Poor Man's Pultec EQP1-A Build Support Thread

[ruffrecords]

I am for a few days in Poland and surviving the cold by finally working on the pm eqp1. Of course running in problems right away... Can't read all my docs here... So who knows the relation between the r1-r5 on the power board and the values in the parts list excell file? And what precautions should I take with the 1n4007s? Electrostatic precautions the sticker says... But not how!

Cheers from -18!

Erik

The power supply schematic was done just for this project on the assumption that people would build it point to point as it is so simple. The  power supply PCB uses the same circuit but was designed for a different project so its numbering is different.

R1, R2 and R3 are the 1K 1watt resistors. R4 is 220K and R5 is 75K.

You do not need to take any anti-static precautions with 1N4007 diodes.

Cheers

Ian

 

[wave]

I've been reading this and the other associated threads for this project for about 6 hours and I'm just as confused as when I started today.
I can stare at the diagrams and it just doesn't make sense to me for some reason. I feel like I have Poor Man's EQP-1A block or something. I don't even know where to start with my questions  :-[

Edit: I think I'm starting to get it a little

 

[funkymonksf]

I'm putting together my order and came up with 3 questions. If anyone would advise it'd be appreciated. 1. The switches for the frequencies, are we to use shorting or non shorting? Also if anyone has a part # they've had success with would be nice. 2. Being that the tube pcb has no mounting holes I was curious of your solution. 3. I found omeg pots with the hard to find values easily in Europe, has anyone have a source for the correct values in the states regardless of brand?

Thank you fellow members,
Brice

 

[wave]

I'm putting together my order and came up with 3 questions. If anyone would advise it'd be appreciated. 1. The switches for the frequencies, are we to use shorting or non shorting? Also if anyone has a part # they've had success with would be nice. 2. Being that the tube pcb has no mounting holes I was curious of your solution. 3. I found omeg pots with the hard to find values easily in Europe, has anyone have a source for the correct values in the states regardless of brand?

Thank you fellow members,
Brice

1. I read in one of the other threads associated with this that it didn't matter as the caps had to charge up when you change frequencies
2.Drill it and the chassis and use screws and standoffs
3. Newark in one (a US company) which is part of the element 14 company or whatever stocks them but upon reading the fine print,they come from Farnell UK (another element 14 company) so there is a $20 handling charge and they're non returnable. The US option is to use 5K, 50K, & 500K and tweak the cap values accordingly. You can use Ian's capcalc spreadsheet and plug this in to get the values if you can get it to open (I had a file corrupted error when opening on Excel 2011 Mac and Excel 2007 Windows)

Good Luck!

 

[funkymonksf]

Thank you for the response the pcb mount question I suppose I should have also mentioned I I wt

 

[erikb1971]

I've been reading this and the other associated threads for this project for about 6 hours and I'm just as confused as when I started today.
I can stare at the diagrams and it just doesn't make sense to me for some reason. I feel like I have Poor Man's EQP-1A block or something. I don't even know where to start with my questions  :-[

Edit: I think I'm starting to get it a little

No reason to feel stupid. I have done just a very few number of other projects but this one is a weird one. Technically it is very simple. But conceptually Otis somewhat difficult to grasp. Also, the information is scattered through out a number of threads. And also, Ian is a very very clever guy, and his answers seem to require some amount of technical knowledge to actually grasp. I literally spend about 30 hours sourcing for this project. And still 10% of my items is wrong. The good news is, so far Ian is answering all my stupid questions thoroughly and friendly. Eve the ones I asked per mail because I did not want everyone to see I still did not get it. So keep struggling, keep asking questions, and be So proud when you finish!
I am trying to put together a document as a sort of beginners guide to posh/poor eq, but progress is slow.

Cheers

Erik

 

[wave]

Erik,
Thanks for your kind words sir! You are a gentleman and a scholar!

UPDATE!!!!!
SOme of you may know that I've been having trouble with the capcalc.xls file that is posted around in the different threads.
I have gotten it to open in Excel 2007 in windows on my Parallels virtualizer but it opens with errors and I specifically remember reading that Ian said it calculates to 2 decimal points. Well opening (with errors) the file calculates to as many decimal points as the cell size allows.
I can confirm that it will open correctly in Google Docs!

Still trying my best-

 

[wave]

Question:
When sourcing, is it better to use a combination of cap values to get the total value needed for one frequency point?
I see in Ian's partslist that he uses two cap values  (i.e. 4K C2=10nF + CA=2.2nF) to get the total value needed (12nF)?

EDIT: Would this transformer work for the PSU?
http://www.antekinc.com/details.php?p=671

EDIT#2: If this trafo worked for the mains, what resistors would I have to change? (Dumb a** alert!)
http://www.antekinc.com/details.php?p=638

Still confused-
Dave

 

[wave]

Poor Man's Tube Stage:
Is there a build thread for this?
I'm seeing a spot for a 220K resistor that's not on the parts list spreadsheet, do I populate this or short it out?

EDIT: Does anyone know a U.S. source for a good PCB mount tube socket for this board?

 

[erikb1971]

If there is a build thread, this is it!

 

[wave]

If there is a build thread, this is it!

Haha!
So I'm staring at the PMEQP1AHookup.pdf and I'm wondering is the eq In/Out switch a DPST?

 

[rmaier]

Got my tubes and sockets at Tube Depot. Also a good source for knobs.

 

[MatthisD]

So I'm staring at the PMEQP1AHookup.pdf and I'm wondering is the eq In/Out switch a DPST?

DPDT,  the input signal is one common point to be directed through the EQ or through the pad resistors and at the same time the output signal as the other common, taken from the EQ out or the pad out.

 

[wave]

So this pic could be how I would wire the EQ In/Out switch to do that?

 

[MatthisD]

T2 in place of where you have T3, T3 is connected to the circuit ground using the screen of the cable and connected to the IG pad of the gainstage.

 

[wave]

T2 in place of where you have T3, T3 is connected to the circuit ground using the screen of the cable and connected to the IG pad of the gainstage.

Thanks!. I have such an incredibly hard time understanding schematic style diagrams. It's my diy Achilles Heel. I'm trying to create a layout diagram based on Ian's hookup so I'm sure I will have plenty of questions.

 

[wave]

Well it's another day of feeling stupid but if I don't ask I will never know.
I'm looking at the parts list that Ian posted and I'm wondering a couple things;
In the EQP-1A section, under resistors, it says:
fixed          hi boost R1              5K Lin            0.25W 1%

Is that a typo? R1 on the board is for an axial not a trimmer

Also, it says hi boost R1, hi cut R2, and lo cut R3. Does that mean when I'm populating the hi boost board I put a 5K in the R1 position and jumper  R2 & R3?
Conversely, if I'm building the lo cut board, I populate R3 with a 60K and jumper R1 & R2?

Thanks for the help

 

[rmaier]

Yes, "lin" appears to be a typo, although Ian's xls spreadsheet calls for a fixed value of 4K7 for R1, not 5K.

If you look about half way down page 1 of this thread, you'll see that Ian's jpegs of his populated boards use jumpers (0ohm resistors) in the positions you've mentioned. For the low board, Ian's example is on the back of the PCB.

 

[MatthisD]

Also, it says hi boost R1, hi cut R2, and lo cut R3. Does that mean when I'm populating the hi boost board I put a 5K in the R1 position and jumper  R2 & R3?
Conversely, if I'm building the lo cut board, I populate R3 with a 60K and jumper R1 & R2?

Thanks for the help

The Hi-boost and Hi-cut would presumably be on the same board so R1 4.7k, R2 470R and jumper R3.

 

[wave]

Yes, "lin" appears to be a typo, although Ian's xls spreadsheet calls for a fixed value of 4K7 for R1, not 5K.

If you look about half way down page 1 of this thread, you'll see that Ian's jpegs of his populated boards use jumpers (0ohm resistors) in the positions you've mentioned. For the low board, Ian's example is on the back of the PCB.

Thanks! I think I accidentally changed that (5K Lin) when I was changing the pot values for the standard U.S. pots. I have read this whole thread and I did see Ian's pics, I just wanted to ask the question to double check as I'm trying to wrap my brain around this project and I'm definitely still a noob.

The Hi-boost and Hi-cut would presumably be on the same board so R1 4.7k, R2 470R and jumper R3.

Thanks MatthisD. I think that I'm just over thinking it. That was a stupid mistake on my part 

On the Low board it would be R3=60K (for using U.S. value pots) and jumper R1 & R2?

I had asked this question earlier - Is it better to use two capacitors per frequency to get the necessary value or are two areas provided to use 2 caps to get an odd value (like a value you might not be able to find in 1 cap)?