4U or 5U 500 series frames

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Hi Ian,

Not a problem.

Below is the preliminary card edge pin configuration.  It obviously does not include the HT and heater power connections. 

The current card edge connector's insulation resistance has a rated test voltage of 500VDC. If you can all advice on the maximum HT voltage that we may use then the current edge connector might be fine. In which case I would use a separate 6 pin (2X6) version for the HT and heater.
 
Is this still using the edac style edge connector? Having 500 series compatibility would be attractive.  But if it's a new format then might as well go all out.  No reason to not use both sides of the connector so you get double the connections,  could do 8 buses,  24v relay power and ground,  digital pins,  etc. 
 
It is.

I agree on using both sides of the connector for at least signals. The current rating of the contacts is 3A. 

I will revise the pin configuration with your comments taken into account.

500 compatibility will naturally need to go out. But even with the old proposal I was sceptical because the adapter panels would be very expensive. 

 
sahib said:
Hi Ian,

Not a problem.

Below is the preliminary card edge pin configuration.  It obviously does not include the HT and heater power connections. 

The current card edge connector's insulation resistance has a rated test voltage of 500VDC. If you can all advice on the maximum HT voltage that we may use then the current edge connector might be fine. In which case I would use a separate 6 pin (2X6) version for the HT and heater.

Maximum HT voltage is 300V.

Cheers

Ian
 
V2 of the card edge pin configuration.

The Solid State side card edge connector is 44 pin. The tube card edge connector  below is 12 pin. I have kept the tube card edge separate as I would like to have a good separation from the SS side.

I included  unregulated + - 24V which might be overkill but it can easily be derived from the unregulated side of + -16V. This would be around 22V which would be more than sufficient to operate 24V relays.

As I mentioned before the contact rating of the card edge connector is 3A. I would imagine it would be sufficient for heater connection even if it is at 6VDC.  If not we can compromise with 56 pin connector and double up.

I have deliberately  grouped all the signal lines on top as this gives me an uninterrupted area on the backplane.

But please do comment.
 
sahib said:
V2 of the card edge pin configuration.

The Solid State side card edge connector is 44 pin. The tube card edge connector  below is 12 pin. I have kept the tube card edge separate as I would like to have a good separation from the SS side.

I included  unregulated + - 24V which might be overkill but it can easily be derived from the unregulated side of + -16V. This would be around 22V which would be more than sufficient to operate 24V relays.

As I mentioned before the contact rating of the card edge connector is 3A. I would imagine it would be sufficient for heater connection even if it is at 6VDC.  If not we can compromise with 56 pin connector and double up.

I have deliberately  grouped all the signal lines on top as this gives me an uninterrupted area on the backplane.

But please do comment.

While I like my configuration, and have been using it with my modules, I think it would be a good idea to have 2 sets on ins and outs.  Just my $0.02
Best,
Bruno2000
 
I will need to do some thinking about the connections. Are there any existing standards we could draw from, perhaps from an established console infrastructure? It can sometimes be hard to anticipate things until you actually start making the modules.

I would be happy with just metalwork and then user designed backplane as well. Gives a lot of flexibility, something like the eurorack but geared towards audio with the appropriate connections, xlr, db25, etc.

Another possible option is something like the SSL X-rack. The backplane only supplies power or control signals. Each individual modules provides it's own appropriate audio connectors.
 
bruno2000 said:
While I like my configuration, and have been using it with my modules, I think it would be a good idea to have 2 sets on ins and outs.  Just my $0.02
Best,
Bruno2000

Totally agree. In fact Ian requested the separate balanced line/in outs.  We later decided to omit them due to lack of pins on the connector. However, we can move up to 60 pin  connector and use a single connector for both the ss and tube connection.


john12ax7 said:
I will need to do some thinking about the connections. Are there any existing standards we could draw from, perhaps from an established console infrastructure? It can sometimes be hard to anticipate things until you actually start making the modules.

I have two trunks full of console service manuals. There is no end to it.

However,
I would be happy with just metalwork and then user designed backplane as well. Gives a lot of flexibility, something like the eurorack but geared towards audio with the appropriate connections, xlr, db25, etc

Another possible option is something like the SSL X-rack. The backplane only supplies power or control signals. Each individual modules provides it's own appropriate audio connectors.

is a good proposal.  I'll split the signal and power connections. We can have the power backplane at the bottom  and the audio backplane on the top. For those who wish to design their own audio backplane I can provide the dimensions for the connector positions on the rear panel.

On the audio backplane my plan is to have the XLRs for the main inputs/outputs, TRSs for the auxiliary unbalanced output and insert points. Finally  all the signal lines will also be available at boxed headers for either direct access through ribbon or subD25 connection.

I'll update the table.
 
Here is V3.

The backplane is split into two. The bottom half has the 30 pin (2 x 15) card edge connector and the top half has the 24 pin (2 x 12).

Second balanced in /out pair is incorporated.

What do we think?
 
I like it! All the signals you could wish for on one connector and all the power you would ever need on the other. Remind me how is the stereo link wired? Does it just connect pins of adjacent pairs?

Cheers

Ian
 
Thank you Ian.

Link simply connects to the same pin on the adjacent slot. It will be jumper selectable as usual.

I'll sketch out the mechanics tonight.
 
jdbakker said:
I would like to have audio GND closer to the (single-ended) buses, to reduce return loop area.

On the power connector, I would prefer the outermost pins to be GND as well (even when you won't be hot plugging).

JDB.

I was expecting this whack on my neck. As how it is in the previous versions. I'll pull it down.

What do we think of the attached sketch?  It is the rear view.

The blue lines are module width, the green are module centres. The edge connector centres are not shown. They are  off-set to the module centers.

The area outlined in yellow is a bit exaggerated. I have to see the power connector situation here but in any case we will have the on/off switch for remotely controlling the power supply and the status LED for the rails here. There are two separate connectors for SS and tube powers respectively.  I'll design the power supplies too.

The case will be 1" deeper than the standard 500 depth. The power and audio backplanes will sit in the front at the 500 depth. Of course nothing stops us from making the rack deeper.

There will  be a full size backplane for the connectors which will mount onto the rear panel and connect onto the audio backplane through 26 WAY ribbons.

Unfortunately we are going to have to have a separate rear panel for SubD25 connections as there will be 6 of them, and there is simply not enough space,  unless we add on another 1U.

For balancing the insert points (optional) I will incorporate a single row locking header on each slot on the audio backplane for little daughter boards. I would normally use THAT line drivers but the users can design their own if they wish to.

The provision for output TXs for the two main outputs were also discussed. This was Ian's request. Obviously we just have to see the available space which in return will dictate the size and shape of the transformer.

My preference would be to make the rack deeper to allow the transformer to be incorporated within the module design.  With this in mind I will incorporate guide rails.

Edit: I  see I missed a couple of mounting holes.
 
For 500 series,  what is the internal distance from the inside of the front face plate to the backplane? Will you be keeping this same distance?
 
That is 158.07mm. 

I am keeping this but as I mentioned before we can go deeper as at the end of the day this is a new design.
 
sahib said:
That is 158.07mm. 

I am keeping this but as I mentioned before we can go deeper as at the end of the day this is a new design.

Is that a published number? I calculated it to be 5.938 + .020 (tolerance) + .155 (edac) = 6.113" min or 155.27mm. But could never find an actual spec.  Just curious.

For the new rack, I think keeping it the same is a good starting point as it makes it easier to modify an existing 500 series design to a new format.
 
My apologies.

On our racks the card edge connector sits 0.1" higher (using spacers) due to the extra height we needed for the balancing card. Therefore it should be indeed 155.27.

I have  been a bit generous with the connector layout. There is another version. I can get the SubD25 connections for the main IOs and the auxiliary unbalanced outputs.

However, I would not imagine the insert points will require SubD25 connection.

We are keeping the standard 500 depth.

 
I have a question regarding the mechanical aspects. I use Eurorack  for several reasons but one is because it provides card guides for the PCBs which the 500 system does not. Ideally I would like to be able to use the backplane with standard Eurorack front and rear horizontal extrusions in mixer builds because their card guides fit into these.  At the same time, I would like DIYers to be able to build the boards and fit them straight into one of your racks. The problem is, I do not know if the intended depth of the new standard PCBs wll be the correct for the spacing required to fit the Eurorack card guides. I could make boards for mixers a different depth so they are Eurocack compatible but I would rather not have to. I like the additional mechanical integrity that card guides give so I would also rather not do without them.

Cheers

ian
 
Back
Top