Underpowered amps vs overpowered amps
- Thread starter mandark
- Start date
Hi,
I found this late. In the following, let me add my bits (some of this is already raised):
The Underpowered Amp:
This is bad for several reasons:
1) Firstly, the speakers' capabilities will not be utilized, there will be no dynamics etc, and hence this will result in dissatisfaction with the audio quality.
2) Secondly this is potentially dangerous for both the amp and the speakers. When the amp is asked to deliver more power to the speakers than it is capable of (because of its poor power supply section or the output stage), it will clip. This means that the usual sinusoidal wave form of the signal has its tops (crests) and bottoms (troughs) chopped off to flat shapes. The flat portions actually are direct currents (DC) and are bad for both the amp and the speakers. This will result in overheating of the amp and may damage the amp in case clippings happen regularly and depending on how severe is the clipping (i.e., how long are the flat portions). The DC in the output signal is even worse for the speakers for 2 reasons: a) Fourier analysis of the clipped wave form will show that there are very high frequency components in the output signals resulting from the flat portions. This can damage the tweeters irreversibly, and b) the DC will also result in overheating of ALL speaker drivers and they may give in beyond a point.
In the above, I have assumed the amp to be a solid state (SS). Although there exist valve amps (Berning, for example) which do not have transformers in the out stage, most of the valve amps do have one transformer each per channel at the output stage. Transformers do not pass the DC, because according to the laws of electrodynamics, only a changing current can induce a changing magnetic field which in turn can induce a current in the secondary of the transformer. Hence, clipping in valve amps with transformers at the output stage are not dangerous to the speakers, but can be harmful to the amp itself.
The Overpowered Amp
This is good for sane adults. Speakers will love the powerful signal from the amp and will show what they are capable of. Much before speakers can tear off the diaphragms (as has been commented in a previous post), the diaphragms will lose any harmonic response and will start distorting quite badly. The listener will know without any problems what are the safe limits on the volume knob for a particular amp-speakers combo. However, with unattended children (or teenagers) or even with attended/unattended insane adults around, there is a potential danger of damaging the speaker coils (because of overheating) and even the cones (because of more displacement than they are designed to handle).
Speaker Parameters
At the end, I like to point out one simple thing that I see many people mentioning in this forum; and, that is the power rating of a speaker. As arj already pointed out in this thread, speakers usually are passive devices and the power usually mentioned in the spec sheet is the maximum power when delivered from an amp they are capable of handling for safe and sustained operation. As explained above, for sane adults, this figure is mostly irrelevant, unless they are unusually low (usually they are 100Watts or above). Sensitivity is certainly one important parameter when it comes to the drivability of a certain amp for certain speakers. Equally important is the impedance of the speakers as a function of frequency (this also includes phase variation of the load with frequency). At certain frequency bands, the speakers may be a lot harder to drive )because of a dip of the resistance of the speakers, for example) resulting in a degradation of the final audio quality. Nominal impedance as usually given in the spec sheets is only a very rough indicator, and is given as only a resistive load without any phase angles. If the plots of above data are not available easily, the only way is to listen to the combination, which is always the best option.
Regards.
I found this late. In the following, let me add my bits (some of this is already raised):
The Underpowered Amp:
This is bad for several reasons:
1) Firstly, the speakers' capabilities will not be utilized, there will be no dynamics etc, and hence this will result in dissatisfaction with the audio quality.
2) Secondly this is potentially dangerous for both the amp and the speakers. When the amp is asked to deliver more power to the speakers than it is capable of (because of its poor power supply section or the output stage), it will clip. This means that the usual sinusoidal wave form of the signal has its tops (crests) and bottoms (troughs) chopped off to flat shapes. The flat portions actually are direct currents (DC) and are bad for both the amp and the speakers. This will result in overheating of the amp and may damage the amp in case clippings happen regularly and depending on how severe is the clipping (i.e., how long are the flat portions). The DC in the output signal is even worse for the speakers for 2 reasons: a) Fourier analysis of the clipped wave form will show that there are very high frequency components in the output signals resulting from the flat portions. This can damage the tweeters irreversibly, and b) the DC will also result in overheating of ALL speaker drivers and they may give in beyond a point.
In the above, I have assumed the amp to be a solid state (SS). Although there exist valve amps (Berning, for example) which do not have transformers in the out stage, most of the valve amps do have one transformer each per channel at the output stage. Transformers do not pass the DC, because according to the laws of electrodynamics, only a changing current can induce a changing magnetic field which in turn can induce a current in the secondary of the transformer. Hence, clipping in valve amps with transformers at the output stage are not dangerous to the speakers, but can be harmful to the amp itself.
The Overpowered Amp
This is good for sane adults. Speakers will love the powerful signal from the amp and will show what they are capable of. Much before speakers can tear off the diaphragms (as has been commented in a previous post), the diaphragms will lose any harmonic response and will start distorting quite badly. The listener will know without any problems what are the safe limits on the volume knob for a particular amp-speakers combo. However, with unattended children (or teenagers) or even with attended/unattended insane adults around, there is a potential danger of damaging the speaker coils (because of overheating) and even the cones (because of more displacement than they are designed to handle).
Speaker Parameters
At the end, I like to point out one simple thing that I see many people mentioning in this forum; and, that is the power rating of a speaker. As arj already pointed out in this thread, speakers usually are passive devices and the power usually mentioned in the spec sheet is the maximum power when delivered from an amp they are capable of handling for safe and sustained operation. As explained above, for sane adults, this figure is mostly irrelevant, unless they are unusually low (usually they are 100Watts or above). Sensitivity is certainly one important parameter when it comes to the drivability of a certain amp for certain speakers. Equally important is the impedance of the speakers as a function of frequency (this also includes phase variation of the load with frequency). At certain frequency bands, the speakers may be a lot harder to drive )because of a dip of the resistance of the speakers, for example) resulting in a degradation of the final audio quality. Nominal impedance as usually given in the spec sheets is only a very rough indicator, and is given as only a resistive load without any phase angles. If the plots of above data are not available easily, the only way is to listen to the combination, which is always the best option.
Regards.
ShaQ.Blogs
Active Member
If i had "cut and pasted from a source", dont you think google would fetch you that result?
By the way, my explanation was not exactly right. But the idea was to understand that it revolves around mismatch in terms of power with the combination of pushing it too hard.
In reality, dc current theory is not possible. If there was continuous dc, then user wud notice it dead on immediately.
This basically happens with over powering, playing with amp gains, and amp entering into clip mode where it tends to generate more power, and when there is not enough head room for speakers, then the thermal failure can occur.
End of the day, no matter how well matched the speakers & the amp are, there is always a way to screw up your speakers.
Hence dont experiment if you dont understand know what you are upto.
As a basic rule, I would advice to play at a max 80% of amp's potential. So plan for enough headroom in advance, both amp & speakers.
I might be a newbie to the HiFi world and using this stuff. But, technical knowledge is on a different league by itself
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i think in this neverending debate people should look for workarounds. Clipping protection circuit like what i found in Denon should be the key to this problem when we are afraid of damaging amps and speakers.
An amplifier must be 1.5X times the power handling capability of speaker it is driving. The music signal has very high average to peak ratio with respect to its program content.
Underpower amplifiers clip easily and which can burn the voice coils easily especially tweeters.
Hope this Helps.
Underpower amplifiers clip easily and which can burn the voice coils easily especially tweeters.
Hope this Helps.
If a speaker is rated 10 to 100 Watts as Power (without mentioning which one is average or peak) then what will be the amp power required?
To add to the above question from the below info am I driving my speakers into unsafe operation? Max volume knob position 9'O Clock most of the time (All of my sources output voltage is about 2Vrms)
My speaker specs say nominal impedance of 4 - 8 ohms and recommended amplifier as 15-120W. It doesn't mention the peak wattage it can take for short periods.
But my amp specs say continuous output power of >80W into 8 ? and 4 ?. And IHF Dynamic Power 145W @ 8 Ohms, 220W @ 4 Ohms and 290W @ 2 Ohms.
Saikat,
As far as I understand, this just means that the max rms power delivered per channel from the amp this speaker can handle without damage to itself is 100 Watts. I'd interpret this information as a rough guide for safe and sustained operation for the speakers.
At the same time, it needs at least 10 Watts of power per channel so that satisfactory performance from the speakers can be expected. Of course, all this would depend also on the room, and specs for some speakers also mention the recommended max and min room sizes. For certain speakers, too small a room would result in boominess resulting from wall-reflections, and for certain other speakers satisfactory db (loudness) level may not be achieved for rooms larger than a max size.
Ravi,
I'd answer your query in the same way as above. From the data you have provided, I'd interpret the 120W to be the max rms sustained power per channel from the amp your speakers can safely handle. For safe listening levels, which is about 75-80 db, 120Watts limit is much much above the actual watts that your amp is delivering to the speakers (per channel), assuming your speakers have a sensitivity not much below 85 db/W/m (btw, a sensitivity significantly below 84-85 db is very unusual, at least I have never come across such speakers). So if you have sane listening levels, you should never have to worry about the max power rating of the speakers, as I have already expressed in my previous reasonably detailed post. For me, it's an irrelevant piece of information.
Regards.
OT:
Saikat, I am terribly sorry that I have not yet been able to answer your query in your e-mail. I have tried my best, but I have almost no experience in the video part of your query. You will soon get an answer from me regarding only the audio part.
Thank you asit da. I did check that Denon have built in clipping protection feature which auto shuts off the amp if clipping is detected.
However my other remaining concern is that if a speaker is rated 10-100 Watts then can I asume that the 100 Watt rating is the max supported RMS (meaning the speaker can play inputs at 100 Watts for quite some time without damaging itself ) or the max supported short term power is 100 Watts (meaning that 100 Watts is something which it can handle only instantaneously and a continuous supply of that power level will burn out the speakers.
The problem is that Speaker manufacturers are not so specific in opening up these details while publishing their specs.
Saikat,
If you read my answer to Ravi's query in my previous post, I think you will find an answer to your last question as well. I do not think for sane listening level with allowance for very respectable dynamic headroom, it matters at all if the 100W as quoted in the speakers' specsheet is the max rms or the max peak power from amp supported, because with speakers with any reasonable sensitivity (around 85 db and above), that amount is way above the actual power your amp is delivering to the speakers per channel (typically a few tens of Watts).
Perhaps you can tell me which exact speakers you have in mind. I then can try to look into the spec. You are right, usually the specs given are very very incomplete, not only for speakers but also for all electronics.
Regards.
If you read my answer to Ravi's query in my previous post, I think you will find an answer to your last question as well. I do not think for sane listening level with allowance for very respectable dynamic headroom, it matters at all if the 100W as quoted in the speakers' specsheet is the max rms or the max peak power from amp supported, because with speakers with any reasonable sensitivity (around 85 db and above), that amount is way above the actual power your amp is delivering to the speakers per channel (typically a few tens of Watts).
Perhaps you can tell me which exact speakers you have in mind. I then can try to look into the spec. You are right, usually the specs given are very very incomplete, not only for speakers but also for all electronics.
Regards.
Asit da, Speakers are Aviano 6 floorstands "rated 15-150 Watts" and Aviano 2 bookshelves "rated 10-120 Watts" and the amp is Denon 1911 rated at 90W per channel at 8ohms impedance and 125 W @ 6ohms.
dragonxwas
New Member
Logically speaking :
It all depends on the speaker or the load driven by the amp..
Imagine theoretically ( most of the other factors are constant) an amp with capablity to drive at the maximum 50W @ 8ohms but you have a speaker which is 8ohms and can do 100W..
No matter how high you drive the amp It wont be able to damage the speaker, unless and otherwise the amp designer used a poor topology and the amp at its clipping stage pushes constant Dc to the speaker..
now you ask why constant DC kills the speaker, simple your speakers voice coil is cooled by the up and down movement of diaphram acting as a fan, when you give constant DC to your speakers your speakers become locked at its Xmax (the excursion limit, the mechanical limit of the diaphram to move from its initial position to outside) and hence no air, and as resistance increases with heat, more heat will be produced in voice coil and it will get burnt..
Now eventhough the speaker is stuck on Xmax , no air flow it is locked with Dc of 50W, no damage will occour as the coil is made to withstand 100W of power..Except due to constant clipping and heating the speaker's voice coil insulation might become compromised and will not last longer...
Another question commonly asked :
Say my speaker is rated at 100hz-20Khz and I play a 60Hz note through it will it damage my speaker ? the answer is yes and no..
You see a speakers ability to reproduce notes is given by the Weight of the cone and the suspension stiffness ( SPIDER), the heavier the lower notes, the lighter the higher notes.
Now how will playing a lower note lesser than the drivers resonant frequency(lowest note the driver can play) kill the speaker, its simple, the driver due to stiffness of suspension and the weight of the cone, will not move as intended and cause the same effect when Dc passes through the voice coil..
Secondly it also depends on the voice coil material to some extent , some voice coil material like made out of alloys have a constant impedance at all notes 20-20000Hz but in real life at every frequency the impedance of the voice coil differs, It reduces to some extent at lower frequency and increases to some extent at higher frequencies..
due to low impedance the amp will clip quickly and will pass through Dc to the speakers
which will have the same effect..
Now the other answer is quite simple, if your speaker is rated at 100-20000hz then it should not in any circumstance produce anything lesser than 100Hz. this is kept in mind by some manufacturers and improvised in their crossover designs and so the speakers will always produce 100Hz+..so damage doesn't occour...sadly this phenomenon is seldom rarely seen..
So either playing lower notes or using underpowered amps is unlikely to damage your speakers..So call it not serious reason for speaker damage..
Overpowered amp and underpowered speaker:
when a speaker is overdriven, there is always excess of mechanical stress on the suspension,the cone supports and the voice coil.
as more current flows through the voice coil the voice coil heats up and destroys itself..
By no way as some of you members think, that an over powered amp can tear the cone of a speaker, the only damage you could see on an overdriven speaker is burnt voice coil..
So keep it as moderately serious cause for speakers being fried..
the most and the number 1 reason for speaker getting Fried is :
Wrong Impedance matching, you see as my older points you can know the only cause of speakers being fried is due to heating up of voice coil.
You see most amps have a minimum rated stability impedance, say 4ohms 8ohms 6ohms Under no circumstances one must use speakers below the amp's rated impedance.
the only thing which happens when the amp drives a near short load (lesser than its rated impedance) is it clips moderately at first, as you further try to drive the amp, its condition deteriorates fast and sends clips and dc out, which like I said kills your speakers...
So neither overpowered amps are dangerous nor the underpowered ones..Just do proper impedance matching....
Source : Acoustic Researcher, DiY'r , Speaker+amp fanatic..
P.S : most of the posters above don't know why an amp clips, to just give you a jest of it its because it is forced to drive a harder load than it should, load if you think in terms of amplifier is always the impedance of the speaker and not the wattage...
Also after reading some posts above, I have come to know that people tend to think its the Dc from clips destroys the tweeters, its not the case if you have a crossover which keeps this thing in mind, now usually in low-mid high end speakers the crossover section for a tweeter consists of a inductor and a cap in series and a coil in parallel, the crossovers are devices which are meant for Ac signals , when a Dc signal passes it completely bypasses the crossover and feeds is direct current into the tweeter the tweeter will not die even if it has a constant Dc source as the factors regarding tweeters are completely different, why a tweeter dies is simply because of low frequency being pumped through it because of bypassed crossover which causes the overheating of coil and at the end the mechanical destruction of the diaphram due to heat, most tweeter diaphrams are made out of polymers or plastics coated with films of various material to give it aural flavour..the plastic easily melts due to heat and the disfiguring of the diaphram which causes death...
It all depends on the speaker or the load driven by the amp..
Imagine theoretically ( most of the other factors are constant) an amp with capablity to drive at the maximum 50W @ 8ohms but you have a speaker which is 8ohms and can do 100W..
No matter how high you drive the amp It wont be able to damage the speaker, unless and otherwise the amp designer used a poor topology and the amp at its clipping stage pushes constant Dc to the speaker..
now you ask why constant DC kills the speaker, simple your speakers voice coil is cooled by the up and down movement of diaphram acting as a fan, when you give constant DC to your speakers your speakers become locked at its Xmax (the excursion limit, the mechanical limit of the diaphram to move from its initial position to outside) and hence no air, and as resistance increases with heat, more heat will be produced in voice coil and it will get burnt..
Now eventhough the speaker is stuck on Xmax , no air flow it is locked with Dc of 50W, no damage will occour as the coil is made to withstand 100W of power..Except due to constant clipping and heating the speaker's voice coil insulation might become compromised and will not last longer...
Another question commonly asked :
Say my speaker is rated at 100hz-20Khz and I play a 60Hz note through it will it damage my speaker ? the answer is yes and no..
You see a speakers ability to reproduce notes is given by the Weight of the cone and the suspension stiffness ( SPIDER), the heavier the lower notes, the lighter the higher notes.
Now how will playing a lower note lesser than the drivers resonant frequency(lowest note the driver can play) kill the speaker, its simple, the driver due to stiffness of suspension and the weight of the cone, will not move as intended and cause the same effect when Dc passes through the voice coil..
Secondly it also depends on the voice coil material to some extent , some voice coil material like made out of alloys have a constant impedance at all notes 20-20000Hz but in real life at every frequency the impedance of the voice coil differs, It reduces to some extent at lower frequency and increases to some extent at higher frequencies..
due to low impedance the amp will clip quickly and will pass through Dc to the speakers
which will have the same effect..
Now the other answer is quite simple, if your speaker is rated at 100-20000hz then it should not in any circumstance produce anything lesser than 100Hz. this is kept in mind by some manufacturers and improvised in their crossover designs and so the speakers will always produce 100Hz+..so damage doesn't occour...sadly this phenomenon is seldom rarely seen..
So either playing lower notes or using underpowered amps is unlikely to damage your speakers..So call it not serious reason for speaker damage..
Overpowered amp and underpowered speaker:
when a speaker is overdriven, there is always excess of mechanical stress on the suspension,the cone supports and the voice coil.
as more current flows through the voice coil the voice coil heats up and destroys itself..
By no way as some of you members think, that an over powered amp can tear the cone of a speaker, the only damage you could see on an overdriven speaker is burnt voice coil..
So keep it as moderately serious cause for speakers being fried..
the most and the number 1 reason for speaker getting Fried is :
Wrong Impedance matching, you see as my older points you can know the only cause of speakers being fried is due to heating up of voice coil.
You see most amps have a minimum rated stability impedance, say 4ohms 8ohms 6ohms Under no circumstances one must use speakers below the amp's rated impedance.
the only thing which happens when the amp drives a near short load (lesser than its rated impedance) is it clips moderately at first, as you further try to drive the amp, its condition deteriorates fast and sends clips and dc out, which like I said kills your speakers...
So neither overpowered amps are dangerous nor the underpowered ones..Just do proper impedance matching....
Source : Acoustic Researcher, DiY'r , Speaker+amp fanatic..
P.S : most of the posters above don't know why an amp clips, to just give you a jest of it its because it is forced to drive a harder load than it should, load if you think in terms of amplifier is always the impedance of the speaker and not the wattage...
Also after reading some posts above, I have come to know that people tend to think its the Dc from clips destroys the tweeters, its not the case if you have a crossover which keeps this thing in mind, now usually in low-mid high end speakers the crossover section for a tweeter consists of a inductor and a cap in series and a coil in parallel, the crossovers are devices which are meant for Ac signals , when a Dc signal passes it completely bypasses the crossover and feeds is direct current into the tweeter the tweeter will not die even if it has a constant Dc source as the factors regarding tweeters are completely different, why a tweeter dies is simply because of low frequency being pumped through it because of bypassed crossover which causes the overheating of coil and at the end the mechanical destruction of the diaphram due to heat, most tweeter diaphrams are made out of polymers or plastics coated with films of various material to give it aural flavour..the plastic easily melts due to heat and the disfiguring of the diaphram which causes death...
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Hi Saikat,
I again apologize for a late reply. Too many marriage invitations in the evenings that we had to attend the last few evenings, and as a result I had no free time.
Well, I have looked at the specs of both the Aviano 6 speakers and also the Denon 1911 AVR. Based on the minimal specs given, the simple-minded conclusion would be that they are compatible with each other. However, the actual fact may go deeper than that. For example, the rated power of this 7 channel avr is 90W x 7 at 8 Ohms which I find very hard to believe, given that the max total power consumption given in the specs is around only 450 Watts. Contrast that with the Denon 2-channel integrated amp PMA 2010AE which is rated at 85W x2 and the max total power consumption given in the spec to be more than 300 W. I have generally very little or no direct experience with AVRs, and hence I'd invite users of the Denon 1911 AVR to comment on it. But generally I'd be very surprised if this AVR can be robust enough to produce 90W@8 Ohms per channel with all channels driven. A second point is about the nominal impedance of 4-8 Ohms as given in the specs of the aviano 6 speakers. The 1911 avr is rated at 125 w per channel at 4 Ohm (here again I have the same suspicion as before). From this it appears that the avr is stable at a 4 Ohm load. So now the question is if the Aviano 6 speaker's impedance goes substantially below 4 Ohms or not. Most well-constructed 2-channel amps are stable against a load of 2 Ohms, some even rate themselves at 1 Ohm. However, looking at the specs of the avr, it does not give me the impression that it will withstand a dip in impedance below 4 Ohms. If the aviano impedance really drops below 4 Ohms (usually that would happen at low frequencies), there would be a cause for concern. Please remember that the so-called "nominal impedance" is a dubious term these days. In older days, there was a precise German norm (DIN XXXX) for this, but nowadays I feel that different manufacturers have different meanings for it.
The best is to find out from actual users of this combo or a combo quite close to it. If this combo (aviano 6 fronts + denon 1911) works well, there are bound to be many owners around the world that you can find simply by googling, and then see what the actual users have to say. Better still (if you are experienced enough) is to listen to this combo, if that is possible.
I hope I find some time tomorrow to comment on dragonxwas's views as given in his last post.
Regards.
Regards.
In that case you can choose the power amp upto 150W easily without destroying your speakers.
This is a very good observation Asit da. I doubt the specs are deceiving for all similar multichannel AVRs in the same range as this one. May be in reality they will not drive all at 90Watt at the same time by logic that fronts will be active most of the time and surrounds only occasionally where they will cut down some power from the front.. just my guess though.
Denon 1911 is rated 125Watts at 6ohms. Will that make any difference? I found the below link on Denon website which talks of a clipping protection feature for handling similar instances. But not sure if this will exactly handle the problem you were elaborating.
Can I use 4 ohm loudspeakers with my Denon receiver or power amplifier?
The "Protection" indicator comes on
I agree Asit da, I think the biggest problem it seems to be is knowing all the figures right as compared to what is published, or rather understanding the "Fineprints".
Will surely look forward to this and post accordingly.
No, that is the biggest problem and my guesswork has its limits
and hence the alternative I have is to keep bugging people like you for guidance.Saikat,
I somehow misread the spec as 125W at 4 Ohms when the correct impedance would be 6 Ohms. However, I would still expect the 1911 avr to be stable at 4 Ohm, because for a reasonable avr that many people buy it would be very surprising if it was otherwise, but of course this avr segment is a whole new area for me and naturally I cannot guarantee anything just from guesswork and a few specs. So if you are thinking seriously about buying this avr, you please ensure the stability of the avr at lower impedances, at the same time look at also the impedance vs frequency curve for the aviano speakers (you may have to ask the manufacturer for that) to see if they are really going below 4 Ohms. You also may seriously start considering the bigger brother 2311 which is more powerful. Since you also plan to listen to 2-channel music through the avr, you should compare the stereo music performance of the avrs (2311 or 1911) directly against a dedicated 2-channel amp (like the 710 or the 1510) at the profx store and see if you are satisfied. I'd expect the 2311 to do better than the 1911 in this test. However, I know there are always monetary constraints and one simply cannot bypass that.
The clipping protection circuitry you mentioned, although designed to protect the avr from clipping, may be a pain in the neck in actual use. It will be a serious annoyance to you while watching a movie or listening to music if the clipping protection suddenly comes into business. A dear friend of mine had a 2-channel amp that had such an over-zealous protection system that it completely spoiled his music sessions, ultimately he got rid of both the amp and the speakers. That combination simply did not work. I suppose the gist is that the clipping protection while it perhaps will save your amp and speakers will actually spoil your listening and watching sessions, the very reason you are going to buy these equipments.
Regards.
I somehow misread the spec as 125W at 4 Ohms when the correct impedance would be 6 Ohms. However, I would still expect the 1911 avr to be stable at 4 Ohm, because for a reasonable avr that many people buy it would be very surprising if it was otherwise, but of course this avr segment is a whole new area for me and naturally I cannot guarantee anything just from guesswork and a few specs. So if you are thinking seriously about buying this avr, you please ensure the stability of the avr at lower impedances, at the same time look at also the impedance vs frequency curve for the aviano speakers (you may have to ask the manufacturer for that) to see if they are really going below 4 Ohms. You also may seriously start considering the bigger brother 2311 which is more powerful. Since you also plan to listen to 2-channel music through the avr, you should compare the stereo music performance of the avrs (2311 or 1911) directly against a dedicated 2-channel amp (like the 710 or the 1510) at the profx store and see if you are satisfied. I'd expect the 2311 to do better than the 1911 in this test. However, I know there are always monetary constraints and one simply cannot bypass that.
The clipping protection circuitry you mentioned, although designed to protect the avr from clipping, may be a pain in the neck in actual use. It will be a serious annoyance to you while watching a movie or listening to music if the clipping protection suddenly comes into business. A dear friend of mine had a 2-channel amp that had such an over-zealous protection system that it completely spoiled his music sessions, ultimately he got rid of both the amp and the speakers. That combination simply did not work. I suppose the gist is that the clipping protection while it perhaps will save your amp and speakers will actually spoil your listening and watching sessions, the very reason you are going to buy these equipments.
Regards.
Hi dragonxwas,
I am not an expert in electronics and not at all a person gifted with diy skills, neither am I an audio-guru of any kind. But I felt there are a few things mentioned in your post which may be a bit misleading. Please take this post in the right spirit. BTW, I see that you have recently joined our forum, and let me take this opportunity to welcome you.
You have rightly put a lot of importance on the issue of impedance matching and the lowest impedance an amp is stable against. There have been detailed discussions in many threads of this forum, where people including me have discussed this issue at length, and various other issues like sensitivity and efficiency, speaker excursions and distortions etc etc.
Based on the above, your comment "most of the posters above don't know why an amp clips" is at the least a bit presumptuous.
Unfortunately, I do not have the time at the moment to go into details of your post. I will just comment on your last point.
You do not think clipping would harm speakers, because the DC can be bypassed using a protection circuit. I do not think this is true. That protection circuit (modification to the crossover) will take care of DC alright, but then one needs to understand what is the Direct Current (DC) in the clipping context. Unfortunately, these days I am always in a hurry, and I did not take the extra care of explaining these in detail in post #22 (http://www.hifivision.com/surround-...ed-amps-vs-overpowered-amps-3.html#post227462).
Let us concentrate on a sinusoidal wave form (hence comprising of a single frequency). In general, a musical signal comprises of a wave-form which is a linear superposition of many such sinusoidal wave forms each corresponding to a definite frequency. For our purposes, a simple sinusoidal wave-form is enough because the actual musical wave-form can be broken up into these sinusoidal ones.
Now, when clipping occurs, there will be flat portions near the crest and the trough of the waveform. The clipped waveform can be analyzed through a Fourier decomposition. This actually will lead to the following: the clipped waveform (originating from clipping of a sinusoidal waveform of a single frequency f) is actually a superposition of many sinusoidal wave-forms corresponding to the fundamental frequency f, and its odd harmonics 3f, 5f, 7f ... (the odd harmonics appear if the clipping is symmetric around zero, that is, between top of the waveform and the bottom). There is one more twist to the tale: amplitude of the waveform corresponding to the fundamental frequency f after clipping is significantly larger than the amplitude of the original sinusoidal wave-form with the freq f. Amplitudes of the waves corresponding to the harmonics like 3f, 5f etc are monotonically lower, however, they are significant (that is, not very small). Now remember that the power a particular wave carries is proportional to the square of the amplitude.
From the above, one concludes that after clipping of sinusoidal waveform of a single frequency f, there are many sinusoidal waves. The fundamental one corresponding to the freq f now carries significantly more power. In addition, there are other waves present (corresponding to higher frequencies 3f, 5f etc) which also carry significant but lower amount of power.
Now, remember that the tweeters are really delicate objects, surely much more delicate than woofers. If a speaker is rated to handle 100W of power, the tweeter is probably good enough for 10 Watts or at best 20 Watts. The crossover saves speakers by forwarding high frequencies to the tweeters and lower frequencies to the woofers. There is of course no sharp demarcation at the crossover frequency, some low freq also go through the crossover to the tweeters and vice versa (of course this a different topic altogether, and tweeter damage can also occur from low freq going to the tweeters).
Now one realizes why clipping is so dangerous to the tweeters. Such a delicate thing is subjected to significantly more power, even from the component of the wave with the fundamental frequency f (this is a point not usually mentioned) and also all the power (albeit lower) from the components having higher frequencies (odd harmonics of f).
The bypass/protection circuit you mention in your post is designed to bypass DC, but it will do NOTHING to protect the tweeters from these clipped signal which will carry significantly higher power (both from freq f components and higher freq components).
The reason your bypass will not work is the clipped waveform is NOT DC. It would be pure DC if the flat portions would continue for all time. But a clipped signal is not like that, it has DC segments, but overall the signal is still AC (the flat portions appear periodically above and below zero). People colloquially call it a DC, but it is actually not. It is actually a more complicated AC waveform as I have elaborated above, comprising of many frequencies. At best it can be called a DC segment, a segment when the signal does not change in magnitude or direction over a restricted period of time. It is also in this very restricted sense, in my post #22, I called it a DC. There was another reason for me to call it a DC in reference to the valve amps with transformers in the output stage. It was then easy for me to explain why that steady portion will not go through the transformer primary into the secondary because of its property of not changing with time (albeit for a restricted period of time).
There are a few other parts in your post I am not entirely happy with. However, I shall stop here.
Whatever I have written are established facts and analysis of physics. I must say though there may be other reasons or explanations for tweeter damage occurring from clipping. Some physicists have worked on these things. However, the scenario presented here remains as the most promising explanation, although I have seen some heated and emotional discussions (including sarcasms) in diy forums even on the stuff discussed here.
Regards.
I am not an expert in electronics and not at all a person gifted with diy skills, neither am I an audio-guru of any kind. But I felt there are a few things mentioned in your post which may be a bit misleading. Please take this post in the right spirit. BTW, I see that you have recently joined our forum, and let me take this opportunity to welcome you.
You have rightly put a lot of importance on the issue of impedance matching and the lowest impedance an amp is stable against. There have been detailed discussions in many threads of this forum, where people including me have discussed this issue at length, and various other issues like sensitivity and efficiency, speaker excursions and distortions etc etc.
Based on the above, your comment "most of the posters above don't know why an amp clips" is at the least a bit presumptuous.
Unfortunately, I do not have the time at the moment to go into details of your post. I will just comment on your last point.
You do not think clipping would harm speakers, because the DC can be bypassed using a protection circuit. I do not think this is true. That protection circuit (modification to the crossover) will take care of DC alright, but then one needs to understand what is the Direct Current (DC) in the clipping context. Unfortunately, these days I am always in a hurry, and I did not take the extra care of explaining these in detail in post #22 (http://www.hifivision.com/surround-...ed-amps-vs-overpowered-amps-3.html#post227462).
Let us concentrate on a sinusoidal wave form (hence comprising of a single frequency). In general, a musical signal comprises of a wave-form which is a linear superposition of many such sinusoidal wave forms each corresponding to a definite frequency. For our purposes, a simple sinusoidal wave-form is enough because the actual musical wave-form can be broken up into these sinusoidal ones.
Now, when clipping occurs, there will be flat portions near the crest and the trough of the waveform. The clipped waveform can be analyzed through a Fourier decomposition. This actually will lead to the following: the clipped waveform (originating from clipping of a sinusoidal waveform of a single frequency f) is actually a superposition of many sinusoidal wave-forms corresponding to the fundamental frequency f, and its odd harmonics 3f, 5f, 7f ... (the odd harmonics appear if the clipping is symmetric around zero, that is, between top of the waveform and the bottom). There is one more twist to the tale: amplitude of the waveform corresponding to the fundamental frequency f after clipping is significantly larger than the amplitude of the original sinusoidal wave-form with the freq f. Amplitudes of the waves corresponding to the harmonics like 3f, 5f etc are monotonically lower, however, they are significant (that is, not very small). Now remember that the power a particular wave carries is proportional to the square of the amplitude.
From the above, one concludes that after clipping of sinusoidal waveform of a single frequency f, there are many sinusoidal waves. The fundamental one corresponding to the freq f now carries significantly more power. In addition, there are other waves present (corresponding to higher frequencies 3f, 5f etc) which also carry significant but lower amount of power.
Now, remember that the tweeters are really delicate objects, surely much more delicate than woofers. If a speaker is rated to handle 100W of power, the tweeter is probably good enough for 10 Watts or at best 20 Watts. The crossover saves speakers by forwarding high frequencies to the tweeters and lower frequencies to the woofers. There is of course no sharp demarcation at the crossover frequency, some low freq also go through the crossover to the tweeters and vice versa (of course this a different topic altogether, and tweeter damage can also occur from low freq going to the tweeters).
Now one realizes why clipping is so dangerous to the tweeters. Such a delicate thing is subjected to significantly more power, even from the component of the wave with the fundamental frequency f (this is a point not usually mentioned) and also all the power (albeit lower) from the components having higher frequencies (odd harmonics of f).
The bypass/protection circuit you mention in your post is designed to bypass DC, but it will do NOTHING to protect the tweeters from these clipped signal which will carry significantly higher power (both from freq f components and higher freq components).
The reason your bypass will not work is the clipped waveform is NOT DC. It would be pure DC if the flat portions would continue for all time. But a clipped signal is not like that, it has DC segments, but overall the signal is still AC (the flat portions appear periodically above and below zero). People colloquially call it a DC, but it is actually not. It is actually a more complicated AC waveform as I have elaborated above, comprising of many frequencies. At best it can be called a DC segment, a segment when the signal does not change in magnitude or direction over a restricted period of time. It is also in this very restricted sense, in my post #22, I called it a DC. There was another reason for me to call it a DC in reference to the valve amps with transformers in the output stage. It was then easy for me to explain why that steady portion will not go through the transformer primary into the secondary because of its property of not changing with time (albeit for a restricted period of time).
There are a few other parts in your post I am not entirely happy with. However, I shall stop here.
Whatever I have written are established facts and analysis of physics. I must say though there may be other reasons or explanations for tweeter damage occurring from clipping. Some physicists have worked on these things. However, the scenario presented here remains as the most promising explanation, although I have seen some heated and emotional discussions (including sarcasms) in diy forums even on the stuff discussed here.
Regards.
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Asit da, I think testing the same speakers against a 2 channel amp is a better idead. Thanks and I will give that a try. I may find out the volume level in % of total volume that drives the speaker ina manner suitable for home listening.
2311 costs 70,000
i may not be able to go for it. However can you tell me if I am running the music at 40% of volume will that also have potential to run into clipping?Apart from that I am on lookout for some audio track which deliberately can lower speaker impedance, preferably a musical track. I belive getting impedance curve or speaker may not be a possiblity since this may be confidential data of the manufacturer.
While I am going to hear out myself the performance of speakers with a 2 channel receiver following the suggestion of Asit da and post fedbacks, I found the below article on one review in the following link
3D Receivers shoot-out: Denon AVR-1911, Pioneer VSX-1020-K, Onkyo TX-SR608 | HyperSensory.com
Go to the very end and check what the site admin has posted as response to a comment, I am quoting it below
While one receiver may be rated at 90watt and another at 110watt, some assume that the rating assumes all channels driven. This is not true, which is of course misleading. Yet, there is almost never a case when all channels need to be driven at full power. No movie or especially music track (as most of them are done in stereo) try to drive speakers at full power on all channels. And no one would listen to such material at full volume either. This fact makes the ratings almost meaningless. In truth, there is only one reason to have those ratings - to ensure that when you buy speakers or receiver, you are able to drive the speakers to a desired volume level without risking damaging speakers or equipment. I have a new 7.1 90watt Denon and some pretty decent full tower speakers rated at 250watt MAX. Yet, I have never needed to turn the volume knob more than 2/3 of the way. It just gets ridiculously loud after that. Of course this also depends on your speaker efficiency, but still - for most installations a 90watt receiver will drive a full set of speakers at desired volume without clipping or going into protection mode (given enough air-flow and following installation recommendations).
So if I am listening to music only in 2 channel mode then 90 watts per channel is fine to drive two Aviano 6 FS rated at 150Watts each where the total power input of the AVR is around 460 Watts.
However if we are playing movies in 5 channel then also 5x90 Watts ~ 450 Watts closely matches the input power of 460 Watts. So it appears that for most 5.1 playbacks which is 80-85% of what movies come in, the amp is going to do fine.
However when things move to 7 channel then the two additional surrounds should not be ideally running like the two fronts at all the time, only occasionally. Someone who have heard 7.1 movies a lot can elaborate here, I do not of course have a first hand experience until date. So the rear surrounds being driven at 90 Watts should not be happening in any movies even for explosions scenes, since in most of those scenes the explosion if happening on-screen is channeled loud from the fronts and with less probability to be channeled from the surrounds at the same loudness and if that is happening not on the active scene in the screen (happening in the background) then I guess even if they come from the rears it will be less louder. At least this is what my experience with most movies in halls say although I doubt how many of them were 7 channel.
Others, please comment, most of the above are my personal extrapolation from online reviews.
3D Receivers shoot-out: Denon AVR-1911, Pioneer VSX-1020-K, Onkyo TX-SR608 | HyperSensory.com
Go to the very end and check what the site admin has posted as response to a comment, I am quoting it below
While one receiver may be rated at 90watt and another at 110watt, some assume that the rating assumes all channels driven. This is not true, which is of course misleading. Yet, there is almost never a case when all channels need to be driven at full power. No movie or especially music track (as most of them are done in stereo) try to drive speakers at full power on all channels. And no one would listen to such material at full volume either. This fact makes the ratings almost meaningless. In truth, there is only one reason to have those ratings - to ensure that when you buy speakers or receiver, you are able to drive the speakers to a desired volume level without risking damaging speakers or equipment. I have a new 7.1 90watt Denon and some pretty decent full tower speakers rated at 250watt MAX. Yet, I have never needed to turn the volume knob more than 2/3 of the way. It just gets ridiculously loud after that. Of course this also depends on your speaker efficiency, but still - for most installations a 90watt receiver will drive a full set of speakers at desired volume without clipping or going into protection mode (given enough air-flow and following installation recommendations).
So if I am listening to music only in 2 channel mode then 90 watts per channel is fine to drive two Aviano 6 FS rated at 150Watts each where the total power input of the AVR is around 460 Watts.
However if we are playing movies in 5 channel then also 5x90 Watts ~ 450 Watts closely matches the input power of 460 Watts. So it appears that for most 5.1 playbacks which is 80-85% of what movies come in, the amp is going to do fine.
However when things move to 7 channel then the two additional surrounds should not be ideally running like the two fronts at all the time, only occasionally. Someone who have heard 7.1 movies a lot can elaborate here, I do not of course have a first hand experience until date. So the rear surrounds being driven at 90 Watts should not be happening in any movies even for explosions scenes, since in most of those scenes the explosion if happening on-screen is channeled loud from the fronts and with less probability to be channeled from the surrounds at the same loudness and if that is happening not on the active scene in the screen (happening in the background) then I guess even if they come from the rears it will be less louder. At least this is what my experience with most movies in halls say although I doubt how many of them were 7 channel.
Others, please comment, most of the above are my personal extrapolation from online reviews.
dragonxwas
New Member
@_@
Mr.Asit, You might be a older member here, but you must also know that as a new member, I don't know the level of the people here.. So tried to explain what they could understand, It was not meant for you...
Also don't you agree that just getting impedance matched is the safest bet rather than going wattage matching ?
Secondly, I am not a troll posting here..I know what a clip is...But does the other non physics hi-fi enthusiast understand your sin cos and half cut ac waveform ?
also let me quote this :
do you get it ?
Mr.Asit, You might be a older member here, but you must also know that as a new member, I don't know the level of the people here.. So tried to explain what they could understand, It was not meant for you...
Also don't you agree that just getting impedance matched is the safest bet rather than going wattage matching ?
Secondly, I am not a troll posting here..I know what a clip is...But does the other non physics hi-fi enthusiast understand your sin cos and half cut ac waveform ?
also let me quote this :
do you get it ?
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