A restaurant has 4, full range, 8ohm sealed speakers attached to a stereo amplifier. (2 on each channel). Against my advice the owner paid me to install a passive subwoofer. (6 ohms).
Here's the thing . . . The full-range speakers bottom out at 100hz (I'll assume Fs is around that frequency). The sub has an Fs of 50Hz.
Will the differing frequencies of high impedance offer any protection?
I did the job. I told him I was not responsible, and not to turn it more than 1/3 of the way up.
I know 4 caps would negate the danger but he doesn't want to pay the extra.
Ironically, there's an abundant cheap solution for this kind of installation.
Here's the thing . . . The full-range speakers bottom out at 100hz (I'll assume Fs is around that frequency). The sub has an Fs of 50Hz.
Will the differing frequencies of high impedance offer any protection?
I did the job. I told him I was not responsible, and not to turn it more than 1/3 of the way up.
I know 4 caps would negate the danger but he doesn't want to pay the extra.
Ironically, there's an abundant cheap solution for this kind of installation.
Hi, if you wire in series the two speakers in each channel, the amplifier would deliver less power each, so no bottoming. The woofer (+ it's passive crossover) will be attached to one channel and total Z would be acceptable.
I don't think you supply enough info to really address your concern. It will be about how you connected it, how the tops impedance trace and the subwoofers impedance trace look like...
And its not 6+6+8 it's 6 // 6 // 8 -> which "adds" to ... 2,3 ohms but if the tops happened to be say 5 ohm and the sub 4 at one and the same frequency -> 1,5 ohm - add some nasty reactive aspects and you have a fire 😉 ... maybe..
//
And its not 6+6+8 it's 6 // 6 // 8 -> which "adds" to ... 2,3 ohms but if the tops happened to be say 5 ohm and the sub 4 at one and the same frequency -> 1,5 ohm - add some nasty reactive aspects and you have a fire 😉 ... maybe..
//
Wire all the 8 ohm speakers series parallel, & drive them with one channel. Drive the sub with the other.
The cheap b'strd doesn't deserve stereo...
The cheap b'strd doesn't deserve stereo...
No.
e.g.
I can treat & paint your wall for £500 - that's what it needs.
Just painting is £100 but the damp will return very quickly.
Fs is the drivers free air impedance peak, it rises to Fc in a sealed cabinet.
In a ported cabinet, the Fb (box tuning frequency) is surrounded by two impedance peaks.
You are wasting your time guessing what the impedance of the restaurant speakers are.
If you series the top speakers they would get a fraction of the power they get wired in parallel, so their excursion and level would be far less.
For a few $ you could add a series cap on the left and right to cut the bass from the tops, no need for four.
Resistors in parallel add up by taking the inverse of each resistance, summing all of those, and then taking the inverse of that number. E.g.
resistor 1 = 8 Ohms, the inverse is 1/8
resistor 2 = 8 Ohms, the inverse is 1/8
resistor 3 = 6 Ohms, the inverse is 1/6
Add these: 1/8 + 1/8 + 1/6 = 0.41666
Finally, take the inverse of that to get the overall resistance when all three are in parallel:
1/0.41666 = 2.4 Ohms
resistor 1 = 8 Ohms, the inverse is 1/8
resistor 2 = 8 Ohms, the inverse is 1/8
resistor 3 = 6 Ohms, the inverse is 1/6
Add these: 1/8 + 1/8 + 1/6 = 0.41666
Finally, take the inverse of that to get the overall resistance when all three are in parallel:
1/0.41666 = 2.4 Ohms