NOS tubes-update

[bscfo1]

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[Mick]

Sorry to hear about your bum tubes but I've received nothing but good solid no BS advice and tubes in 3 different dealings with KCA. How about some more details like what kind of amp? What kind of tubes? And what did whoever sold them to you tell you about the tubes?

 

[tejastubes]

Sorry to hear about your experience with KCA. My opinion, as a tube dealer, is that NOS tubes make a huge difference in the quality of tone, and they way the guitar sounds when running through the amp, as well as the quality of distortion. Most, reputable tube dealers will noise test their pre-amp tubes and match their power tubes for current draw PRIOR to shipment.

 

[MikeKCA]

All tubes are tested prior to shipment. Testing does not predict the future or guarantee that every tube will work in every amp. The warranty covers the less than 1% of tubes that customers have problems with.

 

[stokes]

Just how does a pre-amp tube affect the bias of a power tube and cause it to "glow red"?

 

[tejastubes]

To the best of my knowledge pre-amp tubes don't cause the power tubes to glow red, it has to do with the stability of the power tube, how much current it is drawing and where the bias of the amp is set. I may be wrong, but this has been our expereince. When buying NOS power tubes the amplifier should always be re-biased or serviced by a tech to make sure your tubes do not "red plate" as described. In most cases this should only cost approx $20-35 from a reputable tech.

 

[stokes]

Could not agree with you more,tejas.

 

[Guitarzan]

Just how does a pre-amp tube affect the bias of a power tube and cause it to "glow red"?

Glowing red power tubes is a sign of a bias issue. With a mesa you'll have to find the right rating of tube to suit your purposes.

 

[disassembled]

Glowing red power could be a bias issue but more than likely it is a faulty tube. Right before most power tubes croak they turn bright red( not to mention, sound awesome!). After that usually the screen resistor blows, the B+ fuse blows, or both. Testing tubes on a silly tube tester does not indicate tone, noise, pops, microphonics, etc. A truly dedicated NOS dealer should test each tube in a real world application (ie high gain guitar amp) before they shipped out to avoid problems like this. If they do this they can at least say it was fine before it left shop and can start narrowing it down to shipping, operator headspace, equipment failure, etc.


Preamp tubes have nothing to do with the electrical power that goes to the power tubes.

If you are scared of old tubes contact Bob at Eurotubes.com or Doug at dougstubes.com. They will be able to hook you up with current manufactured tubes that are warranted.


Or you can just go solid state.

 

[tejastubes]

Yes they are a fixed bias amp, so again I suggest calling Mesa on this one. Perhaps one of the NOS tubes you installed was the wrong tube type. I have always found them extremely helpful as well as knowledgable. I love my mark II C+, and they did a knock up job on it. There tubes are eh,,,nothing like NOS, but the amps are great!

 

[bscfo1]

What about a phase inverter tube? Will that affect the power section in any way?

 

[Guitarzan]

What about a phase inverter tube? Will that affect the power section in any way?

Yes...an unbalanced PI will not allow all of your signal from the preamp to be optimally coupled to the power tubes . Hence, a lower signal and output.

 

[tejastubes]

1st, let me say that I agree and disagree with the above comment about the testing of tubes in the "real world". Just because you use a "high gain" amp does not mean this is "the real world". If I noise test a pre-amp tube in a Fender black face and you use a Boogie Stilleto, then this means the pre-amp tube was tested in a lower gain circuit, but this does not mean a pre-amp tube has to be tested in a high gain circuit for the noise test to be "real world". The Hickok 118B we use screens tubes for gas, shorts, leaks, and transconductance, and then we test all pre-amp tubes in a REAL audio circuit, not some gizmo like the VTV tube characterizer (which we feel is not worth the money and almost anybody would do better spending the same $$$ on an actual guitar amp, but this is another thread). But to say that the cicuit has to be "high gain" is absurd.

2nd, the PI should be balanced and if you put the wrong tube type in that slot when it actually calls for another type of tube perhaps this is part of your problem.

 

[Guitarzan]

1st, let me say that I agree and disagree with the above comment about the testing of tubes in the "real world". Just because you use a "high gain" amp does not mean this is "the real world". If I noise test a pre-amp tube in a Fender black face and you use a Boogie Stilleto, then this means the pre-amp tube was tested in a lower gain circuit, but this does not mean a pre-amp tube has to be tested in a high gain circuit for the noise test to be "real world". The Hickok 118B we use screens tubes for gas, shorts, leaks, and transconductance, and then we test all pre-amp tubes in a REAL audio circuit, not some gizmo like the VTV tube characterizer (which we feel is not worth the money and almost anybody would do better spending the same $$$ on an actual guitar amp, but this is another thread). But to say that the cicuit has to be "high gain" is absurd.

2nd, the PI should be balanced and if you put the wrong tube type in that slot when it actually calls for another type of tube perhaps this is part of your problem.

Which comment are you reffering to?

 

[disassembled]

1st, let me say that I agree and disagree with the above comment about the testing of tubes in the "real world". Just because you use a "high gain" amp does not mean this is "the real world". If I noise test a pre-amp tube in a Fender black face and you use a Boogie Stilleto, then this means the pre-amp tube was tested in a lower gain circuit, but this does not mean a pre-amp tube has to be tested in a high gain circuit for the noise test to be "real world". The Hickok 118B we use screens tubes for gas, shorts, leaks, and transconductance, and then we test all pre-amp tubes in a REAL audio circuit, not some gizmo like the VTV tube characterizer (which we feel is not worth the money and almost anybody would do better spending the same $$$ on an actual guitar amp, but this is another thread). But to say that the cicuit has to be "high gain" is absurd.

2nd, the PI should be balanced and if you put the wrong tube type in that slot when it actually calls for another type of tube perhaps this is part of your problem.

Which comment are you reffering to?

He is referring to my comment. Well sir, I apologize for being so one sided on the testing of a high gain amp(it was just 1 suggestion that I figured would get my point across). I was looking for relevancy as this is a site for amps that were mostly designed to be totally high gain, have a high gain channel, or played at extremely loud volumes(with some sort of high gainness in there). Don't confuse my statement of high gain with 100% saturation of the preamp and power amp with 5 stages of cascading gain.

I still don't care what rating you get on a tube tester because how can I be sure the rating is universal as the uninformed consumer? All I know is that when I plug this tested tube into my amp, it squeals, I want my money back; period. I don't care if it the most linear tube for HiFi amps and sounds great in super low gain guitar amps. If it works with low microphonics in a high gain amp(A good example is Peavey 5150, Triple XXX, or Mesa Dual Rec to name a few popular ones) at loud volumes then it should be work in a fender. Right? A fender black face wouldn't need tubes with extremely low microphonics like a cascading gain amp. Right? So why bring up grapes when we are talking peaches?

To the original poster:

Some people prefer unmatched phase inverters but most prefer balanced phase inverters. Most good tube suppliers can provide balanced tubes for these duties (such as eurotubes.com and dougstubes.com). This is another part of the Tone Pie that can be customized.

 

[Guitarzan]

Gotcha. It makes sense now.

 

[stokes]

Just how does a pre-amp tube affect the bias of a power tube and cause it to "glow red"?

Glowing red power tubes is a sign of a bias issue. With a mesa you'll have to find the right rating of tube to suit your purposes.

That is why I always recomend doing an adjustable bias mod,less than $2 for a cermet pot and you can use any power tube you want.About my original question,the original post said the new pre-amp tubes caused his power tubes to red plate,I was being sarcastic,sorry.

 

[MikeKCA]

Just how does a pre-amp tube affect the bias of a power tube and cause it to "glow red"?

Glowing red power tubes is a sign of a bias issue. With a mesa you'll have to find the right rating of tube to suit your purposes.

That is why I always recomend doing an adjustable bias mod,less than $2 for a cermet pot and you can use any power tube you want.About my original question,the original post said the new pre-amp tubes caused his power tubes to red plate,I was being sarcastic,sorry.

Sarcastic with good reason.

 

[tejastubes]

Communicating the type of amp in which the tubes will be used is the customers responsibility. If you use a hi gain amp then we need to know so we can noise test the tubes accordingly. Tube testers are very useful as the reveal problems with tubes and relative strength but the ultimate test is the actual circuit. Guitar players should realize that a tube dealer is NOT responsible for how a tube will perform in YOUR particular circuit. And every time a customer has a had a problem of this type, we have provided a replacement. So if you contact KCA, I assume he should make good on it. If he doesn't, then email me and we will find you what you need. We have over 4000-5000 NOS audio tubes in stock so finding some that will work in a "high gain" situation should not be a problem.

 

[bscfo1]

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