Poor Man's Pultec EQP1-A Build Support Thread

[theaterguy]

Yeah, the front panel is indeed "finnished".  Jättebra.

 

[G-Sun]

What's the LORLINPULTEC pcbs?
This: https://lh3.googleusercontent.com/MgRF-arOhdafAx1990s94h1LJKO0xf5li3Dt94gQtY6GvkHQamZHu_98judnki4Nz4eLuQ=w1157-h669
?
Does the "Classic Mic Pre V3" replace "Classic Solo v2"?
and work in e.g. a 2U chassis 2ch with the LORLINPULTEC?

Edit: Ok, the solo has onboard psu.

The "LORLIN" and "GRAYHILL": Are these for stepped pots? Can work for 3bandpulteq and Classic gain?

 

[ruffrecords]

LOLINPULTEC PCB is the old PMEQP1A plus the mid board all on one new PCB. Basically it is a V2 version of the PMEQP1A called the PMEQP1A MK2. original design thread is here:

http://groupdiy.com/index.php?topic=59065.msg750451#msg750451

You are right. Classic V3 is EZMixer standard Classic mic pre. Classic Solo is same thing with PSU on one board.

The LORLIN and GRAYHILL are to interface regular PCB mounting Grayhill and Lorlin switches to IDC connectors. Easier to assemble/dissemble than hard wired regular switches. Designed a LONG time ago. All the LORLIN's are gone. Lot's of Grayhills left. There was some talk about a new Lorlin version but not much interest.

Cheers

Ian

Cheers

Ian

 

[G-Sun]

Would you say a 2ch pulteq is suitable for masterbus?

 

[ruffrecords]

Would you say a 2ch pulteq is suitable for masterbus?

Yes, I am pretty sure I have come across articles about people using them on the master bus and I have certainly been asked to include it in a custom design. Assuming you want identical EQ on both the left and the right it would probably best to use stepped pots for accuracy and repeatability.

Cheers

Ian

 

[miszt]

I'm looking at trying my hand at a point-to-point MEQ, but I'd like to start out with an opamp gain stage - and then possibly switch it out for a tube gain stage at a later date;

can someone point me in the direction of a schematic that would work for this idea? (ie so i can switch the opamp for tubes without having to change anything else)

(or even a FET gain stage maybe? but something fairly simple, i don't need gain control except via the filter section)

 

[ruffrecords]

I'm looking at trying my hand at a point-to-point MEQ, but I'd like to start out with an opamp gain stage - and then possibly switch it out for a tube gain stage at a later date;

can someone point me in the direction of a schematic that would work for this idea? (ie so i can switch the opamp for tubes without having to change anything else)

(or even a FET gain stage maybe? but something fairly simple, i don't need gain control except via the filter section)

The easiest solution is to using a FET op amp like the TL072. Here is a link to a simple op amp gain make up circuit. It uses a 2520 but half a TL072 will do fine:

https://drive.google.com/file/d/0B_n67A1hN3qtNzBHSGN5VkIxSFE/view?usp=sharing

It has an unbalanced output but it is easy to convert it to balanced.

Cheers

Ian

 

[ForthMonkey]

Here is my finished Poorman's Pultec!

Big thanks to ruffrecords!

https://www.youtube.com/watch?v=VExQo2mWuXc&feature=youtu.be

 

[ruffrecords]

Here is my finished Poorman's Pultec!

Big thanks to ruffrecords!

https://www.youtube.com/watch?v=VExQo2mWuXc&feature=youtu.be

Cool video. Would you like to send me some pics of the finished unit so I can get Pierre to add them to his gallery of projects based on my desings?

Cheers

Ian

 

[ForthMonkey]

Here is my finished Poorman's Pultec!

Big thanks to ruffrecords!

https://www.youtube.com/watch?v=VExQo2mWuXc&feature=youtu.be

Cool video. Would you like to send me some pics of the finished unit so I can get Pierre to add them to his gallery of projects based on my desings?

Cheers

Ian

Just sent!

 

[miszt]

Would you say a 2ch pulteq is suitable for masterbus?

definitely, i'm using my PQD2 for mastering, and its doing an amazing job, client feedback has been positive all the way

took some effort to match all the components (i decided to go with 0.1% tolerance), but the results where worth the effort; was so impressed (and amazed that i'd actually built the thing lol) i'm now starting an MeQ to go along with it

(agree with the above, stepped controls are the way to go - I also switched out the TOKO inductors for don-audio inductors)

 

[Humner]

finally getting my PM projects finished now I have the inductors.

Here is my mic pre/DI with Ian's Poor Man's Pultec EQP1-A

While Its use will be mainly be in the studio, its first job will be vocal duties during a jam sesh today going into an 80's Yamaha PA.

 

[ruffrecords]

Lovely build. Do you also have pics of the guts?

Cheers

Ian

 

[fragletrollet]

If I wanted to use a CAPI VP312 as makeup gain for the 3band pultec (afaik the same as this one but with included mid and greyhill switches footprints..?), how would I go about?

 

[ruffrecords]

If I wanted to use a CAPI VP312 as makeup gain for the 3band pultec (afaik the same as this one but with included mid and greyhill switches footprints..?), how would I go about?

All my passive Pultec EQ designs need a gain make up amplifier with a high input impedance (preferably at least 40K). They were not designed to feed a low impedance input device like the VP312, so if you want to use one you first need to buffer the output of the EQ with something like a FET follower.

Cheers

Ian

 

[fragletrollet]

Ok. Somehow I imagined I could run the eq into a passive DI, then into the VP`s. Maybe you have a link to a schematic of some sorts? Don`t know what to look for  8)

 

[ruffrecords]

Ok. Somehow I imagined I could run the eq into a passive DI, then into the VP`s. Maybe you have a link to a schematic of some sorts? Don`t know what to look for  8)

Yes, you are quite right, you can use a DI. Once again, a high input impedance is preferable so and active type would be best. However, if you happen to already have a passive DI then it is certainly worth a try. The only problem with a passive DI is noise. The Pultec EQ already has an insertion loss of 20dB. A passive DI will have at least as much insertion loss again so you are looking at a total gain make up of over 40dB. Most mic pres will achieve a noise level below -80dBu at 40dB gain so in theory noise should be OK. The other thing with a passive DI is that the input impedance is not as high as the EQ would like. The effect is a reduction in the range of the bass boost control and an increase in the range of the bass cut control.

The simplest form of gain make up amplifier for my passive EQs is one based on a FET input op amp like the TL072. Attached are a couple of schematics for such a gain make up amp.  One is a split supply version and the other is a single supply version. I will also add the schematic to the documentation for the EQs.

Cheers

Ian

 

[fragletrollet]

Thanks for all the help!  8)

 

[Humner]

Lovely build. Do you also have pics of the guts?

Cheers

Ian

Here is one.

 

[ruffrecords]

Lovely build. Do you also have pics of the guts?

Cheers

Ian

Here is one.

Very nice. Would you like to email a couple of pics to me so I can get Pierre to put them in the gallery?

Cheers

Ian