KT88's in my Uberschall

edgeofdarkness

edgeofdarkness

New member
They fit, Bias trim is too high , lowest i could get them was 63 mA
with a 504 plate voltage the online weber calc shows them to be set at 48.6 mA
I dont have any resistors here to complete this right now.. :(

thoughts ?

IMG_3332.jpg
 
nbarts":3ezbxv10 said:
I'd like to see how's this going to work out.
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Just got off the phone with bogner, they just gave me the green light.
Now i just got to get the resistor.
I'll take some photos when i do it.
 
the guy at radio shack handed me 22 and 47 ohm resistors...i wasnt paying attention.

what i asked for were 22k and 47 k ohm resistors. :doh:
to be updated when i get the right resistors.
NOTICE R130 ?
the resistors we need to change to get the bias in range.(for green revision anyways)
IMG_3337.jpg

IMG_3336.jpg
 
Cool! Please update the thread with the values Bogner specified and the tonal differences you hear. I might want to try this too :thumbsup:
 
Rufus Leaking":26roxhhv said:
Cool! Please update the thread with the values Bogner specified and the tonal differences you hear. I might want to try this too :thumbsup:
Click to expand...


no specific values, just need to get it down to operating range, I added a 44k and a 22k and its perfect. with the tubes i have i show a 516 plate voltage, the weber bias calc shows these tubes to be set at 47.4 mA ..i have them right on the dot.
depending on your tubes would depend on what you need to get the bias trim down to.
 
nbarts":2qktqsw8 said:
edgeofdarkness":2qktqsw8 said:
its alive !!! :rock:
Click to expand...

Well??????
Click to expand...


well, i just got it done, so far im loving it, but i am a kt88 fan.
more headroom, LOTS more headroom..less fizzy, the gain is a lot more controllable now.
I'll give a more indepth review after this weekend and i get more play time on it.

KT88Uber.jpg
 
I wouldnt say its tighter, it feels about the same.
I just made a crappy video thats somehow is not in sync , after processing and camera mic clipping it isnt that great , but it might give you a idea.

PS all settings on that channel were at noon except the volume

 
Very cool, my friend, very cool!
I can hear less of that top end sizzle replaced with some defined top end.

What cab & speakers were you running in the video?
 
After playing on it last night and some this morning i can say the clean is cleaner now..not as dark as it was before.
that video really does not do the high gain channel any justice what so ever..the buzzsaw characteric is gone, the gain is a lot more usable now.
i'll try to make a better video this evening showing both channels.
great thing is the mod only takes 5 minutes to change, so you can swap back in forth between the tubes pretty fast...I also might install a switch behind the tubes that will allow me to switch resistors without needing to solder.
 
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