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Re: BK Butler - Tube Driver

PostPosted: 28 May 2015, 19:07
by Bernardduur
Whaha, true!

BK Butler - Tube driver.JPG

Re: BK Butler - Tube Driver

PostPosted: 29 May 2015, 03:24
by tictac
Does anyone know about the "Bias Control" that's available as a new feature? According to Butler it controls the amount of current draw of the cathode.... You're supposed to be able to dial in the bias for different tube types....

Seems like it would be easy enough to implement... a pot between the cathode and V- perhaps? :hmmm:

TT

Re: BK Butler - Tube Driver

PostPosted: 29 May 2015, 03:40
by tictac
:oops: sorry for not doing a search first.... yep, it's a pot, Bajaman already drew up a nice schematic...

Funny cause I'm tinkering with my Bajaman tube driver after reading this thread just didnt realise he made some updates to the circuit... :slap:

TT

Re: BK Butler - Tube Driver

PostPosted: 29 May 2015, 17:07
by teemuk
tictac wrote:Does anyone know about the "Bias Control" that's available as a new feature?


In older TubeWorks units (e.g RT-902 Real Tube Rack) the "Bias" control was simply a potentiometer wired as variable cathode resistor.

Re: BK Butler - Tube Driver

PostPosted: 29 May 2015, 17:11
by teemuk
...oh, forgot to mention, quoted as being a feature that actually makes the distortion more tweakable and versatile.

Image
http://music-electronics-forum.com/atta ... e-rack.jpg

Re: BK Butler - Tube Driver

PostPosted: 27 May 2018, 06:09
by whopperplate
Thank you all for the wealth of info. I am working out the details for building one of these guys and I am I seeing correctly that only the hot is connected to the output jack, no ground? Is it connected via the input jack ground to chassis?

Another question, what would the effects be of increasing the drive and high pots from 500k to 1M? Some of the old pedals had this value and I am wondering about their tonal difference.

Thank you for the time!

Charlie

Re: BK Butler - Tube Driver

PostPosted: 27 May 2018, 07:43
by Dirk_Hendrik
Drive: Even more gain. About double of the max you had with a 500k pot. Tone: You'll change the frequency characteristic of the tone stack.

Re: BK Butler - Tube Driver

PostPosted: 27 May 2018, 12:21
by whopperplate
Dirk_Hendrik wrote:Drive: Even more gain. About double of the max you had with a 500k pot. Tone: You'll change the frequency characteristic of the tone stack.


Awesome, that’s what I was assuming more or less, thank you!

Does it shift the frequency response up or down? I have never been educated on the math of what’s going on. I appreciate all the help, thank you so much.

Charlie

Re: BK Butler - Tube Driver

PostPosted: 28 May 2018, 04:53
by whopperplate
Still most curious about the grounding scheme

Re: BK Butler - Tube Driver

PostPosted: 28 May 2018, 16:24
by whopperplate
Also from looking at the PCB photos it seems the red LED is wired with the cLED to ground after , rather then between the R16 and the LED as written in the schematic. can anyone please also confirm this? Thank you

Charlie