ruffrecords

Neve 1883 routing module schematic
« on: April 07, 2014, 08:12:04 AM »
Looking fro the schematic or at least the block diagram for the Neve 1883 routing module as used in the 8104 console.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


Chris

Re: Neve 1883 routing module schematic
« Reply #1 on: April 07, 2014, 10:25:10 AM »
A little rough...

ruffrecords

Re: Neve 1883 routing module schematic
« Reply #2 on: April 07, 2014, 02:11:35 PM »
A little rough...

Brilliant! Thanks very much especially for including the schematic. That confirms a number of assuntion I made.

I have just one question remaining. The switches that select the Cue or Foldback sends. Are these mechanically interlocked to prevent you trying to send to both cue buses or to both foldback buses or is it just assumed no one will ever do something that daft?

I should know the answer to this myself as I was at Neve from 1973 onwards and I did plenty of customer acceptance checks on desks like this that I ought to  know if the switches were interlocked or not. However, the only mechanically interlocked isostats I remember were in monitor selectio banks.

Anyone have an 8014 the check???

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

API

Re: Neve 1883 routing module schematic
« Reply #3 on: April 08, 2014, 06:31:51 AM »
Hi Ian.

No, they are not interlocking and you can send to all four places if you like!
May i ask why you are curious about this?

ruffrecords

Re: Neve 1883 routing module schematic
« Reply #4 on: April 09, 2014, 05:23:15 AM »
Hi Ian.

No, they are not interlocking and you can send to all four places if you like!
May i ask why you are curious about this?

I am curious about it because I am thinking of modelling the routing unit for the Mark 3 tube mixer on it. Attached is my first draft block diagram of the Mark 3 routing module which prompted the question. In my version, group routing is exclusive as this relieves the load on the pan pot and I have separate pots for each AUX send.

Cheers

Ian


Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: Neve 1883 routing module schematic
« Reply #5 on: June 06, 2014, 06:46:45 AM »
Hello everybody!

Want to ask some moments regarding 1883 module.
Here is original block schematic:

Here is my redrawed block schematic without some unprincipled elements:

Short description:
Balanced signal goes from LO1166 output transformer of 1073 style preamp to 10368 line in transformer of 1883. Then unbal signal goes to first BA283AM amp loaded with T1310 choke. After signal goes from pin F of BA283AM to mute switch and then to channel fader and pre fader auxes. After fader signal goes to the second BA283AM loaded with LO1166 trans. After second BA283AM amp signal goes to post fader auxes and four group outputs. Pan pot could be applied for group outputs.

More then that I found some info for 1943 route module. It's same as 1883 but contain 8 group outputs and 8 auxes.

My question regarding number of outputs to group buses. How much lines could be used from second BA283AM without signal loosing? At what factor this depends?
« Last Edit: June 06, 2014, 06:52:19 AM by dirty1_1garry »

ruffrecords

Re: Neve 1883 routing module schematic
« Reply #6 on: June 06, 2014, 12:24:19 PM »

More then that I found some info for 1943 route module. It's same as 1883 but contain 8 group outputs and 8 auxes.

My question regarding number of outputs to group buses. How much lines could be used from second BA283AM without signal loosing? At what factor this depends?

It all boils down to what is the minimum load the BA283AM can drive. We know that via a transformer it can drive a 600 ohm load. The transformer is 1:2 ratio so to the BA283 that looks like 150 ohms. So we know it can drive 150 ohms.

Now, the 'standard' bus feed resistor for Neve mixers was 15K. If you have 8 AUxes turned right up, each with a 10K pot and a 15K bus resistor then each AUX loads it by 6K so 8 of them look like 750 ohms. If you also route 8 buses at once without the pan pot, you have another 15K/8 = 1875 ohms . The two together in parallel load the BA283 with 535 ohms. This is still a much lighter load then the 150 ohms it already sees. If you had 16 buses they would look like 15K/16 = 937 ohms. This in parallel with the AUX sends of 750 ohms looks like 416 ohms. This is still comfortably above the 150 ohms it is happy with.

So, I would say 8 AUXes and 16 buses would be fine.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: Neve 1883 routing module schematic
« Reply #7 on: June 07, 2014, 11:23:03 AM »

If you also route 8 buses at once without the pan pot, you have another 15K/8 = 1875 ohms.

Regarding panorama potentiometers. What will be with pan pot? How this fact will change bus impedance?
1883 module use 10K lin double pot with 2K2 resistor in parallel.
If we use pan pot it will give 5K in middle position (signal in centre pan) for both buses (for example if it's just two)
So we will have 15K bus resistor plus 1527Ohm (5K+2K2 in parallel) = 16K527. Right?

Regarding value of pan pot. Neve modules use double 10K pots with 2K2. What purposes of 2K2? 
In some schematics I saw 47K pot or just single pot. Which way and why better?)

ruffrecords

Re: Neve 1883 routing module schematic
« Reply #8 on: June 08, 2014, 06:12:08 AM »

If you also route 8 buses at once without the pan pot, you have another 15K/8 = 1875 ohms.

Regarding panorama potentiometers. What will be with pan pot? How this fact will change bus impedance?
1883 module use 10K lin double pot with 2K2 resistor in parallel.
If we use pan pot it will give 5K in middle position (signal in centre pan) for both buses (for example if it's just two)
So we will have 15K bus resistor plus 1527Ohm (5K+2K2 in parallel) = 16K527. Right?

I did it without the pan pot because I thought it was probably the worst case. With the pan pot in it gets harder to work out because it is not obvious what pan pot position to use for worst case. If it is fully left or right, then only half the bus resistors are connected So you have 4 x 15K, 2 x 10K and 1 x 2.2K in parallel, which is 3.75K // 5K // 2.2k which is 2.14k //2.2k = 1086 ohms. So it is actually worse than 8 bus resistors alone.

With pan in the middle the top half of each pan pot is 5k // 2.2k = 1527 ohms
The bottom half of the pan pot is 4x15K // 5k = 3.75k // 5k =  2142 ohms

So each pot in total is 1527 + 2142 = 3669 so the load is half this or 1834 ohms - surprisingly close to the  no pan pot case.

Quote
Regarding value of pan pot. Neve modules use double 10K pots with 2K2. What purposes of 2K2? 
In some schematics I saw 47K pot or just single pot. Which way and why better?)

Neve used linear pots for pan pots because the two tracks are better matched. However, a linear pot would give a 6dB dip in the centre position (half way) when something nearer to about 3dB is required. At the centre the top half of the pot is 2.2k // 5k = 1527 ohms. With four buses routed the bottom half is 2142 so the attenuation is 2142/ (2142 +1527) = 0.5838 = 4.6dB. With one bus routed it would be 3750/(3750 + 1527) = 0.710 = 2.96 dB

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'