Deacy Amp

‘Queen’ bassist John Deacon’s legendary Deacy Amp:

Deacy Amp recording 'Another World' sessions Feb 1998

Deacy Amp in ‘Another World’ recording sessions Feb 1998

Deacy Amp sinewave at Dave Petersen's place August 1998

Deacy Amp sinewave assymetric clipping: Dave Petersen visited us in August 1998 and put his signal generator into the Deacy Amp showing us how the amp clips in a very assymetric way, undoubtedly one of many important reasons why the Deacy Amp sounds so unique

A not so serious moment at Nigel's mate Chris otherwise known as 'the educated man' at Newport. March 2007 as we were on the long hunt for the Deacy's mysteries

Deacy boffins hard at work: a not-so-serious moment at Nigel’s mate Chris’ place at Newport UK March 2007. We were on the long hunt after the Deacy’s mysteries.  Chris, otherwise known as ‘the educated man’ is giving me the ‘v-sign’ rabbit ears….thanks a lot Chris.

The Educated Man twiddles some knobs March 2007

The Educated Man twiddles some knobs March 2007



My phone call ‘interview’ with John Deacon in July 1998:

John was a very nice fellow to talk to and gave his account about finding the Deacy Amp circuit board and then what happened with putting the amp together and using it as a practice amp, and then taking the amp to band practice with Freddie, Brian and Roger.

By the way, John Deacon did not tell me that he changed the Deacy Amp’s front end – this came from something that Brian had told me during 1998 at Allerton Hill when we began pulling apart and examining the Deacy Amp. Brian said that he thought they had changed something in the amp to help it cope better with the signal coming in from the treble booster. Whether this happened or not I cannot say, and when I asked Brian again about this in 2007 he laughed and told me that he couldn’t remember. In the piece I wrote for Brian’s website about the Deacy Amp, yes I made this up based on what Brian had said, and I took the old newspaper adage: ‘print the legend’

In the phone call with John I asked him if he had ever made Brian a treble booster in those early days of Queen, because for many years it has been reported that he had. John told me that he had not made a treble booster for Brian.

From my notes on the phone call with John Deacon 22nd July 1998:

John said that he found the amplifier section in the back of a skip which was sitting on the side of the street in London, and that he noticed the wires dangling over the edge of the skip and picked it up before it was thrown out. John said that he was studying for a degree in Electronics at the time and was always tinkering with electronic bits and pieces, and that the circuit board looked interesting to him when he first saw it. He thought that the transistor amplifier might have come from a cassette player or a radio. John thought at the time that he might possibly use it as a small practice amplifier – he played guitar as well as bass. John thought that this had happened in about 1972 and that he was already playing with Brian at this time.

John said he already owned the hi-fi bookshelf speaker box which he then modified so that it housed the amplifier circuit board inside with no controls at all on the outside of the box. John liked the simplicity of only having a jack socket to plug into with the amp’s volume set internally at full, although he said that initially he probably had a volume control hanging on the outside somewhere. The amp had a warm and pleasant sound although John said that it was always partly distorted and would never sound clean.

John told me that through some chance he showed the amp one day to Brian when he  brought the amp along to band practice, and said Brian was immediately interested in the amp’s possibilities especially when he used his Red Special guitar and treble booster with it. John said that with the Red Special and treble booster, the little amp offered a pleasant pretty type of saturated distortion which was utterly unique and very different to the ‘cutting harder sawtooth transistor distortion’ found in many effect pedals and amps of the time.

John remembered that the sound engineers who they worked with liked the way the little  amp behaved in the recording studio where it would produce a ‘consistent response’ as he termed it, whereas the engineers found it more difficult to capture on tape the excitement and dynamic live sound of Brian’s Vox AC30 amps. However John quickly mentioned that all the work and discussions with sound engineers was never his area of interest, and therefore he was never privy to detailed information in this area.

When I asked John about whether he had made a treble booster for Brian at this time in the early/mid 1970s, he told me that he had not.


Origins of the Deacy Amp circuit:

Dave Doughty, Mitch and the other good folks at finally revealed that the Deacy Amp pcb is from a Supersonic PR80 portable radio.

Interestingly, John Deacon had originally told me in 1998 that the circuit might be from ‘ a cassette player or radio’ so it looks like he was right all along.

Manuel Angelini in 2014 located an original and very similar, if not identical circuit board to the Deacy Amp’s Supersonic PR80, and has done extensive research on the Supersonic factory and the Supersonic PR80 origins.

See Manuel’s youtube clip:

Manuel’s website:


History of the Deacy Amp replica 1998-2011:

What began as a fun part time project kicked off by myself, Pete Malandrone and Brian May in the middle of 1998 (initially with technical help from Dave Petersen) has finally come to fruition in March 2011 after an journey of many twists and turns.

Nigel Knight came on board to offer his technical expertise in 2003 and eventually took on the R&D task completely in early 2008 when after developing several prototypes, we sat down with Brian and Pete and decided to start again with a clean sheet. This meant Nigel re-examining the original Deacy amp to the nth degree – previously we all had been very reluctant to take apart several fragile areas because of the danger to this irreplaceable amp (for more on the whole journey from 1998 to 2011 please see my Deacy booklet piece below in red).

Since January 2008 there has been great effort from Nigel Knight in order to get this innocuous looking little amplifier produced and brought into being. Almost everything in this amplifier has had to be custom made especially for it and usually at great expense, and this has involved a large time and money commitment from Nigel.

Several people involved in the project have contributed articles to the Deacy Amp booklet – this part below in red is from my article:

Background of the Legendary Deacy Amp and the development of the replica by Greg Fryer:

In July 1998 John Deacon related to me the circumstances surrounding his putting together of this unique sounding amplifier and speaker cabinet.

John literally found the circuit board as he was walking down the street one day in London – this occurred in early-mid 1972 when he was first playing in “Queen” with Freddie Mercury, Roger Taylor and Brian May. Being a keen electronics experimenter (John was then studying for an electronics degree), his attention was drawn to the wires that were dangling over the side of a builder’s skip which was filled with rubbish and about to be taken away to the tip.

These wires were attached to a circuit board and John’s curiosity led him to examine the board to see if he could salvage it and put it to some use. He initially thought that the circuit board might have come from a battery operated cassette player or radio, and after inspecting it further decided it would do the job as a small practice amplifier for guitar (John played guitar as well as bass).

John coupled the newly found circuit board with a spare bookshelf speaker cabinet which he had lying around – the circuit board was fixed inside with two screws and the finished product featured no controls whatsoever. On the back panel of the cabinet was fitted a single jack socket to plug the guitar lead into – the amp’s power was turned on by simply connecting the two battery clips which came out from the back panel to a large 9 Volt PP9 battery.

With a standard guitar plugged in, John said the amp possessed a warm and pleasant if partly distorted sound, but lacked brilliance or much definition. However a new way of using this little amp was about to be found that would change its sound and make it an invaluable part of Queen’s recording armoury.

On one occasion John brought his practice amplifier along to band rehearsal and showed it to Brian. Immediately Brian was interested in the amp’s possibilities once he heard how it behaved when he plugged in  his innovative home made Red Special guitar and his single transistor treble booster pedal. Using the guitar and treble booster together changed the amp’s sound dramatically, overdriving both the input and output stages and producing a richly distorted yet defined and sustained sound which resembled such things as violins, cellos and even vocals.

John commented that the rich saturated compressed type of distortion produced by the combination of Red Special guitar, treble booster and Deacy Amp was very unique and was different to the harder sounding distortion common at the time in many guitar effects and amps.  He mentioned that the recording engineers that the band were working with particularly liked the way the little amp behaved in the studio. Here the amp would produce a consistent response John said, whereas the engineers found it more difficult to capture on tape the exciting and dynamic sound of Brian’s Vox AC30 amps.

John’s small amplifier became known as the “Deacy Amp” and featured regularly on Queen albums where Brian used it for his creative, highly original multi-tracked guitar orchestrations. These were painstakingly built up line by line (and even note by note on some of the more complex pieces such as “Good Company” from Night At The Opera). Although the Deacy Amp is a deceptively simple looking piece of equipment, the wide number of creative sounds that Brian has managed to coax from it over the years belies the outwardly simple appearance.

Brian has described the way that the Deacy Amp’s sounds sit and blend together when recorded as being “symphonic”, whereas when the AC30 was tried for the layered sounds it didn’t have the same character and effect in the way the notes blended together. The tracks “Procession” and “The Fairy Feller’s Master Stroke” from the 1974 album “Queen II” saw the first recorded examples on a Queen album of the Deacy amp.

Perhaps the best known example of the amp’s use is on “God Save The Queen” from 1975’s “A Night At The Opera”, whilst possibly the most unusual use was for all of the jazz band sounds on the song “Good Company” (trombones, clarinets and all!) from “A Night At The Opera”.

The Legendary Deacy Amp continues to this day in good health and continues to occupy an important place in Brian May’s recording studio.

Making of the Deacy Amp replica:

During the early months of 1998 as Brian May was completing the recording of the “Another World” album at his London Allerton Hill studio;  Brian, Pete Malandrone and I discussed the idea of making a replica of his  Deacy Amp. For some time Brian and Pete had been aware of the need to have a good quality replica as a backup for Brian’s own use in case anything ever went wrong with his original amp. Due to the great interest shown over the years in the Deacy amp we also thought it was worthwhile to start the process of examining the original amp so that we could possibly one day offer replica amps for sale.

At that point we had little idea of the amount of work that might be involved, how long it might take and how much it might cost, or who we might have to find as partners to be able to bring the project into physical reality and have amps eventually manufactured. As the project began I asked assistance initially from two friends in London and Sydney who were experienced guitar and amp repairers:  Dave Petersen and Colin Bloxsom.

In July 1998 Dave Petersen and I built 3 replica amps which were assembled in Brian’s Allerton Hill studio, and after I returned home to Australia in late 1998 Colin Bloxsom worked with me on further development of the Deacy amp design. When Colin left to go overseas I then asked Nigel Knight if he would like to be involved in the Deacy development project.

I would personally like to thank these three gentlemen for their invaluable technical assistance, and in  particular Nigel Knight. Without Nigel’s specialist electronic expertise and dogged determination to see the job through to the finish, the Deacy Amp replica would not have come about.  I would also like to thank very much Brian May and Pete Malandrone who have always been very encouraging during the development of various Deacy Amp prototypes and have always been extremely generous with both access to the original amp and with their time during the years of development.

The first 3 replica amps that Dave and I built during July/August 1998 took a fair bit of guesswork regarding the driver and output stages. Plotting out the basic circuit was fairly straightforward but there were areas that kept on being an intriguing mystery until Brian finally gave the go-ahead to take everything apart in January 2008. Because of the fragile and delicate nature of these areas of the original amp (mainly the transformers and some circuitry immediately adjacent to the transformers), we were extremely reluctant to take the amp completely apart due to the risk of doing irrepairable damage. Dave assured us that the Deacy’s transformers were none that he had seen before and were not available commercially. Brian and Pete didn’t want to wind up with a non functioning Deacy Amp and I certainly didn’t want to be remembered as the man who killed the Deacy Amp!  So we agreed to take educated guesses for the transformers (based at first on the old Mullard reference manual and advice from transformer manufacturers), and pinned our hopes that through trial and error we would eventually get the sound correct. There were some surprises and frustrations in store for us….

The speakers were also a critical part of the Deacy sound, and I tested many speakers for these first 3 amps in 1998. Fortunately we managed to find a very good sounding twin cone English made Eurotec 6.5″ speaker, and it was by far the closest sounding to the original Deacy amp’s English made Elac twin cone speaker. These 3 Mk I replica amps sounded surprisingly good in their own right although it was clear to us that there was still much work to do to achieve an identical sounding replica Deacy amp.

Back in Australia in late 1998, I continued the development work with Colin Bloxsom in Sydney and we asked specialist transformer companies to make new experimental coupling and output transformers which were to be wound to different specifications and in various lamination sizes and styles. We also experimented with several circuit variations. Throughout 1999-2001 we made the Mk II and Mk III version amps which sounded closer again to Brian’s original Deacy and its elusive tonal and distortion characteristics.

In 2003 I asked Nigel Knight if he would like to become involved with the Deacy replica project, and he brought to the table his specialist knowledge of “Deacy era” 1950s-1970s transistor and valve electronics as well as his keen interest in Brian’s Red Special guitar. Over the next 4-5 years several prototype amps were built and modified whenever spare time was available, and we both had a lot of fun producing new versions of the amp and trying to crack the Deacy’s tonal mysteries. During this time we continued to refine the transformer specifications, trial new speakers and refine the overall circuit. In both 2005 and 2007 I visited London with prototype amps to show Brian and Pete (amongst other things like Red Special and AC30 stuff), and to make further examinations scope tests and A/B test recordings of the original Deacy amp. In the 2003-2007 amps we sometimes used a Phillipine made Dai Ichi twin cone speaker which was strong in some sonic areas that the Eurotec wasn’t. By 2007 Nigel and I had gone about as far as we could go based on our still incomplete knowledge of the Deacy’s transformers and circuit, and we were also in need of a speaker that would sound identical to the tonality, focus and volume of the original Elac. As good as our previous Eurotec and Dai Ichi speakers had been, they were just not the same as the old Elac so it was clear that we would have to take the extra step of finding a speaker company that was capable of producing a custom made replica of the Elac 6.5″ twin cone speaker, and who was also willing to commit the considerable R&D time towards achieving this.

In January 2008 Brian, Pete and Nigel got together to discuss the Deacy Amp prototype’s future, and to our great delight Brian decided that it was now time to take apart whatever needed to be taken apart from the original Deacy in order to be able to produce an identical sounding amp. Nigel then took on the task of conducting this vital final research work and also began the process of looking for suitable speaker manufacturers who could duplicate the Elac speaker, plus a host of other things.

To be able to produce a replica amp many issues needed to be solved including having custom made  grillecloth screenprinted to the exact pattern of the faded original Deacy grillecloth, having custom mahogany veneered chipboard manufactured so that we could then manufacture speaker cabinets that were comprised of the same materials as the original amp, having our stocks of germanium transistors put through an involved and expensive process to make them RoHS compliant, plus a list of other things. Not the least issue to solve was the arduous development of the speaker, and fortunately due to Brian’s long association with Celestion they very kindly agreed to come on board and develop a special replica speaker for our amp. During the 2 1/2 year development process Celestion produced for us over 40 different specification prototype speakers, an astonishing display of their total commitment to the task.  Without the development of this Celestion speaker, the final Deacy replica amp would not have sounded correct in all its tonality and detail, so we therefore owe a great deal of thanks to our esteemed partner in this project Celestion!

Well its been a long and often amazing journey, and there have been many times when we have wondered if we would ever see the finishing line. From the very first times I heard the Deacy Amp on the “Queen II” and “Sheer Heart Attack” albums, to me it sounded like an inspired piece of equipment which produced inspired music, nothing like I’d ever heard before and almost “other worldly” and magical in its unique tones and the wonderful passages produced. I am still inspired when I hear those and later Deacy Amp pieces and I sincerely hope that our Deacy Amp replica will be enjoyed by a great many people and will help those people in making their own inspired music.

Best wishes,

Greg Fryer


The KAT Deacy Amp Replica can be bought from Nigel Knight’s website at:

It is beautifully made with fine attention to detail.

Deacy Amp replica

Deacy Amp replica