Advice for Router with Attenuators

Hi. First of all I’d like to make it clear that I don’t have any electronics experiences. I’m fairly handy with wood and metal work but never attempted any serious audio DIY. I’ve made a living as a composer and producer for the last 22 years and have considerable studio experience.

So, there’s a piece of equipment that I’d like to either have a go at building or employ someone to do. The main reason is because I can’t find any existing piece that I could buy, without buying a large console, and I think I would find it incredibly useful.

It’s an 8 channel unit. 4 are mono. 4 are stereo. All channels are balanced. Each channel has 2 inputs. One is intended to come from a preamp the other from DAW. A switch selects which input is used. Next the signal goes to an insert send that is always open. The next switch selects the insert return instead of the input, which is then routed to an attenuator. After that we have two further switches to select if we go to output A and or output B.

I’ve attached a picture and a signal flow diagram. I would love for any advice as to how difficult this might be.  Thanks

Signal flow diagram

Seems straightforward. I am impressed by the clarity of description for a professed non- electronics person.

Just one question. How do the stereo channels differ; on particular the routing to the A and B buses?

Cheers

Ian

Thanks. I spend a lot of time reading manuals!

The stereo channels would just have two of everything, so there would be dual Mic Pre inputs, dual DAW inputs, dual sends, dual returns, dual bus A outs, dual bus B outs. All the bus A outputs will go to one external summing bus; B outputs to a second external summing bus. The summing units will have the pan pots.

If anyone has any links to other similar threads it would be super useful. I guess splitters / mults, switches and Attenuators and the things I need to learn.

And I need to find is the highest quality components. And some big chunky knobs!

temas said:

Thanks. I spend a lot of time reading manuals!

The stereo channels would just have two of everything, so there would be dual Mic Pre inputs, dual DAW inputs, dual sends, dual returns, dual bus A outs, dual bus B outs. All the bus A outputs will go to one external summing bus; B outputs to a second external summing bus.

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Except you stereo front panels only have one set of controls; shouldn't they have 2 of everything according to the above description?

The summing units will have the pan pots.

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Pan pots? What pan pots.?This is the first time you have mentioned them. Pan pots do not really make sense in the context of summing units or have I missed something?

Cheers

Ian

ruffrecords said:

Except you stereo front panels only have one set of controls; shouldn't they have 2 of everything according to the above description?

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All the switches on the stereo channels will affect left and right sides simultaneously. And the attenuator will be stereo.

ruffrecords said:

Pan pots? What pan pots.?This is the first time you have mentioned them. Pan pots do not really make sense in the context of summing units or have I missed something?

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Panning and Summing will all be done externally after the signals have left the unit. For example I have a Phoenix Audio Nicerizer, which will receive the 12 signals from the each of the 12 channels’ Output A (labelled Bus A on the front panel). The Nicerizer has 16 inputs with a pan knob for each channel.

temas said:

All the switches on the stereo channels will affect left and right sides simultaneously. And the attenuator will be stereo.

Click to expand...

So deoes each stereo channel have 2 separate bus A and two  separate Bus B outputs?

Panning and Summing will all be done externally after the signals have left the unit. For example I have a Phoenix Audio Nicerizer, which will receive the 12 signals from the each of the 12 channels’ Output A (labelled Bus A on the front panel). The Nicerizer has 16 inputs with a pan knob for each channel.

Click to expand...

So the unit has not buses internally. All the Bus A signals are not summed inside it. On the back of it there will be a Bus A and Bus B output for each channel (two each for stereo).

Cheers

Ian

Yes, yes and yes!  Many thanks for your perseverance.

The mono channels would have 2 inputs, 2 outputs, 1 send & return. The stereo channels have a total of 4 inputs, 4 outputs, 2 sends & 2 returns. Total stereo operation from the front panel controls for the stereo channels.

I know your next question will be why would I want a stereo channel with only one volume control for 2 mono preamps. Well, most of the time I track stereo sources and even if they are dual mono I would be sending the signals to the DAW pre fader, monitoring post DAW. There will be four mono faders there for the times I do really need them, but essentially these faders / attenuators are mostly to be used for 'final touch' mixing and mastering. Once the mix is 95% complete I'll send 12 DAW stems > Outboard > Faders > 2 Stereo Busses > Outboard > DAW.

What I'm trying to build here is basically eight Goldpoint passive attenuators with a few additional options in a box that matches to some extent my Shadow Hills GAMA 8.

Right, I've modified my design a little, which I think makes it much more useful. The signal path is now slightly more complex and I now require 3 knobs per channel, but I will only require 6 channels instead of 8. All channels will now be the same.

There is now a dedicated stereo attenuator for the DAW signal and dedicated dual mono attenuators for the dual mono mic pre signals. The mic pre signals can now be routed to either of the stereo outputs at the same time as the DAW signals are being routed to the other stereo outputs. Of course only one pair of inputs can use the inserts at a time.

I think I'm now way out of my depth for what I can hope to build myself, but would appreciate any feedback or thoughts.

Thanks again.

...and the signal flow....

Each channel has 2 inputs. One is intended to come from a preamp the other from DAW. A switch selects which input is used. Next the signal goes to an insert send that is always open. The next switch selects the insert return instead of the input, which is then routed to an attenuator. After that we have two further switches to select if we go to output A and or output B.

Click to expand...

Welcome to gdiy, temas. Thought I'd mention your requirements are near to what I wanted in a daw interface as well, and took a similar route in front of mixer channels.  Look forward to seeing your build!
-Boji

So just to be clear , are your mono channels actually dual mono?

Cheers

Ian

boji said:

Welcome to gdiy, temas. Thought I'd mention your requirements are near to what I wanted in a daw interface as well, and took a similar route in front of mixer channels.

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Thanks. What was your solution? And did you build it or buy an existing  product? The SSL XDesk is the only product I can think of that is remotely similar, but even that isn’t as flexible.

ruffrecords said:

So just to be clear , are your mono channels actually dual mono?

Click to expand...

Thanks Ian.

Each of these units would have 2 mono inputs and 1 stereo input. The 2 mono inputs would each have their own attenuator with the intention being for them to receive signals from mic preamps. The stereo input would have one stereo attenuator to receive a stereo signal from the DAW.

Having searched through the forum for similar designs, I have read that splitting a passive signal to two outputs after attenuation might cause the volume to be different at the outputs.

The other thing I haven't worked out is what the best method is for my input switch (labelled 'Insert'). There are three (stereo) functions / actions being carried out with this one switch and I've yet to find an existing example of how this is done.

Thanks again