matthias

mastering pultec eq - gain makeup??
« on: October 03, 2004, 04:00:01 PM »
hello,

I'm planning to build a pultec type eq for mastering purpose...
low cut , low boost and two hi boost stages in series
everything with stepped attenuators and
bigger and more detailed frequency ranges...

i want to build that all in a 2unit enclosure but without a gain makeup...

then I have an unbalanced input and output...


can I just use a G9 or another mic preamp for gain makeup ??
so I can choose, if I want tubes or transistors...

do I need transformers in the passive unit and care for the impedance??


mat


mastering pultec eq - gain makeup??
« Reply #1 on: October 03, 2004, 04:25:23 PM »
You might want to buffer the input stage with either a trafo or opamp circuit to help your EQ get along with whatever preceeds it in your mastering chain. A good clean opamp buffer would probably be best, in case the tranny 'sound' isn't desireable. You can use a mic amp for makeup, certainly... also gives you the ability to add variable signal coloration if so desired, depending on the preamp you choose.
--
J.P. Sheganoski
Recording/Mixing Engineer
www.RisusProductions.com
www.Purevolume.com/risusproductions

matthias

mastering pultec eq - gain makeup??
« Reply #2 on: October 03, 2004, 05:49:02 PM »
do I really need to buffer the input stage ??

in jakobs pultec eq the transformer balanced input is optional...

mastering pultec eq - gain makeup??
« Reply #3 on: October 03, 2004, 07:33:55 PM »
i'd do it just to be safe, so your filter sections responds as expected all the time. it may not be absolutely necessary, maybe someone else could give a better answer...
--
J.P. Sheganoski
Recording/Mixing Engineer
www.RisusProductions.com
www.Purevolume.com/risusproductions

evil grill

mastering pultec eq - gain makeup??
« Reply #4 on: October 03, 2004, 09:05:12 PM »
you can build a bypass to the input buffer for sound comparison

NewYorkDave

mastering pultec eq - gain makeup??
« Reply #5 on: October 04, 2004, 09:46:24 AM »
A transformer is not a buffer.

CJ

mastering pultec eq - gain makeup??
« Reply #6 on: October 04, 2004, 09:08:34 PM »
Well, a Pultec type is based on a 600 ohm filters, so depending on what your makeup gain amp is going to be, you have to match the 600 to whatever, which means a stepup x-former if hitting the grid of a ax7a.
I think a mic pre would be overkill, as you are already at line level. Mic pre's are optimized for a low level input.
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

Flatpicker

mastering pultec eq - gain makeup??
« Reply #7 on: October 04, 2004, 09:59:13 PM »
Quote from: "cjenrick"
I think a mic pre would be overkill, as you are already at line level. Mic pre's are optimized for a low level input.
I wonder what a good solid state candidate would be? Can't remember who it was, but someone posted that they had great results with a 5532.

CJ

mastering pultec eq - gain makeup??
« Reply #8 on: October 04, 2004, 10:22:10 PM »
Don't forget the API/Melcor solution. You could trim the gain resistor to exactly match the makeup needed.
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

electronaut

mastering pultec eq - gain makeup??
« Reply #9 on: October 05, 2004, 01:21:13 AM »
Quote from: "cjenrick"
I think a mic pre would be overkill, as you are already at line level. Mic pre's are optimized for a low level input.


But aren't we no longer at line level once we've made it through the filters?  I thought the filters ate 40 dB or so.

-E.


mastering pultec eq - gain makeup??
« Reply #10 on: October 05, 2004, 01:53:25 AM »
pad the mic pre input -20db, and be careful with the gain. A preamp with seperate gain and output level controls can lend itself to some subtle tonal coloration, i often throw my Phoenix DRS2 on the mix bus outputs for a touch of sweetening. It's a cool way to use different colors for different sounds if you have a variety to choose from.
--
J.P. Sheganoski
Recording/Mixing Engineer
www.RisusProductions.com
www.Purevolume.com/risusproductions

Flatpicker

mastering pultec eq - gain makeup??
« Reply #11 on: October 05, 2004, 12:15:16 PM »
Quote from: "cjenrick"
Don't forget the API/Melcor solution. You could trim the gain resistor to exactly match the makeup needed.
I was hoping you'd suggest that. Seemed like a good idea to me, but I'm always looking for some assurance.  :wink:

matthias

mastering pultec eq - gain makeup??
« Reply #12 on: October 05, 2004, 02:13:34 PM »
@ cjenrick:  so I need 600ohm input impedance that the passive filters work as they should ??

so for my approach I need an input stage ?? transformer or op-amp based??


 

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