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Using a volume pedal on the main output

Using a volume pedal on the main output
« on: November 28, 2018, 03:56:11 AM »
Hello,

Here i the situation. I dont want to use the pedal inputs on my p12 because im using them to control the filters on both layer a (pedal 1) and layer b (pedal 2), just so its clear that i cant use them. I want to use a volume pedal after main output A to control the volume of layer A, and i want to use another volume pedal after main output B to control the volume of layer B. From these two volume pedals i want to sum both signals into a third volume pedal where i use two mono splitters to sum "Layer A and B Left" into the third volume pedals Left input, and sum "Layer A and B Right" into the third volume pedals Right input. From there on i want to send the summed signal into a "Passive mixer" (which is the place where i sum the signals from "layer A and B P12", "Ob6" and "Pro 2"), and then send the "master stereo signal" which is the sum of these 4 stereo signals, to the sound technicians mixer.

Visual representation:

Pro 2 Stereo -----> Volume Pedal Stereo ----------------------------------------V
                                                                                                                        V
      L------V                L--------->Splitter A*--------V                                        V                                                 
P12A        Volume Pedal                                     V                                        V
      R------^               R--------->Splitter B*----V    V                                        V
                                                                        V    V                                       V
                                                                   Volume Pedal Stereo -------> Passive Mixer Stereo ------> Sound Engineer
                                                                         ^    ^                                      ^
      R------V                R--------->Splitter B*----^    ^                                       ^
P12B        Volume Pedal                                      ^                                       ^
      L------^                L--------->Splitter A*----------^                                       ^                                                         
                                                                                                                        ^
Ob6 Stereo  -------------------------------------------------------------------------------^

*Remember that there is only one Splitter A and one Splitter B. Splitter A sums the signal of P12A LEFT and P12B LEFT, and Splitter B sums the signal of P12A RIGHT and P12B RIGHT.

I hope this explanation makes sense.

I have some questions to this setup:

1: Will this setup create a lot of noise?

2: Are there any arguments against having a volume pedal after the main outs on the prophet 12? If yes then what are the arguments?

3: Will sending the Left output of P12A and the Left output of P12B via a splitter into the same mono input on the volume pedal be damaging to both signals? And are there other things this might cause that are relevant to consider?

4: Will having two volume pedals after each other do damage to the signal even though volume pedals are passive and dont amplify the noise floor of the signal? Are there other aspects to this that are relevant to consider?

5: Will summing all 4 synths into a passive mixer be damaging to the signal even though the mixer is passive? Are there other considerations regarding this?

6: Are there any sound quality drawbacks to summing the synths in a mixer of my own before sending it to the sound engineer? Sound quality wise, why would i want to give the sound engineer 4 stereo signals instead of just 1?

7: Would DI-boxes be important in a setup like this? If yes; how many? where would they be placed? and why?

Considerations before commenting:
-Simplifying the setup with fewer controllers because "why would you have so many controllers in the first place" is not relevant for what i want.
-I dont know so much about signals, impedance and what is important to consider when dealing with electronics, so layman explanations would help allot.
-I know that i the cable length of the chain should be as short as possible, so no need to point that out unless its relevant to something else, or if it contains more specific details like actual lengths, materials etc.

Thank you so much for reading all of this. I hope we can share ideas and figure some stuff out :)
« Last Edit: November 28, 2018, 04:04:58 AM by Tarjeijazz »

Re: Using a volume pedal on the main output
« Reply #1 on: November 28, 2018, 05:04:04 AM »
Not the full answer! but for what it's worth I run my P12 in 'quad'. I use 2 stereo volume pedals A and B which give me control over the relative volumes of the voice parts, and I use expression controls to alter the relative L and R volumes for each voice part. for some of my voices (depending on how I programmed them) it means I can move the sound around in 3 dimensions. I have no noise issues except that 2 of my 4 (crap) Boss FV500L pedals make noise - so they are the 2 I use for expression instead of output.
 I was advised by a friend not to use splitters without taking technical advice, so I leave that part of your question to the experts. I also believe it is essential to have audio leads the same length to keep the phase of waves intact.

Re: Using a volume pedal on the main output
« Reply #2 on: November 28, 2018, 05:11:47 AM »
Sorry to be unhelpful but I don’t think these are truly answerable questions.
It’s like asking how much food cost, there are too many variables to give a correct answer.
How do you define what ‘a lot of noise’ is for example?
How noisy it is will depend on the spec and performance of the pedal, leads and mixer and whether that ends up too noisy or not is subjective.
There’s no point taking a stereo signal and making it mono though imo. Either work in mono from the start or just take the stereo signal from both pedals straight to the mixer - this would eliminate the need for using splitters and a 3rd volume pedal.
The best ‘summing’ of signals will be on the Prophet 12 itself. It makes no sense to take stereo signals, separate them into mono signals and sum them back in the 3rd volume pedal.
If you’re going to do that you may as well just take a mono signal from the P12 to begin with.
So rather than using the separate outputs of Layer A & Layer B, splitting them, then summing them in the pedal, just place stereo feeds directly from your pedals into your mixer or take mono feeds from the Layers to your volume pedals.
« Last Edit: November 28, 2018, 05:15:40 AM by jazzygb1 »

Re: Using a volume pedal on the main output
« Reply #3 on: November 29, 2018, 12:20:53 AM »
Not the full answer! but for what it's worth I run my P12 in 'quad'. I use 2 stereo volume pedals A and B which give me control over the relative volumes of the voice parts, and I use expression controls to alter the relative L and R volumes for each voice part. for some of my voices (depending on how I programmed them) it means I can move the sound around in 3 dimensions. I have no noise issues except that 2 of my 4 (crap) Boss FV500L pedals make noise - so they are the 2 I use for expression instead of output.
 I was advised by a friend not to use splitters without taking technical advice, so I leave that part of your question to the experts. I also believe it is essential to have audio leads the same length to keep the phase of waves intact.

Thanks for the answer :)

What do you mean by running it in quad?
Your setup sounds cool! Do you know anything regarding what kind of technical advice your friend was talking about? could you ask him? or maybe someone else here could elaborate on that?

And audio leads are cables right? do you mean keeping the L and R of one voice the same length, or do you mean keeping the A output of layer A and the B output of layer B the same length :)?

Sorry to be unhelpful but I don’t think these are truly answerable questions.
It’s like asking how much food cost, there are too many variables to give a correct answer.
How do you define what ‘a lot of noise’ is for example?
How noisy it is will depend on the spec and performance of the pedal, leads and mixer and whether that ends up too noisy or not is subjective.
There’s no point taking a stereo signal and making it mono though imo. Either work in mono from the start or just take the stereo signal from both pedals straight to the mixer - this would eliminate the need for using splitters and a 3rd volume pedal.
The best ‘summing’ of signals will be on the Prophet 12 itself. It makes no sense to take stereo signals, separate them into mono signals and sum them back in the 3rd volume pedal.
If you’re going to do that you may as well just take a mono signal from the P12 to begin with.
So rather than using the separate outputs of Layer A & Layer B, splitting them, then summing them in the pedal, just place stereo feeds directly from your pedals into your mixer or take mono feeds from the Layers to your volume pedals.

Well, maybe your unhelpfulness will turn out to be helpful. Lets find out together. Are you saying that none of my questions are truly answerable? If so, then i should rephrase. Before i do that though i hope my intention with the questions are clear. Im not trying to figure out the exact amount of noise, and im not expecting people to know what my preference of "allott of noise" is. Im interessted in the thoughts, experiences and assumptions of you guys. If the scenario was this:

"I have a jack cable which is 100 000 meters long. I connect one end to my guitar and the other end to an amplifier. Will there be allott of noise?"

The answer would probably be yes, because for most people wanting to play guitar the amount of noise this would add would be above what they consider tolerable. If someone answered this question with "That depends on how you define allott of noise" they would be missing the point of the question. They are gramatically and philosophically correct, but contextually incorrect. The context is:

"A synth player wants to play synths. He has some ideas for a setup. He wants to minimize the amount of noise added by the chain of cables and devices between the synth and the speakers. He wants to keep the signal generated in the synth as close to the original as possible before its transmitted through the speakers. He wants to accomplish this without taking away any of the volume pedals".
Does this make sense?

Regarding your comment about stereo and mono. Im not turning stereo into mono at any point in the chain. I take the Left channel of both layers and putting them into a splitter to sum them so that they can be outputted from the Left output of the stereo volume pedal. The same goes for the Right channels. So the sum of the output from the third volume pedal will be "A and B Left" which comes out of the left output of the volume pedal, and "A and B Right" which comes out of the right output of the volume pedal. So the stereo image of both synths should be intact right? Im by no means proficient with this kinda stuff, but in both cases left is still left and right is still right, just summed with the other layers left and right.

And thank you for answering and spending time on this :) Peace and Love <3

Re: Using a volume pedal on the main output
« Reply #4 on: November 29, 2018, 12:33:35 AM »
The simple answer to your question is that the more things you have between the output of the instrument and the input for the engineer the more potential for the sound to degrade.  How much it degrades depends upon the quality of the equipment and your ability to manage engineering principles which lessen noise during your performance (generally keeping outputs high and inputs low).  The same setup can sound clean or really noisy depending upon how it is managed. 

Three pedals is a lot to manage during a performance.  You can accomplish the same thing with two pedals and probably with better control.  Also, one less pedal and two less cords equals less noise. 

Why do you want the four outputs going to the engineer?  The engineer hears what the mix sounds like in the house.  You don't. What you hear in whatever monitoring system you use may sound completely different than what it sounds like in the house.  At that point, you have to put some trust that the engineer will get what you are trying to do right. 

Hope that helps.

Jim Thorburn .  Toys-  Dave Smith: Prophet 08;
Pro 2; Prophet 12; EastWest Orchestral soft synths; Yamaha S-90; Yamaha Montage 8, Yamaha DX-7; KARP Odyssey; Ensoniq ESQ-1.  All run through a Sonar DAW with a Tascam DM-24 board.

Re: Using a volume pedal on the main output
« Reply #5 on: November 29, 2018, 09:41:11 AM »
Sorry Tarjeijazz, I always assume everyone has more tech knowledge that me as I only learn info pertinent to my projects. Several decades ago I was a close friend of Michael Gerzon - the Father of Ambisonics and so much more. We both understood that to move sounds around in 3 dimensions would require 4 speakers placed at the apexes of a regular Tetrahedron. He understood the details like phase relationships and all the maths, but I had a basic grasp of what was required.
 It wasn't until I bought Cassandra (my P12) that I was able to put any of this into practice. I bought Cassandra to further my research into what is now called 'Linear FM synthesis" (and because both my DX7s were broken), but I realised when she arrived that I had 4 output channels which could run a Tetrahedral array.

I have written very few voices that fully conform to the ideal for 3D movement of sound because they use up too many modulation options and so do not give me the range of timbres that I am more interested in. Here is a basic set up -
Voice parts A and B are stacked. Select a Timbre achievable with 2 oscillators and make 4 copies :- Voice A oscs 1+2, Voice A oscs 3+4, Voice B oscs 1+2, Voice B oscs 3+4.
You could probably use 4 mono volume pedals plugged into Voice A Left output, Voice A Right output, Voice B Left output and Voice B Right output. And by using 4 pedals move the sound between 4 speakers.
I use 2 Stereo volume pedals and pan Left or Right using expression controls and the Modulation matrix but effectively I am still moving the sound between 4 speakers, and If the speakers are placed appropriately I am moving the sound in 3 dimensions instead of the one dimension of sound movement from stereo.

Most of my 250 voice pairs on Cassandra do not implement full spatial sound because I used up all the slots in the Mod matrix creating maximised ranges of timbre for each pair of voices (A+B).

I have not checked up recently on the speed of electricity v the speed of sound, but it seems obvious to me that if the cables between the synth and the speakers are not all very nearly the same length, then the resulting sounds will be sent from different speakers fractions of a second out of step with each other and will arrive at a listener out of phase which would affect the quality of the sound. Not something that would bother a rock audience, but would of affected the recordings I made in 8 ancient churches.

I don't have a special tech buddy, but I read online that adding output channels together with a splitter can compromise equipment that isn't specially protected. I seem to remember that it also said splitting an output signal into 2 could cause noise as the signal strength is reduced. I chose not to bother DSI with a technical question as I have alternatives to splitters by using a multitrack recorder.

Gomjab

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Re: Using a volume pedal on the main output
« Reply #6 on: November 29, 2018, 08:37:35 PM »

Just one comment on cable lengths.  You are correct in that the distance from each speaker in your quad arrangement to listener is important as small changes can be a audible as difference in phase.  That is because sound waves leaving the speaker travel at 344 m/s at sea level. The electrical signals out of your Prophet however are traveling at closer to the speed of light 300,000,000 m/s so you would need a run of cable so long that resistive losses and impedance issues would be the gremlin long before phase effects.



Sorry Tarjeijazz, I always assume everyone has more tech knowledge that me as I only learn info pertinent to my projects. Several decades ago I was a close friend of Michael Gerzon - the Father of Ambisonics and so much more. We both understood that to move sounds around in 3 dimensions would require 4 speakers placed at the apexes of a regular Tetrahedron. He understood the details like phase relationships and all the maths, but I had a basic grasp of what was required.
 It wasn't until I bought Cassandra (my P12) that I was able to put any of this into practice. I bought Cassandra to further my research into what is now called 'Linear FM synthesis" (and because both my DX7s were broken), but I realised when she arrived that I had 4 output channels which could run a Tetrahedral array.

I have written very few voices that fully conform to the ideal for 3D movement of sound because they use up too many modulation options and so do not give me the range of timbres that I am more interested in. Here is a basic set up -
Voice parts A and B are stacked. Select a Timbre achievable with 2 oscillators and make 4 copies :- Voice A oscs 1+2, Voice A oscs 3+4, Voice B oscs 1+2, Voice B oscs 3+4.
You could probably use 4 mono volume pedals plugged into Voice A Left output, Voice A Right output, Voice B Left output and Voice B Right output. And by using 4 pedals move the sound between 4 speakers.
I use 2 Stereo volume pedals and pan Left or Right using expression controls and the Modulation matrix but effectively I am still moving the sound between 4 speakers, and If the speakers are placed appropriately I am moving the sound in 3 dimensions instead of the one dimension of sound movement from stereo.

Most of my 250 voice pairs on Cassandra do not implement full spatial sound because I used up all the slots in the Mod matrix creating maximised ranges of timbre for each pair of voices (A+B).

I have not checked up recently on the speed of electricity v the speed of sound, but it seems obvious to me that if the cables between the synth and the speakers are not all very nearly the same length, then the resulting sounds will be sent from different speakers fractions of a second out of step with each other and will arrive at a listener out of phase which would affect the quality of the sound. Not something that would bother a rock audience, but would of affected the recordings I made in 8 ancient churches.

I don't have a special tech buddy, but I read online that adding output channels together with a splitter can compromise equipment that isn't specially protected. I seem to remember that it also said splitting an output signal into 2 could cause noise as the signal strength is reduced. I chose not to bother DSI with a technical question as I have alternatives to splitters by using a multitrack recorder.

Re: Using a volume pedal on the main output
« Reply #7 on: November 30, 2018, 01:47:21 AM »
Thanks Gomjab. Michael Gerzon died years ago, but his work was very precise, and they still use his algorithms in sound processing equipment. I will stop considering small differences in cable length as relevant now, it was probably part of a specific theoretical model.

Re: Using a volume pedal on the main output
« Reply #8 on: November 30, 2018, 10:37:22 AM »
If ultimately the sound is going to be heard in stereo and not through a quadraphonic system, then your efforts to retain the quadraphonic elements by treating it as 4 mono signals are pointless.
Just treat it as 2 stereo signals and save yourself the hassle. 😎





Re: Using a volume pedal on the main output
« Reply #9 on: November 30, 2018, 05:04:57 PM »
Of course it is possible that if you heard a quadraphonic live improvisation on a Prophet 12 in a church built over 1200 years ago you might have a different opinion. Different strokes I guess.

Re: Using a volume pedal on the main output
« Reply #10 on: November 30, 2018, 10:00:53 PM »
The way I understand it, he wants to keep the stereo signal for each output but independently control the volume of each stereo signal with pedals.  Then the combined signal goes through a master volume control.  Complex, but a reasonable setup.
Jim Thorburn .  Toys-  Dave Smith: Prophet 08;
Pro 2; Prophet 12; EastWest Orchestral soft synths; Yamaha S-90; Yamaha Montage 8, Yamaha DX-7; KARP Odyssey; Ensoniq ESQ-1.  All run through a Sonar DAW with a Tascam DM-24 board.

Re: Using a volume pedal on the main output
« Reply #11 on: December 01, 2018, 04:15:40 AM »
The way I understand it, he wants to keep the stereo signal for each output but independently control the volume of each stereo signal with pedals.  Then the combined signal goes through a master volume control.  Complex, but a reasonable setup.

Yes! That is precisely what i want!

Individual stereo volume control for both layers, and a master volume for both layers in the same chain that keeps the stereo for bogh layers.

I coooould get a 2 midipedals to controll the voice volumes via NRPN per layer.....maybe i should look into that actually.....but i guess they are more expensive.

Re: Using a volume pedal on the main output
« Reply #12 on: December 01, 2018, 06:16:45 AM »
That's a fairly complex setup you have there.
 As a player myself, I'd say that is all good.
 As an audio tech I'd say: I would prefer separate DI signals from each synth. You are summing different timbres that need to be EQ'd and compressed by the FOH audio tech. You will achieve a better FOH sound if you allow the FOH tech look after this for you.
 I would run all my syth signals into their own volume pedals and then into a rack mounted-multi-input DI box. The sound team can then XLR out into the snake head all separated signals at the correct impedance. 
 Cheers.

Re: Using a volume pedal on the main output
« Reply #13 on: December 01, 2018, 06:18:52 AM »
#######One more thing!!!
 Don't use a "Y" cable to sum the signal!!!!
 Just noticed this on your original post. You can damage the P12 this way.

Re: Using a volume pedal on the main output
« Reply #14 on: December 01, 2018, 08:44:51 AM »
I took it as he has a four input pedal.  If the pedal only has two inputs, then a 4:2 sub-mixer would be in order.  I don't think the Y cable would damage the P-12, but would certainly compromise the sound.
Jim Thorburn .  Toys-  Dave Smith: Prophet 08;
Pro 2; Prophet 12; EastWest Orchestral soft synths; Yamaha S-90; Yamaha Montage 8, Yamaha DX-7; KARP Odyssey; Ensoniq ESQ-1.  All run through a Sonar DAW with a Tascam DM-24 board.

Re: Using a volume pedal on the main output
« Reply #15 on: December 01, 2018, 09:15:38 AM »
I'll expand on an earlier thought.  I have performed on stage thousands of times.  One of the things I learned is that the more complex the setup, the more chance for failure- either by equipment failure or human error.  Over time, I would cut back on anything that make the set up simple and reliable.  Over the years, my setup became more and more simple based upon that principle.  Doing so made my setup more reliable, and my performances improved too.

Your three pedal setup will be difficult to manage during performance.  When you are using both P-12 outputs, you will have to balance and simultaneously set the master volume.  Three pedals, two feet.  There is a way to make this more simple.  Take one output through a volume pedal (then to the master pedal) and the second output directly to the master pedal.  Your goal is going to be balance and overall volume.  Using your master pedal, you can get the overall, and one output in place.  The second "intermediate" pedal would then be used for balance of the signals.  Will be much faster to get your balance and overall volume this way.

The only way this setup does not work is if you intend alternatively manually swell and diminish each signal with the pedals  - kind of like using the pedals to create a manual LFO on the VCA for each output.  The two pedal setup will not work in that case.

Also, you will need to make sure that the VCA is set up so that the output with the intermediate volume control can always overpower the output connected directly to the master.   That way, you'll always have enough output to balance with the "unpedaled" output.

Just some thoughts from many years in the trenches.
Jim Thorburn .  Toys-  Dave Smith: Prophet 08;
Pro 2; Prophet 12; EastWest Orchestral soft synths; Yamaha S-90; Yamaha Montage 8, Yamaha DX-7; KARP Odyssey; Ensoniq ESQ-1.  All run through a Sonar DAW with a Tascam DM-24 board.

Re: Using a volume pedal on the main output
« Reply #16 on: December 02, 2018, 07:11:53 AM »
Without some form of resistance in the cable, you can definitely damage your P12 outputs summing with a Y cable. (20 year experience Audio tech speaking)
  There is nothing preventing the signal from one channel pushing current into the other channel.
 When summing you need to ensure that current can only go one way.
 Goodluck!


Re: Using a volume pedal on the main output
« Reply #17 on: December 02, 2018, 07:14:47 AM »