Poor Man's EQP1A (+MID) Mark 2

[p0ulp]

I had few minutes today to start a basic frontpanel file for this unit, it has not been verified yet and will just be used as a drilling template, I ve measured the main board ( 45mm axe to axe for each rotary switch) , enclosure is 3U .

I will do the silkscreen in my studio, once I have figured out how to make the round scale for pot and switch on photoshop  :

http://www.edouardfranqueville.com/PMEQP1A

 

[ruffrecords]

The white market entry for Peter  Halas, who was making the inductors for this EQ, seems to have disappeared. Did anyone receive their inductors?

Cheers

Ian

 

[shot]

Paid it before summer... and never got it...  ??? huh...
am I the only one?

 

[rock soderstrom]

Hi Ian, no inductors here. I have tried to contact Peter via PM but there was no answer.  :-\ I hope he will find a solution for his issue. If I can help, i will do it. He should just let me know...cheers

 

[Humner]

I have not received mine.

I don't think anyone has received anything.

 

[anjing]

Did not receive mine...

 

[ruffrecords]

OK, I have sent him an email. I'll let you know if he replies. This is very disappointing.

Cheers

Ian

 

[rock soderstrom]

Thanks Ian! Peter has sent me a mail. He said that he will send the inductors this week. cheers

 

[shot]

While waiting for Peter's inductors, I'm starting to compile all the info and components to build two channels of MK2.

I have a question about mains transformer.
Since I already have G-Pultec, could it be possible to use it's mains transformer to power both G-Pultec and two channels of 3band Pultec MK2?
The transformer I have in G-Pultec is custom wound by local workshop with 2x220Vac (2x0.4 A) and 2x3.15Vac (1.5A).
I plan to build HT250 psu and I'm still not sure if I'll do 6CG7 MU or 6922 MU (two of those, since it's dual channel)

Would that transformer be sufficient to provide enough current for all those channels?

thanks!



Luka

 

[ruffrecords]

Thatt transformer should be fine for the HT. The maximum HT current for two channels of PMTGMU will be no more than 25mA. The heaters could be the problem. A 6SN7 heater takes 0.6A so two will need 1.2A. The 6922 only takes 0.3A so two will need 0.6A. You need to add these to the G-Pultec figures to  see if you could use the same transformer to power both simultaneouly. The other problem is that the PMTGMU needs elevated heaters and I am not sure if the G-Pultec would like that.

CHeers

Ian

 

[shot]

Ok, so I'll need to stick to 6922 tube in order to stay within limits of my mains transformer.
G-Pultec uses E88CC (that is equivalent to 6922, right?) in SRPP configuration, so am I right to assume it draws 0.3 amps for heaters, as per datasheet for that tube?

I was checking your document on Tube Gain MakeUp amp configurations and I'll try to stay away from SRPP configuration since I'm hoping to go for lower distortion.
If I build 6922/E88CC in MU configuration, can I use 600:600 or 10k:10k output audio transformer?
I'm asking this since I already have few MCI 600:600 transformers and a few OEP Z3003E 10k:10k ones. Understandably, Id' like to use some of those to avoid spending money on different ones! Is that possible?



Luka

 

[ruffrecords]

Ok, so I'll need to stick to 6922 tube in order to stay within limits of my mains transformer.
G-Pultec uses E88CC (that is equivalent to 6922, right?) in SRPP configuration, so am I right to assume it draws 0.3 amps for heaters, as per datasheet for that tube?

Yes, the E88CC is the same as a 6922. It's heater current should  be 0.3A.

I was checking your document on Tube Gain MakeUp amp configurations and I'll try to stay away from SRPP configuration since I'm hoping to go for lower distortion.
If I build 6922/E88CC in MU configuration, can I use 600:600 or 10k:10k output audio transformer?
I'm asking this since I already have few MCI 600:600 transformers and a few OEP Z3003E 10k:10k ones. Understandably, Id' like to use some of those to avoid spending money on different ones! Is that possible?



Luka

The 6992 mu follower will drive a 600:600 transformer as long as you only load it with a 10K bridging load. I would not recommend using a 10K:10K for the output.

Cheers

Ian

 

[theaterguy]

I have a Lundalh 1540 on input and they recommend 12k parallel on both secondary windings.

http://www.lundahl.se/wp-content/uploads/datasheets/1540.pdf

Should I then left out the 12k to ground resistor at the input?


Also, I'm having my pots 50 -series instead of 47s.  There was somewhere mention of raising values of resistors by 5-6%?

 

[ruffrecords]

I have a Lundalh 1540 on input and they recommend 12k parallel on both secondary windings.

http://www.lundahl.se/wp-content/uploads/datasheets/1540.pdf

Should I then left out the 12k to ground resistor at the input?


Also, I'm having my pots 50 -series instead of 47s.  There was somewhere mention of raising values of resistors by 5-6%?

The LL1540 will work fine. Just use the single 12K across the secondary as shown in the hook up diagram.

Using 50 series pots is fine. You do not need to change any other component values. The tolerance on most pots is 20%  so there is no point in changing other values by a few percent.

Cheers

Ian

 

[MicDaddy]

Hi Ian and guys,

I will roll my own pot core inductors for this project (I have the early version 1+mid boards from a few years back).

Any help finding suitable ferrites in the US?

 

[ruffrecords]

Hi Ian and guys,

I will roll my own pot core inductors for this project (I have the early version 1+mid boards from a few years back).

Any help finding suitable ferrites in the US?

I think the specified Carnhill inductor uses an RM10 core.

Cheers

Ian

 

[MicDaddy]

Huge help, thank you Ian!  I'm off to hunt for materials.

 

[ruffrecords]

Huge help, thank you Ian!  I'm off to hunt for materials.

Farnell do RM10 cores so check out Newark in the USA.

Cheers

Ian

 

[G-Sun]

Looking a little at sizes.
Poor Man's EQP1A (+MID) Mark 2 is 3U wide, or?

Do 2ch, preamp + 3band Pulteq in 2U all stepped seem doable?

Looking here
https://drive.google.com/folderview?id=0B_n67A1hN3qtfnhqS002NUo2WF9OTkZONDNqc3RBTS05SFlWLU4tbWItYVlZc01zejdrbGM&usp=drive_web
there's
3U3bandPultecPCB.png
and
P3B.png

 

[ruffrecords]

The PMEQP1A MK2 PCB is 150mm by 50mm. It is not part of the EZTube Mixer range. It will fit horizontally in a 1U case but don't forget you also need to find room for the pots.

The 3U 3Band Pultec PCB was part of the EZTube MIxer range. It was never made because of the problems containing all the controls inside a standard 3U high module. I will delete it from that folder as it is confusing. The P3B.png is the original 3 band Pultec PCB layout. This pre-dates the lunch box design and is to0 tall to fit vertically  in a 3U EZTube Mixer module. However, it will fit horizontally with ease in a 3U rack box - in fact it will fit in a 1U enclosure.

If you want to do a stereo stepped pot 3 band Pultec you need quite a lot of front panel space.

Cheers

Ian