DIY equalizer based on Studer 169 (standard and mastering)

[envelope]

Hello Audiox,

I love this EQ, and hope to build several more with different frequency's / boost / cut amounts. Although it behaves differently depending on gain/freq. it just takes some getting used to.

Thank You for sharing this design.

 

[joshco]

looks awesome!

 

[conleycd]

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 !

For true bypass unbalanced switching you might want to consider the top PCB board for a clean install.

http://www.muzique.com/pcb.htm

This is intended for guitar pedals etc... but would totally work in this application.  I think they're nice because you can use a slick momentary switch to trigger the switching.

CC

 

[benlindell]

Success!!!

Hey guys, after sitting on the shelf since April. I cracked that scale modification!!! I nailed the High Shelf Steps but the lows were giving me problems, I finally opened it back up tonight and found I had an extra resistor that wasn't needed.

I can't tell you all how happy I am that I finally got this bugger figured out. I now have -6, -3, -1.5, 0, 1.5, 3, 4.5, 6, 9, 12 db steps totally on point!!

I'll follow this up with my revised trace cutting modification in a minute. Also if anyone want I can post the spreadsheet I used to figure out my steps.

I put up sweeps here: http://blog.benlindell.com/?p=294

 

[benlindell]

Here's the trace cutting guide:
Blue are resistors, red is cuts, and green is wire

 

[nickeveslage]

What are you guys doing about C18, 19, 20, and 21?

I've not been able to find any film capacitors in the correct value (22pF) and I don't believe this would be a job for a ceramic capacitor.

Am I a fool?

Thanks

 

[Davo]

the feedback caps... just use ceramics.  If you want "best" quality use COG/NPO's

cheers,
dave

 

[nickeveslage]

Thanks for the ultra fast reply!

I guess I've just had it in my head that, when possible, avoid ceramic caps when it comes to sound.

Thanks again!

 

[benlindell]

Man... So after fighting with this thing for soo long, I can't find any 1U cases that it fits. Par-Metal are too small. Dan's new cases are just a little too small. Any one out there finish these up with a 1U casing that works? I'd like to avoid making these 2U if possible but I'll do it if no solution presents itself soon.

 

[skal1]

hi


do any of you chaps know what Discrete Opamp boards you get with this project .

thanks

skal1

 

[strangeandbouncy]

Yup,



   from Gustav you get Neumann OA10 with the 500 series version. it might be in addition, not freebie. Cant remember. They sound fantastic in this eq. I have one pair with OA10 and one pair with 2520. Both great!



    AndyP

 

[skal1]

thanks andy , did you do the mastering one? because i can not see a place a doa will fit on that board or am i missing something.

cheers

skal1

 

[strangeandbouncy]

Hi Skal1,



  no, I did 2 pairs of the 500 series one, but built them with no mid band, and added switchable frequencies top and bottom. I also hacked the board to use the second DOA as balanced input. I am not balancing the output, just using impedance balancing.


    Kindest regards,


    ANdyP

 

[skal1]

ok  enough sed, so how would i graph a doa on this circuit would it have to be on the front end or the back end.


skal1

 

[strangeandbouncy]

not sure what you mean, graft a DOA onto the mastering version . . .
Sounds ugly to me!

 

 

[bdubya]

If you have the original mastering version pcbs, just use the ne5532/34s that fit the PCB, and be happy, it's a great sounding equalizer stock. 

 

[Matthew Jacobs]

Man... So after fighting with this thing for soo long, I can't find any 1U cases that it fits. Par-Metal are too small. Dan's new cases are just a little too small. Any one out there finish these up with a 1U casing that works? I'd like to avoid making these 2U if possible but I'll do it if no solution presents itself soon.

You could always mount the switches off board and have the PCB flat at the bottom of a 1U case. Keep the runs short.

JD

 

[bobine]

Man... So after fighting with this thing for soo long, I can't find any 1U cases that it fits. Par-Metal are too small. Dan's new cases are just a little too small. Any one out there finish these up with a 1U casing that works? I'd like to avoid making these 2U if possible but I'll do it if no solution presents itself soon.

The 1RU mastering version? For the height, I used washers to lift the top a just a bit on a Par Metal case. Are you using Dan's front panel? It was made wrong. It will work if you flip it over and put the power on the left side, blank side out... (or if you run your controls from HI to Lo ). Or make your own panel. None of it very pretty.

 

[bobine]

I finally solved the problems with the 1RU case and finished this. Thanks to AUDIOX and all who contributed.

I used a Par Metal case, a front panel from Dan, and the 15v PS sold by burdji's DIY General Store in the WM.
The boards are too tall for the case and just a bit too long. The front panel doesn't work the way it was intended.

The photos:
I notched the top and bottom edges of one board to fit over the side lips.

I added a spacer to lift the top to the height of the boards. It fits in the rack okay.

I straped in the PS and clipped the pins. Tight fit! Insulate well.

Front of unit. Power switch is on the left.

Back of unit. Top is not lifted in back.

Works great. Boost/cut range of the mastering version.

Lo freq selections.

 

[MikeClev]

Great stuff Bobine!

Those frequency plots are interesting. I wonder if you could indulge me and test a theory I have. Could you plot one of the low boost frequencies on full boost and see if it changes at all when you change which high frequency band you have selected. I have a hunch that it will change the low band turnover frequency as per this thread: http://www.groupdiy.com/index.php?topic=43089.0 I haven't built the circuit yet and my simulation skills are non existent.

Thankyou in advance!