PEV-style "passive" EQ experiments

etheory said:

Another possible few output transformers could be the:
Lundahl LL1660 - 1+1+1+1 : 2.5+2.5 or LL1671 - 1+1+1+1 : 2+2

Click to expand...

No, the inductance and DCr are not adapted.
The 7904 or 7902 seem to be the most adequate. The DCr of the secondaries of the 7904 is a little on the high side, resulting in an effective output impedance of about 150r if you choose to run it at 1:2. I don't have the specs of the original PEV, but it may well be about the same.

Simulation shows that the intermediate stage should be capable of about 5Vrms, suggesting a gain of 2 for the output section would provide adequate headroom (ca. +22dBu open voltage, +20 into 600r)

I'm a bit confused.

The 7904 is not applicable as it is 1+1:1+1 and hence missing 2 primary coils.

HOWEVER the 7902 is looking more in the ballpark for sure.

But it has a confusing spec (for me anyway) of effectively two isolated 1+1:1+1 parts, which make up the 1+1+1+1:1+1+1+1 whole. But I'm not sure if the PEV output stage would work if the upper and lower half were running through completely separated transformer sections?

From the spec sheet:

"The transformer consists of two coils each with two primary and two secondary windings separated by
electrostatic shields"

If my language is confusing this might help:
http://www.lundahl.se/pdf/7901_02.pdf

etheory said:

I'm a bit confused.

The 7904 is not applicable as it is 1+1:1+1 and hence missing 2 primary coils.

Click to expand...

Sorry, typo, I meant 7903.

But it has a confusing spec (for me anyway) of effectively two isolated 1+1:1+1 parts, which make up the 1+1+1+1:1+1+1+1 whole. But I'm not sure if the PEV output stage would work if the upper and lower half were running through completely separated transformer sections?

From the spec sheet:

"The transformer consists of two coils each with two primary and two secondary windings separated by
electrostatic shields"

If my language is confusing this might help:

Click to expand...

THEIR language is confusing. When they write coil they mean bobbin. So definitelly all windings are on the same magnetic core, but on two opposite jambs. And in fact the circuit would work with two independant transformers, with a slight decrease in performance though.Then I must admit it is somewhat difficult to make an educated choice. It seems all three models 7901, 02 & 03) would be adequate, requiring different types of arrangement definitely parallel for 01, series for 02, and hybrid for 03). I would tend to think that the 02, being 1:1:1:1:1... has the best coupling factor, but it's just guesswork.
You should probably write them; they are known to be quite responsive.

Digging up a grave on this one.
Heard one of these EQs a while ago and sparked my interest to clone.
Have any of you guys sorted out the transformers over there years?