In part 1 of a series of three videos about making a replica of Brian May’s legendary Deacy amplifier, I briefly discuss the origins of the Deacy amp circuit (salvaged from a vintage transistor radio that John Deacon found in a London dumpster in 1971) and what Queen tracks Brian used it to record on. I then move on to talk about the new Knight Audio Technologies (KAT) amplifier board kit and the other component parts required including suitable vintage and modern woofer and tweeter loudspeakers and the cabinet itself. I finish by introducing the only official Deacy amplifier replica which was made by Knight Audio Technologies between 2011 and 2019.
The annual meet-up for enthusiasts of Brian May’s music and equipment was once again held at Theale Village Hall near Reading in Berkshire, U.K. on Saturday, 8th October 2021. The organiser, Jon Underhill, assisted by several other co-ordinators this year helped grow the event by increasing the numbers attending and stage-managing a series of talks and demonstrations. These included Martin Pitcher covering Brian’s Starlicks set-up, talks by Arielle and Queen’s Sound Engineer Justin Shirley-Smith and a 25th birthday present by Andy Guyton to Luke Timmins of his Guyton Time Warp Red Special. A raffle for some superb donated items including a KAT BM Mini Rig and a KAT Groundbreaker raised £530 for the Save Me trust. Click the link below to see additional content on the events section:
Red Special Meet-up TVH 2021
In late 2020, I was offered the opportunity to acquire a Brian May style live rig originally built for Andy Barnett by Nigel Knight of Knight Audio Technologies (KAT). The rig was contained in an SKB roto-molded 6U shallow rack case (model 1SKB-R6S) and consisted of the following 19″ rack units:
- Dunlop DCR-2SR CryBaby Wah Wah (1)
- TC Electronic G-Major 2 guitar effects processor (1)
- Sennheiser wireless receivers (2)
- Custom made KAT audio routing and MIDI switching master controller (1)
- Custom made KAT wireless receiver switcher (1)
- Canford power supply unit (1)
The rig was designed to work with a custom made KAT 24 way floor switching unit with amplifier muting and MIDI/effect pedals switching features. Also included was a KAT RED-18 strap mounted treble booster and all ancillary items including two Sennheiser EW 500 G2 bodypack transmitters and various heavy duty professional cables (some custom made) to connect all the units.
I bought a second G-Major 2 unit from a U.K. eBay seller for £150 as a spare in case the supplied unit developed an unrepairable defect in the future. To house the units, I ordered a custom made shock-mounted 19″ rack flight case with removable front and rear covers and top lid with a wheeled trolley from NSP Cases (The Flight Case Company) in the U.K. The YouTube video below covers the unboxing, assembly, connection and demonstration of the rig. Also featured in the video are my home made Brian May Red Special replica, a KAT Deacy replica amp and a 2001 model Vox AC30 TBX amplifier.
For the 100th distinct web page on dsgb.net and the 50th site blog post, I have published an article on one of the perennial topics of conversation in Brian May enthusiast circles: treble boosters:
I cover some background information and restrict the discussion to three treble booster variants related to Brian May and Queen, the current 3-in-1 BMG Treble Booster Classic unit developed by Nigel Knight of Knight Audio Technologies for retail by Brian May Guitars, Brian’s KAT RED-18 strap-mounted treble booster and the Fryer Sound colour series (TB Touring, TB Plus, TB Super and TB Deluxe). There are embedded videos from Jamie Humphries demonstrating the Fryer treble boosters for Guitar Interactive and Frank Campese demonstrating the 70s setting of the BMG TB Classic.
Check out the third article in the musical equipment section of this website which covers the Brian May Deacy Amp replica made by Knight Audio Technologies (KAT):
It contains the original pictures shown below, technical specifications for the amplifier, hyperlinks and four embedded YouTube videos, including Jamie Humphries‘ review for Guitar Interactive magazine and some demonstrations recorded by Martin Pitcher at the 2018 and 2019 Brian May Red Special enthusiast meets.
The new Groundbreaker from Knight Audio Technologies (KAT) is a fully transformer-coupled ground (earth) isolating interface that eliminates unwanted hum and noise caused by system ground loops. It is suitable for studio and live environments and is configured to accept both balanced and unbalanced signals. If your amplifier is exhibiting ground loop hum, simply connect a Groundbreaker to the amp’s input via a patch cable then connect the output of your effects chain, delay, chorus or treble booster pedal to the input of the unit.
Although similar products have been available (e.g. from Mike Hill Services) for some time, this unit is priced competitively at £64.50 recognising that multiple units will be required to fully eliminate ground loop hum depending on the configuration of the guitar rig. If you have read my other blog posts highlighting new and forthcoming KAT products then you will already appreciate that every KAT product is backed by Nigel Knight’s expertise as an electronics designer and many years of experience building and maintaining equipment for Brian May of Queen. This product works well in one, two and three amplifier outfits or when connecting mains powered effects (e.g. a Boss CE-1 Stereo Chorus pedal); eight examples of which are illustrated in the diagrams below.
- 1/4″ TRS (tip, ring and sleeve) input and output jacks allow for balanced or un-balanced signals
- High impedance input to maintain signal clarity
- Fully passive, requires no power source
- Uses bespoke mu-metal shielded high quality transformer for sonic transparency
- Housed in a rugged solid steel enclosure
In his latest YouTube video, Nigel Knight (the guy who does Brian May’s electronic work) demonstrates how to assemble one of his excellent KAT treble booster Plush kits. The video is speeded up for the impatient amongst us. It is a must watch for any electronics enthusiasts who are also into Brian May gear.
The KAT treble booster Plush kit can be obtained direct from KAT (Knight Audio Technologies) at £49.50:
Information from Nigel’s website:
“This is a full kit of parts that will enable an electronics beginner to build a very high quality KAT treble booster. The components provided are the best for the job in-hand. They are the same components used for the builds of many KAT treble boosters and Fryer Sound TB Touring, Deluxe and Plus. The circuit board has been specially designed for the kit so that the build can be easy with all components identified on the board. The case is the same powder-coated, silk-screened folded steel unit used for the TB Touring, Deluxe and Plus, so rugged, durable and yet, attractive.
Sound-wise, this treble booster has been developed to emulate the 1980s era of Brian May’s tone with approximately 33 dB of gain, so think Queen from the late 70s through to the end. Think Wembley… Think Live Aid!
So, what’s in the kit?
Well, everything you need to successfully build the TB except for a few hand tools and a battery.”
Following up on the recent story of the KAT Studio-One all-valve practice amplifier, Nigel Knight has released details of the other part of his R&D endeavour over the past few years. Nigel recently announced:
Brian was never happy that we had to discontinue the production of the Deacy Amp replica, but the decision to do so was based purely on the fact that we could no longer source transistors with the correct characteristics that matched the original, either locally or globally and certainly not in the numbers we needed to extend production. So from the point that Deacy Amp replica serial number 0150 rolled out the door, I was on a bit of a mission to design its replacement.
This then, is the Studio-D. It is germanium Deacy’s silicon brother if you will. After years of trawling through transistor specifications, we finally found a set that could be configured to provide the same responses as the original AC125, AC126 and AC128 transistors. We are still using the original Deacy circuit, transformers and components albeit with the odd bias-tweak here and there and it still fires into a single 6.5″ twin-cone speaker. The resulting amplifier sounds magnificent and we’re really pleased with it.
The Studio-D is equipped with an adjustable battery simulator (DABS Unit), HF tone trim pot (that mimics the tone dulling effect of putting a tea-towel over the amplifier) and a built-in attenuator that has been optimised to the speaker and Deacy responses and, like the Studio-One, allows you to dial-down the volume.
Nigel Knight recently revealed a prototype 1 W (max), all-valve 2 x 6.5″ bedroom/studio combo amplifier. The styling and overall cosmetic appearance pays homage to the legendary Vox AC30 used by Brian May.
The valves (vacuum tubes) are biased such that at each stage, the grid starts to go positive at exactly the same point that a Vox AC30 would at full volume.
The KAT Studio-One guitar amplifier features:
• Two newly developed KAT DSP 6.5 TC speakers which have an on-board filter network that tailors the frequency response to give the full bodied mids of Brian’s Deacy amplifer but without the high frequency fizz audible in many 6.5″ twin-cone drivers.
• A built-in attenuator that has been developed in-line with the speakers to ensure the same tone is produced at all output levels. -24 dB attenuation brings it down to almost whisper level whilst still producing jangly cleans and smooth full-on distortion.
• Plywood cabinet construction.
Nigel has deployed all his electronics design expertise and experience producing and maintaining Brian May’s gear to offer the holy grail that amateur Queen players have been seeking for some years: the full on Wembley ’86 tone in your home, or Project BMIB (Brian May in your Bedroom) as I’m calling it. [Other Vox AC30 + Deacy amplifier emulation BMIB solutions are available, such as the Fryer Guitars Mayday effects pedal.]
Nigel has recorded a short demonstration video in the link below using a KAT STB Stomper and Retro Sonic chorus pedal. The amplifier is still at the prototype stage and is not available for general sale yet. Note that corner protectors have been made but are not fitted to the prototype illustrated in these three images (photo credit Nigel Knight).
Update as of 25 September 2022. I recently bought three units and have released a brief (6m 43s) YouTube video in which I unbox them and show you around the inside and outside as well as a quick demonstration through my KAT Brian May rig. Please also check out my gear page for this amplifier here:
Knight Audio Technologies (KAT) has developed a “drop-in” speaker upgrade for the popular, discontinued Vox VBM-1 Brian May Special amplifier. It costs £35.00 + shipping direct.
An alternative upgrade option which some people have carried out involves buying a Dai Ichi brand DC65-30 speaker (still available from Wagner Online in Australia at the time of writing) and fitting a 390 microH 1.3A ELC16B radial inductor (choke), RS part no. 6755576 and a 2.2 microF capacitor, RS part no. 7270473.
However, this original option is ultimately more expensive and involves soldering. Check out the product on the KAT website and view the straightforward installation video on Nigel’s YouTube channel.
Text from the KAT website:
“This is a brand new speaker/filter combination enabling VBM-1 users and Deacy Amplifier-style project builders to get their amps closer in tone to the real Deacy Amp.
The KAT DSP 6.5 TC has been developed primarily as a replacement for the Celestion G6 unit that is sadly no longer in production. It has an on-board filter network that tailors the frequency response to give the full-bodied mid range tones of the real Deacy but without the HF ‘fizz’ that seems to dominate most 6.5″ twin-cone drivers.
A by-product of this development was the realisation that this unit could be dropped straight into the Vox VBM-1 giving immediate results. The Vox VBM-1 is a great amplifier, but, it is a little let-down by its stock speaker unit that tends to suck-out the precious mid range tones and enhance the unwanted high frequency ‘fizz’. The KAT DSP 6.5 TC is a straight swap-out with the stock VBM-1 unit with no soldering required to undertake the works. Just 11 screws and 6 minutes will have the works completed and the tone of the amplifier improved many-fold!
The KAT DSP 6.5 TC can also be used in your own Deacy amplifier-style projects to give your amplifier that great Deacy ‘honk’!”