Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

Hi Jeff ,

What phones (impedance) do you use ??
I use a 300 ohms Sennheiser (old HD540) and use the 6AS7-G
(= st shape 6080) as a beefy cathode follower . My driver stage is the
good ole 6SN7 in an "Alan Kimmel" Mu-stage with an EF184 as the
active load for the 6SN7 .
If you use low imp. phones you could go for a normal SE stage or OTL
if you have 2 x 6080 .

Regards ,

Ronald .


"Jeff Kapp" schreef in bericht
m...
Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

"Jeff Kapp" wrote in message
m...
Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

Yes

"Jeff Kapp" wrote in message
m...
Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

Just look up "cathode follower", set up a 6080/6AS7 circuit with maybe 30 to
50mA flowing.

Tim

--
"I have misplaced my pants." - Homer Simpson | Electronics,
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Hey Tim ,

Just look up "cathode follower", set up a 6080/6AS7 circuit with maybe 30
to
50mA flowing.

Bin there , done that ..... (30mA)
As I said works great for 300 ohms load , but not on 8 ohms ......

Ronald .

"Ronald" wrote in message
...
Bin there , done that ..... (30mA)
As I said works great for 300 ohms load , but not on 8 ohms ......

Yep. So run it maybe 150V 150mA. Should get a good 60mW into it, and given
headphones good for even 80dB/mW (my 32 ohm phones are 90-some (98?) per
mW), that's a pretty good 98dB. I sincerely doubt they are that bad, but if
they are, gee get some better headphones. :^) Or just plug 'em into the
amp's output for pete's sake.

Tim

--
"I have misplaced my pants." - Homer Simpson | Electronics,
- - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting
and Games: http://webpages.charter.net/dawill/tmoranwms

Ronald wrote:

Hey Tim ,

Just look up "cathode follower", set up a 6080/6AS7 circuit with maybe 30
to
50mA flowing.

Bin there , done that ..... (30mA)
As I said works great for 300 ohms load , but not on 8 ohms ......

Ronald .

The 6080/6AS7 is good for 20 watts of dissipation, both halves, so if
Ea was 50v, then Ia could be 400 mA.
I know this because I use a couple as pass elements in a HV regulator.
However, one would never run a tube flat out in class A for a headphone amp,
because only a small output power is wanted.
But using a supply of +50v to +100v would be fine with
100mA of anode current, and use the tube as a cathode follower,
driven by almost any medium U triode..
Then use a choke as the cathode load to pass the DC to 0V, and some resistance,

so that you can bias the 6080 grid to 0V, and still have the cathode voltage
able to regulate Ia as in the case of a normally cathode biased stage.
The phones are then cap coupled, for 8 ohms or higher via a 4,700 uF x 50 or 63
volt rated cap;
something above the cathode voltage. ( The cap should be biased with some DV).

If you have 70mA rms max of output current into 8 ohms,
that will make 40 milliwatts of power, and I suggest that
would waken the dead with headphones.
The voltage swing is only 0.56 vrms,
but if Ia was 200 mA, you'd get 1.12 vrms and 0.16 watts of power max.

An alternative to the choke is a transistor CCS.
And an alternative to a cap coupled output is a balanced output using
the two halves of the 6080 with a pair of CCS, so the phones connect
cathode to cathode.
Or an ungapped auto transformer with a CT to an RC biasing circuit is the rolls
royce,
because you can have a variety of load choices.
The drive to the 6080 is from the same twin triode as the SE amp, except
it can be set up as an LTP.

Such an LTP would need only an SE input if one side is grounded
and a CCS tail is used to the cathodes.

The PP OPT for the phones can have taps for
300, 150, 100, 32, 8 ohms easily placed along it,
and can be wound on a toroidal core using a core rated for say
50VA mains use.
The winding should have about 1,000 turns.

The transformer coupling reduces thd, since the tubes are matched
so they will always see a correct load, which never occurs with
OTL amps connected to 8 ohm loads.
But the OTL amp with headphones is OK because the power is so low,
and thus thd is low because the power is low.

Its possible to use a full SE CF 6080, with a CCS, and cap couple an AC
transformer
say using something out of one of those low power horrid transformer coupled
transistor amps
of the 50s and early 60s.
The turn ratio and primary inductance should be about right.

Patrick Turner.

Jeff Kapp wrote:
Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

http://hem.passagen.se/ebcpecz/Tube/...headphone.html

Enjoy!


Adam

Adam Stouffer wrote in message ...
Jeff Kapp wrote:
Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

http://hem.passagen.se/ebcpecz/Tube/...headphone.html

Enjoy!


Adam

Thanks Sir
This link is very useful.
regards.

"Jeff Kapp" wrote in message
m...
Adam Stouffer wrote in message
...
Jeff Kapp wrote:
Is there any simple circuit for headphone amplifier using RCA 6080?
thanks

http://hem.passagen.se/ebcpecz/Tube/...headphone.html

Enjoy!


Adam

Thanks Sir
This link is very useful.
regards.

Yes indeed. Thank you from me too.

Dale