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Posts by analogsurviver

Damn - I wrote an answer, forgot to press "submit"  - and unintentionally closed that window... - will repeat tomorrow.
I simply wanted to stress the point that battery manufacturers are not particularly forthcoming with the noise characteristics of their products. As noted in the IEEE link provided a few posts above, it has not been a theme for a LONG period - only when extremely low noise applications are required, there were tests of battery noise against the best PSUs.  I can remember a few AA NiMHs ( Korg MR-1000 recorder uses 8 of these in series ) having tendency to "farting" - out...
Of course it can be done. Now go check ANY battery manufacturer's specs - and see if the noise plot is included ... After finding batteries that do not noise in my applications, I kind of called it quits. Can't test (courtesy of my wallet ) each and every battery on the planet...
It IS like pulling teeth. Very much unfortunately so. Because each and every battery manufacturer is the least likely to supply the data for the inherent noise of the battery. That figure is most likely to be published by some super duper power supply manufacturer - in fact, the first concrete noise rating for battery I have really seen made public this way. And, to make matters worse, they chose about the noisiest battery available at the time for comparison - by now,...
There are ultra low noise solid state power supplies available. The noise of the batteries VARY greatly from type to type - as does its internal impedance. That is why, regardless of all ecological issues, NiCD batteries are still irreplaceable in some applications.  All of the above has to be carefully considered for the exact application - sometimes PSU is superiour, sometimes battery. No clear cut answer to which is better - in practice. It is up to the actual...
The noise of the battery is somewhat higher than that of the finest power supplies - it can be up to approx 6 dB.It is relevant in high gain low voltage input (pre)amplifiers - phono cartridge, microphone ( in that exact order - carts can have outputs as low as 0.04 mV/5cm/sec, which is 0 dB reference level on record - and the signal to noise at this minuscule voltage input  should be at least 60 dB). In theory at least - in practice, getting the isolation from the mains,...
It is *difficult* to get two phono cartridges equal in loudness by referencing their output at 1 kHz ( which is what I usually do ) - and cartridges are FAR more linear than headphones. Depending on the music ( which part of the frequency response is most represented ), it may well turn out that equalling levels at reference  1 kHz may work for some songs better than the others.  There is more to this than just frequency response; the one transducer that is more dynamic...
There IS an exception to this sad state of affairs people listening to the same headphones and each and every one reporting different results ( as it should be - due to the differences in ear size/pinna - as individual as a fingerprint - and with which each individual ear/brain system has learned to hear correctly ). The answer is called AKG K-1000.   anything else involving pads, tips etc is at least one step removed from the natural hearing - and will modify our hearing...
I barely get to use the Amazon - most of the time, they either do not ship to my country at all, in case of free shipping to most other locations, there is a shipping fee ; most others are accompanied by shipping fee that is a definite deal breaker.  Returns - R Y serious !?! But I do have Philips SHP-9500 headphones perched on my head as I type this - and this is my #1 reasonable purchase from Amazon !
Well, I guess that is the safest way ...
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