Test Rig for 51x Modules

[saxmonster]

Ok, So i got 2 pcbs from a member on here.

I am going to build a rig for testing outside the rack.  I am getting an sb4001 kit from someone who did not build theirs.  I just wanna make sure my thinking is correct so I don't blow anything up.  I wanna build a dual rig for the double card modules and also of course single card modules.

Here are the 2 pcbs, see pic below.

If I build a new 7-core 51x psu cable to come out of the 51x power supply to the 1st pcb can i then run another 7core wire from that 1st pcb to the second one?

I won't need any caps or resistors to change the power at all correct?  Its basically just like the pcb already in the rack.


Are these the Xlr Connectors to use?

http://www.mouser.com/Search/ProductDetail.aspx?R=NC3MBVvirtualkey56810000virtualkey568-NC3MBV

http://www.mouser.com/Search/ProductDetail.aspx?R=NC3FBV1virtualkey56810000virtualkey568-NC3FBV-1



Of course I will get the 7core wire, headers / shunts and also the 36 card edge connectors from Jeff. 

What size heat shrink should I get for the 7core wires when attaching to the new 7pin female cable mount.

Still a newbie at this stuff.

TIA
-Scott

 

[3nity]

You can use really anything there, just hard wired stuff...
Thanks.

 

[dmp]

Just saw this. Since I made the pcbs, I should speak up.

If I build a new 7-core 51x psu cable to come out of the 51x power supply to the 1st pcb can i then run another 7core wire from that 1st pcb to the second one?

Yes, I made these so they could be daisy chained together so there are two pads for each voltage. The only exception is the 'link' which has a jumper to link / unlink boards.
I attached a picture of a built up board. Note that the chassis connection from the psu is going to the 'chassis' on the board with a little bolt at the mounting screw.
Also note that the ground jumpers should be in 'B' in almost all situations... this allows options for connecting the audio ground and chassis.

I won't need any caps or resistors to change the power at all correct?  Its basically just like the pcb already in the rack.

It doesn't need anything if you have a 51x psu.

Are these the Xlr Connectors to use?

I used NC3MAV and NC3FAV. The B series just has a metal ring instead of plastic but look like they will fit

What size heat shrink should I get for the 7core wires when attaching to the new 7pin female cable mount.

I'd say something small, 1/8" or 3/32". Heat shrink is pretty forgiving. Redco sells it by the foot in these sizes. I have a selection so I'm not sure what I'd grab...

 

[saxmonster]

Thanks again Dmp for a great Pcb,

I have headers for the GND boxes and was going to put the shunts over the middle one and the one that has the B under it.  Is this the correct way for audio ground to chassis.  Can you describe how the link box works.  What exactly does the link on your pcb or even the stereo link headers on the 511 rack actually do.  I can't find that much info in the threads on it.  Basically there is talk about the pin1 to ground or chassis debate but no clean definition on the stereo links.  I should have picked up one of those green things so I wouldn't have to solder to your pcb.

Thanks again
-Scott

 

[dmp]

I have headers for the GND boxes and was going to put the shunts over the middle one and the one that has the B under it.

That is fine.

What exactly does the link on your pcb or even the stereo link headers on the 511 rack actually do.

The link is pretty simple - it is a pin in the 500 spec that can be connected or not between modules. The link on my pcb and in the 511 rack just connect those two pins between the modules (so they have continuity).
So for instance, the LA3A and 525 compressors by Peter have a 'link' function where two compressors can be linked to make the GR the same for a stereo bus.
Both put a control voltage on the link pin of the rack, and if the link pin is connected between the two, they are 'linked'.
I'm making this sound confusing when it is really simple!
The reason you need the jumpers is if you have a pair of LA3As and a pair of 525s in the same rack, all 4 modules can't be sharing the link. You have to jumper (connect) the link of just the two pairs.

 

[saxmonster]

Still a little confused on how the linking works.  I know what you are saying but i guess in deeper though how does it allow the 2 compressors to communicate?  Like if the first La3a is at a GR of 4 does it say to the other La3a that it should also be doing a GR of 4 even if its slightly off?  Almost like a master and a slave type setup.  So that the two are perfectly equal?  Thats what you need on a stereo buss.  Just trying to wrap my head around all this.  Also what is the part number for the green screw connector?  Thanks again.

-Scott

 

[dmp]

You could look up the stereo linking board for a 1176 to get more details. I think most compressors do it in a pretty similar way - they basically calculate a control voltage for the gain reduction and then send it to something like a mix bus - which is connected between the two compressors over the link pin. So if compressor A has a cv of 5v and compressor b is at 3v they'll be 'mixed' - 4v or something like that.
When linked the GR should be perfectly equal in a perfect world

Also what is the part number for the green screw connector?

Sorry I don't know - I just pulled that out of a bin in my shop. If you measure the spacing of the holes you should be able to find them on mouser or digikey. If you can't find them let me know and I'll try.

 

[Matador]

Also what is the part number for the green screw connector?

Those look like Phoenix Contact green screw terminals.

DMP, what is the pin pitch for those connectors on your board?  It looks 3mm to 3.5mm just based on my eyeball of it.

 

[saxmonster]

Yea Jeff has them in the PSU kit but I don't see where they can be bought separately on his site or what the part number is.

 

[dmp]

I don't have one here to measure.

Saxmonster: measure the spacing between the holes in mm.
Go to mouser and select that pitch

http://www.mouser.com/Phoenix-Contact/Connectors/Terminal-Blocks/Fixed-Terminal-Blocks/_/N-7rqd7?P=1z0zljm&Keyword=phoenix+contact&FS=True

 

[abbey road d enfer]

Still a little confused on how the linking works.  I know what you are saying but i guess in deeper though how does it allow the 2 compressors to communicate?  Like if the first La3a is at a GR of 4 does it say to the other La3a that it should also be doing a GR of 4 even if its slightly off?  Almost like a master and a slave type setup.  So that the two are perfectly equal?  Thats what you need on a stereo buss.  Just trying to wrap my head around all this.  Also what is the part number for the green screw connector?  Thanks again.

-Scott

The principle there is "follow the leader". The link bus is designed in such a way that whatever channel has the highest GR will force the other. It's an analog "OR" gate.

 

[abbey road d enfer]

You could look up the stereo linking board for a 1176 to get more details. I think most compressors do it in a pretty similar way - they basically calculate a control voltage for the gain reduction and then send it to something like a mix bus - which is connected between the two compressors over the link pin. So if compressor A has a cv of 5v and compressor b is at 3v they'll be 'mixed' - 4v or something like that.

Not exactly. As I wrote in the precedent post, the channel that has more GR forces the other. In a VCA-type compressor, this is generally done by simply linking the two channels directly, but on 1176's there is a significant DC offset between the links; that's why there is a dedicated box that comprises a dry battery and a trimmer that must be connected between the two units.
Now there are exceptions to the rule; some compressors have a secondary input that receives the other channel and the input signals are mixed before being rectified.

 

[dmp]

Hum... I'm sure different compressors link in different ways. The 1176 does look like a 'or', taking a maximum of the CV.
But the LA3A seems like it would be an average since it is connecting the collectors in the GR amp. It doesn't have a rectifier like the 1176.
I may be wrong though.
Anyway, the point is that the GR of two compressors are 'linked' to be equal.

 

[abbey road d enfer]

As I said, there are exceptions. But in order to achieve equal GR on both sides of a stereo signal, and maintain overload protection, analog "OR" is the accepted way to go.

 

[SSLtech]

Stereo linking is a whole subset; -it's demonstrated admirably by the 'turbo' board on the GSSL.

The GSSL -as standard- takes the sum of the two audio signals and controls both channels with that.

The ORIGINAL unit (SSL G384) takes the GREATER and applies it to both... -an 'analog or'. (this is the mod effected by adding the 'turbo' board to a GSSL)

DBX compressors -so far as I've seen- use true RMS summing and apply that to both. (VERY different to both previously mentioned methods)

The 1176 doesn't actually apply the maximum to both... at least not in the versions which I've seen. -Simple test of applying 3dB GR and linking a second 1176 with NO gain reduction results in the 3dB GR *reducing* when the units are linked.

As to what is 'best', opinions may differ. Experience has led me to conclude that MOST times the 'or' version is preferable when signal is to be constrained by peak level on either channel (broadcast chain, for example), but when squashing a SUBSET of the overall peak level (for example a bass/drum rhythm SUB-mix which does not absolutely define the overall program material's peak envelope), there have been occasions when the GSSL 'simple-sum' method has sounded preferable.

Since perceptions will differ and depend on several circumstances, better if we avoid identifying any approach as simply universally 'better', although in the majority of cases I agree that 'or' (highest instantaneous requirement of any one is applied to ALL) generally works best.

 

[abbey road d enfer]

DBX compressors -so far as I've seen- use true RMS summing and apply that to both. (VERY different to both previously mentioned methods)

It looks like there's almost as many different linking schemes as there are dbx compressors. It goes from audio summing to analog OR to rms OR via rms summing.

The 1176 doesn't actually apply the maximum to both... at least not in the versions which I've seen. -Simple test of applying 3dB GR and linking a second 1176 with NO gain reduction results in the 3dB GR *reducing* when the units are linked.

That's because the analog OR'ing is done after the Atk control. When the Atk is set towards the fast settings, the OR will be near perfect, but when set towards slow, the control voltages will tend to average. In particular if one channel is fast and the other slow, it will tend to be ignored.

 

[saxmonster]

I don't have one here to measure.

Saxmonster: measure the spacing between the holes in mm.
Go to mouser and select that pitch

http://www.mouser.com/Phoenix-Contact/Connectors/Terminal-Blocks/Fixed-Terminal-Blocks/_/N-7rqd7?P=1z0zljm&Keyword=phoenix+contact&FS=True

Do I measure from the edge of one hole to the edge of the next one or from the middle of the hole to the middle of the next hole?
I printed out a mm ruler and will measure it with that.

-Scott

Ok so from middle to middle its 5mm from right edge of hole one to left edge of hole two its 3.5mm.

Can anyone else measure?  Not sure if anyone else has one.

 

[saxmonster]

Ok so you measure from center of hole to center of hole.

I will be ordering these.

5pin
http://www.mouser.com/Search/ProductDetail.aspx?R=1729047virtualkey65100000virtualkey651-1729047

2pin
http://www.mouser.com/Search/ProductDetail.aspx?R=1729018virtualkey65100000virtualkey651-1729018

 

[dmp]

I just looked at a board and you've got it
parts look correct

 

[dandeurloo]

I thought I might show you guys something I did with Dan's PCB's.

Here is the internal veiw.