IGS Audio Alter 500 Classic FET compressor

The ALTER 500 is a FET compressor built in the 500 standard. The FET-type solution was used for the first its application in the legendary UREI 1176 compressor from the 70s. The ALTER is a single-channel unit with stepped input and output controls. The Ratio switch has six positions, including two additional to the original 1176 1:1 and 2:1 settings. Slam Mode can be turned on with a separate switch, working regardless of the Ratio settings. Attack and release times can be set to Fast / Mid / Slow with 3-pole switches.

The compressor is equipped with a relay bypass switch on the front panel. The input is balanced with a modern, low-noise op-amp and the output with a Carnhill transformer. The circuit has two amp stages, between which is the output control. The stage amps are based on the discrete 990 circuit. The level of gain reduction is shown by a 20 point led bar.

DEVICE TYPE
Fet Compressor: Yes
BASIC FEATURES
All stepped manipulators: Yes
INPUT & OUTPUT
Input Impedance (balanced): 10k ohm
Output Impedance (balanced): 600 ohm, Carnhill transformer
Audio transformers: Yes, Carnhill
LEVELS
Operating Level: +4 dBu
Max input level: +20 dBu
Max output level: +22 dBu
Noise Level: -99 dBA
Max. gain: 36 dB
Max Gain Reduction: 20 dB
TIME CONSTANTS
Attack: 20us, 400us, 800us
Ratio: 1:1 to 20:1
Release: 50ms, 600ms, 1.1s
BANDWIDTH
Frequency response: 8 Hz to 20 kHz, +/- 0.1dB
DISTORTION (@ 20 HZ - 20 KHZ)
THD+N: 0.012%
POWER
Power consumption: 2.5W
PACKING BOX
Shipping weight: 1kg

US and EU parcels ship via UPS, ETA 1-7 working days from pickup day zero. That also applies to most locations worldwide.

All shipments are fully insured.

Bigger shipments requiring pallets or custom made crates ship to US, CA, JP, CN, AU and other outside of EU locations via DHL Air Freight, ETA is normally approx. 7-14 working days from pickup day zero.

Big shipments inside EU ship via different freight companies, recently mostly via ACE Logistics. Freight forwarders can use different courier companies for deliveries to final destinations.

Palletising and crating time can vary depending on the size of the shipment and packaging queue. We pack all our shipments with great care.

You are most welcome to pick your order up yourself from our Retrosonic Pro Audio showroom, studio and warehouse in Tallinn, Estonia.

We ship worldwide – contact us for a personal shipping quote or any other questions.

VAT (Value Added Tax) can be deducted if you have a company with a valid EU VAT number or if you're based outside of the EU. Non-EU buyers pay all and any import tax and duty as regulated by their local customs.