• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

ECC88 tube buffer NEEDED !

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TonyTecson

TonyTecson

Member
Joined 2003
DF96 said:
A well-engineered device which I am sure performs its intended function(*) flawlessly!

(*) extracting money from people who don't understand electronics but think they do understand 'audio'!
Click to expand...


this is not the first time they did this, the chinese boys even came up with a stereo classA kt88 pp amp running with just a 5ar4 rectifer......:crazy:

look under the hood and you will see 4 silicon diodes in a fwb config soldered in, so that pulling out the tube while music is playing does not cut the music off....pretty net huh?:D:D:D
 
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ChrisA

Member
Joined 2008
DF96 said:
You are surely not suggesting that the thermionic rectifier is merely cosmetic? I hope they are not wasting a NOS valve.
Click to expand...

You can bet they are not wasting an expensive valve.

I've seen worse. One was an LED inside a dead tube. They actually drilled a hole up through the base. The point was (according to the ad copy) that the amp had the look of vintage equipment but with modern design. Even that was wrong. Vintage builders never left the tubes visible to the user, only modern gear sold to the audio hobby market has exposed tubes.
 
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DavesNotHere

Banned
Joined 2011
how about a common cathode with a dc coupled cathode follower.

first tube section:

grid input resistor to 330k cathode resistor is 2.4k, plate resistor to B+ is 150k plate is directly tied to other section,

second tube section:

grid is directly tied to 1st section's plate,
plate is direclty tied to b+
cathode has 47k to ground
then a 4.7uf coupling cap
then a 500k to ground loading resistor
connect output jack to 500k node

there you go, b+ around 200 can be as high as 300 and only one cap on the output which is a relatively low output impedance.
5 resistors and a cap and you're ready to rock.
 
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ChrisA

Member
Joined 2008
DavesNotHere said:
how about a common cathode with a dc coupled cathode follower....
Click to expand...

I think that is what everyone is suggesting. I posted this one
The Valve Wizard

I would build it so the resistors are easy to change. The above has pretty conservative values. Higher values give more gain and "tube sound". They are 5 cent parts and what is "best" is a matter of takes and judgment.
 
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