|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
67.189.207.135
In Reply to: RE: is it really that awful ... maybe in spice? posted by Triode_Kingdom on October 12, 2016 at 22:22:40
I guess the question is... "What does it mean?"
In looking at DDT667's two peaks I'll agree they do not look pretty but how does that actually relate to the actual measured frequency response and the sonic character of the circuit?
I have seen the "ps resonant blips" in measured frequecy response plots but they only seem to show up outside of the passband. In the sim below I would expect to see the peak at 10hz show up as a dip in the rolloff of the low frequencies but assuming a full bandwidth amp, will the 60hz bump also show up?
dave
Follow Ups:
Variations in output Z don't generally correlate well with the filter's "forward" frequency response. That's why these filters need to be analyzed from both directions. What does it mean? Difficult to quantify precisely. Most amplifier designs are susceptible to modulation of their B+ with various symptoms; distortion, attenuation, degradation of dampening, etc. It's not clear to me how high PS output Z can become before such symptoms are audible, so I simply design supplies to be as low and flat over frequency as possible.
--------------------------
Buy Chinese. Bury freedom.
I put in the L resistive values , adjusted R1 to 150 and added ESR for caps C1 & C2 (just a guess at this point) so it would look closer to TK's graph.
L1 is the Triad C56U and L2 is one of drlowmu's designed chokes.
That looks much better, but I need to question whether the impedance rise below 100 Hz might be audible. It would be interesting to SPICE an entire SE amp, feed it with this supply, and look to see what's happening at both the output of the supply and output of the amp. Alternately, one could build this supply, drive an SE amplifier, and then probe the B+ line with a scope while delivering audio power to a load. The question is how much that low frequency rise will allow the B+ to wiggle around...
--------------------------
Buy Chinese. Bury freedom.
This is what I have as a filter with my RH84 project amp.
3 stage LC flywheel to finals.
Add an UF4007 isolation diode + 1K ohm R dropper + C4 20uF//200K bleeder (to driver stage) for the complete filter. The spice Z vs. Hz graph looks quite different.
As a full range amp, perhaps there might be some "psychoacoustic" effect as Chip647 would suggest, but who knows?
I did see some sidebands coming up an octave or two beyond the 120Hz ripple with a different flywheel filter on my spectrum/distortion graph.
Might not even hear anything unusual if you are using bass-shy bookshelf speakers or in a multi-amp system driving some horns, so who knows?.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: