How important are Cab Dimensions?>

DrGonzo

Hello again!

Just wondering, I am thinking about building (well more like getting built for me ?) a new Closed back 2x12 cabinet.

how important are the cabinet dimensions in terms of the sound?
I assume bigger cabinet means more bass? Is there such thing as a cabinet that is "tuned"? I believe I may have heard that term...

So can anyone recommend me a good set of cab dimensions that will have a tight and even frequency response? and sound big!
I dont want the cab to be too big though...

Also does the type of wood make a difference?

Help will be appreciated as always!

Gearhead

There is no such thing as the right cab dimensions for any driver (speaker). If you go for closed back, the air inside the cab starts to act as a spring and a bit of a damper. Together with the springyness of the cone suspension, its damping and the cone+coil mass, this thing acts as one mechanically. If you then add the electrical parameters of the amp plus the wiring plus the filtering (if any) plus the coil, you get the whole picture. Since speakers differ greatly in their electrical and mechanical properties, cabs that go with them also differ.
Yes you are right that bigger means it will be more suited for a speaker with low resonant frequency. However, the cab cannot make a driver 'go lower' and the bigger the cab, the looser the bass as well. Yes you are right that a small cabinet can restrict the bass response of a speaker. However, I have heard 25 liter driver/cab combinations push out 50hz with far better efficiency than the 80liter system right next to it.
Bottom line (and I have posted this before) is that if you know the so called TS parameters of the speaker you want, it is a relatively quick job to simulate the right cab with it to within 5% accuracy.

flatfourfan

I used to build speaker boxes for night clubs as well as tonnes for car audio and it's basically the same principal. I've made a full stack for a client a while back and it's great. I used the specs for the marshall models (can't think of the model right off my head, but it's on my for sale thread).

I got the dimensions off the net. I built his full stack with a removable panels as the guy wanted to try a few cabinet options. I was used to making car audio boxes, but they are usually built from MDF and that's nice and dense, but the boxes never get moved, so I don't know how they would hold upto being moved and bashed all the time. My 4 x4 12" and 10" half stack is about 550mm x 550mm x 450mm. Very rough sizing. The more dense the wood, the more solid the sound, I built a temporary box out of some cruddy pine and you could hear the difference, it sounded very tinny.

I build my sealed boxes per spec and build per the speaker.

Norman86

those so called ts parameters are very important in determining your speaker enclosure!
Its exactly how high end audio speaker cabinets are developed and built! And most others too...
You can tune the box, but you will need the speakers parameters to do so!

flatfourfan

ps, check out this site. Great info. I used it a lot for specs.

http://music-electronics-forum.com/f24-1/

DrGonzo

Gearhead wrote: There is no such thing as the right cab dimensions for any driver (speaker). If you go for closed back, the air inside the cab starts to act as a spring and a bit of a damper. Together with the springyness of the cone suspension, its damping and the cone+coil mass, this thing acts as one mechanically. If you then add the electrical parameters of the amp plus the wiring plus the filtering (if any) plus the coil, you get the whole picture. Since speakers differ greatly in their electrical and mechanical properties, cabs that go with them also differ.
Yes you are right that bigger means it will be more suited for a speaker with low resonant frequency. However, the cab cannot make a driver 'go lower' and the bigger the cab, the looser the bass as well. Yes you are right that a small cabinet can restrict the bass response of a speaker. However, I have heard 25 liter driver/cab combinations push out 50hz with far better efficiency than the 80liter system right next to it.
Bottom line (and I have posted this before) is that if you know the so called TS parameters of the speaker you want, it is a relatively quick job to simulate the right cab with it to within 5% accuracy.

Cool, well, the speakers are Vintage 30's.... Im not sure if you know the parameters of that speaker?

Im thinking maybe i should just clone a 2x12 cab that uses vintage 30's like a mesa roadster or rectifier cab. Im pretty sure they put some thought into the dimensions!!

Norman86

I dont like Celstion for the following reason, they dont include their TS parameters or view them as important.

i quote:

Celestion wrote:THIELE SMALL PARAMETERS
Thiele Small parameters are useful for controlling the low frequency response of sealed or ported cabinet systems by changing the cabinet internal volume, and port dimensions. They have no relevance to open back cabinets, and guitar speakers are not recommended for use in ported cabinets (as the increase in cone excursion below the tuning frequency can cause the thin paper edge of the cone to tear), so this only leaves sealed or 'closed back' cabinets. However, electric guitar speakers do not reproduce 'low' frequencies (the low E string of a lead guitar has a fundamental of 82Hz) and so the frequencies at which Thiele Small parameters have significance are mostly below the operating range. Also, the parameters are measured at very small signal levels. Guitar speakers become non linear at very low levels compared to other types of speaker, greatly reducing the significance of Thiele Small parameters in actual speaker use. Using the Thiele Small parameters of a typical guitar speaker, you will find that halving or doubling the cabinet size makes minimal difference to the response. The cabinet size, shape and construction are of far higher significance than the internal volume. Cabinet design using Thiele Small parameters ignores these most fundamental aspects. Important factors include the material you make the cabinet from, the panel sizes and shapes, how they are joined, how the cabinet is finished, the mounting of the speaker, etc. These, not Thiele Small parameters are the critical factors in the design and ultimately the sound of a guitar speaker cabinet.

But if you read that, they talk about size of the enclosure...
Now how the hell are you supposed to design an enclosure or know the size of the enclosure, without the TS parameters?!?!?!

If you make it too big, you're going to lose bottom end, but also over exert the speaker and end up with mechanical failure!!!!
too small, and then the cabinet colours the sound of the speaker, overemphasizing the wrong frequencies!

If you're designing an open back cab, well then this has no relevance... but if you want a closed back cab, it has all the relevance!!!

DrGonzo wrote:
Cool, well, the speakers are Vintage 30's.... Im not sure if you know the parameters of that speaker?

Im thinking maybe i should just clone a 2x12 cab that uses vintage 30's like a mesa roadster or rectifier cab. Im pretty sure they put some thought into the dimensions!!

That will probably be best yes!

Gearhead

They are right about using open back cabs ?

djpauw

I used to build high-end hifi/home theatre speakers some years ago... Make no mistake, the dimensions and design of a speaker enclosure makes a hell of a difference.

To be honest, you can slap anything together and it will WORK, but for the best results it is definitely worth doing a proper design.

Do a search on Google, there are many sites with good info and also some very nice freeware apps and spreadsheets to help you calculate the best size etc.

On a little more technical note, the main thing you want to avoid is a perfectly square box or similar because this will cause resonance at certain frequencies....

Just my 2c, peace out

DrGonzo

thanks for da info! Much appreciated ?

Malkav

If you're gonna steal a design for a cab rather go with the Orange 2x12, they are amazing. I think they're actually a bit nicer than the Mesas for modern metal and are one of the only cabs out there that can take a beating from a 7 or 8 string guitar and still stand up well. The only issue is that they weigh a metric f*** ton...