Another famous passive EQ

[NewYorkDave]

I thought I'd do one more before I turn off the scanner for the night.

Here's a 1950 article by Cinema Engineering president, Art Davis, that includes info on the classic 4031-B equalizer made by his company.

1.5Meg PDF

 

[Mark Burnley]

Ooh ooh..

..is this the groovy looking one in Cyclopedia?

I think they've got a few at Toe Rag studios in London.

Downloading now...thanks for the scans!

:thumb:

(BTW, check your mail Dave!)

Mark

 

[NewYorkDave]

[quote author="Mark Burnley"]
..is this the groovy looking one in Cyclopedia?[/quote]

The very same.

I think they've got a few at Toe Rag studios in London.

That's what I've heard.

(BTW, check your mail Dave!)

"Package" received in good condition. Thanks! I've already shared it with the group. :green:

 

[bradzatitagain]

You're really giving today Dave, go man, go! Der skeemos out der in www land somesplace? Thanks for that cool mixer dope too.

 

[gyraf]

:shock: Thanks..!!!!!

Jakob E.

 

[NewYorkDave]

I haven't found any schematics of the 4031-B, but the Langevin EQ251-A (which was reverse-engineered by my friend Rick, and can be found on Gyraf's site) is nearly the same circuit according to most reports. It's been claimed that Art Davis was involved in the design of the Langevin EQ as well.

Shameless plug: the NYD EQ can give you the same curves with much less circuit complexity, albeit with nonconstant input/output impedances.

 

[gyraf]

Did anyone ever find reliable schematics for the Cinema engineering 4031-B EQ?

Jakob E.

 

[emrr]

I re-engineered a pair of Hycor variant from 2dB steps to 1dB steps for a mastering house, comparing to the 251 was adequate. 

 

[gyraf]

So you would say that the 4031-B is more or less a Langevin 251?

Jakob E.

 

[emrr]

Yes, outside of small tweaks.  All evidence still suggests Art Davis or his team designed them all.  Cinema, Langevin, Hycor, Altec. 

 

[ruffrecords]

Anyone have a copy of the pdf? The link is broken.

Cheers

Ian

 

[mjrippe]

Anyone have a copy of the pdf? The link is broken.

Cheers

Ian

Just added to the Technical Documents section. GroupDIY Audio Forum New link below.

 

[opacheco]

I have searched the "1950 article by Cinema Engineering president, Art Davis, that includes info on the classic 4031-B equalizer made by his company" in everywhere and I found nothing at all!...Could someone show me the direct link to please?

Thanks anticipeted!
opacheco

 

[mjrippe]

https://groupdiy.com/threads/cinema-engineering.63274/

 

[egroys]

Old Thread Resurection!

I just acquired one of these bad boys!

The low freq pot is in a funky state: it turns down beautifully, but turning it up is clunky and chunky and really feels like I am forcing it.
Is there any way to remedy this or am I SOL?

 

[JohnRoberts]

Replace the bad pot....

JR

 

[pucho812]

Old Thread Resurection!

I just acquired one of these bad boys!

The low freq pot is in a funky state: it turns down beautifully, but turning it up is clunky and chunky and really feels like I am forcing it.
Is there any way to remedy this or am I SOL?

Can you take it apart and clean it?

 

[egroys]

So these pots are HONKERS and I don't know how I found replace them.
But the protective lids do come right off and I see the issue...now I just need to find a way to straighten out these suckers.

Edit: bent and back in business!

 

[egroys]

Testing, everything EXCEPT the 3k band looks correct--it boosts 10k and above whereas the 5 and 10k look correct (testing on pink noise).
I see the brochure but wonder if anyone has found a schematic?