16 ohm drivers

Brett

Member
2002-01-07 6:02 pm
Alnico magnets are inherently self shielding, and so have much lower stray fields. Ceramic and neodymium mags are not. Some of my compression drivers will distort my TV from a couple of feet away, yet my alnico Tannoys don't.

Adding a series resistor will reduce the level to the driver, and probably change the tuning of any crossovers and low frequency tuning unless compensated for.
 
Double M Cups

Pat O'brien
http://www.warco.com.au/awar.htm
used to stock a range of sizes of heavy guage steel, powder coated metal "cup" to fit over the back of, and enclose the magnet assembly for the pupose of magnetic shielding.

I am not sure if he still stocks them, but you've got the link above.

Also take a look at the drivers in typical modern AV systems and televisions - They typically use the cheapest cup shaped pressing you can find.
Others have an additional ferrite ring glued to the back of the magnet assembly.

It should not be too difficult to cook up something suitable.

Regards, Eric.
 

Electro

Member
2002-04-12 4:41 am
Add a resistor to get your impedance up.
I would not because adding a resistor increase the Qes of the speaker driver and it decreases the SPL too.


markkanof, your best bet is to find dual voice woofers and hook their coils in series. This will not change the Qes too much because the wire used is a bigger diameter or lower gauge value. Next find a magnet called a bucking magnet. You can find bucking magnets at Parts Express, Madisound, etc. After you mount (on the back plating) the bucking magnet to the woofer, I suggest you measure the woofer.
 
Perhaps a little out in left field for your ap but i'm on a push-push kick right now.

If you take two drivers and mount them magnet to magnet you get a push-push bi-polar driver that is pretty well shielded. Wire a pr of 8s in series and you have 16 ohms. I took a pr of RS 40-1197s and i could get them within a couple inches of the monitor before it started going blooey. With one driver by itself maybe 18".

As mentioned earlier alnicos are inherently shielded. Your best source for these are the 2nd hand stores (either directly or from those of us scouring those stores for you and flogging them on eBay.

dave
 
Hi !
Based on your description, you should look at GR-Research. The GR-165 is a 16 ohms, 6.5" and it's shielded. That's what's inside their A/V 3 kit which is a MTM with a series XO. It has good sonic reputation. You can buy the drivers separately and the price is good. They don't sell bigger driver though. They're being made by Peerless-India to their specifications.

http://www.gr-research.com/drivers.html#gr165

Good Luck
 
"adding a resistor increase the Qes of the speaker driver and it decreases the SPL to

Using Qes to tune Qts.

An observation using Unibox Software

A change in the voice coil Re does not effect Qts yet really drops Spl

If I raise Qes (driver Re at Fs) the Qts goes up to a very nice .38
and SPL drops by 1 db, mostly in the midrange leaving the bass intact.
Is the driver Re linked to Voice coil Re and Qms

Just changing the Qes is an ideal situation for this Eminence Pro driver. Can I do this ??


Power Applied 50W
Fs 38.2
Re 5.0 Ohm
Qms 7.73
Qes 0.32
Sd 858.0
Vas299.0L
Xmax 5.5mm

SPL at 1 W 1 m 99.1 db
SPL at 2.83 Vrms 1m 101.1 db
Qts 0.307
Effective Qts 0.307
Mms 60.03g
Cms 0.289mm/N
Rms 1.864 Kg/s
Bl 15.00Tm
Ref efficiency, n 5.007%
Applied voltage 15.81 Vrms
========================

Now with a change to Qes of .40

SPL at 1 W 1 m 98.1 db
SPL at 2.83 Vrms 1m 100.2 db
Qts 0.38
Effective Qts 0.38
Mms 60.03g
Cms 0.289mm/N
Rms 1.864 Kg/s
Bl 13.42Tm
Ref efficiency, n 4.006%
Applied voltage 15.81 Vrms


I can post a jpg of Parameters or SPL plot, just ask TIA