What is the tube parallel to a source or emitter follower? I consider using
such a follower to drive a phono or xlr signal output from a preamp. I work
as a cmos asic designer, but I have no relation to tubes at all. Are there
any tube tutorials out there?

What are the main differences between a transistor source/emitter follower
and one made with a tube? (Sound, threshold voltages)

What kind of power supplies will I need?

Will the tubes be expensive and hard to come by?


Regards,
Børge

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"Børge Strand" ha scritto
nel messaggio ...
What is the tube parallel to a source or emitter follower?

It should be a cathode follower, from a conceptual point of view..

I consider using
such a follower to drive a phono or xlr signal output from a preamp. I
work
as a cmos asic designer, but I have no relation to tubes at all. Are there
any tube tutorials out there?

Yes indeed. Have a look at http://duncanamps.com/ ,
http://www.triodeel.com/tlinks.htm , http://www.vt52.com/ ,
http://www.vacuumtube.com/FAQ1.htm

Or, if You want, buy a copy of the RCA Radiotron electronic handbook. Costs
a lot but it is a pro tool.


What are the main differences between a transistor source/emitter follower
and one made with a tube? (Sound, threshold voltages)

I prefer not to talk about sound, too much snake oil around. Something
better must it be... there are lots of RATs wasting time & $$$$ for tubes,
we cannot be all nuts.
As per voltage, it's quite another "world": tubes deserve (usually) 200+ V
dc to work properly.


What kind of power supplies will I need?

Massive. No less than 3-4 kg of iron, if You include a filter choke
(mandatory for a pre-amp)


Will the tubes be expensive and hard to come by?

If You watch out for snake oil sellers You can easily get quite decent,
freshly made Czech, Yugo or Russian pre-amp tubes for some 6-7 $ each. As
per the NOS (new old stock) tubes, You can try at some local garage sale.
With some luck You can find some original Ericsson tube for half an Euro.



Regards,
Børge

Welcome among the Rodents

Fabio


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"Børge Strand" wrote
in message ...
What is the tube parallel to a source or emitter follower?

It's a cathode follower (CF), a very common circuit.

I consider using
such a follower to drive a phono or xlr signal output from a preamp.
I work
as a cmos asic designer, but I have no relation to tubes at all. Are
there
any tube tutorials out there?

Sorry, don't know - except for older text books.

What are the main differences between a transistor source/emitter
follower
and one made with a tube? (Sound, threshold voltages)

The tube circuit needs a B+ of some 100 volts or more. It sounds the
same - CF's add very little or no distortion.

What kind of power supplies will I need?

Heater voltage and B+ suuplies.

Will the tubes be expensive and hard to come by?

Not really. Try a double triode like an ECC83, 1/2 as an amplifier
and the other as a CF output stage.

Regards,
Børge

Cheers,

Roger
------
Roger Jones, P.Eng.
Thornhill, Ontario,
Canada

"Børge Strand" wrote:

What is the tube parallel to a source or emitter follower?

Its the cathode follower.

To read alot about tubes,
go to the Radiotron Designer's Handbook,
4th Edition, 1955.


I consider using
such a follower to drive a phono or xlr signal output from a preamp. I work
as a cmos asic designer, but I have no relation to tubes at all. Are there
any tube tutorials out there?

Try cathode follower in Google.

Plenty of tube info on the web.

The best understanding is when you build a tube amp
and analyse what you're doing.
Same goes for solid state amps.
Not all knowledge comes from books, or the web.


What are the main differences between a transistor source/emitter follower
and one made with a tube? (Sound, threshold voltages)

transistor preamps use +/- 15 volt supplies, and say 10 mA
currents in emitter follower output buffers.

Tubes need 250v, and 5 mA, for the same application.



What kind of power supplies will I need?

Ones capable of 200 to 350v, at 50 mA.


Will the tubes be expensive and hard to come by?

Compared to a single transistor worth 20c, a tube for a preamp
might be $20.
Yeah, tubes are expensive, but so is lunch at a restaurant.

Regards,
Børge

But the sound that you hear with tubes is food for the ear.

Patrick Turner.





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What are the main differences between a transistor source/emitter


follower


and one made with a tube? (Sound, threshold voltages)



The tube circuit needs a B+ of some 100 volts or more. It sounds the
same - CF's add very little or no distortion.


The output impedance tends to be higher with a cathode follower than an
emitter follower.
Like a hundred ohms vs a few ohms impedance. Also the voltage "gain" of
a cathode follower tends
to be slightly lower than an emitter follower. "Gains" of 0.7 vs 0.99
or so.

Also tubes come only in one "flavor". No complement as in NPN and PNP.