I have a TOA 301 15W amp and a Bose 151 environmental speaker(40w 4 ohms). I do not have a manual for the amp and wish to connect the speaker as a small PA . My concern is that the output I think I should connect to is marked is marked 4 ohms 7.7V. Is this the correct output?? I know I should not be using the 100v or 70 v line outputs Thanks Robert Lewis

You need to check both the Ohms range of both devices, plus the output power of them too.
The ohms range is the most crucial. For example if the amp will only go down to 8 ohms, you cannot connect speakers lower than that. No speaker must have an ohms rating lower than your amp. Higher doesn't matter.
Many amps have a range on them say 4 to 16 ohms. But the crucial one is the smaller figure.

The power output is less problematic. For example if the amp is 30 watts per channel, then you should connect a speaker of at least that, or more. But you could still connect say 25 watt speakers. However you MUST NEVER turn up to full volume or you will blow the speakers!

it is load resistance. set the amplifier switch to the resistance ( X amount ohms) to match your speakers. Although running 4 ohm speakers at the 8 ohm setting is louder, it will hurt your amp
most home/semi pro speakers are 8 ohm, while car speakers are 4 ohm. If you are doing a multi speaker pa/intercom install use your formula to calculate total load is 2 8 ohm speakers in parallel are four ohms . express them as fractions and add the denominator ie:8/1 +8/1 = 8/2 or 4/1 or 4. now connect that in series (add the top numbers)with another 2 speakers in parallel and you get back to 8 ohm load. repeat the same process over and over and you can hook up to 32 speakers to the amp without needing the 70 volt tap. hope this helped.

You weren't by chance connecting a powered subwoofer to the standard speaker channels? Most powered subs require a dedicated output from the amp, otherwise you would be amplifying the signal twice over!

yes! the specs look good, in fact the amplifier output matches the speakers, plus the ohms ratio is fine.

You will be ok. The ohms on the unit are for the rca jacks for an amp. your only issue would be if you have really crappy factory speakers that peak at less than 20-30w. If you have am speakers then your fine with almost any head unit.

How many ohms is your sub? The SA 3 Amp can only handle speaker(s) 6 ohms and greater. A lot of subs, as I understand, are 2 and 4 ohms typically. If yours is 2 or 4 ohms, then that explains it. The speaker would be "straining" your amplifier and blowing it.

two 8 ohm speakers in parallel is 4 ohms.
if series 16 ohms.a high resistance will just produce less power.
too low a number can activate the speaker protect,or blow the amp.
radio shack sell wall mounted speaker controls,but 5 watt max.
the best thing is to run 2 amplifiers.one for in ,2 for out
speaker a and b on the amp parallel the speakers.
if you run 2 sets of 4ohm speakers,the amplifier load will be 2 ohms,and overheat the amp.4 8 ohm speakers,gives a 4 ohm load

Hi

I checked in the specs of the manual here. page 6. They quote it as being suitable for 4-8 ohm AMPLIFIERS. but do not mention the actual impedance. I would expect from that that the speakers must be close to 8 ohms, as you they would not advise you to connect a 4 ohm speaker to an 8 ohm output stage, as likely damage could result. If you had a multi meter, you could do a DC resistance check of the speaker, this is generally very close to the impedance. happy to talk to you more about it.

regards
robotek

Unfortunately many speakers do not have fuses. Most likely the voice coil has opened up inside the speaker itself. You can either get a replacement driver (speaker) or re-cone the one you have. In any case, the driver needs to be replaced.

You can verify this if you use an ohmmeter. With an 8 ohm impedence speaker, the reading should be about 6 ohms. If you read a higher number or infinity, the coil is bad.

Dan

http://www.toaelectronics.com/Manuals/P-906_12_24MK2.pdf.