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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Audio Measurement and Testing => Topic started by: Ben Pierce on August 20, 2018, 01:17:12 pm

Title: Multi output tone generator
Post by: Ben Pierce on August 20, 2018, 01:17:12 pm
Hey everyone. I'm new to the forums. I work for an audio electronics company. I am trying to find or build a tone generator for testing audio consoles and audio over Ethernet. What I need is something that can send a tone to 64 XLR input channels simultaneously. I'd prefer if it wasn't a computer-based solution because computer audio can glitch and pop which could affect my testing results. My idea is a piece of gear that has one or more analog tone generators that can be fed to DB25 connectors. Does anyone have any advice on how I could do this? Sonifex has an 8 channel unit but it's too pricey. 
Title: Re: Multi output tone generator
Post by: Scott Holtzman on August 20, 2018, 01:33:27 pm
Hey everyone. I'm new to the forums. I work for an audio electronics company. I am trying to find or build a tone generator for testing audio consoles and audio over Ethernet. What I need is something that can send a tone to 64 XLR input channels simultaneously. I'd prefer if it wasn't a computer-based solution because computer audio can glitch and pop which could affect my testing results. My idea is a piece of gear that has one or more analog tone generators that can be fed to DB25 connectors. Does anyone have any advice on how I could do this? Sonifex has an 8 channel unit but it's too pricey.

Royce has a $200 8 channel distribution amp that is flat and virtually unmeasurable THD.

Title: Re: Multi output tone generator
Post by: Ben Pierce on August 20, 2018, 02:52:50 pm
Ok. Something like that could work. It's definitely going in the right direction. So would there be any downside to say running a tone generator into one main distribution amp, then send the 8 outputs to 8 other distribution amps? That way I could have 64 channels.
Title: Re: Multi output tone generator
Post by: Scott Holtzman on August 20, 2018, 06:39:41 pm
Ok. Something like that could work. It's definitely going in the right direction. So would there be any downside to say running a tone generator into one main distribution amp, then send the 8 outputs to 8 other distribution amps? That way I could have 64 channels.

Rolls RA163.  Input impedance is probably high enough just to parallel the inputs.  You could daisy chain 9 of them if you wish.

 
Title: Re: Multi output tone generator
Post by: Riley Casey on August 21, 2018, 10:05:27 am
Simplest way to get a lot of mic level outputs on XLRs would be to secure a few passive press mult boxes and drive them with your tone generator du jour.  Even a phone app tone generator would work although you might want a single four output distribution amp to drive the mults.
Title: Re: Multi output tone generator
Post by: Erik Jerde on August 21, 2018, 11:49:24 am
Hey everyone. I'm new to the forums. I work for an audio electronics company. I am trying to find or build a tone generator for testing audio consoles and audio over Ethernet. What I need is something that can send a tone to 64 XLR input channels simultaneously. I'd prefer if it wasn't a computer-based solution because computer audio can glitch and pop which could affect my testing results. My idea is a piece of gear that has one or more analog tone generators that can be fed to DB25 connectors. Does anyone have any advice on how I could do this? Sonifex has an 8 channel unit but it's too pricey.

Do you have any concerns about using the exact same signal on all outputs?  If you end up summing those signals down the line and thereís been any relative delay youíll end up with comb filtering.
Title: Re: Multi output tone generator
Post by: Ben Pierce on August 21, 2018, 05:01:17 pm
Do you have any concerns about using the exact same signal on all outputs?  If you end up summing those signals down the line and thereís been any relative delay youíll end up with comb filtering.

Yes. This is something that could be an issue. I will be using it to test mixers, so it needs to have the same level of input to every channel at the same time.
Title: Re: Multi output tone generator
Post by: Mac Kerr on August 21, 2018, 05:03:51 pm
Do you have any concerns about using the exact same signal on all outputs?  If you end up summing those signals down the line and thereís been any relative delay youíll end up with comb filtering.

Unless you are cascading digital devices that will each add latency, where would this different latency come from?

Analog DAs or passive resistive splits will not introduce any latency.

Mac
Title: Re: Multi output tone generator
Post by: Ben Pierce on August 22, 2018, 09:42:32 am
Unless you are cascading digital devices that will each add latency, where would this different latency come from?

Analog DAs or passive resistive splits will not introduce any latency.

Mac

I would prefer an analog setup for this reason. I have a digital solution but it would mean cascading digital mixers.
Title: Re: Multi output tone generator
Post by: Erik Jerde on August 22, 2018, 10:57:36 pm
Unless you are cascading digital devices that will each add latency, where would this different latency come from?

Analog DAs or passive resistive splits will not introduce any latency.

Mac

Could come from all sorts of places on a digital desk.  Just bussing a channel together with another one thatís got some inserts can do it.  Assuming itís a console that doesnít do delay compensation of course.  I donít know exactly how OP is planning to use his setup so I was just making sure he was aware of this possibility.