How about an experiment instead of the endless hand-waving. Use two separate power supplies for the two channels, first with just the electrolytics in each, then with the bypass caps added to each. If no difference detected, then something is feeding thru the common B+ earlier.
If so, then back to the original single supply setup with the bypass cap in place and put a sensitive current probe on it to see what it is shunting out.
Could also try the two separate supply case, but connect them in parallel using grounds and the bypass cap bridged across the B+s and see what crosses the cap (current probe again and also listening test). Could put a headphone across the cross/bypass cap and VERY carefully try to listen to it (use a 1:1 interstage xfmr for isolation, otherwise the headphones will be floating at B+!!!!!) Or a differential V scope probe across the cross/bypass cap.
Have to make sure the two B+s are exactly matched DC wise at idle.
If so, then back to the original single supply setup with the bypass cap in place and put a sensitive current probe on it to see what it is shunting out.
Could also try the two separate supply case, but connect them in parallel using grounds and the bypass cap bridged across the B+s and see what crosses the cap (current probe again and also listening test). Could put a headphone across the cross/bypass cap and VERY carefully try to listen to it (use a 1:1 interstage xfmr for isolation, otherwise the headphones will be floating at B+!!!!!) Or a differential V scope probe across the cross/bypass cap.
Have to make sure the two B+s are exactly matched DC wise at idle.
Last edited:
I think you hit it right on. The headphones are a non-directional source since they are stuck to the sides of our head. So to create a sense of directionality with the balance control the amplitude of one side has to be raised or lowered. That has nothing to do with timing or phase shifting. The change in signal to create any noticable affect is going to be easily scopeable.
So to affect a noticable difference in sound using a reverb for some change in spaciality, what is the smallest delay time that could be used to create the ''echo" necessary for a hall affect as opposed to a dead studio affect? The distance to and from a wall for the echo effect has to be many feet and therefore a relatively large fraction of a second. Not Khz times.
Last edited:
Isn't it quite an intellectual leap we've got going here?
Anatoliy, you got a lot of 'splainin to do...
How about measuring current through the bypass cap at audio frequencies whilst playing program material? There must be a stepwise approach to eliminate at least a few more variables and zero in on a defensible explanation.
Not saying you're wrong at all, just that there is a lot of ground to cover yet to build a convincing case.
Cheers!
Michael
LOL I see Don's there already!!!
Anatoliy, you got a lot of 'splainin to do...
How about measuring current through the bypass cap at audio frequencies whilst playing program material? There must be a stepwise approach to eliminate at least a few more variables and zero in on a defensible explanation.
Not saying you're wrong at all, just that there is a lot of ground to cover yet to build a convincing case.
Cheers!
Michael
LOL I see Don's there already!!!
Maybe the next time I'm designing an amp that needs over 800v and PS filter caps placed in series, without equalizing resistors, I might worry about this.
It's just an experiment, I wouldn't leave the B+s cross connected permanently. (besides, that would likely collapse the stereo field) The matched DC voltages were for the benefit of the differential V probe test (or the inter-stage xfmr/headphone test). The whole point of which is to narrow down what's going on so that more specific/focused measurements can be made. Hopefully, once the phenomenon is understood, simpler testing can be done while constructing any amplifier to clear up any stereo imaging problem.
If two B+ xfmrs are not available, could try splitting the B+ using two inductors (or even just some resistors) to two electrolytics to ground (the usual dual split setup). Then experiment with the bypass cap shunts across them or bridged between them.
If two B+ xfmrs are not available, could try splitting the B+ using two inductors (or even just some resistors) to two electrolytics to ground (the usual dual split setup). Then experiment with the bypass cap shunts across them or bridged between them.
Last edited:
You can be as contentious as you want.
Who were the other professional engineers who were witness to his tests?
From long experience in electronics, if you can't explain how something is behaving it is because you haven't asked the right question. The frequent lack of quality (and expensive) test equipment in VT audio /DIY virtually assures that few questions or good measurements get made. Hence the endless try this part ... try that part.
Having done some measurements on some of the low cost OTs being made, for example, I have been amazed they could stay in business, but no one ever really checks quality apparently. (You wonder why there are so few specs posted on OTs?) I've seen OTs that have half the bandwidth on one primary side versus the other. SE ones designed for 20 Kilogauss Max flux (you could pull the core out, it would be only air equivalent from saturation). Loosely wound Audiophile caps that mechanically resonate. On and on....
The burden in this field is now on the manufacturers as to whether ANY of there stuff works in my opinion. Test and verify or forever buy expensive junk.
Having done some measurements on some of the low cost OTs being made, for example, I have been amazed they could stay in business, but no one ever really checks quality apparently. (You wonder why there are so few specs posted on OTs?) I've seen OTs that have half the bandwidth on one primary side versus the other. SE ones designed for 20 Kilogauss Max flux (you could pull the core out, it would be only air equivalent from saturation). Loosely wound Audiophile caps that mechanically resonate. On and on....
The burden in this field is now on the manufacturers as to whether ANY of there stuff works in my opinion. Test and verify or forever buy expensive junk.
Last edited:
I have no idea where is your hair, but I've found that electrolytics are not bad at all, they don't need to be replaced by batteries of motor run or other audiophoolery caps; and bypassing is not needed for high frequency response, but for minimizing non-linear capacitance effects. I wish non-linearities of tubes could be minimized similarly, by bypassing of fat powerful tubes by smaller ones.
Hmmm... Maybe you can bypass the big tubs with small ones. Have you tried it?
Hmmm... Maybe you can bypass the big tubs with small ones. Have you tried it?
Yes, I got some idea when sleeping last night. Not to bypass exactly, but something very similar.
hello.
.....so it looks like many audiophiles paralell plastic caps (0,1uf..........up to xx uf ) to the electrolytics...........
did somebody try this out with small electrolytics (low esr type and so on...)?
i did it with 10uf elyts' or so in my solid state amps and chip amps psu...........and sometimes i prefer it (sonically) over the plastic caps.
.....so it looks like many audiophiles paralell plastic caps (0,1uf..........up to xx uf ) to the electrolytics...........
did somebody try this out with small electrolytics (low esr type and so on...)?
i did it with 10uf elyts' or so in my solid state amps and chip amps psu...........and sometimes i prefer it (sonically) over the plastic caps.
Last edited:
I am going to experiment later: take couple of caps and couple of resistors, make a bridge with equal time constants, and see what is in diagonal of it, when applied bias & AC.
But I am pretty sure already it is non-linear capacitance that causes phase inter-modulation that affects stereo image only.
But I am pretty sure already it is non-linear capacitance that causes phase inter-modulation that affects stereo image only.
Wave,
How could a PS characteristic that is common and identical to both channels create a difference between the channels that would present itself as channel seperation to create "more real" imaging?
I guess, the lower and more linear is dynamic resistance of PS, the less of intermodulations happen.
It might also be good to try to determine if there are differences in phase-angle shift versus frequency, from input to output, between the two setups. Things like square waves depend not only on the amplitude relationships of the harmonics, but also on the phase relationships. So if the phase-angle shifts differently for different frequencies, it could "blur" or otherwise deform or re-shape any fast-rising edges or abrupt changes in amplitude, and would affect other types of waveforms too. You might even be able to relatively-quickly see if anything like that is happening, by comparing square wave edges and corners, in the time domain, between the two setups.
There I was, calmly reading this thread, when I discovered that my powers are now so great that I can contribute without even saying anything!
I think what I probably actually said, in a different context on another thread, is that an ideal capacitor is a linear device (as some seemed to be denying that). A real capacitor is a reasonable approximation to a linear device (unless it is an electrolytic, or polyester, or hand-made by Patagonian virgins during a full moon).
Some people like to bypass their electrolytics, others don't; I don't know which is best. Some bypass everything in sight, which seems unnecessary. If I had something useful to say beyond that I would say it.
to reiterate what I said in a thread on capacitors, which DF96 also debated, ideal caps are linear, but "real-life" caps are not quite linear due to effects contributed by ESR and ESL and dielectric absorption. (of which I believe Electrolytic caps suffer the most dielectric absorption). Hence bypassing with some value of "very low-ESR, very low-ESL, and very low-absorption" capacitor should help overcome those effects slightly. choice of caps depends on your budget and preferences, and this is actually where all the debate is. some like film, some foil, some motor runs, etc...to each his own I guess...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.