LSI 25 and amp shut down

pvabeach

I'm having trouble driving my LSI 25's to high volumes.
Setup-- Rotel RMB 1095 amp. 200w/ch into 8 ohms, 330 into 4 ohms specs. Line level inputs into lsi subs, top binding posts dissconnected from botton posts.
Rotell 1066 preamp. I'm just listening to 2 channel cd's, i.e. JUST driving lsi25's (sub off etc). When I get to about 95db avg reading on my snd level meter, after about 10-15 minutes, the amp protection circuits kick in. (volume setting '72-75' on rotel 1066...max setting is '90').
Amp very hot. (I am going to have dealer check amp), but as everything works fine at lower levels .......It seems hard to believe that this 80 lb amp can't drive these speakers!!!!!!!!!!!!!!!!!! I even have a dedicated 20amp circuit for system.
My question is, although lsi 25's are rated at 4 ohms, in use, do they drop to significantly lower ohms???? Using polk audio speaker cable. Tried plain 10guage cable (runs 5 min longer), but still same problem.
Has anyone else had similiar problems? Measured db levels with what amps??????????? Thanks, Paul

mantis

No,
you have some other type of problem.I assume your hooked up LFE to the sub's and not L+R split preouts?

That amp can handle just about anything you can throw at it...by the way awesome setup,I bet it sounds incredible.Did you get the silver faceplates??

Why it's clipping out??I can't see anything wrong with your setup,try this for the hell of it.Remove the line level from the pre amp,put the jumpers back in and run them where it shuts off.I'm also thinking about a heat problem,that amp need the breathe,I hope you don't have it in an inclosed rack, that will cause it to over heat.
Elan makes an awesome rack mount fan,it would sit on top of your amp and pull the heat out,works real good.You might want to consider a fan if heat is an issue.
Well thats all I got with the Info you supplied

RuSsMaN

You are using Polk 'cobra' cables? Having the dealer check the amp is probably a good starting point.... I wouldn't think that amp should be getting hot (maybe warm, but not HOT), driving 2 LSi speakers to 95db.....

Cheers,
Russ

pvabeach

Thanks for replys. I'll look into fan.
I put a hugh fan in front of amp and it ran fine. So seems to be cooling problem. Pulled amp out of rack and just sat on floor, still shut down. Yes, I have the , gees 15 + year old green and copper braided cables. I've read where they can affect amps, so I hooked up plain jane 10guage wire, same results. As far as "Remove the line level from the pre amp,put the jumpers back in and run them where it shuts off", hey I'll try it later this wk, but don't see where that would be issue? Dealer is contacting Rotel, we'll see what they have to say. Think I'll end up having to swap amp and try another one .
PS, I'm noticed when I first got LSI 25's, they sounded really terrible and low output 1st day, then opened up. After driving them real loud this weekend, noticed after several hrs, volume (Decible levels) increased serveral db over course of afternoon at same volume setting. Interesting. Thanks, Paul

RuSsMaN

Keep us updated, sounds like the LSi may do well after a break-in period....get those voice coils moving....

Cheers,
Rooster

pvabeach

I've emailed someone from polk, awaiting email response.
Seems lsi25's can dip as low as 2 ohms at 92 hz according to 1st email from polk. I have pre-outs hooked to 'line level' inputs on lsi25s. The line level inputs are not even pictured or discribed in the lsi25 manuel!! Thinking maby i should try and hook up to subwoofer inputs instead. This appears to bypass the LF crossover adjustment on speakers. Maby I'm getting some freq overlap or strange impedence/double filtering effect.......and that has something to do with amp shutting down. Awaiting feedback from rotel. May try swapping amp out. Thanks, Paul

gidrah

To me it seems like the Rotel is the culprit. I wouldn't expect it, but it happens to the best of 'em.

pvabeach

Well polk suggested for dx purposes to set my L & R mains to 'small' and set preamp crossover to 100hz. In two channel mode on rotel 1066 preamp, rotel 1095 amp still shuts down after 15 min. Taking amp to dealer tomorrow, hope thats problem.
ps the lsi 25's have 'main in' jacks besides subwoofer in jacks. Main in jacks are not pictured or described in current manuel.
Use of main in (vs subin ) jacks enables the crossover adjustment on polks for use with 'non-filtered' line level inputs.
Anyone else out there have LSI 25's??? What are you driving them with?? I'm listening at 12 feet from speakers with avg 95-96 db spl (c weighting/slow response) on rs sound level meter. Shouldn't these be attainable sound pressure levels?????
(no I don't listen at these levels for home theater). thanks,
ps they sound INCREDIBLY good while they run!!!!!!!! ( of course, I could turn volume down , but I shouldn't have to do that !!! No comparison to my SDA 1's . Imaging/detail so much more focused, no bitterness or shrillness. A treat!!! Paul

pvabeach

I purchased a separate Rotel 1080 amp to power the LSI 25's.
No problems driving them or overheating. Seems The 5 channel 1095 amp generates more heat as it has more 'boards' and 2 transformers. Paul

gidrah

Dang Rotels.

mantis

pvabeach,
strange problems you had.I think the amp might be defective.Id still swap it out for another.Or at least have the dealer test it.

The rb1080 is one fine **** amp.Very powerfull.I own the Rotel rb960bx,it's only 60watts @8ohms and It has no trouble running the Lsi 15's to 110db.It doesn't even get real hot, luke warm at best.I never listen to anything that loud,but I did test the amp to see how loud it could play before it distorted or the speakers gave up.At 110 db,both the speakers and amp played clean and clear.