Bogner Uberschall Rev 2 KT88 MOD?

[azzzy]

the bias pot while now a lot more sensitive (because "it" hasn't changed, but the amount of adjustability it's responsible for has)

Would it make sense to replace the bias pot as well? To match the wider bias range?

 

[Ventura]

the bias pot while now a lot more sensitive (because "it" hasn't changed, but the amount of adjustability it's responsible for has)

Would it make sense to replace the bias pot as well? To match the wider bias range?

Completely unnecessary. KISS - Keep It Simple Stoopid

 

[azzzy]

KISS - Keep It Simple Stoopid

Will do.

 

[DennisJr]

If my memory serves me correct it was the swap out of one of these resistors which were "matching" before.

Don't quote me on this - I've got the schematic of the "for sure" swap in my office but don't feel like drumming it up right now. However, all that aside - it's THAT simple.

Hope this helps.
Mo

Soooo I can't figure it out, but does anybody know or recognize this mod done to my Rev2 on the bias resistors???!!

 

[Ventura]

If my memory serves me correct it was the swap out of one of these resistors which were "matching" before.

Don't quote me on this - I've got the schematic of the "for sure" swap in my office but don't feel like drumming it up right now. However, all that aside - it's THAT simple.

Hope this helps.
Mo

Soooo I can't figure it out, but does anybody know or recognize this mod done to my Rev2 on the bias resistors???!!

Is that a parallel piggy back job or was the one underneath opened (removed) on the circuit? If it's connected it's in parallel and therefore it opened up the voltage regulated by the trim pot (which then translates into the current range to the tubes). Sum of the inverse of each individual resistor, as opposed to the sum of the actual resistors values.

 

[DennisJr]

If my memory serves me correct it was the swap out of one of these resistors which were "matching" before.

Don't quote me on this - I've got the schematic of the "for sure" swap in my office but don't feel like drumming it up right now. However, all that aside - it's THAT simple.

Hope this helps.
Mo

Soooo I can't figure it out, but does anybody know or recognize this mod done to my Rev2 on the bias resistors???!!

Is that a parallel piggy back job or was the one underneath opened (removed) on the circuit? If it's connected it's in parallel and therefore it opened up the voltage regulated by the trim pot (which then translates into the current range to the tubes). Sum of the inverse of each individual resistor, as opposed to the sum of the actual resistors values.

I think it is a parallel piggy back! I don't think the underneath resistor is open but I truly don't know.?. I am the second owner of this amp and I think this came from Bogner with this mod done to it from my understanding!? It's definitely interesting!!

 

[Ventura]

If my memory serves me correct it was the swap out of one of these resistors which were "matching" before.

Don't quote me on this - I've got the schematic of the "for sure" swap in my office but don't feel like drumming it up right now. However, all that aside - it's THAT simple.

Hope this helps.
Mo

Soooo I can't figure it out, but does anybody know or recognize this mod done to my Rev2 on the bias resistors???!!

Is that a parallel piggy back job or was the one underneath opened (removed) on the circuit? If it's connected it's in parallel and therefore it opened up the voltage regulated by the trim pot (which then translates into the current range to the tubes). Sum of the inverse of each individual resistor, as opposed to the sum of the actual resistors values.

I think it is a parallel piggy back! I don't think the underneath resistor is open but I truly don't know.?. I am the second owner of this amp and I think this came from Bogner with this mod done to it from my understanding!? It's definitely interesting!!

Seems to me they just opened the range up to accept 88/6550s. What's the pV and current you can get running through that amp in idle??

 

[DennisJr]

If my memory serves me correct it was the swap out of one of these resistors which were "matching" before.

Don't quote me on this - I've got the schematic of the "for sure" swap in my office but don't feel like drumming it up right now. However, all that aside - it's THAT simple.

Hope this helps.
Mo

Soooo I can't figure it out, but does anybody know or recognize this mod done to my Rev2 on the bias resistors???!!

Is that a parallel piggy back job or was the one underneath opened (removed) on the circuit? If it's connected it's in parallel and therefore it opened up the voltage regulated by the trim pot (which then translates into the current range to the tubes). Sum of the inverse of each individual resistor, as opposed to the sum of the actual resistors values.

I think it is a parallel piggy back! I don't think the underneath resistor is open but I truly don't know.?. I am the second owner of this amp and I think this came from Bogner with this mod done to it from my understanding!? It's definitely interesting!!

Seems to me they just opened the range up to accept 88/6550s. What's the pV and current you can get running through that amp in idle??

Hmm...I need to find out, I'm not sure...

 

[DennisJr]

You'll have to be patient with me haha I almost never have time to even play guitar, much less look at my amps! Lol

 

[Ventura]

^ Seems to me you've got time to play one helluva disco bling guitar in your sig

Wonder what the plate voltage of that guitar is

 

[DennisJr]

^ Seems to me you've got time to play one helluva disco bling guitar in your sig

Wonder what the plate voltage of that guitar is

Haha I'm the goofball in the background...and left my profile logged in on my phone and my wife made my signature...
I plan on checking the plate voltage and bias while I'm at it tomorrow, because I have the day off tomorrow. I PROMISE!! Lol

 

[maddnotez]

wow @Ventura

I completely missed your picture with the resistors circled.

 

[Ventura]

wow @Ventura

I completely missed your picture with the resistors circled.