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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 => Wireless and Communications => Topic started by: Miguel Dahl on January 02, 2020, 01:26:58 pm

Title: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Miguel Dahl on January 02, 2020, 01:26:58 pm
I just need to ask, as I'm a bit unsure of this.

We have racks containing 4x G3 500 and 1x ASA 1 in each rack.

We also have an older G2 rack with 4x receivers and 1x ASA 3000.

The ASA 1 are on the antenna-input BNCs outputting a DC-voltage to drive active antennas. If I use the ASA 3000 as a "main distro", is this unit fine seeing the voltage which ASA 1 BNC antenna-inputs is feeding into the ASA 3000s outputs? It's 12V 120mA. The user manual for the ASA3000 does not state if those outputs are protected against incoming DC.

I must say that I have done this before without thinking about this issue. Twice. Last time the setup sat powered up for over a month this way, feeding the 4x channels of G2 and 24x channels of G3 divided in six racks containing 4x G3 units and 1x ASA 1 in each rack.
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Christian Ekren on January 02, 2020, 03:12:56 pm
A theatre I've designed at for a couple seasons runs this exact setup. Have never had issues feeding the ASA1 from the ASA3000 outputs. I don't have schematics but would presume there is some type of DC-blocking capacitor/circuitry on the ASA3000 outputs. We were running about 64 channels of G2/G3 receivers fed from a pair of helical antennas.
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Jean-Pierre Coetzee on January 03, 2020, 02:13:58 am
If in doubt add a DC blocking adapter. Can't remember who exactly makes but I'm sure you will find something on mini-circuits or something that someone has linked to in this forum before.
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Miguel Dahl on January 28, 2020, 01:24:00 pm
One more question regarding this.

First (so there's no misunderstaning from my first post). The 3000 unit is now a "standalone" unit, it does not feed the G2-rack any longer, so all outputs A1-8 and B1-8 are available now.


We run our standard setup with the racks made like one of the options from Sennheiser: We have 1x ASA 1 in each rack feeding 4x receivers. Alright. But. When using two racks we don't use a splitter for those two racks: We run them as per Sennheiser: Antenna 1 into rack 1, Antenna 2 into rack 2. Then using the "out A" from each rack into "Antenna B in" on the other rack. So both racks will get both antennas. But rack-wise it's not 1:1 from the 3000 distro.

This means that if using the 3000 splitter, we can use only output A1 and output B1, to feed 8 channels with RF.

So with simple multiplication this would mean that if we do this all the way, one output from the 3000 feeding one ASA 1 in each rack with 4 receivers, could actually drive 64 receivers. This seems to me excessive. One pretty simple setup feeding 64 channels? Is there something I'm not aware of here?
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Henry Cohen on January 28, 2020, 02:45:11 pm
We run our standard setup with the racks made like one of the options from Sennheiser: We have 1x ASA 1 in each rack feeding 4x receivers. Alright. But. When using two racks we don't use a splitter for those two racks: We run them as per Sennheiser: Antenna 1 into rack 1, Antenna 2 into rack 2. Then using the "out A" from each rack into "Antenna B in" on the other rack. So both racks will get both antennas. But rack-wise it's not 1:1 from the 3000 distro.

This means that if using the 3000 splitter, we can use only output A1 and output B1, to feed 8 channels with RF.

So with simple multiplication this would mean that if we do this all the way, one output from the 3000 feeding one ASA 1 in each rack with 4 receivers, could actually drive 64 receivers. This seems to me excessive. One pretty simple setup feeding 64 channels? Is there something I'm not aware of here?

Excessive? Not if you're running 60+ receiver chassis. The caveat here is increased system noise when cascading multicouplers, and in this case the ASA's are not the quietest of designs.
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Miguel Dahl on January 28, 2020, 03:40:18 pm
Excessive? Not if you're running 60+ receiver chassis. The caveat here is increased system noise when cascading multicouplers, and in this case the ASA's are not the quietest of designs.

Thanks. But my reasoning is not wrong? I understand the noise. But I haven't tried this myself, nor do we have the channels in house to do it. But theoretically (and IRL) this is possible? We're running 4 receivers in each rack.. Maybe you meant something like that? I our little rental sphere we've never done anything more than 28 channels. 64 will never ever happen.
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Henry Cohen on January 28, 2020, 03:47:27 pm
Thanks. But my reasoning is not wrong? I understand the noise. But I haven't tried this myself, nor do we have the channels in house to do it. But theoretically (and IRL) this is possible? We're running 4 receivers in each rack.. Maybe you meant something like that? I our little rental sphere we've never done anything more than 28 channels. 64 will never ever happen.

You asked if the capability was excessive. It's excessive if you never need to run anywhere close 64 channels. It's not excessive if you do operate near that count.

I would probably opt for using one ASA-1, connected to four receivers, per ASA-3000 output pair. That's 32 channels and less noise added for one side of each receiver.
Title: Re: Is Sennheiser ASA3000 fine with getting ASA 1 DC voltage into its outputs?
Post by: Miguel Dahl on January 28, 2020, 03:51:32 pm
You asked if the capability was excessive. It's excessive if you never need to run anywhere close 64 channels. It's not excessive if you do operate near that count.

I would probably opt for using one ASA-1, connected to four receivers, per ASA-3000 output pair. That's 32 channels and less noise added for one side of each receiver.

Right, I get your point, no "out A into B-link", just do them 1:1.