So, in our world of programmable analog circuit arrays and perfect rail-to-rail opamps, when would you *need* to use a tube? When does using silicon not make sense?
I saw it was a pentode and though "WTf I though you used single end triodes for audiophile cred, pentodes and push-pulls got the distortion too low"
Then dave had the schematic drawn out...
Could you just pull the valve and connect the grid to the anode?
Could you just pull the valve and connect the grid to the anode?
Not in this design. The anode goes to the positive rail.
You'd have to connect the grid to the cathode - but, yes, your basic idea is ok.
Except for one thing - the signal would no longer go through a valve, removing the premise for it being there.
I saw it was a pentode and though "WTf I though you used single end triodes for audiophile cred, pentodes and push-pulls got the distortion too low"
Then dave had the schematic drawn out...
Pentode in SE usually has higher distortion. Connecting it in ultra-linear mode lowers the output power and distortion, triode mode is lowest power and lowest distortion.
A JFET has IV curves almost exactly like those of a pentode, however, I do not know of any semiconductor device that has the IV curves of a triode.
Personally I prefer exact sound reproduction, not distorted, hence I use high end DAC coupled with monitor grade IEM.
Could you just pull the valve and connect the grid to the anode?
Not in this design. The anode goes to the positive rail.
You'd have to connect the grid to the cathode - but, yes, your basic idea is ok.
Except for one thing - the signal would no longer go through a valve, removing the premise for it being there.Yes, I meant Cathode; damn electron flow...
How high is the anode voltage used and how is it created in this headphones amp?
- There are HOT parts accessible to the user (the tubes)
- There is a mechanical danger of breaking the glass tubes and cut yourself with the glass.
This toy should not be sold, even in China.
Best regards
EN60065 (safety requirement for audio, video and similar electronic apparatus) and it's equivalent regulations are violated in at least 2 points:
- There are HOT parts accessible to the user (the tubes)
- There is a mechanical danger of breaking the glass tubes and cut yourself with the glass.
This toy should not be sold, even in China.
I discovered a long time ago it makes no difference which way the little packets of energy go, it all works out just fine.
Also just too many parts to keep track of
24v K-A and a cathode follower arrangement? Whats the point? It would give lower output impedance, but feeding into an op-amp its not like that would be required. Not enough voltage to make any useful gain anyway. Wonder how far out of the linear operating range it is.In my opinion there is no point, That is not a good tube for a cathode follower, the designer is not taking advantage of the high input impedance a vacuum tube offers, and as you pointed out the plate voltage (B+) is too low.
The designer isn't even trying to prove something.
Why not?
build a 30W headphone amplifier using all tubes, no output transformer, using an output differential amplifier with cathode output. (to keep the voltage and impedance low)? Run it on say............125V regulated(+/- 65.5V).
That would be a concept amplifier worth building, if for no other reason than to prove the idea.
Why 30 watts, not many headphones can accept even peaks at that level? About the only thing that might differentiate a 'headphone amp' form other audio amps is that it might be designed to only work at the higher output impedance of most headsets.
No frequency response/distortion/noise measurements? Am leaving disappointed.
And why would you "buffer" something that's going to be fed into an op-amp? The op-amp impedance isn't high enough?
Still, I guess I'm missing the point. I'm not the target market for this. I'm sure looking at glowing tubes will improve the sound quality for many people.
Well, you guys heard ciccio, mains voltage and glass objects are dangerous!
We better get rid of wall outlets, since the HOT parts are accessible to users... We should also do away with glass cups and bottles as we could cut ourselves!
In fact, personal Faraday cages and sippy cups should be mandatory for everyone to prevent electrocution or severe gashes!