Don Pearce wrote:
On Sun, 08 Apr 2012 16:46:17 +0100, Jim Lesurf
wrote:

In article , TonyL
wrote:
Arny Krueger wrote:

At some point, measuring T/S parameters starts looking good.


Better than building 3 boxes, certainly.

I don't know about the UK, but in the states you can get a USB
gizmo with software that does full relevant set of driver tests
using your PC for under $100.


OK, but that would be somewhat more than I paid for the drivers. I
do have an amp module that goes down to DC as well as other bits of
audio gear so I might have a go at T/S parameters to give me a
ballpark figure for the box volume.

Someone else will know the details rather better than myself. But I
think you can estimate some of the basic parameters for a large bass
speaker from some quite simple measurements.

e.g. By using a ruler to measure the displacement of the speaker
cone when you apply a fixed dc voltage. And - with the speaker
pointing upwards - how much displacement a small weight produces.
(Rotating from vertical to horizontal and measuring the displacement
will also let you estimate the mass of the cone, etc.) None of that
may be very accurate, but may still be close enough.

IIRC The "Loudspeaker Design Cookbook" by Vance Dickason explains
this in an appendix. But I may have actually read the details
somewhere else. Not really my topic.

Slainte,

Jim

I've found a very good explanatory web page which describes in fair
detail how to measure the T/S parameters. There is a downloadable
spread sheet to put the measurements in and produce a full T/S
parameter set.

http://sound.westhost.com/tsp.htm

I've fed some dummy data in, and the answers are very believable.


Thanks all. I'll drag one of the units from the loft and try the T/S 'added
mass' measurement method, not having a ready made box yet.

Great site, BTW.

Anybody like to comment on how T/S params translate to box volume if I tried
an isobaric design as mentioned by Phil? Just divide enclosure volume by 2?