Resistance Check Questions

[networkn]

You're good to go.

14-40mV is 0.014-0.040V, which is nice and low.

Excellent thanks. Kicking myself as there were LED's in the Speedball kit I could have used instead of a resistor until my replacement arrives, however....

I do have a spare 10W10OhmJ Cement Resistor but I can't find any reference to it in the instructions nor parts list unless I am missing something?

[Paul Birkeland]

That must have snuck in the bag on accident, it is not used in the kit.

-PB

[networkn]

Hmm well I was very excited to have my first chance to listen today, after nearly 10 days since I completely finished!

Unfortunately something is very not right.

I can only hear from my left channel with my HD650's and there is a horrible buzz in that ear.

Also it appears that my volume was around the wrong way so my measurements were all taken with the device at full tilt, not sure if that should be of concern?

Not even sure where to start looking at this stage. I must admit I thought that when all the voltages were correct and resistance, that meant it was ready!

I am connecting from my PC via USB to an ODAC to the Crack via a 3.5mm to red and white rca and my HD650s are into the 6.5mm jack.

[networkn]

Ok well the plot thickens....

With the headphone fully inserted into the jack I can only hear one channel, and it sounds HORRIBLE, pull it out a little I can hear both channels but they aren't anywhere near as good as I imagined, something isn't right I am sure.

[Paul Birkeland]

If you pull the plug out slightly, you sum the channels and present the headphones with a mono signal.

Not having signal in one channel will likely present incorrect voltages, I'd remeasure and double check.

Otherwise, it's a missed solder joint, or a cooked headphone jack.

You can always post pics too, sometimes a miswire is easily spotted.

-PB

[networkn]

Hi There!

Startingly this weekend I have finally managed to get back to my crack. I have replied in this thread for historical reference, but if people prefer I can start a new thread.

I haven't touched it since MY last reply, but today I have powered it up to test it again and it's pretty much working fine, EXCEPT now there is a whine in the right hand cup of both my HE-500 and the HD-650's. It's not affected by the following:

1) Removing the Inputs from my DAC, or moving the cables around (twirling them in place)
2) Adjusting Volume.

It's relatively minor, but annoying nonetheless, there is also slight hiss, but I am not certain it's not the source. What is interesting is, that it's not always present.

Where do I start with troubleshooting the whine?

[networkn]

Hi There!

Startingly this weekend I have finally managed to get back to my crack. I have replied in this thread for historical reference, but if people prefer I can start a new thread.

I haven't touched it since MY last reply, but today I have powered it up to test it again and it's pretty much working fine, EXCEPT now there is a whine in the right hand cup of both my HE-500 and the HD-650's. It's not affected by the following:

1) Removing the Inputs from my DAC, or moving the cables around (twirling them in place)
2) Adjusting Volume.

It's relatively minor, but annoying nonetheless, there is also slight hiss, but I am not certain it's not the source. What is interesting is, that it's not always present.

Where do I start with troubleshooting the whine?

Interesting. Turned off the Amp and back on again, the HE-500's are fine. Unplugged the He-500 for the HD650's and now instead of a Whine both sides have a significant buzz. Can you not switch headphones like that?

Does it help locate the issue?

Also I am not sure if this is normal but the big Tube is HOT. The metal plate is warmish. My Infrared thermometer says it's 202 degrees Celcius (400F) which seems very hot. The little one shows at 66c (150F).

[Paul Birkeland]

Interesting. Turned off the Amp and back on again, the HE-500's are fine. Unplugged the He-500 for the HD650's and now instead of a Whine both sides have a significant buzz. Can you not switch headphones like that?

Does it help locate the issue?

Also I am not sure if this is normal but the big Tube is HOT. The metal plate is warmish. My Infrared thermometer says it's 202 degrees Celcius (400F) which seems very hot. The little one shows at 66c (150F).

This sure sounds like a loose connection or a bad solder joint that gets jostled around when you plug/unplug headphones.

Tubes do get hot.  If the metal plates on the inside glow red/orange hot, then there's an issue, but otherwise not.