Which Emotiva amp for stereo listening?

[RichB]

Guys, 4 ohms is not a big deal if the phase angle is small. However, when you get into electrostatics with high reactive components in the impedance, then most AVRs won't do. I rather drive a 4 ohm load with a small phase angle than a 16 ohm load with a large phase angle such as those generated by driving Electrostatics. You need to step out beyond the 4 ohm world now and look at impedance as a whole.

Stereophile show impedance traces and I would like to see more of it.
Often, reviews show low impedance with "moderate" phase angles.

At what point does phase angle become an issue? Is it related to frequency?

Is phase angle a good indicator of a difficult reactive load?

- Rich

 

[AcuDefTechGuy]

I weep for the planet. I staying with my more modest RX300.

- Rich

I don't believe you.

You have a difficult load and a wide face angle. There is no way the RX300 can drive you.

 

[3db]

Stereophile show impedance traces and I would like to see more of it.
Often, reviews show low impedance with "moderate" phase angles.

At what point does phase angle become an issue? Is it related to frequency?

Is phase angle a good indicator of a difficult reactive load?

- Rich

Phase angle is very indicative of how reactive a load is. At 45 degrees, the power is split equally between the reactive and resistive components. Larger than 45 degrees and the load is more reactive then resistive and visa versa for phase angles lower than 45 degrees. Everything is affected by frequency but the effects are much greater in impedance loads where the reactive component is larger than the resistive component.

 

[AcuDefTechGuy]

Guys, 4 ohms is not a big deal if the phase angle is small. However, when you get into electrostatics with high reactive components in the impedance, then most AVRs won't do. I rather drive a 4 ohm load with a small phase angle than a 16 ohm load with a large phase angle such as those generated by driving Electrostatics. You need to step out beyond the 4 ohm world now and look at impedance as a whole.


Here's a link


Generalize Impedance to Expand Ohm’s Law to Capacitors and Inductors - For Dummies

What is considered wide phase angle?

The Klipsch RF83 has phase angle of –56.86 degrees at 74 Hz, min impedance of 3.6 ohms @ 179Hz.

Is that wide?

 

[3db]

What is considered wide phase angle?

The Klipsch RF83 has phase angle of –56.86 degrees at 74 Hz, min impedance of 3.6 ohms @ 179Hz.

Is that wide?

the 45 degree mark is the halfway point between resistance and reactive load.

 

[RichB]

I don't believe you.

You have a difficult load and a wide face angle. There is no way the RX300 can drive you.

I used to let my car drive me but it turned out badly.
After watching this old PSA, I have decided to travel by canoe whenever possible.

[video=youtube;uGu4AwL5Kho]http://www.youtube.com/watch?v=uGu4AwL5Kho[/video]

- Rich

 

[AcuDefTechGuy]

From Stereophile:

As far as our amplifier is concerned, an 8 ohm load with 60° phase angle is considerably more challenging that a 4 ohm load with 0° phase angle.

So I guess a phase angle of 60 degrees or more is considered challenging.

The Klipsch RF83 not only goes down to 3.6 ohms, but it's phase angle is almost 60 degrees. No wonder some AVRs shut down.

 

[RichB]

What is considered wide phase angle?

The Klipsch RF83 has phase angle of –56.86 degrees at 74 Hz, min impedance of 3.6 ohms @ 179Hz.

Is that wide?

the 45 degree mark is the halfway point between resistance and reactive load.

Let me see if I understand:

Does the phase angle increases past 45 degrees the load becomes reactive and therefore more difficult to drive?

- Rich

 

[fuzz092888]

Let me see if I understand:

Does the phase angle increases past 45 degrees the load becomes reactive and therefore more difficult to drive?

- Rich

It's more the combination of low impedance and wide phase angle that really make a speaker difficult to drive. Plus large phase swings won't help either, if my understanding is correct.

 

[cpp]

Let me see if I understand:

Does the phase angle increases past 45 degrees the load becomes reactive and therefore more difficult to drive?

- Rich

nice write up Understanding Impedance Curves & Phase Angles | Audioholics

 

[3db]

Let me see if I understand:

Does the phase angle increases past 45 degrees the load becomes reactive and therefore more difficult to drive?

- Rich

Let me try to explain it this way... If one was driving a purely resitive load, there would be no phase angle regardless of frequency. When one introduces things like capacitors (found in crossovers )and inductors (found in crossovers and the speaker winding itself) a phase angle is introduced.When you place AC across a capacitor, there will be in rush of current in the +ve part of the ac waveform to store charges on the plate of the capacitor. The current starts but it takes time for the charges to build across the plates. Conversely, the same things happen on teh -ve part of the ac waveform. That time difference between applied voltage and the completed charge build across the capacitor plates is measured agianst the period (wavelength) of the ac signal. phase angle. This is for any ac frequency. A phase angle is the angular difference between voltage and current. So for pure capacitor circuits, current leads the voltage by 90 degrees. For pure inductors, current lags the voltage by 90. Start throwing in resistance into the circuits and the the 90 changes. Throw all three components in and it becomes a complex imepdance.

]

I couldn't find one for the inductors and I couldn't hear the audio. I hope they mentioned current leading voltage in this example. It looks like the demonstrated that.

So getting back to your question, the capacitor and inductor values are constant but their impedance changes with the freqeuncy applied to them. I hope this helps.

 

[mister wiggles]

This about sums up how i feel right now.

 

[ImcLoud]

think of it this way, when e=mc bridged to the third square, you can eat pi and drink whiskey while watching the tv show roots... its that easy, linear phase angle and watts law reflect what you hear when you plug your avr into a north facing wall on a rainy october afternoon vs a south west facing wall on a snowy january morning... its basic mathmatics, Im surprised you guys didn't pick up on this sooner...

 

[RichB]

think of it this way, when e=mc bridged to the third square, you can eat pi and drink whiskey while watching the tv show roots... its that easy, linear phase angle and watts law reflect what you hear when you plug your avr into a north facing wall on a rainy october afternoon vs a south west facing wall on a snowy january morning... its basic mathmatics, Im surprised you guys didn't pick up on this sooner...

What Rich hears: blah blah blah whiskey blah blah blah.


My take: the phase angle of the dangle = the torque of the pork.

- Rich

 

[AcuDefTechGuy]

You guys still have given the take-home message: a phase angle of 60 degrees (-60 degrees) is very challenging for an amp to drive.

So if the minimum impedance is < 4 ohms from 100Hz - 10kHz and the phase angle is > 60 degrees, don't use an AVR for the amp.

Challenging for Amps: Impedance < 4 ohms, Phase Angle > 60 degrees. That is the take-home message.

 

[mister wiggles]

You guys still have given the take-home message: a phase angle of 60 degrees (-60 degrees) is very challenging for an amp to drive.

So if the minimum impedance is < 4 ohms from 100Hz - 10kHz and the phase angle is > 60 degrees, don't use an AVR for the amp.

Challenging for Amps: Impedance < 4 ohms, Phase Angle > 60 degrees. That is the take-home message.

assuming i understand what you're saying, what specs can be sought out in the amplification specs to determine whether or not the unit is a good match with the speakers? Are phase angle details published in any of the amp/speaker literatures?

 

[AcuDefTechGuy]

assuming i understand what you're saying, what specs can be sought out in the amplification specs to determine whether or not the unit is a good match with the speakers? Are phase angle details published in any of the amp/speaker literatures?

No, the minimum impedance/frequency & phase angle/frequency will be found on measurements by 3rd parties like HTM/S&V, Stereophile, AH, Soundstage/NRC.

It would be nice if all speaker companies furnish or publish those numbers, but they usually don't.

 

[fuzz092888]

assuming i understand what you're saying, what specs can be sought out in the amplification specs to determine whether or not the unit is a good match with the speakers? Are phase angle details published in any of the amp/speaker literatures?

If the manufacturer provides it, or the speakers were measured by an independent third party, you would look at the impedance graph. This graph should contain both impedance and phase. This is for speakers.

For amplifiers, a rating of 4 ohms usually means the unit will be stable to 2-3 ohms, but definitely not below. You should also look at the power supply, which is the total capacitance and transformer size. Another factor would be if the capacitance is shared by all channels or if each channel has it's own bank.

 

[AcuDefTechGuy]

Here is the Phil3: Philharmonic Audio

At the minimum impedance of ~ 4 ohms, the phase angle is close to 0 degrees.

So the Phil3 does not go below 4 ohms and the phase angle about 0 degrees. That's why my Denon 3312 has no problem driving the Phil3 to extremely loud volume (for me).

The largest phase angle is probably about -60 degrees, but only at about 10 ohms, so no big deal.

If the phase angle were -60 degrees at 4 ohms from 100Hz-5kHz, that would be a challenge for amps.

So the take-home message is to look for 1) the largest phase angle below 8 ohms and 2) the minimum impedance.

A phase angle of 60 degrees @ 8 ohms is more challenging for amps than a phase angle of 0 degree @ 4 ohms.

 

[Irvrobinson]

My take: the phase angle of the dangle = the torque of the pork.

- Rich

That is so profound it makes my head hurt.