speaker impeadance

[dr.colossus]

pardon my stupidity, but is there some way to change the impeadance of a speaker? i figure there must be, but i cant work out what... reason being if you wire two 8ohm speakers in a sieries the total impeadance becomes 4ohms, right? so there must be a way to through a "dummy" speaker in there... i don't know much about electronics, but my first guess was to use a resistor, but now i'm not so sure... please help

 

[LooneyTunez]

reason being if you wire two 8ohm speakers in a sieries the total impeadance becomes 4ohms, right?

Um, no. If you wire two 8 ohm speakers in parallel you get 4 ohms. If you wire two 8 ohm speakers in series you get 16 ohms.

I'll let someone else answer whether or not you could change impedance with a dummy load...

 

[dr.colossus]

with that in mind LT a quad-box with 4x16ohm speakers would then have an impeidance of 64ohms.... unless i used the word sieries where i should have used parralel...

 

[Phloodpants]

Not necessarily. You could wire four 16-ohm speakers in parallel for a 4 ohm load, or alternately you could wire two pairs in parallel, and wire the parallel pairs in series with each other for a 16ohm load.

As for changing the impedance of the load... if you have a 4 ohm load and you have an amp that won't handle it, you can raise the load to 8 ohms by putting a 4 ohm resistor in series with the speaker. (dummy speaker as you put it) Unfortunately, that means that half the delivered power from the amp will go into the resistor and half into the speaker. the resistor will have to dissipate this energy as heat, so you need a big resistor!

So you're pissing amplifier power away, and besides that, you destroy your damping factor, resulting in flabby bass.

Not recommended!

 

[dr.colossus]

i am slowly understanding... i left for work so confused after reading all that what i really want to do is reduce the impeadance of a 16ohm speaker to 8ohms, but its probably not a good idea right, but if i wanted to i could run a 16ohm resistor parallel...

is it nescesary to reduce the impeadance to match that of the amp output?

am i headed in the wrong direction all toghether?

should i just stick to playing the drums?

 

[MONTE]

It's probably not necassary to worry about it (except in special cases) if you are going to a higher impedance. There will be less current draw on the amp and you might possibly not get the full output of the amp. You stand more chance of having problems pissing around with resistors. If you parallel a 16 ohm resistor there are at least 2 problems. 1) It will have to be extremely high wattage and large to be able to dissipate the power delivered by the amp. 2) If your speaker is 16 ohms and the resistor is 16 ohms, half of your total power will go across each device. Keep in mind the resistor is not going to make any sound. This will cause you to run your amp at much higher levels to achieve the same sound as having one 8 ohm driver or even a 16.

NOTE: THIS IS MEANT TO BE A VERY GENERAL STATEMENT. Without knowing precisely what amp and speaker you are talking about

 

[Phloodpants]

Ditto what Monte said!

 

[dr.colossus]

speaker ; 16ohm 12" plessey

amp: 25watt 1950's A.W.A

so bassically (i am a drummer) if an amp is "rated" at 8ohms it is ok to use a speaker above 8ohms, but you do lose some power

 

[LooneyTunez]

if an amp is "rated" at 8ohms it is ok to use a speaker above 8ohms, but you do lose some power

Yes, it's perfectly fine to drive speakers that are of higher impedance than what the amp is rated at. Yes, you will lose some power (probably close to half).

 

[MONTE]

Keep in mind that while it is true that you will loose some power, the important thing is SPL. In other words how loud will it be? The cone of a speaker will only move so far, right? So if you can get it moving it's full travel and get good volume, who cares what the power output translates too. It's my view that too many people worry about the power thing. Ex: If you have a speaker rated at 100 watts but is not very efficient and another speaker that is rated at 35 watts that IS efficient many times you will be far better off. In other words, if you can produce 100db with 50 watts instead of 100db with 100 watts which system is more efficient?

 

[dr.colossus]

so power loss doesn't nescesarrily mean degredation in sound quality... they are some very good points monte, sounds like you know your shit... thanks LT and phloodpants, i'm a drummer so it may take a little longer to understand than most