newlash09

To preamp or not

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Hi all 

I guess this question has been beaten to death already. And I myself have always encouraged the idea of a separate preamp, as lots of user experience in this forum seemed to have suggested audible gains. 

So I find myself in a conundrum now. I have been running power amps directly out of the AMR dac, which has a variable analogue volume control. And have been happy with the sound so far. Recently one of my friends suggested, that I should add a pre amp as it would improve the dynamics and clarity of my system. As per him, a single power supply powering both the digital dac section and analogue volume control section, would be starving the analogue volume control section off power to get great dynamics. So a dedicated preamp with its singular minded power supply will deliver better dynamics. I can probably believe this argument, as I don't know how robust the AMR's power supply is. 

But my doubt is the improvement in clarity part. Can adding an external dedicated pre amp, improve the clarity of the same AMR's output, once i bypasss the AMR's volume control and set it to fixed output. I remember lots of folks having tried this in their setups. So I am once again curious to know others experiences. Thanks 

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Super Wammer
Posted (edited)

Theory: a preamp simply can't add clarity; nothing can.

Practice: Nick @Fourlegs has a couple of highly regarded passive preamps from Music First Audio: both sound excellent to me though one is tighter in the bass. Passive pre's work on the principle that the least circuitry in the loop the better, and for this reason Transformer Volume Control (TVC) pre's are the dogs wotsits. Despite having probably the most highly regarded pre's out there (arguable of course: some folk like a pre to add something in but this something can't be clarity), Nick runs his active ATC's direct from the Chord DAC not via either of these pre's. See Theory above.

Nick will no doubt be along shortly to confirm/clarify/reject.

Edited by TheFlash
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It's more about matching gain. If you are happy then leave well alone (I am the single worst offender here, I don't follow my own advice ). It's a bit of a merry go round. If the power amp is low gain you'll need some oomph from an ACTIVE pre and benefit, but if like most it has a sensitivity of 1.4V for full output then it won't. TVCs are a red herring in this context as you have a volume control already. I personally like digital volume controls as they are more 'transparent' and less reactive in the system in my experience, others disagree.

No, under no circumstances can an extra stage add clarity

Sent from my BLA-L09 using Tapatalk

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Super Wammer

Just to throw something else into the equation I have consistently found that valve power amps do not produce their best when fed directly from DACs with built in digital volume controls. There I found that the best sound is when the dac is set to a fixed output around 2v and then a preamp is used for volume. I used a variety of actives but my favorite by a country mile were music first transformer volume control passives. I know this is a red herring but I find it interesting. 

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Super Wammer
Posted (edited)

If the volume control in the DAC is analogue as described then it is best to take max output from that into a TVC pre which attenuates as required.

Digital volume controls are not all the same, many chop bits off to attenuate (I hope that slack terminology works) so degrade the signal, but the best don't.

[EDIT: sorry, Nick, crossed in the post]

Edited by TheFlash
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Super Wammer

@newlash09  this is far too simple. You surely need six mono preamps, one for each speaker drive unit. ;-)

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5 minutes ago, Fourlegs said:

Just to throw something else into the equation I have consistently found that valve power amps do not produce their best when fed directly from DACs with built in digital volume controls. There I found that the best sound is when the dac is set to a fixed output around 2v and then a preamp is used for volume. I used a variety of actives but my favorite by a country mile were music first transformer volume control passives. I know this is a red herring but I find it interesting. 

That is an interesting observation.

A number of years ago I decided I needed a remote control to adjust the volume and so my EAR864 had to go. I decided to try a Bel Canto 3.5 vbs as it had a volume control AND an analogue input, and I was disappointed; add a Bel Canto Pre3 vbs and all was sweetness and light -- this was into my EAR534 power amp.

A few weeks ago I bought a 3 channel Nord One UP NC500. Linking this to my Oppo 105D the sound quality is excellent; as good as my Linn Klimax DS/1 renew & EAR868? No. But it is no slam dunk.

As a result of my earlier experience I would always recommend a preamp, but I had not considered the differences between a SS and valve power amp.

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I have never bothered to work out what and why it is, but I have never, ever been 100% happy with any of the variants of my system without an active pre. I ceryainly don't think it improves 'clarity', if anything the opposite. Mr scientist me should hate what I'm about to say, but I find an active pre (especially a good tube-based one) adds some 'width and depth'. No. I know it doen't make sense, but I am experiencing it at the moment. I sold my extremely capable tube pre a few weeks back and it's home-built replacement is still half finished. Running the CD as a transport through my Audiosector NOS DAC and using the passive gain on the power amp the sound is flat and comparatively lifeless.

I've rooted around in the junk pile and found one of those stupid Chinese buffer/pre things that were peanuts. Hacked it about and I'm using it as a buffer, and immediately it's substantially better. Impedance matching possibly? Quite likely I suppose, but I don't care frankly (though I should).

Basically, if you have tube power amps and a CD player, then at some stage you owe it to yourself to try a decent tube pre-amp and see what happens. To me, the answer to that has always been 'magic'.

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Thanks all for the advise :)

I guess I will go for a pre amp, as I need to run both SS and tube amps through a crossover. Iam considering going for a active pre amp, as I might need some gain, as I will be driving multiple power amps from the same pre amp. 

Tube preamps do sound like a good idea. But a quick look around has shown them to be quiet expensive once they have the required functionality,  something even like a remote volume control. So will start considering some SS preamps....will also keep a good eye out for tube preamps too. Thanks again for the suggestions :)

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17 minutes ago, rabski said:

I have never bothered to work out what and why it is, but I have never, ever been 100% happy with any of the variants of my system without an active pre. I ceryainly don't think it improves 'clarity', if anything the opposite. Mr scientist me should hate what I'm about to say, but I find an active pre (especially a good tube-based one) adds some 'width and depth'. No. I know it doen't make sense, but I am experiencing it at the moment. I sold my extremely capable tube pre a few weeks back and it's home-built replacement is still half finished. Running the CD as a transport through my Audiosector NOS DAC and using the passive gain on the power amp the sound is flat and comparatively lifeless.

I've rooted around in the junk pile and found one of those stupid Chinese buffer/pre things that were peanuts. Hacked it about and I'm using it as a buffer, and immediately it's substantially better. Impedance matching possibly? Quite likely I suppose, but I don't care frankly (though I should).

Basically, if you have tube power amps and a CD player, then at some stage you owe it to yourself to try a decent tube pre-amp and see what happens. To me, the answer to that has always been 'magic'.

What Rabski said - and I do not think it is just down to tube amps.  In my time selling stuff and playing with stuff for many years to my ears a good active preamp beats a passive hands down.  The thing is I guess in theory the Passive has to be more accurate (well less components and no gain stage to mess up the signal) but somehow to me always sounds dull and lifeless by comparison.  I totally agree with Rabski about width and depth and alive  (as opposed to lifeless).

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Moderator
Posted (edited)

You may well be right in that any active pre will work, tube or solid state.

The 'rule of thumb' is that when anything is driving anything else (CD driving pre-amp, pre-amp driving power amp, etc.), the input impedance of what's being driven should be at least 10x the output impedance of what's driving it. The vast majority of tube power amps have a comparatively very high input impedance, so almost anything ought to work fine.

Edited by rabski
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I have only experimented once.  I ran my power amp from a Wyred4Sound DAC.  It was dreadful.  Both valve (Ayon Eris) and SS (Daniel Hertz) preamps gave life and body to the presentation.

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It's all iffs and buts and seems to be very system dependent. Some systems thrive on active pre-amps, some on passive pre-amps.

My systems are in the passive pre-amp or no traditional active preamp camp.

Other systems are the opposite.

It's very much a case of giving it a try both ways. Preferably without spending any money that you can't get back in full. And seeing what you like best in your system with your ears.

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23 minutes ago, lindsayt said:

It's all iffs and buts and seems to be very system dependent. Some systems thrive on active pre-amps, some on passive pre-amps.

My systems are in the passive pre-amp or no traditional active preamp camp.

Other systems are the opposite.

It's very much a case of giving it a try both ways. Preferably without spending any money that you can't get back in full. And seeing what you like best in your system with your ears.

Very nice to see you back after a long time lindsayt :)

well noted. Iam presently leaning towards a active SS preamp. I think being active makes it future proof to a certain extent , as compared to passive, in case the system evolves further. Thanks 

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As I don't think it's been mentioned yet, I believe that your current plan would be to connect any pre-amp to your external crossover rather than directly to your power amps?

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