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Speaker cabinet size questions.

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8/8/2000 1:26 AM

Speaker cabinet size questions.

I've just been to Weber's site and my head is reeling. I'd love to understand all the math envolved but I just don't have time to learn it. I wana build a Marshall style straight 4x12. How do I go about deciding the deminsions and how important Are they?

Weber lists a "golden" ratio for the cabinet dimensions but they don't seem to be the same as the Marshall cabinets I have seen.

What are your thoughts and experiences? What design will give me good performance without and resonaces or other badness.

I can handle the building but I need to know what to build before I start cutting wood.

Thanks to all, Firefly

8/8/2000 1:35 AM
rmike	I think the 'golden ratio' is used for the least amount of tonal coloration from the cabinet... However, tonal coloration from the cabinet can be a good thing. Many cabinets sound great by deviation from this ratio. I think you should identify what sound you want and use pretty close measurements of that cabinet. Mike

8/8/2000 3:01 AM

one thing to remember about those ratios is that they're taken from stereo cabinet formulas, where the ultimate goal is to get the flattest response possible. Since guitar frequencies generally cut off around 100 Hertz, and you don't hear much of the low stuff in the mix with a band anyway (the bass player covers it), the "ideal" size and shape of the guitar amp's cabinet isn't nearly as critical as it would be for a stereo speaker. In other words, if you followed the formula, the cabinet would be overdesigned. It'd also be rather lifeless. The speakers, materials and style of construction are much more important than the size and shape. From what I've read, Marshall's cabinets were much more a function of aesthetics and manufacturing costs than of acoustic design.

8/8/2000 10:14 PM

Thanks guys.
I went back and used the parameters for one of webers marshall bulldog type speakers and got a cabinet 30" wide x 50" tall x 18' deep.

No No No

I've found the dimensions for a basic straight Marshall and will go on from there. I plan to use some speakers like the late 60's Marshalls so these measurements should be good. They are
29.25" tall
30" wide
14" deep

That should be all I need.

Thanks for the insight into the "pure" design neede for stereo speaker set ups. Guitar amps have never been close to being electronically correct(thank God) so I'm sure I'll be happy with what I build.

Thanks again, Firefly

8/12/2000 4:31 AM
Casey4s	Sean F, Thanks for your insight into this issue. I think sometimes as Guiter Players we tend to forget that this is NOT a stereo set up and that what is good for Hi End HiFi may not give the best tone for the buck in an amp cabinet. Casey4s

8/12/2000 5:15 PM

Hi-fi and instrument amplifiers are somewhat different in their design aims. A hifi is designed to reproduce a sound with as much fidelity to the original as possible. Instrument amps such as guitar amps are part of the instrument, and the non-linearities, distortions and resonances all contribute to give the characteristic tone of an amp/speaker combination. A guitar amp built to hi-fi spec would sound clean (obviously) and very lifeless and boring (if thats the right word), because it would lack the contribution of the amp to the sound of the guitar.

I'm fairly new to amp design, but I don't go on what should sound right, I just try it, and if I don't like what I hear I'll change it.

Just my meaningless waffle

Chris

8/12/2000 8:47 PM
Richie{~}==:::	The older Marshall cabnets and vintage cabs are taller..than the standard ones.. In speaker cabnets.. what they are made of and depth makes somewhat a difference..if its sealed or ported will effect the way the speaker sounds and works..just a few things to think about.. Richie{~}==:::

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