Lang PEQ-2A clone...RESURRECTED

[damnyankee]

I agree with Abe...I'm no expert on electronics but I don't see how these filters belong the PEQ-2.  Biasrocks (Mark)'s source who gave him the hand drawn High/Low filter sections, it says 200 VDC & 400 VDC are used.  Could this be for the PEQ-1 tube model?  Plus, I don't see how the "Droop" functions work...?

Actually now that I've looked at Mark's images and the colors on the hand drawn filter section, they seem to match.  I gotta learn about inductor-based EQs.

 

[damnyankee]

Looking at Biasrocks' hand drawn filters section, I was able to find the Astron & Aerovox paper/oil caps; they are ~1" long.  Then jam in those Torwico TW-5669 inductor(s?).  I wonder how Lang was able to jam all those components into those cans?

 

[Biasrocks]

IIRC the cans are physically quite large.

Looking at Biasrocks' hand drawn filters section, I was able to find the Astron & Aerovox paper/oil caps; they are ~1" long.  Then jam in those Torwico TW-5669 inductor(s?).  I wonder how Lang was able to jam all those components into those cans?

 

[creal]

damnyankee, warning!, the hand drawn filters section at page 2 of this post are the Pultec EQPA, not the lang PEQ's filter network
http://groupdiy.com/index.php?topic=43052.20

 

[pucho812]

I have a lang manual in PDF if anyone wants it

 

[creal]

I have a lang manual in PDF if anyone wants it

Pmed

 

[damnyankee]

damnyankee, warning!, the hand drawn filters section at page 2 of this post are the Pultec EQPA, not the lang PEQ's filter network
http://groupdiy.com/index.php?topic=43052.20

I was wondering why the inductance was spelled out on the High Freq and not the Low.  Hmmm...is that a deal breaker for a clone?  I'm going to try to get ahold of ole Cliff to see if he'll talk more about these filters.

And, I've spent a ton of time looking up Lang Electronics.  They made all kinds of recording/broadcast things in the 60s/70s - even mixers.  Lots of ads in old Radio/Recording mags from that eras but as far as finding old gear...nada other than PEQ-2 and PEQ-4 eqs.

 

[damnyankee]

I have a lang manual in PDF if anyone wants it

PM'ed.

 

[creal]

damnyankee, warning!, the hand drawn filters section at page 2 of this post are the Pultec EQPA, not the lang PEQ's filter network
http://groupdiy.com/index.php?topic=43052.20

I was wondering why the inductance was spelled out on the High Freq and not the Low.  Hmmm...is that a deal breaker for a clone?  I'm going to try to get ahold of ole Cliff to see if he'll talk more about these filters.

And, I've spent a ton of time looking up Lang Electronics.  They made all kinds of recording/broadcast things in the 60s/70s - even mixers.  Lots of ads in old Radio/Recording mags from that eras but as far as finding old gear...nada other than PEQ-2 and PEQ-4 eqs.

Look at the Pultec network filter, it's the same typology. The Low section is a simple RC. The inductance in the high freq it used for the bandwidth control.

 

[pucho812]

will e-mail those lang manuals todday

 

[pucho812]

for those looking for the lang manual

http://thehistoryofrecording.com/Manuals/LANG/Lang_Electronics_PEQ-2_instruction_manual.pdf

 

[damnyankee]

I called Cliff /  Electronic Transformer Co who purchased Freed years ago to revisit these High & Low filters.  He stated he remembered we were talking but couldn't recall where the project went (price out making the filter networks).

I told him now we have one of our members' filter network is down - likely due to a bad cap and there's really no way to take apart these cans to repair them.  He agreed with that assessment and I told him these old Lang eqs are still used in studios and run upwards to $2k today and if our guys can't repair them, then they're an expensive door stop.

So, he said he's going to pull the filter info back out if he has paperwork to the part numbers, talk to his guys in the shop to see if they would be interested in making a run of these filter networks.  I told him if he didn't have the info for the part numbers to let me know and I'll get him another set of filters from another Lang EQ because internally they're likely the same and Cliff agreed.

In the event his shop couldn't/wouldn't make them, I asked if he could consider providing us the Filter network schemos since they aren't available anywhere online so we can at least do repairs and he said "Sure".  I gave him my cell # so he can call me directly, anytime.

*fingers crossed*

 

[damnyankee]

Update:

I talked to Cliff/ETC-Freed this afternoon.  He told me he pulled the old archived files on these EQ filters.  He said Lang wrote alot of notes on the filter networks.  He's trying to decipher all that information and said he should have it all sorted out by the end of the week. 

I'm concerned that the original schematics/build didn't work as planned and Lang had to make numerous tweaks to get these filters to function as intended.  I'm wondering if these notes are revisions, then are these revisions the reason there are several different part #s for the filters?  Hmmm...



 

 

[creal]

very great new, damnyankee.
I hope to see these schematic...

Update:

I talked to Cliff/ETC-Freed this afternoon.  He told me he pulled the old archived files on these EQ filters.  He said Lang wrote alot of notes on the filter networks.  He's trying to decipher all that information and said he should have it all sorted out by the end of the week. 

I'm concerned that the original schematics/build didn't work as planned and Lang had to make numerous tweaks to get these filters to function as intended.  I'm wondering if these notes are revisions, then are these revisions the reason there are several different part #s for the filters?  Hmmm...

 

[damnyankee]

I'm sorry Guys - Cliff didn't call me back; I was busy at work that when I had a minute to call, their shop was closed.  I'll try again Monday.  This company does Gov't contract work and I think it should be apparent to all of us that a small run of these filters are out of the question.  So, I'm going to ask him for the schemos on Monday.  Wish me luck!

 

[damnyankee]

Called ETC/Freed this morning.  Cliff is going to pull the 38831 and 38832 filter folders, work up a quote, and call me later this morning.  Also, he said he'll scan the filter schemos and fax them so I gave him my fax number.  More to follow...

 

[damnyankee]

Cliff / ETC is THE MAN!

There are no schemos for the cans.  There's a parts list for what's IN the cans.  Both Low & High Filter cans are dated 6/2/66 and are revised, so this isn't the original set of filters that came with the Lang.  Both cases are 2-5/8" x 2-1/4" x 4" and are filled with HMP potted wax. 

Parts lists for the cans contain the case, cover, MTG boards, grommet for 1/2" hole, single studs, #20 plastic leads. 

- the L.F. Droop Selector and L.F. Equalizer have 14 Self leads and have NO coils and (12) 200V 2% mylar caps (Sprague & Potter)

- the H.F. Droop Selector and Medium &  High Freq Equalizer have 17 self leads and (2) coils and (14) 200V Mica caps (Spragues, to be specific).

Have I piqued your interest yet???

 

[mitsos]

Seems more and more pultec-y.  The original pultecs are said to have had 2 coils in the high boost and later went to one multi-tapped coil. 

Did he also give you the cap values and inductor L values?  Try to get whatever info you can for the inductor, core type or mfg, size, etc, L, and DCR if possible. 

thanks for keeping on this!

 

[damnyankee]

Yes, I got that info - both coils are triple tapped, the list of caps, and all values.  As you would guess, the coils are Freed #36641 and #35542. 

High Frequency uses both coils while the High Droop selector does not have a coil and only uses 6 Mica caps.  Unfortunately, the build does NOT include the board/schemo but the wiring designation is all there so we can compare the images by Biasrocks (Mark) and match up which wires go where on the pots.

I asked Cliff @ ETC/Freed to continue with a quote for the cans.  If it's too costly, I'm sure they can just make the multi-tap coils.

As for Pulteq'y, yes - but with more caps.

 

[damnyankee]

Dan the Man,

I just emailed Abe to see if he would spearhead the Lang.  He and I talked about it ohhh...about 1-1/2 or 2 years ago but I know right now he's knee-deep in his pye comp.  I remember you created the killer front panel for the Lang - so dust that file off...you may be using it here in the near future.

By the way, I love the CLX-160VU panel/case you sold me!!!  A-1 work!!!