any weaknesses of the elevated / regulated heater?

[idnotbe]

though i am not familiar with circuits, i know the elevated / regulated heater is often used for reducing 12A_7 noise.
but also i know some of purists do not like the idea of the elevated / regulated heater , such as Soldano, Komet, Morgan....

just curious...
are there any weaknesses of the elevated / regulated heater that the purists hates ?

[Orson Maxwell]

Well, there is the Vhk rating (heater to cathode voltage) for each tube that should not be exceeded. Also by saturating the leakage current you theoretically introduce a bit of regular noise, but I don't think this is of concern, especially in guitar amps.

[tictac]

I've used both AC and DC heaters and for my tastes the DC heaters seem to change the tone in a way I don't care for. Call it slightly muted, less lively, i.e. some slight but perceptible treble cut. I've hear some say they can't hear a difference but I can... Maybe it doesn't make much difference in high gain amps. I have also tried a DC reference to the heater CT which doesn't seem to have any signal denigration problems.

TT

[tmod]

The only issue is added complexity. As long as the max heater to cathode voltage is observed there are no reliability issues with heater elevation, so that is always a safe option. And usually it's good enough, and a safe option.

DC heaters on the other hand involves a few potential issues. Simply rectifying the DC voltage will add ripple voltage, that could show up as noise. Higher frequency noise will move capacitively much easier, and might add more noise than leaving it unregulated. Higher frequency noise is also closer to the signal than 50/60hz, and will also be more noticeable.

Regulating heater voltage has its own pitfalls. First there is the reliability issue, as there is another piece that might fail. Also most regulators can add even higher frequency noise under certain circumstances, potentially adding more noise.

All in all, pure DC is strictly superior that AC, but is much harder to implement. A well regulated DC supply also involves risks if you don't know what you are doing, and elevated AC is usually good enough and much easier/risk free to build, and carries no reliability risks.

Sent fra min SM-G930F via Tapatalk

[dorrisant]

I've used both AC and DC heaters and for my tastes the DC heaters seem to change the tone in a way I don't care for. Call it slightly muted, less lively, i.e. some slight but perceptible treble cut. I've hear some say they can't hear a difference but I can... Maybe it doesn't make much difference in high gain amps. I have also tried a DC reference to the heater CT which doesn't seem to have any signal denigration problems.

TT

It might be worthwhile to do some a/b testing with a signal gen and a spectrum analyzer...

[tmod]

I've used both AC and DC heaters and for my tastes the DC heaters seem to change the tone in a way I don't care for. Call it slightly muted, less lively, i.e. some slight but perceptible treble cut. I've hear some say they can't hear a difference but I can... Maybe it doesn't make much difference in high gain amps. I have also tried a DC reference to the heater CT which doesn't seem to have any signal denigration problems.

TT

It might be worthwhile to do some a/b testing with a signal gen and a spectrum analyzer...

Definitely!

Sent fra min SM-G930F via Tapatalk

[trobbins]

It might be worthwhile to do some a/b testing with a signal gen and a spectrum analyzer...

Posts #128 and #170 in diyaudio thread:
http://www.diyaudio.com/forums/tubes-va ... ac-17.html