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Unusual amps..

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#103
Yes but they need tuning so you're out of luck. 😀 Try to contact Lance, I believe he's much more generous than his disciples. Or ask Globug. Mine is 'tuned' but I hate drawing out schematics.

A punk comes along and now everybody is interested, despite being non hifi in nature. I gotta laugh.
 
#104
You need to breath in a lot of Krylon paint fumes in order to tune them.

What got my interest was the purported good sound of the parafeed. Seeing as the floating version has some 2nd Harmonic signature, this would seem likely connected. But then when the Krylon master claims .0001 distortion as well, my expectations for an explanation plummeted.
 
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#105
Cassiel said:
Yes but they need tuning so you're out of luck. 😀 Try to contact Lance, I believe he's much more generous than his disciples. Or ask Globug. Mine is 'tuned' but I hate drawing out schematics.

A punk comes along and now everybody is interested, despite being non hifi in nature. I gotta laugh.
Click to expand...

I'm always open to ideas,

Its interesting that you already knew that the tuning refered to was not just cap and resistor types.. 🙂

The ideas of unusual amps..LOL
What are you not telling us?

Regards
M. Gregg
 
#106
Here's a tip for you Gregg, go to the Six Moons site and look up for the Leben- 300. It's in the archives. Download the hi-re pics and do reverse engineering. Really simple except for the feedback loop which has bass compensation stuff but the main circuit is easy to get. That's a floating paraphase, the modern version. Play the detective. It's fun.

What got my interest was the purported good sound of the parafeed
Click to expand...


Yes, SE midrange plus better bass.
 
#107
H.H. Scott in the Scott 222B used a variation with a 6BL8 using the pentode section for the first stage and the triode section for the second stage. Instead of a fixed divider they had a pot for "AC Balance".

Also the Magnavox 93XX series used it with a 6EU7.

Zenith Model 11S474 Chassis 1103 used a 6Q7G for the first stage and 6J5G for the second stage.

I'm sure there are others as well.
 
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#109
Cassiel said:
Here's a tip for you Gregg, go to the Six Moons site and look up for the Leben- 300. It's in the archives. Download the hi-re pics and do reverse engineering. Really simple except for the feedback loop which has bass compensation stuff but the main circuit is easy to get. That's a floating paraphase, the modern version. Play the detective. It's fun.




Yes, SE midrange plus better bass.
Click to expand...

Are these the pics you mean?

6moons audio reviews: Leben CS-300X

Regards
M. Gregg
 
#111
The bottom pic. Looks like the same circuit as in Morgan Jones 3rd ed. page 402, except I can't tell if the cathodes of the 12AX7s are tied together. 200 K Ohm plate resistors, 270 K grid leaks for the EL outputs, 2k grid stoppers, 2 Meg divider network back to 12AX7b grid. Can't tell if there is a balance pot in there. Looks like it's missing the 50K build out resistor.
 
#112
hero_open2.jpg



Have you got a link to a schematic?
Click to expand...

No but it's in my head. Any doubt ask.


EDIT. I believe the plate resistors are 100k. Yes cathodes tied together but first one with a resistor before the bypass cap for the negative feedback loop. Cathode resistor 560 Ohms. Then the divider after the coupling caps with two 1M resistors and that's it.
 
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#116
So the Leben 300 does not have a balance pot?

The H.H. Scott 222B has a mysterious capacitor compensation network (C24, C29, R38) on the grid of the top output tube. Maybe it is compensating for the higher output impedance of the 6BL8 pentode driver by boosting the 6BQ5 grid drive at HF where the 6BQ5 input cap. would be loading it down.

The Zenith schematic looks like the non-floating paraphase.
 
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#118
smoking-amp said:
So the Leben 300 does not have a balance pot?

The H.H. Scott 222B has a mysterious capacitor compensation network (C24, C29, R38) on the grid of the top output tube. Maybe it is compensating for the higher output impedance of the 6BL8 pentode driver by boosting the 6BQ5 grid drive at HF where the 6BQ5 input cap. would be loading it down.
Click to expand...

Oh look its tuned..LOL

May the force be with you..LMAO

Regards
M. Gregg
 
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