8417 to 6L6

[rdrgtr]

I have a bag of 8417 tubes.  Can I pop these in my typical fender 50w amp?  If not,  can I pop them in to check the bias just for matching purposes.

Thanks.

[Steve_P]

Look for guys with Guild Quantum Thunderbasses. They have separate bias trims for each tube.
 8417's require far less bias voltage than a 6L6 - about half, IIRC. If you can dial the voltage down to -17 volts, you could match them, I would expect.

[Willabe]

Can I pop these in my typical fender 50w amp?

NO!

8417's are _not_ drop in replacement tube for 6L6's because of tube pinout and heater current draw.

Pin 1 & 3 are both plate on 8417, pin 3 on 6L6 is plate and pin 1 is no connection. Fender and others used pin 1 on 6L6 (and 5881, 6V6, ect.) as a solder tag for 1K5 grid stop, pin 1 to pin 5.

Also 8417's take 1.6A each for their heaters, 6L6's take 0.9A each for their heaters. That's almost double the current draw.  

If your PT has enough heater current to handle 8417's, make sure there's nothing on pin 1 if you want to try them in place of 6L6's.

If not, can I pop them in to check the bias just for matching purposes.

You might/should be able to pop a pair in (just long enough) to match them _ IF _ there's nothing on pin 1 of the amp _ AND _ you take out _ ALL _ the pre amp, vibrato/tremolo and reverb tubes to free up the extra heater current. Each 12_ _ 7 you pull will free up 300mA (.3A).

2 @ 6L6= 1.8A, 2 @ 8417= 3.2A, so you need 1.4A more. 4 @ 12 _ _ 7 = 1.2A, should be fine just to match up a few pairs of 8417's. 


 
                       Brad      

[PRR]

> I have a bag of 8417 tubes

Some 8417s are very valuable; so much that you can trade them for a bag of top-notch 6L6.

They are not drop-in for 6L6, if adapted will not make more power than 6L6, and the less-valuable 8417 are so doggone fragile that I would NOT run them in overdriven guitar.

[rdrgtr]

Thanks guys.  The fender build is my own and nothing is on pin 1. 

[RWood]

8417s can take a high plate dissipation but the screens are very sensitive.

I've worked on a few of the aforementioned Guild Thunderbass amps and they actually used a tube-regulated voltage for the screens of the 8417s. It has an adjustment pot so that you can dial in exactly 300vdc. That's a lot lower than typical 6L6GC screens are run, unless they are in ultra linear mode. Just saying, be careful with your screen supply. You will be rewarded for doing so - 8417 when running right is a nice tube!

Rwood

[albinoguitman]

Do you still have a bag full of 8417's?