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Old 18th September 2008, 09:47 PM   #1
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Default Enclosure for tube amp/speaker/reverb unit

Does anyone know of any web pages about making your own combo enclosure.I have searched and come up with almost nothing.

I know there are new enclosures for sale but they are too expensive and anyway I think it would be fun to make my own combo cabinet myself.I have a Hammond organ tube amp which I am restoring/modding and need a combo style cabinet to put it in along with the spring reverb unit and a Jensen P12S speaker.

There is nothing about this on the other forums so I thought I would ask you tube people.
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Old 18th September 2008, 09:58 PM   #2
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You should find your sound by trying different thicknesses of plywood to find which resonances sound the best for you. It is not for a violin made by Stradivari. It is for a guitar that has no resonating surfaces so sounds dull and unarticulated, so the real live acoustical sound has to be made by the speaker cabinet. I doubt that somebody would reveal results of hard expensive way of searching for the sound.

Good luck!
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Old 18th September 2008, 10:30 PM   #3
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OK, so for a start the material must be plywood?

I was thinking that really all I have to make is a box with an open back which is simply big enough to mount an amp chassis in and a 12" speaker,nothing too elaborate,it's not like I am making a HiFi speaker enclosure.
I have a book on HiFi loudspeaker design and it seems a complicated subject.Do I have to apply the same rules for a relativley "crude" guitar amp(compared to HiFi amps/speakers) or will a plain old wooden box do?
Maybe I should ask the loudspeaker forum too.

Edit: Would a badly designed cabinet ruin the sound by microphony and vibrations affecting the tubes and reverb unit or am I being too fussy?
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Old 18th September 2008, 10:45 PM   #4
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Specifically if you can get it, baltic birch ply, and to start perhaps 3/8" thick for the sides, partially open back and 1/2" or 3/4" baltic birch baffle board. Mount the driver from the back.

Cabinet can be 10" - 14" deep typically.

Build it sturdy so that it does not buzz or rattle. Reinforce the inside corners with blocks, and glue and screw everything! Do not stiffen the panels!

Install the reverb inside a bag designed for the purpose - this will prevent/reduce acoustical feedback.

Try to place the speaker somewhat asymmetrically in the baffle board to reduce modes in the baffle board.

Your sound will be determined most by the driver choice followed by the cabinet.

Look here for some ideas:
I Have Finished My Standell 25L15 Clone
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Old 18th September 2008, 11:18 PM   #5
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Is the baffle board the board that the speaker mounts on?

I see from the pic how he offset the speaker to one side.

So as far as construction goes, what you are saying is just personal taste,good workmanship and common sense and not all these calculations and stuff like with HiFi speaker boxes?
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Old 19th September 2008, 03:06 PM   #6
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by Aidan135711
Is the baffle board the board that the speaker mounts on?

I see from the pic how he offset the speaker to one side.

So as far as construction goes, what you are saying is just personal taste,good workmanship and common sense and not all these calculations and stuff like with HiFi speaker boxes?

Pretty much right on all counts... Build one, worst case you learn what doesn't work and you then try something a little bit different, but in most cases as long as you built it sturdy to avoid buzz and rattle you should end up with a reasonably good to great result.

Yes the driver is mounted on the baffle board, and this should be a bit thicker and stiffer than the rest of the cabinet.

Use cleats in the corners and it is not overkill to do it everywhere. 1" x 1" stock is large enough to screw and glue. Miter joints are nice, but not necessary, you can use butt joints just make sure the ends are very square and fill the joint with plenty of glue so that it does not buzz.

Void free marine grade baltic birch plywood is rather expensive, I have had some good luck with cabinet grade BB ply, however this is not guaranteed to be void free. Voids can buzz..
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Old 19th September 2008, 03:29 PM   #7
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I am a retired Elecrical Engineer and I build musical instrument amplifiers as a small money making hobby.

For a single 12" speaker a good starting point would be the Fender Deluxe Reverb cabinet which is an open back combo amplifier.

The dimensions are 24.5 inches wide, 17 inches high and 9.5 inches deep. Fender uses Southern Yellow Pine for there cabinets, but I have used Poplar, Aspen or plywood as it is readily available at my lumber yards. The cabinet should be made with 3/4 inch thick sides and top. The speaker mounting board should be 1/2 inch plywood preferably 7 layer ply, 5 will work. The back pieces can also be 1/2 inch thick.

New Sensor Electronics in New York or Antique Electronic Supply in Arizona has lots of component parts for building amps and both carry padded bags designed for holding the reverb spring.

Hopefully this will give you a good starting point.
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Old 19th September 2008, 03:57 PM   #8
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I build guitaramps, http://www.revintage.se .

Build your cabinet in 16mm fingerjoint pine for the sides, 10mm pineply for the baffle and 7mm for the back. This helps a guitaramp to get a nice tone. I love the size of the Princeton Reverb adjusted to take a 12" or 15" speakar.
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Old 19th September 2008, 05:00 PM   #9
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Quote:
Originally posted by kevinkr
[B]Specifically if you can get it, baltic birch ply, and to start perhaps 3/8" thick for the sides, partially open back and 1/2" or 3/4" baltic birch baffle board. Mount the driver from the back.

<snip>
Whoops, I meant to say 3/4" not 3/8" - plus lots of additional good advice from other posters more experienced than I am.
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Old 19th September 2008, 05:44 PM   #10
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I agree with Lars, pine can also be used and it does give a real nice tone.

One important point. Mount the reverb spring on the bottom and try to mount the amplifier unit on the top of the cabinet. Keep the power transformer on the opposite side of the cabinet from the output transducer in the reverb spring. This keeps the hum to a minimum in the reverb circuit.

Also, try to mount the speaker off center towards the opposite side from where the amplifer transformers are. THis helps to balance the amp from a weight distribution point of view.


P.S.

To all, I am finishing up the construction of a two channel combo amp with a single 12" alnico based speaker using a pair of 6V6GTs with tremolo and reverb. Channel one will be be set for Aux or Line level input using a Baxandall tone control. This will have a stero mixing input so I can plug in a mp3 player and jam along. Channel 2 will be a Deluxe reverb circuit with an added bright switch. The cabinet will be in natural wood stained in dark oak rather than covered in the usual Tolex vinyl.

I will post pictures in a few weeks of the completed project.
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