Help! Need 2 ohm amp

[jayfremont]

Like a dolt, I decided to wired my living room for six ceiling speakers without asking for advice. I daisy chained three speakers on a single strand of 12 guage wire on the left channel and daisy chained three more on a single strand on the right channel. (Hey, if it works for light fixtures, why not speakers.) I've since learned that this drops the resistence of my speakers from 8 ohms to 2 ohms.

Which two channel power amp would you recommend for running at 2 ohms? The local audio store recommends a Niles SI-275 with Niles SSVC-2 selector box.

I don't need a 2 ohm receiver, just an amp. I plan to use the amp to ampliphy a signal produced by a main AV receiver in another room (I'm considering a Rotel 1068 or Sunfire Ulitimate II). I'm willing to spend up to about $1000 for the 2 ohm amp.

 

[porziob]

need for 2 ohm amp

Explain exactly what you mean by daisy chained. To me, this would indicate they`re wired in series thus presenting no problem to the amp. Are you positive they`re wired in parallell? That`s the only way you could have a 2 ohm problem.

 

[jayfremont]

I'm a neophyte. Let explain what I have in the walls and perhaps you can tell what it's called and how to make the best of it.

For the "right" channel, I have a 40' length of two-stranded 12 guage speaker wire (the wire is similar to regular extension cord wire) running through the wall from the amp location to the first "right" ceiling speaker location, then a 15' length of the same wire to the second "right" ceiling speaker location, another 15' length of the same running to the third "right" ceiling speaker location, and finally a 20' length of the same running down through the far wall to a spot where I hope to connect a self amplified subwoofer. I have the installed the same set of wires for the three "left" ceiling speakers and subwoofer. Currently, I have wired the speakers in what I believe is called "parallel". I don't know much about wiring speakers, but I believe I could re-wire the speakers in "series" using the same wires by creating a loop with a bunch of wire nuts. Would that make more sense?

 

[JKnPA]

Loudspeaker sticky.............

Jay,
Daisy chained......... normally means in parallel. If you connected them + to+ (red) and - to -(black) they are in parallel.
This is a link to the 'sticky' under 'Loudspeakers' that explains the topic....................... a must read for 'DIY' scientists........

http://www.audioholics.com/techtips/audioprinciples/loudspeakers/LoudspeakerImpedance.php
JK

 

[j_garcia]

Connect the first two parallel and the third in series. You should be fine with a typical amp that is 4 Ohm stable, which most decent 2ch amps are.

 

[jayfremont]

Thank you for offering your advice and sending the article. My six B&W CCM80 in-ceiling speakers are currently connected in parallel--three per channel. Would you recommend:

1. Buying a 2 ohm amp?
2. Buying a regular amp and wiring two speakers in parallel and the third in series?
3. Buying a regular amp and a Niles speaker selector?

I have to buy a new amp either way.

 

[xboxweasel]

Anthem makes a MCA20. 2 channel amp. 410W/channel @ 2ohm. Around $1000.

 

[billnchristy]

I reccommend buying a cheap multimeter so you can see what the resistance actually is.

Decide from there.

3 8ohms should be closer to 3 ohm and you could very well be less than 2.

 

[Haoleb]

I reccommend buying a cheap multimeter so you can see what the resistance actually is.

Decide from there.

3 8ohms should be closer to 3 ohm and you could very well be less than 2.

Speakers are measured by impedance, They have a different amount of resistance depending on the frequency. The nominal impedance is what speakers are rated at which is an average. You cannot accurately measure speaker resistance by the method above.

I suggest that you look for an amp that has high current capability rather than something with a high wattage rating.

 

[xboxweasel]

I suggest that you look for an amp that has high current capability rather than something with a high wattage rating.

Doesn't high current and high wattage go hand in hand?

 

[Haoleb]

Not all amplfiiers out are capable of true high current delivery. Some are made for voltage gain, some for current. Some just claim alot of wattage but in the real world dont deliver.

 

[Nomo]

Like a dolt, I decided to wired my living room for six ceiling speakers without asking for advice. I daisy chained three speakers on a single strand of 12 guage wire on the left channel and daisy chained three more on a single strand on the right channel. (Hey, if it works for light fixtures, why not speakers.) I've since learned that this drops the resistence of my speakers from 8 ohms to 2 ohms.

Which two channel power amp would you recommend for running at 2 ohms? The local audio store recommends a Niles SI-275 with Niles SSVC-2 selector box.

I don't need a 2 ohm receiver, just an amp. I plan to use the amp to ampliphy a signal produced by a main AV receiver in another room (I'm considering a Rotel 1068 or Sunfire Ulitimate II). I'm willing to spend up to about $1000 for the 2 ohm amp.

Just assuming that those speakers are 8 ohm, and they probably are, 8 ohms is just an average impedance measurement dependant on certain frequencies.
At other frequencies the speakers my show an actual impedance of 6 ohms. that lessens your configuation to 1.5 ohms. Most likely more than the sturdiest of amps is willing to handle at higher volumes.

IMHO, running that speaker configuration is just a really bad idea.

 

[xboxweasel]

Not all amplfiiers out are capable of true high current delivery. Some are made for voltage gain, some for current. Some just claim alot of wattage but in the real world dont deliver.

And how would one tell which type a given amp is?

 

[Nuglets]

And how would one tell which type a given amp is?

Not sure if this is 100% but my amps are labeled as 'high current'.

 

[Jack N]

“IMHO, running that speaker configuration is just a really bad idea.”

Agreed. Just to help clarify loads that an amp could see, I’ve read reports where good quality speakers rated at 8 ohms will drop as low as 3.6 ohms at certain frequencies. In your configuration, this works out to 1.2 ohms. This type of load will put a tremendous strain, albeit momentary, on the amp. Also, there’s a chance that you’d lose a good portion of your dynamic range simply because the power supply will have trouble keeping up at higher volumes. High loads also increase distortion levels, and distortion is what does the most damage to speakers. In my own opinion, I’d have to think that an average steady diet of 2.67 ohms is just too taxing on an amp, even for those rated down to 2 ohms. It has got to shorten its’ life. I too would recommend using a different wiring configuration. It’s safer, better sounding, will add longevity to your equipment, and will open up your choices in amp selection (less $).

 

[GreenJelly]

“IMHO, running that speaker configuration is just a really bad idea.”

Agreed. Just to help clarify loads that an amp could see, I’ve read reports where good quality speakers rated at 8 ohms will drop as low as 3.6 ohms at certain frequencies. In your configuration, this works out to 1.2 ohms. This type of load will put a tremendous strain, albeit momentary, on the amp. Also, there’s a chance that you’d lose a good portion of your dynamic range simply because the power supply will have trouble keeping up at higher volumes. High loads also increase distortion levels, and distortion is what does the most damage to speakers. In my own opinion, I’d have to think that an average steady diet of 2.67 ohms is just too taxing on an amp, even for those rated down to 2 ohms. It has got to shorten its’ life. I too would recommend using a different wiring configuration. It’s safer, better sounding, will add longevity to your equipment, and will open up your choices in amp selection (less $).

...Buy the extended warrenty plan...

 

[jayfremont]

It sounds like a 2 ohm amp by itself won't fix my problem. Should I

1. Wire two speakers in parallel and the third in series to increase impedence as suggested by j_garcia and indirectly by JKnPA? or

2. Buy a Niles speaker selector to normalize impedence as suggested by two local hi-fi shops?

Which would produce better sound (or more accurately, which will hurt audio quality less)?

You have all been enormously helpful and are a credit to the Audioholics community. I only wish I had known about this forum before I covered my ceiling with wood panelling.

I was such a dolt....

 

[markw]

Forget that speaker selector. It's too late for that now.

Had each of the three speakers been individually wired, and those three wire pairs were run from one location (by the switchbox) to the individual speakers, then it would have been the ideal solution.

So, unless you plan on runninng new wires to each individual speaker, fuggedaboudit.

 

[GreenJelly]

I dont understand why you would want such a setup... More speakers can only mean more sound (louder). As you stress an amp you will get more clipping and distortion, leading to speaker damage. Thats if you dont overheat the amp.

I would recommend buying a couple amps, and then run them that way... Most likely three speakers on one amp will cause the amp to have a short lifespan. There are amps that can handle this load, but they are not inexpensive.

I am tempted to buy a pair of good thiel speakers and use them both for a center channel, but I would buy a seperate amp for this. I would personally get better sound out of a more expensive center channel then the cost of two speakers plus an amp.

I would have suggested you to a spend money on a single pair of really good speakers, rather then spending the thousands of dollars required to power these three.

The only reason I can see you having so many speakers on two channels is if you were using them for commercial reasons (aka concerts etc.)! The additional speakers will not provide a good home audio system, nor will it be good for 5.1!

Another suggestion is to simply use the speakers you got and use them in a 5.1 channel setup, or to buy a 3-4 channel amp and power each speaker individually. Luckily there are allot of 8 ohm amps that are around $1k.

With a 3x2 channel amp you can then control the volume and the ranges of each speaker with additional equipment (passive crossover) or a Mixer. Passive crossovers are rather easy to construct, and will provide great sound at a low price.

 

[WmAx]

Like a dolt, I decided to wired my living room for six ceiling speakers without asking for advice. I daisy chained three speakers on a single strand of 12 guage wire on the left channel and daisy chained three more on a single strand on the right channel. (Hey, if it works for light fixtures, why not speakers.) I've since learned that this drops the resistence of my speakers from 8 ohms to 2 ohms.

Which two channel power amp would you recommend for running at 2 ohms? The local audio store recommends a Niles SI-275 with Niles SSVC-2 selector box.

I don't need a 2 ohm receiver, just an amp. I plan to use the amp to ampliphy a signal produced by a main AV receiver in another room (I'm considering a Rotel 1068 or Sunfire Ulitimate II). I'm willing to spend up to about $1000 for the 2 ohm amp.

No need to spend that much. A Behringer EP2500, for $330, will easily provide the power you need into a 2 ohm load, and in fact, will provide much more power than you will ever want to use, since it can output over 1000 watts per channel into 2 ohm loads, assuming you have a dedicated 20 amp circuit just for the amp.

http://www.zzounds.com/item--BEHEP2500

-Chris