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• Tips on Acoustics for Your Home Studio
• Frequently Asked Questions from Voice Talent
• Tips on ISDN, 2 3
• Tips on Wiring Your Home Studio, 2 3 4
• Tips on Selecting and Using a Microphone

General Tips on Usage

• ISDN is a digital phone line which is connected to other ISDN phones lines all over the world by dialing the far end number --- just like making a standard phone call. Since ISDN has two "bearer" channels, you usually dial two numbers to make the connection. Each number you dial makes a guaranteed connection capable of transferring 64 kilobits per second of data so you end up with a data call capable of 128kbps.
• Even though there are two numbers on each line, ISDN uses only one phone line compatible with standard CAT3 phone wiring that already exists in your home. Installers will connect your ISDN line on an RJ45 jack but you may use standard RJ11 connectors, lines and adapters if you wish.
• ISDN data connections send audio both ways so you can send your mic to ProComm and hear direction from the producer.
• Bi-direction audio has nothing to do with dialing two numbers. An ISDN session with only one number dialed is still bi-directional. Audio bandwidth is increased with the second call.
• Most ISDN codecs are capable of transmitting and receiving on several different compression algorithms. Common ones are AAC, MPEG Layer II, MPEG Layer III, G.722 and G.711. High fidelity algorithms are AAC MPEG Layer II and MPEG Layer III while G.722 and G.711 are used mainly for low delay communication.
• There is an inherent delay when you work with an ISDN connection. Usually, if the codec you are using is a hardware based unit and running MPEG Layer II, you can expect a quarter-second delay both ways.
• ProComm has adopted MPEG Layer II, mono at 128kbps as a standard for receiving audio from voice talent. This was chosen for its inherently low transcoding loss.
• ISDN does not directly interface with the Internet. There are codecs which work over IP (the data transmission protocol which underpins the Internet). ISDN does not operate over the Internet and cannot talk to boxes that do. The only way to "connect" with someone using an IP codec is to have someone who has both types "bridge" the connection by patching the two together. There are some boxes, however, that will operate in both realms like the software based AudioTX and hardware based Musicam NetStar.
• Availability of ISDN is quickly becoming scarce. When ISDN was first deployed, one of it's uses was for connection to the Internet. As faster and faster competitive technologies became more intrenched, ISDN was left behind.