Confusion on speedball final voltage check at headphone jack

[keithpgdrb]

Finished my speedball upgrade, checked all the voltages and they seem fine.  went to the last step of checking the voltage at the headphone plug tip.  instructions say that it shouldn't go past 9V.  I swear mine is going to like 20+volts.  its only for a split second, but its going there.  how can this be when everything else checks out ok?  To show what I'm seeing, I've included a video of me turning on the crack with the probes in place.  also, here are my voltage readings, just in case I've gotten it wrong.  Help!!!

Video, that hopefully works.

Post

Voltage checks:


1. 87
2. 173
3. 0.8mv
4. 173
5. 89
6. 0
7. 110
8. 0
9. 109
10. 0
11. 0
12. 0
13. 172
14. 0
15. 192
16-
17-
18-
19. 80!!!! ok
20. 0
21. 210
A1. 88.6
A2. 0
A3. 1.53
A4. 0
A5. 0
A6. 86
A7. 0
A8. 1.5
A9. 0.9
B1  86
B2  172
B3  110
B4  88
B5  172
B6  109
B7  0
B8  0

[Chris65]

I think you're fine, if everything else checks out. With Speedball the mV reading tends to be higher on the TRS jack check.
Or just do the mod: http://www.bottlehead.com/smf/index.php/topic,2946.0.html

[keithpgdrb]

I was going to do that modification anyway.  that would solve my spike problem then?

[Doc B.]

It's OK. Those numbers aren't what really the headphones see. A 300 ohm headphone's impedance will lower the voltage by about a factor of 10.

[keithpgdrb]

So I can start listening to TUNES!!??!!  Sweet!  Thank you Doc.

[Doc B.]

Yeah, and if you are still concerned just turn the amp on first without headphones plugged in, wait a few seconds, then plug headphones in.

[keithpgdrb]

As long as you thnk the numbers are ok, I won't worry. Gonna add a few of your mods anyway n the week.  Looking forward to the tunes.