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SOLD! Diamond Series Platinum booth for sale in Los Angeles 

I have a client in Los Angeles with a 3 Carat Diamond Platinum Series booth for sale.  This is the top of the line booth built by Vocalbooth, and it's spacious.  The booth is designed to sit in a corner of your room and takes up 6' of wall space on each side.   Ventilation and acoustic foam is included.  It is in good condition and must be picked up. We will assist with disassembly and moving out of the building to your provided truck.   We can move and re-assemble for an additional fee.  

Model dia-0013 3 Carat Diamond Platinum Series RETAIL PRICE $7195.00 

Asking $3700, but offers will be considered.  Cash only paid directly to owner.  

Please contact George for any questions.  



Can You Sling the ISDN/IP Lingo? by Dave Immer

Some acronyms and contractions have embedded themselves in our daily discussions of configuring, using and troubleshooting our live audio networks.

Here are some common ones in no particular order:

PSTN: Public Switched Telephone Network
ISDN: Integrated Services Digital Network
SPID: Service Profile IDentifier
CODEC: COder/DECoder
Telco: Telephone Company
TA: Terminal Adapter
IMUX: Inverse Multiplexer
kbps or kbs: Kilobits Per Second
BERT: Bit-Error Rate Test
LEC: Local Exchange Carrier
CIC: Carrier Identification Code
PIC: Primary Interexchange Carrier
CPE: Customer Premise Equipment
IP: Internet Protocol
QoS: Quality of Service
FEC: Forward Error Correction
SIP: Session Initiation Protocol

Let me know if there are other ones you encounter often.   Thanks,

-Dave                              Complete library of newsletters:


Troubleshooting Your ISDN Codec: Rear Access Is Key by Dave Immer

Equipment gets mounted and positioned based on access to user controls, meters and info screens – all on the front panels. I recommend planning for the likelihood of component failure somewhere in your system and your involvement in identifying and fixing it. Rear access is key.

When you need to troubleshoot your codec, especially older ISDN models, access to rear panel cables, connectors, switches and indicator lights is often essential. If you have your equipment mounted in a tight inflexible space it will surely make your troubleshooting, already a stressful prospect, even more difficult. Position racks away from the wall. Leave room to rotate a component on a shelf. Leave a little slack in the cables.

Plan your studio setup to allow for rear-access to equipment. Admittedly this requires more room. 

Let me know if you have  questions or comments about this.  Thanks,

-Dave Immer                      

 Complete library of newsletters:


Use Your ISDN Codec as a POTS Phone Patch by Dave Immer


New ISDN codecs and some legacy models can make and receive calls to and from standard POTS (Plain Old Telephone Service) telephones, and any phone available via the PSTN (Public Switched Telephone Network). Your ISDN line must be configured for Alternate Circuit Switched Data and Voice, which is what you typically get anyway.

It sounds as good if not better than standard POTS hybrid units such as Telos One or Gentner. And you will have the advantage of better metering and, in some units, digital i/o.

I have tested a handful of ISDN codecs that deliver a relatively clean POTS signal:
1. APT Tokyo & Equinox
2. Musicam Suprima & RoadWarrior
3. Telos Zephyr Xstream  & Classic

Other brands like TieLine and Mayah have the capability also.

Older models such as the CDQ Prima, PrimaLT, RoadRunner, APT Milano, 3D2 and DolbyFax do not have this capability, even if you do have a CSD/CSV enabled ISDN circuit.

But if your codec is able to initiate a call to a POTS phone, place the encoder in the G.711 mode and choose mu-law (µ-law) as the protocol (North America.) Some of the newer models auto-sense incoming Voice mode calls and adjust accordingly.

Let me know if you have questions or comments about a phone patch. Thanks,

Dave Immer,                                                             


Note from George:

I am always amazed how much better an ISDN codec works as a phone hybrid than even expensive digital hybrids like the Telos One.  I've mentioned this to Telos and they deny this function even exists!  Recently a client with a Telos Express (now discontinued) wanted to get a phone patch.  Since the Express has a built in mic preamp and mixer, it was a very simple process.  We plugged the monitor output of the Express into his USB audio interface, and a complete system was built with one cable.  


Boom! Zap! Lightning Strikes and Voltage Spikes by Dave Immer

If your ISDN line delivers a lightning-induced voltage spike to your codec, a few things might happen:

1. An easily replaceable fuse gets blown.
2. The software and programming get corrupted requiring a factory reset (cold boot.)
3. A major component gets fried, requiring factory service or replacement.

In addition to your AC-power lines, your ISDN line is vulnerable to lightning strikes and should pass through a surge protector before connecting to your valuable equipment.  Many people think that just using an AC-power surge protector is enough. But it’s the ISDN line itself that I’ve found to present a higher risk of damage.

A basic surge protector that includes phone or ethernet jacks will cost in the $50-$80 range and is worth it. They are available at hardware stores, Home Depot, etc. For a more robust system, check out I use the Tower Max CO/4-110 (this replaces the RJ-45 wall jack) and Tower Max 4 KSU for my lines.

The surge protection device will “sacrifice” itself should a strong enough voltage event occur. You will have to then replace the device – a bargain compared to replacing your codec. If your line seems to be dead, this event may have occurred. Test your line by plugging it directly in to the wall jack. If it works then that’s what happened.

If you don’t have surge protection  yet, you should unplug the ISDN cable from the codec when you’re not using it.