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What kind of amplifier do I need for these speakers? And how do I hook them up?

Well, I have an 8 ohm, 10 watt subwoofer, and I have a pair of 4 ohm, 5 watt speakers.

Does this mean I need an 8 ohm and 20 watt amplifier? Sorry if that is not the concept at all, as I don't have a very good grasp of audio.


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What you can do is use the lovely little LM386, 1 for the left and right channels, and 2 for the sub channel. The LM386 can be had in versions up to 1 watt. The datasheet is here. Go to page 5.

1.) For the left and right channels, use one of the amps. If you use the amp with a gain of 200, you can use a dual audio taper variable resistor to adjust the input level.

2.) For the subwoofer, use 2 amps: feed the same mono input to the amps, switching the inputs on the second one (feed the - or inverting input and ground the positive output, the opposite of the schematic) and then place the subwoofer between the outputs, no electrolytic caps needed. This will give 4 times the output power, so it will be up to 4 watts. Also, use the amp modification shown for bass boost.

3.) To make a mono feed from stereo feed, place 4 10Kohm resistors in a row (side by side). Split the right channel and feed it to resistor #1 and #3. Split the left channel and feed it to resistor #2 and #4. Now tie the other end of resistors #3 and #4 together. Now you have isolated left, right and mono.

This is why you want to use the gain of 200 version.

Qa
orksecurity6 years ago
Wattage of the speakers indicates the maximum power you can put into that speaker. A smaller amp is fine; if you use one with more power than that you need to be careful about how much of that power is reaching each of the speakers.

What you need is either an amp that has a separate mono subwoofer output, or a crossover (probably an active crossover if it has to mix stereo down to mono without creating crosstalk) that will separate the low frequencies the sub is designed for from the higher frequencies the others handle more efficiently.

There are some instructables related to this, such as https://www.instructables.com/id/Convert-a-passive-non-powered-subwoofer-to-power/

diggingeagle (author)  orksecurity6 years ago
But are there any 10 watt amplifiers out there for retail that have a mono subwoofer output, with all of things I need? Or would I need to buy a higher wattage amplifier and put a type of resistor in it?
. The amplifier can be rated for more watts than the speaker as long as you don't turn it up all the way. Anything from about 1W on up will work.
. The only part that is all that important is impedance matching. Make sure your amplifier is designed for 4 ohm speakers and an 8 ohm subwoofer.
diggingeagle (author)  NachoMahma6 years ago
But this:

http://www.ehow.com/how_7441081_use-speakers-8_ohm-powered-sub.html

suggests that 4 ohm speakers can be used with an 8 ohm powered subwoofer. Or, is this not preferrable?

also, would this work? It doesn't talk about ohms at all, but it is 10 watts.

http://www.smarthome.com/5135/Compact-10-Watt-Audio-Amplifier-ELK-800/p.aspx

same with this one:

http://www.hobbytron.com/10-watt.html
> this [link] suggests that 4 ohm speakers can be used with an 8 ohm powered subwoofer. Or, is this not preferrable?
.  It suggests replacing an 8 ohm driver with one or two 4 ohm drivers, not using it/them with a subwoofer. If you will re-read the article, it's not a very good idea.

> also, would this work? It doesn't talk about ohms at all, but it is 10 watts. [link]
.  Read the specs. "Output Speaker Load: 12 - 16 Ohms"

> same with this one: [link]
.  Specs are incomplete. You can just about bet that if speaker impedance is not mentioned, it will be 8 ohms or greater.