DIY equalizer based on Studer 169 (standard and mastering)

[strangeandbouncy]

HI,

  just gotta share. Some eq we use for it's flavour - NeveyNeve for instance. SOme are tight - da Pultec for instance. Some are just darn flexible, smeary and with a signature - SSL 4000 etc etc etc. Some are just plain different. I am a big fan or Peter's LA-Z, My Helioses, API's, Pye's etc, and wouldn't dream of leaving home without them.

 
    HOWEVER . . . .


  This is just transparent. Plain and simple. I dunno how else to describe it. I think that you could possibly change the signature with different DOA's, but it''ll still be transparent!



        ANdyP


   

 

[audiox]

I am getting a 6dB loss, and cannot for the life of me see why. I am connecting cold to shield in and out.

Still don't know why I am down 6dB. It doesn't seem to be a bal/unbal issue.

Most likely your output is balanced with a simple inverting op-amp stage. With that kind of circuit you get "0dB" between hot and cold but "-6dB" between hot and ground (or cold and ground).

 

[strangeandbouncy]

Hi Audiox,


  Thank you so much for this! There is no balancing simple inverting op-amp stage, just one 2520 as DOA 1. only 1 op-amp in total! I am now using 2503 (actually a profile 4808(?)) as 6dB make-up and balancing. I have no suitable input transformer to hand, so it is possible that there is something there, but surely, pin 3 tie to pin 1, and pin 2 hot should surely be fine(?).


    yet again, thank you!


    ANdyP

 

[audiox]

There is no balancing simple inverting op-amp stage, just one 2520 as DOA 1. only 1 op-amp in total!

Not in the 169 but inside the device that is driving the unbalanced input of the 169.

 

[strangeandbouncy]

Digidesign 196 . . . . happily drives my Helios eq's, Pye channels, etc, all un-balanced . . . .

 

[strangeandbouncy]

Hmmmm, . . . .I did try NOT shorting pin 3 to ground, didn't I? Hmm, now I'm not so sure! I'll have another stab in the morning, and report back to moonbase.


  Hmmmmm.


    Kindest regards,


      ANdyP

 

[strangeandbouncy]

Ok,


    I have checked and double checked. I am not shorting out 1 leg coming in. Even if I connect a transformer balanced output across pins 1 and 2 of the input, I am still losing 6dB!!!! On the face of it, it MUST be a balancing issue, but I'll be damned if I can find it! To make it worse, I have an API 553 EQ which is also unbalanced in/2503 output. It does NOT lose 6dB in the same slot, same wiring. AAAagh! Good news is that I do have a working eq. Bad news is I don't know when I am gonna be able to sort this out! Hectic busy mixing, and i NEED this eq now. FOrtunately, it is amazing with the 2503 makin' up the difference. I'll wait for my Carnhill 10k:10k to arrive before bothering any of yous with this any further . . .


    Kindest regards,


        ANdyP

 

[strangeandbouncy]

Oh Blimey!


  just when I thought I could relax a little . . . Just inserted it pre my desk instead of as an insert in "tools, and it's got 6dB of GAIN now, where it was unity as i/o. Must be a balancing issue. B@llocks.


    B@llocks and Help, actually! I cannot see how it is possible NOT to short one leg, and connect cold to ground. It doesn't matter whether I do it externally or internally to the Lunchbox. I am obviously missing a point somewhere. I have even strutinised the Schemo for a 553 which is also unbalanced in, tranny balanced out.


    I am feeling rather sheepish right now . . . !


        Baaaaaaaah,


        ANdyP

 

[pristak]

Is this a good first eq project?  I've built several Synth modules and a mic pre.

Or would the Neuman W492 be easier?

 

[bdubya]

It's pretty easy.  the only wiring that you need is In, Out, and Voltage.  Go for it! 

 

[nickeveslage]

Hey guys,

Just to be sure (as I'm new to all this stuff), the switches I want are the CK1060 and the CK1059. That is, assuming I wanted to go with the silver contacts and blah blah blah...

Those would be correct switches to use though?

Thanks in advance, and sorry for the rookie question! :

 

[audiox]

Just to be sure (as I'm new to all this stuff), the switches I want are the CK1060 and the CK1059.

I think your order codes are correct (for pcb mount / metric / shorting 1x12 and 2x6).

That is, assuming I wanted to go with the silver contacts and blah blah blah...

Silver contacts work fine because they get cleaned when the switch is rotated.

 

[nickeveslage]

Cool, thanks! Just out of curiosity (and double-checkery) what are some of you guys using for the switches?

 

[Silvas]

Hello.

I´m wanting to do a version using pots instead rotaries for the gains. 5K lin for the highs and 22k lin for the lows. Is this correct ? can someone confirm ?

Also, which will the best way to implement an "EQ bypass" switch here ? any ideas? 

Thanks so much !

 

[audiox]

I´m wanting to do a version using pots instead rotaries for the gains.

Such a project already exists:

http://www.groupdiy.com/index.php?topic=36522.0

Also, which will the best way to implement an "EQ bypass" switch here ? any ideas? 

Bypass is included in the 500 version of the Studer 169 EQ.

 

[Silvas]

I´m wanting to do a version using pots instead rotaries for the gains.

Such a project already exists:

http://www.groupdiy.com/index.php?topic=36522.0

Also, which will the best way to implement an "EQ bypass" switch here ? any ideas?  

Bypass is included in the 500 version of the Studer 169 EQ.

Wow ! I missed that one !

What i want is to put this eq after the so called "$5 preamp" with INA217 and hear how the combination turns out...i´m working on a proto layout.


Thanks !

 

[joshco]

Hello.

I´m wanting to do a version using pots instead rotaries for the gains. 5K lin for the highs and 22k lin for the lows. Is this correct ? can someone confirm ?

Also, which will the best way to implement an "EQ bypass" switch here ? any ideas? 

Thanks so much !

I have 20 K Pots successfully used in my Version. Bypass is also described in this Thread, anyway.
Input to outer Lug
Output middle Lug
Eq input on other outer Lug

hope this helps...

 

[Silvas]

I´m looking for the best way to implement the bypass, since i´ll be using the unbalanced EQ input but i´m leaving the output balancer...maybe there´s an "electric" way of bypassing the EQ, instead a "mechanical" one (switch or relay connecting input to output) ?

For now, the idea is putting a switch or relay to do the bypass and connect the unbalanced signal so it is routed just before the balancer, not sure how to do it the best way.

 

[joshco]

Relay based bypass is a solution or double switches and dual deck rotary switches. I think some schematics are around for relays. The sidechain board for the GSSL is balanced and has a relaybased bypass, if I'm not mistaken...

 

[Silvas]

My idea is to bypass the EQ, which is unbal in/bal out, and is located after the pre, which is unbal out, so, for now, i think i'm doing it with relays. Don't want switches, to keep things neat. That's 3 relays, one for polarity (located at the bal. output), one for selecting the EQ in (from pre / from dedicated unbal eq in), and another for the eq bypass. It's just an idea i have ATM, but i'm cooking a proto in the future and hear...Thanks guys !