Stereo Expert - Question before I purchase?

[SmokinBarrel]

I have a question?

I am going to use Polk MM651's (speaker), and so I will need an amp to power them correctly. I was informed that the ideal amp would be 100wx2 (RMS) - 150wx2 (RMS). The speakers are rated 100w (RMS) - 200w (Max), with a 2.7 ohm rating.

I am only going to have 2 speakers and no subwoofer - for know.

Can I use a 4-Channel amp at 4 ohms, so I only use 25 amps versus 50 amp draw at 2 ohms? It is my understanding the 4 ohms usually requires roughly 25 amps, and a 2 ohm setup will require roughly a 50 amp draw. The best amp I found at a reasonable cost is 60 - 90wx4 (RMS) at 4 ohms. I am thinking this will be sufficient enough, especially at the higher end RMS 90wx4.

Question:
1. Can I still use a 4-Channel amp for two speakers? It seems the wattage is lower on a 4-Channel for lower to mid amps.
2. Would 75wx2 (RMS) be sufficient? I was told that if you're not close to the speakers minimum (RMS) wattage, it has negative affects on the speaker (not as efficient - causing a fray at the edges)

As a note: I was told by Polk that the db651's where not completely sealed around the edge or in the middle - cannot remember. Anyway, the reason he recommended the MM651's because they're completely sealed. Otherwise, I would go with the db651's (rated at 4 ohms) because they have great reviews. But, the db651's are not sealed (100%), but will only be used around fresh water.

Music listening: Radio and Easy listening (75% of the time), Booty Music (for the ladies) (25%) of the time. Most likely 1 - 1.5 hours maximum continuous booty music.

 

[SmokinBarrel]

Re: Stereo Expert - Question before I purchase?

As in.... if the manufacturer rates its speaker at 2 or 2.7 ohms, then drive them at 2 ohms?

 

[Greg Mrozinski]

Re: Stereo Expert - Question before I purchase?

Smokin,

Let me try to answer in order:

Q: I am going to use Polk MM651's (speaker), and so I will need an amp to power them correctly. I was informed that the ideal amp would be 100wx2 (RMS) - 150wx2 (RMS).
A: Ideally yes so long as the amp is 2 ohm stable. If not then it will over heat. Most newer amps are 1 and 2 ohm stable however some cheaper amps are not.

Q: Can I use a 4-Channel amp at 4 ohms, so I only use 25 amps versus 50 amp draw at 2 ohms? It is my understanding the 4 ohms usually requires roughly 25 amps, and a 2 ohm setup will require roughly a 50 amp draw. The best amp I found at a reasonable cost is 60 - 90wx4 (RMS) at 4 ohms. I am thinking this will be sufficient enough, especially at the higher end RMS 90wx4.
A: There is a lot of confusing statements in here. You can use a four channel amp as long as it is bridgeable to give you two channel capability and is still 2ohm stable. If it is not 2ohm stable it will overheat.

Q: Can I still use a 4-Channel amp for two speakers? It seems the wattage is lower on a 4-Channel for lower to mid amps.
A: Yes see previous answer.

Q:Would 75wx2 (RMS) be sufficient? I was told that if you're not close to the speakers minimum (RMS) wattage, it has negative affects on the speaker (not as efficient - causing a fray at the edges)
A: Yes. If the speakers are rated at 100W RMS then you you can still power them with less wattage but they won't be as efficient meaning they won't get as loud and there will be some distortion at higher volume levels. You can control the distortion levels by properly adjusting the volume level on the head unit and the gain on the amp.

I think either speaker will probably work just fine. The sealing issue you are concerned about only relates to speaker efficiency/reponsiveness and not physical water leakage problems. If you decide to go with the Polk db651's then you may get better sound with an enclosure of some sort behind the speaker.