I also wind first 50 1166 with smaller wire. Sound was lacking low end.
Not close to original.
Try to make with bigger wire. You will thanks me later.
Don't know about 2567.
CJ claimed it is basicaly same as 1166, but with small difference in turns, and ungapped.
About Polly tape, it is true, 2 turns between sections, not layers.That was typo.
I know there is several versions lo1166.
I have 2 different with identical apperiance from Marinair, but with different specs and different sound, but booth have same Secondary. Primary is different. I made booth versions
Old one VT and new one VTX...
Same depths..only higs are different.
Thanks for kind words about my copies.
They are existing only because CJ and his work.