Parrellel?

[bhg41088]

If i have 2 of the same speakers, both 88db/1w and both 8 ohm, and i wire them in parrellel, it is a 4ohm 91db/1w load, and 4 of them in parrellel makes a 2ohm 94db/1w load, right? Sorry, i cant find this when i search.

[johninCR]

Yes, doubling the drivers or speakers gives you 3db more output, however, in general, halving the impeadance will double the amplifier output. If your amp can handle the 4ohm load then you'd go from 88db to 94db with 2 because it would be 2 watts (one to each speaker), so you've added 3db with the other speaker AND doubled the power to 2 watts.

[BillFitzmaurice]

Wen you parallel wire two identical drivers/speakers you get an increased voltage sensitivity of 6dB. You get 3dB via the doubling of the radiating area, which doubles the radiating efficiency, and you get 3dB via the halving of the impedance, which doubles the amps output wattage for the same voltage output. However, you are also doubling the current draw from the amp; if the impedance goes low enough the increased amperage draw will overload the amps output devices and power supply and failure will result.

Parallel wiring will result in a 3dB increase of wattage sensitivity, all of it being derived from the increase in radiation efficiency, as maintaining a level wattage output from the amp when halving the impedance load requires reducing the output voltage by 3dB.

If you series wire two identical drivers/speakers the impedance doubles, the current draw halves, so the wattage for a given voltage is cut in half, for a loss of 3dB. However, this is offset by the doubling of radiating area, so net voltage sensitivity remains the same.

[Kittle]

ok so assuming your amp can handle the increased load.. is parallel wiring overall a good thing? or overall a bad thing?

The reason I ask, is I have 2 identical drivers im looking at wiring in parallell as well. They are rated at 88db and I want to boost their output when paired with the rest of the system (Focal TDC90b and TBD midrange).

Also.. what potental crosover gotchas will arise when using this setup?

[johninCR]

Series wiring can be a bad thing due to issues of back EMF being sent to from one driver to another.

Parallel wiring is good as long as your amp can handle it. It will affect your crossover due to the halved impedance. One good thing is that the inductor values are smaller, so it's less wire and less resistance in your crossover.

However, it does present another problem of impedance and level matching. Your increased sensitivity and reduced impedance of your woofer section may overpower your HF output.

[Kittle]

whats "back EMF" ? ... in laymans terms.

level matching is why im looking to do this. with the woofer @ 88db, the tweeter at 91db and the midrange probably 90-93 the low end needs help.

[johninCR]

Hopefully one of the experts can correct me to the extent I am wrong, but I'll take a stab.

Not only does a driver turn an electrical signal into acoustical output, but it generates some electrical energy too, similar to the way a microphone (which is just a small speaker) creates electrical signals. With parallel wiring the signals are sent back to the amp which damps them. With series wiring, a signal is passed through a driver, which changes the signal to some extent. Then that changed signal is sent on to the next driver and so on.

I use a lot of cheap drivers for projects and the difference between parallel and series wiring is often very audible. I believe this is due to inherent distortion of the drivers. While the distortion of a single driver may not be audible within a certain range, if you string them together in series the signal is distorted by the first one, then the second one distorts it further, etc. This results in summing the percentage of distortion.

[Cal Weldon]

Originally posted by Kittle
level matching is why im looking to do this. with the woofer @ 88db, the tweeter at 91db and the midrange probably 90-93 the low end needs help.

You can always use resistors you know.

I have a 96dB woof with a 108dB tweet and have to load the tweeter with a 4ohm in series and an 8 ohm in parallel just so it doesn't scream at me.

Or you can use an EQ to boost the bass if these speakers are for your own use.

Cal

[Kittle]

johninCR - Thanks! That clears things up nicely.


Cal - yes I could use resistors, or eq stuff... Except I laready have 8 of the woofer drivers -- 2 each in 4 existing cabinets.

Im redoing my mains and id like to windup with more efficency, instead of less when all is done. And of course less components in the signal path.