Startup Voltage Mod

[calmiswar]

Hello All,

Installed Speedball yesterday and things went really well. No problems whatsoever!
The sound seems to have tightened up a bit, the bass has definitely improved - I'm still getting acquainted, to be honest.

I know this question is beaten to death but please bear with me - I've been plugging in my headphones 30 secs after startup (I don't unplug when I turn the amp off) and I would ideally like to stop doing that and leave the headphones plugged in all the time. Every post on this topic links to a mod that is not longer available (dead link).

1. Should I just leave them plugged in?
2. If no, could someone please tell me about this mod to prevent DC surges at startup?

If it's any help, I use HD700s with the crack i.e. 150 Ohms impedance.

Thanks!

[borism]

I believe that if you built the new version - Crack 1.1 - as I id recently, the mod is already incorporated in the regular build instructions (page 35).

However, if you have an older Crack kit you may need to get some instructions (essentially connecting the 3 lugs on the headphone jack that are on the side away from the 9-pin socket).

I leave my HD 650s plugged in all the time.

[Chris65]

The mod was just to ground the unused tabs on the headphone jack.
I don't know why they removed that 'sticky' when the Crack 1.1 came out - likely still plenty of unbuilt, unmodified Crack 1.0's out there & this question has already popped up several times recently.

[calmiswar]

You guys are right, I've already done this. So should I be good? I mean, is it safe to leave my headphones plugged in since I have done the grounding?

Thanks.

[Paul Birkeland]

I will throw in that I bought HD-800's new that are in the first couple hundred ever made, and I've never bothered unplugging them when powering up my Crack.  There just isn't anything to be concerned about here, and I removed the post about the modification since it's built into the current kit.

-PB

[calmiswar]

I will throw in that I bought HD-800's new that are in the first couple hundred ever made, and I've never bothered unplugging them when powering up my Crack.  There just isn't anything to be concerned about here, and I removed the post about the modification since it's built into the current kit.

-PB

Thanks a lot PB.
It's just that ever since I destroyed my HD700s (because I had miswired the LEDs), I'm very apprehensive now.

Thanks again.

[calmiswar]

I will throw in that I bought HD-800's new that are in the first couple hundred ever made, and I've never bothered unplugging them when powering up my Crack.  There just isn't anything to be concerned about here, and I removed the post about the modification since it's built into the current kit.

-PB

Another question!
How do you like your HD800 with the Crack (I'm assuming it's speedballed)??

Thanks!

[Paul Birkeland]

It's just that ever since I destroyed my HD700s (because I had miswired the LEDs), I'm very apprehensive now.

What exactly happened here?  I'm not aware that improper installation of the LED's would cause such problems.  Additionally, not passing the voltage checks would be a sure consequence of not having the LED's in properly.

[calmiswar]

What exactly happened here?  I'm not aware that improper installation of the LED's would cause such problems.  Additionally, not passing the voltage checks would be a sure consequence of not having the LED's in properly.

Well, I had wired A8 LED to A7. I'm not even sure if both of them actually lit up, the voltage readings at 2 terminals were off. Still plugged the headphones in. So yes, I should probably get Headphonian Darwin Awards or something like that. Although, I have improved since then.

And if anyone else sees this, I'm turning the Crack + Speedball ON and OFF with the headphones plugged in. No problems.

Another question, should I worry if my LEDs just light up dimly and not brightly like some of the other LEDs in the circuit? The amp is proper though - great sound and no noise whatsoever.

[calmiswar]

Here's the original thread I created for this.
http://bottlehead.com/smf/index.php?topic=9782.0

[Paul Birkeland]

The LED's illuminate differently depending on the current being drawn through them. The four LED's on the bigger PC board should be the brightest, followed by the LED's on the 9 pin socket, and the LED's on the front PCB(s) will be the least bright.

[calmiswar]

The LED's illuminate differently depending on the current being drawn through them. The four LED's on the bigger PC board should be the brightest, followed by the LED's on the 9 pin socket, and the LED's on the front PCB(s) will be the least bright.

Great! That is exactly how mine is.