Tube amp maintenance

It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO. Do
tubes give any subtle warnings as they approach death, or does it tend to be
sudden?

"JoeSpareBedroom" <dishborealis@yahoo.com> writes:

> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO. Do
> tubes give any subtle warnings as they approach death, or does it tend to be
> sudden?

Things slowly start sounding like crap, noisy, gone microphonic,
distorting more, etc.

I've not run into a sudden outage, but my tube amp experience is
relatively limited.

--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette |
/ \ http://www.toddh.net/netiquette/ | http://myspace.com/bmiawmb

JoeSpareBedroom wrote:
> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO. Do
> tubes give any subtle warnings as they approach death, or does it tend to be
> sudden?

Both. Sometimes it's gradual and they just start to sound like crap
(I was going to post this and then noticed Todd used the exact words I
was going to use). The normal thing is they loose what is called
"emission" It's what a tube checker tests. Typically that also means
the gain gets low as well though only the high end tube testers check
gain. Emission is the ability of the cathode to emit electrons. As a
tube ages that ability sort of fades. That is the "normal" failure
mode.

Also they can become "microphonic". That means one or more of the
elements in the tube has broken loose and is wiggling. If you tap on
the tube you can hear it in the amp.

They also can develop gas. Especially true of power tubes. Usually you
can tell if there is a blue glow in the tube. Testers often check for
gas. Gas or low emission can cause the bias point of the tube to
shift which then ends up with the plates glowing red. NOT a good
sign.

Then there are the "sudden death" failures. The most common one is
that the heater fails. The tube quite simply won't "light up". You'll
have no "glow" of the cathode. A short also can be a sudden failure.
Tube testers can show these faults too.

If you can find someone with a tube tester that is the best way. This
is why even old junker tube testers that used to be trash seem to be
going for big bucks these days!

"Benj" <bjacoby@iwaynet.net> wrote in message
news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
>
>
> JoeSpareBedroom wrote:
>> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO.
>> Do
>> tubes give any subtle warnings as they approach death, or does it tend to
>> be
>> sudden?
>
> Both. Sometimes it's gradual and they just start to sound like crap
> (I was going to post this and then noticed Todd used the exact words I
> was going to use). The normal thing is they loose what is called
> "emission" It's what a tube checker tests. Typically that also means
> the gain gets low as well though only the high end tube testers check
> gain. Emission is the ability of the cathode to emit electrons. As a
> tube ages that ability sort of fades. That is the "normal" failure
> mode.
>
> Also they can become "microphonic". That means one or more of the
> elements in the tube has broken loose and is wiggling. If you tap on
> the tube you can hear it in the amp.
>
> They also can develop gas. Especially true of power tubes. Usually you
> can tell if there is a blue glow in the tube. Testers often check for
> gas. Gas or low emission can cause the bias point of the tube to
> shift which then ends up with the plates glowing red. NOT a good
> sign.
>
> Then there are the "sudden death" failures. The most common one is
> that the heater fails. The tube quite simply won't "light up". You'll
> have no "glow" of the cathode. A short also can be a sudden failure.
> Tube testers can show these faults too.
>
> If you can find someone with a tube tester that is the best way. This
> is why even old junker tube testers that used to be trash seem to be
> going for big bucks these days!
>
>


So, let's say you use the thing for 15-20 hours a week. What's a good time
frame to replace all the tubes? In the case of the Ampeg, we're talking only
preamp stage tubes.

JoeSpareBedroom <dishborealis@yahoo.com> wrote:
> "Benj" <bjacoby@iwaynet.net> wrote in message
>
news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
>>
>>
>> JoeSpareBedroom wrote:
>>> It's that time again. New amp, probably either an SVT-3PRO or
>>> SVT-4PRO. Do
>>> tubes give any subtle warnings as they approach death, or does it
>>> tend to be
>>> sudden?
>>
>> Both. Sometimes it's gradual and they just start to sound like crap
>> (I was going to post this and then noticed Todd used the exact words
>> I was going to use). The normal thing is they loose what is called
>> "emission" It's what a tube checker tests. Typically that also means
>> the gain gets low as well though only the high end tube testers check
>> gain. Emission is the ability of the cathode to emit electrons. As a
>> tube ages that ability sort of fades. That is the "normal" failure
>> mode.
>>
>> Also they can become "microphonic". That means one or more of the
>> elements in the tube has broken loose and is wiggling. If you tap on
>> the tube you can hear it in the amp.
>>
>> They also can develop gas. Especially true of power tubes. Usually
>> you can tell if there is a blue glow in the tube. Testers often
>> check for gas. Gas or low emission can cause the bias point of the
>> tube to shift which then ends up with the plates glowing red. NOT a
>> good sign.
>>
>> Then there are the "sudden death" failures. The most common one is
>> that the heater fails. The tube quite simply won't "light up".
>> You'll have no "glow" of the cathode. A short also can be a sudden
>> failure. Tube testers can show these faults too.
>>
>> If you can find someone with a tube tester that is the best way.
>> This is why even old junker tube testers that used to be trash seem
>> to be going for big bucks these days!
>>
>>
>
>
> So, let's say you use the thing for 15-20 hours a week. What's a good
> time frame to replace all the tubes? In the case of the Ampeg, we're
> talking only preamp stage tubes.

I don't think it's necessary (or even wise) to have a regular
replacement schedule. The sudden burnouts occur seldom, and tube life
varies over orders of magnitude depending on brand, type, date of
manufacture, etc.

Four out of the five tubes in my SVT-3 are 12AX7s which are the most
common preamp tubes in guitar and bass amps. The other one is a 12AU7.
Keep spares of both handy. Unlike power tubes, they can be just swapped
in and need no biasing.

"RichL" <rpleavitt@yahoo.com> wrote in message
news:Vi2Xj.1079$vE.7@trnddc03...
> JoeSpareBedroom <dishborealis@yahoo.com> wrote:
>> "Benj" <bjacoby@iwaynet.net> wrote in message
>>
> news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
>>>
>>>
>>> JoeSpareBedroom wrote:
>>>> It's that time again. New amp, probably either an SVT-3PRO or
>>>> SVT-4PRO. Do
>>>> tubes give any subtle warnings as they approach death, or does it
>>>> tend to be
>>>> sudden?
>>>
>>> Both. Sometimes it's gradual and they just start to sound like crap
>>> (I was going to post this and then noticed Todd used the exact words
>>> I was going to use). The normal thing is they loose what is called
>>> "emission" It's what a tube checker tests. Typically that also means
>>> the gain gets low as well though only the high end tube testers check
>>> gain. Emission is the ability of the cathode to emit electrons. As a
>>> tube ages that ability sort of fades. That is the "normal" failure
>>> mode.
>>>
>>> Also they can become "microphonic". That means one or more of the
>>> elements in the tube has broken loose and is wiggling. If you tap on
>>> the tube you can hear it in the amp.
>>>
>>> They also can develop gas. Especially true of power tubes. Usually
>>> you can tell if there is a blue glow in the tube. Testers often
>>> check for gas. Gas or low emission can cause the bias point of the
>>> tube to shift which then ends up with the plates glowing red. NOT a
>>> good sign.
>>>
>>> Then there are the "sudden death" failures. The most common one is
>>> that the heater fails. The tube quite simply won't "light up".
>>> You'll have no "glow" of the cathode. A short also can be a sudden
>>> failure. Tube testers can show these faults too.
>>>
>>> If you can find someone with a tube tester that is the best way.
>>> This is why even old junker tube testers that used to be trash seem
>>> to be going for big bucks these days!
>>>
>>>
>>
>>
>> So, let's say you use the thing for 15-20 hours a week. What's a good
>> time frame to replace all the tubes? In the case of the Ampeg, we're
>> talking only preamp stage tubes.
>
> I don't think it's necessary (or even wise) to have a regular
> replacement schedule. The sudden burnouts occur seldom, and tube life
> varies over orders of magnitude depending on brand, type, date of
> manufacture, etc.
>
> Four out of the five tubes in my SVT-3 are 12AX7s which are the most
> common preamp tubes in guitar and bass amps. The other one is a 12AU7.
> Keep spares of both handy. Unlike power tubes, they can be just swapped
> in and need no biasing.
>
>


How do you like your SVT-3?

JoeSpareBedroom <dishborealis@yahoo.com> wrote:
> "RichL" <rpleavitt@yahoo.com> wrote in message
> news:Vi2Xj.1079$vE.7@trnddc03...
>> JoeSpareBedroom <dishborealis@yahoo.com> wrote:
>>> "Benj" <bjacoby@iwaynet.net> wrote in message
>>>
>>
news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
>>>>
>>>>
>>>> JoeSpareBedroom wrote:
>>>>> It's that time again. New amp, probably either an SVT-3PRO or
>>>>> SVT-4PRO. Do
>>>>> tubes give any subtle warnings as they approach death, or does it
>>>>> tend to be
>>>>> sudden?
>>>>
>>>> Both. Sometimes it's gradual and they just start to sound like
>>>> crap (I was going to post this and then noticed Todd used the
>>>> exact words I was going to use). The normal thing is they loose
>>>> what is called "emission" It's what a tube checker tests.
>>>> Typically that also means the gain gets low as well though only
>>>> the high end tube testers check gain. Emission is the ability of
>>>> the cathode to emit electrons. As a tube ages that ability sort of
>>>> fades. That is the "normal" failure mode.
>>>>
>>>> Also they can become "microphonic". That means one or more of the
>>>> elements in the tube has broken loose and is wiggling. If you tap
>>>> on the tube you can hear it in the amp.
>>>>
>>>> They also can develop gas. Especially true of power tubes. Usually
>>>> you can tell if there is a blue glow in the tube. Testers often
>>>> check for gas. Gas or low emission can cause the bias point of the
>>>> tube to shift which then ends up with the plates glowing red. NOT a
>>>> good sign.
>>>>
>>>> Then there are the "sudden death" failures. The most common one is
>>>> that the heater fails. The tube quite simply won't "light up".
>>>> You'll have no "glow" of the cathode. A short also can be a sudden
>>>> failure. Tube testers can show these faults too.
>>>>
>>>> If you can find someone with a tube tester that is the best way.
>>>> This is why even old junker tube testers that used to be trash seem
>>>> to be going for big bucks these days!
>>>>
>>>>
>>>
>>>
>>> So, let's say you use the thing for 15-20 hours a week. What's a
>>> good time frame to replace all the tubes? In the case of the Ampeg,
>>> we're talking only preamp stage tubes.
>>
>> I don't think it's necessary (or even wise) to have a regular
>> replacement schedule. The sudden burnouts occur seldom, and tube
>> life varies over orders of magnitude depending on brand, type, date
>> of manufacture, etc.
>>
>> Four out of the five tubes in my SVT-3 are 12AX7s which are the most
>> common preamp tubes in guitar and bass amps. The other one is a
>> 12AU7. Keep spares of both handy. Unlike power tubes, they can be
>> just swapped in and need no biasing.
>>
>>
>
>
> How do you like your SVT-3?

Love it!
Caveats: (1) I'm primarily a guitarist, not a bassist; (2) when I
record bass, it's usually going directly to a preamp and then into the
computer; (3) I don't gig any more. So it doesn't get a hell of a lot
of use. But I don't have the urge to get another bass amp, although a
few more basses are on my list. That amp does everything I want and
more.

I'm running it through an SVT-410H cabinet. I usually run that cab with
the horn disabled. I picked them both up used about 2 years ago.

<<Unlike power tubes, they can be just swapped in and need no
biasing.>>

You can bias the Power tubes yourself on the Classic.

"JoeSpareBedroom" <dishborealis@yahoo.com> wrote in message
news:a22Xj.143$xb2.68@fe103.usenetserver.com...
> "Benj" <bjacoby@iwaynet.net> wrote in message
> news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
>>
>>
>> JoeSpareBedroom wrote:
>>> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO.
>>> Do
>>> tubes give any subtle warnings as they approach death, or does it tend
>>> to be
>>> sudden?
>>
>> Both. Sometimes it's gradual and they just start to sound like crap
>> (I was going to post this and then noticed Todd used the exact words I
>> was going to use). The normal thing is they loose what is called
>> "emission" It's what a tube checker tests. Typically that also means
>> the gain gets low as well though only the high end tube testers check
>> gain. Emission is the ability of the cathode to emit electrons. As a
>> tube ages that ability sort of fades. That is the "normal" failure
>> mode.
>>
>> Also they can become "microphonic". That means one or more of the
>> elements in the tube has broken loose and is wiggling. If you tap on
>> the tube you can hear it in the amp.
>>
>> They also can develop gas. Especially true of power tubes. Usually you
>> can tell if there is a blue glow in the tube. Testers often check for
>> gas. Gas or low emission can cause the bias point of the tube to
>> shift which then ends up with the plates glowing red. NOT a good
>> sign.
>>
>> Then there are the "sudden death" failures. The most common one is
>> that the heater fails. The tube quite simply won't "light up". You'll
>> have no "glow" of the cathode. A short also can be a sudden failure.
>> Tube testers can show these faults too.
>>
>> If you can find someone with a tube tester that is the best way. This
>> is why even old junker tube testers that used to be trash seem to be
>> going for big bucks these days!
>>
>>
>
>
> So, let's say you use the thing for 15-20 hours a week. What's a good time
> frame to replace all the tubes? In the case of the Ampeg, we're talking
> only preamp stage tubes.

Preamp tubes don't dissipate power like the power tubes
and usually last for years. I have an SWR amp with
a preamp tube stage and have changed it only once
in 16 years. Even that may have been a red herring
(intermittent problem that eventually turned out to be
a loose jack).

- Gary Rosen

Gary Rosen wrote:
>
> "JoeSpareBedroom" <dishborealis@yahoo.com> wrote in message
> news:a22Xj.143$xb2.68@fe103.usenetserver.com...
> > "Benj" <bjacoby@iwaynet.net> wrote in message
> > news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
> >>
> >>
> >> JoeSpareBedroom wrote:
> >>> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO.
> >>> Do
> >>> tubes give any subtle warnings as they approach death, or does it tend
> >>> to be
> >>> sudden?
> >>
> >> Both. Sometimes it's gradual and they just start to sound like crap
> >> (I was going to post this and then noticed Todd used the exact words I
> >> was going to use). The normal thing is they loose what is called
> >> "emission" It's what a tube checker tests. Typically that also means
> >> the gain gets low as well though only the high end tube testers check
> >> gain. Emission is the ability of the cathode to emit electrons. As a
> >> tube ages that ability sort of fades. That is the "normal" failure
> >> mode.
> >>
> >> Also they can become "microphonic". That means one or more of the
> >> elements in the tube has broken loose and is wiggling. If you tap on
> >> the tube you can hear it in the amp.
> >>
> >> They also can develop gas. Especially true of power tubes. Usually you
> >> can tell if there is a blue glow in the tube. Testers often check for
> >> gas. Gas or low emission can cause the bias point of the tube to
> >> shift which then ends up with the plates glowing red. NOT a good
> >> sign.
> >>
> >> Then there are the "sudden death" failures. The most common one is
> >> that the heater fails. The tube quite simply won't "light up". You'll
> >> have no "glow" of the cathode. A short also can be a sudden failure.
> >> Tube testers can show these faults too.
> >>
> >> If you can find someone with a tube tester that is the best way. This
> >> is why even old junker tube testers that used to be trash seem to be
> >> going for big bucks these days!
> >>
> >>
> >
> >
> > So, let's say you use the thing for 15-20 hours a week. What's a good time
> > frame to replace all the tubes? In the case of the Ampeg, we're talking
> > only preamp stage tubes.
>
> Preamp tubes don't dissipate power like the power tubes
> and usually last for years. I have an SWR amp with
> a preamp tube stage and have changed it only once
> in 16 years. Even that may have been a red herring
> (intermittent problem that eventually turned out to be
> a loose jack).
>
> - Gary Rosen

I'd just like to add to Gary's experience.

Many times I've had vintage amps come in my shop with some of the original factory branded tubes
made by the big four USA tube companies still in them.

Some of them over 35+ years old. Then, you compare them to a few NOS tubes and you find you can
hardly detect a difference.

That kind of long distance performance has yet to be witnessed by the tubes commonly used from off
shore.

With power tubes, it's a bit similar. But, with a shorter life expectancy.

Microphonics can occur in both, and it's best to not put your tube in/on a place of vibration.

Vibrating the tubes does invite microphonics.

Combo amps are a tube killer.



Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers

On May 15, 2:30 pm, "JoeSpareBedroom" <dishborea...@yahoo.com> wrote:
> "Benj" <bjac...@iwaynet.net> wrote in message
>
> news:ad7c7934-986d-44ea-a23b-47798ae0c967@c65g2000hsa.googlegroups.com...
>
>
>
>
>
>
>
> > JoeSpareBedroom wrote:
> >> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO.=

> >> Do
> >> tubes give any subtle warnings as they approach death, or does it tend =
to
> >> be
> >> sudden?
>
> > Both.  Sometimes it's gradual and they just start to sound like crap
> > (I was going to post this and then noticed Todd used the exact words I
> > was going to use). The normal thing is they loose what is called
> > "emission" It's what a tube checker tests.  Typically that also means
> > the gain gets low as well though only the high end tube testers check
> > gain.  Emission is the ability of the cathode to emit electrons. As a
> > tube ages that ability sort of fades.  That is the "normal" failure
> > mode.
>
> > Also they can become "microphonic". That means one or more of the
> > elements in the tube has broken loose and is wiggling. If you tap on
> > the tube you can hear it in the amp.
>
> > They also can develop gas. Especially true of power tubes. Usually you
> > can tell if there is a blue glow in the tube. Testers often check for
> > gas.  Gas or low emission can cause the bias point of the tube to
> > shift which then ends up with the plates glowing red. NOT a good
> > sign.
>
> > Then there are the "sudden death" failures. The most common one is
> > that the heater fails.  The tube quite simply won't "light up". You'll=

> > have no "glow" of the cathode. A short also can be a sudden failure.
> > Tube testers can show these faults too.
>
> > If you can find someone with a tube tester that is the best way.  This=

> > is why even old junker tube testers that used to be trash seem to be
> > going for big bucks these days!
>
> So, let's say you use the thing for 15-20 hours a week. What's a good time=

> frame to replace all the tubes? In the case of the Ampeg, we're talking on=
ly
> preamp stage tubes.- Hide quoted text -
>
> - Show quoted text -

<<So, let's say you use the thing for 15-20 hours a week.>>

You should get years out of them.I have.

On May 15, 1:40 pm, "JoeSpareBedroom" <dishborea...@yahoo.com> wrote:
> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO. Do=

> tubes give any subtle warnings as they approach death, or does it tend to =
be
> sudden?

If you use the amp for gigging only it should last for years.
Pretty costly to replace 8 power tubes.
The biggest cause of burnout is heat.
Get a small clip on fan and use it every time you gig.
I just changed tubes in my Marshall.
Last time was over 5 years ago and I gig often.
Use a solid state amp for practice and rehearsals.

Pt

Pt wrote:
> On May 15, 1:40 pm, "JoeSpareBedroom" <dishborea...@yahoo.com> wrote:
>> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO. Do
>> tubes give any subtle warnings as they approach death, or does it tend to be
>> sudden?
>
> If you use the amp for gigging only it should last for years.
> Pretty costly to replace 8 power tubes.
> The biggest cause of burnout is heat.
> Get a small clip on fan and use it every time you gig.
> I just changed tubes in my Marshall.
> Last time was over 5 years ago and I gig often.
> Use a solid state amp for practice and rehearsals.
>
> Pt
fortunately both of the amps he's looking at are hybrids, having tube
pre's and SS post. About 70-100usd to change out 3 or 5 12ax7's and a
12au7 in case of the SVT3Pro.

Pt <peatea@yahoo.com> wrote:
> On May 15, 1:40 pm, "JoeSpareBedroom" <dishborea...@yahoo.com> wrote:
>> It's that time again. New amp, probably either an SVT-3PRO or
>> SVT-4PRO. Do tubes give any subtle warnings as they approach death,
>> or does it tend to be sudden?
>
> If you use the amp for gigging only it should last for years.
> Pretty costly to replace 8 power tubes.
> The biggest cause of burnout is heat.
> Get a small clip on fan and use it every time you gig.
> I just changed tubes in my Marshall.
> Last time was over 5 years ago and I gig often.
> Use a solid state amp for practice and rehearsals.
>
> Pt

The SVT-3 PRO doesn't have power tubes (it has an SS power section).
It's also got an internal fan (you can hear it whirl up when you first
turn it on).

On May 15, 11:40 am, "JoeSpareBedroom" <dishborea...@yahoo.com> wrote:
> It's that time again. New amp, probably either an SVT-3PRO or SVT-4PRO. Do=

> tubes give any subtle warnings as they approach death, or does it tend to =
be
> sudden?

Dont know...what do they have...I or 2 Pre amp tubes?....lol