S800 Support Thread

[Holger]

I'm not sure if the stacking method is better than the Matta method building it up from the side panel.
Maybe my method makes maintenance it a little bit easier.
I hope I never have to open the beast again...

 

[kml23956]

I am building the 8 channel version of this.  Does anyone know the current needed for one card?  I see that I need +- 18v but what is the current required?

 

[signalflow]

I am building the 8 channel version of this.  Does anyone know the current needed for one card?  I see that I need +- 18v but what is the current required?

Check the datasheets for the chips used.  I'm pretty sure the 5532 is 10mA but check to be positive not sure about the TL071 same ball park maybe.

make sure to check the correct mfg data it may vary from company to company.

-Casey

 

[sintech]

I am building the 8 channel version of this.  Does anyone know the current needed for one card?  I see that I need +- 18v but what is the current required?

Running eight here no problem, using a 50VA transformer with heatsinks on the regulators. Good luck with your build, it's a beautiful eq.

 

[kml23956]

thanks for the help

 

[kml23956]

OK.  I finally have Tat's eight channel case reworked so I can fit everything in it.  What wire should I use to hook this thing up?  Matta has pointed out that there are almost 400 wiring connections that must be made.  Happy, happy, joy, joy.  So what manufacture of wire do you think would work best?

 

[ewald]

Hi kml,

If you're opting on matta's method of pcb orientation, you'll find that bit of planning will go a long way, as space is severely limited in those cases! Ie measure wire distances from each pcb to destination and use wire no thicker than +/- 2mm in diameter(14awg) as 400 odd wires toghether will become rigid/stiff consequently making it hard to manoeuvre/fit them all inside. 

AND make sure of each connection, with DMM if you must, before closing up-you'll never want to go in there again! - I ,idiot that i am, somehow skipped the nulling proc on one channel and only found out after finishing up : what a joke having to go in there again!(not wished upon my greatest enemy!)

cheers

Ewald

 

[Brolik]

I present to you my first GroupDIY project!  ;D I've made a stompbox or two before, but this is a whole new kettle of fish!!

Probably should've tried something a little easier for my first go, but I'll tell you what I now know how to fly some damn wires now.  Ewald ain't lyin' about not wanting to open it back up, I forgot to put the power led in at first. I almost cried. 

As you've by now noticed I'm missing the sifams on the last two channels, anyone got some spare sets?  I could really use a pair right about now. 

Thanks to everyone who put this project together! I finally have some decent eq's!!  ;D  ;D  ;D

Matt Sommer

 

[ewald]

Congrats matt, feels good, d'n it! Nice move on the styrene's-nothing beats bashing your head at 2 in the moring cus your hpf WON'T work! :'(

 

[kml23956]

Thanks for the replies.

I have ordered my wire and will post pics as soon as it is done.  Can't wait.

Kevin

 

[Dr nEon]

Wow,well done...!..

great pics ,but my browser is having immense difficulty in loading them all..

OK I have a question about unity gain with the S800 , in unbalanced mode.. I have read this entire thread a number of times.

So..yeah we have the trimmer on board , and I've set it for unity , in a balanced situation.

Now..I rig it up in an unbalanced situation..i.e my home studio where it will live , and so I have, our old friend, the 6dB level drop.

I can readjust the trimmer for unity in unbalanced mode, but my question is if this is the best remedy , or should the trimmer be left alone , and some other resistor values be changed?

Only asking , since in other circuits like the calrec eq,input res could be changed , and the vca i/p resistors on the gssl were the best spot.

I cant find anywhere, the official word on the purpose of the trimmer; I'm assuming it's to set balanced unity/CMR...but is it ok ,or a bit crude perhaps , to use it as a 6dB compensation boost ?

any thoughts anyone?

Cheers

nEon.

 

[Dr nEon]

any takers on the above question?

cheers!

nEon.

 

[Harpo]

Hi nEon,
looking at the schematic and leaving the trimmer (shunt in a U-pad) alone, R36 would need to be increased from 15K to 30K and compensation cap C21 decreased from 100pF to 47pF for your required +6dB unbalanced gain. Could be made switchable by paralleling a 2nd 30K and a 2nd 47pF to alter between balanced and unbalanced mode. (IMHO C21 could be kept at 47pF. The NE5532 is unitygain stable and the LPF increase from 106kHz to 225kHz for balanced operation seems safe and far enough outside the audible range to get noticed, i.e -0.034dB vs. -0.134dB tested at 20kHz). Another approach could be to measue the trimmer for the required shunt resistor values for both operation modes. Just my 2ct.
Good luck.

 

[Dr nEon]

Hey Harpo!

Many thanks for your great ideas!

Since I'll probably only use this in an unbalanced setup (for the foreseeable future, or until I get a desk with a balanced patchbay!) , then I would happily just set the trimmer for unity gain in that mode .In the future I could simply open the box up again and readjust the trims when I have a  balanced setup .

However,aligning for unbalanced unity made me worry about hitting the -ve input of U1 too hard , once i measured it  with a +4dBv tone coming in from the desk, and I'm not sure just how much the TL071 can take,on its inputs. Maybe I'm worrying over nothing...please would someone tell me if I am!

If my concerns make sense, then I'd leave the shunt nulled for unity in balanced mode, and go for your elegant solution of boosting the output instead. 

OTOH if I'm worrying (again!) over nothing , then I'll just set and forget the trimmer..for now...

Also, that's a brilliant level switching scheme,Harpo!...thing is ..ironically....I've made other units switchable,ssls etc, to handle unbal insert chain scenarios/when I want a balanced mastering chain , but I think I'm only gonna need to use these s800 eqs over unbal insert points,so I was hoping to keep it simple.

Thanks again and Cheers!

nEon.

 

[Harpo]

my pleasure.
No worries about hitting the TL071 input too hard. Your +4dBV or +6.218dBu is already reduced to max -0.3dBu by the at least -6.5dB U-pad with series resistors R3+R4 and the 10K shunt trimmer/rheostat in cw position, so your 1.585Vrms/2.24Vpk sending device is 0.748Vrms/1.057Vpk max after this pad.
A TL071 has common-mode input voltage range of at least +/-11V and output voltage swing of +/-10V .. +/-13.5V, depending on load. This diff.amp at input stage is set for voltage gain of 10 or +20dB for weak souces, resulting in a gain range from zero to +13.5dB, adjustable by your trimmer.

 

[Dr nEon]

Aha! Ok, so I was worrying about something pretty small, as far as the input voltage range of the tl071 is concerned.

Looking again at the TL071 data sheet , I understood it better ,after reading your explanation Harpo.

So I'll just set the shunt trimmer for unity in unbalanced mode , and start listening instead of worrying!

I've learned something along the way!

Cheers!

nEon.

 

[buschfsu]

are there boards still around for this?

 

[MasonAtom]

Hoping to finally get started on a 2 channel S800 fitting in a 1U rack.

Anyone got a drill pattern for the front panel pots?

Thanks.

Mason

 

[peterc]

Hi all

I am doing another run of these, check this thread

http://www.groupdiy.com/index.php?topic=33831.0

Peter

 

[substitute]

Hoping to finally get started on a 2 channel S800 fitting in a 1U rack.

Anyone got a drill pattern for the front panel pots?

I did my own front panel, I don't really have a layout, I just imported the graphic of tat's cases to illustrator, scaled it to be 19" wide, and used the ruler tool to take measurements then transfered those to my panel.

I'm happy with how it came out but I had to mount the pots off board to make it work.