Bottlehead Forum

Bottlehead Kits => Kaiju Stereo 300B amp => Topic started by: oguinn on February 05, 2020, 07:33:36 AM

Title: Second set of pots
Post by: oguinn on February 05, 2020, 07:33:36 AM
I understand the pots behind the 300Bs are the hum pots. The others to the left and right of the 300Bs, though - what are those for? Are they only for the mono block conversion? What should I do with them if using the Kaiju not as a monoblock?
Title: Re: Second set of pots
Post by: oguinn on February 05, 2020, 08:10:45 AM
Ok, I spent a little more time searching and found that they're essentially balance pots. For reference for anyone looking for this information, I saw it in this thread (https://forum.bottlehead.com/index.php?topic=8619.msg82208#msg82208). Additionally turning them up is essentially the same as bypassing them, according to PB.

Search is your friend.
Title: Re: Second set of pots
Post by: Deke609 on February 05, 2020, 08:18:11 AM
Yeah, I believe they're for leveling signal strength of each channel. For example, if the left is just a bit stronger than the right (e.g., b/c of a difference between tubes), you can dial down the left to get the two channels to match.

IIRC, PB suggested to me somewhere on this forum that they can also permit you to boost the SNR of the BeePre (and presumably any other tube preamp): turn down the trim pots on the Kaiju and open up the attentuators on the Beepre. I *think* this increases the strength of the signal coming out the BP relative to the amp's noise floor. But if the noise is already part of the signal before reaching the BP, this won't help.

I keep my Kaiju trimpots fully open (or, more precisely, a degree or two of rotation under fully open - just as a precaution b/c I've noticed that some trim pots can act a little weird at their absolute extremes. But I haven't noticed any weird behavior from the Kaiju PEC pots.

cheers, Dderek
Title: Re: Second set of pots
Post by: oguinn on February 05, 2020, 08:20:37 AM
Oh cool, interesting. Thanks Derek. Finished before work today and have been checking it out between calls. Sounds really incredible!
Title: Re: Second set of pots
Post by: Deke609 on February 05, 2020, 08:28:24 AM
Sounds really incredible!

Yeah! I was surprised by how noticeably clearer and punchier the Kaiju was right off the bat as compared to my fully upgraded and fully burned in SII's. And it just gets better with a bit of tube and cap burn in (and/or "ear/brain burn-in" as some maintain).
Title: Re: Second set of pots
Post by: kgoss on February 05, 2020, 08:30:05 AM
The pots also allow you to use the amp with pretty much any preamp.  If you have a high gain preamp you can just turn down the level controls until you have the sweet spot between the amp and preamp.  This is essentially the same but more convenient and flexible than adding “padding resistors” to the Kaiju’s inputs.  Note the level controls are linear, not logarithmic.
Title: Re: Second set of pots
Post by: oguinn on February 05, 2020, 08:40:24 AM
Awesome, thanks for that Ken!
Title: Re: Second set of pots
Post by: Paul Joppa on February 05, 2020, 09:10:21 AM
The pots also allow you to use the amp with pretty much any preamp.  If you have a high gain preamp you can just turn down the level controls until you have the sweet spot between the amp and preamp.  This is essentially the same but more convenient and flexible than adding “padding resistors” to the Kaiju’s inputs.  Note the level controls are linear, not logarithmic.
Yes indeed. I put those pots into the Kaiju design partly because I use Paramounts, an old Foreplay III, and an Eros (both of which have higher than usual gain), and my speakers are pretty high efficiency. I have to use 24dB of external attenuators on each channel to get the preamp level controls past the first click.