The best way for normal "standard" stereo amplifiers with normal 'standard' speakers is to not have attenuation on the output signal to speakers as other have said. Control the input signal level and leave the power amplifier output to transductor dynamics alone.

 

The best way for normal "standard" stereo amplifiers with normal 'standard' speakers is to not have attenuation on the output signal to speakers as other have said. Control the input signal level and leave the power amplifier output to transductor dynamics alone.

If the extension speakers are located in an upstairs room and the amplifier is downstairs, then to adjust the volume of the extension speakers one must run downstairs to the volume control of the amplifier.

 

If the extension speakers are located in an upstairs room and the amplifier is downstairs, then to adjust the volume of the extension speakers one must run downstairs to the volume control of the amplifier.

Sure you could add speaker side volume controls but balanced line-level audio signal distribution with local amplification is likely better for homes of you have higher power Hi-Fi systems. If it's just muzak background it won't matter.

 

Sure you could add speaker side volume controls but balanced line-level audio signal distribution with local amplification is likely better for homes of you have higher power Hi-Fi systems. If it's just muzak background it won't matter.

Or use an L-Pad if you’re willing to accept the affect on the audio. Most people can’t notice the difference and that’s why professional multi-room installations use L-Pads. I had a relative worth several millions. He hired an audio company and they wired his mansion with L-Pads.

 

Or use an L-Pad if you’re willing to accept the affect on the audio. Most people can’t notice the difference and that’s why professional multi-room installations use L-Pads. I had a relative worth several millions. He hired an audio company and they wired his mansion with L-Pads.

A LPad changes the transfer function of the crossover and damping factors. If it's a wall 6x9 speaker you're unlikely to notice the difference but that can make a good speaker amplifier pair sound worse. My mansion would never use L-Pads outside of a broom closet.

 

A LPad changes the transfer function of the crossover and damping factors. If it's a wall 6x9 speaker you're unlikely to notice the difference but that can make a good speaker amplifier pair sound worse. My mansion would never use L-Pads outside of a broom closet.

Follow the principle of good enough. My former b-in-law was tone deaf. His 3rd wife was spending enough of his money. So he saved on this.

 

A 6x9 car speaker in a wall will probably resonate at about 80Hz. Then with an L-pad blocking the good damping factor of the amplifier, its one-note-bass will be thought to be good bass by tone deaf people.

 

The goal of my design is to keep distortion to a minimum, and thus I avoided one with transformers.

Resistors affect the damping factor (and thus the speaker resonance), and the crossover frequency of speaker crossover networks, so may not be your best choice for "minimum distortion".
For example these autotransformer attenuators have less the 1% distortion at rated power, and don't significantly affect the amplifier damping factor.

 

Resistors affect the damping factor (and thus the speaker resonance), and the crossover frequency of speaker crossover networks, so may not be your best choice for "minimum distortion".

A transformer produces even greater distortion, doesn't it, especially in commercial volume controls where the transformer must be small enough for the control to fit into a wall box? The transistor replaced the vacuum tube in audio amplifiers partly because the transistor amplifier didn't require the output stage transformer of the tube amp.

 

Cheap transformers used in store speakers' background music or paging systems produce limited frequency response and lots of distortion but nobody cares that it is not hifi.

Actually, my local shopping mall installed very good sounding speakers in its hallways, not the usual cheap crap.
But of course each speaker does not have its own level control, instead just an above average quality transfomer set to maybe 2W. The amplifier for all the mall speakers is probably 600W then it does not need a 70V output transformer.

 

A transformer produces even greater distortion, doesn't it

Not necessarily.
Did you look at the device I referenced?

The transistor replaced the vacuum tube in audio amplifiers partly because the transistor amplifier didn't require the output stage transformer of the tube amp.

The reason was primarily the high cost of quality audio transformers, not that they couldn't deliver low distortion sound (see Mcintosh amps).

 

59 years ago my Heathkit hifi vacuum tubes amplifier sounded good but at the Mcintosh amplifier clinic the measured distortion was awful until I replaced the output tubes every 3 months. 2 years later I sold it to an old geezer and replace it with a solid state receiver that produced low distortion I could not hear. The receiver still works today but a selector switch has worn out.

Many or most people can hear and do not like 1% distortion because it is not clear and is not hifi.
An LM3886 stereo power amplifier IC has no output transformer and a graph in its datasheet shows it producing only 0.002% distortion at 1kHz into 8 ohms at 60W per stereo channel. The distortion is not heard.

 

Not necessarily.
Did you look at the device I referenced?
The reason was primarily the high cost of quality audio transformers, not that they couldn't deliver low distortion sound (see Mcintosh amps).

The attenuators that you provide a link to are described as constant voltage attenuators. Does that mean that they are intended for 70.7V systems? If so, I wonder if the higher voltage would make it easier and/ or cheaper to produce a transformer with less distortion and better frequency response compared to working in a lower voltage range.

 

The attenuators that you provide a link to are described as constant voltage attenuators. Does that mean that they are intended for 70.7V systems?

That just means they normally operate with a constant volume (voltage) level from the amplifier and the attenuator is used to control the speaker volume.
It makes no mention of 70.7V so I don't think it's for that.

I wonder if the higher voltage would make it easier and/ or cheaper to produce a transformer with less distortion and better frequency response compared to working in a lower voltage range.

Not particularly.
A higher voltage just means the wire to the amp can be of smaller gauge for the same power rating.
It would have little effect on the transformer response, since to accommodate a higher voltage, you just use more wire turns on the transformer core for a given sized core.

Another advantage of a transformer attenuator is that it presets a higher impedance load to the amp when operated at lower power levels, which a resistive divider does not.
Thus, for example, if the attenuator is set for the quarter-power point, then the impedance seen by the amp is four times the speaker impedance.
This helps to keep the impedance load seen by the amp above its minimum rating if multiple speakers are connected to the amp.

 

That just means they normally operate with a constant volume (voltage) level from the amplifier and the attenuator is used to control the speaker volume.
It makes no mention of 70.7V so I don't think it's for that.
Not particularly.

Take a look at what is written concerning application of the attenuator.

 

Take a look at what is written concerning application of the attenuator.

Okay.
I saw nothing unusual.
Is there something particular you want me to take note of?

 

Okay.
I saw nothing unusual.
Is there something particular you want me to take note of?

The application section refers to "constant-voltage speakers" the volume of which might need to be independently adjusted. The types of installations that they suggest might make use of the volume control include restaurants, hotels and motels, and retail environments. Those types of installations usually include a large number of ceiling speakers which would call for a constant voltage or 70.7V type of installation.

Dennis Bohn of Rane Corp., in a Rane Note titled "Constant-Voltage Audio Distribution Systems:: 25, 70.7 & 100 Volts", writes that "Constant voltage is a common name given to" the practice of making output of power amplifiers high voltage/ low current to minimize losses in the wiring. That is, the wiring from the amplifier to the speakers can be a smaller gauge with current squared times resistance of the connecting wire not being excessive.

 

I still don't think those reference controls are for 70.7V systems, since they make no mention of that.
A standard audio can be made "constant voltage" which just means that the output power is set at a fixed value and is not changed to control speaker volume.

Constant voltage is rather a misnomer since the voltage varies with the audio signal.
It's just that the volume setting of the amp does not change, and the peak power output voltage is set to 25, 70.7, or 100V depending upon the installation type.

 

I still don't think those reference controls are for 70.7V systems, since they make no mention of that.
A standard audio can be made "constant voltage" which just means that the output power is set at a fixed value and is not changed to control speaker volume.

Constant voltage is rather a misnomer since the voltage varies with the audio signal.
It's just that the volume setting of the amp does not change, and the peak power output voltage is set to 25, 70.7, or 100V depending upon the installation type.

If the peak output voltage is for example 70.7V, then that would destroy a loudspeaker unless it is a constant voltage loudspeaker including a step-down transformer.

 

If the peak output voltage is for example 70.7V, then that would destroy a loudspeaker unless it is a constant voltage loudspeaker including a step-down transformer.

There's no such thing as a "constant-voltage loudspeaker".
Constant voltage systems use standard loudspeakers.
But yes, all 70.7V (or other high voltage) audio systems must have a transformer to reduce the voltage to a standard loudspeaker level.
The transformer may have taps to allow adjustment of the speaker volume.