cabinet build - leaving space on each side of the chassis

[pjd3]

Hello,

While I assume I could figure this out myself, it would be good to know if there are any standards or optimal space you leave on each side of a chassis. This is when dimensioning out the size of a combo or head cabinet.

Thank you. Im almost ready to make my first combo cabinet with a Princeton reverb sized chassis and a single 12" speaker.

Best,

Phil D

[xtian]

Width of cutout for chassis should be 0.25" wider than chassis for a snug fit, or +0.3125" for some breathing room.

[Phil_S]

You can make the box any size you want, but a wider box will require blocking to make a proper chassis cut out as xtian says. There are aesthetic considerations. For a combo, I'd say you want a ratio of about 3h:4w . For a head I think about 1:2.5 (something like 8"h x 20"w) is OK.

[pjd3]

Thank you, this all sounds like good recommendations, and I will be guided as such.

This amp (stereo amp) will be built using a Twin Reverb chassis (24 3/8" x 8 1/4" x 1.75") and will have probably 2 x 12" speakers just like a twin, so about the same size cab.

I was thinking on going 10" speakers for keeping thinks as compact and light as possible but, more impressed with 12" speaker offerings. Someday I may do a 10" version, we'll see.

So yeah, your recommendations are pretty much inline with my thinking. It's always still good to hear a backup opinion.

Thank you very much,
Best,
Phil D

[Phil_S]

You might look around for the golden ratio of a speaker enclosure. This is more typically a hi-fi topic for closed back. Nevertheless, it's useful reading. Assuming an open back combo, you get considerable latitude in the dimensions, but the golden ratio will give you a good starting point for something that's reasonable.

Remember, you don't need to mount 2 speakers side by side. They can be set upper left and lower right, which will allow for a narrower baffle. I mention this because your minimum width is set by the chassis. 10's will fit. For 12's, you might get by with offset mounting. There needs to be some meat between the two speakers. I'm not sure of the minimum -- I'm thinking more than 1".

Nothing wrong with 10's. I'd go for 12's. The difference in surface area is quite a bit. The comparison is based on the square of the diameter. 10's give you 100, 12's give 144. 12's are 44% "bigger."

[pjd3]

Thank you for that input Phil.

For this first stereo amp its going to be an open back so I guess I can relax on this specifics of dimensions. Fortunately, since it is a Twin Reverb Chassis I'll be using there will be no problem with two 12" speakers side by side. It was actually tempting to use 10" not just for economy of size and weight, but to create a little larger gap between them for creating a little more audible "onstage field spread". After all, the amp will also be acting as my onstage monitor. Each speaker is intended to be separately miced and and panned fairly hard L & R out the PA so that the audience hopefully gets a near full experience of the stereo reverb, delays and any other processing units that are stereo on my pedal board.

I now have a fairly close idea of external layout, now its just a matter of One vs Two power transformers. I do see worthy benefits of either but I believe they can both be made to work well with some attention to electronic details, grounding and such.

Thanks for your good ideas,
Best,
Phil D

[Phil_S]

For stereo, you may want to consider an internal divider between the speakers, internally looking like two boxes. Good luck with your project.