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General Discussions => The Lab => Topic started by: khstudio on October 03, 2008, 02:28:16 PM

Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 03, 2008, 02:28:16 PM
My 3 DUAL PULTECs - EQP-1a3 - Solid State.

Special Thanks to DRPat for his great advise & helping me thru this!!! :thumb:
Also, special thanks to TAT for sharing the files for his face-plates... I just modify them for my needs.

(http://www.twin-x.com/groupdiy/albums/userpics/3-Pultecs-7.jpg)

All 3 use the JLM Hybrid circuit for the input buffer - See Topic Here:
PULTEC - Input Options -Buffers- Imp - TX - JLM Hybrid opamp
http://www.groupdiy.com/index.php?topic=26790

ALL Face Plates are "Vinyl Stickers"
I'm lucky because my brother works at a sign company & can make these for me. The machine he has also cuts ALL the holes for me.

The BLUE one uses API 2520's, HS-56v TX for the output, Original-Iron powder core - toroidal Inductors (wound by me) & also has a switch on the front panel to choose between "Class A or AB" on the HYBRID Circuit. Caps for the High Boost are mixed - I tried to follow the "Type" the original used @ certain frequencies (Posted by DRPat) All other caps are WIMA's for LOW Band's & PANASONIC Stacked metal film for High Cut

The RED one uses YAMAHA 80200 DOA, Tamura TX for the output, Ferrite toroidal Inductors (wound by me) & also has a switch on the front panel to choose between "Class A or AB" on the HYBRID Circuit. Caps for the High Boost are ALL Polyester - All other caps are WIMA's for LOW Band's & PANASONIC Stacked metal film for High Cut

The BLACK one uses API 2520's, HS-56v TX for the output, Cinemag Inductors, Styrene caps for High Boost & PANASONIC Stacked metal film everywhere else.

Here's some LARGER PICs:::::::::::
http://www.twin-x.com/groupdiy/thumbnails.php?album=243

The BLUE one

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Blue-Pultec-Front.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Blue-Pultec-Top.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Blue-Pultec-Back.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Blue-Pultec-Hybrid.jpg)

The RED one

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Red-Pultec-Front-3.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Red-Pultec-Top.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Red-Pultec-Back.jpg)

The BLACK one (Pics are Older & don't show the New HS-56v or Hybrid)
(http://www.twin-x.com/groupdiy/albums/userpics/normal_Pultec-Front-1.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Pultec-Inside-1.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Pultec-Inside-Left.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Pultec-Inside-Right.jpg)

(http://www.twin-x.com/groupdiy/albums/userpics/normal_Pultec-Filter-Board-1.jpg)
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: 3nity on October 03, 2008, 03:00:03 PM
They look nice!!
Do all the output boards are the same with only change in the DOAs and surround circuit?

BTW wich colour uses the 2520 and Tamura output??

I'm tempted by pultecs man!
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 03, 2008, 03:54:22 PM
The BLACK one is was my 1st build over 6 months ago when I didn't have any HS-56's.
I went thru a lot of trial & errors concerning the input setup... most of which is detailed in THIS THREAD - LOTs of good info & feedback from many, including Pat & Joe from JLM:
http://www.groupdiy.com/index.php?topic=26790

After getting some HS-56's... I put a pair in the BLACK & the BLUE one.
The RED unit uses the YAMAHA DOA (which runs on 24v, along with the Hybrid) & the Tamura OT.
Surprisingly, this unit sounds GREAT!!!
Actually, they all sound great... just different.

I don't think you can go wrong with the Pultec circuit PERIOD!

Just use some good components & listen to it in Bypass... this shows you what the AMP circuit is doing to your signal... if that's good & the EQ circuit is built correctly, you'll be happy.  :green:

I chose to use the Hybrid on the front end because of the Loading issues you can have, especially trying to drive the Pultec circuit with "Modern" (10k) gear.
The Hybrid has a FET input so it can handle my 10k insert point on my console or anything plugged in without a sweat... YES, there is a little different sound compared to the TX input, which is more interactive with what's driving it but I did a lot of back & forth testing/listening & myself & a few friend/customers all chose the Hybrid + it made it much more universal & less of a headache by not having to worry if the devise before the Pultec could drive it correctly. As I meantioned, the Hybrid has the added bonus of the chose of being Class A or AB... which adds a nice change of flavor.
I DID NOT USE THE DC SERVO ON THE HYBRID!!!
It was NOT needed. Joe also commented about this in the other thread!


Original EQP-1a3 SS output Circuit (Drawn by DRPat from an original unit):

(http://i74.photobucket.com/albums/i276/velvettone/EQP-1A3Schematic.jpg)

JLM Hybrid:
http://www.jlmaudio.com/JLM%20Hybrid%20opamp.htm

http://www.jlmaudio.com/JLM%20Hybrid%20Opamp%20circuit.pdf


Notes from Hybrid Thread:

Quote
I'd like to try & set it up like Matt did... replacing the 600:600 input
Transformer with the JLM Hybrid.
[Joe] ok see attached gif. It is as simple as that.

(http://www.twin-x.com/groupdiy/albums/userpics/Simple_Balanced_in_buffer.gif)

Should I add the 620 ohm resistor to GND - between the JLM Hybrid &
Pultec's Hi Boost Pot? (Like the original)
[Joe] NO the hybrid gives a zero ohm output so no load resistor is needed.

Are any other caps needed ???
[Joe] No if you have DC noise on any of the passive EQ pots either fit 2 x
22uF input caps or 1 x 470uF output cap or turn on the Hybrid DC servo. You
only need to do one of these things but none should work just fine.

Last question - Can I join pins 1 & 3 when hooking UN-Balanced gear to
the JLM Hybrid's input ???
[Joe] Yes

Thanks Again,
Kevin
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 03, 2008, 04:07:13 PM
Very nice Kevin  :thumb:

Can't wait to try out those hs56's  :grin:



EDIT: at what voltage are you running your 2520's? They can handle a 24V dual supply right?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 03, 2008, 05:15:14 PM
Quote from: "3nity"
They look nice!!
Do all the output boards are the same with only change in the DOAs and surround circuit?


YES. I designed these cards to be universal... many ways to set them up... line amp, Pre, etc...
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: skal1 on October 03, 2008, 06:01:35 PM
yes yes love those cases, now i wish i made my own ,where did you get ya case from
 
 :green:  :green:  :thumb:

regards

skal1
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: gevermil on October 03, 2008, 06:23:10 PM
wow.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 03, 2008, 07:15:56 PM
Quote from: "skal1"
yes yes love those cases now i wish i made my own ,where did you get ya case,

 :green:  :green:  :thumb:

regards

skal1


Read 1st post.  :wink:
Cases are Par-Metal. Face is a Vinyl Sticker... design is modified from Tat (Purusha's) Original design... which is modeled after the Manley's.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 03, 2008, 07:19:54 PM
Quote from: "gevermil"
wow.


 :green:
Yes, they're nice... but a sh*t load of work, research & designing.

Every Cap, Resistor, Pot, etc... was measured and matched for balance of the 2 channels in each unit.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: ruairioflaherty on October 03, 2008, 08:11:10 PM
Quote from: "radiance"
EDIT: at what voltage are you running your 2520's? They can handle a 24V dual supply right?


+/- 20V is the max for a 2520, several forum members have fried theirs trying to push it further.  Reading comments from PRR and SSLtech in various threads leads me to believe that the risk of destroying a nice opamp is not worth the tiny headroom gains. I plan to run my 312 at +/- 18V.

I've emailed you the 2520 datasheet, I think I got it from Dan Alexander's site if anyone else is looking for it.

Cheers,
Ruairi
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 03, 2008, 08:29:00 PM
Thanks Ruairi  :thumb:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 03, 2008, 10:17:36 PM
I run ALL my 2520's (Peter/Fabio's) @ +/- 18v.

The RED unit with Yamaha 80200 DOA's is @ 24v.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: bluezplaya on October 04, 2008, 12:51:20 AM
Them's dope. Now you've got six channels of EQ just waiting to be patched as inserts on the Topaz. Hey Kev, would you be interested in looking at a Yammy schematic for me?

Sweet build.  :guinness:
Adam
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 04, 2008, 02:43:09 AM
Quote from: "bluezplaya"
Them's dope. Now you've got six channels of EQ just waiting to be patched as inserts on the Topaz. Hey Kev, would you be interested in looking at a Yammy schematic for me?

Sweet build.  :guinness:
Adam


I'm finishing soldering the patchbay cables right now. :green:

What for, PM1000? I'm semi familiar with the channels but not the rest of the board... same goes for the PM2000.

Hopefully it's not in need of another run of late night, 2 hour + troubleshooting sessions over the phone.  :razz: i kid i kid.
I've noticed your posts & can see you've come a long way since we talked a long time ago. :thumb:

I'll try to help if I can. I've got a STACK of DIY to finish & not much free time:

3 Pultecs - DONE
Sontec EQ - 80%
PM670 - 50%
SSL 9k (4ch) - 20%
NYD 1 Bottle - 50%

It's been a LONG summer building... I'm gonna take a loooong break from DIY & get back to making music (for myself) when this sh*ts done + my racks are FULL! ... still got sessions 3-5 days a week too.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: bluezplaya on October 04, 2008, 02:49:54 AM
It's my Yamaha M1516. I'm trying to beef up the master channels and don't know if I need to breadboard some circuits with vintage opamps, or IC's or discrete stuff or what.

Here's the thread: http://www.groupdiy.com/index.php?topic=29725&highlight=m1516
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: Viitalahde on October 04, 2008, 08:27:41 AM
Now that gets my approval!  :thumb:  :wink:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 04, 2008, 08:34:53 AM
Quote from: "khstudio"
... I'm gonna take a loooong break from DIY & get back to making music (for myself) when this sh*ts done.....


 :green:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: bluezplaya on October 04, 2008, 12:37:57 PM
Hey Kev, I have two Pultecs that I've built..one with a Telefunken diamond tube and iaudio's custom wound inductors. The other one needs some work to it. I't's not producing gain in the output stage. However, after checking out your builds I have now seriously considered changing the output to solid state by way of a green pre PSU (+/-15v) and a Melcor 1731. Would this work? I've already got the filter boards working (Gyraf) and using Edcor XS1100 ins and outs.

Thanks,
Adam
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: 3nity on October 04, 2008, 12:43:56 PM
It will work! either with PeterC psu or something else....as long as the 325 (line amp) circuit works!...
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: bluezplaya on October 04, 2008, 12:47:00 PM
I don't have a line amp. I have a PSU, a Melcor 1731 opamp, and a Radio Shack breadboard!  :green:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 04, 2008, 12:59:19 PM
Kevin

Fantastic work there. Thanks for sharing your experiences with this.

questions : many

1. Would you offer any vinyl panel services - just curious. Or can this be
found anywhere for front panel graphics.

2. looks like you used some polystyrenes in the filter section , are these preferred over polypro's or polyester orange drops or does the original
use polystyrenes.

3. Any difference in filter section in using a hand wound homebuilt torroid inductor as compared to say a production made one from a brand name maker.  or is it just a cheaper way to get the real deal. By the way is the original inductor made the way you have yours done ?

4. Are the pots 2 watters, conductive plastic or carbon element ?

5. Is there a original eqp1a3 schematic available to post here for reference ?

6. how do you compare the Tamura version to the triad56 version
    tone, body, frequency emphasis on overall sound ? What Yamaha
    unit are those outputs from ? I have some outputs from a Pm1000
    but there not as robust in size. wondering if the pm1000 outputs are
    too small. I believe there 1:1's

thanks again  :thumb:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 04, 2008, 01:04:15 PM
Quote from: "maxwall"


5. dou you have a original eqp1a3 scematic to post here for reference ?
:


There is no original eqp1a3 (solid state version) schematic.

That's what Dan Alexander told me.....
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 04, 2008, 01:08:40 PM
Radiance,

the original exists, I have seen it with my own eyes, but I can't find it right know. was hoping someone had it within a minutes reach.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: bluezplaya on October 04, 2008, 01:12:55 PM
(http://i74.photobucket.com/albums/i276/velvettone/EQP-1A3Schematic.jpg)

This is on the first page of the thread. Don't know if that helps.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 04, 2008, 02:24:23 PM
Bluezplaya,

Yes I saw this already , but I was'nt sure if there were any mods here that departed from the original schematic.

Funny thing , whenever a pultec schematic is posted the filter block section is always left out - this is important to have as well.

Does any one have a the filter block details in schematic form ?

Also I don't see any pots in the schematic, could those be in the filter block section ?

The power block is just a off the shelf regulated bi-polar - easy
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 04, 2008, 04:47:20 PM
Quote from: "maxwall"
Kevin

Fantastic work there. Thanks for sharing your experiences with this.

questions : many

1. Would you offer any vinyl panel services - just curious. Or can this be
found anywhere for front panel graphics.


I do have a few spare stickers for both versions I MAY sell off.

Quote
2. looks like you used some polystyrenes in the filter section , are these preferred over polypro's or polyester orange drops or does the original
use polystyrenes.


The original uses a MIX:
off the top of my head-
3,4 & 5k = Styrene
8, 10 = Paper
12 & 16 = Silver Mica

This is how I did my BLUE unit (which I tried to make as close as possible to original, EXCEPT the input section)

Black unit = all Styrene (maybe more "accurate" sounding)
RED = All Poly  (maybe more "smooth" sounding)

They both sound good... just different.


Quote
3. Any difference in filter section in using a hand wound homebuilt torroid inductor as compared to say a production made one from a brand name maker.  or is it just a cheaper way to get the real deal. By the way is the original inductor made the way you have yours done ?


Yes,
The Iron powder core ( I wound & used in my BLUE vers) is exactly like the original. Over 1300 turns each. I was lucky to get a pair of these. They're VERY hard to find & I couldn't begin to tell you where to find them.
They have a different sound compared to the Cinemags, which are CLEAN & Accurate! The Ferrite Toroidals I wound for my RED version are closer to the original... The toroidal cores seem to "Bloom" or spread more harmonics somehow, they add a "Grit" or flavor to the sound that the POT CORE's, like Cinemags, don't. But I DO like them BOTH!!! for different reasons.

I have some extra Ferrite Toroidal cores that I may wind & sell.

Quote
4. Are the pots 2 watters, conductive plastic or carbon element ?


Nope, Alpha's = CC

Quote
5. Is there a original eqp1a3 schematic available to post here for reference ?


The 1a3 filter section is the same as the tube versions except the output section which I posted.

Quote
6. how do you compare the Tamura version to the triad56 version
    tone, body, frequency emphasis on overall sound ? What Yamaha
    unit are those outputs from ? I have some outputs from a Pm1000
    but there not as robust in size. wondering if the pm1000 outputs are
    too small. I believe there 1:1's


Too hard to explain. Like I said before, I don't think you can go wrong with this circuit... just build it then listen. You'll never know until you here for yourself what the different parts do to the sound... they can ALL be cool.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 04, 2008, 04:58:23 PM
Quote from: "bluezplaya"
Hey Kev, I have two Pultecs that I've built..one with a Telefunken diamond tube and iaudio's custom wound inductors. The other one needs some work to it. I't's not producing gain in the output stage. However, after checking out your builds I have now seriously considered changing the output to solid state by way of a green pre PSU (+/-15v) and a Melcor 1731. Would this work? I've already got the filter boards working (Gyraf) and using Edcor XS1100 ins and outs.

Thanks,
Adam


I would try it... you can always drop in different DOA's.
If you build the make-up amp like posted - I'd change the 1.47k (fixed gain) resistor to a 5k trimmer so you can adjust for unity gain in bypass.

OR

Build a line amp, like the API 325.

If built correctly they'll all work.

There's a schematic around here for the M-tec (Manl*y version)
which uses a 100k on the output... this is what I did.(EDIT - WRONG, NO I Didn't use the 100k - I kept it stock & followed DRpats schematic for the filter section... there's a thread about this somewhere, I used a 10k)
I think it may have something to do with the SS output compared to the tube & removal of the "interstage TX"
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 05, 2008, 04:21:11 PM
HS-56 Note (FOR THOSE THAT ARE USING HS-56 ON THE OUTPUT):!:

Look at the output amp I posted (from Pat).

The INPUT HS-56 on the SS Pultec is wired "Normal" = Primary IN, Sec to filter.

But on the OUTPUT, the HS-56 is Backwards!!!

& it also has a 1.8K LOAD!
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 05, 2008, 06:00:13 PM
Quote
The 1a3 filter section is the same as the tube versions except the output section which I posted.


Where is the Pultec passive filter section posted ?

I know its the same as the EQP1A , but I have'nt seen it in schematic form
can this be put up here for reference, even a link would be fine.

How would one indentify an iron powder inductor core for using to make their own pultec authentic inductor. Are there any markings or identifiers on the core ?  any possibility we can see a closeup pic of one ?


thanks.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 05, 2008, 07:00:01 PM
Quote from: "maxwall"

.. a link would be fine.
.


http://www.gyraf.dk/gy_pd/pultec/pultech.gif
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 05, 2008, 08:55:09 PM
Quote from: "radiance"
Quote from: "maxwall"

.. a link would be fine.
.


http://www.gyraf.dk/gy_pd/pultec/pultech.gif


Not a Pultec!

The Gyraf schematic/version is actually from the TUBE TECH - Pultec.
It's close but...
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 05, 2008, 11:22:25 PM
KHStudio, Radiance

thanks, this helps :thumb:

What are the physical dimensions of the original inductor core  ?

its just a iron magnetic ring , yes ?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 06, 2008, 12:20:11 AM
http://www.groupdiy.com/index.php?topic=25482&postdays=0&postorder=asc&highlight=inductor&start=15
http://http://www.groupdiy.com/index.php?topic=26322

I asked Pat to comment here when he gets a chance. He's very busy.

I know he posted some info & possibly a schematic of his filter circuit but I can't find it or nor do I have time to look for it right now.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 06, 2008, 06:08:06 AM
Quote from: "khstudio"

Not a Pultec!

The Gyraf schematic/version is actually from the TUBE TECH - Pultec.
It's close but...
:


Are you sure ???  Gyraf has two schematics posted on his website.
One is for his DIY version and the other one (the one from which I posted the link) is a redrawn version.

Quote
Thanks to Chris Jenrick for sharing the "real" filter schematics for reference.


Either way, don't expect big differences between the two besides frequenties and different ways of implementing rotary switches.

See it as a couple of basic passive EQ parts patched together in a certain way. If at all, ther're limited ways of doing such a "patchwork" .....
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 06, 2008, 06:54:08 AM
It says TUBE TECH right on it. :wink:

You are correct about different ways to get to the same point but there are a lot of elements that add up to the "Pultec Sound".
Also, I think the original questions was about a REAL Pultec schematic.

Like I said... all my units are set up a little different & I like them all for different reasons...
but after winding the original inductors & setting up the filters/caps to match, building the output amp like Pats SS Pultec with 2520's, 1uf CDE input caps & military sealed 150uf tantalum's on the output of the 2520 & HS-56 on the output with proper 1.8k loading - the EQ sounds VERY cool, I can't begin to describe it... it just adds weight to the low end & a completely different Hi Boost sound that the others (like the Cinemag vers) the Ferrite toroidal is much closer but still not the same.

EVERYTHING that I listed above changed the sound.
& note that MOST are in the "signal Path" (Amp section/Bypassed signal) as opposed to the "Filter section"

BTW... on the REAL Pultec, the 16k shares the same tap as the 8k.

I know Pat posted the Tap Values. I'll try to dig them up & post them if he doesn't.

I'll say it one more time... If your bypassed signal sounds good & your filter sections are built & work properly, you can't go wrong with ANY version... it doesn't have to be exactly like a Pultec to be a great "Passive" EQ.  :green:

My RED unit with Yamaha DOA's, 470uf FC's instead of the Tants, 1uf SOLEN's instead of the CDE's, Tamura OT's & self wound Ferrite toroidals is KILLER too.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 06, 2008, 07:03:37 AM
BTW... Joe Malone from JLM posted a schematic he drew up from 3 different Tube Pultecs. It says "Hosef" or something on it & is ALSO a great reference.
It does differ from Pat's Pultec so it seems there were "some" variations.

But I was interested in the SS version & that Pat reversed from his original units.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: radiance on October 06, 2008, 08:22:27 AM
Quote from: "khstudio"
It says TUBE TECH right on it. :wink:
.


did not see that  :oops:

strange...Jakob never mentioned Tubetech other than on the schematic  :?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 06, 2008, 05:15:56 PM
Well, I saw the 'Hosef' schematic too. But I have to take all the schematics lightly, until I see the original pultec one.

A real pultec passive filter schematic would help a lot. All the other passive inductor based filter sections I've seen are DIY versions that have some variance as kevin pointed out or what is not considered to be the original. I want to have the original to establish some kind of concrete baseline for my up coming builds. without it , it seems I'm not starting the project with any meaningful direction.


I have a local source here for vintage inductor cores that I think might have the cores I'm looking for in making an original inductor , but without knowing how to identify that core , I'll never know where to start. This makes it somewhat frustrating. Most electrical components have some kind of mark or stamp to that allow for indentification. So far I have no idea what to look for when trying to get the right core for this pultec inductor. If anyone has the info ,  can some clues or dimensions be given here. If I find these cores I could make them available for DIY members here on the forum.

I think I can source the inductor wire from a guitar pickup winder supply house. Just don't know the guage yet. maybe 40 or 44 , not sure. any clues ?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 06, 2008, 09:17:43 PM
No, do a search... Joe said he made that schematic from 3 REAL tube Pultecs.
Like I said, there are probably a couple different revisions.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 07, 2008, 03:46:29 AM
Quote from: "khstudio"
No, do a search... Joe said he made that schematic from 3 REAL tube Pultecs.
Like I said, there are probably a couple different revisions.


EDIT... I just found out they may not be as accurate as I thought, sorry.


In one of the links I posted, Pat gave the size & AL Value of the cores.

AL value = 876
Size = of a Quarter
Wire Gauge = 34 (if your core is close to 876 AL = (876uH - I think... 90% positive)

To find the AL value, you can wrap the cores 100x
it doesn't matter what gauge it is!!!
After wrapping, measure the inductance... this is your AL Value.

A little secret - if you wrap it 10x & you get aprox 12-16uH (I think), your VERY close. :wink:

After you get your AL value... there should plenty of info around that tells how to do the math for the number of turns for each tap.
I know the cores were Black... but I don't have or even remember if there was a # stamped on them.  :oops:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 07, 2008, 06:24:10 AM
Kevin,

Great info, I have not come across this info on finding the right core in most of my readings thu many posts. If and when i find the right core I will try to make these available. But now, I have to go thru the surplus cores to find the right one. wind them measure the inductance and hopefully find what I'm looking for.

I'll keep plugging away at getting the Pultec passive filter section.

I was at 125'th AES in S.F. and talked with a few vendors and there were a few reps who said they might have the passive filter section in schematic form , but I needed to email them. When I get this I'll post it for others to reference. Having this baseline establishes a level of confidence when assembling a EQ like this.  I need to know I'm not building something that was reversed engineered with possible mistakes.
I always check my work when it comes to accuracy , its my way of keeping this DIY thing real and professional.

Is there a primer I can read up on for wrapping round cores so I know I'll get a accurate AL reading when I check inductance measurements you mentioned above ?

One additional note : Often when I tinker around electronics I have found the quarter sized round torrodial cores used as chokes in switching power supplies, are these cores different in composition to the inductor cores needed for a pultec inductor  ?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 10, 2008, 06:45:10 AM
Hey,
Somebody - Needles - I think, sent me a PM about my faceplates.

I took the time to send the info to your EMAIL (link button) & it bounced back. :?
Just letting you know I tried.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: crisotop on October 11, 2008, 07:36:16 AM
Awesome! Beatiful builds - congrats  :thumb:

cheers
christoph
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 13, 2008, 06:35:06 AM
Quote from: "crisotop"
Awesome! Beatiful builds - congrats  :thumb:

cheers
christoph


Thanks for the compliments.

 :green:

I'm loving these EQ's & can't believe what they do to things like Kick drum, Piano, Vocals, Snare, Bass... you name it but so far these are my favorite things.

Passive EQ's... now I know what all the fuss is about.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: EmRR on October 13, 2008, 11:15:56 AM
related:

Audio Cyclopedia regarding toroidal coils, as recommended for EQ construction:

...circular core composed of molybdenum permalloy dust mixed with a plastic binder, compressed into a doughnut under 200 tons-per-square inch. By the use of this type winding, coils with a Q of several hundred are possible. Efficiency is extremely high compared to other designs.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 13, 2008, 08:02:33 PM
Are these the toroid cores needed for a Pultec ?

http://www.cwsbytemark.com/index.php?main_page=index&cPath=206
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 13, 2008, 10:16:56 PM
Quote from: "maxwall"
Are these the toroid cores needed for a Pultec ?

http://www.cwsbytemark.com/index.php?main_page=index&cPath=206


If you can figure out which ones will give you an AL Value close to 876... then I think they'd work well. Maybe you can call them?

I would NOT go any LOWER with the AL Value (because you'd need more turns & with the "876" AL, you'll need about 1300+ Turns for a 150mH Tap.

I wouldn't have a problem (myself) with a "slightly" HIGHER AL Value = Less Turns - BUT - the Resistance for each of your taps may be slightly off which will effect your BANDWIDTH Control (Compared to the Original) but I don't think this would make it sound bad, it's just not going to be EXACTLY like a Pultec. So unless you're trying to make an EXACT Clone, I would not sweat it.

Keep in mind that I wound a Ferrite Core too:
My MAX turns was 200+ :!:
& it doesn't sound bad at all & the resistance per tap is WAY off... so finding the RIGHT Core Material with a "Close" AL value will get you WAY closes than with the Ferrite Cores.

Someone else with more knowledge will have to help you figure out "Which" model to get from that site.

Also... don't be afraid to buy extra's... I'm not sure what their tolerances are, so there MAY be a few duds in an order.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 13, 2008, 10:25:22 PM
kevin,

Do you have the turn stops and dc's for the other taps. This would be
very helpful. I can't recall them listed anywhere.

150mH /DC resistance ? / turns 1300+
82mH / ? / ?
58mH / ? / ?
47mH / ? / ?
33mH / ? / ?

you wound your cores by hand, I see . I cant think of a easy way to wind a toroid other than by hand .  A machine for this type of winding would be cross between a sewing machine and a lathe. Also, I noticed it does'nt require a sophisticated winding pattern to do these like other cores that use interleve patterns  
(CJ where is you ? )


I think this site is a good place to start. These folks will even wind a inductor if you needed one. I'll have to call them and give them the core specs AL DC resistances , wire (awg) size and inductance taps needed. Even better 1-800 number so no time limit on talking to these folks.

The cores look dirt cheap, and a roll of wire for $10 , my kind of place.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: gevermil on October 13, 2008, 11:15:14 PM
sorry guys  , whats the proper hook up of the output transformer ?
150 : 600  or 250 : 600
thanks a bundle
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: drpat on October 14, 2008, 01:52:23 AM
...
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: drpat on October 14, 2008, 01:54:25 AM
...
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 14, 2008, 03:59:55 AM
Quote
Wire Inductance DCR
Blue: 147mH 30.9
Green: 97.9mH 24
Yellow: 84.1mH 21.9
Orange: 50.9mH 16.7
Red: 32.2mH 13

Wound on a toroid core....


EDIT: fixed wire color
_________________
-Patrick


Found Here:
Pultec Inductors again...
http://www.groupdiy.com/index.php?topic=25482
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: nielsk on October 14, 2008, 08:41:17 AM
KH, you wrote that you did not servo the JLM hybrid input.... and I see no coupling caps. Have you measured for DC in the audio path?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 14, 2008, 03:11:50 PM
Quote from: "nielsk"
KH, you wrote that you did not servo the JLM hybrid input.... and I see no coupling caps. Have you measured for DC in the audio path?


No caps & less DC without the servo engaged.

All info about using the Hybrid is HERE:
From page 1 of THIS thread!
Quote
All 3 use the JLM Hybrid circuit for the input buffer - See Topic Here:
PULTEC - Input Options -Buffers- Imp - TX - JLM Hybrid opamp
http://www.groupdiy.com/index.php?topic=26790


I know I probably should have added caps (at least) to the inputs... but I know my studio & I'm aware of what gets plugged INTO them.
If I were building for others, I'd definitely add them.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 14, 2008, 03:50:54 PM
OK,
ALL this info is from Pat. Just to let everyone know, he spent a LOT of time researching, Testing & even buying, winding & trying about 30 different types of cores until he found a FEW of them that worked like his original Pultec.
His goal was to make an EXACT Clone BUT he did say that several of the other inductors sounded good too. PLEASE do not beat up Pat for info... He was kind enough to share all his hard work but will NOT hold anyone's hand thru their builds.
NOTE:
The below calculation is for an EXACT AL value of 876!!!

My inductors were NOT exactly the same AL value, so I had to do the math myself (& use an inductance meter) to wind my cores - using the calculations below... so EACH inductor will need to be calculated because of tolerances & AL.

this is the info he sent me:

Quote
As far as the Pultec inductor goes, here's the secret recipe:

The core that I used is black.
The dimensions are as follows:
Outside diameter:   23mm
Inside Diameter:   14mm
Height:         8mm

AL value of the core is 876µH. Test this by wrapping 100 turns around your core, then measure the inductance.

The wire gauge is #34AWG

Calculated turns are as follows:

32.2mH      606 turns
50.9mH      add 156 extra turns
84.1mH      add 218 extra turns
98mH         add 78 extra turns
147.5mH      add 240 extra turns

Turns formula:
N=100 x SQR(L/AL)

Where:
L= desired inductance in µH
AL= AL value in µH

So, for the 32.2mH tap...
N= 100 x SQR(32200/876)
N= 100 x SQR(36.75799)
N= 100 x 6.06284
N= 606.284 turns


NOTE that the Turns formula & calculation can be found by SEARCHING on the NET!
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 14, 2008, 04:00:51 PM
re-post of what I said earlier:

Quote
Keep in mind that I also wound a Ferrite Core too (for my RED unit):
My MAX turns was 200+ :!:
& it doesn't sound bad at all & the resistance per tap is WAY off... so finding the RIGHT Core Material with a "Close" AL value will get you WAY closer than with the Ferrite Cores I used.


The moral of the story here is, that finding the ORIGINAL Inductor is not easy but using the info Pat shared with us, finding the right core material & a CLOSE AL Value will make a GREAT sounding inductor for a PULTEC or any Passive EQ. I wouldn't sweat finding the exact value BUT I also wouldn't go too much LOWER with the AL... Higher AL means LESS Turns. :wink:

Thank you Pat :!:  :!:  :!:

 :thumb:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: gevermil on October 14, 2008, 08:33:41 PM
Yes , thank you Pat for all the info  :thumb:
kev too :sam:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 15, 2008, 03:29:29 AM
Thanks to Pat and Kevin for continuing this discussion and reducing the explanations and mathmatical material into something meaningful. This is probably one of the best inductor Q&A primer threads for the beginner as well as seasoned core winder I've seen in a while. I'm sure I have more questions , but for now its time to locate the core with the magic AL value.

I located some wire locally with a #33AWG , I was looking for #34AWG
like Kevin suggested , will 1 AWG off make a huge difference ? I'm assuming not , at least not too much in DCR hopefully.

Is there a AWG component to the formula above that tells me DCR for a given AWG size ?

Also, when creating the taps within the core with the colored insulated wire, do you just solder the insulated wire to the core wire and tape it so it wont touch any other points in the core or core wire ? then repeat the technique until all taps are made complete ?

Would the tape serve as a way to secure the tap to the core ? or was beezwax used for this purpose ?

By the way , is there a inductance meter geared for the DIY'er that is fairly accurate as well as affordable. A few have been mentioned in the past but I think those meters are out of production. any suggestions would be helpful as well as experiences. I've seen meters as low as $50 , does this mean beware ?
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: CJ on October 15, 2008, 04:44:16 AM
BK Precision makes an ok hand held meter.

To make a tap, just pull out about 6 inches of wire, the same wire you are winding with, divide it in half, twist it, put some sleeving over it and solder it to a pc board or terminal strip.
then run the pvc to the terminal.

I have solder joints on my inductors, but looking back, they could have sharp edges that can nick the next enameled wire turn.
If it is taped up, you do knot know if pressure is being applied in a bad way by the tape.
this fussy stuff is taken seriously by commercial winders, but for DIY, who cares, as long as it works and the house does not catch fire.

A side note, wire gauge is not an exact science.
Triple insulation will mic out the same as a single build, but it will have twice the dcr, since half the diameter is insulation, and not conductive copper wire.
And Phelps Dodge will be lighter for the same gauge as Essex, so when you order you have to keep that in mind.

You can get old stock wire on evilbay if you really wanna run this down, but it might be more fragile.

this is low voltage audio waves, so you only need a single build wire.

Insulation was not as good back then, so more insulation was needed to get the same voltage rating as the new fancy treatments, so do not go by voltage ratings, todays wire wqill be much higher, but the insl will be the same thickness.

kh, did you fix the clipping, or do you just watch your levels on the hybrid input?

measure an ac sine wave with 10 k, then with 620.
hold the pri V constant, see if there is a voltage drop with the 620 ohm.

only 1 ma flows at 10 k at 10 volts.

the same 10 volt audio drags 16 mils with the 620  ohm, or 16 times the current.

this can make the transformer respond differently.

interesting to note that the maximum flux density does not change with current, only voltage.

so  if you have a 10 k resistor across 10 volts, and a 620 ohm resistor across the same ten volts, the transformer feels the same flux level, even though there is 16 times the current.

think about that for a while.

thats what i am going to do right now so i can fall asleep.
 :cool:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: electrochronic on October 15, 2008, 05:13:42 AM
Can I add CJ to the list of thankyouz

Quote
Dr Pat wrote : 150µF cap is a tant, so the “+” symbol should actually be to the right of the tant instead of the film.


Whoa , 150Uf Tant , thats a big one !!!
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 16, 2008, 02:46:19 AM
CJ,
Good info. :thumb:

Quote
kh, did you fix the clipping, or do you just watch your levels on the hybrid input?


Well, it's not really clipping, I just can't turn the high boost up as high or I do like you said & watch my input levels.

I did some general measurements & it seems that with the original Input TX setup, with the 620 secondary loading, the level drops approx 3-5dB.
So... 2 things happen from this:
1 - you hit the circuit  & Inductor a little harder
2 - the output amp levels have to be turned down to compensate for "Unity Gain" from input to output.

Pat said the original had a slight boost when going thru the unit in bypass... I think 1dB or so.

I set mine up with NO boost.

I tried to add the 620ohm resistor after the HYBRID & NOTHING happened.
Joe said this is right... that the HYBRID is so strong that the 620 does nothing but add distortion & pulls the amp out of class A towards AB.

For those of you who are building a Pultec or Passive EQ:::


There are SO many items that add up to the "Mojo"
I never planed on making mine exact but did want to try to get as close as I could. & I can say without a doubt, that my "BLUE" unit definitely has some "Mojo" that my other units don't!
But , they don't suck & are Killer too, just different, which is why I keep saying the circuit/passive EQ is just cool & you can set it up SOooooooooooo many different ways & STILL have a great piece of gear.

Take it from me... DON"T sweat all the details UNTIL you actually build one :!:  :!:  :!:
It doesn't matter if it's "Just like a Pultec" or not, as long as YOU have a working unit to try out different components & hear the changes yourself.
You will never understand what the different caps, inductor, TX's, etc... will sound like until you try it yourself. :wink:

You'll learn a lot & be able to tune it the way YOU like.

I expected to like my BLUE unit so much more than the others that I'd want to make them ALL the same... I was wrong.
But don't get me wrong... the BLUE units high boost (using the inductors I wound) is my favorite of the high boosts of all three units.

These 3 stereo Pultecs/Passive EQ's are among my absolute favorite pieces of gear I've built... & I've built a LOT of stuff.
I used EVERY channel on the last 3 mixes I did... just Killer!!!
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: CJ on October 16, 2008, 04:03:13 AM
A triple bypass would be great.
No, not heart surgery, although I could probably use some, I mean a rotary switch:

1)  Total Bypass
2)  Line Amp Only
3)  Eq Section and Line Amp


Yes on just build something.

Remember when everybody was hot on the Calrec with the Tants?
Freaked me right out.

I would not have guessed that the order you put the filter components in would affect the sound.

Since this is AC we are dealing with, the signal hits cap first, inductor first.

So would not it be the same?

Manleys has it opposite.
I built mine stock.

Maybe because of the single ended nature of the filter section...
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 16, 2008, 03:53:40 PM
Quote from: "CJ"


I would not have guessed that the order you put the filter components in would affect the sound.

Since this is AC we are dealing with, the signal hits cap first, inductor first.

So would not it be the same?

Manleys has it opposite.
I built mine stock.

Maybe because of the single ended nature of the filter section...


There is a definite difference in the sound when you change the order... I remember posting about it a few times.
Are you referring to my comments about the order or did you try it yourself?

BTW... it's good to see you back CJ.
You seem pretty chill lately.   :cool:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: CJ on October 16, 2008, 04:18:53 PM
Yes I am all better now.

Less BS, which will be more boring, but easier on the forum members.
 :green:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: noulou on October 16, 2008, 04:33:27 PM
Quote from: "khstudio"


Pat said the original had a slight boost when going thru the unit in bypass... I think 1dB or so.



Maybe
this has something to do with the fact that so many people seem to love original pultecs on bypass! According to my experience 1dB louder always sounds better.

Just a thought.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 16, 2008, 04:42:23 PM
Quote from: "noulou"
Quote from: "khstudio"


Pat said the original had a slight boost when going thru the unit in bypass... I think 1dB or so.



Maybe
this has something to do with the fact that so many people seem to love original pultecs on bypass! According to my experience 1dB louder always sounds better.

Just a thought.


Trust me... it's not just the added gain.
You've got several components like a 2520, Tant cap, Large 1uf cap + in & output TX's the signal is passing thru (I'm referring to the SS Pultecs myself) the TUBE version has even more & different components... like Tubes, for one  :razz:
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 16, 2008, 05:21:15 PM
Quote from: "CJ"
Yes I am all better now.

Less BS, which will be more boring, but easier on the forum members.
 :green:


It's all about balance. You can be so damn helpful & one of the smartest people around here. It took me a long time to understand you... so don't change too much... you just don't have to be so mean (like one thread I read.)

I've learned a lot from your posts & appreciate the time you take to share your knowledge.  :thumb:

Hey, when you say the NEW cores are a lot stronger... are talking Ferrite or Iron Powder core?

The Cinemags are much more... ahh, "Linear" sounding - Cleaner, more accurate to me.
But these Iron Powder Core's with 1300 windings have this flavor that is Very Musical & will "Break-up or "drive" when pushed (in a cool way).

Also, Pats Original Pultecs has the Cap BEFORE the inductor.
But a friend of mine let me rip open his TUBE TECH Unit & it had the Inductor 1st.

Both sound cool but different... I really wanted to put a switch on mine but didn't. :sad:  Very easy mod to add.
& for anyone that missed my comment about this:

The Inductor first sounded more "Vintage" & mid-range focused or colored.
& the Cap first was more "Open" sounding & seemed to (maybe) be a little more useful all around... if that makes sense.

BTW... I THINK Pat said that the LANG "May" be  Inductor first... like the Tube-Tech. Have to ask him again to be sure.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: CJ on October 16, 2008, 07:10:12 PM
I still have this, I think Rafa is to thank, maybe Canadia Greg, I forgot:

No wait, IJR, right!
Where the heck is he anyway, working for Hesbola   or something?

http://i37.tinypic.com/25ix0dx.gif

Since we like to split atoms on all our DIY, which is why we are the best in town, which side does the foil lined up in the Pultec caps, I bet Pat wrote it down.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 16, 2008, 10:30:56 PM
CJ... that's cool. :thumb:

I've been trying to get Pat back around here but he's so damn busy... He does live around Arnold so...... "He'll be bock"
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: CJ on October 17, 2008, 01:59:30 AM
Yeah he's putting the finishing touches on that Papa Roach live album.

There was talk about the Torwico being the Pultec core also.

There is a thread around here somewhere about that.
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: khstudio on October 17, 2008, 08:17:57 PM
CJ... I need your help!

Sent you a PM yesterday. Did you get it yet?

Anywho,

I just got a pair of the Sowter 9820 & can't find any info about HOW they should (or shouldn't) be Loaded on the secondary.

Are they meant as a "Drop In" replacement in the API 312?

Meaning - Should the ZOBEL network be set up the same as the original 2622 TX???

I have spoke with a few guys that just use the original Zobel values & No secondary loading but it's never been mentioned ANYWHERE if the Sowter 9820 input TX needs different loading or compensation.

I thought you might be able to help me because (I Think) you helped Brian with these.

Thanks man,
Kevin
Title: My 3 DUAL PULTECs - EQP-1a3 - Solid State
Post by: CJ on October 17, 2008, 08:37:56 PM
You can do a freq plot of the transformer out of circuit, see if it has a bad rise that needs squishing.
Don't bother with the bass, just sweep it from 10K to 100K.

If the Sowter has the same peak,  put it back in the circuit and tweak the zobel values til you get a compromise between lost mid range and no major resonant peaks.

Here is the orig freq plot, out of circuit.
Sweep the Sowter and see if it matches.
If so, then just slap the stock network on there.

I think he tries to get the vintage stuff as close as time and materials permit.
Although sometimes he improves the iron if the original had stuff that could be made better.
(http://vacuumbr.ipower.com//The_Lab/API_2622/freq_1.jpg)