Difference between 10" an 12" Speaker?

[warwickhunt]

[quote name='Mr. Foxen' post='1056201' date='Dec 12 2010, 04:57 PM']I'm talking in frequency bands though. Ported or sealed, I don't think there is much difference below 200hz (unless the sealed is seriously tiny and already rolling off by then). The cab material stuff, with flexing and suchlike is when it is acting as a pressure device, so is losing energy where that matters, which is low, but the stuff above that, aside from the out of phase reflection from a smooth surface, are down to the speakers own properties. This is what I am trying to confirm, with someone who actually knows. Maybe rephrase; 'what about a speaker enclosure affects the frequency response above 200hz, aside from internal reflections that are avoidable through lining?'.[/quote]

I see what you mean but surely the effect that a cab has on what you are hearing is inextricably linked to all of the factors and that must surely include those below 200hz (BTW I've no qualification in acoustics so I have no idea if the 200hz you quoted is an accurate figure )

However, (just thinking out loud) before we get embroiled in the effect of cab design on the tone of a given speaker... going back to the question of the difference between a 10" and a 12" speaker. Surely there are far too many variables between speaker manufacturers products to even worry about the affect on the 'low end' of extraneous factors such as cabs and their design. Not all 12" speakers are able to accurately reproduce a given sound never mind a 10" v 12" debate. Yes/No?

[LawrenceH]

[quote name='Mr. Foxen' post='1056201' date='Dec 12 2010, 04:57 PM']I know a the effect of a port is in a band about the tuning frequency of the port (not sure how wide, an octave or two?), and doens't do much outside of that to the sound, but the excursion below that band is increased beause the speaker acts like it is not in an enclosure.[/quote]

Actually pipe resonance well above the porting frequency can be a bit of a b****r to eliminate, one reason why designers might choose to put ports on the back of speakers. I'd also say 200 is a bit optimistic for what can be eliminated with lagging! Reduced maybe.
As for more esoteric cab designs, they can do all sorts of weird and wonderful things well above this frequency. Look at Bill's Jack 10s compared to the same Eminence driver in a ported cab, the mid-range response is massively different - one of the reasons he favours the Eminence drivers as their rising mid-range compensates to an extent for a drop in output from the horn.

[Captain Rumble]

Barefaced Compact does everything (nearly)
2 Barefaced Compacts does eveything (nearly) twice
No prizes for guessing what I use

[Mr. Foxen]

[quote name='LawrenceH' post='1056234' date='Dec 12 2010, 05:29 PM']Look at Bill's Jack 10s compared to the same Eminence driver in a ported cab, the mid-range response is massively different - one of the reasons he favours the Eminence drivers as their rising mid-range compensates to an extent for a drop in output from the horn.[/quote]

BFM's Jacks are horn loaded in the midrange though, if I'm picturing the right ones, exactly what I was thinking of when I mentioned in my question. Pretty good example of how a cab is acting in different ways at different frequency bands, they are horn loaded in the mids and act as a ported/direct radiator cab lower down as the horn is too short to contribute.

[Phil Starr]

[quote name='Bill Fitzmaurice' post='1051192' date='Dec 8 2010, 12:40 AM']The only factor purely attributable to cone size is dispersion. Everything else is based on driver specs. Well explained here:
[url="http://www.eminence.com/resources/data.asp"]http://www.eminence.com/resources/data.asp[/url][/quote]

This was a really useful link for those late to the debate and well worth a read if you are new to this. There's a table of the upper frequencies which can successfully be reproduced in the piston zone of a loudspeaker which interestingly shows even a 4" speaker can't really reproduce the upper hamonics of a bass without compromise. A good steer this.


[quote name='Mr. Foxen' post='1056163' date='Dec 12 2010, 04:27 PM']Can one of the experts confirm/disprove this?: the effect of the design of the box generally (unles you get horn loaded and suchlike) mostly affects 200hz and below, the mids are affected to an extend by the lining of the box and how reflective it is, but most of the upper stuff is down to the speaker's own properties. Which is why guitar speakers have their own sound since that low stuff isn't very relevant, but a bass cabinet is down to the box design relating to the speakers.[/quote]
Most of my design and development experience has been with hi-fi designs until recently. There are lots of ways (I won't even attempt to list them all) that a box affects the sound apart from the box volumes and tuning issues we deal with in Thiele/Small calculations. For example any sharp surface on the baffle will reflect/refract sound and this will be frequency dependant being affected by the size of the irregularity and the distance from the speaker. This is why high end hi-fi has the speakers set flush into the baffles. The biggest refractions are usually at the edges of the cabinets. Many cabs have the edges rounded to reduce this effect and speakers are often mounted off centre so that all this effect doesn't happen at a single frequency. Then there are panel resonances, as well as major resonances there may be minor harmonic resonances well above the 200Hz limit. Most bracing doesn't just reduce resonances but also raises their frequency. All of these things are quite audible in A/B testing because we are so sensitive to tiny differences to changes in sounds especially those we are familiar with, like human voices.

How important they are in instrument speakers is harder to judge. We listen to these sounds in usually dreadful acoustic environments with lots of other sound sources and at sound levels where our hearing becomes restricted by our bodies attempts to protect our hearing. In addition electric guitars and basses are entirely artificial sound sources, there isn't a 'right' or 'wrong' sound. Even a 'good' sound is entirely subjective. There is no doubt that the traditional square fronted 4x10 or 4x12 is all wrong for several reasons as far as fidelity is concerned and that the dispersal of higher frequencies is a total pain for the front of house engineer but if you like the sound then you have to work with this.

I think the answer to your question is that it is mainly right. The cab design is fundamental to the reproduction of low frequencies but above the 200Hz limit it is the character of the speaker which will determine most of the sound if you are dealing with a single drive unit. Multiple drive units will affect each other as described above. I'm assuming we are not talking about horn cabs here.