Frequently Asked Questions - ASPEN


The SPNConference has a powerful new echo canceller that can handle echo cancellation for multiple incoming signals from the far side. You can have multiple codecs and a phone line coming in and bridge all of them together. You will need to assign a minimum of four signal buses (or mixes) for conferencing. We suggest the following protocol. Setting up the AEC signal routing. Conferencing requires a minimum of four mixes. Two are dedicated to the AEC itself. These are called the AEC Reference mix and the AEC Signal mix. You will need to assign two mix buses in the ASPEN units for these two mixes. We recommend you use mix bus 48 for the AEC Reference and Mix bus 47 for the AEC Signal. The third is the SEND Mix (AEC Out) – you will need to assign a bus for each outbound signal. For example – if you have just a telephone line, you will need one SEND mix for the Tel. If you have one phone and two Codecs, then you will need three Send mixes, one for the telephone and one for each of the codecs. We recommend you use the mix buses 46, 45, 44 etc for these signal mixes.

This will keep all your conferencing mixes close together and separate from your local amplification mixes. Finally, you will need your LOCAL mixes – these are the signals which will be sent to your local amplifiers and may be shared with microphones. How many of these you need is dependent on the number of amplifier channels you have in use. Reference Mix – should carry ONLY the incoming signals from the far side. That would be signals from the telephone, and codecs – the inbound part of any two way communications line. DO NOT put any microphones or local line level sources (such as multimedia inputs) on this mix. AEC Signal mix – should have ONLY the local microphones. No multi-media sources, no line level inputs – microphones only. AEC Out Mix(es) – Will SEND the output of the AEC (which is the echo cancelled microphones), plus any multi-media sources to the fars side. If you want to have a bridged conference system, you will have the codec incoming going to the telephone SEND mix and the telephone going to the codec SEND mix. BE CAREFUL HERE! Make certain that you do not accidentally route the incoming telephone signal BACK on the outgoing telephone SEND mix! Or Codec to codec, etc! Local Mixes – this brings the audio from the far sides and the microphones into the room – note that we are routing the incoming phone and codec signals to the same buses as the local microphones which then feed to the amplifiers.

ASPEN latency is 1.33ms for the SPN812 and 1.43ms for the SPN1624. As you stack additional units, you add only 125 microseconds per additional link (two RU units have 250 microseconds). The 1GB backbone upon which ASPEN Net runs keeps latency extremely low. 125 microseconds is equal to a mere 6 audio samples.

ASPEN is self organizing. You won't do anything. Once your rack is built and the units interconnected with the single Cat6E cable, the ASPEN units will organize themselves into the correct Master/Slave configuration automatically. The top unit will become the master and all the subsequent units will be slaves. If you add another unit to the stack, it will be added automatically in about 90 seconds. Because the 48 mix buses are bidirectional, whatever assignment you have made for the output mixes will remain correct regardless of position n the rack.

The only effect the sequence will have in your rack will be on the control side. You can control an entire multi-unit ASPEN system through a single RS232 port but it MUST be the RS232 on the Master unit. Commands to the slaves will be preceded with a numerical designator surrounded by square brackets so the stack of ASPEN units will know which command is for which unit. Example : [2]run(3) will run macro number 3 in the second unit in the rack. So, the position of the unit will be important when writing control code.

Single RU units such as the SPN16i and SPNConference will give you 15 logic inputs for buttons or 10K linear pots and 8 logic outs for LED"S or contact closure control. The two RU units such as SPN32i, SPN1624, SPN2412 and SPN1612 will give you double that amount (30 in, 16 out). Each logic input can be used for level control (of single or multiple I/O's), to execute macros, call up presets or invoke actions. The macro control language in the ASPEN series is powerful and allows you to build sophisticated control systems with simple, push button interfaces - take a look at the RCWPB8 as an example.

Don't overlook the possibility of using the RS232 port as a control port as well! The send string command in the macro language allows you to build control commands to be sent to other serial controlled devices in your system. With a single button, you can have the ASPEN system change levels, route signals to different speakers, dial the far side connection and lower your projector (and turn it on) - all through a single macro.

It Works...WELL! We built a proven signal path that preserves good gain structure, follows known good audio practices and yet gives you virtually unlimited routing capabilities with 48 mix buses that act independently of each other.

NO LIMITS - Every function is available full time, all the time. No limitations, no over-usage warnings, if you see it, you can use it.

SAVES TIME - Fast setup. No starting from scratch every time! It’s easy to configure and includes a powerful macro control language for everything. No Gas Gauge. No compiling.

EASY - Intuitive GUI takes you from start to finish including an easy one touch macro recorder.