Lang PEQ-2A clone...RESURRECTED

[damnyankee]

Hi Guys,



      Am I right in thinking that that schemo of the makup amp is seriously flawed . . . . .

Hmmm...I have an image of the amp board and the type of transistors and electro values appear to be correct (I don't have time to check orientation right now but I'll look at that tonight).  At a quick glance, I think at least one (if not more) of those resistor values could be wrong.  Also, I can't read the other 3 caps to see if those are the correct values. 

Hopefully Mark can nab those for us when he pops the hood on his.

DY

 

[Biasrocks]

I'll try to get some pics and measurements and post them here tomorrow.

Am I right in thinking that that schemo of the makup amp is seriously flawed . . . . .

Yep, here's a corrected version.

Mark

 

[creal]

Hi all,

i sent the complet Lang Manual with schematics on the gmail account.
I hope that can help to get a new clone soon

 

[abechap024]

The circuit would not be at all hard to make a one layer self etch type circuit for...
If there is enough interest I will be happy to, if no one else wants to...

 

[creal]

The circuit would not be at all hard to make a one layer self etch type circuit for...
If there is enough interest I will be happy to, if no one else wants to...

it's great, if you can do that

i found other info about the amp
;D

 

[abechap024]

Good Stuff,
Right now I'm just trying to figure out how all the filters fit together. Really looking at those hand drawn filters, they don't quite seem to match up with the  peq-2a's controls...
Am I short sighted here or ??

 

[damnyankee]

Does this help?  It's from the EQP1R...

 

[creal]

thx damnyankee for the schema but i don't think, this one is usefull.
Take a look to the diagram of the LAng, the lang filter is close to the pultec EQPA and not the R version.
We have all the infos needed to build the clone, if someone have free time to work on the pcbs

 

[damnyankee]

I understand, Creal....but to me, that looks like a block schemo of the frequencies as it isn't component specific.  I'd like to see how the parts integrate together and my thought was maybe the example from the EQP1R would help me understand the Lang circuit better (this is my first eq)  

I assume Pultec had a patent on their circuitry and Lang wouldn't be able to directly copy it (and vice versa).  Correct?

 

[abechap024]

Ok let me just some of my thoughts down, maybe it will help me clear some of this....

For the low boost there are 8 selectable frequencies.

For the low droop (love that) there are 4 selectable frequencies.

Now on the hand drawn schems of the filter sections there are 4 caps for the droop and 4 for the boost. They must then add the various caps together via the switches to get the right values...

ok....

yea no matter how I try to do it, I cant seem to make sense of it.

Maybe if someone can open one up and take some pics of the switches and wires

 

[creal]

abechap024, i can help you but i'm very busy this time.
Take a look to the schema of the pultec for the implentation of the different blocs.
Place and replace the value of each blocs in the Lang diagram with the values of the file of the second page of this thread.

 

[creal]

I understand, Creal....but to me, that looks like a block schemo of the frequencies as it isn't component specific.  I'd like to see how the parts integrate together and my thought was maybe the example from the EQP1R would help me understand the Lang circuit better (this is my first eq)  

i'm not expert of Eq, i'm newbie too in DIY, i just make the Gpultec and two pair P2P of the EQPA1 and MEQ5.
Now i have a better hunderstanding of the passives.
I sure the Lang is close to the EQPA, also the EQPA is most easy and clear for learn the different part.

I assume Pultec had a patent on their circuitry and Lang wouldn't be able to directly copy it (and vice versa).  Correct?

i think you're right, Pultec the filter is under copyright.

Cyril
PS: Please excuse my bad english.

 

[abechap024]

Ah ok, Thanks for that.
So I assume we are taking for granted that all the pots and other resistors are going to be pretty much what the pultecs use. cause nowhere can I find resistor values for the lang. Granted they are probably pretty close, but we don't want to assume, otherwise all these carefully crafted cap values will be choosen for nothing cause the frequencies will be off

I think this project needs more info.

 

[creal]

Ah ok, Thanks for that.
So I assume we are taking for granted that all the pots and other resistors are going to be pretty much what the pultecs use. cause nowhere can I find resistor values for the lang. Granted they are probably pretty close, but we don't want to assume, otherwise all these carefully crafted cap values will be choosen for nothing cause the frequencies will be off
I think this project needs more info.

abechap024, do you dowloaded the manual of the LAng?
i sent this one on the Gmail account yesterday.
if not download it, the BOM is on page 14

Go to http://www.gmail.com
Username: groupdiy
Password: thelab

 

[damnyankee]

Fellas,

Did you know Lang is still in business?  They make geetar amps and the PEQ2 (see bottom of page)...

http://langamps.com/

 

[creal]

I did not know, maybe it's because i'm drummer
thanks for the link.

 

[damnyankee]

I called Freed (Electronic Transformer Corp) today and talked to Cliff regarding the 37727 & 37744 EQ Networks.  He pulled the paperwork on them and said the 37727 and 37744 haven't been made in years - since before Freed was purchased.  He also stated there was a company called Lang that inquired about these very items around 6 months ago or so. 

I explained to him what we were doing and told him we weren't sure if the capactors were built in to the EQ Networks or not.  He said he's going to pull the build sheets on them and see what's involved in the build.  I asked him to quote us on a quantity of 25 and 50 if they were doable.

Let's cross our fingers!

DY

 

[creal]

Hi, i'm not surprise for the xfrms, that the old stuff. I have some 1:1 xfrms at home, i'll start by test with these before.
But, if Freed start a new batch of the 37727 & 37744, probably i'll buy them.

For the filter caps i'll use the orange drop or wima. these caps sounds very good.
I've make my pultec clones with the orange drop and panasonic ECP serie, and the sound is great

Cyril

 

[Biasrocks]

I explained to him what we were doing and told him we weren't sure if the capactors were built in to the EQ Networks or not.  He said he's going to pull the build sheets on them and see what's involved in the build.  I asked him to quote us on a quantity of 25 and 50 if they were doable.

Let's cross our fingers!

DY

Cool, why not get them to quote on the full monty. All the transformers are Freed's.

I've got photo's of the guts of my Lang that I'll post shortly. What you will see is that the entire EQ network is contained inside the Freed's, nothing outside except switches, pots & wire for the most part.

Mark

 

[Biasrocks]

Here's the booty.

http://sharktankpro.com/GDIY/LANG/LangPEQ-1a.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-1.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-2.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-3.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-4.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-5.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-6.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-7.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-8.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-9.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-10.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-11.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-12.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-13.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-14.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-15.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-16.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-17.jpg
http://sharktankpro.com/GDIY/LANG/LangPeq-18.jpg

Mark