Thread: Speaker control box thingy

I am not sure, but have you tried

www.altronics.com.au
www.jaycar.com.au
http://www.wescomponents.com/
http://au.farnell.com/jsp/home/homepage.jsp
http://www.madisontech.com/index.php
www.audiotelex.com.au

Sorry, I couldn't be more specific

WoodyKnot,

Check the ratings of your amp to verify whether it will safely handle a 4 ohm load. Many amps will and some will have a speaker selector switch built in.

Are you trying to turn speakers in primary or remote locations on and off, or are you trying to add local volume controls (attenuators) in each location. Both systems are available and both have drawbacks.

Most of the switch boxes around allow you to switch main and aux speaker sets in and out literally only switch the speakers and do not do anything to attempt to adjust the load impedance seen by the amp. This is a viable and simple approach provided that the expectations for volume and the speakers allocated to each area are similar. It does not work nicely if you want loud in one room and quiet in another, or you have highly efficient speakers in one area and low efficiency speakers in another due to the sound levels generated being a compromise between the rooms.

On the other hand, using attenuators in line with the speakers gives you the ability to adjust volumes in either area fairly independantly of each other, and without differences in speaker efficiency affecting the system unduly. However, as a penalty, the attenuators are normally being fed power whenever the amp is producing an output signal, and are wasting (converting to heat) any signal not being passed to the speakers. They also represent an increase in the source resistance seen by the speaker which adversely affects speaker damping and can vary crossover points etc.

unfortunately the vast majority of "modern " amps will not drive 4 ohms, which is a rean come down and a PITA.

Unfortunately there is no "good way" arround the problem if your amp wont drive 4 ohms.

most of the cheap speaker switchers either series paralell the speakers or insert resistors.... both situations are realy bad for damping factor.
Most of said similar switchers also have crummy switches and spring terminals.......I have yet to see a good one.

The slightly better way to do it is to get a transformer based speaker splitter but to get a decent one will be costly AND quite a number of amps will not tolerate the reactive load the transformer introduces... I've seen a certain well known brand amp smoke its output stage simply by being connected to a transformer.

as for volume controlls..... there ae resistive "L"pad bassed controlls still arround but they do have the problems mentioned above AND they generaly only handle 100watts AND if driven hard and high attenuation are prone to burn out.........then there are the transformer bassed volume controlls..... they are much nicer but are usualy low powered and have the transformer issues mentioned.

the best option would be to run a slave amp for the second set of speakers.
Check out jaycar.. they have some cheap and cheerfull amps that are quite respectable.

cheers

Originally Posted by WoodyKnot

Hey folks, anyone know where i can get a control box or a kit to build for 2 sets of speakers so that the amp thinks it still has 8ohms to it when 4 speakers are connected?
I see dick smith sells 'em but they're only rated to 100watts and I want one rated to at least 150W or more.
Thanks,
Woodyknot

If the speakers are identical, place them in series. If not, buy another amp. Run one amp, per pair of speakers.