Neve Lo1066 clone vs. Carnhill VTB 2569

[KraftWerk]

Greetings to all,
I made LO 1066, following CJ's instructions.
The only difference is a slightly thinner wire, which is 0.27 mm in cross-section, and a slightly thicker polly gap, which is now 0.05 mm (instead of 0.00135 inch).
My Varnish is thinner and I was not able to get such a thick layer even though I dipped it several times..
I put the transformer in Vakum owen...
I dried it in the oven.
I'm not satisfied.
I compared the transformer with exactly the same conditions by putting it in the AML ez 73 and made some measurements.
At first listen, without measuring, everything seemed fine...but, by listening carefully, I confirmed 2 things;
1. My transformer is a little quiet (it's not a problem)...without measuring I thought it was maybe around 0.5 db...later I saw on measurements that it was around 0.3 db
2. The difference is in the treble...it's not too big, but you can hear it if you listen carefully.
3. My transformer is not in class with Carnhill VTB. He is more like 2d, while for Carnhill I can say that he is 2d. The difference is not heaven and earth,, but I feel them and can easily distinguish them by blind listening.

I would like to upgrade my transformer.
The measurements clearly show a huge difference in the frequency response at high tones.
I know it's not in the audible spectrum, but maybe that's why the Carnhill sounds HiFi, rounded and clean compared to mine, which is a bit lifeless and boring.
Can someone from you help me with this?

-Tomorrow I will upgrade my winding..I read some articles about winding and I noticed differences that I will correct.
I will also buy a new varnish..
What do you think I still have to do...?

 

[CJ]

What kind of laminations did you use?

Sometimes the inductance will go up over time as the steel gets broken in. You can hit it hard with 60 cycles to speed up this process. Doc Hoyer use to do this when building stereo inductors, he would break them in with 60 cps then adjust the gaps to get them to match.

If you used smaller wire then the turns will be closer together which will increase capacitance and therefore cut the high end.

You could measure the capacitance with a meter.

Did you scatter wind or lay down even layers?

The original Neve outputs were wound so tight , real close to the breaking point of the wire, that when I was unwinding them some of the turns would snap. This was done to get the leakage inductance down and also to get all the turns on there.

Also, try winding a new one and test the high end before and after varnish.

 

[Dylan W]

Your graphs show a pretty significant difference in the high end. 1 db down at 20k and 4 db down at 50k in the clone. Even if those level differences are out of audible range, the resulting phase shift will be audible in the high-mids and highs. That could well account for a lack of “3d-ness” in your copy.

 

[CJ]

Did you reverse wind primary #1?

 

[KraftWerk]

What kind of laminations did you use?

Sometimes the inductance will go up over time as the steel gets broken in. You can hit it hard with 60 cycles to speed up this process. Doc Hoyer use to do this when building stereo inductors, he would break them in with 60 cps then adjust the gaps to get them to match.

If you used smaller wire then the turns will be closer together which will increase capacitance and therefore cut the high end.

You could measure the capacitance with a meter.

Did you scatter wind or lay down even layers?

The original Neve outputs were wound so tight , real close to the breaking point of the wire, that when I was unwinding them some of the turns would snap. This was done to get the leakage inductance down and also to get all the turns on there.

Also, try winding a new one and test the high end before and after varnish.

Thanks for reply guys...
EI57 G6 H4 grain oriented steel...54 lam , from China...Funny ,cannot find to buy laminations in Europe,noone want to sell 3,5 or 10 kg laminations and 20,50 bobbins...not even reply to my emails.
Woman from China company sent me 3kg and 12 bobbins for FREE. Just payed Fedex 40 dollars.
Tomorrow i will meaasure capacitance and post it.
Even Layers, near the end, it was not so perfect...but still nice..
I wound preatty hard, I have tensioner...tomorrow i will try with even more tension.
I think tomorrow will have time to make new ...and compare all 3.

I have little thicker wire..0.30 mm, but im affraid it will not fit in bobbin..with 0.27 is already full bobbin.
Cj, i dont understand what you saying about 60 cps...can you please explain what to do?
Now sleeping..tomorrow i will continue..I really enjoy in this..

 

[CJ]

Just hammer the primary with a variac till it gets hot, inductance will go up.
Take a before and after reading.

The original does not track like the modern day Carnhill, so if your wondering why yours looks different then that would be on reason, u less you have a really old Carnhill.

 

[KraftWerk]

I order one variac, tomorrow will be here, so we will try.
Also,I would like to make one with closer spec to modern Carnhills.I saw somewhere on web schematics..
What I see through bobbin, Carnhill uses thinner wire on very slim bobbin, I was looking to buy bobbin same this because fitting in 500 series, but cannot find.

 

[KraftWerk]

Work in progress...

 

[andia]

Did you reverse wind primary #1?

what does reverse wind mean? is it just reverse start and end after winding or is it reversed winding direction or both?

 

[KraftWerk]

I asked my self same question...but, according to CJ schematics, I start winding from Right to Left and opposite wind direction...maybe I'm wrong...

 

[CJ]

reverse winding involves reversing the direction of your winding spindle and does not have anything to do with left or right starts/finishes, unless you do just one layer,

the slimmer bobbin i believe is for the 1U rack mount version of the xfmr, being less desirable for bass, the Sowter having a bigger core for more bass,

you can make a slimmed down bobbin by simply cutting a sq bobbin in half and sanding down the sides and taping it together on the mandrel.

likewise you can fashion an over square bobbin by using two bobbins and cutting them into 1/4 - 3/4 halfs and taping the larger halves together, adjusting for required dimensions,

 

[KraftWerk]

N

reverse winding involves reversing the direction of your winding spindle and does not have anything to do with left or right starts/finishes, unless you do just one layer,

Now is all clear ,thanks CJ..

 

[KraftWerk]

the slimmer bobbin i believe is for the 1U rack mount version of the xfmr, being less desirable for bass, the Sowter having a bigger core for more bass,

you can make a slimmed down bobbin by simply cutting a sq bobbin in half and sanding down the sides and taping it together on the mandrel.

likewise you can fashion an over square bobbin by using two bobbins and cutting them into 1/4 - 3/4 halfs and taping the larger halves together, adjusting for required dimensions,

Really good to know...

 

[KraftWerk]

I made another one..I made some changes in winding according to CJs explanation,made changes in isulation,made changes on booth sides ,primar and secundar, and what i see on graph, i see big improvements..
This is without gap...booth mine OPT dont have gap...I will now make gap and compare results.
I am old school, listening more relevant than mesurement ...

 

[CJ]

a gap will bring the primary inductance way down, so if you can, use a low z source to check the bottom end,

did you do the reverse wind?

 

[KraftWerk]

Yes ,I did..same you told me..I only changed wind direction,sound is absolutely great now...high frequencies is Sooo nice and smooth... tomorrow I will make more listening tests. I have one question ..I would like to make transformer 1 db louder, to be in range with Carnhill can I only increase turns on secundar,or? Tomorrow I will make another one...and try few more things...

 

[CJ]

Yes , more sec turns,

To make room you can squeeze the coil real tight after every section. That big of wire tends to form an arc while you wind which makes it bulge out in the middle and hits the lam.

In other words you want to keep the turns as square as possible.

A painful way to do this is to hand wind and bend the wire over the corners of the bobbin two of three times to take the stiffness out and get a better bend around the corner.

Our winders use to use a huge wooden mallet and hammer on the big coils with everything they had in order to get the turns to lay flat. They did this over the insulation, 30 PB, so the #14 heavy build would be ok.

I'm like "dude your gonna get some shorted turns if you beat on it like a one legged step child" and there like "I don't give a crap, I get paid by the hour, go back to your machine and chop some more lams"
WTF, jus sayin...

 

[KraftWerk]

To make room you can squeeze the coil real tight after every section. That big of wire tends to form an arc while you wind which makes it bulge out in the middle and hits the lam.

Ok,I will add more tension and find peace of wood..for beating ..i still have little space, but today i plan to make Ver.4 with 2 size of wires 28 G,29 G...so I will need more space. I will also try to increase few turns on secundar to make Ver .4 louder 0.5 db.
Ver.3 is now finnish and I will try to measure differences before and after Varnishing, but, Im not satisfy with varnish I have, he adds no colour, layer is really thin, and even I dip bobbin ( vacuum ) I not see that bobin is sealed. Before Varnishing I will connect him on Variac, and measure all, resistance,Capacitance,Inductivity..after Varnish, measurement too...do you have any other idea what to do?

Here is new mesurement
Gap vs no gap
300 vs 1200
Carnhill vs. Ver.3

Ahh...I would also like to make API transformers..I have Litz wire 4x 0.30..after this project.
Also, something on clean side, same Sowter....
Is there any OPT with more complex winding, some esoteric stuf? Not mather the time for production?
Im on vacation 1 month and here is very cold...

 

[KraftWerk]

I was working all day on this, 2more version finnished..
I added 20 more turns on secundar, now have similar output..little tricky to wound because wire not finnish near end of layer..so, all opt is now little bigger,but still fit...
Cj..i think now my transformer sound great, but,,,what I must to to extend high frequencies simillar Carnhill? on blind test dont have important differences ( i have genelec 1030a monitors,work with them over 20 years ) I have some books, I think tomorrow not make transformers,tomorrow reading...

 

[KraftWerk]

Following Cj's instructions and his scheme, I managed to make a faithful copy of LO 1166 down to the smallest detail. Wire thickness, arrangement of coils, insulation, gap... In the picture it is this beauty on a wooden stand. There was enough space to fit all the wire...but not even one layer would fit. The hammer worked over the wood. In my AML EZ 73 it sounds rich and creamy, but darker than the Carnhil WTB 2569. I am very satisfied. At first I was worried and tried to find a way to make the transformer a little more open, but I realized that it was wrong. The original specifications are important here. I also made another transformer that is almost identical in sound to the Carnhill wtb.
My wife took care of the styling of the cable , so I can say that this creation is a limited edition... I still haven't put it in the vacuum oven, I'll do that in a few days.
I will give myself some effort and try to measure the inductance and capacity..does anyone know a simple and efficient way to do it?