Help choosing amp for non standard speakers

[xandt]

Hi,

I have two large "bookshelf" speakers and each speaker has its own sub. So I have four pairs of wires to hook up (a standard red/black pair for each main speaker/tweeter and another red/black pair for each sub).

Each main speaker: 100 watts, 4 ohms
Each sub: 180 watts, 6 ohms
(Total = 560 watts RMS)

I'm having a lot of trouble finding an appropriate amp or receiver for these speakers. Preferably I'd like to get a simple amp since I don't need all the extra features that usually come with a receiver. I'm doing this little project for fun so I don't want to invest too much money ($50-$200). The speakers were free.

I can only find receivers with dual-sub outputs and they are way too expensive. So I'm guessing I'll need two separate amps instead, or I'll use a 2.1 channel amp and just not hook up the second sub. From what I can tell I'll also be stuck with a much weaker amp than I need (< 560W RMS), but that's fine too. This is for fun after all, I want the speakers to work "well" and not necessarily at full power.

So... I was hoping some knowledgeable person here could point me at an appropriate amp/receiver. I'm not sure how weak of an amp I'm allowed getting. I don't want to fry it by accident...

Please and thank you for any advice

 

[highfigh]

Hi,

I have two large "bookshelf" speakers and each speaker has its own sub. So I have four pairs of wires to hook up (a standard red/black pair for each main speaker/tweeter and another red/black pair for each sub).

Each main speaker: 100 watts, 4 ohms
Each sub: 180 watts, 6 ohms
(Total = 560 watts RMS)

I'm having a lot of trouble finding an appropriate amp or receiver for these speakers. Preferably I'd like to get a simple amp since I don't need all the extra features that usually come with a receiver. I'm doing this little project for fun so I don't want to invest too much money ($50-$200). The speakers were free.

I can only find receivers with dual-sub outputs and they are way too expensive. So I'm guessing I'll need two separate amps instead, or I'll use a 2.1 channel amp and just not hook up the second sub. From what I can tell I'll also be stuck with a much weaker amp than I need (< 560W RMS), but that's fine too. This is for fun after all, I want the speakers to work "well" and not necessarily at full power.

So... I was hoping some knowledgeable person here could point me at an appropriate amp/receiver. I'm not sure how weak of an amp I'm allowed getting. I don't want to fry it by accident...

Please and thank you for any advice

Power handling is one thing and "how much do I need?" is usually another. If you never listen at high volume levels, you don't need as much as the speakers will handle.

What make and model are the speakers? If you post more than the minimum of 5 (if I remember), you'll be able to put some photos up so we can see what you have and that will make it easier to recommend something.

 

[xandt]

Sorry but I won't have the speakers until next week. A buddy of mine is dropping them off. I wrote down a few specs about them so I could start looking for an amp. I think they were part of an all-in-one stereo system that got destroyed, so they're not meant to be used with anything other than that system. I can't remember what brand they were but it was a popular one, like Sony, Panasonic, or something similar. It was a top of the line model, but not for professional use.

As far as how much power I need... well, the louder they go the more places I can use them So I'd want them pushed to their full potential if possible. But I am on a budget so I'm not expecting too much. I'm more interested in quality of sound than raw power, if that helps.

 

[CraigV]

Does each sub have it’s own amplifier? If not, you could use 4 channels of a 5 channel amp.

 

[xandt]

The subs don't have their own amps.

I'd be willing to try a 5 channel amp if it would work, but the few 5.1 receivers I looked at didn't seem compatible... Some even had giant warning labels that said not to plug anything crazy into the rear channels. That's just what I saw anyway.

 

[CraigV]

Not a 5 channel receiver, you want a 5 channel amplifier. With a receiver, you would be mixing front & rear channels. If you have a pre-amp (or a receiver with pre-outs) you could make a “Y” connection so your left channel is feeding into two of the channels, and your right channel is feeding into two of your channels. Then you run speaker wire from the two amplifier channels hooked up as “left” – one wire to the mid/high drivers, and the other to the sub. Then repeat for the right channel. In a sense, you’re bi-amping the speakers.

http://emotiva.com/xpa5.shtm

…as an example

 

[polsol]

Xandt,

Assuming that your subs have a variable frequency and volume (gain) settings you can simply use a stereo amplifier and feed from your amp to each sub and then from the sub to the speakers -i.e. wire them in parallel.
Then all you have to do is adjust the subs frequency and gain to match the speakers. Pretty simple really amp=subs=speakers.
if the subs don't have variable gain and frequency controls then you need to use a 5.1 receiever and connect each speaker/sub seperately to one channel (i.e. 4 channels of the 5.1) then play around with the frequency/gain of the channels to match - if the receiver allows for this, which I doubt
In reality, one has to match the 'cross over' of the subs to the speakers. In other words if the subs have a frequency response of say 100 to 30 Hz and if the speakers go from 20 Khz down to say 50 Hz both speaker and sub will both have a 'combined' output from 100 to 50Hz - effectively doubling the output power between 100 and 50 Hz. Thus you'll get an output 'hump' in this region rather than a smooth (linear) frequency response across the range 20 Khz to 30 Hz. So it's a matter of adjusting the subs output to compensate for the speaker.
Maybe my Greek is better
Graphically it's very obvious though.

 

[alexwakelin]

It's hard to say what equipment you will need without actually seeing the speakers, but if you shop around and look for good deals you could get for $200-$250:

2 Audiosource Amp 100's
Behringer cx 2310 crossover

 

[xandt]

I don't want to tie up any of my other equipment with these speakers. The idea is to start with only these speakers and add just enough components to make them work.

CraigV: As I understand it you're saying to use a regular stereo output and split each of the 2 channels between one sub and one main speaker. Wouldn't that create too large of a load per channel? I forget how adding ohms works but 6 and 4 on the same channel would make it the equivalent of one speaker with 2 or 3 ohms? I might be totally wrong though... Either way, could you recommend a cheap amp for this type of setup?

polsol: There are no settings on the sub, just two speaker wires coming out of a box. I do understand what you're saying about the 'humps' (even though I don't remember how the number crunching works, but that's not important right now). So are you saying that I'll need adjustment knobs on my amp no matter what, or can this be avoided?

I did get a little more info on the speakers. Each sub: 6 ohms, at 63Hz. Each main speaker: 4 ohms, at 1kHz.

alexwakelin: That setup is just a bit outside my price range. What more do you (or anyone else) need to know about these speakers?

Keep in mind I want to maximize performance per dollar spent. ie. I'd rather spend $100 and make a 6/10 system than spend $200 and make a 7.5/10 system. Doubling the price is not worth the extra 15% increase. At least not for this project.

Thanks again for all your input.

 

[xandt]

Ok I'm not going to push this if no one is interested, but I'll add one more thing.

I've decided to put whatever becomes of this system into my garage. For FM radio and MP3 listening (not FLAC or anything high quality). Quality of amp is not important to me (as long as its not utter crap).

I spent some time browsing the web and I think what I need is either a 2 channel integrated amp or a cheap receiver, like a Harman Kardon HK 3380 maybe? Can anyone recommend any decent cheap integrated amps? If I do choose a 2 channel amp I might try using just one speaker for now (I'd see how that goes and expand the system if I thought it was worth doing).

 

[Lordoftherings]

Ok I'm not going to push this if no one is interested, but I'll add one more thing.

I've decided to put whatever becomes of this system into my garage. For FM radio and MP3 listening (not FLAC or anything high quality). Quality of amp is not important to me (as long as its not utter crap).

I spent some time browsing the web and I think what I need is either a 2 channel integrated amp or a cheap receiver, like a Harman Kardon HK 3380 maybe? Can anyone recommend any decent cheap integrated amps? If I do choose a 2 channel amp I might try using just one speaker for now (I'd see how that goes and expand the system if I thought it was worth doing).

Hi,

I was going to ask you to wait till you can give us more information as the brand of your speakers, but no need now, I figure it out.

Just get a used Stereo receiver from the internet for about $100 or so.
Look at Yamaha, Denon, Marantz, Onkyo and Pioneer. You might even find one for $50.
And just forget about Harman Kardon, Sony, JVC and other brands like that.

Look for one with about 60 to 100 watts per channel, that is rated for 4ohm loads and that have two set of speakers (A & B). Some Denon and Yamaha models fall under that category. If you're into AM/FM radio, look for a stereo receiver; if not, look for a stereo integrated amp.

Hope that helps,

Bob

 

[CraigV]

CraigV: As I understand it you're saying to use a regular stereo output and split each of the 2 channels between one sub and one main speaker. Wouldn't that create too large of a load per channel? I forget how adding ohms works but 6 and 4 on the same channel would make it the equivalent of one speaker with 2 or 3 ohms? I might be totally wrong though... Either way, could you recommend a cheap amp for this type of setup?

No, each channel of the amp would be driving a different load, they would not be added together.