6 1/2" Vs 8" mid/bass for a 2 way speaker

[Bricolo]

Hi all

As you probably know, I want to build a 2 way speaker for my gainclone amp (60W in 4R)

It will be a floorstander, 2 way, with a transmission line (audible bass down to 40-50Hz is what I want)

Most of the 2 way designs I've seen are using a 6 1/2" (170mm) midbass, some others use a 8" (210mm)



Can somebody tell me which size would be the most suitable for my project?


thanks
Alex

[MJK]

Hi Bricolo,

I have used both sizes and prefer eight inch drivers. They move more air leading to a better low bass response with lower cone displacements.

Just my experience,

[Battlepriest]

With rising frequency, the wavelength decreases. When it comes down to the meassurements of the cone the dispersion gets worse. Here are Diagrams, that show the dispersion of a 17cm and a 20cm woofer with alucone at 2000Hz which is a common XO frequency. I copied them from the german Visaton website.





As you can see, even the dispersion of the 17cm driver is already limited. Remind, that in most cases, you won't sit in the nearfield of your speakers and you will hear lots of reflections. so, the 17cm seem to be the best compromise between bass ans dispersion.

[Salas]

Hello,

The 6,5'' is arguably a wise solution. But I always had excellent results when I used an 8'' with 1500Hz cross. The only thing is you have to combine a tweeter with 600-800Hz resonance.
That way you get the best of both worlds.
Recently I made a speaker using the smooth & inexpensive Audax HP210G0 and Morel MDT 30 (32s is the current equivalent). Very good sensitivity, bass and dispersion. Very good Zin also.
Here is the biwire cross schematic.

Regards

Nikos

[jim]

Hi Nikos,

Recently I made a speaker using the smooth & inexpensive Audax HP210G0 and Morel MDT 30 (32s is the current equivalent). Very good sensitivity, bass and dispersion.

Could you tell us some details of this speaker ? (pictures, enclosure design) I'm looking for a speaker design with good sensitivity for my tube amplifier.

Thanks,
Jim

[Brett]

Why not a 6" 2 way standmount and a TL sub with a decent > 12" driver, crossed in below 100Hz. It'll sound a lot better than trying to get a little driver to do bass, or a larger driver with it's dispersion problems. And you can biamp; below 100Hz the amp is much less audible so you could pick up a second hand SS amp of suitable power quite cheaply and use that for the bass.

For example, look at Chris Brady's system; Ariels with TL subs.

[navin]

Originally posted by salas
The 6,5'' is arguably a wise solution. But I always had excellent results when I used an 8'' with 1500Hz cross. The only thing is you have to combine a tweeter with 600-800Hz resonance.

yes you can do this I did this 22 using a MDT33 and teh Focal 8N515 (in 1988). In fact I used 2 8N515. with 2 x 8" for most installations you wont need a sub. for HT however a sub is imperitive.

good quality bass requires very large boxes if you want to go below 40Hz or so. in fact even at 40-45Hz the boxes get pretty big (2.5 cu. ft +).

For most music very low bass in the main speakers excites room nodes and this detracts from the music. dipoles are an excepttion but then you have to move a lot of air using dipoles.

one way out is to use 2 x 6-8" woofers (this depnds on the tweeter you got etc..) and then use a sub below 40Hz in a corner which is used only in HT mode.

what woofers / tweeter are u considering?