Bad Tube

JVM Heads and Combos, Satriani 410HJS, Satriani Combo

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gainaddict
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Bad Tube

Postby gainaddict » 24 Aug 2017, 08:13

One of my JVM valves is going "Kaputt" on me.
I don't know which one - just hear a familiar "windy" noise which I recognize as a bad valve.
How can I diagnose which tube is bad and which tubes are you recommending for this amp?
Your help is appreciated.
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Re: Bad Tube

Postby Anitoli » 24 Aug 2017, 08:21

Windy noise is usually a microphonic preamp tube. Is this occurring on all channels?

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Re: Bad Tube

Postby gainaddict » 24 Aug 2017, 08:23

Anitoli wrote:Windy noise is usually a microphonic preamp tube. Is this occurring on all channels?

yes!
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Re: Bad Tube

Postby Anitoli » 24 Aug 2017, 08:31

Do you have a spare tube? Try changing out the phase inverter first. Excluding potential power tube noise, all Channels run through the Pi before hitting the power amp.

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Re: Bad Tube

Postby gainaddict » 24 Aug 2017, 09:16

Anitoli wrote:Do you have a spare tube? Try changing out the phase inverter first. Excluding potential power tube noise, all Channels run through the Pi before hitting the power amp.


No - I ought to order.
Should I buy JJ?
Should it be balanced?
It can be V1 too ain't so?
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Re: Bad Tube

Postby Roger » 24 Aug 2017, 09:28

Could be v1 too. I recomend replace all preamp tubes and then test the old valves which is the bad tube. After that you get 4 tubes for Spares.
Friend of mine loves his JVM 410 with tung sol tubes.
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Re: Bad Tube

Postby gainaddict » 24 Aug 2017, 09:45

Roger wrote:Could be v1 too. I recomend replace all preamp tubes and then test the old valves which is the bad tube. After that you get 3 tubes for Spares.
Friend of mine loves his JVM 410 with tung sol tubes.



Thanks.
I'd still like to hear Anitolis' opinion here.
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Re: Bad Tube

Postby Anitoli » 24 Aug 2017, 18:22

Don't worry about it being balanced, more money snake oil IMO. While i am not particular to JJ's, some do like them but any new production tube should be ok. If the signal to all channel runs through V1 then that could also be the suspect tube but it may be just as easy to replace all of them in one shot.

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Re: Bad Tube

Postby gainaddict » 25 Aug 2017, 03:11

Thanks P.
Replacing the pi tube + making sure that the el34s are firm in their sockets, did the trick.
The tone is subtantialy pleasant/clearer now.
More clarity to it for sure.
Didn't imagine that one preamp valve can make so much difference.
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Re: Bad Tube

Postby Anitoli » 25 Aug 2017, 06:55

Oh yeah it can. You get one that goes microphonic and that channel or amp becomes useless. It doesn't need to be old tubes either i have had new tubes go microphonic almost immediately after insertion.

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Re: Bad V1 Tube

Postby billy » 25 Aug 2017, 19:18

Good to know. Thanks, you guys.
---
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Re: Bad Tube

Postby gainaddict » 26 Aug 2017, 14:40

You're welcome!
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