Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Laudanum on March 27, 2020, 10:00:38 AM

Title: Voltage spike at turn on
Post by: Laudanum on March 27, 2020, 10:00:38 AM

I know that the voltage spike at turn-on is/was considered a non-issue.   Also know that there is/was a suggested mod to address it.   I built my Crack before the mod was mentioned and I've never done the mod to my amp.   Seeing how many of us, myself included are now experiencing way too much idle time, I was thinking of doing the mod for the hell of it.   Is the mod still suggested or has it been abandoned? 

Thanks 

Title: Re: Voltage spike at turn on
Post by: Paul Birkeland on March 27, 2020, 12:07:13 PM

This mod is now part of the Crack 1.1 kit, which is likely why there isn't much discussion on it currently.

-PB

Title: Re: Voltage spike at turn on
Post by: Laudanum on March 28, 2020, 05:01:52 AM

Quote from: Paul Birkeland on March 27, 2020, 12:07:13 PM

This mod is now part of the Crack 1.1 kit, which is likely why there isn't much discussion on it currently.

-PB

Thanks Paul.   Is there a link for or a photo of the mod?   I know it's simple but I don't have instructions for it.

Title: Re: Voltage spike at turn on
Post by: Paul Birkeland on March 28, 2020, 05:13:33 AM

On the Crack 1.0, there are two unused terminals on the headphone jack.  Run a wire through both, then connect it to the ground terminal where the black wire connects. 

Title: Re: Voltage spike at turn on
Post by: Laudanum on March 28, 2020, 05:23:33 AM

I just found a photo of the mod.  The resistors are positioned differently.    On my 1.0, one end of both  the 2.49K resistors are soldered to the bottom terminal on the side where the two terminals above it are unused.  But, I don't think I have to reposition the resistors.  Am I right in saying that I can leave those resistors where they are and simply solder a buss wire across the 3 terminals on that side of the jack? 

Thanks

Title: Re: Voltage spike at turn on
Post by: Paul Birkeland on March 28, 2020, 05:24:15 AM

You found a photo of the Crack 1.1. 

Yes, you can just solder wire connecting all three of the outboard terminals on the HP jack. 

Title: Re: Voltage spike at turn on
Post by: Laudanum on March 28, 2020, 07:10:28 AM

Well, that will take care of about 5 minutes of my day.   :D

Thanks Paul.

Title: Re: Voltage spike at turn on
Post by: Paul Birkeland on March 28, 2020, 07:26:01 AM

Yeah, now what?... ha ha

Title: Re: Voltage spike at turn on
Post by: sl-15 on April 16, 2020, 12:18:16 PM

Hi Paul,
I am going to hijack this thread for a related question rather then starting a new one. I just finished building a 2016 Crack (old version) and wired the headphone jack like it is now done in the Crack 1.1. Everything checked out and it sounds amazing with the exception of the headphone jack resistance. Terminal 6 and 10 measure 0 ohms instead of 2.4 kOhms. And my turn on voltage on the tip or ring stays 0 volts all through turn on.
Is this because the new 1.1 wiring scheme shunts the voltage to ground right away?
Thanks for clarifying. Best, Stefan

Title: Re: Voltage spike at turn on
Post by: Paul Birkeland on April 17, 2020, 06:24:21 AM

Yes, that's the purpose of the modification.

-PB