Search for the Ultimate Tone: Part Two

A three part series on my strive for a great guitar sound

Posted in Tone Gear Amplifiers Tubes

Search for the Ultimate Tone: Part Two - A three part series on my strive for a great guitar sound - by Simon Campbell

I have spent 35 years in search of the perfect guitar tone. This is the second in a series of three articles describing the journey to date and how I reached the conclusions about the gear and techniques I now employ. Grab a stiff whisky and let's examine the signal chain from the amplifier to recording console and / or PA.

[Editor's note: this article was written in November 2009 and I change my rig regularly. To find out where I am right now with video and audio content, I have created a new series of articles. Read part three and then part fourafter this one]

My sound may not be to everyone's taste but hopefully the following blurb will give you some ideas and pointers to develop your own unique tone learning from the tens of thousands of pounds I spent on getting here! Before you start, you may want to read the first one!

The sound you achieve is all about the way you play rather than the gear you use.

For those of you living the Isle of Man, I am giving a 'Tone Workshop' at Peter Norris Music on Sunday April 11, 2010 at 1900. I will be discussing and demonstrating all the stuff I talk about in these articles. If you fancy coming along book on the free workshop!


Well now we are in a whole can of worms. Amplifiers are more personal than haemorrhoids and every guitar player had different opinions and preferences.

Great players of all genres choose from the bewildering array of modern and vintage amps and, providing they are well set up, can all sound totally sensational.

I have had many, many amplifiers and will be featuring pictures and set-ups in my last edition of this series. The ones I can remember are:

Manufactured in the 60's

Manufactured in the 70's

Manufactured in the 80's

Experience of owning these amplifiers has given me a really good perspective on the subject. I am about to go into the studio again and will be using a selection of amps (specifically my 'Dumble' clones - see below - old Marshall's, Fender's and Vox) for the different soundscapes I want to achieve.


For years now I have really loved the Howard Dumble style amplifiers. Based on a Fender TwinReverb, they are very detailed and revealing, have an amazing 'clean' sound, and a 'touch sensitive' overdrive.

Here is a rare picture of of Howard. Courtesy of Jesse Schwarz, author of the Dumble Book, which every person interested in these amps should buy!

They are not for the faint hearted however, as you, and more disturbingly the audience, hears everything: cock-ups a speciality :-)

They usually feature one channel with a 'foot-switch-able' overdrive stage, tone defeat (removes the tone controls out of the circuit, thereby fattening the tone). Some feature a footswitchable FET (Field Effect Transistor), a jazz/rock switch and/or mid-boost.

Original Dumble's are vastly expensive and can go for $30,000 USD. They were made and 'tuned', by the man himself, for individual players and therefore the vary wildly in tone and style.

Dumble users are legion, but big names include: Carlos Santana, John Mayer, Robben Ford, Larry Carlton, Eric Johnson, Stevie Ray Vaughan, Ben Harper, Lowell George, Steve Lukather, Sonny Landreth, Jackson Browne, David Lindley, Dean Parks and Joe Bonnamassa.

As he doesn't make them any more, and the price is astronomical, many of these guys tour with clone units as do I!!!

The first 'clone' I bought was a TwoRock 100W 'Sapphire', followed quickly by a second one (they were a little unreliable).

I have recently bought a TwoRock 10th year Anniversary and have on order, a Van Weelden Twinkleland (strangely, the website has no pictures or indeed reference to the Twinkleland, but Google it and you will find many references as Bonamassa is using them) and a Bludotone Bludodrive. Robben Ford takes his amps to be serviced there; Larry Carlton and Matt Schofield are both using Bludodrive's...


A lot of tosh is talked about tubes (valves) but there is one thing that's certain, they make an enormous difference to the tone.

Messing with the tubes, specifically in the preamp and overdrive stages of the amp really makes a difference (usually tubes one and two) and tend to use NOS (New Old Stock) tubes from the 70's and 80's. These are very expensive but I feel they are worth it.

Experimentation to get the best tone has resulted in a combination of Telefunken, JAN-Phillips and GE 7025/12AX7 in positions one and two of the preamp stage.

I am currently using Winged-C output tubes (the people who took over the Svetlana factory in Russia) 6L6 matched by Watford Valves. They also do some NOS tubes, but they are becoming increasingly rare and hence expensive.

Again, listen and change them to suit your style.

Amplifier bias

Re-biasing is an adjustment of the voltage that is applied to the plates of the tube. Each set of tubes will draw different current and consequently the voltage applied to them needs to be adjusted when new tubes are fitted.

Some amplifiers come with LED that light we the bias is correct, some require metering, some are fixed bias and will need component changes to correctly bias the amplifier: correct bias will give you the best tone and I do own a bias meter.

Warning: Valve amps require very high voltages to work. When messing with the bias you will be inside the amp and could easily kill yourself. If you are not confident with this, use a qualified amplifier technician who knows what he is doing - some are total clowns.

Mains voltage and frequency

The mains voltage you apply to everything will effect the sound of your equipment. Most good quality effects power supplies and rack mount units will cope with some variation of mains input voltage; not so with valve amps as their power supplies are somewhat cruder.

A famous example of how this affects the tone is Eddie Van Halen. He used a 'variac' to lower the voltage going to his Marshall heads that helped create his unique 'brown sound'.

If your amp is sounding bad at a festival (with generators), in Europe or a remote village, check the mains voltage.

The USA use a mains frequency of 60Hz; the UK uses 50Hz. Some people tell me this makes a difference, I have to say, I haven't noticed it!

Speaker cables

Again, loads of bull here. Valve amps must have a load attached or they will blow up, simple. Also the cables mustn't be shorting out as this will also kill the amp. People tell you that using 'guitar cable' is bad for the amp, and this is is partially true, but for no more reason than the conductors in these cables are very thin; thin conductors have a high inherent resistance.

Resistance in speaker cables is bad and therefore cables should be thick (ie the two conductors to be in excess of 1.5mm), well terminated and as short as possible. I use Monster and Klotz speaker cables.

Echo and reverb effects

This is one of the keys to my stage tone. I really don't like digital delay going though my main amp; I feel it muddy's the sound. So, I take an output from 'effects send' of the amp into the input of a Bludotone Loop-a-Later and an output from this device back into the amplifiers 'effects return'.

But what the fuck is a Loop-a-lator? Let me explain. It's a device made by the very effusive Brandon Montgomery of Bludotone.

Most Howard Dumble and the associated 'clones' do not have a buffered effects loop. This causes problems when connecting them to external effects; levels and impedance mismatches cause sever 'tone suck' and strange problems. I do wonder why they are there at all if they don't work.

Anyway, old Dumble got around this, making more money in the process, by creating a device known as a Dumbleator. This inserts a 12AX7 (ECC83) tube buffer into the loop and sorts the problem out. It has input and output volumes plus bright switches to compensate for any reduction in highs when using in-line effects. The Loop-a-Lator is a clone of this device.

Warning: this device does change your tone substantially making it slightly darker and more mellow, hence the 'bright' switches. You need to select the correct tube (internal to the device - I use a NOS JAN-Phillips 12AX7) and set up your amp for your desired sound

On the Loop-a-Lator there is an effects send and return. I take the send through a BSS AR416 Direct Inject (DI) box and out of the direct out into the input of the mighty Lexicon PCM70. I set the dry/wet mix of this between 15-20% and the output back into the effects return of the Loop-a-Lator: sounds lovely.

The balanced output of the DI box (with the earth lifted) then feeds the balanced input of a TC Electronic 2290 delay. The 2290 has a number of effect send and returns and in one of these I have another Ernie Ball volume which controls the amount (level) of echo return. This then feeds a Marshall Valvestate amp and then into a 1x12" TwoRock speaker fitted with an EVM12L. This gives me complete control over the amount of echo that come back though the separate cab.

Speakers and cabinets

Again I have owned piles of cabinets, loaded with a variety of speakers:

I think that the finest speakers to match the 'Dumble' style amps are the Electrovoice EVM12L. They are a slightly harder sound than Celestion's with smoother mids / highs and don't break up at volume.

I currently own three of these speakers; two 70's vintage and one re-cone (I lent it to someone who kindly blew it up).

They are loaded into TwoRock, open back, signature 2x12 and 1x12 cabinets; again Dumble clones.

The good news is that Electrovice have reissued them and they sound broadly the same as the originals...

Loads of great people with fantastic tones use Celestion's: I just don't like them in open backed cabinets. I may buy another 70's Orange 4x12 at some stage, they sound great.


OK, you have gone to all this trouble and at the last stage you can lose the whole effect by poor microphone selection and management when 'miking' up live and in the studio.

My favourite for miking guitar cabinets are Sennheiser 421's with a second choice of Shure SM57. Microphones must be carefully placed to obtain the sound that you like: listen to the output!

Movement of a few of millimetres can affect the sound. I usually get my ear as close to the cab as possible and select the sweet spot. This usually ends up with the microphone near the edge of the speaker parallel to the cone (so it looks at an angle). If you have it up at the centre of the speaker, it's normally a bit harsh.

An AKG 414 as an ambient microphone, in a well acoustically designed studio, can also enhance a great sound.

Of course in the studio, it's easy, just play, record and listen back. The disadvantage here is that you have to keep running in and out of the studio to record again if the the microphone(s) are moved, then listen back.

You can of course play in the control room, but this has its own set of problems due to the cable length into the studio area which sucks tone (see the previous article). There are devices which you can use so sort this out such as the Little Labs PIP instrument distribution system or my new toy the Radial Engineering JX44 & SGI44.

Top tip: If you are using multiple microphones on one cabinet, toggle the 'phase' switch on the desk to make sure the ambient and direct mikes are in phase.

Live however, you are the mercy of the engineer; all you generally hear is your own amps and the stage monitors... So, choose an engineer that plays guitar and, most importantly, don't be an arrogant arsehole: be nice to the crew. Your tone will benefit :-)

And finally...

The best tone you will even achieve is a great guitar with well tuned pick-ups and electronics, a great guitar cable, a great well serviced amp and complimentary speaker cabinet connected with a nice thick speaker lead. That's the place to start then just add on what you need!!!

The final part will feature a bit of history about what I have used and why I changed, my ‘tone ‘influences’, detail on why I use the specific kit I have now plus old photos of me and my gear.

Of course, if you have any questions why don't you contact me or post a comment below!


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