Confused about Wattage, Bi-amping, etc.

Assimilator87

Hi everyone,

I have a few questions so I thought I'd get them all answered in one thread. I know very little about speakers and a lot of researching, especially about bi-amping, has left me very confused and brainfried so bear with me.

To start off, does providing higher wattage to a speaker actually change the way it sounds or does it just play louder at the same level of quality? I'm using the amp built into the Z-5500 sub and the front channels are rated at 62W @ 1khz/10% THD. I'm sure that at full frequency range and less distortion, I'm getting extremely little usable power and the R50s are recommended to receive up to 150W. This leads into bi-amping.

So there's active and passive bi-amping, but let's focus on passive. Throughout all my Googling, I haven't been able to find any info about bi-amping into a non-BA compatible speaker e.g. just a single pair of binding posts. Can this be done? Wouldn't this configuration work just like having one higher powered amp instead of dealing with an amp dedicated to the woofers and another dedicated to the tweeters? If this is a doable setup, I'd like to try it out to see how much better or different my speakers will sound with more power.

Finally, I'll be picking up a used CS245i tomorrow for $65. Is this a good deal? I was deciding between that and a new CS1 or CS2 for $80 and $120 respectively. The CS245i has better specs than the CS2, but Polk's site shows the CS2 to be more expensive, which is a bit confusing.

I appreciate the help guys

strider

Yes, providing more wattage to a speaker can make them play louder. It's not a linear relationship, however, between watts and decibels. If I remember correctly, it takes 10 times the watts to double the loudness. the biggest benfit, in my opinion, of increased wattage is more available headroom. Say you're listening to a musical passage that's not very dynamic. The piece somes to a point in it when all of the sudden there's a loud crash of percussion, or a heavy bass line starts. This is where headroom comes into play. With little power available from the amp you'll still hear the percussion or bass line, but it won't be as defined as it could be. With more available power you'll have increased dynamic reproduction in your system. You'll still hear the underlying music in a defined fashion, but the sudden louder portion of the music will stand out far above.

From the link you provided, it looks like the Logitech system you have is an HTIB (home theater in a box) set up, right? Biamping may seem like the way to go because you're getting more watts into your speakers, but I think it's a bit too complex to do correctly for the situation you're in right now. My recommendation would be to get a quality stand alone audio video receiver (AVR) that has features that allow it to expand with your needs. Look for something with pre-outs; this allows the signal to come from the AVR unamplified so you can send it to an external amplifier when money and the upgrade bug find you at the same time. It doesn't need to cost a ton of money, but you can spend some serious coin if you really want to. Keep the Logitech speakers for the rear surrounds, you can upgrade later. I'd upgrade the sub after I got the AVR and new center.

I'm not real familiar with the centers you're referring to, but I'd get a used one in decent shape rather then a new one. I'd rather have a used speaker that cost more new, more speaker per dollar if you get my drift.

McLoki

While you may want to consider a better AVR, keep in mind the R50's are a very easy speaker to drive.

I would not consider bi-amping in your situation. In order to bi-amp, your crossover needs to have 2 separate paths to the drivers in your speakers. If you only have a single set of binding posts - you do NOT want to hook up two amplifiers to them. That is a quick path to purchasing new electronics and perhaps speakers. (i.e. - it will break things in a grand fashion)

You are almost always better off with a single larger amp than multiple smaller ones, but with the speakers you are running, they should sound really good with almost any commercially available AVR. Don't worry about bi-amping.

Michael

mhardy6647

strider wrote: »

Yes, providing more wattage to a speaker can make them play louder. It's not a linear relationship, however, between watts and decibels. If I remember correctly, it takes 10 times the watts to double the loudness.

You remember correctly. Doubling the power input will increase sound output by only 3 dB (an audible -- but not profound -- increase). The relationship between power and sound quality is complicated and murky at best; it's best explored empirically, IMNSHO.

I am not particuarly a fan of brute (continuous) power per se. My everyday amplifier is capable of about 12 watts per channel at reasonable levels of distortion; works great with speakers of ca. 100 dB per watt at 1 meter sensitivity.

Assimilator87

McLoki wrote: »

I would not consider bi-amping in your situation. In order to bi-amp, your crossover needs to have 2 separate paths to the drivers in your speakers. If you only have a single set of binding posts - you do NOT want to hook up two amplifiers to them. That is a quick path to purchasing new electronics and perhaps speakers. (i.e. - it will break things in a grand fashion)

Would you give me an explanation of why this setup is not recommended? I don't understand how this is different from running one higher wattage amp to the speakers.

McLoki

On the outputs of an amplifier - power is supposed to flow out, not in. With both amps tied together on a single binding post - the power will travel in the direction of least resistance. (that would typically be to the other amp, not the speaker) - basically it will overload your amp and if you are lucky - blow fuses and trip circuits. if you are not lucky - flames and smoke will quickly follow.

cnh

I haven't heard your center. But one of the reasons it's cheaper is because it's an older model...I think much older than the CS series. The CS2 of course is better than the CS1. Specs don't mean that much per se.

That CS245i looks like it has the old style tri-lam tweeter. And it is probably more compatible with the Rti line? But I could be wrong here. As I am not very familiar with that center.

Now that you have it, what do 'you' think of it?

cnh