amps/pre pros

[biorep]

can someone point me to some good reading on what an amp or pre pro is for and how would you hook one up to a a/v reciever? i know more power but if you had one would you buy a reciever with just a little power? i just dont get why i would pay 1000+ for a 130wpc reciever then add an amp, or prepro.
Thanks

 

[MDS]

An amp amplifies - nothing more.

A preprocessor is a combination pre-amp and processor. The pre-amp takes care of switching and routing input sources and controls the volume level along with minor audio adjustments like tone controls. The preprocessor is what decodes various audio formats and perfoms other signal processing chores such as bass managment- it is the 'brains' of the operation.

A receiver is a pre/pro, amp, and (radio) tuner all in one box.

You can use a receiver as a pre/pro if it has pre-amp outputs. You just connect the pre-amp outputs to an amplifier. A separate amp is usually more powerful than the amps in a receiver.

You can have a separate pre-amp and a separate amplifier and skip the receiver entirely.

When you go up in price for a receiver, you get better amps, alot more inputs, and usually a cleaner and more full featured pre/pro section. If you pair that receiver with a separate amp, you won't be using the amps in the receiver (except for certain cases where you only use the separate amp to drive some of the channels and let the receiver's amps drive the rest). You need to think hard about whether or not it is worth it to buy a > $1000 receiver if you are going to use a separate amp to drive all of the channels anyway. A better approach would be to buy the middle of the line receiver of a particular brand and pair it with a separate amp, unless you really need all the extra inputs of the higher end receiver. Just like everything else, the law of diminishing returns kicks in rapidly with audio equipment - as you go higher in the line you get incremental improvements for exponential increase in cost and only you can decide if it is worth it.

 

[mtrycrafts]

i just dont get why i would pay 1000+ for a 130wpc reciever then add an amp, or prepro.
Thanks

Well, audio, like other consumer markets, has its share of urban legends.
Once it starts, next to impossible to put to rest.

It would be a very rare case where you would think of increasing power with external amps. That is an issue of speakers and your listening level habits. And, one just cannot add a similar size power amp or it will not be doing anything more. you would need at least twice as powerful for a 3 dB spl level increase.

 

[j_garcia]

Actual output power vs claimed power can make a big difference though. A decent external amp rated at 100x5 is likely to produce more real world power than a receiver rated at 100w (or more), simply because amps are built to do one thing and they are usually better at it. It depends on the quality of each, of course.

My receiver was more than $1k, but the model below it didn't have what I was looking for. When I upgraded to low impedance speakers, even that receiver wasn't enough to handle the tougher load. Had I known that was my eventual path, I would have gone with the lower model receiver and a solid amp, which would have cost me about the same amount but yeilded more power.

You really only need to consider adding an amp if your receiver is strugging with a very large room or if you have tough to drive speakers. Otherwise, external amplification isn't realy a benefit beyond being able to turn it up louder. Louder is not the only benefit of plenty of power. Good clean power can help keep the speakers controlled better, giving you a cleaner, more clear presentation - again, this will only be apparent if your current receiver doesn't have enough power to drive your speakers at the level you desire, in your particular room.

 

[majorloser]

An amp amplifies - nothing more.

A preprocessor is a combination pre-amp and processor. The pre-amp takes care of switching and routing input sources and controls the volume level along with minor audio adjustments like tone controls. The preprocessor is what decodes various audio formats and perfoms other signal processing chores such as bass managment- it is the 'brains' of the operation.

A receiver is a pre/pro, amp, and (radio) tuner all in one box.

You can use a receiver as a pre/pro if it has pre-amp outputs. You just connect the pre-amp outputs to an amplifier. A separate amp is usually more powerful than the amps in a receiver.

You can have a separate pre-amp and a separate amplifier and skip the receiver entirely.

When you go up in price for a receiver, you get better amps, alot more inputs, and usually a cleaner and more full featured pre/pro section. If you pair that receiver with a separate amp, you won't be using the amps in the receiver (except for certain cases where you only use the separate amp to drive some of the channels and let the receiver's amps drive the rest). You need to think hard about whether or not it is worth it to buy a > $1000 receiver if you are going to use a separate amp to drive all of the channels anyway. A better approach would be to buy the middle of the line receiver of a particular brand and pair it with a separate amp, unless you really need all the extra inputs of the higher end receiver. Just like everything else, the law of diminishing returns kicks in rapidly with audio equipment - as you go higher in the line you get incremental improvements for exponential increase in cost and only you can decide if it is worth it.

Excellent advice!
I do agree, I would have to REALLY think about spending +$1K for a receiver. I was one of those guys who had to have the top-of-the-line equipment/receivers. Receivers (for the most part) lock you into one platform. When you go with separates the cost of the amplifiers is not lost. Even if you change processors the amplifiers can still be used and they seldom go bad.

For first time buyers, I always suggest putting the lion's share of your money toward the speakers. You can always upgrade the receiver later.

 

[biorep]

Excellent info, thanks! So a signal then would travel from:

Source to
reciever Preamp to
reciever Processor to
external Amp to
Speakers

?? Separate question: If I had an amp that was 200wpc do all my speakers have to be 200wpc?

Thanks again!

 

[biorep]

Hey MDS what part of Austin? I'm in SA, maybe when I finally get my gear I'll buy the beer and you can hook it all up

 

[majorloser]

?? Separate question: If I had an amp that was 200wpc do all my speakers have to be 200wpc?

Thanks again!

The short answer is "NO". I know this might sound wierd (and to put it simply), but it is better to have an amplifer more powerful than your speakers require. Not to say that they absolutely have to be more powerful, but it is better to have too much than not enough. You can cause more damage to a speaker driver by clipping (not enough power available from the amp). Also, all of your speaker do not have to have the same power rating. If you are using a receiver, in most cases it's important they all have the same resistance rating (ohms). On some brands of receivers this will cause an imbalance and possible damage. Some receivers even require 8 ohms or greater for all channels. Separate amplifiers will usually drive 4 or sometimes 2 ohm loads.

 

[j_garcia]

You don't need to have the same impedance on all channels. There's only one power supply in a receiver (as far as I've ever seen), so the total load is seen by the power supply at any given time. There's no imbalance to it. When it is an issue is if the power supply cannot handle that total load, and the more low impedance speakers you have, the more current is drawn and more likely clipping becomes. Impedance varies with frequency too, so what the power supply sees at any given moment is all over the place.

Most home receivers are rated for 8 Ohm use. Those with heavier duty power supplies may handle 6 and even 4 Ohm nominal speakers, but this will drive the amp harder than running 8 Ohm nominal speakers.

To add a bit to what majorloser said, the wattage rating on the speakers is a maximum unclipped rating, not a REQUIRED power level. A 200w speaker may run just fine with 20w, and in reality probably only needs about 10-15w to reproduce average listening levels. When you want more volume, that power consumption increases exponentially though.

 

[MDS]

Hey MDS what part of Austin? I'm in SA, maybe when I finally get my gear I'll buy the beer and you can hook it all up

North Austin - as far north and west as you can go and still be in the city of Austin. I rarely drink beer anymore, so make it Jim Beam and Coke and I'm there.