And Now For Something REALLY BIG

[Cal Weldon]

Cone break-up?

[IG81]

Originally Posted by JRKO

Can anyone explain the virtues of picking a smaller mid driver than a 10 incher. I can't seem to understand the issues involved

The larger driver will start to beam lower. (Pano beat me to it ) IIRC from my measurements, the TF1020 had good 60° dispersion up to ~1.5kHz. An 8" driver might make it a bit higher, if wide and even dispersion is a goal of this project, but otherwise, TF1020 makes it to ~2.5kHz before its first breakup, so you'd be good for your 200Hz-2kHz range with it.

IG

[JRKO]

ok - 'beaming' - is that where the driver, at a certain freq. and above, becomes more & more directional thus narrowing the 'sweetspot'?

Cal the Connoseur , with cone break-up you've thrown another hat into the ring. To my sadly lacking mental faculty, I would have though that means the cone distorting at lower freq.?

[IG81]

Originally Posted by JRKO

ok - 'beaming' - is that where the driver, at a certain freq. and above, becomes more & more directional thus narrowing the 'sweetspot'?

Cal the Connoseur , with cone break-up you've thrown another hat into the ring. To my sadly lacking mental faculty, I would have though that means the cone distorting at lower freq.?

Yes, beaming is the reduction in dispersion angle as the wavelenghts get smaller than the cone diameter. It's a bit the same principle for breakup AFAIK, in the sense that when the wavelenghts get smaller than the cone radius, the cone is not moving in unison, aka pistonic movement. This will happen with all drivers, it's just that some will do it more gracefully and barely exhibit a thing on their response, while others will get large peaks and dips.

IG

[tinitus]

Originally Posted by Pano

The Alpha 6 is "OK", but not the driver that the Beta 8 is.

just of general interest, the 8ohm 6A, or 4ohm 6C ?

at least on paper they appear to measure differently
around here I have only seen the 8ohm 6A in OB

[JRKO]

Aha - so where the TF1020 freq response get ragged just over 2khz this is breakup as the cone is used to produce freq. smaller than its diameter and thus outside its ideal 'zone'?

Breakup and beaming are separate issues but are both results of the freq. wavelength being smaller than the cones diameter and thus ending pure pistonic motion

So as long as the driver is used within the smoothest part of the freq. response graph it should be fine.

Is there a list somewhere of wavelength 'sizes'? What specs will show the drivers dispersion? I'm slowly making my way thru Controlled vs wide dispersion in a normal living room environment..

The 8 inch driver seems like a good idea being smaller and in the Alpha8 really clean but the TF1020 looks like it can handle 2khz just fine and would push more air

[IG81]

Originally Posted by JRKO

Aha - so where the TF1020 freq response get ragged just over 2khz this is breakup as the cone is used to produce freq. smaller than its diameter and thus outside its ideal 'zone'?

Breakup and beaming are separate issues but are both results of the freq. wavelength being smaller than the cones diameter and thus ending pure pistonic motion

So as long as the driver is used within the smoothest part of the freq. response graph it should be fine.

Is there a list somewhere of wavelength 'sizes'? What specs will show the drivers dispersion? I'm slowly making my way thru Controlled vs wide dispersion in a normal living room environment..

The 8 inch driver seems like a good idea being smaller and in the Alpha8 really clean but the TF1020 looks like it can handle 2khz just fine and would push more air

At least this is how I understand it to work - there are folks way more knowledgeable than me who are welcome to correct any idiocies that I may spit out!

wavelenght = speed of sound divided by frequency. For c=343m/s and 1kHz, 343/1000=34.3cm, for example.

I bought my TF1020 based on the low sale price at the time and this guy's (stevie) comment on it, no direct test results, so has to be taken FWIW:

http://forum.speakerplans.com/celest...73.html#354373

IG

[tinitus]

Originally Posted by JRKO

Cal the Connoseur , with cone break-up you've thrown another hat into the ring.

then it might be time to throw in another hat...BSC

[IG81]

Originally Posted by tinitus

then it might be time to throw in another hat...BSC

Assuming an active Xover and a large-*** enclosure as this might result in, BSC might be a non-issue.

IG

[JRKO]

Oh great

The great and mystical Baffle Step Correction

How does that work on these very wide speakers? Wide is good right? (gets hit by wife )