Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: jackhuman65 on May 14, 2020, 09:49:47 AM

Title: Speedball Voltage Issue [resolved]
Post by: jackhuman65 on May 14, 2020, 09:49:47 AM

I've installed the Speedball and I am getting slightly higher voltage on in two of the large board terminals than expected.  I am also getting non-zero voltages on terminals that should be zero.  Here are my measurements:

LARGE BOARD
OA (75-100V) 118V
OB (75-100V) 115V
G (0V) 5V
B+ (170-195V) 185V

SMALL BOARD
OA (60-90V) 93V
IA (170-270V) 180V
B-A/B (0V) 4V
IB (170-270V) 183V
OB (60-90V) 91V

All of my LEDs are lit, but the LEDs on the small board are dimmer and light a few seconds before the brighter LEDs on the large board.  Is the voltage issue one I should worry about?

Title: Re: Speedball Voltage Issue
Post by: Paul Birkeland on May 14, 2020, 10:08:20 AM

When you see 4V and 5V on those terminals that are supposed to be 0V, are you sure your meter isn't showing you 4mV and 5mV? (which would be 0.004V and 0.005V)

Your small board output voltages are slightly high, which is also driving up your large board output voltages.  That's probably nothing to be concerned about. 

Title: Re: Speedball Voltage Issue
Post by: jackhuman65 on May 14, 2020, 10:28:34 AM

I was measuring the voltage on the "600" DC setting on my multimeter.  When I switched it to the "200" setting, I am getting measurements more in line with what is expected. 

OA (75-100V) 112V
OB (75-100V) 113V
G (0V) .05V
B+ (170-195V) 177V

SMALL BOARD
OA (60-90V) 86V
IA (170-270V) 177V
B-A/B (0V) .05V
IB (170-270V) 177V
OB (60-90V) 86V

Any idea why they are now slightly lower?  Could this have any impact on the sound?  Perhaps I'm just losing my mind but I could swear that the music was less muddled when plugging my HD650s directly into my laptop as opposed to the Crack.

Title: Re: Speedball Voltage Issue
Post by: Paul Birkeland on May 14, 2020, 10:42:26 AM

It could be that the batteries in your meter are getting low, as that will do weird things.  Even the least expensive meter that is sometimes free at Harbor Freight is reasonably accurate. 

For muddled sound, I would suggest reflowing every solder joint in the amplifier.

Title: Re: Speedball Voltage Issue
Post by: jackhuman65 on May 15, 2020, 07:11:03 AM

I realized the sound issue was from a bad USB cable going from my laptop to my DAC.  Replaced the cable and everything sounds great.  Quite happy I don't need to re-solder anything.  Thanks for your help!