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In Reply to: RE: Sounds the same ;-) posted by AbeCollins on December 27, 2024 at 07:56:14
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Follow Ups:
My Tektronix scope is stored away in the basement and it's not exactly a modern portable unit ;-)
I did measure with my Fluke True RMS DMM which showed 121-VAC and 60.1 Hz under light load.
This unit isn't particularly expensive. Its also not aimed at audiophiles, who need a nice clean sine wave due to issues with transformer and diode noise generated by a 5th harmonic. If it has noise higher than that it could manifest as a buzz in the midrange or tweeter.
Yes: "Its the waveform you want to see"
Yes: "This unit isn't particularly expensive"
Yes: "Its also not aimed at audiophiles"
As mentioned earlier, I'm not going to haul my hefty Tektronix scope out of the basement storage room to measure a power source that I have no intention of using for the audio setup.
It was just for chits and grins that I hooked it up in the first place ;-). It works. The audio system sounds fine. It's no longer in the setup.
Do you have a phono section? If yes, does it change the noise floor?
If its not obvious, I find this interesting :)
Hmm, that's a thought.
I have a phono preamp I could try. Is this what you had in mind:
- Phono preamp on AC outlet. Crank up the volume with no music playing and listen for noise in the speakers.
- Phono preamp plugged into Jackery power source. Crank up the volume with no music playing and listen for noise in the speakers.
Listen for differences.
I'll try it Wednesday when I get back from the dentist.
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BLUF or "Bottom Line Up Front" please as my boss would say about our written weekly status reports:No difference heard with phono preamp on household AC mains vs the Jackery pure sinewave battery / inverter.
The Jackery pure sinewave battery / inverter is not intended to be an audiophile product. It is normally used to power household appliances when there is no AC mains power - for example, while camping or whenever portable AC power is needed.What we are testing for :
Compare noise level by ear with phono preamp on household AC mains vs Jackery pure sinewave battery / inverter.
Crank the gain way up on the linestage AND way up on the phono preamp, both set to levels orders of magnitude higher than I would ever listen to in real life. With ears right up against a speaker listen while using two different AC power sources to the phono preamp.
The setup :
> My typical normal setting would have the phono preamp gain knob set to 1 O'Clock. For the test I had it locked to the stop fully clockwise at 5 O'Clock.
> My typical normal listening levels would have the linestage gain display set to -40dB to -34dB. For the test I had it cranked way up to -10dB.... which would normally be ear bleed territory.
The results :
The hum / noise is definitely from the phono preamp but there was no difference with it on the AC mains or the pure sinewave battery / inverter . And again, this is with the phono preamp and linestage cranked up dangerously* high and well beyond typical.
For another test I switched the linestage to an unused set of inputs and it was dead silent with it set to the same -10dB whether on household AC mains or the pure sinewave battery / inverter.
Phono preamp on household AC mains
Phono preamp on Jackery pure sinewave battery / inverter
*dangerously high = If music were playing at these levels it would surely fry the speaker coils and burst the cones into shrapnel !!
Conclusion :
The Jackery pure sinewave battery / inverter is sufficiently quiet for powering my audio system even though this is not its main purpose.
P.S. I don't know the exact gain of the phono preamp but it is greater than most. With the Gain knob fully clockwise I can drive a power amp with it directly w/o a linestage. I mention this only to highlight the huge amount of gain in the system.
Equipment in the signal path:
- Dynavector DV-20XH H.O. MC Cartridge
- PS Audio GCPH phono preamp
- Eversolo DMP-A8 Streamer / DAC / Linestage
- NAD C298 stereo amplifier
- Tannoy Definition D500 tower speakers 91dB 6 Ohm nom.
Edits: 01/08/25
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