Neve LO1166 gapped transformers

[Spencerleehorton]

Had some EI75 lams sitting around so I thought I’d build some LO1166 gapped output transformers.
Specs wise they come out as per original winding sheet with a little more inductance which is nice.
Pri A - 9.2R (80mh) Pri B - 8R (80mh)
Sec A - 21R (220mh) Sec B - 21.2R (220mh)

Will test them in a Neve 1290 and a 2254.

Have built 5 pairs so far.

 

[CJ]

Holy shit!

 

[Spencerleehorton]

Not varnished yet and still need to trim the bolts as they are a tad long.
Used an I and slotted the turret board, took your advise as well CJ with clamping the I to the E then securing all the bolts, made my own bobbins which turned out well.
Very happy with them so far and they fit inside a 1U as they are only 38mm wide.

 

[peterc]

Very nice.

 

[Whoops]

Very nice, congrats

What did you use for the gap? and how thick?

 

[Spencerleehorton]

I used a bit of masking tape which measured the same as what was on the winding sheet. I did find a mistake on the winding sheet which I rectified.

 

[Whoops]

I did find a mistake on the winding sheet which I rectified.

Thanks

Was the winding sheet from CJ?

Could you please share what was the mistake?

 

[Spencerleehorton]

It’s in the tech docs section under Neve
Sec B should be 0.010” (0.25mm) gauge rather than 0.013”(0.314mm).
Winding what it says on there ends up being only 14ohm on the sec B and needs to be 21 ohms same as sec A.

Masking tape measures about 0.7mm

 

[Moby]

Looks nice! Do you know the manufacturer of the laminations? Are you happy with the inductance value? Can you measure it?

 

[Deadly Mix]

I'm having trouble getting my hands on a pair of Marinair 1166. I've bought and used Neve knockoffs with Carnhill and even paid for mods that include Carnhill "upgrades" for the transformers.
My experience taught me that I hate Carnhill transformers. Not even just "not as good as the real thing". I found stuff with Carnhill transformers to simply sound unusable.
To my ears, gear with Carnhill transformers sounds harsh like any other cheap audio tool.

I read another post of yours about your transformers from 2017. I was wondering if they've been compared against Marinair yet and whether they're available for sale.

 

[Spencerleehorton]

Everyone seemed to like my previous transformers and I haven’t really had time to do many of these other ones.
I have these and the other ones from 2017 in some of my Neves and I can’t tell the difference!
These new ones hit the same spec but are thinner so can be used in a 1U.
I have about enough lams to do about 10 more and I want to keep a few for myself.
I’ll update when I’ve wound them all and see what I’ve got left over if your still interested.

 

[Walter66]

 

[Deadly Mix]

Everyone seemed to like my previous transformers and I haven’t really had time to do many of these other ones.
I have these and the other ones from 2017 in some of my Neves and I can’t tell the difference!
These new ones hit the same spec but are thinner so can be used in a 1U.
I have about enough lams to do about 10 more and I want to keep a few for myself.
I’ll update when I’ve wound them all and see what I’ve got left over if your still interested.

I'm interested, but I just learned from a link Mike at Hairball sent me that there are actually 4 versions of the 1166. An old comment that I think came from CJ (sorry if I'm mistaken, I just remember the avatar on that thread) said that the 2254's 1166 had a secondary impedance of 200ohms (just like the primary) and the 1073's was 600.
The transformer spec sheet Mike sent me verifies that these 2 versions do. In fact, exist.


So, I suppose the question I'm getting at is: Do you have one that matches the 2254 specs?
I can screen shot the information I'm referring to if that helps. I just have to come back because I came here through my email and need to open my email to get to it lol.

 

[Deadly Mix]

https://www.technicalaudio.com/reading/neve_xfmrs/neve_edo7113.html

 

[Whoops]

said that the 2254's 1166 had a secondary impedance of 200ohms (just like the primary) and the 1073's was 600.
The transformer spec sheet Mike sent me verifies that these 2 versions do. In fact, exist.

it's not 2 different versions, the LO1166 secondary can be strapped for 150 or for 600, it depends if you connect the secondary in Series or in Parallel. It's just that

 

[Spencerleehorton]

Yeah as whoops said and yes I have built a stereo 2254 using mine on output.

 

[CJ]

You need to let the lams rust to get the Never sound.

I can not find where it says .033 on the winding sheet.

Note that the wire size, 0.010 and 0.013 is wire diameter.

Back then I was mmustaken in believing g that wire diameter could be used to find the gauge on a copper wire table but that is not the case. Usually magnet wire charts use diameter to specify the bare wire size without insulation.

So a .013 piece of bare copper could end up with perhaps three different actual diameters depending on the insulation thickness.

And also insulation technology gas changed over the years so you can get higher kV ratings for the same thickness of insulation, so new wire might be more copper and less insulation.

Then there us the copper purity question, yesterday's wire might have less resistance per 1000 ft than today's wire. So you have to experiment to get the turns and dcr to match up.

And those Neves were wound tighter than anything I have ever seen, the wire was breaking as I unwound it due to the stress. The must gave used a machine machine motor geared down 10 to 1 to get the wire that tight, in other words, don't buy an old Neve output and expect it to last. Leakage inductance sure is good but those poor winders must gave carpal tunnel by now.

 

[Deadly Mix]

I was watching somebody make chainlink fence the other day and he's using this hand-crank to wind wire around this tool that looks like a tuning fork at the end of the crank.
My first thought was "Why doesn't he connect a motor to the crank and save himself the work?" My second thought was "I wonder if he made a small version of this to assist someone with making transformers by hand, if the ability to make it that much tighter would lead to a better transformer than winding with fingers alone (which is the only way I've seen it done).
So maybe they DID use a special tool like the chainlink tool I saw. Perhaps that's part of Mr Neve's secret recipe to the Marinair TFs

 

[Deadly Mix]

And also insulation technology gas changed over the years so you can get higher kV ratings for the same thickness of insulation, so new wire might be more copper and less insulation.

Then there us the copper purity question, yesterday's wire might have less resistance per 1000 ft than today's wire. So you have to experiment to get the turns and dcr to match up.

Not that any of that was difficult to follow, wire is smaller with shielding removed when measurement includes shield-- simple stuff, but the overall flood of information I've been picking up over the process of just wanting to perform a simple part replacement is making me question whether I'm in over my head.

I thought it would be as simple as: Snip leads on the Carnhill and remove it > Install Marinair and Solder the wires exactly as they were on the Carnhill > Repeat for the second unit > Pop into a lunchbox > Master the next project on my schedule.
I'm getting the impression that's it's not gonna be so easy.

 

[CJ]

Its easy. You have the power!