Watts vs. Clipping!!

[timoteo]

I am running a pair of B&W 683s as my mains in my 6.2 setup. They are being powered by my Denon AVR-889 which is 7.1 100wpc. My 683s are rated at 200w.

My question is will i lessen the chance of clipping if i bi-amp the 683s compared to just bi-wiring them as i am now?
Then i would be sending 200w to them compared to 100w.

I have tried bi-amping them b4 but did not hear a difference & wanted my 6th channel back.
When i watch movies I normally have the master volume at 0db with my mains set to -5db in the reciever.

At these volumes am i even risking clippage?

BTW: i have just the mains set to large...no need to comment on the whole small vs large thing, im discussing that in another thread!

 

[Wannabubble]

By biamping your speakers with just the receiver, you will not notice any difference. For starters, since you are using extra channels from the receiver, they must draw power from a source. What you are doing is taking power from your speakers and putting it right back into your speakers. Essentially instead of sending "100 watts" to your speaker by one cable; ie 1x100, you are sending "100 watts" to your speaker by 2 cables; ie 2x50 (these numbers may not be exact but you get the point)

The reason I say "100 watts" is because your receiver is probably not sending 100 true watts.

The only time you may hear a difference by "biamping" (and you are not truly biamping. You would need 2 amps with separate power supplys to truly biamp) is at lower volume levels. The reason for this is the power supply of the receiver is not being pushed very hard and can create the extra power.

Also since your speakers utilize a passive crossover, I dont think you would be able to notice a huge difference by biamping.

When i watch movies I normally have the master volume at 0db with my mains set to -5db in the reciever.

0db!!!! Do your ears bleed when you are watching a movie?!?!

I would think that is very close to clipping level. I rarely turn mine past -15db unless I am trying to blow my guests' ears out.

 

[timoteo]

no ear bleeds

Actually on my Denon avr889 when i have the master at 0db its pretty stinkin loud but not outrageous. Remember, the calibration set the db levels per channel kinda low...-5.5 for my mains & non over +1.5db. My reciever is only 100wpc.

How much power per channel is ur Denon? What db levels are you channels at?

Plus your Klipsch speakers have a high sensativity so they sound louder than my B&Ws when at the same master db. Ive done a side by side comparison with our two brands.

Boy i sure hope im running my system safely because with the mains at large they sound great!!

 

[TLS Guy]

Actually on my Denon avr889 when i have the master at 0db its pretty stinkin loud but not outrageous. Remember, the calibration set the db levels per channel kinda low...-5.5 for my mains & non over +1.5db. My reciever is only 100wpc.

How much power per channel is ur Denon? What db levels are you channels at?

Plus your Klipsch speakers have a high sensativity so they sound louder than my B&Ws when at the same master db. Ive done a side by side comparison with our two brands.

Boy i sure hope im running my system safely because with the mains at large they sound great!!

The real issue is that if you biamp them, you will not be sending 200 watts to the speakers, but about 101 watts. The reason, is that the amp connected to the high pass filter will only supply the tweeter which takes very little power. As with biwiring this is also a waste of time and resources.

 

[highfigh]

I am running a pair of B&W 683s as my mains in my 6.2 setup. They are being powered by my Denon AVR-889 which is 7.1 100wpc. My 683s are rated at 200w.

My question is will i lessen the chance of clipping if i bi-amp the 683s compared to just bi-wiring them as i am now?
Then i would be sending 200w to them compared to 100w.

I have tried bi-amping them b4 but did not hear a difference & wanted my 6th channel back.
When i watch movies I normally have the master volume at 0db with my mains set to -5db in the reciever.

At these volumes am i even risking clippage?

BTW: i have just the mains set to large...no need to comment on the whole small vs large thing, im discussing that in another thread!

Think of clipping as kids jumping on a trampoline in a room with a ceiling. At a certain point, they run out of headroom and when more kids get on the trampoline, they can't go as high because the membrane sags more, but they still run out of headroom when they reach the ceiling. As the demand from more channels increases, the power supply runs out of reserve and while it still puts out 100W/ch, the dynamics can't be reproduced as well as if it was coasting along with a lot of reserve power.

If the sound track is really dynamic, yes, you can be clipping. If you're averaging 1W and the signal has a 30dB peak, your amplifier needs to produce 1000W for that short period and that's not going to happen anytime soon. However, since the clipping happens for a short time, it's not always going to kill your speakers.

 

[PENG]

highfigh summed it up very well. At the -5 level (effectively), whether the amp will clip or not depends on the type of music. I would add that classical music that has short burst of dynamic peaks will not likely cause damage to the tweeters (as highfigh explained) but you may want to avoid music that has frequent peaks that sustain for longer than say fractions of a second. Since you prefer to set the fronts to large, for movies such as LOTR you may want to turn it down to -5 on your master volume.

Obviously if you want to play it safe, add a 2 channel amp just to satisfy the 683s.

 

[njedpx3]

don't biamp --add an external power amp

I am running a pair of B&W 683s as my mains in my 6.2 setup. They are being powered by my Denon AVR-889 which is 7.1 100wpc. My 683s are rated at 200w.

My question is will i lessen the chance of clipping if i bi-amp the 683s compared to just bi-wiring them as i am now?
Then i would be sending 200w to them compared to 100w.

I have tried bi-amping them b4 but did not hear a difference & wanted my 6th channel back.
When i watch movies I normally have the master volume at 0db with my mains set to -5db in the reciever.

At these volumes am i even risking clippage?

BTW: i have just the mains set to large...no need to comment on the whole small vs large thing, im discussing that in another thread!

IF your AVR power is limited, then it will still be limited; at high wolumes with loweffecicny speakers( less than 90 db senstivity) you could possibly clip at high volumes. For example if the total power is 100 watts times seven channels and you reduce by two channels you could possible get 200 watts by biamping. The settings really don't mean a direct power level they are relative; the best measure of power is your dB level with consideration to your speaker's effeciency. It is difficult to tell what -5db translates to in terms of power. If you have a concern the best bet is to get a separate power amp for your front speakers. Emotiva and Behringer make good power amps. This assumes you have pre-outs.

Remember however power is logrithmic to double the sound (3 dB INCREASE) you have to multiply power by a factor of 10. Example 1000 watts produces twice the sound level of 100 watts.

 

[highfigh]

IF your AVR power is limited, then it will still be limited; at high wolumes with loweffecicny speakers( less than 90 db senstivity) you could possibly clip at high volumes. For example if the total power is 100 watts times seven channels and you reduce by two channels you could possible get 200 watts by biamping. The settings really don't mean a direct power level they are relative; the best measure of power is your dB level with consideration to your speaker's effeciency. It is difficult to tell what -5db translates to in terms of power. If you have a concern the best bet is to get a separate power amp for your front speakers. Emotiva and Behringer make good power amps. This assumes you have pre-outs.

Remember however power is logrithmic to double the sound (3 dB INCREASE) you have to multiply power by a factor of 10. Example 1000 watts produces twice the sound level of 100 watts.

3dB is from doubling the power. +/- 10dB is what you get when you increase/decrease the power by 10x. Multiply it again and you gain another 10dB, so you're now at 100x the original power output. You're right about the subjective doubling of intensity but it's because of the 10dB increase.

Assuming a given power level at 0dB, -5dB is 1dB shy of 1/4 the power output. Definitely noticeable.

 

[njedpx3]

thanks for clarification - OP buy a Behringer EP2500

Think of clipping as kids jumping on a trampoline in a room with a ceiling. At a certain point, they run out of headroom and when more kids get on the trampoline, they can't go as high because the membrane sags more, but they still run out of headroom when they reach the ceiling. As the demand from more channels increases, the power supply runs out of reserve and while it still puts out 100W/ch, the dynamics can't be reproduced as well as if it was coasting along with a lot of reserve power.

If the sound track is really dynamic, yes, you can be clipping. If you're averaging 1W and the signal has a 30dB peak, your amplifier needs to produce 1000W for that short period and that's not going to happen anytime soon. However, since the clipping happens for a short time, it's not always going to kill your speakers.

You are correct thanks for clarification; didn't mean to confuse. Amplifier output - It takes 2 times the power from an amp to change the volume 3dB. In other words if an amp is producing 1 watt of power it needs to increase to 2 watts of power to make a 3dB change. This is a ratio of 2:1. By the same token if the amp is producing 50 watts of power it will need to increase to 100 watts to produce a 3dB change. 100 watts would take 200 watts for that same change.

How much power would it take to Increase the SPL 10dB? It will take 10 times the power to increase the SPL by 10dB! In other words, if your amp was producing 50 watts of power you would need to increase it to 500 watts to achieve a 10dB increase. It takes a lot of power to get a small increase in volume.


As said before either -5dB or 0 dB is very loud on most AVRs. -18 dB on my SR8002 measures out at 100 decibels very loud.

I will say again, even with B & W speakers, which are very nice speakers by the way, if OP likes it that loud of loud then he needs an external amp because at 100 watts per channel he must be close to clipping. The 683s are average efficiency at 90dB sensitivity which menas they are fairly power hungry

I would get the following and not worry about it any more. Behringer EP2500 2channel amp that puts out 450 watts per channel into 8 ohms. Only $284 and B &H Photo. http://www.bhphotovideo.com/c/product/280617-REG/Behringer_EP2500_EP2500_2_Channel_Rackmount.html

Then get a medical warranty on you ear drums

Good Luck,

Cypher King

 

[timoteo]

I just got schooled...literally!

Hey thanks guys for the information & clarification on watts & clippage. The last thing i want to do is abuse my system to the point of any damage. I would go out 2morrow literally & get that 2ch power amp except my DenonAVR889 does not have pre-outs. Any other advice on that matter or would i flat out need a new reciever to ad the external amp??
Thanks again highfigh, njedpx3 & peng for your input!

 

[TLS Guy]

Hey thanks guys for the information & clarification on watts & clippage. The last thing i want to do is abuse my system to the point of any damage. I would go out 2morrow literally & get that 2ch power amp except my DenonAVR889 does not have pre-outs. Any other advice on that matter or would i flat out need a new reciever to ad the external amp??
Thanks again highfigh, njedpx3 & peng for your input!

You need a new receiver or a pre pro.

 

[lsiberian]

Hey thanks guys for the information & clarification on watts & clippage. The last thing i want to do is abuse my system to the point of any damage. I would go out 2morrow literally & get that 2ch power amp except my DenonAVR889 does not have pre-outs. Any other advice on that matter or would i flat out need a new reciever to ad the external amp??
Thanks again highfigh, njedpx3 & peng for your input!

This is a fruitless endeavor.

1st when running 2 channel stereo sound most receivers have a little more headroom. 100 watts is likely lower than it can truly deliver for 2 channels based of my own reading of 3rd party receiver reviews for Denon and my experience with receivers.

When running 7 channel you are watching a movie and clipping isn't a big deal usually because they compress the range so much.

 

[highfigh]

This is a fruitless endeavor.

1st when running 2 channel stereo sound most receivers have a little more headroom. 100 watts is likely lower than it can truly deliver for 2 channels based of my own reading of 3rd party receiver reviews for Denon and my experience with receivers.

When running 7 channel you are watching a movie and clipping isn't a big deal usually because they compress the range so much.

Back in the Stone Age (the late 1970s), if a receiver or amp was rated for specific output power according to FTC guidelines, a randomly chosen unit had to meet spec, which included testing with both channels driven, measured from 20Hz-20KHz (or better if the numbers were really good). I remember reading many reviews that showed test results that often exceeded the manufacturer's stated output and this was confirmed by our service department's testing pieces that came through for repair. I don't know if/when the FTC removed its requirement for this but if they did, they should be clubbed.

 

[PENG]

Back in the Stone Age (the late 1970s), if a receiver or amp was rated for specific output power according to FTC guidelines, a randomly chosen unit had to meet spec, which included testing with both channels driven, measured from 20Hz-20KHz (or better if the numbers were really good). I remember reading many reviews that showed test results that often exceeded the manufacturer's stated output and this was confirmed by our service department's testing pieces that came through for repair. I don't know if/when the FTC removed its requirement for this but if they did, they should be clubbed.

Actually depending on which bench test you believe and assuming the 889 is the same as the 2308 (or 2309), he may not be in too bad a shape.

According to http://www.homecinemachoice.com/node/6642

For the 2307

2 channel stereo - 120W 8 ohms 1 kHz, 200W 4 ohms
5 channel - 95W 8 ohms, 135W 4 ohms
Fidelity Firewall at 1 kHZ 2 channel - 125W into 8 ohms, 0.01% THD.

Freq response - 20 to 20,000 Hz +/- 0.1dB

http://www.homecinemachoice.com/node/10515

For the 2309

2 channel stereo - 153W 8 ohms 1 kHz, 0.5% THD 221W, 4 ohms

5 channel - 105W 8 ohms, 96W 4 ohms
Fidelity Firewall at 1 kHZ, 2 channel - 145W into 8 ohms, 0.04% THD.

Freq response - 20 to 20,000 Hz +/- 0.11dB

The 2308 is the model in between so we can reasonably assume it would have yielded similar results.

These are U.K. reviews but if you compare the U.K and N.A. models are basically the same. The thing I like about the H.C.C. reviews is that they include the so called fidelity firewall outputs typically tested at very low THD levels.

At the SPL the OP prefers, the risk of clipping is there but I doubt it will be at the point it would damage the tweeters. The resulting distortion may be audible so sound quality may suffer. Again, for peace of mind and to get the best out of those B&Ws, he needs a new receiver that has preouts, or a prepro, and a power amp. The only other alternative is to turn the master volume down to say around -10 or lower at all times.

 

[timoteo]

New Denon soon!

Well until i can upgrade to something with more power im just gonna have to turn the master down a bit.
One other question i have is concerning the input level.

If i turn the input level up (5db) & turn the master volume down by equal db (5db), will the reciever be working just as hard?

Or by chance will the input level work kind of like opening the doorway for information/power to enter the reciever therefore relieving the reciever of some duty?

Because if this IS the case then i could get the listening level i want & not be pushing my 889 as hard. This is probably wishful thinking but thought i'd ask anyway!!

 

[highfigh]

Well until i can upgrade to something with more power im just gonna have to turn the master down a bit.
One other question i have is concerning the input level.

If i turn the input level up (5db) & turn the master volume down by equal db (5db), will the reciever be working just as hard?

Or by chance will the input level work kind of like opening the doorway for information/power to enter the reciever therefore relieving the reciever of some duty?

Because if this IS the case then i could get the listening level i want & not be pushing my 889 as hard. This is probably wishful thinking but thought i'd ask anyway!!

The only reason any amp or receiver has an input level adjustment is for those pieces of equipment that don't have variable level control and their level needs to be balanced with the others. Amplifiers are made to deliver an amplification differential, relative to the input level. By increasing the level at the front end by 5dB, you risk overdriving that stage and when that happens, it sounds really bad. If it was a tube guitar amp, it's a different story but this stuff is supposed to be set up so the sound is as clean as possible.

You can't very well tow a dump truck uphill with a VW bug and really, power is power. Either the piece doing the work has it, or it doesn't.

 

[NicolasKL]

Well until i can upgrade to something with more power im just gonna have to turn the master down a bit.
One other question i have is concerning the input level.

If i turn the input level up (5db) & turn the master volume down by equal db (5db), will the reciever be working just as hard?

Or by chance will the input level work kind of like opening the doorway for information/power to enter the reciever therefore relieving the reciever of some duty?

Because if this IS the case then i could get the listening level i want & not be pushing my 889 as hard. This is probably wishful thinking but thought i'd ask anyway!!

What do you normally run your volume at? 120 watts is nothing to sneeze at, and is capable of driving your speakers quite loud.

 

[fredk]

At a distance of 10', 100w will get you to 95db with headroom to spare. How big is your room and how far do you sit from the speakers?

 

[JerryLove]

Back in the Stone Age (the late 1970s), if a receiver or amp was rated for specific output power according to FTC guidelines, a randomly chosen unit had to meet spec, which included testing with both channels driven, measured from 20Hz-20KHz (or better if the numbers were really good).

I went and looked this up.

"First, the amplifier under test must be pre-conditioned. This means that it must be run at one-third of its rated power for one hour before the measurements commence. This is a fairly stringent warm-up and insures that whatever is measured is a reasonable long-term value, not something that can only be sustained for a very brief interval under ideal conditions. Beyond this, both channels of a stereo amplifier must be driven simultaneously into a stated load resistance, with the per-channel power being reported. The test is conducted across a stated range of frequencies and total harmonic distortion (THD) measurements are taken throughout. The worst case THD is included. An example specification for a stereo amplifier reads as follows: 100 Watts RMS per channel into 8 Ohms with both channels driven, from 20 Hz to 20 kHz, with no more than .1% THD. Any statement with less information than this is not a legal specification (e.g., an ad stating “100 Watt output per channel” or “100 Watts from 20 Hz to 20 kHz”)."

So, it was only a legal requirement if in specific terminology.

"There is, of course, no such thing as an RMS Watt. RMS is a measurement/calculation technique used to derive power from AC voltages (or currents). The term arises from the fact that modern amplifiers are designed as constant-voltage devices. Thus, output power is determined by measuring the output RMS voltage and then computing the power via V2/R rather than through the use of a Wattmeter. The more accurate wording of “so-many Watts as calculated from the RMS voltage” is far too cumbersome for the average consumer (and quite meaningless as well), so the artificial term “Watts RMS” was born."

So in 2000, the rule was changed; as it was causing problems with things like car audio and self-powered speakers.

 

[timoteo]

My room is 14.5' x 16.5' x 8'.

My AVR is not 120w per but is 100w per.

I sit about 11' to 12' away from my L/C/R and typically have the volume now at about -2db to -5db.

My input level is set at +2db. Im probably going to drop the input down to 0db and if i need to turn the master up a hair i will.

I think that since my B&Ws are pretty power hungry i need to have the volume turned up a little more than other poeople in order to get the same performance. Friends of mine with Klipcsh & Mirage systems have their master volumes a bit lower yet the actual listening volume is about the same as mine.