large v small drivers

[marec]

In the UK, rooms tend to be small and loudspeakers smaller still. For more than 30 years, my favoured loudspeakers have been tiny BBC monitors of limited loudness, but within their limits, a polite and perhaps accurate sound....
15 years ago at an audio show I came across some Cerwin Vega! speakers. The ! is merited.
For a short while I considered selling these for a living, but my wife soon disabused me. However the impact remained in my consciousness.
Since then, I have been increasingly convinced that larger drivers give more satisfaction (no sniggers please...)
I am interested to see whether the current MJK OB project produces something better than my previous OB project using 10" wharfedale + 15a.
I also have in mind a 2*15a + wharfedale (padded down as appropriate) and a 2*15a + 108ez padded down.
Any opinions on large v small drivers (driven within their limits?)

 

[AndrewT]

Hi,
my little AE1s go lower than my Tannoy Berkleys.
But the authority of the big Tannoy is completely missing from the Acoustic Energy.
I suspect that the little speaker simply runs out of SPL (at quite low listening levels) at the very low frequencies and although there is no audible distortion, the sound is "lacking".
Big seems to be beautiful where bass and sub-bass is concerned.

 

[marec]

Authority...
How might you characterise that?

I find a something almost subliminal from larger loudspeakers, but there is definately a tangible component

 

[Cal Weldon]

As simple as it sounds, IMHO the further you are from a driver the larger it needs to be. A 4" FR is fine in your bathroom or bedroom but won't cut it for a backyard party just as a 15" won't really reach it's potential in a bedroom and is often wasted unless you're creative with what that woofer is doing.


Is that along winded explanation of nearfield/farfield?

 

[Kensai]

Pioneer B20 8"ers are a class above Pioneer A11 4.5"ers, all around. Sure, the B20s either need a supertweet or EQ for their top end, but the top end of the A11 is too ragged and harsh to really be a selling point. Pretty much the only decent, direct comparison I can make at the moment, but I'd say larger drivers allow a more effortless sound and IMO that makes them more desirable. If I were to build an MJK like OB, I'd probably use my B20s + supertweet over my helper woofer(s).

Kensai

 

[Scottmoose]

Authority...
How might you characterise that?

The ability to shift a large quantity of air in the lower registers with little apparant effort. A smaller cone has to work commensurately harder (i.e greater excursion) than a large cone & it will never really be able to match it.

Naturally, a smaller driver fights back with (all other things being equal) cleaner & greater upward extension, break-up modes are easier to control etc. Ideal is to use large units to handle the LF, then either cross to something below our critical hearing region, or, if power-handling is important, at ~500Hz. You pick the driver to do the job.

The best FR (well, WR) unit I've heard to date in the LF is the Fostex FE208ESigma. Compared to every equivalent unit I know, including Lowthers, AERs etc., it has crushing air & weight & astonishing dynamic ability. As good as it gets until you shift to using dedicated bass drivers.

 

[marec]

Hi Scott;
Thanks for that. I guess that this is in some sort of resonant/ horn enclosure? From looking at the specs, I might guess that it generated more bass than a lowther, but I probably wouldn’t have expected the use of ‘crushing’…

However, currently I’m looking at OB’s with bass support. I’ve been really happy with the use of Eminence 15a’s in this role, both singly and in parallel, with passive and active x-overs and compensation.. The question boils down to: Do larger WR drivers sound better than smaller (as I suspect) and if so, why?

I have to say that ‘sounds better’ really means “something I am more comfortable with”, and as such may be down to an ignorant ear…

Mark

 

[el`Ol]

Sorry for not having an explaination, but I find the Beyma 8m70 looks like a promising wideranger for such a project.

 

[planet10]

Here are the contents of the answer to a similar question (use of a helper woofer brings a few other considerations*)

Choosing a FR means you have to choose your tradeoffs... i'll just tick off a general ones ...

1/ bigger drivers tend to be more efficient than little ones (which mean they play louder with a small amp)

2/ smaller drivers usually have better mids & tops.

3/ bigger drivers go lower & tend to be able to do dynamics better

4/ small drivers usually go in smaller boxes, with higher WAF, and lower cost to build

5/ bigger drivers tend to cost more (and i haven't meet a driver i can't improve)

6/ and a corollary to 5... a modded small driver for the price of a similar priced large driver will usually have more finese. (disclousure: i sell modded drivers)

With assistance in the bottom point 3 a is moot. With an OB 4a is also no longer a consideration. If you are trying to do a passive XO the extra efficiency of the larger drivers can be a hinderance.

That said i have Beta 15A and Fostex FF85K on the way for a MJK passive OB variant experiment (we'll play with active too)

dave

 

[marec]

Quote:
That said i have Beta 15A and Fostex FF85K on the way for a MJK passive OB variant experiment (we'll play with active too)

I'm getting to the stage where I'm happy with the sound from my MJK OB with passive 108 and 15a.

If I can raise the enthusiasm I'll bi-amp this with amps I have to hand (I built the passive x-over in split form).

If happy with this, I may go active with a behringer x-over before building something dedicated. I have to say, I'm quite enthused at the moment by these loudspeakers

Mark

 

[happy.gringo]

Mark,
Why did you decide to use the Beta this time instead of continuing with the Alpha?

 

[GM]

Authority...
How might you characterise that?

I find a something almost subliminal from larger loudspeakers, but there is definately a tangible component

Greets!

It's all about BW and acoustic efficiency. The CVs went lower with much greater acoustic efficiency. While our on-board computer apparently can reconstruct missing sub-harmonics, fundamentals from its harmonics, it's no substitute for the 'real deal' and the mids/HF sound more 'full'/extended when the missing tonally balanced LF BW is added even though there's no measurable difference in the mids/HF.

As acoustic efficiency rises, distortion for a given average/peak SPL falls and at some point the mids, tweeters are no longer pushed into any audible non-linearities and the top end opens up with more 'air' around the instruments with the only way to improve it at this point AFAIK is to increase the HF BW up to the 40+ kHz of some instrument's harmonics.

GM

 

[kristleifur]

Just to chime in: There's also the issue of directionality - larger drivers "beam" more, with a smaller sweet spot.

 

[GM]

Yes, this falls under the acoustic efficiency part.

 

[marec]

Quote:
Mark,
Why did you decide to use the Beta this time instead of continuing with the Alpha?

Actually I didn't. I quite like the Alpha's. It may have been Dave...

Rgds
Mark

 

[planet10]

Actually I didn't. I quite like the Alpha's. It may have been Dave...

no i'm using alpha... going to work on extending Martin's work. He didn't really do anything new, but the article catylized the entire genre and gives a simple recipe and greater understanding of how things work making it a lot easier for a lot more people to appreciate OBs and small FRs.

dave