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Old 10th September 2009, 05:34 PM   #1
nhuwar is offline nhuwar  United States
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Default 8608 pentode

Hi all,


Just wondered if anyone has heard of this tube being used in audio applications ?
Any opinions of how the tube performed will be greatly appreciated?

I have 4 old amprex gold pin 8608 and I'm trying to think of something to do with them.
Thanks,
Nick
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Old 10th September 2009, 06:07 PM   #2
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hey-Hey!!!,
With a significant part of the g1 plate curves above its plate dissipation, I'd want to run it at lower g2 voltages. beyond that, it looks like a fine audio tube. If you've got a linestage with balanced output a *VERY* simple amp can be built with just a two-tube, PP power stage. Looks like an easy 6-8W to mee... wishing I had several of them myself.
cheers,
Douglas
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Old 10th September 2009, 06:32 PM   #3
nhuwar is offline nhuwar  United States
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:Well I was thinking about using it as a driver for a 813.


I know it's probably a bit over the top but I think it would look cool to have a ll the tube have plate caps.


Oh and ya my linestage does have balanced outputs too LOL, how'd you know
Nick

Last edited by nhuwar; 10th September 2009 at 06:35 PM.
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Old 10th September 2009, 09:04 PM   #4
RE 604 is offline RE 604  Germany
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The 8608 is an E55L / 8233 with plate caps .

E55L in triode as driver!

Regards , Alexander .
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Old 10th September 2009, 10:07 PM   #5
nhuwar is offline nhuwar  United States
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Does anyone have a load line draw up for either of these tubes?



Thanks,
Nick
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Old 10th September 2009, 10:07 PM   #6
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Quote:
Originally Posted by nhuwar View Post
:Well I was thinking about using it as a driver for a 813.


I know it's probably a bit over the top but I think it would look cool to have a ll the tube have plate caps.


Oh and ya my linestage does have balanced outputs too LOL, how'd you know
Nick
hey-Hey!!!,
813 driver sounds cool... I am driving mine with a 6H6Pi/FQP1N60 cascode. Let me suggest for you E-Linear at 20-25%, B+ of ~600 to plate and screen( the 813's ), and an 8k a-a load. 8608 g2 around 75V, with plate loads of 15-20k and idle current 15-20 mA per.

Or you could build a 'scope and use them for horizontal outputs.
cheers,
Douglas
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Old 10th September 2009, 10:15 PM   #7
nhuwar is offline nhuwar  United States
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I was going for 1kv on the plate of the 813 and running 6500 ohm plate load.

The idea has been in the works for a while it's just changing the driver tube is something new.




Oh this is a se amp though, not a push pull. I was toying with that idea a while back just didn't have the room LOL.


Nick
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Old 10th September 2009, 10:37 PM   #8
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A nice tube for a 1-tube hybrid amp!
I would use it triode strapped, gyrator loaded, to drive MOSFET source follower.
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Old 10th September 2009, 11:46 PM   #9
nhuwar is offline nhuwar  United States
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Gyrator loaded, I've never heard of that one. But then again there's a lot in this obsession I haven't learned yet.
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Old 11th September 2009, 01:34 AM   #10
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Quote:
Originally Posted by nhuwar View Post
Gyrator loaded, I've never heard of that one. But then again there's a lot in this obsession I haven't learned yet.
Here is the basic version that I used several years ago in a mic pre:

Click the image to open in full size.

Here is another version Hearinspace implemented in his high-end amp:

http://wavebourn.com/forum/download.php?id=125&f=7

Last edited by Wavebourn; 11th September 2009 at 02:01 AM.
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