6.5" vs 5.25" midrange woofer

[Walsh1]

Does one size have perks over the other? I've noticed that the M&Ks use 5.25" woofer and are very highly rated. I personally use the SVS Ultra bookshelf speakers for my left and right fronts but I like things I'm hearing about the RSL CG25 and CG5 series but they use a 5.25" woofer.

It doesn't seem like the smaller 5.25" is less superior simply because it is smaller.

 

[shadyJ]

It depends on how it's being used. A 5.25" can be used to higher frequencies before serious problems crop up, so if your tweeter doesn't play to midrange frequencies very well, a 5.25" can be better than a 6.5". A 6.5" does have more displacement potential, so, all other things being equal, it can have more dynamic range. A 5.25" can have a somewhat wider dispersion at higher frequencies, and that has to be considered in the design of the speaker.

I would say that you shouldn't try to form any strong opinions on a speaker based on the size of the diameter between those tow sizes. There is a lot of context that is needed beyond simple driver diameter.

 

[ryanosaur]

Performance will vary by driver. It is entirely possible for a smaller driver to out-perform a larger, even though in general terms, one might expect the larger driver to have slightlly lower extension and perhaps output. That is an oversimplification.
You really need to look at the specs for whatever you are shopping, and hope for some potential 3rd party testing to tell you how something is really performing.

 

[highfigh]

Some prefer to make speakers that sound close to 'good enough' without the sub, some make them so they need the sub for any listening. A 5.25" won't generally have a full lower mid or mid-bass, while many 6.5" do. My speakers have two 6.5" in a 2-1/2-way configuration and I haven't used a sub since I started using them over 5 years ago. Is it as full as it would be with a sub? Not with some music but for music that was mixed to have better mid-bass and extends smoothly to the upper-30Hz area, they don't really need one. The music that has weak bass just sounds like it's lacking bass.

 

[AcuDefTechGuy]

It doesn't seem like the smaller 5.25" is less superior simply because it is smaller.

Like ShadyJ says, assuming both speakers (6.5 vs 5.25) are equally well designed and built in every way, the 6.5" driver has the advantage of having more surface area than the 5.25" driver, which means more displacement, which means more DYNAMICS -being able to play louder with less distortion.

So in this example, the 6.5" driver could be superior to the 5.25" driver in terms of dynamics.

 

[Walsh1]

Like ShadyJ says, assuming both speakers (6.5 vs 5.25) are equally well designed and built in every way, the 6.5" driver has the advantage of having more surface area than the 5.25" driver, which means more displacement, which means more DYNAMICS -being able to play louder with less distortion.

This also raises another question. If have the crossover set at 80 htz and are running a subwoofer does that nullify the added dynamics to an extent anyhow?

 

[ryanosaur]

If have the crossover set at 80 htz and are running a subwoofer does that nullify the added dynamics to an extent anyhow?

Anecdotally, two speakers (each a 2-way design) designed by Dennis Murphy, with two different woofers, perform differently. Of course. When discussing the idea of transforming my Mini-Phil into a New-Phil because I wanted lower extension, he pointed out that the woofer in the one doesn’t perform as well up high and he has to cross it over much higher than preferred for the tweeter. His recommendation was to keep my Mini as is because it performs better at its xo frequency.

If have the crossover set at 80 htz and are running a subwoofer does that nullify the added dynamics to an extent anyhow?

If I follow your last question correctly... I was always under the impression f crossing the sub to speaker about an octave above the lower end of you speaker. So an 40Hz speaker should be crossed at 80. One at 60Hz should be crossed at 120. I have see recommendations to cross or 1/2 anoctave, too.
My advice is to be fluid and experiment. You need to protect your speaker, first, but also, you might find performance gains based on where you cross your sub at.

 

[KEW]

This also raises another question. If have the crossover set at 80 htz and are running a subwoofer does that nullify the added dynamics to an extent anyhow?

As a general rule, yes.
You would not be asking the 5.25" to do the particular thing that it lags behind the 6.5" (playing low and loud).

As has been said, there are lots of variables, but if the mid-woofers were of the same general design only scaled to a different size, you would presume the smaller driver would also be able to play higher frequencies without issues, so it might also allow a better match with a tweeter that needs to be crossed at a higher frequency for best performance.

Edit: Somewhat redundant post - I was typing when Ryan posted!

 

[AcuDefTechGuy]

This also raises another question. If have the crossover set at 80 htz and are running a subwoofer does that nullify the added dynamics to an extent anyhow?

I was really waiting for ShadyJ to answer that before I do.

But I’ll take a chance.

If we are talking about the MIDRANGE (500Hz-2kHz), and all things being equal (both the 6.5” and 5.25” midrange get the same subwoofer), then the 6.5” midrange still has more surface area, more displacement, and more DYNAMICS in the midrange (500Hz-2kHz) region.

 

[ryanosaur]

Edit: Somewhat redundant post - I was typing when Ryan posted!

That's alright, Shady and I posted simultaneously!

If we are talking about the MIDRANGE (500Hz-2kHz),and all things being equal (both the 6.5” and 5.25” midrange get the same subwoofer),then the 6.5” midrange still has more surface area, more displacement, and more DYNAMICS in the midrange (500Hz-2kHz) region.

I would add a cautious caution over this ... if driver sensitivity, and speaker sensitivity are considered, it is entirely possible to have the lower sensitivity larger driver completely outstripped by a higher sensitivity smaller driver, especially if the speaker as a whole is higher sensitivity. That might not always be the case, but worth considering!

 

[AcuDefTechGuy]

it is entirely possible to have the lower sensitivity larger driver completely outstripped by a higher sensitivity smaller driver, especially if the speaker as a whole is higher sensitivity.

That’s why we said “with all things being equal”.

We assume sensitivity, impedance, FR, measurements, etc., are equal for both speakers and drivers.

The ONLY difference would be the 6.5” vs 5.25” drivers.

 

[TheWarrior]

It all depends on the intended design, but general rule of thumb is to keep the wavelengths a driver is reproducing, to be LARGER than the diaphragm itself. This helps minimize the increase in directivity as wavelength gets smaller with increasing frequency.

 

[KEW]

That’s why we said “with all things being equal”.

We assume sensitivity, impedance, FR, measurements, etc., are equal for both speakers and drivers.

The ONLY difference would be the 6.5” vs 5.25” drivers.

If the FR and sensitivity of the speakers are equal that means that the 5.25 speaker would play as deep and achieve the same SPL as the 6.5" speaker! They would be identical in sound except for dispersion characteristics which you did not mention.
That is why I said "of the same general design only scaled to a different size"

One popular speaker about a decade ago was the Behringer Truth pro-audio monitor. IIRC, it was available with a 8" or a 6" woofer (2-way design). The general advice at the time was that if you were to use a subwoofer, avoid the 8" because the crossover to the tweeter was not as smooth. I don't know if was the beaming issue that TheWarrior is alluding to or that the 8" driver could not maintain a totally flat response up to the lowest frequency the tweeter could comfortably manage. It was not a bad sounding speaker by any means, but the smaller one had an advantage in the midrange!
That is not quite so likely to be an issue with a 6" driver as it is with an 8" driver (and probably why 8" 2-way speakers are not especially common). And, of course, there are always exceptions such as using a horn to allow the tweeter to comfortably play into lower frequencies.
For example the JBL 590 uses 8" mid-woofs and the horn tweeter allows it to crossover at a low 1500Hz!
The larger Klipsch towers are in the same boat for 8" drivers with low XO frequency!

 

[TheWarrior]

One popular speaker about a decade ago was the Behringer Truth pro-audio monitor. IIRC, it was available with a 8" or a 6" woofer (2-way design). The general advice at the time was that if you were to use a subwoofer, avoid the 8" because the crossover to the tweeter was not as smooth. I don't know if was the beaming issue that TheWarrior is alluding to or that the 8" driver could not maintain a totally flat response up to the lowest frequency the tweeter could comfortably manage. !

Probably both in that circumstance!

 

[shadyJ]

If the FR and sensitivity of the speakers are equal that means that the 5.25 speaker would play as deep and achieve the same SPL as the 6.5" speaker! They would be identical in sound except for dispersion characteristics which you did not mention.
That is why I said "of the same general design only scaled to a different size"

One popular speaker about a decade ago was the Behringer Truth pro-audio monitor. IIRC, it was available with a 8" or a 6" woofer (2-way design). The general advice at the time was that if you were to use a subwoofer, avoid the 8" because the crossover to the tweeter was not as smooth. I don't know if was the beaming issue that TheWarrior is alluding to or that the 8" driver could not maintain a totally flat response up to the lowest frequency the tweeter could comfortably manage. It was not a bad sounding speaker by any means, but the smaller one had an advantage in the midrange!
That is not quite so likely to be an issue with a 6" driver as it is with an 8" driver (and probably why 8" 2-way speakers are not especially common). And, of course, there are always exceptions such as using a horn to allow the tweeter to comfortably play into lower frequencies.
For example the JBL 590 uses 8" mid-woofs and the horn tweeter allows it to crossover at a low 1500Hz!
The larger Klipsch towers are in the same boat for 8" drivers with low XO frequency!

I have measured the 2031P Truth Monitors, the directivity is well matched. Here are some graphs:

 

[KEW]

I have measured the 2031P Truth Monitors, the directivity is well matched. Here are some graphs:
View attachment 29885
View attachment 29886
View attachment 29887

That's one, I forgot it was a 8.75-in woofer!
So it looks like maybe the word that the 2030's we're better through the xo range was/is unfounded?

 

[shadyJ]

That's one, I forgot it was a 8.75-in woofer!
So it looks like maybe the word that the 2030's we're better through the xo range was/is unfounded?

The 2030p might have better directivity control, I don't know about that one, all I can say is that the 2031p is not bad at all. If you squint you can see a slight narrowing around the crossover point at 2 kHz, but I doubt that would be audible at all. It could be that the polypropylene cone helps to alleviate beaming and breakup modes.

Back in the day, you could sometimes get these for as low as 120$ each, which made them an absolute bargain.

 

[KEW]

The 2030p might have better directivity control, I don't know about that one, all I can say is that the 2031p is not bad at all. If you squint you can see a slight narrowing around the crossover point at 2 kHz, but I doubt that would be audible at all. It could be that the polypropylene cone helps to alleviate beaming and breakup modes.

Back in the day, you could sometimes get these for as low as 120$ each, which made them an absolute bargain.

Thanks for that. I had a pair and they always sounded fine to me. I just figured if I had the 2030's to compare, then I would hear the difference!

 

[3db]

It depends on the size of the room that the speakers are ging to be playing in. Take my primary setup in my town house as an example. I cannot crank the sound like I used when I lived in a 4 bedroom single family home. I will not even come close to the limits of my PSB Image T45s which use dual 5.25" drivers in a 2.5 way design. The bass is great for most music I listen too with the exception of pipe organ music. The T45s are rated at 35-23,000Hz +/- 3db and 48-20,000Hz +/-1db on axes. The T55s are rated 32 and 45Hz respectively using the 6.5" driver snd larger volume cabinet.