AMP question

tnathan

I have pair of LSI 15's, FX's and some small speakers left over from my RM7500 which are run by a parasound 1206 (200wpc/4ohm). I would like to get some more punch out of the system. I have a few questions.

1) Is is advisable to run the same watts to each speaker including the surrounds? When I tested these speakers under normal operating conditions the surrounds did not seem to be drawing anything near 200 wpc. Would I be better of Bi-amping the front l,r and center and leave the rears at 75 wpc from my HK receiver?

2) Is there any problem with running 400 watts (200 bi-amped)into the lsi15's? Polk says they recommend a 100-250 watts. However, I have read a lot of comments where people say that it is ok to over amp by 2 as long as it is clean. I can't image a much cleaner signal than that from a thx certified parasound amp.

Thanks for your insight.

Tim

tnathan

I was looking at finishing my system. I was looking at a pair of lsi9's a few weeks ago. However, the deal fell through. Has anyone had any experience with this issue. LSI9's, LSI7's, or LSI FX's. I like the looks of the LSI'9's but am afraid they may be a waste of money concedering how much wattage the rears get. Should I save money and buy the LSI7's or would I be better off with the fx's?

Thanks.

Frank Z

I've got all 3!! Of course I don't have all of them in my HT though. I would suggest using the FX's in a 5.1 system instead of the 7's or 9's. The FX's will provide a better diffused surround sound, the direct firing speakers will cause the surround effects to be too localized. That being said, I do use 7's for the rear channels (#6 & 7).

FWIW, My amp cranks out 165w x 7 @ 4 ohms and thats plenty of power for me.

Ceruleance

if you listen to stereo only a lot then it might be a good idea to biamp the 15's. Wattage to each speaker doesnt matter as long as you have calibrated your system levels properly with an SPL meter. It's MY personal opinion that large rears are not worth the cost (I use 4 way powered tower mains, a 3 way center, and 2 way small bookshelves, fyi). Obviously stick with the LSi line because you will notice the timbre mismatch, especially if you ever get into multichannel music, but I would say go for the 7's or the F/X as the 9's potential will be wasted as a rear surround. You will have to make up your own mind as to whether you prefer bipole/dipole surrounds (F/X) or direct radiating (7s/9s) for surround use. I run a 7.1 system so I still get a full surround field with direct radiating speakers, but if I were to only run 5.1 I may have opted for bipole/dipole


EDIT: Frank got it as far as surrounds, the field will be more diffuse and believable with the F/X's (in a movie you don't want to say, oh, the sound is coming from the right back speaker now..)

per question 2) I run my 350 watt parasound amp into my polk speakers that are rated for 200 watts. Its no problem at all unless you actually put over the rated wattage into the speaker, that might melt some stuff. I doubt you will put that much wattage into the speaker unless you are really masochistic about your volume.

tnathan

Frank Z

Thanks for the reply. I think you said the same thing last time I asked. Perhaps it will sink in this time. Since the deal on the LSI9's fell through. I think I am going to focus on the fx's since they will give me a difuse surround.

I don't know why but I can't get enough sound. I want to see books hoping off the book shelf loud. I would like to try adding more power. I have been thinking about two options, but no one has had any ideas (or willing to encourage my insanity).

1) Bi-amp the fronts (l,r,c) to pump 400 wpc through the front and then rely upon the receiver to power the surrounds. HK says that the avr 430 pumps out 65 wpc into 8 ohms. Assuming that a 4 ohm load will not overload the reciever, I guess I would get 100wpc into the surrounds. I would hope that I could ballance the spl with my meter to get a good sound stage. I like this ideas because I utilize all my equipment without having to buy much extra. For that reason alone it may be worth trying.

2) ALternatively, I run the lsi15's with another (non bi-amped) amp with say 300-400 wpc and keep everything else on the parasound amp. I am not as keen on this idea since I need another amp and I still haven't heard from anyone why I need 200 wpc running into the surrounds. It seems to me almost everything (SAVD, DVD-Audio, Stereo, DTS) pumps most the information to the fronts.

For the sake of argument, if Polk made timber matched surrounds with 50wpc wouldn't they be able to handle the amount of voltage they are likely to see?

Anyway it is getting late thanks for the insight.

Tim

tnathan

Ceruleance,

Thanks for your help. I had a couple of follow-up questions.

FOr clarification, I have a 7.1 system. But I am trying to build as much backward flexibility as possible at a resonable price.

1) I am leaning towards the fx's for the rears. Based on what you and Frank said, going this direction would seem to provide a better movie surround. In your opinion will I be comprimising my stereo presence with CD's? Both you and Frank are using LSI 7 or 9's for the rear. Why did you go this direction?

2) I would like to try bi-amping the fronts but I have seen some controversy over whether you need to use an external crossover or not. I am not excited about second guessing polk's engineers.

Thanks again for your help

Frank Z

Everything that I was able to find on the World Wide Wait, magazines, professional audio sales types, all of these combined to help me decide that direct firing rear speakers were the bestoption. I haven't tried Bipole/Dipole speakers in place of my 7's, so I cannot say that my way is the best and everyone else is wrong. I can only tell you that to my ears, my set up works extremely well.

tnathan

No one has explained why but everyone seems to use forward firing speakers for the rear and fx's for the side. Those of you you replied to my request did this, polk recommends it. I don't know why but there is the answer to this question. Secondly, I tried bi-amping without an external crossover (per POLK's recommendation) I really didn't notice a big enough advantage to justiy using twice as many wires, amp channels, etc. There probably was an advanatage but not enough to justify the expense.

For anyone interested here is POLK's reply:



Hello,
In a 7.1 system we recommend using the LSi f/x on the side walls in line with the listener, then on the back wall facing forward use a front firing speaker. The LSi7 is an excellent choice in a complete LSi system.

Sincerely,
Lauren
Polk Audio

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Original Message

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From: timothy nathan [mailto:timothy_nathan@yahoo.com]
Sent: Wednesday, December 10, 2003 10:23 PM
To: Swauger, Ken
Subject: HOME: Customer Service



This message was sent from the polkaudio.com website
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I had a second question. I am looking to fill out my 7.1 lsi system. For the rears should I use fx\'s or lsi 7\'s. Lsi 9\'s seem to be a waste. Some of the people I discussed this with say that you want fx\'s the system is used for 7.1 output however this will difuse the signal if used for stereo. Alternatively, lsi 7\'s will produce too direct a sound which would be desirable for stereo signals but not for surround sound. What is the truth about this dispute? Since must of us use our systems is there a best setup? FX or 7\'s?

Thanks

jmierzur

Originally posted by tnathan
I don't know why but I can't get enough sound. I want to see books hoping off the book shelf loud. I would like to try adding more power. I have been thinking about two options, but no one has had any ideas (or willing to encourage my insanity).

To nudge the books off the shelf, try giving them a push with a good sub. Let your existing system do what it does best: produce great sound from the mid bass and up...

I do not think the LSi15's were designed to produce vast amounts of low bass, no matter how much power you try to feed them.