RF heating
Hi,
I'm open to persuasion, but as I see it now; For those of us who use CD players, this is not viable option. Unless the frequency is in the very high 100's of KHz, artifacts will be produced which will mix with HF audio.
Ways round it that I can see:
1 Brick-wall 44.1KHz filter - undesirable
2 Perfectly linear stages in amp - unnatainable
Persuade me otherwise...
Cheers,
Hi,
I'm open to persuasion, but as I see it now; For those of us who use CD players, this is not viable option. Unless the frequency is in the very high 100's of KHz, artifacts will be produced which will mix with HF audio.
Ways round it that I can see:
1 Brick-wall 44.1KHz filter - undesirable
2 Perfectly linear stages in amp - unnatainable
Persuade me otherwise...
Cheers,
..RF in audio...
I just hate the thought of RF anywhere near the audio stages. I have had so much grief cleaning out RF from the ss amplifiers that I have designed and made down the years that I am completely against RF heating as a concept. But that is just me
Please prove me wrong and show me how it is possible to use RF in audio and improve the sound... if you can then lots of interesting possibilities open up like switch mode HT supplies....
...and little cheap output transformers by power amplifying the audio on a nice rf carrier and then low pass filtering into the loudspeaker...
of course I might just be being reactionary as I won't have remote control on my valve amps either
ciao
James
I just hate the thought of RF anywhere near the audio stages. I have had so much grief cleaning out RF from the ss amplifiers that I have designed and made down the years that I am completely against RF heating as a concept. But that is just me
Please prove me wrong and show me how it is possible to use RF in audio and improve the sound... if you can then lots of interesting possibilities open up like switch mode HT supplies....
...and little cheap output transformers by power amplifying the audio on a nice rf carrier and then low pass filtering into the loudspeaker...
of course I might just be being reactionary as I won't have remote control on my valve amps either
ciao
James
In my all DHT mono amps I use a 7805 with a 1 ohm res and a 1,000uF cap in front of it, and a .22uF cap after it. (thanks John ) No hum, and no bleached sound (although I'm not sure what is meant by that).
For the purists, I tried using batteries - it's just not worth the space and effort. This cheap solution really lets you enjoy the music.
) No hum, and no bleached sound (although I'm not sure what is meant by that).For the purists, I tried using batteries - it's just not worth the space and effort. This cheap solution really lets you enjoy the music.
Joel,
I'm glad that your findings concur with mine. I haven't noticed any definable difference - except less hum; The DC supplies being filtered of any common mode noise.
For me though, the subject of AC and RF heating is still of interest if only to "even out" cathode wear, and cover for internal spacing variations.
Cheers,
I'm glad that your findings concur with mine. I haven't noticed any definable difference - except less hum; The DC supplies being filtered of any common mode noise.
For me though, the subject of AC and RF heating is still of interest if only to "even out" cathode wear, and cover for internal spacing variations.
Cheers,
...no dc - now what?
Having a little hum through the DHT phono pre I'm playing with I needed to come up with a solution for quietening them down without using dc. I started playing with chokes and caps and I was having some success when I can across Stephen Robinson site Izzy Wizzy Audio . I liked his approached to the problem and I have adopted his topology with goods results. The heater psu is shown below and works very well for me too.
Hi Joel!
Nice to have you back posting in Tubes. 'Bleached' sound has some of the tone of acoustic instruments diminished - it's a very subjective assessment and very unreliable from memory but quite clear with A/B style testing - to me a least.
ciao
James
Ok so it's dc! but it's not regulated and it's very quiet and doesn't bleached or grey the sound...
Having a little hum through the DHT phono pre I'm playing with I needed to come up with a solution for quietening them down without using dc. I started playing with chokes and caps and I was having some success when I can across Stephen Robinson site Izzy Wizzy Audio . I liked his approached to the problem and I have adopted his topology with goods results. The heater psu is shown below and works very well for me too.
Hi Joel!
Nice to have you back posting in Tubes. 'Bleached' sound has some of the tone of acoustic instruments diminished - it's a very subjective assessment and very unreliable from memory but quite clear with A/B style testing - to me a least.
ciao
James
Ok so it's dc! but it's not regulated and it's very quiet and doesn't bleached or grey the sound...
Attachments
...arghhhhhh he got me!...
Joel said
Well, I assume that for regulation as a noun to be applied an active regulating device or two needs to be present in the circuit.
Since chokes, caps and resistors are defined as passive components any regulation (verb) that occurs is pure serendipidy...
ciao
James
Joel said
What do you think all those chokes are doing?
Well, I assume that for regulation as a noun to be applied an active regulating device or two needs to be present in the circuit.
Since chokes, caps and resistors are defined as passive components any regulation (verb) that occurs is pure serendipidy...
ciao
James
Hey guys.
Regulation is two things. These days it tends to mean active voltage (or current, if specified) stabilization. Before such devices were in common use it meant, with a voltage or percentage, the amount of change in voltage over a change in current, say, the voltage dropped 5% when current was increased from half load to full load.
To say that a standard power supply (say, FW > CLC) has no regulation is ignorant.
Tim
Regulation is two things. These days it tends to mean active voltage (or current, if specified) stabilization. Before such devices were in common use it meant, with a voltage or percentage, the amount of change in voltage over a change in current, say, the voltage dropped 5% when current was increased from half load to full load.
To say that a standard power supply (say, FW > CLC) has no regulation is ignorant.
Tim
Anyone for saturable inductors?
Tektronix used to regulate AC by placing a saturable inductor in series with the heater transformer. The inductor had a winding which was driven by DC derived from the heaters, regulating the AC heaters. I salvaged one of these inductors from a 555 oscilloscope, but it fell foul of the two-year-rule some time ago...
Tektronix used to regulate AC by placing a saturable inductor in series with the heater transformer. The inductor had a winding which was driven by DC derived from the heaters, regulating the AC heaters. I salvaged one of these inductors from a 555 oscilloscope, but it fell foul of the two-year-rule some time ago...
Distorted AC
Yes. Saturable inductors must distort the AC waveform (as do constant voltage transformers). I was just throwing in some useless information.
I think I'm going to have to use traditional AC heaters. Sigh.
Two-year-rule (not to be disclosed to distaff side): Unused stuff has to justify its continued existence every two years, otherwise it is ruthlessly disposed of. Output transformers and valves have remarkable staying power, but electrolytic capacitors are not nearly as resilient. Chassis fall at the first fence.
Yes. Saturable inductors must distort the AC waveform (as do constant voltage transformers). I was just throwing in some useless information.
I think I'm going to have to use traditional AC heaters. Sigh.
Two-year-rule (not to be disclosed to distaff side): Unused stuff has to justify its continued existence every two years, otherwise it is ruthlessly disposed of. Output transformers and valves have remarkable staying power, but electrolytic capacitors are not nearly as resilient. Chassis fall at the first fence.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.