Winding the Neve LO1166

[Whoops]

Hey guys, I tried to wind this guy based on CJ's LO-1166.pdf document but it seems that winding exceed  the space. U used the Cosmo http://www.cosmocorp.com/dwg/Cosmo_7038-0_2.pdf bobbin.

Anyone succeed with this? I also tried to simulate winding scheme and tried to change the magwire dia to smaller, but best I can do is "winding space 127%"

Mate could it be the size of your bobbin window? and also the size of the tabs?
It's a bit bigger than the original Bobbin.
The Bobbins I have have bought for US EI75 have 19.05mm x 19.05mm window, the one you are using has a window of 19.25mm x 19.25mm

I will take measurements of the bobbins I have (the measures in the pdf posted in the Edcor website are wrong) and let you know, the tabs on your bobbin seem to be a bit smaller also than the original.
I think I have the measurements of the original bobbin somewhere, will have a look.

Also whats the size of the wire you are using?

 

[CJ]

there is a 3 mil gap in the 1166,

why 3 mils?  it is a balancing act between the DC current, inductance,

but you also need to bake and dip that gapped transformer, which means you need a professional varnish tank like the one shown below.

you can also use a crock pot and some wax from a toilet gasket, (no joke) to dip the coil in wax first, then varnish the whole thing, you can also use a mix of parafin and about 30% beeswax but that stuff is expensive, maybe some parafin lamp oil might be used to thin the wax, pre-heat the coil before you dip it for max impregnation,

you can make the varnish hooks out of coat hanger,

that is a gapped Triad #108 for the 1959 Tremolux hanging around,

 

[Whoops]

I tried winding the Marinair/Neve LO2567 transformer today, it is the un-gapped version of the LO1166 with a very similar winding structure.

In CJ docs it states the wire is 0.014'', which is 0.356mm.
I used 0.35mm wire (measured with the enamel coating removed) but it's impossible to make it fit in this bobbin. I had the same exact problem as Moby described in the first post, it just doesn't fit.

here are CJ's specs for the LO2567:



I find it impossible to fit all this turns of 0,35mm wire in this bobbin,
I was winding manually but was putting constant tension on the wire, the maximum brutal tension I could, I also winded it very slowly and did even layers,
The doc states some layers with 70 turns, other with 65, as much strength I put and tension I was never able to put it more than 62 turns in a layer, that was the maximum top turns count per layer, the average was 60/61 turns.



I gave up when I had winded 923 turns, there was not a lot of space left in the bobbin and there was still 603 turns to do plus insulation tape.
This is the moment I gave up, there was not much space left:



I'm convinced there's something wrong in CJ's doc on the wire size, even if a lot of tension was used to wind the original transformers, I was also putting as much strength as humanly possible and I was far to make it fit.
Maybe CJ measure the wire size as 0.35mm (0.014'') but with the coating included, I don't know, it's a possibility, that would make the actual copper wire 0.3mm or 0,32mm in size. But I can tell that winding this transformer with 0.35mm copper wire (with the coating it measure 0,39mm) doesn't fit in this bobbin and it's a completely waste of time.

Also there seems to be something wrong in all CJ's docs on the LO2567 and the LO1166 and that is related to the Insulation.
Cj's states "2 wraps clear poly between layers" but for sure it has to mean 2 wraps between sections and not between layers, otherwise the space would be even less.
But this information is in the two different LO1166 docs and on the LO 2567 doc.
CJ seem to confirmed this in a previous post, although the docs still state the wrong info:

there is no insulation between layers, only sections IIRC, and maybe only yellow tape at that,

I will follow Spencerleehorton advice and wind this transformer with 0,3mm and thats what I advise anyone that want to wind it in the future.
will keep you guys posted

 

[Moby]

True. 0.3mm looks like realistic solution

 

[gyraf]

..could be sanity-checked by measuring and calculating actual resistance..

 

[Whoops]

..could be sanity-checked by measuring and calculating actual resistance..

I was so tired yesterday that I forgot to do that. But I will do.

thanks

 

[Whoops]

I searched the parts of the old original Marinair LO2567 transformer that I dismantled, the original wire is long gone unfortunately so I can't measure it.
But attached to the PINs board I had a tiny bit of leftover of the original wire leftover.
I was able to removed it and measure it, with the varnish coating it measured 0,33mm, so we are talking about 0,30mm wire used by Marinair (or 0,32mm maximum, but I doubt the varnish coating is only 0.01mm). I was not able to measure with the coating removed since it was so small that fell on the floor and was never seen again.

I love CJ's work and he is a reference to all of us but CJ's notes on the LO2567 transformer state the wrong wire, the original wire is definitely not 0,014inch/0,35mm but somewhere around 0,30mm.

Be aware that 0,35mm wire as stated in the notes with the coating measures between 0,39 and 0,4mm.

 

[Whoops]

i've done a fair few 1166s now and i use 0.3mm and it all gets on there, pretty tight but enough space to get the lams on.
but mines on EI-65.
i certainly dont tighten it to what CJs saying.

Hello Spencer,
do you wind it with "even layers" or do "scatter winding"?

Does anyone knows if it matters or what is the impact on the specs of an audio transformer when it's "scatter" winded instead of even layers?

thank you so much

 

[gyraf]

I can't find reference right now, but I once read an oversight article mentioning that "scatter" will get you to an average of half of worst-case parameters - meaning that it's only guaranteed to not be the worst you can do

Esoteric guitar pickup winders love the "scatter" - but probably only because this is what they can actually do

If you have the possibility of actually controlling wind geometry, you're far better off

/Jakob E.

 

[Whoops]

Hi Jakob,
I started with a very even winding, it took ages to do the first half secondary and first primary that way.
When I got to the middle of the second secondary there were already some accumulated imperfections on the "evenness" that was not possible to continue the even layers so I started to scatter wound. One benefit was that in 5 minutes the transformer was done while up do that point it took me 3 hours and a lot of hand and back pain!!!

I searched scatter winding but can't seem to find much technical info, most of the pages direct to the guitar pickups guys, but I didn't found much on audio transformers, I just found this on pickups:

"Scatter winding allows for the wire to be laid down unevenly. This puts more air space into a coil and lowers the distributed capacitance that exists between the many turns of wire.
When the capacitance is lowered, the result is that more treble will come through and the resonant peak of the pickup will increase slightly."

I can see that it might reduce slightly the capacitance, but maybe it also increases other factors. I dont know, maybe it doesnt make much difference in the end as long as the wire fits the bobbin

 

[gyraf]

and although it reduces average interwinding capacitance when compared to dumbly-tightwound, it still exhibits much more potential-capacitance than with a well thought out winding scheme