On the Bench: Projects & Prep

Despite the lockdown, I’m still working in my little workshop at Brighton Electric, making progress with new arrivals & projects that have been on the back burner:


Moog MKPE & Moog MKG

Recapped & upgraded power supply. The two units are constructed in the same way and have similar power supplies

Moog MKPE internal shot

Moog MKPE internal shot

Moog MKPE eq board showing pots

Moog MKPE eq board showing pots


TC Electronic 1220 preamp / equaliser

TC Electronic 1220 eq board with pots

TC Electronic 1220 input / output board before recapping


CBS Audimax 4450 stereo compressor

CBS Audimax 4450 compressor board 4450 – deep 1U box with lots of seperate circuit boards

CBS Audimax 4450 internal shot shows power supply, control board plus left & right compressor boards. The grey encapsulated units are proprietary CBS timing modules

CBS Audimax 4450 compressor board

CBS Audimax 4450 control board & power supply before recapping

CBS Audimax 4450 front panel preset pots – to be replaced with regular pots & knobs

On the bench: CBS Audimax 4450 Stereo Compressor / Leveller

The Audimax range was developed by CBS for AM & FM radio broadcasting. It’s a compressor / leveller designed to create a consistent level from mixed sources and less-than professional operators. But it can be creatively abused to dramatic effect: ” I noticed that excessive input creates huge compression density and also makes these things pump like mad!”

The Audimax was often paired with a CBS Volumax limiter which was used to drive the radio transmitter to peak modulation – but not over. Overmodulated transmitters could cause interference in other bands and the FCC levied hefty fines for offenders

At the time broadcasters vied for the loudest signal in their area and there was a constant struggle to achieve the loudest, punchiest signal. The Audimax and Volumax – dubbed “The Max Brothers” – were the CBS way of achieving this

Levellers like the 4450 use a slow release time to avoid pumping. Later models, like this one, had an internal three-way switch to select release times. I’ve modified this to have much more aggressive release times to accentuate the effect

Attack times were set by the CBS compression module, an encapsulated “secret” module developed by their engineers. Schematics are now available

There’s a fair amount of background info available for these:




CBS Audimax 4450 compressor board 4450 – deep 1U box with lots of separate circuit boards

CBS Audimax 4450 internal shot shows power supply, control board plus left & right compressor boards. The grey encapsulated units are proprietary CBS timing modules

CBS Audimax 4450 compressor board

CBS Audimax 4450 control board & power supply before recapping

CBS Audimax 4450 front panel preset pots – to be replaced with regular pots & knobs

On the bench: UREI LA4 Compressors

I’ve just finished refurbishing a tidy pair of LA4 compressors. They are late-model silver-face LA4s with the chrome UREI badge so the same kind of age as the 1176 Rev G & H and 1178 stereo compressor

I fitted a new set of incandescent meter bulbs so they give that classic UREI orangey glow when powered up

They’ve been recapped with bigger reservoir caps in the power supply and higher-value bipolar caps in the audio path. They’ve been aligned in standalone and stereo-linked modes and will come with a stereo link cable and a set of new XLR pigtails




On the bench: Altec 1519A & 1612A Preamp Limiters

Two Altec limiters have been on the bench recently for testing & refurbishment. I’ve recapped & modified both units and am hugely impressed with them – they’ve really exceeded my expectations

They seem to be typical of 70s industrial / installation gear with terminal strip i/o, balancing transformers and plugin preamps to match sources. I think a lot were installed in schools, churches & etc and were setup then left alone. They have two inputs – nominally one mic and one line input which are mixed together – and a switchable output limiter

Altec 1591A on the bench for a recap

Altec 1591A audio board before recapping

On the bench: Orban 414A Compressor

This Orban 414A is in exceptional condition and refurbishing it has been something of a labour of love. We’ve rebuilt & recapped the power supply and switched it to 220 Volt via an internal jumper. The electrolytics in the audio path have been replaced with Panasonic bipolar caps and the original incandescent bulbs replaced with white LEDs, dimmed down so they’re not too bright. The back panel had the option for XLR connectors so we’ve fitted Neutrik XLRs wired in parallel with the original barrier strip. This means no pigtails are needed to hook the compressor up…

The whole process took far longer than planned but it’s a great-sounding compressor, beautifully made in the 1980s, and I think it deserves to be brought back to peak performance

Orban 414A in the shop

Orban 414A back panel XLR mounting holes

Orban 414A meters

Orban 414A power supply

Orban 414A meters

Orban 414A label

On the bench: dbx 160X Compressors

dbx 160X stereo pair with sequential serial numbers

dbx 160X stereo pair with sequential serial numbers

I am working through a delivery of ten dbx 160Xs from the USA. They have been refurbished with new UK power plugs (Euro plugs available on request), pots & switches cleaned and metering aligned. All are in good shape with just a few knob caps required to make them spot-on. As usual with vintage kit they have age-related marks and are not cosmetically perfect

I have made up three stereo pairs – one pair with sequential serial numbers, one with close serial numbers and a third pair which are selected to match age & condition. Links below

On the bench: Valley International 440 Compressor

I have another great Valley compressor in for a 220 voltage swop & power supply recap. Just arrived from the USA, it’s in really tidy condition. These compressors sound amazing – if you’ve never owned one, I can recommend any Valley unit as the ultimate antidote to boring compressors

When it’s ready you’ll find it here. Email if you need more info

Valley 440 on the workbench

Valley 440 on the workbench

On the bench: Orban 622B

Orban 622B

I’ve just taken delivery of a really tidy Orban 622B equaliser. These are great, useable 4-band equalisers with per-band bypass switches like a Klein & Hummel. The example has all-original knobs & switches and looks like it’s been tucked away in a box for the last thirty years

I’ll be refurbishing this with new caps, upgraded power supply and replacement of the troublesome Tantalum caps with electrolytics. When it’s ready it’ll be listed here. Update soon!

On the bench: Yellowhammer

Yellowhammer is a distortion box designed for studio use. It’s at second prototype stage and is being road-tested by a number of producers & engineers

It’s a passive device which uses transformers, diodes, inductors & capacitors to generate distortion & filter the results. All the controls interact, making it a little unpredictable, but it’s easy to navigate once you start using it

The next prototype will be a rackmount version though I think there may be demand for a freestanding unit like this one

For more information or to arrange a demo, email yellowhammer@bn1studio.co.uk 

To hear the Yellowhammer in action, upload your sound samples via WeTransfer to upload@bn1studio.co.uk and we’ll run them through the Yellowhammer

Yellowhammer prototype 2 Sketchup drawing
Top panel layout & drilling template
Input XLRs & transformers being test-fitted
The green-fading-to-yellow paintjob didn’t pass inspection
First set of knobs, before lettering
New knobs & lettering in place – now ready for testing

On the bench: Symetrix 501

This pair of Symetric 501 compressors has just arrived from the USA. They will be tested, switched to 220 VAC and recapped before being listed in the shop

These are great-sounding VCA compressors with a big reputation. They have a switchable sidechain, switchable auto attack/release, stereo link switch and a separate limiter

The 501 came in a couple of versions: early models used the TA-101 VCA – designed by Paul Buff of Valley People fame – whilst later models used a dbx 2181 VCA. I have one of each in stock

On the bench: TC Electronic 1220 Stereo Equaliser / Preamplifier

I’ve just finished recapping & testing this TC equaliser / preamp. It’s a useful, musical-sounding eq with a decent amount (20 dB) of gain in hand. Each channel has two bands of EQ, ±20 dB gain control & bypass switch

This 1220 is in nice condition and still has all the original knobs & switches. It’s in the shop now

TC Electronic 1220

This has the usual TC Electronic upside-down PCB

TC Electronic 1220

Simple EQ section with no electrolytic capacitors

TC Electronic 1220

Power supply and input / output on one board, recapped with Panasonic caps, bipolar for the audio section. PSU bypass caps are on the other side of the board

On the bench: McMartin LR1004C Limiter / Compressor

This McMartin LR1004C Limiter / Compressor came from a radio station in the USA and dates back to the 1970s. The limiter is based on a diode bridge, like the Neve 2254, and the compressor is switchable. Both sections sound awesome when crushing drum tracks – sound samples to follow

I’ve recapped the unit & will replace the power transformer so it can be used on 220 Volts. The attack & release pots are inaccessible so I’ll move them to the front panel & source some suitable knobs

Note the lovely horizontal meter – proper meters like these are an endangered species now and have become diabolically expensive

The LR1004C will be in the shop when ready

Under the hood

McMartin LR1004C Limiter / Compressor

Guts shot

McMartin LR1004C Limiter / Compressor

70s orange plastic compressor in/out rocker switch

McMartin LR1004C Limiter / Compressor

Matching power switch

McMartin LR1004C Limiter / Compressor

Neve-style horizontal meter shows GR or output level

McMartin LR1004C Limiter / Compressor

Compressor board and line output board

McMartin LR1004C Limiter / Compressor

Lots of space for attack & release pots to be added

Audio test files

Drum room test audio file processed through Alesis Micro Limiter and a modified Alesis Micro Limiter

This test is anything but definitive: levels have not been matched and it’s extremely hard to match settings on these units

Original file

File through modified Alesis Microlimiter

File through unmodified Alesis Microlimiter

Modifications, Upgrades & Recapping


We do a number of modifications including a high-pass filter mod for the Cloud CX335. Email workshop@bn1studio.co.uk for details

Recently-modified gear includes


We can recap most pieces of gear. Equipment done to date includes:


We can sometimes source output transformers for dbx compressors. We can supply dbx 160X or dbx 160XT compressors with the transformer fitted or retrofit a transformer to your dbx. Email workshop@bn1studio.co.uk for details

In Preparation

We have quite a list of gear in prep. When it’s complete it will be for sale in the shop. Till then you can fin it on our In Prep page

Inputs & Outputs

When mixing you need outboard gear, lots & lots of outboard gear!  That means lots & lots of inputs & outputs if you’re mixing “In The Box”

Having looked at the cost of SSL Alphalink interfaces the plan looks something like this:

  • Buy a couple of ADA8000s
  • Rework the power supplies
  • Bypass the preamps
  • Fit high quality input caps
  • Remove the rear panel XLRs
  • Blank off the front & rear panels
  • Fit 25-pin D connectors for audio ins & outs
  • Connect to Fireface 800 via ADAT cables
  • Sync via Word Clock from Fireface 800

Before diving into the good ADA8000 I bought locally (thanks, Phil), I bought a broken one on eBay and disassembled it to work out how to proceed.  There’s lots of info online about the ADA8000 but much of it is inconclusive