• Portable single audio channel isolating transformer
• Earth lift switch on input
• Unique centre tap switch for connecting transformer core to different ground circuits
• Ideal for reducing noise at outside broadcasts and events
• Very high quality Lundahl audio transformer
• Very good line balance
• Excellent Common Mode Rejection
• Robust lightweight aluminium chassis

The Glensound External Transformer (ET) range was designed to help a specific outside broadcast customer who was having no luck in curing hum problems with cheap DI boxes. This customer was providing audio facilities in a venue away from the OB truck and there was sometimes hum being received at the OB truck on his output circuits. The input circuits of a professional audio device should of course be able to handle this situation but as our customer was a freelance contractor for the OB company he wasn't in the situation that he could tell his employer that their multi million pound OB truck had a rubbish audio desk. Our solution was to design a transformer isolating unit starting with a very good quality audio transformer from Lundal and adding a unique feature of a variable centre tap switch.

The unique centre tap switch allows the transformers' centre tap to be connected to either the devices' input ground, output ground or isolated from both. This switch alongside the use of the Lundhal transformer solved our customers' problems.

Although originally designed for use at the output end of an audio circuit the ET range can of course be used to reduce problems at the input end of the circuit as well.

Currently the range consists of single channel, dual channel & four channel rugged portable boxes, please contact us if you would like a 1RU rack or more channels in a portable unit as the modular nature of the design allows us to do this easily. 

clip point > +28dBu into 150R

Noise (A weighted 20Hz -22KHz) 300R Termination -117dBu (in all switch conditions)

Input impedance 4.8k

Output impedance 106R

Insertion loss < 0.2dB @ 1kHz (100k load)

THD @ 1kHz +4dBu = < 0.02%

Please use one of the following methods to contact us:

Telephone: 01622 753662
International: +44 1622 753662
Email: sales@glensound.com
Skype: live:marc_8167
Online: contact form