Audio experts help Decibel output.

While doing what you are proposing may increase the longevity of the amplifier, chances are you'll get less volume, not more, unless the amp is pretty much unable to function in a reasonable manner with the 4 ohm load.

Each of the series connected speakers would see half of the voltage that is being put out by the amp at any instant of time, resulting in each speaker receiving 1/4 of the amount of power that it would receive if the full output voltage of the amp at that instant were applied across it. So the total power delivered to both speakers (in each channel) would be only 1/2 as much as it would be if the full output voltage of the amp were applied across a single speaker.

The only way in which a volume increase would result is if the maximum output voltage that the amp can provide into 4 ohms (and that it can sustain, for some amount of time that depends on the kind of music you are listening to) is much less than what it can provide into 8 ohms, which would be indicative of a weak design.

I am assuming, btw, that you are referring to a solid state amp, not a tube amp.

Also, btw, keep in mind that for good sonic results series connected speakers should, in general, be identical models.

Regards,
-- Al

Yeah its just a basic cheapo mini amp for a car system. The speakers are all identical. I figure I'll try it as I planned, and if it actually is quieter I guess I'll just have to get a more powerful amp.

Thanks

Al, just a simple electronics question. I would think that a speaker has its own electronic attributes of resistance, reactance and inductance. So . . . would the characteristics of the signal coming off the amp be changed as it passes through the first speaker into the second? In other words, hooking two four ohms nominal rated speakers up in series isn't as simple as 2 times 4 equals 8. If it was, why not just stick a high power 4 ohm resister in series with just one speaker? Last point - a 30 watt amp is a pretty low power amp. If the OP winds up overdriving the amp, it may clip.

Would the characteristics of the signal coming off the amp be changed as it passes through the first speaker into the second? In other words, hooking two four ohms nominal rated speakers up in series isn't as simple as 2 times 4 equals 8.

Hi Bruce,

Yes, the signal seen by one speaker will be affected by the presence of the other speaker. However, if the two speakers are identical models, as I indicated they should be, their impedance vs. frequency characteristics will presumably match very closely. Given that, the effect will simply be that each of them will at any instant of time see a voltage equal to the output voltage of the amplifier at that instant divided by 2, which in turn will cause the amount of current flowing through them to also be divided by 2, relative to what it would have been without the other speaker being present. Since for a given load power is proportional to voltage x current, the two factors of 2 result in a four-fold reduction in the amount of power delivered to each speaker, as I had indicated.

Another consideration is the effect of the series connection on damping factor. Although it seems counter-intuitive, that is not an issue, as explained in this paper, which I must credit A'gon member Kijanki for calling to my attention a couple of years ago.

Why not just stick a high power 4 ohm resister in series with just one speaker?

That would waste half of the power being put out by the amp, since all of the power consumed by the resistor would be converted into heat, rather than some of it being converted into sound.

Last point - a 30 watt amp is a pretty low power amp. If the OP winds up overdriving the amp, it may clip.

Good point, especially of course if the speakers are relatively inefficient.

Best regards,
-- Al