Axiom Home Page Forums General Discussion Home Theater pre-amps

Hello, I'm a newbie to home theater. What is the pupose of the pre-amp. Does it help with the sound? I have a onkyo 705. Would a pre-amp help with my home theater? thanks I have 2 m80'3, 350 sub, v150 center and 2 qs8's

The answer is no. Your Onkyo 705 already has a pre-amp. In fact, it has a pre-amp, amp, and tuner all in one box. The pre-amp section is what allows you to switch between different inputs (e.g. CD, DVD, and FM). The pre-amp section also adjusts the sound levels, does digital to analog conversion, and all the other sound processing.

If you did want to get an outboard pre-amp, you would also need to buy a separate amp or amps.

sorry i wanted info on a amplifier after the pre-amp. Could this make my home theater sound better?

Pat, it couldn't help unless your 705 wasn't adequately powering your setup for your use pattern. This is unlikely unless you're playing at extremely high sound levels in a very large room. At a comfortably loud average sound level your speakers use 1 watt or a bit less; brief peaks use much more, of course, depending on how wide the dynamic range of the material being played is. The 705 is a quite powerful amplifier and handles most use situations easily, so there's no good reason to spend more on a separate amplifier.

Patwho

Since you are running m80's, you may benefit from an external amp to power your front speakers. You didn't mention that when watching a movie or listening to music that your receiver is shutting down, but the receiver may be limiting the current. If the receiver is limiting the current then your m80's aren't sounding as good as they could. Onkyo's are supposedly famous (or infamous) for this current limiting according to Alan. If it were me I would get an external amp if I were driving m80's with the Onkyo 705. You don't have to go crazy and buy a 5 or 7 channel amp, I think just a couple Outlaw monoblocks would be more than enough. But, if you ever have your receiver shut down (going into protect mode) then you definitely need to get an external amp to power the m80's.

- Nick

Unless your having issues with your 705, it is totally fine with your setup, even 80's. The older Onkyo's had issues, but not the newer models. How big is your room, and really how loud (in SPL dB's) do you really listen to movies?

I do have seperate monoblocks for my 80's, but my room is 8,000 cubic ft, and I like it loud at times.

sirquack,

The reason that I suggested using external amplification to power m80's with the Onkyo is that a couple of months ago an Axiom owner reported having issues with his Onkyo 805 shutting down quite a bit with his m80's. This occured even when not driving them at very loud levels and I don't think that his room was huge like yours either. Furthermore, the power supply in the 805 is much beefier than the one in the 705. I own the 805 and am very happy with it. But, if I were to upgrade my m22's to m80's down the line I would definitely get some monoblock's to power the m80's even if they weren't shutting the receiver down all the time. This is because if I'm going to spend $1300 on a set of front speakers I want to make sure that I am getting all the performance possible out of them. But, that is just me. As you mentioned, if the original poster is not having problems with the 705 going into protect mode then there is no need to upgrade right now or ever if he doesn't want to.

- Nick

I understand, I really was not responding to your post, I was just next inline. I know historically Onkyo has been one of the brands not favored by Axiom. Years ago they did a lot of lab testing with the 80's and that was one brand that did not rate well.

The 80's are a very easy to drive system, that does not dip below 4ohms across the frequency range. To me it is amazing that any solid state AVR would have issues. I'm not really up on Onkyo's latest models, but have heard they have a better track record 80's and other 4ohm designs.

I've used my Denon 2805 to drive my 80's to levels most people would fine satisfying. In reality, your only using a few watts with dynamic peaks from time to time. Any 100 watt AVR will accomplish this task.

But like you I love my Odyssey Khartago Mono's. The 80's never sounded so good...

Nick, the reason for my previous post was that the 750 is a superb receiver and any concern about "current limiting" has no factual basis. If the impedance setting is left at its high setting, regardless of the impedance rating of the speakers, no limitation of the voltage from the power supply section takes place, and if the voltage isn't limited neither is the current or power which it controls. No subtle loss of performance takes place if the receiver doesn't shut down and none should be imagined; it either supplies the power or doesn't.

Hey Pat, confused yet? M80s are easy to drive, but at 4 ohms they shut some (quite a few) receivers down. The 705 is a well built receiver and will have no issues with the higher current draw associated with a 4 ohm speaker, but this guy had problems with his 805 shutting down all the time.

Both of these statements are contradictory.

I think the first is easy to resolve. I think a lot of people equate efficient (fewer watts to produce 75db at xx distance) with easy to drive. However, given that the M80 has a habbit of shutting down certain brands of receivers (under ??? conditions) suggests that this is not true. I think it would be more accurate to describe the M80s as efficient, but particular.

As for the second one, who knows. That particular receiver could have been shutting down for any number of reasons including an inability to handle the current load.

OK, everybody feel free to poke holes in my logic.