Equipment Design

4 X 15 Bass Guitar Cabinets


Cabinets Fully Loaded With Either Fane New Range Of Bass Guitar Speakers, Eminence New Range Of Speakers, Or Celestion New Range Of Bass Guitar Speakers, Of Either Neodymium Speakers, Or Traditional Ceramic Magnet Speakers, From The Green Range, Or The Orange Range, That Can Be Seen From Visiting The Celestion Website, Eminence Website, And Fane Website. All These Speakers In Either 16 Ohms, 8 Ohms Or 4 Ohms, Making A Variety Of Different Combinations, For Either Stereo Or Mono Cabinets, With Different Ohmages From 2 Ohms, To 4 Ohms, To 8 Ohms, To 16 Ohms, Or In Stereo Cabinets That Are Either 8 Ohms A Side Or 4 Ohms A Side, (2 Ohms A Side, Is Not Recommended On Any Amplifiers, Unless Overbuilt Amplifiers Like R.s.e., Or Cambridge Audio, 707’s, Or 808’s, Or Any Other Amplifier With Gigantic Power Supplies)


This is my own prototype cabinet. The cabinet is 34¼” wide, 34¼” tall, 25″ deep. Favoured current speakers are regular vintage JBL E140 or K140. Cabinet wiring 2 sets of 4 ohms. Speakers individually compartmented. Centralised porting. Internal acoustic padding. Current speakers loaded into this particular cabinet that you see here, are Brian Gillaes customised JBL E140 speakers. Titanium formers, edge wound voice coils, Square wound copper windings. Carbon fibre/kevlar/paper cone mix, capable of 1500 watts each. In my opinion, manufacturers haven’t made a speaker as wonderful as the JBL E140, or K140 since.


This prototype cabinet is equivalent to two 8 x 10 cabinets in power. This 4 x 15 is utterly devastating because of the following factors. Each 15″ speaker is in its own box, with its own porting.

Which makes 4 single 15″ speaker cabinets in one box.

The depth of the cabinet produces a lot more clear bottom end, because of the depth behind the speaker, and the special acoustic padding, installed in a specific fashion, to break up standing waves inside the cabinet.

There are two ports per compartment, with the central porting, organised and located in the centre of the cabinet, producing the most fantastic amount of articulate bottom end you have ever heard.

In development stages, I have tried this cabinet with four 15″ aluminium cone speakers, which gave a clarity all of its own. But it has been found, that 10″ aluminium cone Hartke speakers in either 2 x 10 or 4 x 10 or 8 x 10 configuration cabinets, work well with 15″ paper cone or paper/kevlar/carbon fibre mix speakers, in the deeper sounding full range cabinets, producing a magical combination of the two different types of speaker cabinets, working in conjunction together. In layman’s terms, if you stick 15’s down the bottom, made of paper-mix cones, in their own boxes, and you stick 10’s up the top, made of aluminium, in their own boxes, you will get terrific sounds. Many American bass players will tell you this on the circuit, after discovering the combination of the two.

I had wanted to build a 4 x 15 bass cabinet for years.

I originally had 4 Marshall 4 x 15 bass cabinets, 2 slants, and 2 squares. And 4 Marshall major 200 watt heads. I wasn’t very happy with the cabinets, as they were not deep enough, using the original spider leg Celestion 15″ speakers with 1½” voice coils, which broke up under the slightest pressure, giving Jack Bruce sounds all the time, but deeper.

I realised after putting 4 JBL K140 speakers in these Marshall 4 x 15 cabinets that it wasn’t going to work, a bit like the Mesa Boogie road ready 4 x 10 cabinets, with David Eden 10″ speakers, that weren’t very deep, not giving much bass, with the 400+ or the earlier 400 Mesa Boogie bass head. Mesa Boogie later brought out a deeper 4 x 10 called the deep bass, with 10″ Electro Voice speakers, which was much better. I had two of these stacks, and realised that the 2 x 15 Mesa Boogie ported bass guitar cabinet either in diesel or road ready was much better, with the Electro Voice 15″ speakers, instead of the Mesa Boogie 4 x 10 cabinets with David Eden 10″ speakers. In layman’s terms, the big Mesa Boogie 400 heads work better with the Mesa Boogie 2 x 15’s. Tim Bogart proved this.

After building this cabinet I dreamed up, and spending utterly yonks, and lots of time working it all out, this cabinet is very clear, and very articulate, and above all will utterly demolish any other cabinet that I’ve used.

In short, it’s absolutely huge sounding. Huge and clear, lively, and is unlike any other cabinet you’ve ever heard. If you’re a rock player, it makes a guitarist with a Les Paul, a Plexi or tin front super lead Marshall, with 4 x 12 G12H Celestions, crank right up to the top like Mel Galley used to do in Trapeze, sound like a combo compared to this cabinet.

Used with an Ampeg SVT all valve head, and the JBL E140’s, that don’t require a lot of watts to get moving, it blows the living pants off guitarists, in this rock situation. Obviously, it’s not as far travelling as 4 Martin bins, and 2 200 watt Hiwatts, like Pete Wright used to use in Trapeze, or Glen Hughes, using 8 Martin bins, with Gauss 15″ 4580’s or 15″ 5840’s, with either 2 or 4 Hiwatt 200’s, or 2 or 4 Hiwatt 400’s in purple. This particular bass rig of Martin bins and Hiwatts was a glorious rock sound with a Fender bass.

What I wanted to do, was get the acoustic coupling like in other cabinets, but with the acoustic coupling of 15″ speakers with centralised porting. This cabinet is very portable and not heavy, for one big geezer to lump on and off a van in a gigging scenario in a rock or blues rock band. I realised if guitarists love the spread of a 100 watt head, with a 4 x 12 cabinet, then a 400 watt tube bass head with a sequentially larger cabinet for bass guitar, would be the commensurate equivalent to the guitar half stack, so the bass player could have a half stack that would run with it, and be able to have enough clean headroom.

The old JBL speakers are high efficiency, and sensitive, and high decibel output, on the old cast chassis, with either alnico magnets or ceramic magnets, didn’t need a lot of watts to get them going. I learned this from a lecture from Norman Watt-Roy, legendary bass player, who has an old CP flight cased 2 x 15, with JBL K140’s alnico magnets, 150 watts each, totalling 300 watts for the cabinet, and an old Trace Elliott 300 watt valve bass head, his cabinet pushes out a phenomenal amount of grunt, which I discovered when he was with Wilco Johnson.

Colin Pattenden of the Manfred Mann Earth Band fame turned me on to the Gillaes 15″ upgrade, with the high technology that Brian Gillaes developed in these JBL E140 speakers. I discovered that they are absolutely sensational, but no longer available today.

Obviously, the old speakers that don’t require a lot of watts to get moving, are highly musical, and very sensitive, like Billy Cox’s Band of Gipsies bass rig, that he used to use with Jimi Hendrix, using six Guild 2×15 JBL K140 cabinets, with eight Fender 50 watt tube bass amps, also using old Fender P.S.400 valve heads (that are extremely unreliable head, due to the valves being pushed to the absoute limit, and melting the glass, and needing constant maintenance to keep working properly, being subjected to such high plate voltages. I had a load of these Fender PS400’s, and Fender PS300’s, with phase splitter transformers, that give a unique sound all of their own in these amps, which has not been replicated since, but they are too much trouble to keep going on the road.). These old JBL speakers in the old 2 x 15’s, and the old Fender Earthquake bins, that go with the old PS400, push a lot of air on not a lot of watts, and are extremely musical speakers.

Obviously, you could put 1500 watt speakers in this box, making it a 6000 watt box, with a 6000 watt power amp, a 32 band graphic, or a 16 band graphic, with a pre-amp, and it would be utterly devastating, but it wouldn’t be very musical with such heavy cones like the eminence kappa 2’s that push a lot of sub-bass, but aren’t musical. So you can overdo it, by putting in power pistons, and watts are cheap these days, not like when I grew up when big wattages were hard to get, like the Phase Linear 700, which was the biggest power amp around at the time, before RSD and Martin rigs for out front, when every band had to have their own truck, own back line, and own PA, and own lights, and own mini crew, and maxi headaches, and endless bollocks of keeping this all rolling, like a nice tight ship, when everyone was off their face on something, which pissed me off no end, coming from a background in East Grinstead, Sussex, England, that utterly frowned upon drugs, and made it clear all the reasons why this was.


I had tried a 4 x 18 with 18″ JBL’s, but 18″ speakers are too slow to respond to what a bass player wants. I know that Jacko with his acoustic 360 rig, with the power amp and the 1 x 18 bin, had got a good sound, by turning the treble all the way up and limiting the bass, but it must be said that the Cerwin-Vega 18″ 4 ohm speaker in this cabinet has a deep cone configuration, and a smaller voice coil, handling frequencies differently, unlike the shallow configuration of the JBL K140, E140, 2225, etc., which is much loved by bass players because of their clear, articulate sound, and the aluminium dust cover that covers the voice coil, giving a bit more treble.

The 4 x 18 is utterly unwieldy, and the speakers are too slow. 18’s work best in pairs, or singly, I have found. So a 4 x 18 is too low end mess, as is a 30″ speaker in one box, that I used to have, which requires so many watts to move the gigantic voice coil, and is so slow to react. So the bass rig of a 4 x 10 and a 1 x 18 is a real shame, because the 18 takes so long to stop moving, and get going again, compared to a 1 x 15 on the bottom underneath a 4 x 10. In layman’s terms, in a rehearsal situation, when you hear a 4 x 10 and a 1 x 15, sounds tight, but when you hear a 4 x 10 and a 1 x 18, the 18 is dragging its feet, compared to the 4 x 10.

The 4 x 12’s of today sound absolutely glorious, like the Marshall 4 x 12 for bass, which is a cabinet which is divided into two halves. When you put two speakers in one compartment, they think differently than if they are in their own compartment, and need less cubic capacity to do their thing, so you can make a smaller box, which is more tight and compact around the front baffle board, and not so deep. But if you put the drivers each in their own compartment, something entirely different happens with the articulation and the acoustic coupling.

Phil Jones 16H cabinet knocks the spots off any 8 x 10 with its tuned folded horn arrangement, I have never heard anything like this cabinet of his. It is a very great shame he discontinued making his T500 valve head, with gigantic 813 power tubes, producing 650 watts of bass power, which is the most outrageous tube bass head I have ever heard. This 4 x 15 can keep up with the Phil Jones 16H, and if the truth be known, can outrun it.


You see here an Ampeg SVT tube head, a Fernandes 5 string passive bass, with Kent Armstrong special pickups, from Aaron Armstrong, this passive bass with this tube head and this cabinet, produces the most fantastic sounds, either from jazz type noodlings, or Larry Graham funk thumb-driven rock funk grind type grooves, like the Chilli Peppers, or playing with a plectrum like Alan Roberts, from Stray Dog, on his Gibson Thunderbird bass, or playing finger style rock in any style, or shuffle grooves or swing grooves, it is the most outrageous cabinet I have ever heard.

I normally use an Ampeg 4 x 10, with 4 Hartke 10″ speakers, with a Classic 1 x 15 cabinet, with a JBL E140 normally aspirated speaker, also with an electro voice eliminator bass bin, with a Gauss 200 watt bass speaker in it.

That setup is the most fantastic rig for a rock covers band, playing funk and rock and soul all night, the bin, the bottom cab, and the top cab, and a SVT head, will keep those feet movin’ and a groovin’ all night long, but let it be known that my new 4 x 15 has now done a Mike Tyson and won the day for now.

I’ve got an old Ampeg V4-B 2 x 15, with special speakers in, that is ridiculously good sounding cabinet, that has a character all of its own, so as you can tell, I’m a tube amp guy, because tube amps don’t hold on to the speaker excursions like a transistor amplifier does.

The Ampeg SVT PRO 8 has digital power, and is 2,500 watts, which sounds even different again from a SVT PRO 3, and holds on to the speaker excursions even more tightly, which is, I suppose, good for some things but not for others. Michael Anthony from Van Halen, turned me on to Ampeg SVT’s in the 70’s, as did Mars Cowling from Pat Travers’ band, with Niko McBrain on drums. Mars told me about his beloved Hiwatt 400, the same as my 2 Hiwatt 400’s that he used to have. This is a lovely amplifier, but I must say that the SVT, or the Mesa Boogie 400, which has 6 6550’s in it, sounds much better than the Mesa Boogie 400+ that has 12 6l6’s in it, that only pushes 250 watts on a scope, whereas the 400 pushes 300 watts on a scope. The old SVT mark 1’s push 350 watts, not like the new SVT PRO’s that only push 300 watts. The reason the Mesa Boogie 400’s, and the 400+ sound so huge is the front end pre-amp in relation to the power stage, a bit like the SVT, which has a fantastic front end that gives it this astounding sound.

The Ampeg SVT PRO 8, sounds outrageous with my 4 x 15 that I designed, but it’s just too much, and the speaker excursions aren’t the same, as a tube amp.

I got this idea for a 4 x 15, by trying 4 community 4 x 15 cabinets, and 4 Marshall VBA 400’s at a festival. Whilst doing so, I realised that if you divided the cabinet up, made it deeper, and organised the porting in the middle, you were onto a winner, provided you had got the cubic capacity, and all the other variables, worked out to the n’th degree. In short, this cabinet is an absolute mother, it’s not very big, it’s not very heavy, but boy, does it do the business!

You can always contact me and ask me questions about stuff,I have been interested in bass gear, and guitar gear my whole life, and was first struck by this at the first gig I ever attended, which was Jimi Hendrix experience at Hastings Pier Pavilion, with Jimi on Marshalls, and Noel on Sunn Colluseum 200 watt bass heads, and the old L4 Sunn 2 x 15 JBL ported bass cabs. And then hearing shortly after Jeff Beck on Marshalls, and how he got such a fantastic sound out of a tin front JMP50, which is one of the best heads I have ever heard.

But then again I have heard Tim Bogart on Mesa Boogies, which floored me, and then again Jacko on his acoustic 360 rig, and Colin Pattenden on his complex powerful rigs, so I was utterly hooked at figuring it all out, the relationship between instrument, pre-amp, power amp, speaker, and speaker cabinet, and the inter-relationships of all this, whether exponential horn flare cabinet, or ported cabinets, or sealed boxes.

Obviously the speaker box is the last link in the chain, which is what you hear after everything else has been through it, and the final sound shaping of the cabinet itself with its speakers in it. A bit like a double bass really! Which is why Tommy Shannon likes plain wood cabinets, because he reckons the surface of the box has got something to do with it as well.

The recommended amplifiers that I suggest using with this 4 x 15 cabinet are Ampeg PRO 4, or Ampeg PRO 8. You could use an old PRO 5, or two PRO 3’s. I also recommend the SVT PRO 2 on one cabinet. You can use two PRO 2’s on one cabinet. You could use an Ampeg 1600 slave with SVT pre-amp. I have tried lots of other amps, and some of them run out of steam, that don’t really cut the mustard. In order not to offend anybody, or any manufacturer, I can’t name anything specifically, but experienced bass players will know what’s what.

You could go down the route of pre-amp, and slave power amp. A good choice would be a Alembic F-B1 or Alembic F-B2 coupled with a decent stereo slave amp. The old C-audio is nice, but then again, so are the big Ampeg stereo slave amps. It is important that power supply and transformers are huge, in order to develop proper bottom end. I’m still experimenting with power amps and pre-amps, and have found some pretty startling combinations to use with this cabinet.

4 X 15 Cabinet, 4 X 10 Cabinet, 2 X 18, 2 X 15, 4 X 12

After much research and development, it was found that depth of cabinet produced depth of bass.

An intrinsic design feature of cabinetry, for the reproduction of bass guitar, especially 5 string bass guitars, totally unlike traditional 4 string basses, it was found that depth of cabinet had a lot to do with the reproduction of the bass frequencies and low end response.

I experimented with 1 x 18’s, of the 4 x 12 size bass guitar cabinets of the traditional HiWatt and orange and Marshall configuration, and it was found with acoustic dampening material, covering most of the inside of the box, that a shallow depth cabinet of the 4 x 12 size, in fact housing a 1 x 18 speaker, took out all of the woof and elongated ring-on of deeper 1 x 18 cabinets, like Trace Elliott 1 x 18’s.

This shallow cabinet of a 4 x 12 size, but in fact housing a 1 x 18 full-range bass driver, was very articulate and very expressive, but had very little low end to speak of.

Experimentation found that by having a smaller front to a cabinet housing a 1 x 18, and greater depth behind the cabinet, produced clear articulate bass, just like the 1 x 18 cabinet that was traditional HiWatt shape, just like a 4 x 12, with the added design feature of greater depth behind the cabinet.

BINGO! The result of the clarity of 4 x 12 size, and the bottom end of a deep cabinet.

I had been through a vast amount of speaker cabinets and amps in my life, always interested in what produced the sounds that attracted you to that particular cabinet you were working with at the time, but also what it lacked and why this was the case.

I tried endless configurations. Every single cabinet produced for bass. Scoop front loaded bass bins, like Michael Antony’s first Van Halen 70’s rig, 4560’s, 4580’s, Fender cabs, Marshall cabs, HiWatt cabs, Orange cabs, early Laney 4 x 15 cabs, Martin bins, acoustic 360 bins, acoustic 301 bins, Turbosound, TSM 115’s, Turbosound 2 x 15’s, function 1 cabs, you name it, I was going to stick different speakers in them, and try them with different amps till the cows came home.

Research found that small surface area to the front of the box, with depth of cabinetry behind the speaker, with porting, produced the results thus far looked for, with acoustic coupling.

The acoustic coupling of the 4 x 15 cabinet really handles the 5 string bass guitar, especially active 5 string bass guitars, as well as passive 5 string bass guitars.

The speakers that I have found that were available easily, without endless nonsense from suppliers and manufacturers, were Celestion and Eminence in England.

This may be a different situation in the USA, or Europe.

The 4 x 10 small front deep box is a fantastic 4 x 10 for a small gig bass player.

The 4 x 15 small front deep box is a fantastic all round cabinet for anything.

The 4 x 12 small front deep box is a fantastic box also, but harder to find bass drivers for.

The 2 x 21″ small front deep box is utterly outrageous low end.

The 2 x 18 small front deep box is a fantastic low-end cabinet, a bit like youths Peavey rig in Killing Joke, the old Peavey 800 heads with 2 x 18 plus 2 x 10 in one box. They did make a 2 x 18 only that was absolutely fantastic cabinet, much favoured and sought after by some heavy metal bass players from the USA, because of the monstrous low end.

All of these speaker boxes have acoustic coupling of more than one speaker in pairs, or in bigger configurations. It was found that each speaker works extremely well in its own container inside the cabinet, so in laymans terms, each cabinet has its internals divided up as per speaker.

It was found that two drivers in one air space, or box, had a strange phenomenon, of that the left hand driver, sharing the air space with the right hand driver, thought that the entire air space was just for itself, and vice versa for the right hand driver, also thinking that it had the entire air space all to itself. Then, tuning the cabinet, by moving the back baffle up and down the cabinet’s depth, in order to find its optimum function.

8 x 10 Guitar Cabinet

Having grown up in the late 60’s and early 70’s and early 80’s time frame, the Marshall 8 x 10 guitar cabinet was a sensational piece of kit.

The Marshall 8 x 10 slanted guitar cabinet, coupled with a JTM45 or, more preferably, a JMP50, was absolutely glorious noise, and because of acoustic coupling, had fat bottom end.

After hunting the second hand market all over England, Ireland, Scotland and Wales, including Cornwall and Norfolk, in every single place that you could possibly ever think to hunt, like Cash Converters, Diamond Ads (the equivalent in Los Angeles would be called “The Recycler”), car boot sales, garage sales, door-to-door hunts, word of mouth enquiries from provincial music shops, run by anaesthetised deadbeats, more often than not regular pot smokers, and regular drinkers, who wouldn’t know what a detox programme and orientation therapy was (Purif and Objectives to you, son), if it hit them round the face with a wet kipper…………………………… it became painfully obvious, that it wasn’t possible to crowbar 8 x 10’s out of the woodwork, because the relatives had taken them up the dump, because the Marshall badge was missing from the front.

I realised that 8 x 10’s for guitar just weren’t around, period.

And, the only thing that I could possibly do was find a decent cabinet shop to remake them, with a few minor improvements.

Upon initial prototypes being made up, I realised that experimentation might reveal up a few things, and I tried the Ampeg bass 8 x 10 trick of four separate compartments of 2 x 10’s. This made for a very clear, very acoustically coupled, cabinet that didn’t inter-react, like the old Marshall 8 x 10’s for guitar. The next stage was a deeper box, with a totally inter-reactive internal air space, with the same slant on the front, but a deeper box all round. This produced even fatter bottom end than the originals, and using modern speakers that were totally unlike the old Celestion G10’s that were 15 watts each with a 1″ inch voice coil, and even some of them were ¾” voice coils, which broke up under the slightest pressure, and were only 10 watts each. Today’s replacement is the Celestion Vintage 10″ speaker with 1½” voice coil, which is also available with 1¾” voice coil, and extremely sensitive to low watts. This total wattage of 480 watts, would seem like too vast a headroom for a 50 watt head, but it is not, it works absolutely fine. I also tried Eminence 10’s that were 50 watts each, and Celestion’s that were 15 watts each, which are still available today, called the Lead & Bass 15 G10/15.

A shallow box, like the Marshall 4 x 10 cabinet, much loved by guitarists who play blues rock, who use a 50 watt Cornell head, or a Cornford head, or a Soldano 50 watt head, or a Marshal reissue 50 watt head of some description, or even a Marshall 40 watt head, is a most wonderful cabinet, firstly because it’s easy to get in and out of a small car, and you can really crank it up on a small gig, for solo’s, controlling everything from the guitar, like the old one channel amps used to behave, and backing off the volume, for clean chording and rhythm. This 4 x 10 cabinet really cuts the mustard.

These Marshall 4 x 10’s of either slant or square, weren’t quite deep enough, I found. And I found a Marshall JCM 800 4 x 10 bass guitar cabinet that was deeper than the regular Marshall 4 x 10, and suddenly loaded with these Celestion Vintage 10’s produced a fantastic amount of clear, tight bottom end, just like the bass player’s, but loads of blues wailing crunch with fatter bottom end. Yee ha, I hear you scream.

The cabinet shop created my prototype Marshall-style 8 x 10’s that are deeper, with extra reinforced struts top and bottom instead of just one central strut, like a double bass. Two struts work much better in between each speaker grouping, three was found to be too many, and one is still a bit flappy and flabby. So it is possible to tune cabinets with strutting, just like a double bass, where you can change the sound post diameter to a greater diameter, with a tighter grain, and move the sound post 1¾” from centre of bridge leg, to centre of sound post, as a good starting point, and then move sound post either in for more top, and out towards the inner bout on the left hand front of your double bass, to increase bass. Obviously, you have to tailor the length and the angle to fit the carved front and back, or flat back and carved front, but this is a whole other area of investigation into what makes good sound posting on double basses, which I have been researching for years.

Cabinets with a front to back strut are sensitive to strut dimensions and placement. Just like on a double bass. Also, the box it is deeper, does make for deeper bass, instead of shrieking shallow boxes that aren’t particularly focused, and very belligerent, and not particularly defined in their behaviour. A bit like chav’s, which translated into English is council housing actually violent in police speak. To expand on this a bit further, IC1, IC2, IC3, IC4 are police speak for different ethnic groupings in descending order, I’ll leave you to work out which way this goes.

Lots of love.