Question about Amps in general

I am running the Polk LSI 15s with a sunfire amp(TGA5200) which gives them 400 watts into 4ohms. Would it make any difference in sound quality if I buy a TGA7401 which will do 800 watts into 4 ohms for the LSI15 and 400 watts into 8ohms for the rest of the speakers. All other speakers such as surrounds and center are 8ohm speakers.

Thanks for all your help

coolsax, a receiver's power supply also has to power the pre amp section, tuner, and amp's in it. whereby a stand alone power amp only has to do one thing.. and the power supplies only power for the most part one thing. the amps. so most of the current goes directly into amp section, then to your speakers.

also, a receiver listed at 105 wpc is not pumpting out 105 wpc all the time. given that a receiver has many duties.. your 105 wpc may in fact most times when your are using it could be as low as only 30 or 40 wpc. that can put a lot of stress on a receiver if you're driving difficult speakers or several speakers such as in a home theater set up.

this is a very simple explanation, there are other factors that come into play.. but this is one of the big reason's people like to use an external power amp. more power, cleaner power and more stable power and higher current being used.

An external amp as Danger described, will have more current flowing straight to the speakers. It's not only about wattage, its about the current behind it. There should be a subtle difference at the very least if you ran lets say your center channel only from your AVR. During passages in a movie where dynamics are all over the place, your center should sound a bit cleaner at higher volumes because there isn't as much stress on your AVR's internal amplifier section to drive a bunch of other speakers at the same time.

coolsax wrote: »

Danger- thanks that does explain pretty well but it leads me to a few more questions.

so with an external amp if its listed at 100w/ch, then it is more likely to actually output that amount due to only using the power supply to send the sounds to the speakers?

other than marketing what is the point of manufacturers putting that higher amount when the true wattage is much lower b/c of the dipersement of power from the supply?

So then If you were to use say a 100w/ch, 2 channel amp off of a preout and still had the surrounds and center off the AVR would then the true wpc on those speakers be higher than when you were running the fronts off the avr as well?

I'm just trying to wrap it around my mind b/c I've always known that the watts/channel on most HTiB were always misleading, but I assumed that when you started getting to a little bit higher end and a lot higher end stuff that it would be less so.

is the 30-40 watts you quoted a realistic number then b/c that would seem to be getting really close the low end of accepted watts for the speakers as they need a minimum of 20 in the Monitor series...

thanks

I"m not the best one to answer all your questions.. as I am still learning a lot of this about current and amps and watts myself.

Here is what I have been told.. if a amp or receiver is rated at say 100wpc it's not sending that amount of power all the time. Those 100wpc would be called into play if your speakers demanded it. A amp or receiver pumping out 100wpc all the time would likely melt from the intense heat build up.

For normal volume listening. whether it be music or a movie... there are peaks and valleys in the audio. When needed an amp may call up more power/current as need from the amp section. This is called headroom... you want and need a good amount of headroom (reserve current and watts) for it to handle those peaks in the music or movie.

If you go looking to buy a receiver.. you'll see listings that say.. 550wpc, 990wpc, I saw one that said 1305wpc. Yeah right.. if they built an amp that was multi-channel and each channel had 1305 watts.. that thing would be as big as a WV Beetle.

What they are doing is adding up all the channels, 2, 5, 6, 7, 9 etc.. together and coming up with those exceedingly high numbers for wpc. 9 channels x 100wpc = 900 watts of power right? So people look at this and think their receiver is capable of delivering 900wpc and then freak out when it shuts down and goes into protect mode or starts clipping. That's not to say an external amp can't go into protect mode or start clipping too.. they can, but they are more likely to have enough current and headroom in most cases.

So don't concern yourself with just wpc numbers.. they are very misleading and can vary from brand to brand. You will often times see Harmon Kardon receivers listed at only 80wpc.. and most people think they would be very underpowered.. but that's not the case.. they just measure their receivers output differently than say Onkyo or Denon.

If you are only running two or three speakers off a receiver is will be less taxing on it then say if you were running 5 or 7 off that same receiver.

30 to 40 wpc is low yes.. but even that isn't needed when listening to music or a movie. I have an old school Yamaha amp.. and it shows in analog dials a somewhat reference on how much wpc are being used when I listen to music. I bet you'd be surprised to know that in normal volume listening. the VU meters are only showing that I am only using about 3 to 5 wpc. Pretty low yes? So that again confuses people who think they need 500, 600 or more wpc and the only want to spend $199 for it at Wally Mart.

*I encourage anyone to correct or add anything to my long explanation, as you see fit if it's misleading or incorrect. Unless you're Doro, then you don't have my permission. :p

Oh man, don;t let the Pioneer ICE amp fanboi's read your post . They think the ICE amps can't be touched.

...now you might be thinking "but do I need an external amp?" No. You don't need an external amp; but since when has the hi-fi hobby ever been about what we need?

I just have to tag one question on here, while were on the subject of AMPs.
Would there be a huge difference in hooking up 1 545ii to each speaker?
Would each speaker get 100wpc at 8ohm, or 200wpc...probably a dumb question, but you can see what I'm thinking of already...

No kidding, very good choice. I've been kicking myself for a few months now for not pony'in up the dough for a receiver with pre-outs. I have these lovely speakers that are just begging for more watts.... and me without the cash to provide

...you know the old saying: "better to get what you want and cry once, than to compromise and cry twice"