Should I Bi Amp or use a separate amp??

kliewerville

Hey Guys.....so i recently bought a new receiver pioneer vsx934 but it pushes about half the power my old yamaha pushed.....ive never needed an amp but am looking into 1. Now my towers are 8ohm and bookshelfs are 6 ohm in which this reciever pushes twice as much on 6 ohm so all i need ampd is my towers. Can i run the amp to one set of plugs on my Signature S55's and the other set just to my reciever? Trying to figure out exactly what i need to get to make this thing atleast get 150w p front channel. Thanks.

mhardy6647

so, let's see... where to start?

1) 'half the power' = 3 dB less.
2) 'twice as much on 6 ohm' ? Really? It's not impossible (i.e., if the amplifier is 'downrated' in terms of its power output into an 8 ohm load vs a 6 ohm load) but it's not likely.
3) 'pushes'?


If you want 'at least 150 watts* p front channel' -- I think you're gonna want a 150 watt per channel amplifier.

More to the point, I suppose -- what are you trying to achieve and why do you think "150 watts" per channel is what you need to achieve it?

____________________
* Speaking of watts -- do you understand the interrelationship between voltage, current, power, and impedance? If you don't, do a little reading on Ohm's Law.



This is really important because it helps explain why, when it comes to transducing electrical watts of power into acoustic watts of power (or dB of sound pressure level, which is a related but not identical quantity of "loudness"), a basic knowledge of Ohm's Law in its permutations (as shown on the 'wheel' above) illustrates that there's no such thing as a free lunch.

For example 2.83 volts into a nominal 8 ohm load is one watt of electrical power. 2.83 volts into a nominal 4 ohm load is two watts of electrical power. The difference? Twice as much current has to flow through a four-ohm load compared to an eight-ohm load. If a given amplifier cannot deliver the amount of current needed into a low impedance load compared to a higher impedance load, it cannot deliver the expected amount of power into the lower impedance load.

mhardy6647

So, according to Crutchfield, the sensitivity of the S55 speaker is 90 dB SPL @ 1 meter with 2.83 volts of signal input, and the nominal impedance is 8 ohms. The actual impedance varies as a function of the frequency of the signal being amplified and transduced... but "on the average", at least, Polk claims it is an 8 ohm load.

What does this mean?

2.83 volts into 8 ohms is 1 watt.
If you feed a signal at 1 watt of power into one of these speakers and measure the sound pressure level 1 meter from the speaker, the SPL is supposed to be 90 dB. That is pretty darned loud. OSHA permissible exposure limit to 90 dB SPL is 8 hours.
https://www.etymotic.com/downloads/dl/file/id/47/product/307/noise_exposure_explanation_of_osha_and_niosh_safe_exposure_limits_and_the_importance_of_noise_dosimetry.pdf

Move to two meters away, and the SPL drops to 87 dB; four meters, 83 dB, etc.

If you feed 150 watts of signal into the speaker, and measure SPL 1 meter away, it "should" be (nominally) 111.8 dB. This is dangerously loud, with an OSHA permissible exposure limit of less than 15 minutes per day. More than that will, sooner or later, cause irreversible hearing damage.

As an aside: If you have two speakers (stereo), the SPL will increase by 3 dB, because there are 2 total watts going into the 2 speakers and being transduced into sound. 93 dB 1 meter away.

So... it's not really all quite this simple (because the signal of music waveforms isn't at all simple, and amplifiers aren't at all perfect, nor are loudspeakers... and the room environment 'counts', too), but these are sort of the stakes in the sand when it comes to power, impedance, and SPL for these speakers.

kliewerville

Wow alot of info. Thanks for taking that time....much appreciated!!

audioluvr

mhardy6647 wrote: »

so, let's see... where to start?

1) 'half the power' = 3 dB less.
2) 'twice as much on 6 ohm' ? Really? It's not impossible (i.e., if the amplifier is 'downrated' in terms of its power output into an 8 ohm load vs a 6 ohm load) but it's not likely.
3) 'pushes'?


If you want 'at least 150 watts* p front channel' -- I think you're gonna want a 150 watt per channel amplifier.

More to the point, I suppose -- what are you trying to achieve and why do you think "150 watts" per channel is what you need to achieve it?

____________________
* Speaking of watts -- do you understand the interrelationship between voltage, current, power, and impedance? If you don't, do a little reading on Ohm's Law.



This is really important because it helps explain why, when it comes to transducing electrical watts of power into acoustic watts of power (or dB of sound pressure level, which is a related but not identical quantity of "loudness"), a basic knowledge of Ohm's Law in its permutations (as shown on the 'wheel' above) illustrates that there's no such thing as a free lunch.

For example 2.83 volts into a nominal 8 ohm load is one watt of electrical power. 2.83 volts into a nominal 4 ohm load is two watts of electrical power. The difference? Twice as much current has to flow through a four-ohm load compared to an eight-ohm load. If a given amplifier cannot deliver the amount of current needed into a low impedance load compared to a higher impedance load, it cannot deliver the expected amount of power into the lower impedance load.

mhardy6647 wrote: »

So, according to Crutchfield, the sensitivity of the S55 speaker is 90 dB SPL @ 1 meter with 2.83 volts of signal input, and the nominal impedance is 8 ohms. The actual impedance varies as a function of the frequency of the signal being amplified and transduced... but "on the average", at least, Polk claims it is an 8 ohm load.

What does this mean?

2.83 volts into 8 ohms is 1 watt.
If you feed a signal at 1 watt of power into one of these speakers and measure the sound pressure level 1 meter from the speaker, the SPL is supposed to be 90 dB. That is pretty darned loud. OSHA permissible exposure limit to 90 dB SPL is 8 hours.
https://www.etymotic.com/downloads/dl/file/id/47/product/307/noise_exposure_explanation_of_osha_and_niosh_safe_exposure_limits_and_the_importance_of_noise_dosimetry.pdf

Move to two meters away, and the SPL drops to 87 dB; four meters, 83 dB, etc.

If you feed 150 watts of signal into the speaker, and measure SPL 1 meter away, it "should" be (nominally) 111.8 dB. This is dangerously loud, with an OSHA permissible exposure limit of less than 15 minutes per day. More than that will, sooner or later, cause irreversible hearing damage.

As an aside: If you have two speakers (stereo), the SPL will increase by 3 dB, because there are 2 total watts going into the 2 speakers and being transduced into sound. 93 dB 1 meter away.

So... it's not really all quite this simple (because the signal of music waveforms isn't at all simple, and amplifiers aren't at all perfect, nor are loudspeakers... and the room environment 'counts', too), but these are sort of the stakes in the sand when it comes to power, impedance, and SPL for these speakers.

There you go. Clear as mud

ken brydson

mhardy6647 wrote: »

So, according to Crutchfield, the sensitivity of the S55 speaker is 90 dB SPL @ 1 meter with 2.83 volts of signal input, and the nominal impedance is 8 ohms. The actual impedance varies as a function of the frequency of the signal being amplified and transduced... but "on the average", at least, Polk claims it is an 8 ohm load.

What does this mean?

2.83 volts into 8 ohms is 1 watt.
If you feed a signal at 1 watt of power into one of these speakers and measure the sound pressure level 1 meter from the speaker, the SPL is supposed to be 90 dB. That is pretty darned loud. OSHA permissible exposure limit to 90 dB SPL is 8 hours.
https://www.etymotic.com/downloads/dl/file/id/47/product/307/noise_exposure_explanation_of_osha_and_niosh_safe_exposure_limits_and_the_importance_of_noise_dosimetry.pdf

Move to two meters away, and the SPL drops to 87 dB; four meters, 83 dB, etc.

If you feed 150 watts of signal into the speaker, and measure SPL 1 meter away, it "should" be (nominally) 111.8 dB. This is dangerously loud, with an OSHA permissible exposure limit of less than 15 minutes per day. More than that will, sooner or later, cause irreversible hearing damage.

As an aside: If you have two speakers (stereo), the SPL will increase by 3 dB, because there are 2 total watts going into the 2 speakers and being transduced into sound. 93 dB 1 meter away.

So... it's not really all quite this simple (because the signal of music waveforms isn't at all simple, and amplifiers aren't at all perfect, nor are loudspeakers... and the room environment 'counts', too), but these are sort of the stakes in the sand when it comes to power, impedance, and SPL for these speakers.

mhardy6647

I think a lot of expensive hifi products would be far less successful for their manufacturers if more folks knew Ohm's Law.

BlueFox

mhardy6647 wrote: »

.....if more folks knew Ohm's Law.

I agree. Ohm’s law is only relevant for DC circuits.

kliewerville

Kinda lol

mhardy6647

BlueFox wrote: »

mhardy6647 wrote: »

.....if more folks knew Ohm's Law.

I agree. Ohm’s law is only relevant for DC circuits.

That is not correct.
Ohm's law applies to AC as well; resistance is replaced by impedance.
If 'we' treat impedance as a constant, all of the above is true as written. .. but of course impedance ain't constant, so it ain't (as I said).

Now, impedance is a complex quantity since it consists of resitance, capacitive reactance and inductive reactance... and that stuff is all really important, too -- and
part of why Amplifier A and Amplifier B may -- ahem -- push the same number of watts, but not perform identically into the same load.

Viking64

https://www.youtube.com/watch?v=sTss9K0LXJ0

BlueFox

mhardy6647 wrote: »

BlueFox wrote: »

mhardy6647 wrote: »

.....if more folks knew Ohm's Law.

I agree. Ohm’s law is only relevant for DC circuits.

That is not correct.
Ohm's law applies to AC as well; resistance is replaced by impedance.
If 'we' treat impedance as a constant, all of the above is true as written. .. but of course impedance ain't constant, so it ain't (as I said).

Now, impedance is a complex quantity since it consists of resitance, capacitive reactance and inductive reactance... and that stuff is all really important, too -- and
part of why Amplifier A and Amplifier B may -- ahem -- push the same number of watts, but not perform identically into the same load.

Thanks for proving my point.

aprazer402

https://www.youtube.com/watch?v=iNVgP0EUI9Q

What's the current, the current, the current, I want the current.

mhardy6647

BlueFox wrote: »

mhardy6647 wrote: »

BlueFox wrote: »

mhardy6647 wrote: »

.....if more folks knew Ohm's Law.

I agree. Ohm’s law is only relevant for DC circuits.

That is not correct.
Ohm's law applies to AC as well; resistance is replaced by impedance.
If 'we' treat impedance as a constant, all of the above is true as written. .. but of course impedance ain't constant, so it ain't (as I said).

Now, impedance is a complex quantity since it consists of resitance, capacitive reactance and inductive reactance... and that stuff is all really important, too -- and
part of why Amplifier A and Amplifier B may -- ahem -- push the same number of watts, but not perform identically into the same load.

Thanks for proving my point.

Any time -- it's still all 100% true, complete and correct, for any given value of "Z". I mean, that's how amplifier designers... design.