How to connect the Turbo board + 2x Super SC (drawing, post #15) **revised

Hi, I'm a new DIYer wanting to start out with the GSSL.

I have little to no experience within this (except really basic stuff like fixing loose solderings, loose contacts, etc, so I'm not completely unknown to the inside of things), but I'm very keen to learn. I have tried to search the forum for answers to my questions, but I can't seem to find them. There's also a slight problem for me that there is such a wealth of information here, that it's hard to sort through it all. I was unsure of whether to post this in the SSL help thread, or as a thread of its own, so please excuse me if I misunderstood something there.


In the parts list it says: 1pcs TL072 DUAL BIFET OPAMP - DIL-8 housing.

So, I enter a big european electronics supplier, called ELFA, and the Norwegian section. I do a search for the TL072, and up comes this:

TL072CP dual JFET-op DIL8
TL072IN dual JFET op-amp DIL8

and a couple of others, but these are not DIL8.
Now firstly, these say JFET, while the parts list says it should be BIFET. Is JFET and BIFET the same?

also, as far as I can see the only difference between the -CP and -IN variant is their working temperature, so I'm assuming it's fine to go with the cheaper one, which says from 0 - 70 degree celcius.. That is, if JFET is ok.

It's the same with the next opamp,
1pcs TL074 QUAD BIFET OPAMP - DIL-14 housing , in the ELFA list it comes up as JFET..

Now on to my second question. I should state that I'm afraid I just haven't read enough about it yet, but right now I'm a bit confused as to what I should implement and it would be great with some pointers.

As I understand it, the Turbo-mode is an option to doing a "double board" version of the GSSL, with almost the same result..? I would like to have the turbo board atleast. But..
Is there then a good idea to also include a sidechain filter? I've read about a stepped version where you choose the cutoff frequency..

Are the turbo and "Regular" sidechain variations on the same thing? Could the turbo mod be another "step" on the hihpass sidechain selector? Or should the Turbo mode be a switch you engage, and the HP sidechain filter an additional rotary selector?

EDIT: After reading a bit more closely on the turbo board thread I found that

[...] there is a complete set of illustrated instructions covering installation in basic GSSLs, as well as units which have sidechain rolloff boards fitted."

Click to expand...

So I guess it could be a pushbutton switch in addition to a rolloff rotary..

I don't even know if that's a possible option, but I will try and read and understand more Just figured I might as well include the question in this post.

Can't wait to get started, and please correct me if I'm posting in the wrong area or whatever.  


Best,
Alex

As long as the opamps are not surface mount (SIL housing) you're ok.

I've always felt like having the turbo and the sidechain filter is overkill.  In it's standard form, the gssl sums the L/R signals into the sidechain, so in laymans terms since you're summing the two sides, anything weighty that's center panned is essentially "overrepresented" in the sidechain and can create compression artifacts on hard-panned instruments.  There's two ways around this: 1. add a 2nd sidechain so each side of the stereo image is compressed independantly (turbo mode), or 2. add a filter to remove low frequencies from the sidechain so that they don't create compression artifacts.  Having them both is like taking aspirin and acetaminophen for a headache - you really only need to take one. 
Although you could make the turbo switchable, and then choose between the two, and decide which one best suits the application you're using it for. 
Here's another very important thing - make sure you make the necessary resistor changes to calibrate the unit for the VCA's that you're using.  Check out these two pages:
http://diy.fischerworks.com/gssl_vca.shtml
http://homepage.mac.com/marten.thielges/gssl/calibration.html

fi you decide to go the sidechain+turbo way, you need 2 sidechain boards.

I've got a turbo version and pretty happy with it!

diyfanatic said:

fi you decide to go the sidechain+turbo way, you need 2 sidechain boards.

I've got a turbo version and pretty happy with it!

Click to expand...

So I could theoretically get, say, the turbosidechain (I've already ordered the kit), and Gustavs Super Sidechain, and have a knob that goes from "Off" through the different filter values and up to EXT.? Do I need anything ELSE than the turboboard and the sidechain board, with their respective components? (btw, where can I find a parts list for the supersidechain board?) And by "you need 2 sidechain boards" you mean for example the turbo board and Gustavs Super Sidechain, nothing more, no?

Thanks for your input!

regularjohn said:

As long as the opamps are not surface mount (SIL housing) you're ok.

I've always felt like having the turbo and the sidechain filter is overkill.  In it's standard form, the gssl sums the L/R signals into the sidechain, so in laymans terms since you're summing the two sides, anything weighty that's center panned is essentially "overrepresented" in the sidechain and can create compression artifacts on hard-panned instruments.  There's two ways around this: 1. add a 2nd sidechain so each side of the stereo image is compressed independantly (turbo mode), or 2. add a filter to remove low frequencies from the sidechain so that they don't create compression artifacts.  Having them both is like taking aspirin and acetaminophen for a headache - you really only need to take one.  
Although you could make the turbo switchable, and then choose between the two, and decide which one best suits the application you're using it for.  
Here's another very important thing - make sure you make the necessary resistor changes to calibrate the unit for the VCA's that you're using.  Check out these two pages:
http://diy.fischerworks.com/gssl_vca.shtml
http://homepage.mac.com/marten.thielges/gssl/calibration.html

Click to expand...

I can see what you mean by overkill ;D. I'd like to try out the turbo, that's for sure. However, it would be nice to have an external sidehcain option though, and then I might aswell include the full highpass sidechain I guess?

Thank your very much for the links. I will definitely pay attention to that..! I'm soon ready to order, I have assembled my own sort of "BOM", though I had to use several distributors. ELFA, Farnell and Mouser.. I first started out with RS, only to find out you had to order like 250 pieces of each...  

i think he meant you'll need a turbo board and TWO super sidechain boards.

Ah.. Is that because I'm basically creating TWO dual-sidechains? Where, if I were only to use the supersidechain, would only need -one- supersidechain board? Just trying to understand..

Yes, in "turbo"-mode you have two sidechains.
If you want to  add a hipass filter (=supersidechain) in "turbo"-mode you'll need  
two (supersidechain-)boards.

In GSSL-mode you'll need just one (supersidechain-)board.

The "turbo"-board is a copy of the sidechain on the GSSL-board.
Adding the "turbo"-board makes the GSSL behave as the original SSL mixbus compressor.

The "supersidechain"-board is just a filter (to simplify it) that is inserted before the sidechain
affecting the sensitivity for different frequencies.

Hope this helps...

Hilsen,

Anders

I've gotten the GSSL board, two sidechain boards and one turbo board now, and soon I'll order the components

I have been thinking about this sidechain thing, and I'm wondering if I am getting this correct now?



Does this mean the super sidechain board can handle both L+R if you need that (GSSL + 1x super sidechain), or if you use 2 super sidechain boards together with a turbo sidechain you just send L to one supersidechain, and R to the other supersidechain? (GSSL + Turbo + Super)

So, GSSL + Super SC, vs GSSL + Turbo SC are two different ways of solving potential compression artifacts from the normal GSSL summed SC? Where one is an optional filter to remove low freqs, and the other separates the sidechains so that heavy bass material in one channel won't affect the other channel?

Sheesh

flipside said:

Does this mean the super sidechain board can handle both L+R if you need that (GSSL + 1x super sidechain), or if you use 2 super sidechain boards together with a turbo sidechain you just send L to one supersidechain, and R to the other supersidechain? (GSSL + Turbo + Super)

Click to expand...

You'll send L to one SSC board, R to the other.  One of those will then go to a turbo board, the other to the GSSL sidechain.

flipside said:

So, GSSL + Super SC, vs GSSL + Turbo SC are two different ways of solving potential compression artifacts from the normal GSSL summed SC? Where one is an optional filter to remove low freqs, and the other separates the sidechains so that heavy bass material in one channel won't affect the other channel?

Click to expand...

You've got it!

Cool! Thanks!

Now, I'm trying to figure out how to wire this all up in theory before I actually do it.. It helps me out to visualize it first, so I've started another drawing:


Am I correct in that this way both SSC filters are active regardless of the turbo switch position, and then the summing takes place after those? Would that cause a problem?

I studied the PDF from Expat, and tried to understand how to hook it all up with two SSC boards and all, but I'm not quite sure if I got it right. Oh and nevermind that the connections to the control board are reversed, just a result of me moving things about

The way I'd like to try and set it up is like this:

When turbo mode is switched off, I only have one sidechain, with one super sidechain filter. So, if the filter rotary is set to OFF, then I have the regular GSSL compressor. Once I activate turbo, I get two sidechains, and also two super sidechain filters. I guess the filter rotary will be hooked up to both ssc boards permanently, but when in normal mode only one ssc board is active.

Questions:

1. Have I drawn it up correctly? (nevermind the missing connections, for now I'm wondering if the signal passes to the correct places).
2. Can I still use a 1pole 8switch rotary? I was thinking since I'm controlling two ssc boards, I'd need two decks? Or..
3. can I just wire the cables from each ssc board to the same pins on the filter rotary..? It says in the turbosidechain manual that:

Also, a dual-gang switch should be used, so that the rolloff selector switch now controls BOTH channels simultaneously.

Click to expand...

I'm still not sure what kind of switch to use..

Trying to wrap my head around it, and I'm slowly beginning to understand this thing, but I still have a long way to go..

Best,
Alex

Also, I can't seem to figure this out, from the expat documentation:




Alex

I'm about to do almost the same.
But I don't really see the use for the Turbo ON-OFF switch. When It's OFF only the left channel goes through the GSSL side chain. So only the dynamics of the left channel or detected. Or am I wrong?

I wired the output of the right-SC board directly in the Turbo board.
For the rest my drawing looks the same.

some more info I gathered:
You will need a 2 deck rotary switch.
Change the input resistor on the SC boards from 20k to 10k
You only need the relay-part of 1 of the 2 SSC-boards.

something is wrong on your draw, the switch need to be bewteen the twwo super sidechain

check it is from an another thread

Thanks for your reply, and yeah I've seen that drawing, but it didn't make much sense to me.. Although, it makes slightly more sense now that I've made my own drawing. I'll see if I can understand it better now. The one thing I especially don't understand is the dotted line with the 47K resistor and the text "Turbo R with only 1 sidechainfilterboard" Does that only apply if you only have 1 super sidechain?

Alex

gyraf use one internal sidechain and turbo is for double sidechain.

if you put one super sidechain with gyraf + turbo is crazy but if someone want make it like that...

if you use turbo and gyraf + 2 super sidechain, eahc super sidechain need to be connected with ointernal sideachain( one with gyraf pcb one with turbo

when it 's on gyaf the left and right channel are working with one SSC

when it's on turbo each left work with the fisrt super sidechain and richt with the second SSC

Aaahhh I think I got it now.. How about this?



Do I have to make any resistor changes on either of the SSC boards now? 2x 10R instead of 2x 20R on SSC1 (the top one)?


Alex

your draw is right, now you don't need to change the 20k, the 20k need to be change if you join the left and right toghether on the first
SSC

but you can do the same thing with just one spdt .
for example the left stay on the first ssc and the right change to the switch bewteen the first and the second ssc.

Wohoo! Thanks! All right, I'll see if I can figure it out with one spdt as well

Guess I can order components and start actually building this thing then! Through another sidechain thread here I also found a 2-deck 12 pos switch as well!
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=451-1013-ND

Alex

Hey guys, couple quick questions

For this setup, do you tie the COM-OFF-ON pads together in parallel to the control board?

Also, same question for the IN SW? Parallel to the switch? (i am guessing i only have to use one of the SSC boards for this...?)

Finally, looking at the above pic, do i leave the 'R' pad on SSC 1 unconnected?

Just making sure thanks for the patience/help!