Vintage amplifier cabinets and amp restorations

Here is the "before" picture of an old 1961 Fender Concert Amp that I restored to original. The amplifier was in a fire in the back of a truck. Someone through out a cigarette and it caught fire!!
I love working with the old amps, they always tell a good story. I have seen so many cool old amps, if I only had a hand full of them for my music room!!!

Here is the "after" picture. Not as much character but it will get broken in with time.
I always save the old materials for the customers, it has the amps mojo in it so I suggest
keeping it in a box.

When restoring old vintage cabinets I like to only use cake or enzyme glue, like most vintage amp cabinets would have been upholstered with.
Not only is it "vintage correct" but it helps with tone by allowing minimal dampening on sound waves.
For an example imagine a bell. It sounds very loud in its uncoated metal state but if you were to dip it in wax and then wring it the sound would be dramatically decreased.
This is what happens to guitar amplifier cabinets that are covered with more modern adhesives. The material will dampen it already so why add to the problem by using the wrong type of glue, in my opinion. If you are a tone freak then this is very important and should be considered when commissioning your your next custom cabinet.
This glue is quite expensive as compared to most other glues used in the industry but sometimes you have to pay for the best things in life.
I like working with it because it is non toxic and good for the environment.
Here is a picture of a slab of the glue I use when applying material to a cabinet. It works better on tweed than on tolex, so if you are using it for the first time, be patient; there is a learning curve to use the glue properly, and it will burn if you get it too hot which kills the enzymes and renders the glue unusable.

Alright, now as promised I will tell you the main ingredients for making a custom amplifier cabinet that sounds great. For some of you this may be common sense but over the years of listening to different cabinets I have bestowed a certain knowledge that I know is the "real deal", so if you want to build a cabinet that will definitely sound great just follow these simple steps.Keep in mind that we are talking about guitar amplifier speaker cabinets here. Not to be confused with acoustic suspension, bass reflex, folded, public address, or other cabinet designs that are intended for different applications.

1. Select a resonate wood that is soft in nature, and make sure it is cured well. Ideally the best tones will come from a light piece of wood so be selective when picking out yours. I have left the store many times empty handed, so be patient. I always use only solid wood with minimal grade #2. My most common board would be a 3/4" 1" X 12", #2 pine. There are various mills they come from but the important thing is to get a piece with minimal knots and good continuity. By this I mean to look at the grain and look for a similar grain throughout the board.
This usually can mean that the tree was not damaged by man or nature, and has full integrity in its structure.
Ok now I am probably getting over your head. Just get a good looking board that has the least amount of knots and is dried well, very light in weight. Poplar really sounds nice too, but will cost a little more that pine. It has a nice tight grain that looks nice if you are not going to cover your cabinet.

2. Get your cabinet design from a proven cabinet and by that I mean a cabinet that you know has been played through and sounds good, remember that if your amplifier does not inspire you then what is the point in plugin in. Many of the vintage cabinets sound good but some much better than others. The biggest fault in designs I have worked with is not enough volume. You really loose the juicy fat low end of a cabinet when it is too small in volume, and there is actually a sweet spot that can be tuned in if your cabinet is built correctly. Back panel placement and spacing really helps tune your cabinet. Basically letting the right amount of waves escape with out over doing it and letting to many waves out to get full sonic resonation of all elements in the cabinet is the proper tuning of a cabinet. Your wood will sing if you give it the chance, just ask Eric Johnson!
So get your cabinet designed from someone who has experience is the industry of guitar amps, not just the local cabinet shop.

3. Use good joinery techniques to achieve maximum strength and sonic integrity. I always use finger joints or dove tails when making a cabinet. Finger-joints actually are the best in my opinion, as they have the most surface contact, which means less loss of sonic integrity
and or continuity. As an example take a 1/4" wooden dowel and make contact with one end of it on an acoustic instrument near the sound chamber. Strum it and get a feel for the sonic waves it is picking up. Then get a bit larger dowel like a 3/4" and do the same. You will notice more transfer in the larger dowel. It is really just simple physics.

4. Next you need to make a good baffle (speaker) board to install your speakers on. For floating baffles you want a strong yet flexible ply wood.
A floating baffle is one that is attached only on two opposite side. This gives it more flexibility, which guitar amplifier speakers like, at least in most cases. A lot of the old vintage Fender Amplifiers that I like have the floating baffle, and I build most of my custom cabinets with the floating baffle if applicable. For lighter speakers I normally use 3/8" ply for 10" speakers, 1/2" ply on 12" speakers, and 3/4" ply on 15" speakers. I try to use fur ply because it is more flexible that birch ply, but if I am installing heavy speakers(like JBL's or something) I will stick with the birch ply because of it's strength. Ultimately it is up to the customer but I like to suggest my favorites.
I do not like to use t nuts as they tend to get stripped out over time(usually because someone is not taking their time) and you do not get as good of a contact as compared to studs drilled through the speaker board and attach the speaker with speaker nuts. This application is also easier to apply lock tight to if you need to.

5. One last suggestion is to not drill any unnecessary holes into your cabinet, and keep hardwares to a minimum. By this I mean not to install casters, corners, large handles, etc. unless it is completely necessary. For example, if it were up to me I would build a Marshall Replica without the casters. I would keep the large handles because they are necessary to move the cabinet around but the application of casters can be achieved without drilling and installing them on the speaker cab. You can use a caster tray for this. Also if your amp is not on the stage and is sitting on casters you will loose tone!! Lift it off the caster tray before you jam.

If you follow these steps you will end up with a great sounding cabinet for your hand made tube amplifier Always be careful when working with power tools and wear eye protection at all times. Safety is always first. It will be hard to play if you are missing a tinnacle.

I am going to tell you why American and British Guitar Amps sound different. If you understand what I just explained then this should be easy to understand.
For example purposes I will use Marshall amps and Fender amps. Obviously Marshall amps are British amplifiers and Fender amplifiers are American amps. Anyone who knows much about guitar amps can tell you that the Marshall's are more heavy rocking amps while the Fender's are suited more for blues and country. Most Vintage Marshall amps have a master volume, as well they have more powerful transformers and tubes than their American counterparts. Also all Marshall cabinets are made from baltic birch ply and use birch baffle boards which are fixed, not floating, as described earlier. This makes the Marshall amps very punchy and bright sounding and the master volume allows you to get much more distortion at all volumes, unlike a Fender with no master, the typical vintage setup for a Vintage Fender Amplifier. Also the common landmark on stage for Marshall would be their half and full stacks, which were typically either 50 or 100 watts, as compared to Fender's tweed bassman at 40 watts, and the hi power Twinn at 80 watts, also with a lower bias, which made Fender amps more desired for warmer tones, like blues and country and jazz.
Vintage Fender Amplifiers were made with solid pine cabinets and fur baffle boards which sounds much warmer than Marshall's. They were generally more open backed than Marshall cabinets too, which made them less punchy and easier on the ear for listeners at a live show.

Although this site deals chiefly with amplifier cabinets, it is important to understand that tonal qualities come from both cabinet and amplifier design. With this being said it is an interesting fact that both the Marshall JTM 45 and the Fender 1959 Tweed Bassman amplifiers both stemed from a modified version of the old Western Electric circuit, so no one has reinvented the "wheel" we just make modifications on what was already there before most of us were born!!