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What is a pre-amp?

 

New member
Username: Nathanp

Atwood, IL USA

Post Number: 3
Registered: Jul-05
What is a pre-amp?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 4640
Registered: May-04


http://diyaudiocorner.tripod.com/def.htm

http://www.ecoustics.com/electronics/forum/home-audio/56618.html

http://lp2cd.com/audio_terms/a/index.html

http://www.stereophile.com/reference/50/index.html




 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 696
Registered: Sep-04
An amplifier can be split into two main parts - the preamp and the power amp.

The preamp is the signal processing part of an amplifier. This means it's the section of the ampthat allows you to plug in sources such as tuner and CD player. It's also the section that allows you to change volume and possibly to change treble and bass settings. So it's a glorified switch with volume pot.

The power amp is the section of the amplifier that drives the speakers.

Now traditionally, as you went up the amplifier hierarchy, one way of deriving better fidelity was to separate the two sections of the amplifier. By separating the preamp from the power amp, you could design a dedicated power supply to manage the electronics dealing with the more delicate signals without interference from the noisier power amp circuits. In some cases (Naim Audio and Nytech for example), even the power supply was separated into another case to reduce the noise in the preamp further. Preamps can also be 'passive'. These do not need a power supply since the components (basically a quality switch and a volume potentiometer) are being driven directly by your sources. Theoretically this is the best way forward but in practice there are quite a few limitations which mean the passive preamp remains relatively rare.

When we talk about preamps we usually mean preamps in a separate case. This requires a separate power amp to drive speakers. An amplifier with both pre- and power sections in it is either just called an amplifier or, more accurately, an integrated amplifier.

It used to be fairly obvios where integrated amps stopped and separate pre/power amps started, but in the last 5 years this line has gone with more highly specified, better quality integrated amps appearing at much higher quality (and expense) levels than had ever been imagined in the past. This is partly due to costs (extra packaging and casings are a wasteful luxury in this day and age) but also due to living constraints where many people simply won't accept between 2 and 4 boxes for a single amplifier in their modern rooms.

I hope this helps.
Frank.
 

Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 697
Registered: Sep-04
Incidentally, preamps tend to be the province of 2-channel stereo. Home Theatre preamps, which can process all the surround options under the sun but can't drive speakers directly, are often called processors. However, this is not a hard and fast rule.

Regards,
Frank.
 

Gold Member
Username: John_a

LondonU.K.

Post Number: 3496
Registered: Dec-03
"So it's a glorified switch with volume pot." Yes!

With 2-channel stereo one can connect most sources, today, directly to the input of a power amp. Does not work with phono, however. A simple, passive, input selector switch allows one to choose between different sources.
 

New member
Username: Falcon147

Post Number: 1
Registered: Apr-08
Q.
1. Will I double the power using two identical amps preamp out of amp 1 out to amp in of amp 2 and preamp out of 2 to amp in of 1 without frying out everything<<<<

If not do I use the amps in a crossover situation in order to double or add power? Are there any other simple otions without spending moo la la.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 12436
Registered: May-04
.


Theft?
 

New member
Username: Carolinablues

Post Number: 2
Registered: Jun-08
I have an Onkyo 606 AVR - If I use the zone 2 out to another amp, is this acting as a pre-amp?

Would this provide better sound quality (SNR), than using a AVR switch like this one(below) which has a SNR of 64db?

Cables To Go - 40324 - 3-Play Component Video Digital Audio Selector

http://www.amazon.com/Cables-Go-Component-Digital-Selector/dp/B000AM3U2I
 

Platinum Member
Username: Nuck

Post Number: 10464
Registered: Dec-04
CB, the receiver is the preamp.Simply supplying a signal to a power amplifier will result in an amplified version of the signal from the receiver.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 12779
Registered: May-04
.

A receiver is not a pre amp - a receiver has a pre amp along with a tuner and a power amplifier all on the one chassis that's called a "receiver". I can't imagine your Zone Two output running into a power amplifier would provide better sound quality than your existing receiver unless your receiver is not capable of driving your speakers.


What exactly are you trying to do on the cheap?

.
 

Platinum Member
Username: Nuck

Post Number: 10476
Registered: Dec-04
Sorry, the rca output for these zones output from the receiver is acting as a preamp.

And yes, what are we trying to do on the cheap?
 

New member
Username: Carolinablues

Post Number: 3
Registered: Jun-08
Thanks for the input!

I have multiple inputs in one room and distribute them around the house(inside and outside) to various receivers and amps (some are t-amps).

Presently, I use a switch (similar to the one previously mentioned (64db SNR).
Then onto a Distribution Amp(like this http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=180-007), then onto the amplifiers.

I just got this new receiver with a Zone 2 out. I figured if the AVR zone 2 has a better SNR than the switch, I could get a better quality signal at the end point. I can't seem to find any specs on the zone 2 outs on any receiver.

(Basically wanted to use my zone 2 as a audio switch with better SNR than 64db)

This is for audio only.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 12786
Registered: May-04
OK, you got me confused!

First, SN specs are not a reliable way to judge the quality of a component.

Second, your system sounds like a switching nightmare - and for no good reason. If I understand this correctly, you are running your sources in this; http://www.amazon.com/Cables-Go-Component-Digital-Selector/dp/B000AM3U2I, and then from that into your receiver.

Then you are running your receiver's output(?) into the line distribution amplifier and then into your multi-channel amplifiers?

You need a receiver with sufficient inputs to do away with the 3-Play Component Video Digital Audio Selector. And with a Zone Two output you shouldn't need the line distribution amplifier.
 

New member
Username: Carolinablues

Post Number: 4
Registered: Jun-08
Ok. Lets focus.

All my sources are in one room. You are right, I would not need this mess if I only listen to them in this room. Plugging them onto my old receiver does not give me access to the audio signal in different parts of my house.

I use my Nokia n770 and Nokia n810's media streamer combined with Tversity to control multiple media servers. Plus I can use these nokia and run VNC and/or rdesktop to control any of my computers with audio.

Using these babies, I can control anything I need to listen to from anywhere in the house. They actually become the best audio remote control you could ask for, since you are running XP in the palm of you hand. Or running their media streamer and controlling media servers through upnp is really cool.

For example I can be on the deck/bedroom/garage/kitchen,etc with my nokia and have complete control over what I listen to.

Therefore, I need to distribute the signal from the room with the sources to the rest of the zones.

Up til now, I used the AV switch/ and the distributed amp for this purpose.

I was just wondering if the new receiver's zone 2 output would have a better "quality" than the switch I am presently using.

This would remove much of the switching nightmare, but will it improve the audio signal?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 12787
Registered: May-04
.

Will it improve the signal sent to the deck/bedroom/garage/kitchen,etc?


Probably not in any noticeable way. The signal you are sending right now would have to be quite lousy before I would day you will gain quality by using Zone Two outputs for those areas. Like I said, SN spec is not a good judge of quality.


What sort of "quality" upgrade are you looking for?


.
 

New member
Username: Carolinablues

Post Number: 5
Registered: Jun-08
Just trying to figure out if I am going in the roght direction.(improvement or not).

If the SNR is not important, than what?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 12794
Registered: May-04
.

Don't know! Specs are made to be manipulated. Weighting systems take S/N ratios anywhere the person taking the spec - or printing the spec - wants them to go. When you get down to judging things like switches there aren't good rules to follow. You can take one apart or find out what ic's and so forth the manufacturer uses and then research those components but you're getting pretty far into the deep end of the pool at that point. The best answer is usually buy one and, if it sounds like pounded-puppy-poo, take it back. The issue here for me would be just how much "quality" you expect in these remote areas of the kitchen and so forth. These are typically background music listening areas and don't normally require much in the way of "quality", just that the sound doesn't drive you from the room. And, if it does, it probably isn't the switch that's at fault.


.
 

New member
Username: Carolinablues

Post Number: 6
Registered: Jun-08
The quality seems to be fine.

For what is is worth, I also used a different AV switch, and I noticed the sound wasn't as good as it was with the 3-Play switch(which also has optical input/output).

I just thought that there was a way to quantify these things, but after looking for specs it seems to be hard to nail down.

Thanks for the help.

Rock on.
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