Technical question - removing the preamp

I have read about some who have removed the pre between their dac and power amp. I understand that the NDS doesn’t have a variable output so what would happen if I removed the pre between my NDS /300 DR/ sopra 1? Is there a formula to calculate the resulting loudness? 

 

 

 

Original Post

The NDS has a rated output of 2.1V, meaning that is the maximum (the actual output will depend on the recording level and of course the music).

The 300 has a gain of 29 dB. 6dB is a doubling of voltage, so every 6dB doubles the 2.1V. 29 is nearly 5 doublings of 2.1V , so somewhere round about 60V.

Sopra 1 has a rated sensitivity of 89dB/2.83V at 1m (89dB/W into 8Ω). Every doubling of voltage gives an extra 6dB output, so 60V = ~4.3 doublings = ~4.3x6 +89  ~116dB at 1m

A second speaker playing precisely the same signal in phase adds 3dB. Doubling the distance from the speakers subtracts 6dB. So at 2m from the speakers, approx 116+3-6 =113dB. At 4m from the speakers it is 107dB.

The 300 has a transient capacity of 500VA. With 8Ω speakers 60V is nominally 450VA, so within its capability (though its continuous signal max is 90W, which is a fifth of this), however I am unclear as to how long the Supra 1 can sustain this sort of power input.

 

So, NDS feeding your 300 direct with no preamp into Supra 1s, listening at about 3m distance is likely to yield a sound level of up to about 110 dB on peaks. That is is very loud, but music with peaks up to that level could sound realistic with some programme material - though likely to be damaging to hearing with prolonged listening at that level, depending on what is the average level. (However, something with peaks at a very high levelcompared to the rest of the music - e.g. the 24bit Telarc recording of Tchaikovski’s 1812 overture - limit the maximum to 110dB may make the rest of the piece sound quiet.)

 

N.B. Many approximations in the above, but very much in that ball park.

A preamp (other than a passive one) on max is likely to be louder as the preamp adds its own gain, most being above unity.

TOBYJUG posted:

Most situations without a pre amp proper have everything that a pre amp does within a chip inside something digital - so never good news - unless it's an entirely passive staged device.

Well, it has somewhat less than a preamp does, as it has a lot less circuitry, and doesn’t have surplus  gain that a separate active preamp often adds.

Further to my calcs above, a DAC like Chord Dave, which has a volume adjustable output so can go down to zero, has a maximum output of 8V IIRC. In the above scenario that would theoretically add 12dB to the sound level. However at close to 4x the voltage of the 2.1V signal, the amp would need to deliver close to 1800VA, which is way over its capability and would be likely to be driven into clipping that could damage the speakers as well as sounding bad (and deafening the listener unless the room is huge), unless the amp shuts down or otherwise reduces the signal. In practice with that amp and those speakers it would be unlikely/unwise to turn Dave up much higher than the 2.1V of the NDS.

You kind of lost me there IB...are you saying using an NDS as a source into a Dave,then from Dave directly into the 300 would not work so well?The reason I ask,I had the Hugo 2 for about a month demo,and found it worked best using my Core as source into the H2,then directly into my non Naim amp(Anthem).I did not try it with my 250DR,because I did not have the proper cable,so maybe this setup works better with non Naim amps?I am going to ask my dealer soon,if I can borrow his Dave,to try directly into my Anthem,to see if this is really what I want.

It can also sound awful or simply uninvolving. Assuming you do have a source with variable output (the NDS doesn't), the preamp is not simply gain control. 

In the case of the Naim preamps, they are matched to trim the signal and frequency range within the operating limits of Naim power amps. Older Naim poweramps could even be damaged by using with non naim preamps. The same is still true but confined to edge cases luckily.

There are definately those on the forum who have dumped the pre entirely and happen to have been lucky and got good results by their own account. But it is pretty unusual. The pre also accounts for a lot of the Naim character. Yes it seems counterintuitive on the surface to get better sound with a longer signal path but it is a simplistic view. Each stage in the amplification chain performs its function based on the parameters of the signal fed to it from each previous stage. Each stage will have ranges of parameters within which it can operate more effectively than others. Go outside of those and it may work but suboptimally and the result could be anything from loss of resolution, dynamic range, lower SN ratio.  If the properties of the signal are extremely unfavorable, damage to the power amp.

That means it is not wrong at all to use a non Naim preamp and not wrong to drop the preamp altogether (assuming the source must have gain control), but it is a gamble and the odds are increasingly not in your favour on the latter.

Innocent Bystander posted:

Further to my calcs above, a DAC like Chord Dave, which has a volume adjustable output so can go down to zero, has a maximum output of 8V IIRC. In the above scenario that would theoretically add 12dB to the sound level. However at close to 4x the voltage of the 2.1V signal, the amp would need to deliver close to 1800VA, which is way over its capability and would be likely to be driven into clipping that could damage the speakers as well as sounding bad (and deafening the listener unless the room is huge), unless the amp shuts down or otherwise reduces the signal. In practice with that amp and those speakers it would be unlikely/unwise to turn Dave up much higher than the 2.1V of the NDS.

IB, thanks very much for the detailed reply, this is the kind of easy to use model and explainations I was looking for but couldn't find.

No quarter posted:

You kind of lost me there IB...are you saying using an NDS as a source into a Dave,then from Dave directly into the 300 would not work so well?The reason I ask,I had the Hugo 2 for about a month demo,and found it worked best using my Core as source into the H2,then directly into my non Naim amp(Anthem).I did not try it with my 250DR,because I did not have the proper cable,so maybe this setup works better with non Naim amps?I am going to ask my dealer soon,if I can borrow his Dave,to try directly into my Anthem,to see if this is really what I want.

No - sorry if unclear. This is simply for anyone using Dave (fed by a suitable renderer - which could be Core’s SPDIF output) instead of NDS

feeling_zen posted:

It can also sound awful or simply uninvolving. Assuming you do have a source with variable output (the NDS doesn't), the preamp is not simply gain control. 

In the case of the Naim preamps, they are matched to trim the signal and frequency range within the operating limits of Naim power amps. Older Naim poweramps could even be damaged by using with non naim preamps. The same is still true but confined to edge cases luckily.

There are definately those on the forum who have dumped the pre entirely and happen to have been lucky and got good results by their own account. But it is pretty unusual. The pre also accounts for a lot of the Naim character. Yes it seems counterintuitive on the surface to get better sound with a longer signal path but it is a simplistic view. Each stage in the amplification chain performs its function based on the parameters of the signal fed to it from each previous stage. Each stage will have ranges of parameters within which it can operate more effectively than others. Go outside of those and it may work but suboptimally and the result could be anything from loss of resolution, dynamic range, lower SN ratio.  If the properties of the signal are extremely unfavorable, damage to the power amp.

That means it is not wrong at all to use a non Naim preamp and not wrong to drop the preamp altogether (assuming the source must have gain control), but it is a gamble and the odds are increasingly not in your favour on the latter.

Some DACs with volume controls - Dave is one, and IIRC also Hugo and TT - have appropriate HF removal filtering, and output impedance and source capability that is quite happy and  stable into power amps even with the relatively low 18kΩ impedance of Naim NAPs.

But indeed, whether individuals like the sound direct as opposed to through a preamp is personal, and it is oft said that the Naim NACs are responsible for the Naim sound - even when fed from a non-Naim DAC, presumable modifying the signal in some discernible way - so if that is what you crave then of course the preamp may be critical.

Innocent Bystander posted:
 

 

......... So at 2m from the speakers, approx 116+3-6 =113dB. At 4m from the speakers it is 107dB.

The 300 has a transient capacity of 500VA. With 8Ω speakers 60V is nominally 450VA, so within its capability (though its continuous signal max is 90W, which is a fifth of this), however I am unclear as to how long the Supra 1 can sustain this sort of power input.

 - - -.

I should have clarified re continuous 90W vs peak 450W:

Every doubling in amp power (i.e watts into the rated impedance, in this case 4Ω) adds 3dB , so 1/4 of the power (113W) is 6dB down, and 90W will be about 7dB down.

That means based on specs the 300 could sustain an average output of up to around 103dB at  3m listening distance, with peaks up to 110dB, and if the recording into the directly feeding NDS is one with limited dynamic range recorded at maximum average level this could be a feasible result. 

An average level of 103 dB is very loud indeed, and sustained for more than a few minutes is definitely into hearing damage territory! 

Innocent Bystander posted:
<snip>

But indeed, whether individuals like the sound direct as opposed to through a preamp is personal, and it is oft said that the Naim NACs are responsible for the Naim sound - even when fed from a non-Naim DAC, presumable modifying the signal in some discernible way - so if that is what you crave then of course the preamp may be critical.

ALL amps modify the signal in some way or other (none are the mythical "just a straight wire with gain").

Naim use the sound modifications created by the preamp to (partially) offset the sound modifications that will occur in their power amps (as do a lot of amp designers).

A different sound modification!

I've deigned using passive preamps, and you have to alter the power amp circuit to accommodate them properly  If you don't modify them for this use, there's often more modification to the sound at the interface between the passive pre and the power amp input than usually occurs in a well designed active preamp.

Innocent Bystander posted:

The NDS has a rated output of 2.1V, meaning that is the maximum (the actual output will depend on the recording level and of course the music).

The 300 has a gain of 29 dB. 6dB is a doubling of voltage, so every 6dB doubles the 2.1V. 29 is nearly 5 doublings of 2.1V , so somewhere round about 60V.

Sopra 1 has a rated sensitivity of 89dB/2.83V at 1m (89dB/W into 8Ω). Every doubling of voltage gives an extra 6dB output, so 60V = ~4.3 doublings = ~4.3x6 +89  ~116dB at 1m

A second speaker playing precisely the same signal in phase adds 3dB. Doubling the distance from the speakers subtracts 6dB. So at 2m from the speakers, approx 116+3-6 =113dB. At 4m from the speakers it is 107dB.

The 300 has a transient capacity of 500VA. With 8Ω speakers 60V is nominally 450VA, so within its capability (though its continuous signal max is 90W, which is a fifth of this), however I am unclear as to how long the Supra 1 can sustain this sort of power input.

 

So, NDS feeding your 300 direct with no preamp into Supra 1s, listening at about 3m distance is likely to yield a sound level of up to about 110 dB on peaks. That is is very loud, but music with peaks up to that level could sound realistic with some programme material - though likely to be damaging to hearing with prolonged listening at that level, depending on what is the average level. (However, something with peaks at a very high levelcompared to the rest of the music - e.g. the 24bit Telarc recording of Tchaikovski’s 1812 overture - limit the maximum to 110dB may make the rest of the piece sound quiet.)

 

N.B. Many approximations in the above, but very much in that ball park.

A preamp (other than a passive one) on max is likely to be louder as the preamp adds its own gain, most being above unity.

Excellent answer.

Innocent Bystander posted:

Some DACs with volume controls - Dave is one, and IIRC also Hugo and TT - have appropriate HF removal filtering, and output impedance and source capability that is quite happy and  stable into power amps even with the relatively low 18kΩ impedance of Naim NAPs.

But indeed, whether individuals like the sound direct as opposed to through a preamp is personal, and it is oft said that the Naim NACs are responsible for the Naim sound - even when fed from a non-Naim DAC, presumable modifying the signal in some discernible way - so if that is what you crave then of course the preamp may be critical.

I tried to drive my 250 and a another (tube) amplifier directly from the Chord Hugo and in both cases I found the sound tiring after a few minutes. IB, do you think that those who prefer using a preamplifier between a dac and the amplifier happen to like coloration and the higher you go into the preamplifier hierarchy, the more sophisticated the colouration? 

Huge posted:

A different sound modification!

I've deigned using passive preamps, and you have to alter the power amp circuit to accommodate them properly  If you don't modify them for this use, there's often more modification to the sound at the interface between the passive pre and the power amp input than usually occurs in a well designed active preamp.

Some manufacturers go to great lengths to try to minimise any character imposed by their power amps, and try to minimise the effects of interaction wth sources and loads etc.  though of course the less than perfect real world all is a balance of the various compromises - but to what it extent that may be evident to a listener can be very variable, and a preamp can’t correct for every imperfection in a power amp, while of course it is itself a balance of different design challenges.

In other words, the only way to tell what you prefer is to hear!

Innocent Bystander posted:
Huge posted:

A different sound modification!

I've deigned using passive preamps, and you have to alter the power amp circuit to accommodate them properly  If you don't modify them for this use, there's often more modification to the sound at the interface between the passive pre and the power amp input than usually occurs in a well designed active preamp.

Some manufacturers go to great lengths to try to minimise any character imposed by their power amps, and try to minimise the effects of interaction wth sources and loads etc.  though of course the less than perfect real world all is a balance of the various compromises - but to what it extent that may be evident to a listener can be very variable, and a preamp can’t correct for every imperfection in a power amp, while of course it is itself a balance of different design challenges.

In other words, the only way to tell what you prefer is to hear!

Exactly (hence the "partially" comment in my previous reply).  As a general rule the more an amp costs the more it will have been tuned to give an even handed performance that minimises additions (e.g. colourations) and losses (e.g. reduced 'definition'); but different manufacturers balance these (and the many different colourations) differently - hence the 'house sound' from many manufacturers.

As you rightly point out "the only way to tell what you prefer is to hear!".
          - It's always an engineering compromise, no amp is the mythical "just a straight wire with gain", and all the components and cables in a system interact to some degree or other!

cat345 posted:
Innocent Bystander posted:

Some DACs with volume controls - Dave is one, and IIRC also Hugo and TT - have appropriate HF removal filtering, and output impedance and source capability that is quite happy and  stable into power amps even with the relatively low 18kΩ impedance of Naim NAPs.

But indeed, whether individuals like the sound direct as opposed to through a preamp is personal, and it is oft said that the Naim NACs are responsible for the Naim sound - even when fed from a non-Naim DAC, presumable modifying the signal in some discernible way - so if that is what you crave then of course the preamp may be critical.

I tried to drive my 250 and a another (tube) amplifier directly from the Chord Hugo and in both cases I found the sound tiring after a few minutes.

IB, do you think that those who prefer using a preamplifier between a dac and the amplifier happen to like coloration  very possibly yes -  though that presumes no or negligible interaction between DAC and power amp causing adverse audible effect, and that of course is likely to vary between different DACs and between different power amps.

and the higher you go into the preamplifier hierarchy, the more sophisticated the colouration? Hmm, not sure , rather the preamps should be improving up the range, so less colouration as the compromises are tackled - unless the colouration is intended, and if the latter does apply I suppose it could become more refined.

 

Innocent Bystander posted:
cat345 posted:
Innocent Bystander posted:

Some DACs with volume controls - Dave is one, and IIRC also Hugo and TT - have appropriate HF removal filtering, and output impedance and source capability that is quite happy and  stable into power amps even with the relatively low 18kΩ impedance of Naim NAPs.

But indeed, whether individuals like the sound direct as opposed to through a preamp is personal, and it is oft said that the Naim NACs are responsible for the Naim sound - even when fed from a non-Naim DAC, presumable modifying the signal in some discernible way - so if that is what you crave then of course the preamp may be critical.

I tried to drive my 250 and a another (tube) amplifier directly from the Chord Hugo and in both cases I found the sound tiring after a few minutes.

IB, do you think that those who prefer using a preamplifier between a dac and the amplifier happen to like coloration  very possibly yes -  though that presumes no or negligible interaction between DAC and power amp causing adverse audible effect, and that of course is likely to vary between different DACs and between different power amps.

and the higher you go into the preamplifier hierarchy, the more sophisticated the colouration? Hmm, not sure , rather the preamps should be improving up the range, so less colouration as the compromises are tackled - unless the colouration is intended, and if the latter does apply I suppose it could become more refined.

 

I understand your logic but Naim has always considered the preamplifier and the amplifier as one amplification device. If you remove the preamplifier from the system why bother with a Naim amp in the first place?

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

cat345 posted:

<snip>

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

I didn't know that the Hugo (any flavour) or DAVE had enough output power to drive a set of loudspeakers to any practical level!

cat345 posted: 

Somebody somewhere is not telling the truth!

The is no “truth” in this case, only opinions and different methods of achieving what the designer considers “best”.

While I don’t mean this in any way derogatory... perhaps that is the difference between HiFi and PRaT; between listening to the equipment and listening to music.

Huge posted:
cat345 posted:

<snip>

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

I didn't know that the Hugo (any flavour) or DAVE had enough output power to drive a set of loudspeakers to any practical level!

Should have mentioned for headphone use... 

So, are preamplifiers only good for source switching or what? 

Eloise posted:
cat345 posted:

So, are preamplifiers only good for source switching or what? 

No, that’s why passive preamps are not favoured in Naim systems...

Active pre amplifiers also

1 Act a buffer amplifiers preventing the load and any back emf presented by the power amp form affecting the output of the source component.

2 Can be used to tailor the end-to-end signal of the pre-amp / power-amp pair to an acoustically more neutral rendering than is given by the power-amp alone.

3  Increase the power of the signal available thus relieving the power-amp of part of it's amplification duties.

4 Allow lower gain power-amps to be used that then have inherently higher noise immunity (particularly in terms of PSRR).

There are plenty of people running speakers directly off the Dave,with NO amp,just the 2 Watts that the DAC outputs.Google Omega Super Alinco moniters,they are high efficiency single driver speakers.The Dave allows you to run one or two powered subwoofers at the same time.

audio1946 posted:

a well designed passive is just has good , volume pot, has to be sell designed  .number of inputs may be an issue  

Yes, sometimes, but the power-amp HAS to be specifically designed to be driven via a passive controller for it to work to the best that the power-amp can deliver.

Huge posted:
Eloise posted:
cat345 posted:

So, are preamplifiers only good for source switching or what? 

No, that’s why passive preamps are not favoured in Naim systems...

Active pre amplifiers also

1 Act a buffer amplifiers preventing the load and any back emf presented by the power amp form affecting the output of the source component.

2 Can be used to tailor the end-to-end signal of the pre-amp / power-amp pair to an acoustically more neutral rendering than is given by the power-amp alone.

3  Increase the power of the signal available thus relieving the power-amp of part of it's amplification duties.

4 Allow lower gain power-amps to be used that then have inherently higher noise immunity (particularly in terms of PSRR).

That partly satisfy my objective worries and explain my subjective ascertainment!

cat345 posted:
Innocent Bystander posted:
cat345 posted:
Innocent Bystander posted:

Some DACs with volume controls - Dave is one, and IIRC also Hugo and TT - have appropriate HF removal filtering, and output impedance and source capability that is quite happy and  stable into power amps even with the relatively low 18kΩ impedance of Naim NAPs.

But indeed, whether individuals like the sound direct as opposed to through a preamp is personal, and it is oft said that the Naim NACs are responsible for the Naim sound - even when fed from a non-Naim DAC, presumable modifying the signal in some discernible way - so if that is what you crave then of course the preamp may be critical.

I tried to drive my 250 and a another (tube) amplifier directly from the Chord Hugo and in both cases I found the sound tiring after a few minutes.

IB, do you think that those who prefer using a preamplifier between a dac and the amplifier happen to like coloration  very possibly yes -  though that presumes no or negligible interaction between DAC and power amp causing adverse audible effect, and that of course is likely to vary between different DACs and between different power amps.

and the higher you go into the preamplifier hierarchy, the more sophisticated the colouration? Hmm, not sure , rather the preamps should be improving up the range, so less colouration as the compromises are tackled - unless the colouration is intended, and if the latter does apply I suppose it could become more refined.

 

I understand your logic but Naim has always considered the preamplifier and the amplifier as one amplification device. If you remove the preamplifier from the system why bother with a Naim amp in the first place?

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

Both are telling the truth.

If you use a Naim amplifier, follow Naim's advice.

If you use a Chord  amplifier, refer to Chord advice.

 

cat345 posted:

 

I understand your logic but Naim has always considered the preamplifier and the amplifier as one amplification device. If you remove the preamplifier from the system why bother with a Naim amp in the first place?

 

My understanding is that, unlike other manufacturers’ products, the Naim power amps do not use banks of parallel pairs of output transistors, claiming the parallell approach inevitably has an adverse effect. That to me would be a good reason to listen to one.

cat345 posted:

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

A preamp used with Dave would alllow selection of analog source or sources, a d often have additional line-level outputs useful for recording, or feeding to another room etc. Until Davina (Chord’s planned ADC) is available which might replace the need, a preamp is pretty much indispensible if you have analog sources.

analogmusic posted 

I understand your logic but Naim has always considered the preamplifier and the amplifier as one amplification device. If you remove the preamplifier from the system why bother with a Naim amp in the first place?

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

Both are telling the truth.

If you use a Naim amplifier, follow Naim's advice.

If you use a Chord  amplifier, refer to Chord advice.

 

It's not a matter of having to believe one advice over the other, I just want to understand why so I can make my own idea.

This preamplifier thing seem to be a taboo subject since the arrival of dacs having a volume control.

cat345 posted:
analogmusic posted 

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers? 

 

I think you'll find Rob Watts, Nam and most other amplifier designers all agree with each other - as it fairly standard practice. The point about Chord Electronics is that they produce preamp stages in their DAC outputs such that they present a fixed impedance irrespective of attenuation. Naim typically provide this function in the NAC

Innocent Bystander posted:
cat345 posted:

 

I understand your logic but Naim has always considered the preamplifier and the amplifier as one amplification device. If you remove the preamplifier from the system why bother with a Naim amp in the first place?

 

My understanding is that, unlike other manufacturers’ products, the Naim power amps do not use banks of parallel pairs of output transistors, claiming the parallell approach inevitably has an adverse effect. That to me would be a good reason to listen to one.

cat345 posted:

Chord's dac engineer Rob Watts advise not to use any amplification devices after the dac output for maximum fidelity. If that should be believed, why is Chord still selling mega buck preamplifiers?

Somebody somewhere is not telling the truth!

A preamp used with Dave would alllow selection of analog source or sources, a d often have additional line-level outputs useful for recording, or feeding to another room etc. Until Davina (Chord’s planned ADC) is available which might replace the need, a preamp is pretty much indispensible if you have analog sources.

I hope this ADC/DAC thing does not become the only standard of the industry. I just want to enjoy my AAA records forever! 

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