Receiver vs. Pre-Amp What's the Difference

G

Gibransound

Audiophyte
I must appologize for I am an aspiring audiophile so bear with me. I have tried to find the answer but I just dont understand it. What is the difference between a receiver and a pre-amp? Why? Because I have an Onkyo TX-DS696 receiver and I want to know if the sound can be improved even more by adding a pre-amp or anything else that someone might want to suggest.
Thanks
 
R

Ryo_Ohki2

Audiophyte
Preamps is usually the control center of your stereo system before the signal gets sent to a amplifier. The receiver is also a control center but a built in amplifier. So putting a preamp in series with a receiver would not occur. People go the preamp route to keep all their components seperated so each part is dedicated for specific functions of your stereo system. Receivers are combining the technologies together. Some people think component gives the most accurate sounds since every part is dedicated to do the best that it can do, others think receivers are just as good. Well that's my understanding. Hope that helps.
 
WmAx

WmAx

Audioholic Samurai
Gibransound said:
I must appologize for I am an aspiring audiophile so bear with me. I have tried to find the answer but I just dont understand it. What is the difference between a receiver and a pre-amp? Why? Because I have an Onkyo TX-DS696 receiver and I want to know if the sound can be improved even more by adding a pre-amp or anything else that someone might want to suggest.
Thanks
Unless you you need a special circuit routing which is not possible with the reciever --- there is no reason of which I am aware to expect actual improvement, audibly, by using seperate amplifier/preamplifer components.

I have rid myself of my 'audiophile' amplifier(McIntosh MC754) and pre-amp (Adcom GFP750)components recently in favor of a used Harmon Kardon AVR55 reciever that I found at a local GoodWill thrift store for about $25USD. No noise or other problems are present. I did need some custom routing of some of the internal circuitry, so I did open it up and make some minor modification to suite my purpose(s). I prefer the reciever as a preamp due to the digital indicator readout of the volume setting and the built-in phono preamp, which I might use if I decide to purchase a phonograph to play my record collection. Besides, I recently went full-active on my 3 way speakers, so I would have had to purchase an additional amplifier. I am using 4 of the reciever's 5 internal amplifiers(for midranges and tweeers) along with an external amplifier(Adcom GFA555) for the woofers. I recovered much money in selling and saved money by not having to buy another amp. :)

If I believed that any 'degradation' was present due to my 'downgrading' to a reciever -- I would not have done this. So, at least you have my view of the situation.

-Chris
 
crashguy

crashguy

Audioholic
Think of the pre-amp as the controls and switches. The amplifier component (if a separate comonent, it is called a "power amp") is similar to the engine of a car.

The whole car would be the receiver; it contains all of the parts necessary to play music or movie sound. This may simplify:
1) It is called a "receiver" if it contains a AM/FM radio receiver (tuner), a pre-amp, the processor and a power amp
2) It is called an integrated amp if it conatins the pre-amp, power amp and processor and NOT the radio tuner
3) It is called a pre-amp if it is a receiver without a power amp section and requires a power amp(s) to run speakers
4) It is called a power amp if it only supplies signal amplification to run the speakers

While you will hear many audioholics talking about adding a power amp, they do this more as a "want" than a "need". I am included in this category. Unless you have specific problems such as needing to fill a very large room with sound, your speakers are inefficient (not a sign of poor qulity, just design choice), or your speakers have low impedence, you will likely not NEED a power amplifier. Does that mean you won't WANT a power amplifier to add to your system? Not at all.

To see if your receiver is able to be connected to a power amp to upgrade the power, it must have what are called "pre-amp outs". These are connections which basically bypass the internal power amp, and feed the unamplified signal to an outboard, separate power amplifier, ideally one of better quality than the internal one in the receiver.

If you think of it in terms of just good ol common sense, a power amp costs $1000 and weighs 30 lbs. It is designed to power 2 speakers, and that is all it is designed to do. Now you have a receiver, costs $700, and is designed to power 7 (or more) speakers. Which do you think should sound better and be more powerful??
 
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R

rschleicher

Audioholic
audio systems basically have two stages of signal manipulation, a pre-amp, followed by a power-amp. These might be in separate boxes, or else combined into an integrated amp. If you add a tuner to an integrated amp, then you have a receiver. The above terminology dates from stereo and even mono days, but is also applicable to multi-channel A/V systems.

Basically the pre-amp stage does the signal manipulation/processing. In the old days this was basically just tone, balance, and volume controls, but might also include various filters, as well as phono input equalization and level adjusting (sort of a pre-pre-amp, raising the level of a phone cartiridge's couple of millivolts, to the 150 millivolt level of other analog "line-level" sources). Nowadays you also have decoding of digital source inputs, digital signal processing of sound fields, etc., and other functions that might be considered to be part of the pre-amp, but are sometimes viewed as separate signal processing functions. (In either case, they are before the power-amp.)

Pre-amps may provide a little voltage gain, but they have very little capability for driving speakers. Basically, they expect a relatively high-impedance load, and also typically have a pretty high internal source impedance (since it doesn't matter when you are driving a very high impedance load).

Power amps provide the oomph to actuall deliver power to your speakers. They present a nice high impedance back to the pre-amp (meaning they don't require much power from the pre-amp, nor do they load down the pre-amp). In turn, they have a nice low internal source impedance, so that they are capable of effectively delivering power to the low-impedance load presented by a speaker. A low source impedance also means that the frequency response of the amp will not be affected by the complex impedance versus frequency characteristic of the speaker. Power amps provide gain, and the capacity to deliver power to low impedances, but don't modify the signal in other ways (at least not intentionally).

Many receivers provide external access to the pre-amp outputs for each channel, just prior to the power-amp stage for each channel. Thus, if you want to use a larger external power-amp, you can use just the signal processing and pre-amp functionality of your receiver, and get the main amplification from the separate power amps. Since many multi-channel receivers are incapable of providing full rated power for all channels simultaneously, a common arrangement is to use separate power amps for the fronts, or maybe the fronts plus center channel, while continuing to use the receiver's internal amps for the surrounds, back-surrounds, etc.

A smaller number of receivers also provide access to their internal power-amp inputs, as well as the pre-amp outputs (you will usually see the two connected using little metal jumpers). This enables you to use a separate pre-amp/processor (or pre/processor) with your receivers power amps. But, since in most cases the "weak link" of a receiver is its power amps, rather than its signal processing, it is much more typical to use the receiver as the pre/processor, and separate power amps, than the other way around. (Also, the analog multi-channel inputs of the receiver allow you to use the decoders of your source, rather than the decoders built into the receiver, providing part of the flexibility provided by having power-amp inputs.)

Guitar players are very familiar with the concept of pre-amp and power amp, as guitar amps typically have separate gain/volume controls for both stages. If you want a clean sound, you keep the pre-amp volume/gain setting fairly low, and use higher gain in the power amp stage to get the loudness you want. Alternatively, if you want a distorted "fuzz" tone, you crank the pre-amp gain/volume way up, so that you are getting clipping of the signal being fed to the power amp. Then, you use a relatively lower gain/volume setting of the power amp (for the same perceived loudness as with the clean sound). Overall loudness is the same in both cases, but the intentional overloading of the pre-amp gets you a nice distorted rock guitar sound. (Or you can set both knobs to "11", a la Spinal Tap!)

(As an aside, tube guitar amps exhibit a fairly soft clipping, that generates a lot of second harmonics and a nice warm distortion. Transistor amps tend to clip "hard", which generates more 3rd-order harmonics, which tend to sound overly harsh. So, some transistor guitar amps actually use more complex signal processing techniques to artificially generate tube-like clipping, instead of real transistor-like clipping, in order to get a more vintage-sounding distortion.)
 
G

Gibransound

Audiophyte
Thanks

Wow, thanks for the info. It feels great to finally understand. :)
 

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