Vincent PHO-700 Phono Stage clicking on and off

tvham

tvham

Well-Known Member
Here's a weird one for the group - my Vincent PHO-700 Phono Stage will random click on and off (power light and tube are still lit up) from time to time. Sometimes I'll manually power it off then back on again and it will work just fine, other times it will click back on before I can even toggle the on/off switch.
It happens at random times - sometimes I'll play records for hours and it will never happen, other times it will happen numerous times on my first listen of an album.

Is this a sign that I need a new tube? Or is the fact that the fuse is still lit up a sign that it's something else? I bought it used 3 years ago and have never replaced the tube.
 
tvham said:
Here's a weird one for the group - my Vincent PHO-700 Phono Stage will random click on and off (power light and tube are still lit up) from time to time. Sometimes I'll manually power it off then back on again and it will work just fine, other times it will click back on before I can even toggle the on/off switch.
It happens at random times - sometimes I'll play records for hours and it will never happen, other times it will happen numerous times on my first listen of an album.

Is this a sign that I need a new tube? Or is the fact that the fuse is still lit up a sign that it's something else? I bought it used 3 years ago and have never replaced the tube.
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That sounds random and worrying.

With small signal tubes generally the sign they are done is a decrease in sound quality and occasionally a bit of fuzz or interference akin to a defined radio. They can often last upwards of 4 years.
 
For some information, I was the prior owner of this unit and replaced the tube in 2019.

It is:

Electro-Harmonix 12AU7 EH Preamp Vacuum Tube

Low Noise & Microphonics: $4.00 x 1
Balanced Triodes: $2.00 x 1
 
wmeugene said:
I know I’d always turn the phono on first as that’s what the instructions say.
Click to expand...

Yes you always start turning on with the source in order and off with the integrated/power amplifier in reverse order.

That is generally to protect your speakers and any fancy tube amplifiers from pops or current surges from phono stages and preamplifiers.
 
wmeugene said:
Since it has been six years on the tube, I’d probably try that since it is a relatively cheap thing to try.

I know I’d always turn the phono on first as that’s what the instructions say.
Click to expand...

Joe Mac said:
Yes you always start turning on with the source in order and off with the integrated/power amplifier in reverse order.

That is generally to protect your speakers and any fancy tube amplifiers from pops or current surges from phono stages and preamplifiers.
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yeah, I always turn it on first and wait to hear that it's 'on' before turning on my integrated amp. I think I'll try a new tube before panicking too much...the weird thing is this has happened for many months (over a year?) and aside randomly shutting off it's worked perfectly!
 
tvham said:
I saw this tube recommended...do you have any thoughts on it?

Click to expand...

I have a set of their other 12AU7 offering for my power amps that I use as drivers and have heard other JJ tubes in the past. They’re grand and mostly reliable so long as you use a reputable tube dealer. The key with tubes is don’t shoot for the deal, use a reputable specialist even if it’s a bit more expensive. With that one triode tube using different sides of itself to do each channel make sure to get a balanced tube.
 
Joe Mac said:
I have a set of their other 12AU7 offering for my power amps that I use as drivers and have heard other JJ tubes in the past. They’re grand and mostly reliable so long as you use a reputable tube dealer. The key with tubes is don’t shoot for the deal, use a reputable specialist even if it’s a bit more expensive. With that one triode tube using different sides of itself to do each channel make sure to get a balanced tube.
Click to expand...
Eh, sorry for the newb question but what do you mean by balanced tube? It's just one tube but you're saying make sure it's quality from a good dealer?
 
tvham said:
Eh, sorry for the newb question but what do you mean by balanced tube? It's just one tube but you're saying make sure it's quality from a good dealer?
Click to expand...

So with a triode tube like this it has 2 sides. Say in my power amplifier it has multiple tubes 3 for left and 3 for right so the two sides of the triode tube don’t need to be balanced. On this phono and on the new one I have coming it is using both sides of the triode for different channels, one side left and one side right. It is important in that scenario that both sides of the triode are balanced off against each other so that you’re getting the same gain on each channel. A reputable tube dealer will offer the option to have a small signal tube like this one so balanced.
 
Joe Mac said:
So with a triode tube like this it has 2 sides. Say in my power amplifier it has multiple tubes 3 for left and 3 for right so the two sides of the triode tube don’t need to be balanced. On this phono and on the new one I have coming it is using both sides of the triode for different channels, one side left and one side right. It is important in that scenario that both sides of the triode are balanced off against each other so that you’re getting the same gain on each channel. A reputable tube dealer will offer the option to have a small signal tube like this one so balanced.
Click to expand...
Makes sense, thanks
 
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