What is the role of a preamp?

[BLASTO]

Hi guys,

Iam perplexed with the role of a preamplifier in the audio setup. Online search results in some arbitary points referring to volume cotrol.

If it is as simple as a volume control, why are they not integrated in a CDP itself?

Also why does a preamp cost as much as the power amp itself in a pre-power combo? What does it do actually? At the most, the processed signal can be only as good as the original signal from the CDP? Does the pre-amp give any artificial characters to signal?

Also some old CDPs from marantz DO come with volume controls. Do they have a preamp built in? Can they be directly connected to a power amp?

Also, when we purchase an integerated amp, how much percentage of the money goes into preamp and how much into the power amp?


When we are trying to reproduce the actual recording, doesn't preamp affect the purpose by altering the signal?

 

[saj2001ind]

thats a good question, I would like to know that too

 

[Audiodoc]

Basically preamplifiers have three functions;

1. Impedence matching.
2. Source selection with clean adequate amplification to line level. Although most sources do that to begin with. But phono etc low level ones need amplification.
3. A very good volume control.

I agree that they should be cheaper and the manufacturers are squeezing out our hard earned money. The pass B1 clone on this forum is great.

 

[heliumflight]

In my experience Pre-amp adds tonal qualities to the sound and Poweramp adds the muscles.

 

[srinisundar]

This topic may help you to an little extent and I have gone thru these pages while going away from Integrated amplifier.

Preamp: Buying Guide

Preamps Explained

Buying Guides: Preamps Buying Guide | Musician's Friend

 

[jls001]

Amplification in audio happens in two stages or three stages. All line level sources that produce a nominal 2.83V output need two stages - a (line level) preamplifier, followed by a power amplifier. Phonographic playback devices produce much lower signal - usually less than 10 millivolts. So they need one stage of amplification to bring to line level voltage of 2.83V. After it reaches this voltage, it can be plugged into a line level preamplifier. The output of this preamplifier can now be amplified further by the power amplifier.

Now, why split amplification into two (or more) stages? Besides the answers already given in Post # 2, it has to do with the difficulty of obtaining a large enough gain using a single stage of amplification. Hence the gain of the amplification chain is split.

 

[Flash]

Ok, thats a lot of questions .

But in short.

Yes Preamps add tonal qualities to the sound signature

for example.
Connect a poweramp to the preouts of an AVR lets say Denon .
The overall sound signature will not sound very different from the Denon AVR playing by itself. Yes the added power will benefit the speakers in question however the sound signature would stay pretty much the same.

Do the same with a lets say NAD integrated. add a power amp of lets say a Onkyo/ Cambridge Audio which is basically bright. However the preamp section of the NAD would add warmth to the final output.

Now when you take an dedicated preamp into question they are designed for a specific duty. Inputs / outputs/ etc etc. Its just not a volume pod.
The entire circuitry with the torodial PS in a preamp is geared specifically to give a clean output and do it well . with as less crosstalk , Good S/N ratio /Channel Separation etc etc

That's why Preamps can run into several thousand $.
Ever wondered why good Tube preamps are so sort after. well because most of us love the tubey sound etc etc etc

And that's why the cost.
The same also goes for standalone DAC's vs DAC's inbuilt in AVR's / IPOD's / Sound cards etc etc. most good dac's cost more than integrated amps and AVR's

 

[doors666]

if you dont need the gain and have only one source, you dont need the pre-amp, just a pot will do right? after all, in most of the cases, no coloration is better than any coloration (except tube i guess).

 

[miroflex]

Hi,

jls001 has explained the main reasons for the need for pre amplification very succintly.

Regards.

 

[kvinodkumar]

Hi,

I thought of asking this question... Use of Pre amp and power amp. Thanks to Blasto for starting the thread and jls001 for the information. Thanks again!!

 

[reignofchaos]

A preamp is used for initial voltage amplification. This is needed so that the power amp which basically amplifies current works in the most linear section of its output graph. Plus it gives the functionality of switching between multiple inputs without having to change connectors. Some folks unfortunately also use a preamp as a tone control to flavour the sound in the way they want it to be. However this is not what a preamp is supposed to do.

If you feed line level output into the power amp, unless the input sensitivity of the power amp is sufficiently high, you will completely lose on dynamics and micro detail.

Then there's the question of gain - how much gain does one need from the preamp - typically a gain of 12dB is sufficient for most power amplifiers but some may need more or less. High end pre-amplifiers allow one to tweak the gain in dB to whatever suits your fancy. Do note that this is different from volume control. Some of them even have an HT bypass mode that just outputs the input signal to the output without any gain. This is useful if for example you wish to have the same setup for HT and Stereo without losing out on either of those functions.

Do note that some CD players actually allow you to connect directly to a power amp and have a gain stage which can directly connect to a power amp. However most of these are bloody expensive - especially if the volume control is analog.

 

[hemantwaghe]

That leaves question of using marantz cdp as pre amp ....in fact
Can your music pc be used as pre amp?Esp taking output from premium soundcards like ESI Juli@ ( balanced) and feeding it directly to power amp?

 

[Flash]

That leaves question of using marantz cdp as pre amp ....in fact
Can your music pc be used as pre amp?Esp taking output from premium soundcards like ESI Juli@ ( balanced) and feeding it directly to power amp?

A good soundcard can certainly be used as a preamp.
However with most soundcards.
1.you will not be able to add on more sources in order words your PC will be the only source you will not be able to add on more sources which could be a problem
2. Startup time for a PC could be a niggling problem

Well coming to the CDP.
Why not add a volume pod it to a CDP.
With Hifi
Separates as in
Amp + Preamp + AVR + CDP + DAC + PC + Turntable + etc etc give the Hi fidelity sound which we audiophiles crave for. Since each of the components are designed specifically for doing a sngle role as opposed to multiple.

And that is probably why none of us every talk about mini Hifi's that are so abundant everywhere like the Sony's / LG's? Philips.

They have everything in one box CDP + AMP + Preamp etc etc
So basically Jack of all trades and Masters at none, unlike separates

 

[spirovious]

That leaves question of using marantz cdp as pre amp ....in fact
Can your music pc be used as pre amp?Esp taking output from premium soundcards like ESI Juli@ ( balanced) and feeding it directly to power amp?

Why not,you can control volume of music PC with remote too.Like I use.

A good soundcard can certainly be used as a preamp.
However with most soundcards.
1.you will not be able to add on more sources in order words your PC will be the only source you will not be able to add on more sources which could be a problem

When you have PC,ideally no need to add another device unless you need to connect TV to poweramp(Tv tuner is another way though).I have HTPC as music PC.Here any format can be played if one installs bluray drive.In my case ,my D2X accepts digital input too which can be looped back to power amp.Here SC acts as DAC.

This is a really nice price. Who are the dealers of Rythimik in India, if you happen to know?

 

[gobble]

A good preamp is like Lingerie. It makes the content and playback more revealing, allowing the man a deeper insight into the source material, and paints a vivid seductive picture of the artists original intent, and keeps him thirsting for more ... A good preamp titillates the listeners senses hyeah:

I hope this post explains things as it really matters, in a format more understandable to the lay audience than all the previous needlessly technical and geeky explanations

--G0bble

 

[srinisundar]

A good preamp is like Lingerie. It makes the content and playback more revealing, allowing the man a deeper insight into the source material, and paints a vivid seductive picture of the artists original intent, and keeps him thirsting for more ... A good preamp titillates the listeners senses hyeah:

I hope this post explains things as it really matters, in a format more understandable to the lay audience than all the previous needlessly technical and geeky explanations

--G0bble

Purpose of Pre-amp cannot be explained more than this

 

[doors666]

A good preamp is like Lingerie. It makes the content and playback more revealing, allowing the man a deeper insight into the source material, and paints a vivid seductive picture of the artists original intent, and keeps him thirsting for more ... A good preamp titillates the listeners senses hyeah:

--G0bble

See, even he agrees, no preamp is better than any preamp:lol:

 

[square_wave]

A good preamp is like Lingerie.

Agree !

It makes the content and playback more revealing, allowing the man a deeper insight into the source material

This is not possible. The best it can do is NOT to add more veils in the most important areas.

and paints a vivid seductive picture of the artists original intent, and keeps him thirsting for more ... A good preamp titillates the listeners senses hyeah:

Agree ! The best examples are capable of doing this.

 

[heliumflight]

A good preamp is like Lingerie. It makes the content and playback more revealing, allowing the man a deeper insight into the source material, and paints a vivid seductive picture of the artists original intent, and keeps him thirsting for more ... A good preamp titillates the listeners senses hyeah:

I hope this post explains things as it really matters, in a format more understandable to the lay audience than all the previous needlessly technical and geeky explanations

--G0bble

Nobody beats the gobble man with words.

 

[mikehcm]

HowStuffWorks "Pump It Up" Hope this helps.