SSL 552 Summing Box

[helterbelter]

Neil,

Wow, that must have been quite a few hours of soldering when see the amount of wiring. Tidy !

And....... I see you have a bit of space left to add the GSSL sidechains ! 



Udo,
yes... Can't wait to see the endresult ! Especially with the 501's and 502's in front.  ;D
That'll be more something for the minimixer thread though... I guess.

Well.... My minimixer will be completed soon too..... I hope. Still a lot of mods to do to get it finished. Some custom boards. Most ofthe Special stuff is ready though.... I can't wait to show it, hahaha !


Oh, I forgot to mention : The summingbox that I just finished is built for fun. I had a bunch of spare modules that I won't use myself, so I thought of putting them for sale on Ebay. But then I thought "It would be fun to build something nice out of it". So, I did.
Next week my brother in law will start using it in his studio, for a period of 2 to 3 months.  This way it'll be thoroughly tested. After that I'll put it for sale on ebay.

 

[kante1603]

Udo,
yes... Can't wait to see the endresult ! Especially with the 501's and 502's in front.  ;D
That'll be more something for the minimixer thread though... I guess.

But I will not use them as to form a mixer,at first as frontends for recording,maybe for mixdown later.The summ-thingy will definetely eat the analogue outputs of my firefaces (in the highest possible resolution which is 24Bit/96KHz for my ProTools10):One unit is running directly via Firewire800 as a master,the second is hooked up twice via ADAT to the first units i/os for SMUX in standalone-mode.Summing analog then will give me way more soundwise than mixing ITB.So NO!!!-It´s about summing here

Oh, I forgot to mention : The summingbox that I just finished is built for fun. I had a bunch of spare modules that I won't use myself, so I thought of putting them for sale on Ebay. But then I thought "It would be fun to build something nice out of it". So, I did.
Next week my brother in law will start using it in his studio, for a period of 2 to 3 months.  This way it'll be thoroughly tested. After that I'll put it for sale on ebay.

No you won´t because he´ll not give it back to you-in case of doubt you can ask me for further modules,hahahahaha ;D

And I like the idea you´re talking about making GSSLs from IMO-Modules (having 8 of them).

Cheers,have a good night,

Udo

 

[DigitalMetal]

You need a Krone punch down too like this:
http://www.canford.co.uk/Products/46-201_KRONE-Inserter-tool-2A
Udo,

Krone blocks are very common in broadcast and are very often the way incoming/outgoing sources are terminated and distributed in a studio because they can be very easily re patched.

The tool inserts the jumper wire, punctures the insulation to make contact with the block and trims off the excess wire on each punch down.

The black blocks (what i used) are a common rail buss bar with all contacts common to each other, used mainly as earth/ground blocks.

The white blocks have contacts insulated from each other so that you can attach 10 circuits to each block for patching so be aware of which ones you are buying if you get some.

You have to use solid core jumper wire too like this:
http://www.canford.co.uk/Browse/20383
stranded wire does not work.

 

[DigitalMetal]

Neil,

Wow, that must have been quite a few hours of soldering when see the amount of wiring. Tidy !

And....... I see you have a bit of space left to add the GSSL sidechains ! 

It didnt take as long as i thought it would, i think i could make my second one much quicker

Do you mean to just add a sidechain to the main out of the Mixer or add a SSL bus comp to the mixer?, id certainly like to do that as i had planned to build a GSSL anyway when ive finished the main bigger mixer.

 

[kante1603]

You need a Krone punch down too like this:
http://www.canford.co.uk/Products/46-201_KRONE-Inserter-tool-2A
Udo,

Krone blocks are very common in broadcast and are very often the way incoming/outgoing sources are terminated and distributed in a studio because they can be very easily re patched.

The tool inserts the jumper wire, punctures the insulation to make contact with the block and trims off the excess wire on each punch down.

The black blocks (what i used) are a common rail buss bar with all contacts common to each other, used mainly as earth/ground blocks.

The white blocks have contacts insulated from each other so that you can attach 10 circuits to each block for patching so be aware of which ones you are buying if you get some.

You have to use solid core jumper wire too like this:
http://www.canford.co.uk/Browse/20383
stranded wire does not work.

Good morning(?) Neil,

don´t know where you´re located so I thought it might be good to use the questionmark.......

Thanks for the info!
Yes,that could be a way to go since my prewired stuff (pics some posts ago) is completely made of solid core wires.
Will investigate a bit at canford over the weekend (if I have one :-\).

"Many ways lead you to rome",no?,

Cheers,

Udo

 

[kante1603]

@Paul,

hi,did I get it right that you´ve cut the buscard-pcbs to single pieces an d you use the original guiderails-COOL

Udo.

 

[helterbelter]

Udo,

Yes, I used the SSL guiderails. The buscards aren´t the ones used in SSL consoles. They´re made by Recycled Audio for lunchbox purposes, and they´re originally for 2x 501/505 and 2x502/510/520/522/542. I have cut them up a few years ago..... If I hadn´t, it would have saved me a lot of soldering of the powerlines. But I had to solder extra lines for the 521 anyway. so....

Neil,
yes, I´m talking about GSSL sidechains to drive the VCAs of the 552. This means that you will end up with a superbly sounding G/SSL compressor, with 100%  SSL audiosignalflow. And a summingstage of course !

greetings,

Paul

 

[kante1603]

Hi guys,

have been digging in my big full-of-modules-boxes and took an SL552 with me to my home to check if it´s working right.

If have some questions:

@Neil:You wrote you made an insert point doing it "pre fader"-I bet you meant "Pre-VCA"?I think the pot is the dc-control to the vca(s),therefore not running any audio.I guess it´s a typing error,no?

@Paul:I went trough this thread after a long time.Looking at the pics on the first side I´ve seen no connections to pins 14a+c,the outputs mentioned in your lovely pinout diagram.
1.)Am I right that you used the post vca outputs on pins 25a & c?
2.)The pre resistor for the master reset is 10k in the diagram,but I remember having seen 22k somewhere here in this forum.
Can you explain a bit how to get the right value?I want to pick the -24-ish volts after the filtercaps on a JLM psu.
3.)The fader dc on pin 31b is the input to the vca(s) when the "select fader" button is used on the real console,right(just for info!)?
4.)The 0v connections on pins 15,17 & 18 same as the -18v for audio on pins 19,20 & 22-is it o.k. to make the bridges directly on the DIN connectors or better run single wires to the psu?
5.)Any jumpers to set?
6.)The module has a lot of trim pots at it´s sides for symmetry,0 sets for pot detent etc.In case of my module is not working properly-is there a guide existing for trimming them?I have got a 2 channel-scope meanwhile and signal generators too so I can do some basic measurements.(Just in case.....).

Would be great hearing from you both soon,have a nice weekend,

best,

Udo.

 

[helterbelter]

regarding your question to Neil :

The vca is the most essential part of the fader, so, pre-fader is also pre-VCA.

@Paul:I went trough this thread after a long time.Looking at the pics on the first side I´ve seen no connections to pins 14a+c,the outputs mentioned in your lovely pinout diagram.
1.)Am I right that you used the post vca outputs on pins 25a & c?
2.)The pre resistor for the master reset is 10k in the diagram,but I remember having seen 22k somewhere here in this forum.
Can you explain a bit how to get the right value?I want to pick the -24-ish volts after the filtercaps on a JLM psu.
3.)The fader dc on pin 31b is the input to the vca(s) when the "select fader" button is used on the real console,right(just for info!)?
4.)The 0v connections on pins 15,17 & 18 same as the -18v for audio on pins 19,20 & 22-is it o.k. to make the bridges directly on the DIN connectors or better run single wires to the psu?
5.)Any jumpers to set?
6.)The module has a lot of trim pots at it´s sides for symmetry,0 sets for pot detent etc.In case of my module is not working properly-is there a guide existing for trimming them?I have got a 2 channel-scope meanwhile and signal generators too so I can do some basic measurements.(Just in case.....).

1) Regarding the pic of my first built 552 summingbox : You're right, I used the post VCA insert send as output here.... Maybe I'd better add that to the first post as well. Haven't thought of it when I made the diagram.
2). Yes, I read 22 K also somewhere. That'll probably be better than 10K, because I think it's only there for reducing current. The 10K is something that I learnt from the RA buscards for the lunchboxes. They used it there for the Masterreset pins on 4 modules simultaneously. I do know that some techs don't even put a resistor there, you could connect the pin straight unto the -25v line. I can't give any technical info on it, the master reset goes to a load of switchinghybrids of which I don't know the components.
3). eh, not really sure, but IIRC, the 506/508 fader and front pot work simultaneously. The DC voltages from the 556 faders (the ones that you use when selecting a virtual group on the console) come in on other pins. I'd have to check the CCR papers to tell which pins the 556 set use, but, as said earlier, you'd better not use them that way.
4). The 0v can be bridged at the DIN connector, yes. But I'd wire the audio-18v and the logic (Leds, BU) -18v seperately to the PSU. Even if you use just 1x -18v, you can disconnect the audiovoltagelines later on if necessary.
5). Yes, and no. Depending on configuration (e.g. the external input can be added to the summinginput, or replace it). I'd be happy to send the 552 docs to you, but you'd have to remind me for that.
6). The outputs can be adjusted, the inputs can't. I don't have a document that describes a certain procedure. But you could use a 1000 Hz tone, connect the dualbeam scope, and adjust the trimmer until the positive and the negative lines match. Should be good enough, I think. (but keep in mind :  I'm a diy enthousiast, not an experienced audio electronics engineer).

 

[kante1603]

Wow Paul-that was fast-THX a lot

2). Yes, I read 22 K also somewhere. That'll probably be better than 10K, because I think it's only there for reducing current. The 10K is something that I learnt from the RA buscards for the lunchboxes. They used it there for the Masterreset pins on 4 modules simultaneously. I do know that some techs don't even put a resistor there, you could connect the pin straight unto the -25v line. I can't give any technical info on it, the master reset goes to a load of switchinghybrids of which I don't know the components.

O.K.,both of you have working units,so I´ll go the 10k way.

3). eh, not really sure, but IIRC, the 506/508 fader and front pot work simultaneously. The DC voltages from the 556 faders (the ones that you use when selecting a virtual group on the console) come in on other pins. I'd have to check the CCR papers to tell which pins the 556 set use, but, as said earlier, you'd better not use them that way.

Don´t worry,it was just for info Paul-I remember they worked simultaneously,and I´ve got a lot of faders modules with 10k lin to disassemble here,hahahaha....for hooking up arround more than 30 summing boxes or so ;D

4). The 0v can be bridged at the DIN connector, yes. But I'd wire the audio-18v and the logic (Leds, BU) -18v seperately to the PSU. Even if you use just 1x -18v, you can disconnect the audiovoltagelines later on if necessary.

O.K.

5). Yes, and no. Depending on configuration (e.g. the external input can be added to the summinginput, or replace it). I'd be happy to send the 552 docs to you, but you'd have to remind me for that.

So I think I don´t have to jumper anything when using it just as a summing/makeup stage (but do want to have the pre-insert point).For having this I can put in relais,no biggie.

6). The outputs can be adjusted, the inputs can't. I don't have a document that describes a certain procedure. But you could use a 1000 Hz tone, connect the dualbeam scope, and adjust the trimmer until the positive and the negative lines match. Should be good enough, I think. (but keep in mind :  I'm a diy enthousiast, not an experienced audio electronics engineer).

Oh-You aren´t :
O.K.,will check it and do some trimming only if necessary.

Thank you Paul,I will get this part up and running first,then add on the rest (still a lot of wiring work to do on the NYD stuff-good for christmas time I think).

Wel te rusten,

Udo.

 

[kante1603]

So I took my IMO-module and did the DIN connector-wiring.
Checked out if it works in general.Lights ("Select Fader") on-cool (I thought....).
Figured out that I left parts of my tools at work,including the probes for my scope.....
But I had a Minirator and Minilyzer handy,plugged them in and-SH**T-Minilyzer was overshot and went out of range....
Turning down the level pot to 12 o´clock was o.k. (metering it),but the gain added was arround +30dB or so......
Broken module?Lucky me I had another one lying arround.Checked it-same result.....hmmmmmpfffffff

Hmmmmm.....having  a good cup of coffee.....Aaaaaahhhh-I´m an idiot:It´s a summing amplifier-should put in at least 2 pieces of 10k as summing resistors!!!Soldered a "Quick & Dirty" adaptor and YES!!!-waaaayyyyyy better.Checked the other channel-identical to the first-cool!
Checked the pre-inserts then.Interupting the chain gives no output on post-fader o/p-CORRECT!Level on pre-insert send is identical to the o/p with pot in detent position-Hurray!
Turning the level pot fully clockwise gives nearly +10dB-correct!

Just a little thing:I have a boost of arround +6dB from input to output,but that is probably an issue of my signal source I bet.Don´t know the output impedance of that Minirator,must be very low.Since this is the only signal attached there I think the unit is in it´s normal operation range.
Anyway,the Minilyzer proofs symmetry on all points so the debalance and balancing circuits do their job too.
The summing boxes heart is beating now!

Cannot listen to it,don´t have my headphone amp here at home-but I feel better because I think that I´m on track now.....

am I? ;D

Cheers,

Udo.

 

[helterbelter]

Yes, you're on track, haha. Now you can check all your IMO's for function.


6dB boost, is that from the input to preVCA send ? It could be that the RV3's (1 on each card) are set to maximum. I don't recall reading about a specific jumpersetting for additional boost.....

To be fairly honest, I haven't measured gain settings from input to output, just the differences between left and right. Besides, I'm more a guy that listens to what a piece of audioelectronics does, instead of measuring all the details (except for voltages on the feedinglines of the opamps and logic stuff). If I don't like what I hear, then I start looking for troublesome stuff.
But on the other hand..... 
6dB boost is noticable by hearing, it'd caught my attention. Also, it decreases the headroom significantly. In case the RV3's are set correctly, a shunt resistor would be handy after all. But it would surprise me, I know the 10k resistor method without shunt is commonly used on these summing amps......

 

[kante1603]

Yes, you're on track, haha. Now you can check all your IMO's for function.

If I can get them out if my boxes.....heavy climbing in a very high shelf,remember? :

6dB boost, is that from the input to preVCA send ? It could be that the RV3's (1 on each card) are set to maximum. I don't recall reading about a specific jumpersetting for additional boost.....

Yes,it´s from input to preVCA send as well as postVCA send with the level pot set to detend (0dB).Will investigate the R3-thanks for the hint.Maybe they were set so in our very special setup since their function was to drive our main amps (tons of them) located far away from my F.O.H.,so say about more than 130 meters.But this can be easily checked,thanks Paul

To be fairly honest, I haven't measured gain settings from input to output, just the differences between left and right. Besides, I'm more a guy that listens to what a piece of audioelectronics does, instead of measuring all the details (except for voltages on the feedinglines of the opamps and logic stuff). If I don't like what I hear, then I start looking for troublesome stuff.
But on the other hand..... 
6dB boost is noticable by hearing, it'd caught my attention. Also, it decreases the headroom significantly. In case the RV3's are set correctly, a shunt resistor would be handy after all. But it would surprise me, I know the 10k resistor method without shunt is commonly used on these summing amps......

I think it´s always both of it:Good sounding equipment with good technical data having in mind that this depends on each other.
+6dB means level is doubbled up,so yes,it is audible,hahahahaha.....
I´m pretty shure I can manage it now,otherwise will ask here ("with a little help from my friends-dadapdadapdadap....").
Thinking of  hooking up a bit of NYD´s stuff in the front will cause some additional drop-especially via the lcr switches,so let´s wait and see.And I think i have even an oscillator module arround somewhere (SL559 or so?) as I´m not shure about this old minilyzer (Rev1).
Will report back when I´m done checking this issue.

Good night,

Udo.

 

[kante1603]

So I put one NYD chain together (level pot,mute,lcr and the summing resistors).
Put on the signal generator to the front and measured with the minilyzer after the 10k resistors (not hooked up to the IMO yet).
It was just a quick shot to get one step further.Now guess what the loss in this passive part is:-6dB!
Not a real world setup,but seems to make sense.
Further checks to come,will do the outputs balancing and zero settings next.
If time permitting can somebody of you do a simple measurement with a 1kHz sine at 0dBu on one input channel and tell me the loss or gain on the outputs of your builds is with level at 0dB position?Would be cool to have a comparison to yours!

Thank you in advance,

Udo.

 

[helterbelter]

Hi Udo,

I can only make a partial comparison, because the summing amp that I use only has the summingstage. (the same part as the summinginput to the pre-vca send of the 552). I'll do the test tomorrow.

 

[kante1603]

Hi Udo,

I can only make a partial comparison, because the summing amp that I use only has the summingstage. (the same part as the summinginput to the pre-vca send of the 552). I'll do the test tomorrow.

Hi Paul,

cool,pre VCA send equals the level on post post VCA output in my IMO (I think I have to trim the R3s),therefore seems to be unity gain.

Thank you in advance!

Udo.

 

[helterbelter]

Hey,
not much time for replies, so here's a quick one :
The remaining boost of the summing amp that I used in the lunchbox is.................... 5.9 dB............

 

[kante1603]

Hey,
not much time for replies, so here's a quick one :
The remaining boost of the summing amp that I used in the lunchbox is.................... 5.9 dB............

;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
Hi Paul,
so it seems that my IMO is even set right-without doing anything,hahahahaha........
Anyway,will check for symmtery because I haven´t even used my new (old) Hameg scope-now it is a must

Thank you very much for doing the test my friend;this proofs again being on track (wonder if Neil would have the same results).

Have a nice weekend,

Udo 8)

 

[helterbelter]

Yes,

well, it surprised me. The 10K method is something that I found on the internet, posted by someone who's experienced with racking SSL modules, 5K modules in general. It never occured to me this could be done better. Besides, looking at the buscards of certain SSL summingamps, there are also a few 10K resistors added for an additional input to the summing stage. (I don't recall which buscards though).  I haven't checked the input versus output earlier, but, fwiw, the 552 didn't distort in my tests, even though it might need a shunt resistor after all. Fortunately, it's pretty easy to add a shunt resistor !

 

[kante1603]

I haven't checked the input versus output earlier, but, fwiw, the 552 didn't distort in my tests, even though it might need a shunt resistor after all. Fortunately, it's pretty easy to add a shunt resistor !

Hi Paul,

well,as long as nothing distorts it´s O.K.
Pretty easy to add a shunt resistor....hmmmmm.....but we need two of them-it is stereo-so this doubbles up the work-SH*T ;D ;D ;D.
But to be serious for a second:What do you think would the 552 like to "see" as a good source impedance?

Best,

Udo.