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JD1

The job of a pre amp

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Hi, have a question about the role of a pre amp. I have an amp running my speakers with no pre amp between it and my opponent. Does the pre amp contribute to the quality of the music and shape the base and highs or is it there mainly to control volume and direct the flow from the different devices that feed into it. Will it improve the sound of the sound from the power amp. I always had the feeling it was also meant to do some thing to the signal before it was amplified. Any help would be appreciated.

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Sorry  its not my opponent, but my oppo. Dam spell checker

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You are running the oppo directly into a power amplifier?

 

This means the Oppo is acting as the preamplifier in a sense but is simply an attenuator with its internal volume control, it simply drops the output signal. I found with mine this had a background noise, occasional scary pops and all-round just not great sound.

 

A preamplifier typically gives the signal additional gain prior to reducing the signal level, and generally will improve sound quality between these components (assuming quality is equal to the rest of the gear). Also of course gives extra inputs etc. 

 

If however your "amp" has volume control on it, it will likely have some sort of preamplifier stage internally along with the actual "amplifier" so is both items in one box.

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Posted (edited)

Tricky question and just warning you you'll get far extremes of opinion. In my experience preamps colour the sound in a way that somehow sounds more natural in every way. The straight wire proponents would tell you that it is artificial and damaging the signal and any change it makes to the sound is wrong. That's not been my experience at all. A good preamp adds body and volume and microdynamic intensity to the sound and solidifies what otherwise sounds thin without it. If it's due to colouring the sound, then so be it, since it sounds better. Source components rarely if ever have as good output stages as a real preamp so a real preamp "drives" a power amp better.

Edited by Ittaku

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The oppo is acting as the pre amp and can control the volume. I was of the opinion that the it would add to the signal and improve the sound if it was a good pre amp. I do not have a lot of knowledge in this area so was not confident that this was the case. Pre amps seem so expensive as a separate purchase that they must surely have an important role to play. I am in the throes of deciding wether to purchase a pre amp or not and if the expense is warranted. Thanks for the relies.

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Food for thought, but bear in mind he's trying to sell his preamp too ;)

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41 minutes ago, JD1 said:

Does the pre amp contribute to the quality of the music

Only in the event that the source and amplifier directly connected, are not well matched to each other.

 

Some power amplifiers are hard to drive .... some sources have poor quality signal amplifying stages ..... sometimes the electrical impedances of the source+amp are poorly matched ..... and sometimes there is too much (or rarely, not enough) gain in the source+amp.

 

Obviously preamps can offer other features like input switching, balance, tone, phono, effects loops, etc.

 

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I've experimented with many Sources direct to Power Amp and every time I put in a good quality Pre-Amp, the "Magic" returns.

 

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This has always been a cunandrum for me!

Giving that the preamp is well matched to the source and the the power amp,

who is to say the preamp is not coloring the sound in some way? 

Without extracting the recorded sound through some electronic device, it can not be known what it might sound like.

A pre amplifier to me is like an amplifier in the sense that the information extracted has to travel through various components and like an amplifier they alter the sound in way that suits our taste.

How far it diviates from the recording is anyone's guess.

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The main function of a preamp is to control volume and switch inputs, some just do it better than others, but an oppo straight into an amp is probably a decent cheap option :)

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2 minutes ago, Gremrock said:

The main function of a preamp is to control volume and switch inputs, some just do it better than others, but an oppo straight into an amp is probably a decent cheap option :)

Yes, that is stating the obvious 😌

I am just intrigued on how some will say that a pre amp is supposed to be a wire with gain. You won't hear anyone say an amplifier should only be wire with gain to drive speakers. Most will accept that amps have their own sound.

 

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Posted (edited)
43 minutes ago, Ihearmusic said:

This has always been a conundrum for me!

Giving that the preamp is well matched to the source and the the power amp,

who is to say the preamp is not colouring the sound in some way? 

Without extracting the recorded sound through some electronic device, it can not be known what it might sound like.

A pre amplifier to me is like an amplifier in the sense that the information extracted has to travel through various components and like an amplifier they alter the sound in way that suits our taste.

How far it deviates from the recording is anyone's guess.

For decades I was pursuing as "neutral as possible" thinking I was doing the best thing I possibly could for audio reproduction. It took me a long time to accept that this was actually bogus and that no recording is a perfect facsimile of the original sound and that hi-fi has to do as good a job as possible of trying to reproduce the original experience but that "perfectly neutral" was, in fact, impossible. Given the magnitude of distortion from speakers and the limitations of the actual room you're listening in, the job of amplification is to try and recreate that original performance within the confines of what reproducing sound in a flawed environment requires. The best amplifier manufacturers in the world concede they all add distortion to the original information - but they're trying to make it so the distortion that is added actually improves the experience rather than worsens it. No one is aiming for 0% distortion any more as that leads to horrible sounding hi-fi (ever wonder why?) That's not to say they're trying to set distortion levels high; only to make it beneficial instead of detrimental. To that end, I find that whatever it is that preamps are doing in the signal path - and it's likely to be a combination of being very robust at providing an unwavering signal into the power amplifier AND a certain amount of harmonious distortion - when done well it sounds better than without. It could well be that we need to add just the right kind of distortion to the sound of a recording to make it sound more real by the time it's coming out of a loudspeaker.

 

Either way, if you have the time, budget, and opportunity, audition a good preamp and see for yourself. It's very hard to go back to not using one.

Edited by Ittaku

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Of course they have their own sound, but the general gist is that the most neutral measures the best. Whether we agree they SOUND the best is the issue. Some of us like a little added warmth and coloration. 

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Posted (edited)

Choosing the right power amp and likewise speakers particularly observing sensitivity and resistance loading, can solve many

problems that relate to whether a preamp is needed at all. 

 

Ideally you want to hear the source component and what it is capable of, and not to have to re- amplify the source,

Sadly there is yet to be any amplifier that fully preserves what your  source component already provides.So re amplifying it,

is not going to make it any better.   

 

If we look at efficiency of audio systems owners of Klipsh horn loaded speakers, have already nearly solved the need of unnecessary amplification, by using very efficient speakers. Their systems benefit from the amplifier not being strained

at all, most horn loaded speakers only need 20 watts to drive to very high sound pressure levels. Most power amps

offer outstanding figures of low distortion when driving just 20 watts. In other systems though with inefficient

speakers, amplifiers are strained to deliver the same levels and invariably start adding unneeded distortion. 

 

So with this in mind the wrong approach would be to purchase a power amp with 3.5 volts sensitivity for full output and have

resistance loading of 10,000 ohms. with these figures the power amp requires the source component to be further amplified.

 

 

The better choice is a power amp with much better sensitivity and resistance loading,  meaning you now have enough sensitivity

already in the  power amp exactly where it is needed. 

 

You then will find the freedom to just attenuate the audio signal as a volume control relieving the need for pre amplification. 

Today's modern components, like dedicated phono stages, and DAC's and CD players offer outstanding specification, to make

attenuation your best choice to connect with the source.

 

Edited by stereo coffee

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Posted (edited)

A bit like Groundhog Day this question ...

 

The first thing I would ask the OP is do you have more than one source component? If so, you probably need a preamp to switch and control volume between them.

 

Secondly, it is a complete Lottery out there in terms how power amps perform on their own, when connected directly to a source component. My experience is that sometimes you can fluke it and it can sound very good that way, but more often than not a  good preamplifier will bring something extra to the party ...a sense of realism, vivacity and a forward projection to the music (as different from a flat lifeless sound that makes you think the music is contrived by electronics).

 

I don’t agree with Ittaku/Con that preamps necessarily introduce coloration. This is an assumption rather than fact. With my own Supratek Cortese valve preamp (the latest circuit), it brings greater accuracy to the situation. Why do I say that it is more accurate, it’s because I can hear more fine details in the recording, better timing in the music, a real sense of the venue and a bigger soundstage. How can all of this be put down to coloration or distortion - when you are actually hearing more detail and music as the musicians originally intended?

 

Consider also that if you choose carefully, the preamp can be a pivotal component that passes on its goodness to the rest of the chain. It can often start and stop right there and influence the whole system.

 

This positive affect that good preamplifiers can impart, is not limited to valve preamps like the Supratek. Many of the world’s most expensive sound systems inevitably have an active preamp at the helm, so I think plenty of experienced people have heard what they can do.

 

Steve.

Edited by Steve M

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38 minutes ago, Ittaku said:

It could well be that we need to add just the right kind of distortion to the sound of a recording to make it sound more real by the time it's coming out of a loudspeaker.

 

Either way, if you have the time, budget, and opportunity, audition a good preamp and see for yourself. It's very hard to go back to not using one.

Thanks god for valves😀

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Posted (edited)
52 minutes ago, Ittaku said:

For decades I was pursuing as "neutral as possible" thinking I was doing the best thing I possibly could for audio reproduction. It took me a long time to accept that this was actually bogus and that no recording is a perfect facsimile of the original sound and that hi-fi has to do as good a job as possible of trying to reproduce the original experience but that "perfectly neutral" was, in fact, impossible. Given the magnitude of distortion from speakers and the limitations of the actual room you're listening in, the job of amplification is to try and recreate that original performance within the confines of what reproducing sound in a flawed environment requires. The best amplifier manufacturers in the world concede they all add distortion to the original information - but they're trying to make it so the distortion that is added actually improves the experience rather than worsens it. No one is aiming for 0% distortion any more as that leads to horrible sounding hi-fi (ever wonder why?) That's not to say they're trying to set distortion levels high; only to make it beneficial instead of detrimental. To that end, I find that whatever it is that preamps are doing in the signal path - and it's likely to be a combination of being very robust at providing an unwavering signal into the power amplifier AND a certain amount of harmonious distortion - when done well it sounds better than without. It could well be that we need to add just the right kind of distortion to the sound of a recording to make it sound more real by the time it's coming out of a loudspeaker.

 

Either way, if you have the time, budget, and opportunity, audition a good preamp and see for yourself. It's very hard to go back to not using one.

 

Actually, Con’s second explanation of what an active preamp might be doing for him, is a good one.

 

Steve.

Edited by Steve M

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42 minutes ago, stereo coffee said:

Choosing the right power amp and likewise speakers particularly observing sensitivity and resistance loading, can solve many

problems that relate to whether a preamp is needed at all. 

 

Ideally you want to hear the source component and what it is capable of, and not to have to re- amplify the source,

Sadly there is yet to be any amplifier that fully preserves what your  source component already provides.So re amplifying it,

is not going to make it any better.   

 

If we look at efficiency of audio systems owners of Klipsh horn loaded speakers, have already nearly solved the need of unnecessary amplification, by using very efficient speakers. Their systems benefit from the amplifier not being strained

at all, most horn loaded speakers only need 20 watts to drive to very high sound pressure levels. Most power amps

offer outstanding figures of low distortion when driving just 20 watts. In other systems though with inefficient

speakers, amplifiers are strained to deliver the same levels and invariably start adding unneeded distortion. 

 

So with this in mind the wrong approach would be to purchase a power amp with 3.5 volts sensitivity for full output and have

resistance loading of 10,000 ohms. with these figures the power amp requires the source component to be further amplified.

 

 

The better choice is a power amp with much better sensitivity and resistance loading,  meaning you now have enough sensitivity

already in the  power amp exactly where it is needed. 

 

You then will find the freedom to just attenuate the audio signal as a volume control relieving the need for pre amplification. 

Today's modern components, like dedicated phono stages, and DAC's and CD players offer outstanding specification, to make

attenuation your best choice to connect with the source.

 

 

Anyone in Perth got one of these Stereo Coffee LDR passive preamps for me to hear? Really keen to audition one ...been lurking at the side about these and I should just build one, they’re cheap enough.

 

Steve.

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Posted (edited)
21 minutes ago, Steve M said:

I don’t agree with Ittaku/Con that preamps necessarily introduce coloration. This is an assumption rather than fact. With my own Supratek Cortese valve preamp (the latest circuit), it brings greater accuracy to the situation. Why do I say that it is more accurate, it’s because I can hear more fine details in the recording, better timing in the music, a real sense of the venue and a bigger soundstage. How can all of this be put down to coloration or distortion - when you are actually hearing more detail and music as the musicians originally 

I the apcence of facts we have do deal with assumptions. (Unless one believes that measurements translate accurate into what we actually here. That would be factual)

What you are describing as accurate is to me the pleasure of listening to a well engineered  recording. Live events to me sound not very detailed due to the acoustics of a given venue and or amplification and speakers involved.

That might just be me though.

 

ops, getting late. Still have to do the dishes. And then go and practice my music.

Edited by Ihearmusic

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2 minutes ago, Steve M said:

A bit like Groundhog Day this question ...

 

The first thing I would ask the OP is do you have more than one source component? If so, you probably need a preamp to switch and control volume between them.

 

Secondly, it is a complete Lottery out there in terms how power amps perform on their own, when connected directly to a source component. My experience is that sometimes you can fluke it and it can sound very good that way, but more often than not a  good preamplifier will bring something extra to the party ...a sense of realism, vivacity and a forward projection to the music (as different from a flat lifeless sound that makes you think the music is contrived by electronics).

 

I don’t agree with Ittaku/Con that preamps necessarily introduce coloration. This is an assumption rather than fact. With my own Supratek Cortese valve preamp (the latest circuit), it brings greater accuracy to the situation. Why do I say that it is more accurate, it’s because I can hear more fine details in the recording, better timing in the music, a real sense of the venue and a bigger soundstage. How can all of this be put down to coloration or distortion - when you are actually hearing more detail and music as the musicians originally intended?

 

Consider also that if you choose carefully, the preamp can be a pivotal component that passes on its goodness to the rest of the chain. It can often start and stop right there and influence the whole system.

 

This positive affect that good preamplifiers can impart, is not limited to valve preamps like the Supratek. Many of the world’s most expensive sound systems inevitably have an active preamp at the helm, so I think plenty of experienced people have heard what they can do.

 

Steve.

Hi Steve

It does not have to be a lottery if purchasers of power amps look at sensitivity for full output and resistance loading, but if they don't

you then indeed can pay the price, like losing a lottery and having to buy another ticket/amp . 

 

I defer to a discussion below David Blackmer gives, within it he provides information about time resolution.

Every active preamp schematic that I have seen is a long series circuit, and I am yet to see any that offers

ability to preserve time resolution or make any effort at all to preserve time resolution. Meaning that essential

part of audio that connects us with the music, is sadly lost forever. The subjects of interpolation and

approximation arise, to begin to address  https://en.wikipedia.org/wiki/Interpolation 

 

Whereas a well designed attenuator that is matched suitably to a power amp stands a much better chance of

preserving time resolution being delivered by the source , due to that methods enormously shorter signal path.  IMO.

 

 

 

 

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On paper... but then have a listen instead of looking at just schematics and numbers.

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7 hours ago, Ittaku said:

On paper... but then have a listen instead of looking at just schematics and numbers.

Agreed ,  in my case  I am listening, measuring and studying components and their interactions, then listening again,

its quite an enjoyable process.   

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11 hours ago, Ihearmusic said:

How far it diviates from the recording is anyone's guess.

This is what measurement of an amplifier (or preamplifier) can show.

 

9 hours ago, Ihearmusic said:

Unless one believes that measurements translate accurate into what we actually here.

They really do.   However she types/number of measurements shown in hi-fi magazines, or in product manuals, are not enough to provide the full picture.

 

58 minutes ago, stereo coffee said:

Agreed ,  in my case  I am listening, measuring and studying components and their interactions, then listening again,

its quite an enjoyable process.   

What do you do to quantify the effects of a shorter signal path?    It is thought to be totally irrelevant to audio Hz.

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Thanks for the replies. Amongst the controversy perhaps the message that i read is that if its not a good pre amp, then perhaps I am better off with no pre amp.

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4 minutes ago, JD1 said:

Thanks for the replies. Amongst the controversy perhaps the message that i read is that if its not a good pre amp, then perhaps I am better off with no pre amp.

That might be poor logic.

 

Let's say that you have some sort of matching problem between your source an power amp.   Either, impedance, gain are bad matches, or your power amp is hard to drive, or your source is poor.

 

Let's say that your preamplifier is "not a good preamp" (not terrible, but not great).   You remove it from your system.   The performance gets worse (due to above problem).    .... but it would be a mistake based on this, to think that preamps (even average ones) are always essential performing improving boxes.

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