BTW - does anyone know of where to get those PCB mount RCA connectors that audiofreak talks of in the UK? i Have tried RS and arrow. You know the ones with a plasic mounding to PCB mount them and the screw hole to attach it to perpendicular case work, so you can easily put on 16 RCA's in one go?
Nania,
If you are driving a speaker with a sensitivity of 80db/W/m with an amp putting out 0.5W, the speaker will be putting out 77db SPL at 1m. If your ambient noise is 55db then the dynamic range of your system will be 22db. This is about the dynamic range you can expect from a mediocre LP pressing. From a good LP, you should be able to get over 40db of dynamic range and more then that is possible from a CD. The problem starts to be on the recording studio side where everything has to be perfect to get 50 or 60db of dynamic range into a recording.
But let's go with the 40db dynamic range. If you start from your ambient of 55db, you will need to generate 95db to reproduce the full dynamics of the music. Thats 18db more then your 0.5W amp has to give (or double 0.5W, 6 times). That means you need a 32W amp to just make the 40db of dynamic range. To make 50db of dynamic range, you would need a 300W amplifier. To get to 60db, you'll have to make your home much quieter.
Hope this is what your looking for.
Rodd Yamashita
If you are driving a speaker with a sensitivity of 80db/W/m with an amp putting out 0.5W, the speaker will be putting out 77db SPL at 1m. If your ambient noise is 55db then the dynamic range of your system will be 22db. This is about the dynamic range you can expect from a mediocre LP pressing. From a good LP, you should be able to get over 40db of dynamic range and more then that is possible from a CD. The problem starts to be on the recording studio side where everything has to be perfect to get 50 or 60db of dynamic range into a recording.
But let's go with the 40db dynamic range. If you start from your ambient of 55db, you will need to generate 95db to reproduce the full dynamics of the music. Thats 18db more then your 0.5W amp has to give (or double 0.5W, 6 times). That means you need a 32W amp to just make the 40db of dynamic range. To make 50db of dynamic range, you would need a 300W amplifier. To get to 60db, you'll have to make your home much quieter.
Hope this is what your looking for.
Rodd Yamashita
Roddyama
AudioFreak
Where did you get this number from? I believe I read somewhere that the maximum dynamic range that can be recorded is 20dB and that 80% of music never exceeds 6dB dynamic intervals.
AudioFreak
Thanks for clearing that up. So the notion of peak dynamic output is a fiction, can I get everyone to agree on this? Then what is meant by audio reviewers when they speak of dynamic reserve? I know that this a game of semantics but words are all we have to describe what we know. The only other way is to watch someone as they do it and mimic.
For pure Single Ended Class A designs Dynamic Headroom is Zero because they cannot exceed the bias point. On the other hand, Dynamic Headroom / Dynamic Reserve are valid terms in Class AB/B/G designs because they are designed to deliver current in excess of the Bias point but as has been demonstrated in this thread most manufactures dont make good use of it except to allow PR to cover the pitfalls of the design.
AudioFreak
Okay, we're rounding third and coming for home now. An amp operating in Class A cannot by definition have peak dynamics because both the positive and negative sides of the signal are in constant amplification, correct? The peak Mr. Pass refers to is the peak power output only related to its sinusoidal nature in Class A operation, correct? Since the amplification is continuous , there is no need for stop/start peak demands, am I still on track? If I got the above, all that is left unanswered is the question of the dynamic requirements of recorded music. Is it possible for a recording to posess the ability to exceed a 20dB dynamic swing?
Nania,
The jacket for the Telarc version of Stravinsky's Firebird has a technical discussion on digital recordings and cutting it to vinyl. It states the real dynamic range (softest sound to loudest sound) of a symphony orchestra is 80db! The Soundstream system used to make the master recordings can record a 90db dynamic range. These digital recordings and high quality amplifiers are used to drive the cutter heads that make the master records. These records will easily exceed 40db of dynamic range. One way to see this is the VU bar meters on my Nakamichi cassette recorder. The full dynamics of the record are almost unrecordable. The meter will span from -40 to +10.
Certianly these are the extremes, but they are also 20 years old. CD's are very capable of 60db of dynamic range. If you limit your system to 20db of dynamic range, it will be continually clipping the amp. on and average CD.
Rodd Yamashita
The jacket for the Telarc version of Stravinsky's Firebird has a technical discussion on digital recordings and cutting it to vinyl. It states the real dynamic range (softest sound to loudest sound) of a symphony orchestra is 80db! The Soundstream system used to make the master recordings can record a 90db dynamic range. These digital recordings and high quality amplifiers are used to drive the cutter heads that make the master records. These records will easily exceed 40db of dynamic range. One way to see this is the VU bar meters on my Nakamichi cassette recorder. The full dynamics of the record are almost unrecordable. The meter will span from -40 to +10.
Certianly these are the extremes, but they are also 20 years old. CD's are very capable of 60db of dynamic range. If you limit your system to 20db of dynamic range, it will be continually clipping the amp. on and average CD.
Rodd Yamashita
CORRECT!!!
I would try to allow at least 40dB of dynamic range (that is the difference between the the quietest and lowest passage the system is able to deliver cleanly) in the system... assuming 55dB ambient noise, that is 95dB now assuming 85dB/w @ 1m speakers, 10W RMS per channel is enough which means the amplifier is delivering 20W instantaneous power on the very peaks of the largest sine waves just before clipping.
If you want 60dB dynamic range then it's time to start using various room treatments and very efficienct speakers. If you got ambient noise down to 50dB then peaks would be 110dB. To achieve that you really need speakers that are 95dB/w @ 1m or higher... Assuming 100dB/w @ 1m speakers that still requires the same 10W RMS per channel amps.
Now all of the above assumes you are only 1m from the speakers... things get worse very quickly the further away from the speakers you are.
I would try to allow at least 40dB of dynamic range (that is the difference between the the quietest and lowest passage the system is able to deliver cleanly) in the system... assuming 55dB ambient noise, that is 95dB now assuming 85dB/w @ 1m speakers, 10W RMS per channel is enough which means the amplifier is delivering 20W instantaneous power on the very peaks of the largest sine waves just before clipping.
If you want 60dB dynamic range then it's time to start using various room treatments and very efficienct speakers. If you got ambient noise down to 50dB then peaks would be 110dB. To achieve that you really need speakers that are 95dB/w @ 1m or higher... Assuming 100dB/w @ 1m speakers that still requires the same 10W RMS per channel amps.
Now all of the above assumes you are only 1m from the speakers... things get worse very quickly the further away from the speakers you are.
Right,
You get a little help (3db) from stereo speakers, that is if they're both playing the same sounds (mostly in the bass), but the SPL drops 6db for every doubling of the distance.
I set my goal 25 years ago at +60db dynamic range so I had to go with horns. I'm a bit fanatical about dynamics. To me it's what brings the music to life. I went to reproduce 1 acoustic Watt which is about 115db in the average sized livingroom (in the US). That way it was always easy to know what size amp I needed by the efficiency of the speakers.
Rodd Yamashita
Dynamic headroom etc
Huh? The class of the amp has nothing to do with dynamic headroom (which incidently, is not a NAD invention. Stereo Review used it a long time to indicate a worthwhile trait of an otherwise unpreprosessing amp).
If your amp can deliver say 20 watts RMS continuously in 8 Ohms, but can deliver short term peaks of say 1 sec of 40 watts in the same 8 Ohms, that amp has 6dB dynamic headroom. The idea is that on music, which has a very high ratio of peak to average level, the 20W, 6dB headroom amp sounds like a 40W amp, yet you pay only for 20W hardware. The headroom effect is always seen, except in amps with tightly regulated power supplies, because all power supplies sag to some extend under load.
In fact, many if not most class A amps deliver output power in excess of their class A range; they just enter a class AB region when driven hard.
Jan Didden
nania said:
Huh? The class of the amp has nothing to do with dynamic headroom (which incidently, is not a NAD invention. Stereo Review used it a long time to indicate a worthwhile trait of an otherwise unpreprosessing amp).
If your amp can deliver say 20 watts RMS continuously in 8 Ohms, but can deliver short term peaks of say 1 sec of 40 watts in the same 8 Ohms, that amp has 6dB dynamic headroom. The idea is that on music, which has a very high ratio of peak to average level, the 20W, 6dB headroom amp sounds like a 40W amp, yet you pay only for 20W hardware. The headroom effect is always seen, except in amps with tightly regulated power supplies, because all power supplies sag to some extend under load.
In fact, many if not most class A amps deliver output power in excess of their class A range; they just enter a class AB region when driven hard.
Jan Didden
Re: Dynamic headroom etc
Of course with Single Ended Class A designs, you still can only effectively get Zero Dynamic Headroom as once the bias current is reached, the amp clips and that is that. Even if you use a Aleph current source or another such trick you increase the efficiency but you still have Zero Dynamic Headroom.
With push pull designs, it is common to have some Dynamic Headroom although dependant on bias and power supply you can still have Zero Dynamic Headroom ... By definition, Dynamic Headroom is power which an amp can deliver on a non-continuous basis above and beyond that of the continuous rating. If the power supply rails are only marginally higher than that required for the peaks of the sine wave RMS rating then the amp will still have Zero Dynamic Headroom or very near to it indeed regardless of if it is a push pull design or single ended.
Furthermore, if an amp operates to 20W RMS class A then procedes to operate to 100W RMS continuously Class AB that is not Dynamic Headroom as the amp is able to deliver that power on a continual basis regardless of class... It is primarily the power supply that determines if the amp has appreciable Dynamic Headroom and to a lesser extent the output stage.
janneman said:
Of course with Single Ended Class A designs, you still can only effectively get Zero Dynamic Headroom as once the bias current is reached, the amp clips and that is that. Even if you use a Aleph current source or another such trick you increase the efficiency but you still have Zero Dynamic Headroom.
With push pull designs, it is common to have some Dynamic Headroom although dependant on bias and power supply you can still have Zero Dynamic Headroom ... By definition, Dynamic Headroom is power which an amp can deliver on a non-continuous basis above and beyond that of the continuous rating. If the power supply rails are only marginally higher than that required for the peaks of the sine wave RMS rating then the amp will still have Zero Dynamic Headroom or very near to it indeed regardless of if it is a push pull design or single ended.
Furthermore, if an amp operates to 20W RMS class A then procedes to operate to 100W RMS continuously Class AB that is not Dynamic Headroom as the amp is able to deliver that power on a continual basis regardless of class... It is primarily the power supply that determines if the amp has appreciable Dynamic Headroom and to a lesser extent the output stage.
Re: Re: Dynamic headroom etc
I agree with most of your post, and you are right about the zero headroom on SE amps. But do we agree that in case of PP designs normally (nonregulated) supplies are higher than required for the sine wave RMS rating, especially under normal music reproduction conditions. Then the amp will always have *some* non-zero dynamic headroom. The question is, do we regard it as an unfortunate shortcoming, or do we exploit it as a usefull way to improve the transient power available. Going back to the origin of this post, my view is that NAD tried to exploit it, and rightly so.
Cheers, Jan Didden
AudioFreak said:
I agree with most of your post, and you are right about the zero headroom on SE amps. But do we agree that in case of PP designs normally (nonregulated) supplies are higher than required for the sine wave RMS rating, especially under normal music reproduction conditions. Then the amp will always have *some* non-zero dynamic headroom. The question is, do we regard it as an unfortunate shortcoming, or do we exploit it as a usefull way to improve the transient power available. Going back to the origin of this post, my view is that NAD tried to exploit it, and rightly so.
Cheers, Jan Didden
"If your amp can deliver say 20 watts RMS continuously in 8 Ohms, but can deliver short term peaks of say 1 sec of 40 watts in the same 8 Ohms, that amp has 6dB dynamic headroom. The idea is that on music, which has a very high ratio of peak to average level, the 20W, 6dB headroom amp sounds like a 40W amp, yet you pay only for 20W hardware. The headroom effect is always seen, "
A 2:1 power ratio is only 3dB, 4:1 is 6dB. And yes, headroom is always seen, but not for 1 sec like the NAD delivers. Most designs have 3dB of headroom, but only for a few mSec. Remember, a 1F cap can deliver 1A for 1Sec. The NAD power envelope design is truely a different breed.
As far as dynamic range in recordings go, Tricycle (on DMP) is a favorite of mine. With a fresh victim I set the amplifier gain 3dB into clipping and cue it up. Starts out with a solo piano. You know you are in trouble when you realize you can hear the hiss from the noise floor of the digital recorder. Then the drums and bass come in at 0dB. 80+ dB of dynamic range. Many victims leap to their feet when the bass hits. Be careful, the bass player has an octave divider too!
A 2:1 power ratio is only 3dB, 4:1 is 6dB. And yes, headroom is always seen, but not for 1 sec like the NAD delivers. Most designs have 3dB of headroom, but only for a few mSec. Remember, a 1F cap can deliver 1A for 1Sec. The NAD power envelope design is truely a different breed.
As far as dynamic range in recordings go, Tricycle (on DMP) is a favorite of mine. With a fresh victim I set the amplifier gain 3dB into clipping and cue it up. Starts out with a solo piano. You know you are in trouble when you realize you can hear the hiss from the noise floor of the digital recorder. Then the drums and bass come in at 0dB. 80+ dB of dynamic range. Many victims leap to their feet when the bass hits. Be careful, the bass player has an octave divider too!
Common Grounds
Given that the vast majority of Class AB amps have tiny power supplies and therefore have little choice but to sag, they almost universally have higher voltage rails then is required for the RMS output and therefore will indeed have some Dynamic Headroom.
It appears NAD uses a slightly alternate topology to the standard class AB however the principles are the same except that it appears they have one decently rated lower voltage rail and an under-rated high voltage rail ... kind of a mix between class ab and class g from what i can tell. In the end it comes down to the fact that they have tried to provide a bit of extra short-term kick without the price premium. I believe it is up to the individual to determine if this amp is a sound investment and therefore in their sight well engineered.
Given that the vast majority of Class AB amps have tiny power supplies and therefore have little choice but to sag, they almost universally have higher voltage rails then is required for the RMS output and therefore will indeed have some Dynamic Headroom.
It appears NAD uses a slightly alternate topology to the standard class AB however the principles are the same except that it appears they have one decently rated lower voltage rail and an under-rated high voltage rail ... kind of a mix between class ab and class g from what i can tell. In the end it comes down to the fact that they have tried to provide a bit of extra short-term kick without the price premium. I believe it is up to the individual to determine if this amp is a sound investment and therefore in their sight well engineered.
Roddyama
This seems to conflict with your earlier statement:
How is going from 80dB to 77dB "help"?
I know that live concerts of some pieces will have 90dB dynamics when you are there live but not on a recording! I don't think there is a mixer (mastering board) that can provide better than 30dB and only 2/3 of that is usable because of crosstalk problems in handling the dynamics and the compression needed to lower the noise floor. If you look at sales literature of mixers, going from 20dB to 21dB is a big deal so I suspect the numbers you have provided are not accurate. I believe you are putting a lot of faith in the nakamichi meter readings. Are there any sound engineers in this forum to provide a little more insight?
This seems to conflict with your earlier statement:
How is going from 80dB to 77dB "help"?
I know that live concerts of some pieces will have 90dB dynamics when you are there live but not on a recording! I don't think there is a mixer (mastering board) that can provide better than 30dB and only 2/3 of that is usable because of crosstalk problems in handling the dynamics and the compression needed to lower the noise floor. If you look at sales literature of mixers, going from 20dB to 21dB is a big deal so I suspect the numbers you have provided are not accurate. I believe you are putting a lot of faith in the nakamichi meter readings. Are there any sound engineers in this forum to provide a little more insight?
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