# tube amp long warm up time ....



## GTmaker (Apr 24, 2006)

Is it an indication of something wrong when a tube amp takes 15 minutes or so to sound as it should?

Before that long warm up time, there is hiss ( way more then usual)..
The amp sounds thinner ( needs more on the bass know)...
In general, the amp does not have the warmth it should have...

After a long warm up ( minimum of 15 minutes maybe a bit longer ) which seems like a lifetime....the amp sounds great as it should...

whats the prognoses doctor ?

G.


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## bolero (Oct 11, 2006)

what amp?

if it's old maybe it needs some new capacitors

also is it tube rectified or solid state? I'm not sure if a bad rectifier tube would cause that, but maybe


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## knight_yyz (Mar 14, 2015)

Maybe the bias voltage is off? I have no idea what happens to an amp when the tubes are shot.


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## WCGill (Mar 27, 2009)

This is probably in the range of normal. I've built a few AC30 types and one guy in particular says it sounds much better when it's good and hot (30 minutes or more) versus just after turn-on. He's a great player with good ears.


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## StevieMac (Mar 4, 2006)

In my experience, some of my tube amps have sounded "better" after a 1/2 hr of playing, especially in performance situations. With that said, I would attribute that perception to having tweaked the amp's settings during that time to sit right where I want it in the band mix. The same principle of "tweaking the knobs to perfection" could apply to solo situations. I wouldn't describe the sound of my amp's as "thin" or "lacking warmth" prior to final set up though...they just didn't sound "quite as good". This leaves me wondering about the operation of the OP's amp then....


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## dtsaudio (Apr 15, 2009)

We really need more details. Is this a kit, what amp is it, has it been modified etc, etc.
As an aside, I had a customer complaining about a similar issue with an amp he built. He had 6.3V for the filaments, but wired the input tubes for 12.6V.The thing took forever to warm up and sounded quite bad. Changing the wiring cured the problem. He was quite embarrassed.


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## TA462 (Oct 30, 2012)

I have 4 tube amps, a Orange OR15, Orange Dark Terror, H&K Tubemeister 18 and a Traynor YBA 1 Mod 1 and they all sound better after 15 to 20 minutes of playing. I think its normal. I usually turn them on and let them warm up for 5 minutes before I start playing.


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## loudtubeamps (Feb 2, 2012)

The warm up period and associated variations in tonal quality you are describing sound pretty extreme.
Yup..most tube amps start to open up/ fatten up after they are hit with full b+ and start drawing current under amplification after a few minutes, to be sure. For this reason,I always leave my amp on, (not standby) between sets, etc. till' I'm finished the gig.
Someone mentioned bias?? If we are dealing with a fixed bias circuit in your amp......
A Suggestion? I would measure the bias voltage on pin 5 of your output tubes (assuming they are 6V6 6L6 or 6CA7's) at start up and then measure again after your 15 minute "sounding better now" warm up period. Is there a - D.C. voltage difference?
I have seen bias feed resistors fail/drift and sometimes come back into range with time and exposure to ambient heat.They usually drift low causing too much current draw on the associated tube but.....ya' never know. Just a thought....


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## bolero (Oct 11, 2006)

GTmaker, did you ever get this figured out?

I am curious about it, could be some useful info for everyone

thx


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## GTmaker (Apr 24, 2006)

bolero said:


> GTmaker, did you ever get this figured out?
> I am curious about it, could be some useful info for everyone
> thx


because the amp sounds so good after a nice warm up period ( Im thinking 15 minutes ),
I think its the effect of having a fan inside the chassey that goes on as soon as the amp is powered up.
Seems to me that the fan delays the tubes to heat up to proper running temperatures on start up.
that's my theory and I'm sticking to it....

G.


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## bolero (Oct 11, 2006)

what kind of amp is it???


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## parkhead (Aug 14, 2009)

loudtubeamps said:


> The warm up period and associated variations in tonal quality you are describing sound pretty extreme.
> Yup..most tube amps start to open up/ fatten up after they are hit with full b+ and start drawing current under amplification after a few minutes, to be sure. For this reason,I always leave my amp on, (not standby) between sets, etc. till' I'm finished the gig.
> Someone mentioned bias?? If we are dealing with a fixed bias circuit in your amp......
> A Suggestion? I would measure the bias voltage on pin 5 of your output tubes (assuming they are 6V6 6L6 or 6CA7's) at start up and then measure again after your 15 minute "sounding better now" warm up period. Is there a - D.C. voltage difference?
> I have seen bias feed resistors fail/drift and sometimes come back into range with time and exposure to ambient heat.They usually drift low causing too much current draw on the associated tube but.....ya' never know. Just a thought....


15 minutes is too long. 

some things change as an amp heats, and it depends on the amp. I had a Fender concert that sounded better after about 30 minutes, but it never sounded GREAT. I had a 73 Deluxe reverb that would sound bad if you left it on between sets, the power transformer would heat up and start to lose efficiency so after a long night it would get dirty and smear notes a lot more. 

I got rid of the deluxe because of its inconsistency (I was always pushing it too hard) 

Unless temps are sub zero your amp should be up in about 1 minute otherwise you have a problem, or a part that is changing spec as it heats up and you like the sound of the heated part better. 

I have also seen 
the room change sound as humidity and temperatures went up (air gets heavier and you lose treble & clarity) 
frequent changes in sound due to poor power in clubs 

p


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## Rski (Dec 28, 2013)

This thread on this matter of does a tube amp sound better or sweeter is interesting. On one hand it may be just placebo. One thing I do know is I never cared for a stand by switch in any of my amp builds. The 6v6 or a el34 tube warms up with no hum to tame down, however, other builds with 6l6 or kt88 tubes do sort of hum when the conduction reaches setting dialed of the power tubes, after a while that humm diminishes to very soft hum that normal for most guitar valve amp.

The interesting thing about this extended warm wonderment, is, I mostly play fairly soft levels when inspired to noodle around with my guitars. The reason for this, I raised a family, very seldom did I have the opportunity to wail at free will, I respected my wife and kids. I lived out of town during one part of my career in a recording enthusiast home ... had more opportunities to wail there. I lived in a town house for several years .. and now my own house with a tenant down under, better then the town house.

When any push pull configuration of tube power amp is played at low levels, or even solid state clas AB amp such as my 70's pride analog possessions, low level distortion can become a niggle to discriminating listeners, so maybe the sweetness with tubes amps do really need some warming to whisper that sound that inspires gratitude that your tone is dancing at your fingertips.


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