#2
There are cathode followers in 90% of tube amps...thats how they are mostly built...

I can only think of possibly ENGL's that arent based around one....

If you dont know what it is...why do you need to?
I've bought, sold, and traded more gear than I care to admit.
#3
If you put Tungsols in a cathode follower slot you will f them up. Just checked the boogie boards and they don't have a cathode follower but apparantly Tungsols are hard on the filaments.
#4
depends on the amp really...

and honestly....i didnt know that a certain brand of tube can **** up your amp....in fact...im sure its not
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#6
OHHHH...sorry, i get it now!!!!
I've bought, sold, and traded more gear than I care to admit.
#9
Cathode follower: essentially an impedence buffer. High Zin, really really low Zout (for a tube). (Zin and Zout = impedence in and out)

Example: typical 12AX7 stage has a Zout of Rp||ra = 62k5||100k which is probably about...? 40k maybe? (don't have time for math right now)

now, tone stacks have Zin's in that range (not to mention the dynamic impedence...).

Because Zout of a 12AX7 stage is about the Zin of the tone stack, you are driving that poor tube HARD, you're losing gain and low and end response.

The solution is the cathode follower...basically, it gives you a gain less than one (about .95-.99...so, it actually reduces the signal size) and in exchange it has a Zout of about 600R. Which means that the stage before can stay nice and "stiff" and not work hard to get maximum gain, and the CF "drives" the signal into the tone stack, which it does with ease.

Neat circuit.

The problem with it is that is that at powerup, things that should be at low voltage are at high voltage, and you can get arcing inside the tube. this can happen to every brand, it's the nature of the beast. So go get whatever tube sounds best, put it in, and rock out.
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#10
^It happens to every tube brand, but Tung-Sols and Sovtek LPS' are notably more susceptible to dying in CF positions than others.
#11
Quote by Roc8995
^It happens to every tube brand, but Tung-Sols and Sovtek LPS' are notably more susceptible to dying in CF positions than others.


Funny....I'd heard the same thing about JJs...

I always throw a diode and a pair of resistors around CFs in the amps that I build, simple protection mechanism that prevents arcing/tube death.
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#12
The CF stage is usually the preamp position that handles an amps active eq. A good rule of thumb is not to put a Sovtek LPS in that position. (V3 in my amp)
I never heard of Tungsols having an issue with that spot.
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#13
Quote by Van Noord
The CF stage is usually the preamp position that handles an amps active eq. A good rule of thumb is not to put a Sovtek LPS in that position. (V3 in my amp)
I never heard of Tungsols having an issue with that spot.


It drives passive TS's too...
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#14
i've seen people on the boogie boards use tungsols in their mark IV's and haven't heard of any problems. it seems possible that the tube could burn out, so don't completely write it off.
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