Is this tube okay?

[Korvanjund]

I have had a blackstar ht5c for a while now (purchased second hand) and I've just opened it open for the first time to see the condition of the tubes. One 12BH7 and one 12AX7. Both preamp tubes. However the tip of the 12BH7 seems to be cracked off. The amp has always worked but I want to know if this would affect the sound at all. I'm fairly averse to buying new tubes as I didn't pay much for the amp but if I need to I will.

 

[Demanic]

Re: Is this tube okay?

If the tube were bad, the amp would either sound horrible or make no sound at all.

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[Gtrjunior]

Re: Is this tube okay?

A preamp tube costs less than $20. I’d just buy a new one.

 

[Demanic]

Re: Is this tube okay?

A preamp tube costs less than $20. I’d just buy a new one.

This.
Though, if the break on the top of the tube had contaminated the vacuum, I think that the tube would have already died. The filliments would have oxidised and the tube would look cloudy. Plus, no sound.

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[Gtrjunior]

Re: Is this tube okay?

This.
Though, if the break on the top of the tube had contaminated the vacuum, I think that the tube would have already died. The filliments would have oxidised and the tube would look cloudy. Plus, no sound.

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Absolutely. You’re on point with that assessment.
But peace of mind for $20 is worth it to me.

 

[saxmo]

Re: Is this tube okay?

The tube is fine. If it ain't broke,don't fix it. Buy a spare, but you'll probably never need it.

 

[Korvanjund]

Re: Is this tube okay?

OK, thanks

 

[evan47]

Re: Is this tube okay?

I just acquired a blackstar HT Dual pedal and the first thing I did was change the tube from the original sovtek to a jj ecc83s gold pin ((keeping the sovtek as a spare).
I found the original tube to harsher and more brittle in its sound when compared to the jj which is smoother and more pleasant.
It would not hurt to change the tubes and keep the old ones as spares as preamp tubes are relatively cheap and the difference it can make can be worth the cost and effort.

 

[Zombiwoof]

Re: Is this tube okay?

Is the 12BH7 in a slot made for a 12AX7?. The 12BZ7 is the larger version of a 12AX7, I think the 12BH7 is a lower gain tube, but off the top of my head I don't know the gain of that tube.
Al

 

[Darg1911]

Re: Is this tube okay?

Pretty sure that the 12BH7 is the power tube in that amp. 12AX7 preamp. But yeah, 12BH7 is closer to a 12AU7. I think it draws double the plate current, or close to it. I have a headphone amp that uses a 12AU7 as the driver but the PT can supply the needed current for the 12BH7.

At any rate, always a good idea to have spares on hand as I think others have mentioned here.
I think there is a current production 12BH7 from EHX. But some of the NOS tubes can still be had for not too much money.