I've recently purchased a pair of B&W 683 speakers and a Nad C356BEE (rated 80 watts). I use a Brennan JB7 connected to the amp using a QED Reference J2P cable. My previous amp (3 days ago) was an old Denon PMA 250 iii and was rated 30 watts. My question is this: How is it that the Denon is so much louder than the Nad. The Nad is set to full volume and the Denon just over half. The Denon gets much louder than the Nad, even at this level. I prefer the Nad with the B&W's and has a better overall sound, but I was expecting a bit more power from the Nad. Who's watt measurements are correct? If I bought a 150 watt amp, who's to say it won't be the same as the Nad? Would it be good to bi-wire the two amp together, if so how do I go about this. Any help on this matter would be greatly appreciated. Thanks.
30 watts louder than 80 watts?
- Thread starter Viking
- Start date
Viking said:
We have been through this many times before........ :wall:
The setting of the volume control on an amplifier bears absolutely no resemblence to the power being delivered by the amplifier.
The way the volume control works, ie how quickly the amplifier 'gets loud', is entirely at the whim of the designer (or maybe the marketing guys).
Making an amplifier 'get loud' quickly as you increase the volume impresses the novice, the fact that such an amplifier may well be into hard clip by the time the control gets to halfway somehow seems to get missed.
Set the controls so that perceived volume of both amplifiers is the same, (measurement is better, a simple a/c millivoltmeter across the speaker terminals will suffice) and listen.
BTW What is the source you are using in this instance?
eggontoast
Well-known member
If you are setting the NAD to full volume something is up. Does the Brennan have a fixed line level output ?
BigH
Well-known member
The power ratings quoted for each are different - it's like saying 30 inches is less than 45 cm.
The Denon looks like it's the the industry standard RMS power measurment - its 30w into 8 ohms, 50 w into 4 ohms. The Nad is rated as continuous power - 80w into both 8 and 4 ohms.
Bottom line is that 80w continuous power is a lot less than 80w RMS, as you have found out. A case of manufacturer's specs being misleading I'm afraid.
edit - this doesn't negate the comments above by the way. My 60w amp sounds more powerful than the 200w one it replaced - both respected names, both using the same method for stating power
The Denon looks like it's the the industry standard RMS power measurment - its 30w into 8 ohms, 50 w into 4 ohms. The Nad is rated as continuous power - 80w into both 8 and 4 ohms.
Bottom line is that 80w continuous power is a lot less than 80w RMS, as you have found out. A case of manufacturer's specs being misleading I'm afraid.
edit - this doesn't negate the comments above by the way. My 60w amp sounds more powerful than the 200w one it replaced - both respected names, both using the same method for stating power
eggontoast
Well-known member
BigH said:
I was referring to the Denon.
Subjective loudness is difficult to assess. We do not know how loud the NAD is at full volume.
All kinds of factors come into play, input sensitivity is crucial, as is the output level of the source. The 'law' of the volume control matters, as explained above, as indeed does the distortion content, a little extra harmonic distortion makes an amplifier sound much louder.
It is worth bearing in mind that doubling the amplifier power will only lift the measured output level of the speakers by 3dB. On a music signal in a home environment that is a pretty small increase in perceived loudness, it is about the smallest change in level that can be clearly perceived as such in such situations.
No!! RMS (more accurately called continuous power handling) is the measure of how much power the speaker can endure for extended, continuous periods of use. This is an average rating since music, and thus the power required to produce it, is dynamic in nature and varies greatly from moment to moment depending on the frequency being produced and mechanical characteristics of the amplifier and speaker.
So 80 W RMS or 80 W cont power are the same
RMS or root mean squared only applies to AC voltage
So 80 W RMS or 80 W cont power are the same
RMS or root mean squared only applies to AC voltage
TrevC
Well-known member
Viking said:
You are confusing gain with power output. The rotation of the volume control tells you nothing about power output. Can you turn the wick up on the Brennan thing?
My answer is the same as it was yesterday, on your other thread:
"If you are judging the power by the position of the volume knob.....the two have no relationship to each other.
If the speakers sound better, and go loud enough for your needs, just enjoy what you have."
"If you are judging the power by the position of the volume knob.....the two have no relationship to each other.
If the speakers sound better, and go loud enough for your needs, just enjoy what you have."
RMS power is a simple definition, it is the area under the curve of the signal voltage plotted against time. In the case of a sinewave signal it is √2 times the peak voltage.
Thinking of power as the area under the curve is very helpful, a square wave for example has the maximum area possible, so RMS power is the same as peak power in this case.
You can also visualise a representation of a music signal in the same way, for well recorded music with a bit of dynamic range you will see a lot of very short duration peaks, the area under the waveform is thus quite small, so the RMS power is a tiny fraction of the peak power.
I am not aware of any similarly straightforward definition of 'continuous power'.
I had always considered it to be the power that the amplifier can deliver over a long period of time, a few seconds in this instance.
The 'real', effective power output of an amplifier is usually limited by the power supply, the output stages can usually deliver the rated power with 'fully charged' power supply capacitors but sometimes the power supply cannot keep up with demand for 'continuous power' so the output falls.
Thinking of power as the area under the curve is very helpful, a square wave for example has the maximum area possible, so RMS power is the same as peak power in this case.
You can also visualise a representation of a music signal in the same way, for well recorded music with a bit of dynamic range you will see a lot of very short duration peaks, the area under the waveform is thus quite small, so the RMS power is a tiny fraction of the peak power.
I am not aware of any similarly straightforward definition of 'continuous power'.
I had always considered it to be the power that the amplifier can deliver over a long period of time, a few seconds in this instance.
The 'real', effective power output of an amplifier is usually limited by the power supply, the output stages can usually deliver the rated power with 'fully charged' power supply capacitors but sometimes the power supply cannot keep up with demand for 'continuous power' so the output falls.
What I'd like to know is how the OP was listening to the B&W 683 'at full volume' ...
90db/2.83v m is pretty sensitive. Even 30w will result in deafening volume.
Then there's the issue of the NAD being at quote; full volume. Most amplifiers have limited travel/range on the volume control. How much? Depends on the manufacturer but I'd say anything beyond 13.00pm (1 o'clock) is close to maximum.
Now, having had Denon's myself, I can atest that they usually are very sensitive to input and even 9 on the volume is 'loud'. - They can get close to distorting at 11 on the scale.
My guess would be that the NAD's volume control is better utilised over its range, probably resulting in a better S/N ratio in the process and less distortion ie. a cleaner (perhaps seemingly quieter sound?).
I would be surprised if the little Denon with its (small) power supply is anywhere near as capable as the NAD.
Regards
90db/2.83v m is pretty sensitive. Even 30w will result in deafening volume.
Then there's the issue of the NAD being at quote; full volume. Most amplifiers have limited travel/range on the volume control. How much? Depends on the manufacturer but I'd say anything beyond 13.00pm (1 o'clock) is close to maximum.
Now, having had Denon's myself, I can atest that they usually are very sensitive to input and even 9 on the volume is 'loud'. - They can get close to distorting at 11 on the scale.
My guess would be that the NAD's volume control is better utilised over its range, probably resulting in a better S/N ratio in the process and less distortion ie. a cleaner (perhaps seemingly quieter sound?).
I would be surprised if the little Denon with its (small) power supply is anywhere near as capable as the NAD.
Regards
busb
Well-known member
eggontoast said:
But you fail to point out why - at least he is trying to be helpful. Your comment adds what exactly? RMS & continuous power should be the same if measured in the same manner as opposed to peak or instantaneous power. RMS power equates AC having the same heating effect as the equivalent DC - a pretty easy conversion with pure sine waves but more difficult with high crest factor pulses. Measuring power in the context of subjective loudness is not so straightforward - measuring a 1kHz sinewave into a resistive 8 Ohm load tells too little & can explain why some lower-spec'd amps actually deliver more watts with music being played.
eggontoast
Well-known member
busb said:
He's not being helpful though cos it's bollox.
I was intending to write more but unfortunately got interrupted mid flow, still now I don't have to as everyone else has ;-)
GCE said:
Yes, sorry RMS and continuous are the same. Should have read program (music) power is twice the RMS power handling.
PA speakers are often supplied with RMS, Program and Peak power ratings. The output of the amp should be roughly twice the RMS rating of the speaker.
Hi, the brennan has aux out, line in and 3.5mm headphone sockets. I use the headphone socket from the Brennan to rca fittings on the amp. This way it turns off the inbuilt 60 watt amp in the brennan. It was only a test I was doing to see how loud and at what stage does the Nad would distort. It was then that I noticed that I couldn't turn the Denon amp up any more due to it being too loud, but the Nad was fully turned to it's maximum. I don't really have any neighbours, so playing loud isn't a problem and the music is played in a fairly open space.
Thanks for your help.
Thanks for your help.
Here's one for the archives.
Few things one needs to consider about attenuation differences between amps.
1) Logarithmic vs Linear volume control. The first one will go louder progressively delivering into "chunks" (0.01W > 0.1W > 1W > 2.5W > 5W > 10W > 25W > 50W). Second one will go louder more quicker and more evenly spread ( 1, 2, 3, 5, 6...), sometimes giving out all the good clean watts before you reached 12 o'clock position. Logarithmic is the safe way to go since chances of accidentally blowing your speakers are slim, but it does feel emasculating to some who prefer the illusion of "9 o'clock position allready too loud, so much power."
2) Attenuation coefficient (Signal to Noise Ratio and Dynamic Peak). SNR 90db and DP 106db will go louder quicker than SNR 80db and DP 106db. Later one will sound more laidback and you will need to turn it up to get the best of it.
3) Passive attenuation vs Gained. First one just outputs 0-100% of the preamp line signal without applying gain, which leaves the gain to be applied in the power amp section (like with Exposure amps). Gain in the preamp will add db's and continue to add in the power section. The later ones I've noticed would go louder quicker, but it's not a general rule.
4) External vs Embedded Loudness curve. External is when you get to push a button to get more db in low and high frequencies at lower listening volumes. Additional loudness compensates for our hearing insensitivity to low and high frequencies for quiet listening aka Fletcher–Munson curve. Its expected for you to shut it off once you go past (usually) 8-9 o'clock, however some never do. Embedded loudness is applied by a circuit in the preamp in a way you don't get to enable/disable it. It automatically reduces from 100% to 0% added loudness once you turn the volume knob past 8-9 o'clock. Some amps have variable loudness knobs (old Yamahas) and some have no loudness compensation at all.
So basically how loud an amp gets is a function of both preamp and power amp circuitry. The preamp is tuning the little voltage (coming from your source component, cd, tape, tt, ipod) to modify the big one (coming from the wall socket) thus making weak signal go bigger - amplifiers amplify. However, similar to servo steering in cars, not all things are equal. If you go louder quicker it doesn't necessarily mean you got lots more on tap. In matter of fact it's most likely you don't and your amp will go into clipping if you crank it up even further.
Now I shared my thoughts from preamp attenuation perspective but consider there is a lot more to be said about the power section and its relation to speakers and especially crossovers. Sagging voltage rails vs strong regulated ones in amps; impedance drops, phase shifts and efficiency in speakers... Bloody engineers like to complicate things.
Manufacturers know that regular Joe is much more impressed by amps going louder quicker in the demo room and will manipulate with this in their circuit designs. But what else is new.
Few things one needs to consider about attenuation differences between amps.
1) Logarithmic vs Linear volume control. The first one will go louder progressively delivering into "chunks" (0.01W > 0.1W > 1W > 2.5W > 5W > 10W > 25W > 50W). Second one will go louder more quicker and more evenly spread ( 1, 2, 3, 5, 6...), sometimes giving out all the good clean watts before you reached 12 o'clock position. Logarithmic is the safe way to go since chances of accidentally blowing your speakers are slim, but it does feel emasculating to some who prefer the illusion of "9 o'clock position allready too loud, so much power."
2) Attenuation coefficient (Signal to Noise Ratio and Dynamic Peak). SNR 90db and DP 106db will go louder quicker than SNR 80db and DP 106db. Later one will sound more laidback and you will need to turn it up to get the best of it.
3) Passive attenuation vs Gained. First one just outputs 0-100% of the preamp line signal without applying gain, which leaves the gain to be applied in the power amp section (like with Exposure amps). Gain in the preamp will add db's and continue to add in the power section. The later ones I've noticed would go louder quicker, but it's not a general rule.
4) External vs Embedded Loudness curve. External is when you get to push a button to get more db in low and high frequencies at lower listening volumes. Additional loudness compensates for our hearing insensitivity to low and high frequencies for quiet listening aka Fletcher–Munson curve. Its expected for you to shut it off once you go past (usually) 8-9 o'clock, however some never do. Embedded loudness is applied by a circuit in the preamp in a way you don't get to enable/disable it. It automatically reduces from 100% to 0% added loudness once you turn the volume knob past 8-9 o'clock. Some amps have variable loudness knobs (old Yamahas) and some have no loudness compensation at all.
So basically how loud an amp gets is a function of both preamp and power amp circuitry. The preamp is tuning the little voltage (coming from your source component, cd, tape, tt, ipod) to modify the big one (coming from the wall socket) thus making weak signal go bigger - amplifiers amplify. However, similar to servo steering in cars, not all things are equal. If you go louder quicker it doesn't necessarily mean you got lots more on tap. In matter of fact it's most likely you don't and your amp will go into clipping if you crank it up even further.
Now I shared my thoughts from preamp attenuation perspective but consider there is a lot more to be said about the power section and its relation to speakers and especially crossovers. Sagging voltage rails vs strong regulated ones in amps; impedance drops, phase shifts and efficiency in speakers... Bloody engineers like to complicate things.
Manufacturers know that regular Joe is much more impressed by amps going louder quicker in the demo room and will manipulate with this in their circuit designs. But what else is new.
eggontoast
Well-known member
Viking said:
How do you know what voltage level you are getting from the headphone output, does the Brennan give you a dBV level ?
To do a proper comparison feed both amps with the line out signal then compare, but the volume pot position is still not an indicator as it depends on the gain of the amp.
Facebook
Twitter
Instagram