Poor Man's Pultec EQP1-A Build Support Thread

[ruffrecords]

Sorry Ian. Yes I meant 12mv when output is connected and 58mv when disconnected.

OK, 58mV is close to what I would expect. So it seems something in your gain make up amp is pulling down the output.

Cheers

Ian

 

[duantro]

Sorry Ian. Yes I meant 12mv when output is connected and 58mv when disconnected.

OK, 58mV is close to what I would expect. So it seems something in your gain make up amp is pulling down the output.

Cheers

Ian

YEEEES! I found it! It was VR1 and VR2 were in the opposite spots. I started thinking when reading Dirtyhanfri's comment about the low cut being really wide bandwidth and like a volume control. Thanks for all of your help Ian. I thought for sure I botched the switch hookups and never thought of the simple makeup gain boards. I'l post pictures after I get it all buttoned up in a few days.

 

[ruffrecords]

YEEEES! I found it! It was VR1 and VR2 were in the opposite spots.

Wooohoooo!

Cheers

Ian

 

[duantro]

I took it to the studio and it sounds great! Mid cuts are subtle as noted in the thread previously.
So glad I finally finished this thing. I had many hurdles to jump, all due to lack of knowledge on my part. However, I am learning so much! Thanks again Ian!

Hurdle #1- I used my FPexpress file from my PM670 as a template to start. Unfortunately the enclosure had different width spacing for front panel mounting, i.e. die grinder to elongate mounting holes. This really bummed me out, since Don-Audio did a killer job on the front panel!

 

[duantro]

Here's a blurry guts shot.
Hurdle#2- When I made my fpexpress file I had the frequency pcb's 1/8" too close to the bottom of the case. So I had to flip some switch pcb's on their side and extend the others to fit. It was real tricky, even with a hakko 808, to desolder the switches that I needed to extend. This was also real fun while trouble shooting... Ha!

 

[mikeyB]

I took it to the studio and it sounds great! Mid cuts are subtle as noted in the thread previously.
So glad I finally finished this thing. I had many hurdles to jump, all due to lack of knowledge on my part. However, I am learning so much! Thanks again Ian!

Hurdle #1- I used my FPexpress file from my PM670 as a template to start. Unfortunately the enclosure had different width spacing for front panel mounting, i.e. die grinder to elongate mounting holes. This really bummed me out, since Don-Audio did a killer job on the front panel!

Hi Duantro - what is the function of the "SHIFT 1/2" switch?

 

[duantro]

I took it to the studio and it sounds great! Mid cuts are subtle as noted in the thread previously.
So glad I finally finished this thing. I had many hurdles to jump, all due to lack of knowledge on my part. However, I am learning so much! Thanks again Ian!

Hurdle #1- I used my FPexpress file from my PM670 as a template to start. Unfortunately the enclosure had different width spacing for front panel mounting, i.e. die grinder to elongate mounting holes. This really bummed me out, since Don-Audio did a killer job on the front panel!

Hi Duantro - what is the function of the "SHIFT 1/2" switch?

It's the mod that Surfkat suggested back 10 pages or so. Adds a cap to shift the frequency of low cut and high boost. Seems to widen the cue some, when cutting and boosting. 

 

[mikeyB]

Thanks - i'll read through it.

 

[JohnWatkins]

I know this has been discussed a lot, but I just want to double check.  Thanks for your patience.

I'm wiring up my pots (getting close - very exciting) and I wonder if someone can just verify for me that I'm making a correct translation from Dave's wiring diagram of normal boost/cut pots to my 12-position Lorlin stepped pots.  By my measurement, I think that pin 12 should be in the place of the right lug (looking from the rear), pin 1 should be in place of the left lug, and the center pin of the switch should go in place of the center lug of the normal pot.

For reference, turning the switch all the way ccw gives me the max resistance between pin 12 and the center pin of the switch.  Hope that's right or I've got a LOT of soldering to undo. 

Thanks in advance for any help.

 

[duantro]

I know this has been discussed a lot, but I just want to double check.  Thanks for your patience.

I'm wiring up my pots (getting close - very exciting) and I wonder if someone can just verify for me that I'm making a correct translation from Dave's wiring diagram of normal boost/cut pots to my 12-position Lorlin stepped pots.  By my measurement, I think that pin 12 should be in the place of the right lug (looking from the rear), pin 1 should be in place of the left lug, and the center pin of the switch should go in place of the center lug of the normal pot.

For reference, turning the switch all the way ccw gives me the max resistance between pin 12 and the center pin of the switch.  Hope that's right or I've got a LOT of soldering to undo. 

Thanks in advance for any help.

Hey JohnWatkins,
I believe I have my Lorlin's wired up as CCW = 0r, and connected as the left lug of the pot, in the image (from the rear), of Dave's diagram. Conversely, CW = max resistance and connected as the right lug of the pot in Dave's diagram.
Hope this helps.

 

[duantro]

Gentlemen,
I have created a diagram for my stepped switches (I need these visual aids) and I'm wondering if you can give it a look and make sure that I'm going to do this right.
The switch is viewed from the front (shaft) side and I have labeled the connections as Pin 1 Anti CW...etc.



So if looking at my diagram, if I were using this switch as the Hi Boost Lin pot (switch) then Pin1 would be connected to T1 of the High PCB.
Pin 2 would be connected to T2 of the High PCB. Pin 3 would be connected to Pin3 of the Hi Cut switch, correct?

Conversely, if this were the Lo Boost Log pot (switch), Pin 1 would be connected to T1 of the Lo PCB while Pin 2 would be jumpered to Pin 3 and Pin 3 would be connected to T2 of the Lo PCB as well as Pin 1 of the Hi Cut pot (switch).

Does this sound right? Basically I'm trying to make sure I'm connecting the wires correctly to the switch (pot).

Thanks
Dave

JohnWatkins-I used this as a reference post #308

 

[ruffrecords]

I took it to the studio and it sounds great! Mid cuts are subtle as noted in the thread previously.
So glad I finally finished this thing. I had many hurdles to jump, all due to lack of knowledge on my part. However, I am learning so much! Thanks again Ian!

I am really pleased we finally got that sorted out. At least it turned out to be something simple in the end.

Do you think you could email me some pictures to add to my projects gallery?

Cheers

Ian

 

[JohnWatkins]

Thanks Duantro.  I'm pretty confident now that I'm thinking of it correctly.  Time will tell, right? 

 

[duantro]

Ian- Photo's are headed your way! Thanks for helping me thru this stupid mistake. It truly sounds great and so smooth! I'm getting a small buzz from the right channel. I think it may be from the AC power switch being so close to the High frequency pcb and wiring. I may have to make a tube shield like forum member Kingston has done with his (p)m670.

JohnWatkins- look over these diagrams again. It sounds like you may have the Lorlin's resistors strung around the wrong way. In the switch diagram, from post #308, when flipped horizontally and viewed from the back, pin 1(on the right bottom) to center wiper pin should = 0 r. Daves switch diagram that I posted above, from post #308, is pictured as viewed from the front.
IF you are using Dave's hookup diagram, then 0r is on the left lug of pots.

 

[JohnWatkins]

Duantro, thanks for double-checking.  I think we're maybe talking about the same thing only viewed a different way.  You're saying pin 1 should go to the left lug on the diagram and I'm saying pin 12 should go to the right.  Same thing, no? 

Unless I'm thinking of it incorrectly, the pins on the switch that represent minimum and maximum resistance are determined by the construction of the switch and the resistors can only be wired to it in one way (for a linear pot).

Am I confused?  Ian?  Dave? 

 

[JohnWatkins]

I measured a regular pot and all of the resistance is on the right (viewed from the rear) when fully ccw.  When measuring the stepped switch, all the resistance is at pin 12 when fully ccw.  That's how I came up with my earlier determination.  Please let me know if I'm wrong.  Thanks.

 

[duantro]

I measured a regular pot and all of the resistance is on the right (viewed from the rear) when fully ccw.  When measuring the stepped switch, all the resistance is at pin 12 when fully ccw.  That's how I came up with my earlier determination.  Please let me know if I'm wrong.  Thanks.

Ok yes you are correct. In daves hookup drawing, 0r is on the left lug of pot. I was referring to the switch diagram, if it was flipped horrizontally, and viewed from the back, when i said on the right. This is what confused me on many things- too many different diagrams that aren't viewed the same way or are for different wiring.
So you should be good, and sorry for the confusion!
I edited my previous post, so it clarifies which diagram I was referring to, in hopes to clear up any further confusion here.

 

[ruffrecords]

@Duantro,

I got the pictures OK this time. Looking good.

Cheers

Ian

 

[ForthMonkey]

Hi,

Can i use 50K,5K,500K instead of 47K,4.7K,470K?

 

[duantro]

Thanks Ian!

Forthmonkey- short answer is yes. Read post #17 on the first page.