Skip to product information
1 of 3

Helios Channel Strip Racked Pair (Pre/Comp/Eq)

Helios Channel Strip Racked Pair (Pre/Comp/Eq)

Brand: Helios

Regular price £6,000.00 GBP
Regular price Sale price £6,000.00 GBP
Sale Sold out
Shipping calculated at checkout.

Sorry it's gone. We may have another in stock or on the way. Please enquire below (or check our weekly Gear Update for incoming rarities).

A pair of incredibly rare custom Helios channel strips (mic pre/eq/comp) built for Capitol Radio. Only a handful of these channels are knows to exist and this one of only three pairs to be racked and offered for sale.

Make An Enquiry
View full details

Product Description

Restored and racked by one of the designers of the original Focusrite Forte console at Master Rock in London. They have added independently switchable +48V phantom power. Like all Helios modules these are designed to produce an unbalanced output. This has been balanced using high-quality transformers, and an output attenuator allows the preamp to be driven hard if you wish.

History and Specification:

Capital Radio in London was a Helios customer from the early 1970s. They had at least one large-format Helios console, as well as a number of small ‘emergency warning mixers’ that were installed at remote locations around the city in case the Thames Barrier failed!

In 1979 Capital wanted to refit their studios in the Euston Tower, and commissioned Helios to build new mixers. Unfortunately, Helios went out of business soon after starting work on the project. To recoup their costs, Capital sent their engineers to the Helios factory to salvage as many parts as they could, including these mic input channels. Capital then asked Tweed Audio to build a new Master Control Room console that incorporated the Helios modules. This was completed in late 1981 and decommissioned in 1997 when Capital moved out of the Euston Tower premises.

All Helios desks were custom-made to the buyer’s specification, so no two are the same. These modules have the classic Helios mic preamp circuit with the Sowter 3374 input transformer, but they also have several unique features:

* They are the only known Helios mic channels with a built-in compressor — a very versatile and good-sounding design based around the dbx 202 VCA chip. Attack, release and ratio are continuously variable and threshold is controlled by adjusting the preamp gain. It’s possible to achieve massive amounts of gain reduction if you want! The compressor can also be switched pre or post EQ.

* Nearly all Helios modules use 24V and 0V power rails, but these run off +18V and -18V. This means they have more headroom and can drive a line-level output without an additional gain stage.

* The EQ design is similar to that found in so-called ‘Type 78’ and ‘Type 79’ Helios modules, but the outer bands are shelving rather than peaking. All controls are continuously adjustable including the low- and high-pass filter cutoff, and they use centre-tapped pots so the centre position really is ‘zero’.

* These modules have Sowter 3374 transformers. Helios used Lustraphone in the early modules, then switched to Beyer, and finally to Sowter. They are a lot better than the Beyer transformers by all accounts.

BROKERAGE SALE - photos are from the seller. If you have questions about this item please get in touch and we will pass them to the seller.

Brokerage Sale Information:

This is a brokerage sale by Soundgas on behalf of the owner. The item is not at Soundgas and we have (sadly) not had a chance to use it ourselves. As such, we can offer no guarantee on this item beyond the 14 days you have to assess it. However, we only work in this way with trusted clients who really understand their gear. That said, it is the buyer's responsibility to confirm details provided in the listing by the seller are to their satisfaction - if you have any questions at all please let us know before we arrange shipping.

As a brokerage sale, payment will be made to us but will be held in escrow for the seller until the buyer confirms satisfactory receipt of the item. The buyer has 14 days from receipt to raise any concerns, after which we will release funds to the seller. Full terms available on request.


In excellent cosmetic condition. See photos for more information on cosmetic condition.

Voltage Information

Switchable voltage for use anywhere in the world - it will be set up ready for you to use before we ship.


Zero rated for VAT.

Customer Reviews

Be the first to write a review