View Full Version : Ohms
07-05-2003, 12:26 AM
I have LSI 25 series speakers with two tower, two on the side, two in the back, one center and 650 sub-woof. These are rated at 4 ohms. I have a Pioneer 47TX which is rated at 6 ohms. My amp is always running hot and sometimes will shut down. So we know we have an impedance problem. Is there anything that I can do to resolve this problem without putting resistors in-line or changing out the amp? I'm very limited in my knowledge of electronics and I'm getting different opinions from Polk and Pioneer as to a resolution.
07-05-2003, 08:20 AM
I have ran 4 ohm load speakers off the 47 with no problems.It's a THX ULTRA2 receiver with alot of power.Examle system I did was the Dynaudio Audience series.82 mains,120 center,42W's sides and rears and the sub30a.
One thing you can do is change the crossover point.I know you most likely used the Mcacc.Question at this point,where did the Mcacc setup the Crossover?,You can review the setting after you finish.You should set it around 80hz,not becasue the speakers should play anything under that but it will take some load off the internal amps.
As I think abou tit ,you might want to install a fan on top like the Elan Zfan.It looks like a piece of gear with 2 fans built in that suck the heat out of your recevier.Make sure you have good space around the receiver as the 47 gets hot all by itself with no load on it.It naturally runs hot.You must not put it into a closet cabnet or melt it you will.Very Important step here.Running 8 ohm load speakers causes this as well if it isn't properly vented.The Elan Z fan is your key here.It works wonders for hot running gear.
You called polk I assume,what did they tell you 2 do?You can always run your speakers in small and at 80 hz as I stated up top,run all subs in the system LFE by linking them all together in and out all the way around.I don't perfer this for music but I might yield Incredible results for theater.
Lets get your system straight as you wrote alittle confusing.......I assume you have Lsi25 mains,Lsi25 Surrounds,Lsi25 surround Back and a LsiCenter correct?
This is what I would do right off the bat is replace the surrounds and surround back with Lsi/FX for surrounds and Lsi7's for surround back.These speakers will run in small with awesome results for music or Movies.The room can be very large as you have plenty oif power with the 47a.
Now for a bit of reality check here.The Pioneer Elite vsx47tx is a very good almost flagship receiver.But there are better more current driving receivers or seperates on the market that will power your system with ease.Rotel is one of them,you'll loose alot of inputs and features,you don't have video upconverting at your level as only the 49 has that for Pioneer so that won't be missed.The Rotel rsx1065 and the rb1070 is your ticket.Or the seperates setup of the rsp1066 and the rmb1075,rb1070 combo for 7.1.Rotel has plenty of current to drive 4 ohm load speaker with ease my man......easy.
Anopther route to consider is B&K.The avr507 is a awesome machine with even more current drive.4 ohm load speakers don't even crack a sweat.B&K is all bout current.At it's price class it kinda sits alone....Seperates would be the ref50 with a ref200.7.
So there's some thinkinf for yeah.By the way in my opnion the Rotel and B&K smoke the Pioneer Elite is sound quality.I have countless hours on all these setups.Rotel and B&K is a pick em situation.You'll favor one or the other as they sound different.B&K offers more with features and custom install.Rotel does a great job at a price that can't be match by no one.
Review.......heat,small,LFE to all subs,swaping out the 47.......if need be or swapping out speakers........
Talk to me
07-05-2003, 08:37 AM
Phew - AWESOME advice. The amps will run much cooler at 80 Hz and this can be also excellent for music with the right sub.
I know you can attest (for example) the 9's with REL can be fabulous, even crossed at 80.
If the fan and the all-small/80 Hz fail to cool things down, consider that the Elite has such a nice pre/pro stage, why not simply buy a beefy high current external 5 or 7 channel amp and run it off the Elite pre-outs?
07-05-2003, 12:47 PM
If he did decide to go with adding external amps,then I suggest adding a B&K ref200.7 to the mix
07-07-2003, 12:36 AM
Thank you for responding to my post. Your assumption is correct on the LSI series. In checking the set-up, the speakers were set at small and at 80 Hz. I removed the two tower sub woofers from the receiver and only running the 650 sub, still hot enough to fry eggs on. So, for sure I need a fan, but my thinking now is to put the 47 up for sale and get a marriage for my speakers (the right amp).
07-07-2003, 07:03 AM
I'm still alittle taken about your problem.....
it goes into protection correct?
With everything set to small(I assume you did it manually instead of using Mcacc)you talked to Pioneer About this with not so great advice correct?????
If you do sell it off,you'll get good money and have a nice shot at another.......
07-07-2003, 08:10 AM
You are not he first person to run into this problem with a PE receiver and 4 ohm speakers. There have been a number of threads on various forums that cover the same issue. I had a Elite VSX-37tx that, although it did not shut down when driving my Lsi's, it did run very hot. You might want to double check the clearance around your receiver to make sure you have adequate ventilation. I believe Pioneer recommends 8" minimum above thr receiver.
My solution was to add a seperate amp to my HT that was capable of driving a 4 ohm speaker. There are a lot of great amps out there that can provide ample power for your Lsi speakers. I chose to go with an Outlaw 7100 (165w x 7 into 4 ohms) and have had great results. The Outlaw 770 is also a great amp for the price, if you need that much power.
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