Confused about amp/rec/spk setup

[computerdude]

I don't really know much about amps, so I'll try to explain my questions as best as I can. I have a very stereo receiver that supports 4 speakers. On the back of the receiver, it says "190w max". On the front, there's a power meter that has two sides, left and right, and goes from 1 to 50. I assumed this meant the receiver supported up to 100w, total? The two speakers I have connected are 40w each. I just purchased another older set of speakers that are 70w each..(haven't received them yet.) I'm assuming I would need an amp to be able to run all 4 speakers? If so I would like to be able to still use my receiver for my components, which include a CD player, dual tape deck, and turntable. Also, if I do need an amp, would I be able to use the amp for one set of speakers and the receiver for another?

Any help would be greatly appreciated!!

Thanks!

I don't know if it helps at all, but my receiver is a Technics SA-2029.
If pictures would be of any help, I'd be glad to post.

 

[Jack N]

“On the back of the receiver, it says "190w max".” More than likely, this is referring to maximum amount of current draw that the receiver will pull from the electrical socket in the wall. This would sound about right considering the output capabilities of the amp.

“On the front, there's a power meter that has two sides, left and right, and goes from 1 to 50. I assumed this meant the receiver supported up to 100w, total?” I’m not sure what you mean by “supported”, but the meters are showing you how much power the amplifier is sending to each channel to drive the speakers.

“The two speakers I have connected are 40w each.” This is a power capacity rating. It doesn’t mean they draw 40 watts.

“I'm assuming I would need an amp to be able to run all 4 speakers?” No. Your current receiver will work just fine. What you will notice however is that one pair of speakers will play louder than the other pair because they’re not identical speakers. There’s also a good chance that you’ll notice a Timber mismatch – meaning that the two pairs will sound differently.

CAUTION: It’s very important that you find out the impedance rating (ohms) for each speaker before hooking up the extra pair. If each speaker doesn’t have at least 8 ohms of resistance, you will dramatically shorten the life of your receiver because the amplifier in that particular model isn’t built to handle low-ohm loads. It's ok to drive one pair of speakers with less than 8 ohms. If you're driving 2 pair, each speaker must have at least 8 ohms of resistance.

 

[computerdude]

Thanks!

Thanks for all your help; I really apppreciate it. I know the set of speakers I'm getting has an 8 ohms impedance. I think the ones I have currently are 8 as well; I see an 8 next to what looks like an upside down U, after "impedance", but its sorta faded. My only other question was is there anyway to balance the volume level between both sets of speakers?
Thanks!!

 

[jaxvon]

Pictures would be grand. If you can, post them on photobucket, or another hosting site, and link them here so we can see large resolution pics.

 

[Jack N]

“My only other question was is there anyway to balance the volume level between both sets of speakers?” Listen to them first. You might get lucky and they may sound fine just the way they are and you won't need to balance them. It all depends on what you’re willing to accept for an imbalance. Speakers from different model lines and manufacturers play any one given frequency at different loudness levels. So it will be impossible to get a perfect balance, but you should be able to get one within reason. All it entails is inserting resistors in the speaker wires going to the loudest speakers. For your system, I would recommend coil wound resistors with a wattage rating of 15 to 25. This is going to be a trial and error thing as to how much resistance to add. If there’s just a little difference in loudness, you’ll want resistors of ½ or 1 ohm. If there’s a bigger difference, you may want to start out with 2 ohms. You may be able to find coil wound resistors that are adjustable – they have a moveable “tap” that allows you change the resistor’s impedance level. This would certainly be the easiest way, and would make it easier to fine tune the amount of resistance. If your system is equipped with a pink noise generator, it’ll make the trial and error thing a little easier – it also makes it possible to use an SPL meter that can be had at your local Radio Shack, to get the balancing closer than your ear can. Otherwise, just go with what sounds best to you. That’s all that matters. And be very careful not to short anything out. It's easy to do with resistors of this type.

 

[jcPanny]

Adjusting speaker levels

To calibrate the level of your two sets of speakers, consider purchasing an inexpensive volume control and pick up a single gang box from the hardware store. Use the VC to attenuate the volume on the louder set of speakers or to turn them off. You also might be able to find an inexpensive speaker switch box with a volume level function.