Tubes

[StingRay]

I have some tubes in my Jolida Dac, everything has been fine until the other evening, I switched the system on, started to play some music, very distorted then crackling, so tried a different track, same thing, there was no noise when music not playing.
So put in another Dac, SS, no problem. Switch tubes in Jolida, no problems, played several hours. Today, I thought I would give the first tubes another go, this time they played without any issues, only tried for a few minutes.

Any ideas what is going on?

 

[DUVET]

I have some tubes in my Jolida Dac, everything has been fine until the other evening, I switched the system on, started to play some music, very distorted then crackling, so tried a different track, same thing, there was no noise when music not playing.
So put in another Dac, SS, no problem. Switch tubes in Jolida, no problems, played several hours. Today, I thought I would give the first tubes another go, this time they played without any issues, only tried for a few minutes.

Any ideas what is going on?

I'd say they are on their way out . Like most hifi kit they like to give you hope before the fall.

 

[audio_PHIL_e]

Valves might misbehave, then start behaving properly after being moved. After that they may behave correctly for a random length of time then fail again when you least expect (or need) it. @DUVET is right. Have some replacements at the ready, and pray that when they fail, they don't take any other components with them (@rabski is that likely?)

 

[Fourlegs]

I have some tubes in my Jolida Dac, everything has been fine until the other evening, I switched the system on, started to play some music, very distorted then crackling, so tried a different track, same thing, there was no noise when music not playing.
So put in another Dac, SS, no problem. Switch tubes in Jolida, no problems, played several hours. Today, I thought I would give the first tubes another go, this time they played without any issues, only tried for a few minutes.

Any ideas what is going on?

It might just be the valve sockets. It is a good idea to periodically take the valves out and reinsert to make sure there is a good contact.

Or it might not be that at all.

 

[StingRay]

It might just be the valve sockets. It is a good idea to periodically take the valves out and reinsert to make sure there is a good contact.

Or it might not be that at all.

Thanks, but the contacts are very tight, so I doubt it would be that. I do swap them over from time to time.

 

[rabski]

Tight doesn't necessarily mean free of surface corrosion. There are nine pins there, so also 'tight' doesn't necessarily guarantee all of them are tight. It's worth cleaning the valve pins with a bit of fine sandpapaer (lightly).

It's a DAC, so the valves in the gain/buffer stage will be running relatively 'light' and the voltages and currents mean that even a drastic fail is unlikely to do any indicental damage.

Generally, a small signal valve failing will either be rapid and permanent (and obvious), or a gradual degradation. Distortion and crackling that stops when you swap valves around does suggest poor contacts, and that's not at all unusual. I'd give 'em a good clean and then keep an eye (ear) on it.

Worst comes to worst, you've got spares.

 

[m7rso]

Put them in, take them out, in out in out, shake them all about. I do that intermittently..not shaking..

 

[pmcuk]

I always recommend a fibreglass pencil for cleaning metal. Works like a charm. I use it all the time, especially cleaning metal before soldering. Useful on valve pins. For sockets you could use interdental brushes with acetone maybe. I don't usually bother.

https://cpc.farnell.com/unbranded/10191/fibreglass-pencil-4mm/dp/SABU10191?st=fibreglass pen

 

[rabski]

I always recommend a fibreglass pencil for cleaning metal. Works like a charm. I use it all the time, especially cleaning metal before soldering. Useful on valve pins. For sockets you could use interdental brushes with acetone maybe. I don't usually bother.

https://cpc.farnell.com/unbranded/10191/fibreglass-pencil-4mm/dp/SABU10191?st=fibreglass pen

Good shout that.

Incidentally, I have a (possibly irrational) personal hatred of so-called contact cleaners. Especially spray ones. Anything capable of chemically removing corrostion has no place near some other components, and a lot that I've seen leave a residue that ends up actually collecting dirt and debris.

Maybe a tiny bit of deoxit on a cotton bud in valve sockets, but best of all, just use something dry to clean.

 

[StingRay]

Tight doesn't necessarily mean free of surface corrosion. There are nine pins there, so also 'tight' doesn't necessarily guarantee all of them are tight. It's worth cleaning the valve pins with a bit of fine sandpapaer (lightly).

It's a DAC, so the valves in the gain/buffer stage will be running relatively 'light' and the voltages and currents mean that even a drastic fail is unlikely to do any indicental damage.

Generally, a small signal valve failing will either be rapid and permanent (and obvious), or a gradual degradation. Distortion and crackling that stops when you swap valves around does suggest poor contacts, and that's not at all unusual. I'd give 'em a good clean and then keep an eye (ear) on it.

Worst comes to worst, you've got spares.

OK thanks, I will have a close look at them and clean them up. Yes I have spares but these are the most expensive pair and almost impossible to replace now.