drivers without specifications

[aldus]

I have 3 pairs of drivers. Tweeter, midrange and woofer. And I want to build a pair of loudspeakers with them. Each one has an impedance of 8ohm. The problem is that the only parameter that I have is driver's impedance. Nothing more.

Some posts explain how to measure Thiele/Small parameters; however, I don't know how to measure the speakers frequency response. Any Idea?
Thanks,

Aldus

[5th element]

Change the 'I don't know' part about measuring frequency responses into, 'I can now'. And you're sorted. There's lots of stuff out there explaining how to go about doing this. I highly recommend using the ARTA measurement package for this too.

Technically speaking you will only need good T/S parameters for the woofer. The tweeter doesn't need a box and if the mid does then putting it into a 3-5 litre chamber, inside the main cabinet, will most likely be fine. In almost all cases you tailor the mid range drivers lower end roll off with the crossover anyway, so it's actual response in the cabinet is somewhat unimportant.

So for all intents and purposes you need the impedance and frequency response measurements of the tweeter, mid and bass drivers in the cabinets they intended to be used in and to measure the T/S parameters of the woofer before designing the cabinets main volume.

[Kal Rubinson]

Also, post some pix. Somebody might recognize them.

[aldus]

Thank you very much. Your post explains a lot. I will follow your recommedations and buy ARTA. I noticed that ARTA is cheaper that LSpcad + JustMLS.

Concerning your guidelines, wolud you post a picture or a draw of the chamber inside a cabinet? It would be useful.

[5th element]

ARTA is actually free for the most part, you can still export the files necessary for crossover design without paying for it. What paying gets you is the ability to save, which also has its uses. But do play around with the free version of ARTA first, just to check that the way it works fits well with you.

ARTA and LspCAD are two separate things. ARTA is a measurement package, LspCAD is a software simulation package for the design of loudspeakers and their associated filters. You need both of these to design a loudspeaker, it's just that LspCAD comes along with JustMLS to give you a way of making measurements.

I use LspCAD for loudspeaker design and ARTA for making my measurements.

If you want to experiment with a free loudspeaker design package there is the stuff that the FRD consortium makes (spread sheets) and Speaker Workshop.

Actually this website is pretty useful.

http://www.rjbaudio.com/Audiofiles/FRDtools.html

As to the chamber inside the main cabinet - this is really just a cabinet within a cabinet, it isn't anything special It's just of a specified volume (if necessary), in this case I recommended 3-5 litres, and is completely sealed off from the main cabinets volume so that the pressure changes within the main cabinet, created by the bass driver, don't affect the mid.

[aldus]

Thank you again. I will put into practice your recommendations.