 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
98.253.218.50
In Reply to: RE: 5687 & OB2 as an excellent HT regulator posted by danlaudionut on February 24, 2015 at 13:08:56
Yes, this version of the basic circuit will work.
With a fixed voltage (to ground) at the grid of the 5687, the output impedance of the regulator will be approximately 1/Gm of the tube (which depends on the cathode current and plate-cathode voltage). With roughly 200 V across the triode and 10 to 30 mA current, that output resistance ranges from 200 to 100 ohms (for a single triode).
Personally, I would break R3 into two 1k to 5k resistors in series, with a good film capacitor from the junction to ground. The 0B2 can handle 0.1uF directly across the tube, and the resistor after it will reduce instability caused by the shunt capacitance: the series resistance before the capacitor will improve the high-frequency noise filtering.
Follow Ups:
Thanks for explaining this to me (us). Will the effect of adding a film cap across OB2 be the same as adding a cap accross the zener diode? I never liked that, it sucks the life out of high frequencies. How is a value of this cap related to high frequency roll-off?
Putting a capacitor directly across a Zener diode, which shows a very low resistance when conducting, is not very efficient as a filter. A series resistor between the Zener and the capacitor improves the filtration dramatically (so long as the rest of the circuit allows the series resistance). Gas VR tubes have a maximum capacitance specification, typically 0.1 uF, above which they are liable to relaxation oscillation (cool flashing light, but otherwise useless).
But this is powering an SPDIF buffer is it not? Nothing you can do to this power supply can affect the audio frequency response as being suggested. Round the signal off too much or apply too much ringing and you will get errors. That is hear clicks and pops.
Want to "liquify" the high end just a tad? Well with digital audio you will need to learn DSP programming. Because tweaking a cap in the power supply ain't gonna do it!
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:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
