Crack with Speedball - no audio from left channel, right channel very faint

[casctu]

Hi guys,

I built the Crack back in 2014, and needed some assistance to get it working correctly, but with some help from Caucasian Backplate (https://bottlehead.com/smf/index.php?topic=6163.0), I was able to get it up and running, and it sounded great.

I installed the Speedball less than a month later, encountered no further problems, and have been enjoying great music ever since. There really is a noticeable difference after installing the Speedball.

Yesterday, out of the blue, I am getting no audio out of the left channel, and a hum can be heard constantly out of both channels. There is audio from the right channel, but it is very faint and muddy. I confirmed it wasn't an issue with my PC by connecting my FiiO X5 directly to the Crack, and the same thing occurs.

I have not made changes to the Crack since I installed the Speedball, it has not taken any fall damage or anything like that, and has been working great for years. Is it possible the 5963 or RCA 6080 need to be replaced?

Both still light up when the Crack is powered on, but they have seen regular use for years. What do you guys think?

[Paul Birkeland]

I would do a voltage check and let us know what you find.

It's very rare for a tube to just quit working all together randomly one day.  Generally when they wear out, they sound terrible and garbled long before they stop passing signal.

-PB

[casctu]

Thanks for the prompt reply

Thinking about the situation some more, I think I may have some more insight into what went wrong.

A little background, which I had completely forgotten about when I originally posted:

About a year ago, when bringing the Crack to another location, the 5963 tube ended up getting bumped by something, and was pushed to the side while connected to the Crack. I took the tube out and the pins were all slightly bent to the left. I was able to straighten them out over time, but some time after that point, I noticed that after I had been listening to music for 15 minutes or so, the audio become less clear. In the process of troubleshooting, I noticed that if I moved the 5963 tube around a bit, the audio would clear up and the issue would go away. Since that time, every time the audio becomes "muddy", I would slightly move the 5963 around and it would correct the problem.

After posting this issue on the forum today, I was experimenting, and when moving the 5963 around, instead of correcting the issue, I hear a loud pop/crack noise in the left channel. Of course, that immediately dissuaded me from continuing any further. That said, I somehow ended up positioning the 5963 in just the right way, so both audio channels are now playing at normal volume (maybe even louder, if I'm not crazy?), and the issue I mentioned earlier where the audio becomes "muddy" after 15 minutes is gone. Could have been that when removing the tubes to get a better look at the model/brand, the pins were realigned.

My follow up question is - should I ever be moving the 5963 around while the Crack is running for any reason, and if so, is it okay that when I do so now, it makes a loud pop/crack noise from the left channel? Now that I have the 5963 positioned just right, of course, I'm not going to move it around any more, at least not intentionally.

If you feel that checking the voltages in this case would still be useful, let me know, and I will take the measurements. Either way, now that the 5963 is better aligned in the slot, my Crack is working better than it ever has with my current setup.

[Paul Birkeland]

I suspect you have a faulty solder joint on the 9 pin socket.   It seems very likely that it's the center pin, but in any event, I would consider your amplifier still to be in need of repair. 

[casctu]

It's been quite a while since I have soldered anything, but I tried to reflow the center pin, and it is still behaving the same way; it works great as long as I don't touch the 5963. Could be the reflow didn't work because I am out of practice, or as you said, it could have been one of the other solder joints.

I've attached a couple of images of the 9-pin area after I attempted to reflow the center pin. I think I'm going to set aside some time to practice my soldering again, and give it another shot once I'm back up to snuff.

Based on the images, would you reflow all of the solder joints on the 9-pin section?

[adydula]

Does one of the leds go on and off with the wiggling on the tube?

Alex

[casctu]

Does one of the leds go on and off with the wiggling on the tube?

Alex

Yes, the LED connected to A3 goes out when the 5963 tube is moved. All other LEDs remain lit.

[adydula]

This happened to me awhile back when I was changing out several tubes to find "audio nirvana".....  I found that soldering these leds on the socket without any "bend" for some stress relief mechanically broke the leds....these tiny plasticy leds dont seem to take much tugging or movement if soldered in without any strain relief....

I replaced both of my leds and bent them upslighty to allow for somr strain relief....

Been ok for almost a year now, and be careful wiggling tubes in and out of the socket....go slow and try not to rock the tube side to side excessively....

Good luck!

Alex

[Paul Birkeland]

A5 is not adequately flowed.