Poor Man's Pultec EQP1-A Build Support Thread

[ruffrecords]

I'm probably not the person who should be chiming in on this but looking at your pdf, if viewing the switch from the rear shouldn't your pin 1 be on the left side?

As far as I'm understanding it, the chart you have seems correct but like I said....

Dave

I agree. When fully CCW pin2 should be connected to pin 3.Drawing of pot looks as if it is from the front not the rear.

Cheers

Ian

 

[ruffrecords]

Did I mention that my 18 pos switches are concentric? I also found some seriously cool old Daka-Ware concentric knobs




Dave

Those are some really cool dual concentric switches. Where can I get me some??

Cheers

Ian

 

[rmaier]

Okay, one more time (sorry). Like this?

[Edit: removed attachment]

 

[ruffrecords]

Okay, one more time (sorry). Like this?

I think you changed both the circuit and the pot view so it is still wrong. You need the circuit from the first and the pot view from the second I think. Awww, my head hurts.

Cheers

Ian

 

[rmaier]

Welcome to the perpetual state of confusion that has been dogging my heels since trying to get this right. Sorry - I hope it's not catching...

Okay, one last try...

Ralph

 

[kante1603]

Did I mention that my 18 pos switches are concentric? I also found some seriously cool old Daka-Ware concentric knobs.


Dave

Woooooaaaahhhhh....now that looks really vintage Dave.I wonder how small the inner pot is and if you need much force to turn it.

Very nice,congrats,

Udo.

 

[wave]

Ralph- PDF ver3 looks right to me 

Udo - The inner (smaller) knob is 3/4" or 19mm (for you Europeans). I've worked the switches a little and they are nice and stiff but don't require much force to turn 

My plan is to make a stereo version with concentric stepped controls for the boost/cut and one set of controls for the frequency select (2P6W dual deck switches) Everything will be wired off board

EDIT: I have removed the layout diagram for some editing I will repost when finished

Ian - I emailed you some links  8)

Dave

 

[ruffrecords]

Ralph- PDF ver3 looks right to me 

I think he's got it!


And thanks for the links Dave.

Cheers

Ian

 

[rmaier]

Thanks!

 

[ruffrecords]

Just a quick note to let everyone know that as I have run out of EQP1A PCBs I have just placed an order for a hundred as I still get asked for them occasionally  (PM me). I have also ordered some prototypes of a new Pultec 3 band PCB that combines the poor man's EQP1A and the mid boost/cut mod onto a single PCB. It takes PCB mounting Grayhill switches and off board pots.

Cheers

Ian

 

[wave]

Ian,
That single PCB idea sounds cool! I can't wait to see it!

Dave

 

[dirtyhanfri]

I'm In too for that single pcb

P.D. Finally I got all the parts for the PMEQP1A, and started wiring it. I got not many time to work on it, but I'd like to get this thing working before the summer.

Been lurking this thread lately. Finally I will unbalance the inputs with IC's and use OEP's for the outputs.

 

[ruffrecords]

I'm In too for that single pcb

P.D. Finally I got all the parts for the PMEQP1A, and started wiring it. I got not many time to work on it, but I'd like to get this thing working before the summer.

Been lurking this thread lately. Finally I will unbalance the inputs with IC's and use OEP's for the outputs.

What will you be using for gain make up?

Cheers

Ian

 

[ruffrecords]

Attached is a schematic for the new single PCB based Pultec 3 band EQ. As you can see, the hi boost is as in the original Pultec EQP1A using an inductor. However, I have arranged the circuit so that just by changing capacitor values and shorting out the inductor pins you can build it just like the original poor man's Pultec. As in the poor man's there are 6 hi and 6 lo frequencies and I have added the mid boost/cut option with a set of frequencies chosen from the Pultec MEQ5. The PCB is laid out for Grayhill PCB mounting switches which are quite expensive but you can easily wire up to off board cheaper types.

Cheers

ian

 

[ruffrecords]

Here is a pic of the single PCB Pultec 3 band EQ. The hi boost/cut switch is front left with it capacitors behind i and the (optional) inductor behind it. The mid bboost/cut switch is centre front with it capacitors behind it and the inductor behind them. On the righ front is the lo boost/cut switch with its capacitors behind it and behind that is the pad you need for the EQ in/out switching.

There are no pots on the PCB just the switches which are on exactly the same centres as the Helios EQ version of this PCB. All the pot connections are wired to a triangular shaped trim pot pad footprint in an attempt to make it fairly obvious how to wire each one up to its associated pot.

Cheers

Ian

 

[rmaier]

Wow! Very elegant. If I weren't almost done, I'd be first in line. Brilliant as usual, Ian.
Kudos.

 

[wave]

Ian,
Awesome work as usual!
The 100K resistor between the 4K7 and 0V wasn't on the other mid schematics. I'm assuming it should be there (so I can include it in my layout)?

Dave

 

[ilfungo]

GREAT IAN!!!
I'm IN!!!

 

[ruffrecords]

Ian,
Awesome work as usual!
The 100K resistor between the 4K7 and 0V wasn't on the other mid schematics. I'm assuming it should be there (so I can include it in my layout)?

Dave

The 100K is a nominal value, connected right across the input to the EQ, because this EQ PCB can be used in a number of ways. If you use it just as in the poor man's where it is driven direct from a 10K:10K bridging transformer then you can set it to 12K as in the original to help ensure the transformer sees the right load. If you use it as part of the EZ Tube Mixer then it will probably be driven from a 10K fader so there is no requirement for it to see a specific load and then you would use 100K.

Hope that makes sense.

Cheers

Ian

 

[wave]

Strangely enough Ian, it makes perfect sense! There are all kinds of pennies dropping over here lately thanks to your patience and ability to explain everything to me!

Dave