Studer 169 EQ in API 500 format

[shabtek]

doc neon, i wold not worry too much about noise...
but pop or thump when switching would be a small concern

 

[Dr nEon]

Thanks Shabtek,

Since last week I decided to just breadboard it both ways and see... I loved the idea of just using the selected resistor pair , but in practice it was a little noisy, even keeping connections as short as poss. As soon as I switched to the 'closed' resistor chain, it was really clean, so i've settled on this arrangement.

Thanks for chiming in!

Cheers

nEon.

 

[druu]

Doc, can you elaborate on your closed design? I'm trying to create the same method for high/low pass filters on a design and interested to see how you went. Cheers!

 

[iprovlek]

Hi guys!

My question about this Studer 169 is!Can i use 25k LIN instead 22k LIN pot!

And thanks for any response....

 

[Dr nEon]

Hi druu!

By 'closed' chain, I was just referring to the standard way in which most people replace pots with rotary switches...that is, a chain of resistors around the rotary terminals,with each switch position having it's own cumulative resistance, this representing a particular wiper position on a pot.

It's just the standard thing, pretty well documented around here.

Have a look at the mastering version of the 169..

Cheers

nEon.

 

[iprovlek]

Here is my Studer 169!

Its sound fantastic, i use 5534 instaed DOA but planing to try some....

Im not satisified with front panel and will change the knobs for better looking ones!

I put 6mm omegs and must expand the Audiox hole for pots!

Try 25klin and 22klin and there is no difference!

 

[Indecline]

Here is my Studer 169!

Its sound fantastic, i use 5534 instaed DOA but planing to try some....

Im not satisified with front panel and will change the knobs for better looking ones!

I put 6mm omegs and must expand the Audiox hole for pots!

Try 25klin and 22klin and there is no difference!

Nice job! I used ic's and some Neutrik NTL1's and they sound damn good. For vocal's they're a great tool, just enough functionality to remove the mud and add some presence to SM7's.

 

[iprovlek]

Thanks Indecline!

Yes you right with IC's sound awsome!But im so curious about some DOA's with this EQ!

Planing to put Neutrik's to mine to...

Maybe a stupid question but is there someone who use this EQ for 2 buss?

 

[Sammas]

I don't suppose anyone has an .fpd file for this project that they would like to share?

 

[irfrench]

Hi,

Am thinking about building these (they look like they would be REALLY helpful for tracking) after the glorious summer we've had and am to looking to confirm a couple of things.  I want to build these using the OA10 DOAs and with active balanced I/O.  I really just wanted to confirm a few points - I've looked but cannot see an explicit answer anywhere so my apologies for the dumb questions:

• 1/4w resistors are OK throughout?
• Omit U2 and U3
• Leave jumpers under DOA
• C16 & C17 are for ICs but can be left in (any effect on DOA?)
• C22 and C21 are power filter caps and should be left in

Hopefully that makes sense.  Any help would be very much appreciated.

Thanks, Ian.

 

[Indecline]

Hi,

Am thinking about building these (they look like they would be REALLY helpful for tracking) after the glorious summer we've had and am to looking to confirm a couple of things.  I want to build these using the OA10 DOAs and with active balanced I/O.  I really just wanted to confirm a few points - I've looked but cannot see an explicit answer anywhere so my apologies for the dumb questions:

• 1/4w resistors are OK throughout?
• Omit U2 and U3
• Leave jumpers under DOA
• C16 & C17 are for ICs but can be left in (any effect on DOA?)
• C22 and C21 are power filter caps and should be left in

Hopefully that makes sense.  Any help would be very much appreciated.

Thanks, Ian.

Hey Ian,

1/4W are fine. Omit U2 and U3 for DOA's and jumpers under DOA's should be installed. C16 & 17 are the compensation caps for the two IC's, leave them out for DOA's, they connect to nothing other than the IC. C22 and C23 I believe are for power filtering (noise filtering?), leave those in.

 

[irfrench]

That's great - thanks. 

I'll probably install the compensation caps so I can test the EQ with ICs to make sure it works, and then swap ICs for DOAs as/when they get built.


Ian

 

[taliska]

Going to build a pair of these soon, and was wondering...

Which variant does everyone prefer, with or without transformer? (Neutrik NTL1)

<edit>

Been doing some reading. As far as I can tell, the transformer is mainly useful if you're working with unbalanced i/o. They (the NTL1s) don't seem to be particularly "colourful" from the various reviews I read about them, and the only thing that jumps out at me when I look at the spec sheet is the change in impedance as the winding ratio is just 1:1 and they don't seem to distort much either (1% if memory serves).

I'm new to this stuff so might be way off base here, but I'm going to go out of a limb here and say that judging by the spec sheet they don't look like they do an awful lot to the sound.

Has anyone built both versions of the build? Which sounded better to you?

</edit>

Cheers,

Kaz

 

[Indecline]

The Neutrik's give the signal a little color but it's still pretty transparent. I basically chose between DOA's and the xfr for color, and went with the transformer. Maybe I'll swap the opamps but I'm happy with just the Neutriks for now.

I have noticed on mine the mid parametric is touchy with the gain. I barely cut and the scoop is pretty pronounced (it's also pretty narrow). I'm looking in trying to adust the q and max/min gain but it's not a simple 'swap this' type of mod. Could make them more versitile but I'm pretty happy with them as is.

 

[taliska]

Thanks for the info indecline. I've decided to go for the +transformer option too, as I figured more is always better! 

I've got some of the OA10 boards too, but am going with the ICs initially. I am planning on building those OA10s sometime, but getting hold of the various transistors is tricky if you don't want your wallet to have a heart attack (relative to non-obsolete, better spec'd transistors). I can't remember which substitutions I've settled on off the top of my head, but at best it means my DOAs will only ever be mutant OA10s...but I like the idea of experimenting with them anyway, you know, just for kicks!

Oh, and those holes on the OA10 boards for the pins are HUGE...

<edit>

Ignore what I said about the transistors being expensive. I must have been smoking something/looking in the wrong places. Just checked ebay and they seem to be both cheap and plentiful. Hope they're decent as I've ordered 80 bc212bs and 40 bc182bs...worth a punt anyway for the cost   (everything else I'll get through mouser)

</edit>

 

[Indecline]

You can always post spare transistors on the Black Market. I'm sure you'd sell a few to people with OA10 boards. If I still had my boards I would buy some!

There are a few solutions to the oversized pin holes in the OA10 thread. Some clever people soldered socks on the DOA and eq board, then made the connection with pins.

 

[iprovlek]

Please help guys!

I built 5 Neumann OA10 , use ITT bc212b ,ITT 182b and bc337, bc327  transistors are fliped of, on a my PCB,and none one PCB dont work!

So Im confused...

I dont know what to do!

I made this OA10 here in my country PCB company with all gerbers and files...with all schematics which Audiox gave here on forum...

 

[taliska]

Just wanted to come back to this thread after firing up my first channel and playing with it for a few minutes...

(had to wait on parts, so that's why there has been a bit of a delay getting it going)

Anyway, I built the IC + transformer option, and I have to say that it IS nice as reported by many others!

Obviously it's hard to know the worth of something you haven't heard or built before, and as a newbie, I just had to give it a go and live with the (good or bad) results. For me it was pretty much immediately clear that these are going to be nice additions to my tracking chain.

Anyway, highly recommend this build. Now I've just got to decide on how to finish off the hardware and have a think about whether the hi/lo shelf frequency toggles are worth it or whether it's better to keep the units nice and simple...

Oh, and for those of you who don't check-out the links at the bottom of people's posts, I also highly recommend visiting irfrench's blog. He's got details of his Studer build there, and it's not only informative, but good looking too!

Thanks to audiox for doing a great job with these.

Kaz

 

[irfrench]

:-[ :-[ :-[

Awww shucks!  You're too kind.  Although now I know someone is actually reading that I'll have to be more careful with what I say!

Glamour shot:

Shame I can't seem to get my OA-10 DOA to not set fire to itself!?!  The 10ohm R8 resistor is the poor soul.  If anyone has built this EQ using the OA-10s - can they confirm the wattage they used for R8 please?

Pretty please?

Oh and as for the switch-able High and Low shelf frequencies?  In my initial listens the Low is definitely worth having options for (although the upper selection is more useful for cutting), the High selection is a little more subtle so may well not be worth the tiny-hassle it was to add it.  All in all though I'd say if I were to build another couple of channels I'd still add the switching.

These EQ's are really nice though. So thanks to all - esp. Audiox and Gustav - for making these so accessible.

Ian.

 

[irfrench]

Hi all,

I can't remember having seen freq. sweeps for these EQs here - and I wanted to work out how to do it on PC (not MAC) - so it seemed like a good idea.

This includes the switch-able additional LF and HF shelf frequencies with lowest/middle/highest freq. select for the mid-band section.

Enjoy?  ;D

At least it explains why I heard the HF shelf differences as being quite subtle! 


Ian,
8)