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In Reply to: RE: connecting audio gears directly to ac without plugs posted by unclestu on April 22, 2015 at 01:40:15
But the problem is that you SHOULDN'T hear a difference, not that you do.
The power line looks horrible on a scope nowadays, way different than it did in the 50's when power factor was the main concern. If your gear isn't designed to reject those signals, and most aren't, then you got problems.
On top of that running unbalanced signals with grounded power cords is just asking for grief. Most of my stuff doesn't have "safety" grounds and that helps somewhat I think.
I've been tinkering with some resonance and Vib. issues of late and was blown away with the actual aural magnitude of the problem which I figured would be minor at worst. Perceptually it turned out to be anything but...
So far I have found little sensitivity to power supply issues but you know how it goes, you get one thing cleaned up a bit and as a reward you then hear the next layer of issues. Guess that's what makes it an 'interesting' hobby...
Regards, Rick
Follow Ups:
I'm finding that power factor correction even though an audio system is on the small scale of things, makes a difference.Even just using the .1 uF caps that are UL approved makes a difference. I initially though it merely shunting off noise, but I was informed by an EE that according to his measurements, it is affecting PF to a certain degree.
One of the things I have noticed is that running the snubbing circuits after the diodes, while making a sonic difference, ignores the spikes reflected back into the power transformer secondaries.
Since I use tubes, it is difficult to shunt the the B+ leads directly. Pondering the the reflection concept, I snubbed the other secondary outputs, namely the filaments (easy since they are low voltage). I was greatly rewarded by a much smoother and fuller sound. I was rather shocked at the amount of change and started to look at power transformers very differently.
Apparently the rectifier spikes go backward ( as was rather obvious) but can seriously contaminate the other secondaries. I have not really studied transformers, but it seems that such noise must be reflected and retained in at least the secondary windings.
We may be fighting more the effects rather than getting at the source of the issues in power transfer.
Of course YMMV and FWIW
Edits: 04/22/15
Hi Stu,
So before bridge and transformer you put a capacitor across + and -?
Did you try a RC across the + and - too?
The good thing in puting capacitor after the transformer is that you play with low voltage and so you can use other types of capacitors than X and Y ones. So you have to get the right value and you can play too around with the capacitor quality wich should be "earable" too. I think about very good and inexpensive russian teflons.
Well after transformer and before bridge. Hard to find high voltage AC caps for tube gear, so I place the caps, standard 120 VAC on the lower voltage secondaries like the heater taps. I make a bridge of .1 uF AC caps across both legs and ground.
works extremely well:eliminates high frequency edginess and brings out the midrange, lowering sn ratio and increasing dynamics. Oh and adds more detail
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