Do I need a better amp?

kkennally

I have a pair of Polk Lsi 9's powered by a Cambridge Audio 740a Amp. It almost seems like the Amp is underpowered for these speakers. Should I go with a bigger amp?

Setup:
Polk Audio LSI 9's
Cambridge Audio 740a 100x2 Integrated Amp.
Cambridge Audio 640c V2 CD Player
Velodyne SPL 800 Subwoofer
Audioquest diamond back interconnect.

See picture.

thuffman03

I don't think that is a bad choice for those speakers. 150wpc into 4 ohms. Though I always say you can never have too much power. I wonder what a 250+ wpc amp would sound like.

BTW your listening room is pretty cool. I like it a lot.

AudioGenics

nice system
LSi9 are 4 ohm so your Azur will be rated at 150 wpc.

perhaps you have outgrown the current sound and want something better or different.

options are wide open to you

kkennally

I guess I was just expecting more volume from the amp. The speakers that I replaced Polk RT1000i's seemed a bit louder than the Lsi 9's at the same volume level.
Maybe I just have some hearing loss......

AudioGenics

ahhh... your last statement regarding volume make me think that you need to
read about SPL DB Volume and logarithm scales

lots of stuff when you google
for example

http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm

AudioGenics

just copied and just one opinion (not necessarily mine)

Notice: Psychoacousticians say that a level increase of 10 dB
give the impression of a loudness (volume) doubling.
Your loudspeakers need 10 times more power.
If you have 6 violins as source, then you have to tenfold the violins;
so you need 60 violins to double the psycho-acoustic volume.

cnh

Just out of curiosity....how LONG have you had this set up and are the LSIs past the break-in period? They probably are but it never hurts to ask...because it takes time for things to OPEN up.

cnh

markmarc

One thing to remember, the LSi9's aren't designed to blast the night away. Instead of worrying about power, I'd look into upgrading the x-overs. The LSi9's deserved to be heard reaching their potential, instead saddled in mediocrity. Do a forum search for x-over upgrades.

madmax

The LSi9's can use way more power than than what you are feeding them. Mine sang nicely with around 10 times that much. They get bigger and fuller as you add tons of power. Clean power is key. Keep in mind you are more likely to damage the drivers with lower power turned up to clipping than you are feeding them with 10 times their rated power handling from a big powerful clean amp. More is better.
madmax

cfrizz

Thank you Max! Finally someone gave out the right answer.

Kkennally, your RT1000i's were louder because they are easier to drive being 8ohm speakers, But you need a whole lot more power to get the same volume out of the LSI's. Think 200wpc @ 8ohms minimum & if you can afford more get more.

Welcome to CP!:)

madmax wrote: »

The LSi9's can use way more power than than what you are feeding them. Mine sang nicely with around 10 times that much. They get bigger and fuller as you add tons of power. Clean power is key. Keep in mind you are more likely to damage the drivers with lower power turned up to clipping than you are feeding them with 10 times their rated power handling from a big powerful clean amp. More is better.
madmax

madmax

cfrizz wrote: »

Think 200wpc @ 8ohms minimum & if you can afford more get more.

I knew this was coming.
madmax

Airplay355

Sell the whole thing and get one of these http://support.jvc.com/consumer/product.jsp?modelId=MODL027204&pathId=13&page=1&archive=true. 550 watts is way better then crappy Lsi's with 150 watts.

In all honesty I noticed you have a rather tiny sub sitting in the corner. When I had Lsi's with a musical fidelity integrated amp I would crank them and wish for more but when I turned it down my ears would be ringing. I think my problem was the Lsi's sounded so clear it was hard to judge just how loud it was, especially with the lack of low end bass (the stuff you'd only feel). My point is, maybe you're wishing it went louder because you're missing out on the low end bass and aren't feeling the music as much as you'd like.

Another option would be to get another similarly powered amp and use it for biamping. Like some other members pointed out, you'll need a hefty wattage increase before you start noticing big differences in loudness. That means spending more money. Getting another smaller amp would be cheaper. Instead of having your 150 watt amp power the whole speaker you could power just the tweeters with it.

Gaara

kkennally wrote: »

I guess I was just expecting more volume from the amp. The speakers that I replaced Polk RT1000i's seemed a bit louder than the Lsi 9's at the same volume level.
Maybe I just have some hearing loss......

Or it could be a difference in sensitivity. If the RT1000s were more efficient then your 9s then at the same "volume level" they would sound louder.

cfrizz

Of course it was! And it's a true statement. The LSI's simply need lots o power to operate to their full potential. Once he gets some he will be a very happy camper!:D

madmax wrote: »

I knew this was coming.
madmax

Hawkeye

Airplay355 nailed it. Your missing out on the bottom and turning up the volume in a vain attempt to "feel" it.

Before you buy another amp, upgrade your sub to something that can keep up with your speakers. A pair would be very nice!

Gordon

P.S. Some room treatment, i.e. bass traps and absorbers are highly recommended.

Hilbert

Just a thought---before you buy another sub, turn up the volume on the sub you have.

I have an SPL 800 also. It won't rattle the windows but it will make itself heard---especially if you choose the MOVIE auto-calibration setting on the remote.

If all else fails---maybe a big 5 channel amp and another pair of LSi9s?:)

mmadden28

If the sub is your issue - play with the crossover settings on the sub as well, if you're not crossing over correctly you could be canceling out the lows where the frequencies overlap between the sub and the LSi's.

leroyjr1

Sell the LSi 9's and get some SDA's.

bbq

awesome room buddy