Build Thread:PQD2

[p0ulp]

populating this one ... also , and looking for the calculation tools, it only concern the low boost/low cut so I guess its the same calculation for the high boost/cut since it's supposed to act as a 10k log/100k log also ? am I right ? it's indicated A/F for the 100k and B/G for the 10k , so that one is ok I suppose.

My question is about frequency and Q ... is there a tools that we can use to calculate those value without having to compute all the filter information (which I am sure would lead me to error as I m not yet comfortable with it) , a tool like harpo did for the neteq maybe ?

Also may I suggest an "offboard" overlay for the cap value just as a pdf to document the build, the overlay can be a little tricky to read

The only thing the calculator does is make sure the total sum is correct and round the resistor values to the E96 ladder (I have to figure out how to make this into E24 some day). I put in the graphs so you can see the log curves, which I know now was a mistake (and really doesn't make much sense). A lot of people think the goal is to get a linear curve going by changing values around. The high cut and high boost are linear, which is why the table simply states the value to put into each, identical step.

When I do another run, I will change the nominators on the board and put in the "default" values from the sheet. They work out very well, and with pre-fixed values. Tinkering with the values for the sake of tinkering with no real idea what the prefix would've done is not really productive imo.

For the high Q/(bandwidth), it might make sense to experiment if you want to measure exact Q values. Personally, I am not someone who is very discerning when it comes to specific Q values, as long as the switch has a throw to it where I can hear the steps working.

Gustav

I think the same, would like to use the "default" value and if needed change for more personnal, no need to change something until you know why and where to go ...

By the way, where are the "default value" ?

I ve checked your peq1a page and the topic related here to find out but I only get several BOM and reference to buy but no link between overlay and different resistor value.

Also, the schem available on your website is really small, I ve also looked at it to find out but can't zoom in as much as I want.



By

 

[Gustav]

I think the same, would like to use the "default" value and if needed change for more personnal, no need to change something until you know why and where to go ...

By the way, where are the "default value" ?

I ve checked your peq1a page and the topic related here to find out but I only get several BOM and reference to buy but no link between overlay and different resistor value.

Also, the schem available on your website is really small, I ve also looked at it to find out but can't zoom in as much as I want.



By

Default values are in the excel file (tip, since its the same values for all 11 slots, its only written once for the linear switches).

If you can't zoom on the schem, one explanation could be that you are not zooming in your PDF reader, but your browser.  The resolution is plenty high, but if I "pinch zoom" on the mousepad on my laptop, everything gets grainy real fast



Gustav

 

[p0ulp]

ok that's clear

 

[Murdock]

Hey, sorry if I missed the info but will there ever be another batch of component kits for the PQD2 Project?

 

[Gustav]

Hey, sorry if I missed the info but will there ever be another batch of component kits for the PQD2 Project?

I had help with the tube portion of the kit of the first run, and sourcing, selecting and matching tubes for something like this is no picnic. In fact, its such a large undertaking, I decided against offering anymore when the selection I had help with ran out.

It also took way too much time to match caps to 1% tolerance for stereo compared to what I felt like the max I could charge for a kit was 

So youre stuck gathering parts yourself,  building the SS version, or hope someone is a big enough ass to copy my PCB design and offer kits.

Gustav

 

[Murdock]

Thanks for the answer!
I decided to gather the parts myself.
And of course I got some questions

Are these specs sufficient for the power trafo:

Primary: 2 x 115v (230v)
Secondary:
220V 0,1A
9V 2,5A
5V 0,5A

Just to be sure, because they vary a little from your power transformer.
And concerning the switch resistors: in your PQD2switches-kit.xlsx file you state "10x 200R (High Q), 10x 100R (High Cut) and 10x 1000R (High Boost)". Just to be sure, I really "just" need ten of each (200R, 100R, 1000R) because these are linear switches?
I read your answer to p0ulp post concerning the same question but did'nt quite understand it...

 

[Gustav]

Thanks for the answer!
I decided to gather the parts myself.
And of course I got some questions

Are these specs sufficient for the power trafo:

Primary: 2 x 115v (230v)
Secondary:
220V 0,1A
9V 2,5A
5V 0,5A

Just to be sure, because they vary a little from your power transformer.
And concerning the switch resistors: in your PQD2switches-kit.xlsx file you state "10x 200R (High Q), 10x 100R (High Cut) and 10x 1000R (High Boost)". Just to be sure, I really "just" need ten of each (200R, 100R, 1000R) because these are linear switches?
I read your answer to p0ulp post concerning the same question but did'nt quite understand it...

Power trafo will probably be fine.

Yes to the question about the switches.

Gustav

 

[miszt]

I'm gathering up components to build one of these myself, but i'm stuck on the inductors, I'd quite like to get something close to the original, but the tap values for the single channel pultec inductors are different for this one - can anyone recommend any?

or do i need to have them custom made? if so, should i get 2 inductors with taps @ 27/47/100mH, and 2 with just 100mH?

or do I actually need individual inductors for each value for this particular design?

 

[Gustav]

I'm gathering up components to build one of these myself, but i'm stuck on the inductors, I'd quite like to get something close to the original, but the tap values for the single channel pultec inductors are different for this one - can anyone recommend any?

or do i need to have them custom made? if so, should i get 2 inductors with taps @ 27/47/100mH, and 2 with just 100mH?

or do I actually need individual inductors for each value for this particular design?

You can wire up a multitapped inductor and figure out alternative mounting if you wish, or you can use the Toko inductors I made footprints for.

Gustav

 

[miszt]

i think i will for now, simpler, and a hell of allot cheaper lol might try the sowters in the future tho


I found some sowter in and out transformers that are supposed to work fine for this, not a massive difference in price compared to the LL5402's, not heard either of them before, from what I've read, the LL5402's are "cleaner"? the sowters closer to the original...have only heard the plugin version so i have no idea what that actually means lol

 

[miszt]

is there any benefit to having 180V rather than 250V coming from the power transformer, or vice vesa?



lol i was just about to buy a power transformer and they are out of stock oops ..cant seem to find anything similar online, any recommendations? (are there any good build threads about this version, or should i just keep reading up on the single channel version?)

 

[miszt]

found a transformer that seems to be the right one (some info on the current capacity in the BOM would be useful, they seem to vary massively, but i got there in the end!)


could still really use a good read up on this tho if anyone has a good link re building it, I'm trying to work my way through ~400 pages of the PeQ thread, but tbh its difficult to pick up the useful info amongst the millions of questions, and I am now even less clear about the build than I was before i started reading lol

 

[Gustav]

I'm trying to work my way through ~400 pages of the PeQ thread, but tbh its difficult to pick up the useful info amongst the millions of questions, and I am now even less clear about the build than I was before i started reading lol

Theres a BOM, theres a board with silk screen, theres a sheet of switch values, theres a schematic, and there is a front panel designer file available.

What do you feel is lacking for you  to move forwards with stuffing the boards, ordering or drilling a panel, casing it, and powering this thing up? Id be happy to help fill the gap, if I can.


Gustav

 

[Murdock]

Happy  new year to you all!
Hey Gustav, would it be possible to use 24 position rotary switches instead of the 12 position ones? If yes, how would I wire this? There are 24 pins on such a switch but only 12 "holes" on the pcb. Would I need to put resistors between the steps and only take pin 1,3,5,... to the pcb?

Also I read somewhere that, if I were to use shorting switches I would need to use bleed resistor between each step. Is that true for the pqd2? And if yes, how much ohm should the resistors have?

 

[miszt]

I'm trying to work my way through ~400 pages of the PeQ thread, but tbh its difficult to pick up the useful info amongst the millions of questions, and I am now even less clear about the build than I was before i started reading lol

Theres a BOM, theres a board with silk screen, theres a sheet of switch values, theres a schematic, and there is a front panel designer file available.

What do you feel is lacking for you  to move forwards with stuffing the boards, ordering or drilling a panel, casing it, and powering this thing up? Id be happy to help fill the gap, if I can.


Gustav

well I've got lots of questions to be honest lol but I feel sure that most have been answered many times already

for eg my previous question about the voltage used for the tubes, is there any benefit to using different voltages? does it affect the dynamic range for eg?

I don't understand the circuit well enough to figure it out myself, i'm coming purely from a recording/mix engineering background, with a vague understanding of the electronics (learnt 20 years ago)


also, apart from physically being 2 pultec filters combined into one PCB, are there any differences between the standard DIY mono pultec that I need to be aware of? or is it exactly the same circuit/components, and I can check voltages in exactly the same way with the same values?

 

[Gustav]

I'm trying to work my way through ~400 pages of the PeQ thread, but tbh its difficult to pick up the useful info amongst the millions of questions, and I am now even less clear about the build than I was before i started reading lol

Theres a BOM, theres a board with silk screen, theres a sheet of switch values, theres a schematic, and there is a front panel designer file available.

What do you feel is lacking for you  to move forwards with stuffing the boards, ordering or drilling a panel, casing it, and powering this thing up? Id be happy to help fill the gap, if I can.


Gustav

well I've got lots of questions to be honest lol but I feel sure that most have been answered many times already

for eg my previous question about the voltage used for the tubes, is there any benefit to using different voltages? does it affect the dynamic range for eg?

I don't understand the circuit well enough to figure it out myself, i'm coming purely from a recording/mix engineering background, with a vague understanding of the electronics (learnt 20 years ago)


also, apart from physically being 2 pultec filters combined into one PCB, are there any differences between the standard DIY mono pultec that I need to be aware of? or is it exactly the same circuit/components, and I can check voltages in exactly the same way with the same values?

Its practically identical, aside from the stepped controls, but maybe seeing this is an isolated project instead of comparing it to the single channel would give you one less issue to worry about!? I dont think theres any need to reference the PeQ1 to build it at all.

You can run it at 180V, but I am not smart enough to calculate the loss of headroom (Most likely a lot less than you might think). I usually aim for 220ish, just because...

Gustav

 

[Vac11]

Hi Gustav,

what is the pitch of capacitors legs on the filters (switches) board? I estimate it´s 7.5 mm....  Or more?

What is pitch of two big 4u7F film caps and two big electrolytic 330uF caps on the "main" board?

Thanks

M.

 

[miszt]

I'm trying to work my way through ~400 pages of the PeQ thread, but tbh its difficult to pick up the useful info amongst the millions of questions, and I am now even less clear about the build than I was before i started reading lol

Theres a BOM, theres a board with silk screen, theres a sheet of switch values, theres a schematic, and there is a front panel designer file available.

What do you feel is lacking for you  to move forwards with stuffing the boards, ordering or drilling a panel, casing it, and powering this thing up? Id be happy to help fill the gap, if I can.


Gustav

well I've got lots of questions to be honest lol but I feel sure that most have been answered many times already

for eg my previous question about the voltage used for the tubes, is there any benefit to using different voltages? does it affect the dynamic range for eg?

I don't understand the circuit well enough to figure it out myself, i'm coming purely from a recording/mix engineering background, with a vague understanding of the electronics (learnt 20 years ago)


also, apart from physically being 2 pultec filters combined into one PCB, are there any differences between the standard DIY mono pultec that I need to be aware of? or is it exactly the same circuit/components, and I can check voltages in exactly the same way with the same values?

Its practically identical, aside from the stepped controls, but maybe seeing this is an isolated project instead of comparing it to the single channel would give you one less issue to worry about!? I dont think theres any need to reference the PeQ1 to build it at all.

You can run it at 180V, but I am not smart enough to calculate the loss of headroom (Most likely a lot less than you might think). I usually aim for 220ish, just because...

Gustav

thanks, well my only reason for referencing the other project is that this one seems fairly new, so if the circuits are identical, there are probably lots of answers to my questions in the mono version

great thanks, I'm using 220V aswell (the don-audio one which is supposed to be for mono pultec, but using googles Cache function, it seems to have a higher current rating than the one which was on your website - those current ratings would be mighty useful for people i'm sure if you included them in the BOM )

 

[Gustav]

Hi Gustav,

what is the pitch of capacitors legs on the filters (switches) board? I estimate it´s 7.5 mm....  Or more?

What is pitch of two big 4u7F film caps and two big electrolytic 330uF caps on the "main" board?

Thanks

M.

Capacitors on the filter board are 5mm. Theres a board layout file, and you can use that to check the other two

Gustav

 

[Gustav]

Hey Gustav, would it be possible to use 24 position rotary switches instead of the 12 position ones?

No, it would be a much bigger job (and mess) than just wiring the filter circuit P2P directly on switches.

Also I read somewhere that, if I were to use shorting switches I would need to use bleed resistor between each step. Is that true for the pqd2?

All you need to do is populate the PCB as is.

Gustav