2A3 for a headphone driver‼. A good way to become deaf......I would also be very much interested in a 2A3 SE headphone amp....I ended up building the Tubelab SE with a 45. It can just as easily be built for 2A3 or 300B....
Some details (and pics) of the build can be found here:
After a 14 year run, the TSE must DIE!
in response to the questions I received about this, I simply disconnected the speakers from my 2A3 TSE-II amp and connected the cans directly to the OPT, mainly to see how quiet it would be.....Sounds nice to me. Tried all my headphones too.
If they are the same brand and construction they will be fine. Different tubes of the same type number are probably OK too. The real problem arises when several different non controlled tubes are wired in series across the line voltage. The fastest heating tube gets blown up.
Some details (and pics) of the build can be found here:
After a 14 year run, the TSE must DIE!
in response to the questions I received about this, I simply disconnected the speakers from my 2A3 TSE-II amp and connected the cans directly to the OPT, mainly to see how quiet it would be.....Sounds nice to me. Tried all my headphones too.
If they are the same brand and construction they will be fine. Different tubes of the same type number are probably OK too. The real problem arises when several different non controlled tubes are wired in series across the line voltage. The fastest heating tube gets blown up.
Here's the circuit I'll be dealing with for subsequent measurements. The 12AQ5 output tube is biased with a discrete shunt regulator with low impedance for maximum gain. It also gives me a lot of freedom in setting the output stage bias current without a lot of messing around..
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I've been doing some messing around with the basic design with the intent of changing with the inner feedback loop to provide some excess gain, allowing some global feedback to stiffen the transformer at low frequency.Here is the resulting circuit...
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And also legally deaf.
It's not due to exposure, but to an ugly malady called Meniere's Disease. This is a situation where symptoms of extreme vertigo and debilitating dizziness come and go, and usually take a little piece of your hearing with it each time. I have had this for nearly 30 years. The first encounter left me bedridden for over a week. Any attempt to get out of bed resulted in severe dizziness and nausea.
Two prominent audiologists told me that I would be completely deaf by age 50. I'm 67 now and getting quite deaf. The constant roar of tinnitus is quite loud, and often accompanied by other sounds that are not really happening. Most often its the sound of broken glass, or the "rocks in my head" clashing. These sounds are caused by the inner ear fluid crystalizing.
Even with my deafness, I don't need or want 2 watts into a pair of headphones. However, the 2A3 tube amp is a normal speaker amp with a 10 ohm resistor wired across the output and the cans in parallel with the resistor. So when the amp is cranked to LOUD It's putting around 4 volts RMS across that resistor. When those 4 volts are applied to the 32 ohm phones, the power is a very loud 1/2 watt.
Nobody, not even me, needs to turn it up to LOUD, but the reason for the test was to explore the other end of the spectrum. Is the TSE-II quiet enough to feed cans directly, and it appears that is the case.
The one concern I have left is the tendency for the gain to try and re-cross 0dB at high frequency. For a closed loop system this can be problematic. I have the option of adding a cap from drain to ground on the input mosfet this might make the gain stay below zero at high frequency. However, last time I tried this, I damaged the input mosfets. Maybe a series combo of something like 47-100 p + 1k ohms will do the trick.
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