rythemsandy,
as you can tell now, there is always a lot of scepticism about trying to 'fix' the mains AC going to audio gear, especially when the target for companies such as PS Audio are non-tech audio enthusiasts that gush at the thought of better audio quality from a few well constructed sales-pitch sentences.
Any 'generator' that can regulate to the mains AC voltage (as Elvee indicates) is an option. Most amps then force large rectifying peak currents from the generator supply at the peak of the waveform - which adds distortion to the mains AC voltage that other nearby equipment then experience - and requires a very low impedance source so as to keep the voltage waveform close to sinusoidal.
If you could find a lower source impedance supply, then the waveform would be better, and the rectifying current pulses used in your amp would be even peakier.
If you use a higher impedance supply (eg. a PA amplifier, or a UPS) then your amp will respond with less peaky rectifying pulses, and the mains AC waveform in to your amp will be more distorted.
Harmonics and noise from the mains AC may get in to other windings in your amp that aren't rectified, such as heater wiring for valve amps, or via power grounding and layout within your audio amp. You may be the owner of an audio amp that performs poorly in that regard - such that adding a mains conditioner or filter or regenerator of some kind makes an audible difference - or you may have such a poor mains AC distribution and nearby loads that no normal audio amp can avoid ingress of noise.
All those topics can become hi-tech and detailed very quickly.
as you can tell now, there is always a lot of scepticism about trying to 'fix' the mains AC going to audio gear, especially when the target for companies such as PS Audio are non-tech audio enthusiasts that gush at the thought of better audio quality from a few well constructed sales-pitch sentences.
Any 'generator' that can regulate to the mains AC voltage (as Elvee indicates) is an option. Most amps then force large rectifying peak currents from the generator supply at the peak of the waveform - which adds distortion to the mains AC voltage that other nearby equipment then experience - and requires a very low impedance source so as to keep the voltage waveform close to sinusoidal.
If you could find a lower source impedance supply, then the waveform would be better, and the rectifying current pulses used in your amp would be even peakier.
If you use a higher impedance supply (eg. a PA amplifier, or a UPS) then your amp will respond with less peaky rectifying pulses, and the mains AC waveform in to your amp will be more distorted.
Harmonics and noise from the mains AC may get in to other windings in your amp that aren't rectified, such as heater wiring for valve amps, or via power grounding and layout within your audio amp. You may be the owner of an audio amp that performs poorly in that regard - such that adding a mains conditioner or filter or regenerator of some kind makes an audible difference - or you may have such a poor mains AC distribution and nearby loads that no normal audio amp can avoid ingress of noise.
All those topics can become hi-tech and detailed very quickly.
A flat-top waveform having the same peak value as a sinewave will have a larger rms value, a larger average value, plus a significant harmonic content causing additional noise and vibration in induction motors.
Such a waveform is ~single-purpose: to feed peak-rectified supplies
It is better to charge your reservoir cap for a longer time per cycle to reduce the current.
The larger the reservoir cap is the higher the peak current will be and it will flow over a shorter time. More EMI as the cap gets bigger.
The larger the reservoir cap is the higher the peak current will be and it will flow over a shorter time. More EMI as the cap gets bigger.
It is one of the reasons that led the EU to make PFC compulsory for mains supplies
Putting a power regenerator together
Motivation: After many hours of tuning my speakers and listening to my newly built class A amps I am spoiled. Besides my stereo setup I use a Denon 5803 AVR for TV and such. I noticed that during some days said AVR can sound awful, while in the evening/night it mostly sounds very good. I checked the mains and found a good correlation to high 3rd harmonic content, when the AVR sounds bad. Therefore I want to test, if a regenerator can cure that. Filters and isolation transformers seem not to help with the issue. As the AVR is quite complex with many voltages I refrain from upgrading its supply to the level of my class A amps, which sound always the same.
Test setup: Function generator at 50 Hz --> bridged Luxman M-383 amp @ 70 Volts (78 Volts max) --> fuse --> toroidal step up transformer 230V/2x35V (secondary connected in series) -->AVR
This way I would only have to buy the transformer for 150€ and some connection material to test this. At 30Vac the voltage sags about 0,5V connected to a 6 Ohm load, so 8 Volts headroom should be sufficient. Distortion is on the level of my cheap function generator (0,08% THD). I still have to check the long term voltage stability of my function generator, as this could cause a disaster.
So does this sound like a sound idea (pun intended) or am I missing something?
Many thanks for your comments in advance
Motivation: After many hours of tuning my speakers and listening to my newly built class A amps I am spoiled. Besides my stereo setup I use a Denon 5803 AVR for TV and such. I noticed that during some days said AVR can sound awful, while in the evening/night it mostly sounds very good. I checked the mains and found a good correlation to high 3rd harmonic content, when the AVR sounds bad. Therefore I want to test, if a regenerator can cure that. Filters and isolation transformers seem not to help with the issue. As the AVR is quite complex with many voltages I refrain from upgrading its supply to the level of my class A amps, which sound always the same.
Test setup: Function generator at 50 Hz --> bridged Luxman M-383 amp @ 70 Volts (78 Volts max) --> fuse --> toroidal step up transformer 230V/2x35V (secondary connected in series) -->AVR
This way I would only have to buy the transformer for 150€ and some connection material to test this. At 30Vac the voltage sags about 0,5V connected to a 6 Ohm load, so 8 Volts headroom should be sufficient. Distortion is on the level of my cheap function generator (0,08% THD). I still have to check the long term voltage stability of my function generator, as this could cause a disaster.
So does this sound like a sound idea (pun intended) or am I missing something?
Many thanks for your comments in advance
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Soo I used a smartphone as frequency generator and 1kVA step up transformer from 74 VAC from the amp to 230 VAC. THD was 0,01%. The amps output impedance is 70 mOhm, but with the output transformer the output impedance rises to an awful 2 Ohms.
Result: Thin and a little cleaner sound, that I did not like. I conclude that the step up transformer was a bad idea. 😱
Best regards
Ozo
Result: Thin and a little cleaner sound, that I did not like. I conclude that the step up transformer was a bad idea. 😱
Best regards
Ozo
Ohh well maybe I was a bit quick with judgement....have to compare longtime some more especially when the mains are bad again.....
What I really can recommend is an old smartphone for 20 bucks as function generator with an app like this:
Function Generator – Apps bei Google Play
What I really can recommend is an old smartphone for 20 bucks as function generator with an app like this:
Function Generator – Apps bei Google Play
How did you make the mains measurement?
Perhaps worthwhile trying to make initial observations using only a mains-isolated signal source going to your amp/receiver, to avoid 'hearing' differences that may relate to other signal sources that are mains powered or through some form of mains hum loop.
Mains THD measurement was done with a Keithley 2015 directly plugged into the wall outlet.
Yes it might well be the DAC inside the AVR receiver that is influenced by mains quality. The AVR gets fed a DTS bitstream from a PC via toslink with nothing else connected but the speakers.
Might be worth a try to connect an external signal source, when mains are especially bad again and compare. That way i would know if its the DAC or amp section of the AVR. Although if I remember correctly this AVR performs a ADC on the analog sources anyway.
Right now it sound quite well with the "DIY" regenerator.
Many thanks
Yes it might well be the DAC inside the AVR receiver that is influenced by mains quality. The AVR gets fed a DTS bitstream from a PC via toslink with nothing else connected but the speakers.
Might be worth a try to connect an external signal source, when mains are especially bad again and compare. That way i would know if its the DAC or amp section of the AVR. Although if I remember correctly this AVR performs a ADC on the analog sources anyway.
Right now it sound quite well with the "DIY" regenerator.
Many thanks
