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How hot should my DT50 get?

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I've had my DT50-112 less than 2 days.  I'm playing at very low volume, low power setting, class ab, voicing III.  I notice a smell, which I think is paint or varnish (or tolex?) at a temperature close to melting or burning, but it could be an electronic component too (I'm not an expert in odors).  

 

The guy I bought the amp from claimed to have only used it for 2 hours, so at first I thought it was maybe a normal break-in kind of smell.  But when I touched the metal amplifier housing in the rear after playing a couple of hours, it was very hot.  Not hot like a muffler pipe, but hot enough that if you needed to hold your hand to it for whatever arbitrary reason, you wouldn't do so for more than 2 seconds without leather welding gloves.

 

Upon removal, the power tubes look mint to me.  The screws did not appear to have been loosened previously, however, one of the transformers has a couple screwdriver dings in it--could be a factory thing, but I think that seldom occurs at the factory (even a Chinese factory).

 

So is this kind of heat normal?  (If so, I'll just get a fan.)  My previous tube experience has been with a vintage Dual Showman, and I never was concerned with heat buildup.  But with this amp, with basically only 2 tubes, maybe it runs much hotter in order to get that tube vibe?

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I've had my DT50-112 less than 2 days.  I'm playing at very low volume, low power setting, class ab, voicing III.  I notice a smell, which I think is paint or varnish (or tolex?) at a temperature close to melting or burning, but it could be an electronic component too (I'm not an expert in odors).

 

I would get that checked out if it's too hot. Like you said, how hot should it get in there? I know the tubes radiate quite a bit of heat as do the transformers. Ambient temp is an important factor. If your environment is cold it shouldn't get very hot if it warm I would expect it to get hot. Next time I fire up my DT50 I'll check with IR thermometer and record the ambient temp too.

 

I suppose the more the volumes and drives are maxed the hotter it gets but I can't substantiate that.

 

You could call Line 6 and ask them or do a support ticket. If anyone knows they will be the ones.

 

When I first fired up my DT it had a faint electrical/paint smell that dissipated.

Edited by Brazzy

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That would be awesome, Brazzy!  I'm going to try to wedge an oven thermometer to it somehow, though I am not sure it'll work.  I did fire up the old Dual Showman Reverb, and it did get hot, but not as hot.  Plus it has maybe 20 tubes in it as opposed to the DT50's four.

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Who the hell buys an amp and sells it after two hours? Sounds very weird to me.

 

My dt12 tubes are too hot to touch, and smell warm if I put my face to the back of the amp, but the rest of it is cool to the touch. Sometimes, if the amp has been idle there can be a little dust on the tubes which burns and smells a little when it warms up, but your description sounds a lot worse that these..

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Who the hell buys an amp and sells it after two hours? Sounds very weird to me.

 

Good point "I". It a bit suspicious but ya just never know. People do strange things.

 

Personally, when I buy something I know what I'm buying and that I'm going to keep it. Unless it's a complete lemmon. I've been known to work through even the worse of problems with products only to be completely happy with them years later. I know and learn more that way. It's gotta be pretty bad for me to get upset, which at this point in life is pretty much non existent, lol.

 

If I remember correctly only the tubes in my DT were hot which is normal for this amp, I think. I know tubes amps can vary quite a bit.

Edited by Brazzy

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Thanks, "I" and "B!"

 

I'd give the guy a 50% chance of exaggerating a bit versus out and out lying.  He'd owned it nearly 8 months and didn't use it much (supposedly).  Some musicians buy on impulse.  He had a lot of gear he didn't need.  He described buying and selling gear as "kind of a hobby of mine," but he wasn't bragging, it was kind of like self-criticism the way it came off.

 

Anyway, on both this amp and my Fender, the metal chassis that houses the non-tubular circuitry gets hot.  To some degree this is just physics, because tubes heat up, heat rises, and the chassis sits above the tubes in these particular amps.  (I don't understand why any amp builder would invert the chassis like this, but it's fairly common.)   The DT gets hotter than the Fender, like maybe 20-30% warmer, even though it has less tubes by far.  The question is how hot is normal?  If it's hotter than normal, then I need to get it looked at.

 

If the metal box that covers the electronics (the chassis) on your DTs does not get hot after 30+ minutes of playing the way I described in my OP, then I need to explore whether I actually do have 4 months remaining on the transferrable warranty or not.

 

Thanks!

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Well, folks, I don't know what was happening before, but it seems fixed now--and WOW!  This amp is amazing!!!  It doesn't meet, it actually surpasses my high expectations for tone.  Best amp I've ever played through, that's for sure.  And even at low volume it sounds so awesome.  Now that I've shut down for the day, I'm still taken aback.

 

All I did was re-seat the tubes and leave the cage off the power tubes and the panel off the back of the cabinet.  Not sure how much difference either made, if any, but now it only gets warm in back.  I could hold my hand on the chassis all day, and actually kinda prefer that, climate being what it is this time of year.

 

I did faintly smell the cooking paint smell at first, but I think it's gone for good now.  

 

I'll be monitoring the heat back there regularly as well as investing in a small electric fan to keep my electronics cool and long-lived.  

 

If it acts up again, I'll revive this post, but for now, good bye folks--and thanks!

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That would be awesome, Brazzy!  I'm going to try to wedge an oven thermometer to it somehow, though I am not sure it'll work.  I did fire up the old Dual Showman Reverb, and it did get hot, but not as hot.  Plus it has maybe 20 tubes in it as opposed to the DT50's four.

 

I measured the temp of my DT50 Head by just holding a Cat No 22-171 Radio Shack Waterproof Pocket IR Thermometer as close to the screen in three spots. In the middle were the tubes are measured approx. 170 degrees F, to the left and right were around 90 degrees F. I would estimate the glass is around 200 degrees. Remember, this is an estimate and the testing was done indoors in a low humidity room at approx 78 degrees F.

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That IS awesome, Brazzy! By "glass," do you mean the shiny faceplate the knobs are on? (Is that glass?)

 

Wow, sounds like your amp gets as hot as mine did the other day. I was able to wedge the oven thermometer so that the back side of it rests up against the metal chassis, but the needle didn't even budge from its 140 deg min. But then my amp didn't run hot yesterday either. And really, if I'm in low power mode with the master at 4, things should stay pretty cool in a setup like this, I'd think.

 

I take it you're gigging, you're not using LPM, and you're running the volume past five (i.e. 12:00), correct? You're still running hotter than I'd be comfortable with. I used to play with a guitarist who had an awesome 70's silver face Bandmaster Reverb head and the larger matching cab, and he had a tech install a fan so that whenever he powered it up the fan ran. "Gotta keep those tubes cool," he said. With my DT50-112, all I have to do is run to Walmart and slap in one of their little fans, but for the DT50 head you might consider what this guy did.

 

It's good to know that my amp isn't alone in accumulating so much heat!! Heat is the enemy, always, but if it's designed to withstand a certain amount, that's reassuring. Thanks a ton for doing this!!!

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That IS awesome, Brazzy! By "glass," do you mean the shiny faceplate the knobs are on? (Is that glass?)

 

Sorry I referring to the glass power tubes. The face plate is made of plexiglass, I think that just get a little warm. Usually I run the master at lower than 12 oclock. I must admit, at 12 oclock It sounds great even in small areas at lower preamp volumes with the gain pushed up. When this amp is opened up with that just that one DT25 Cab it's awesome tones just spewing from that cone.

 

Thanks for the tip. I think I'll set a little fan back there to blow the heat out of the tube oven, lol. We all should know excessive heat is the enemy.

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170°F at the tubes doesn't concern me.  Brazzy, can you get a reading from the back side of the metal chassis roughly in the midpoint (to compare with my findings), or would you have to take it apart?  I wouldn't ask for that!

 

Thanks for the post in the other thread as well as this one!  So now my concern about my amp's health is escalating again.  I was experimenting with the L6 Link and the patches that come with the firmware for that and I smelled the smell again.  Not as strong as before.  Heat not as hot as before either.  But reduced symptoms are to be expected because I have the back off and the guard over the power tubes off, so air flow is better than it was and the heat doesn't have the same opportunity to build up,

 

I'll see if I can borrow an IR thermometer myself, as well as check to see if Walmart has its selection of fans on the shelf this time of year.

 

So you're running the DT50 head into a DT25 cab?  I've been thinking of picking up one of those so I have 2 cones, but standing in the sweet spot of just the one is so totally amazing that I dunno...

 

THANKS!

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170°F at the tubes doesn't concern me.  Brazzy, can you get a reading from the back side of the metal chassis roughly in the midpoint (to compare with my findings), or would you have to take it apart?  I wouldn't ask for that!

 

I'll check the chassis later but I remember seeing 85 degrees when I aimed toward the metal chassis under the tube area. Nowhere on the chassis was hot to the touch so it must be under body temp 90's. My body temp runs on the hot side so it must be under 96 degrees, lol.

 

I hooked up a 16ohm JCA12S+ and the DT25 cab in, I think it's called "in Parallel" to the 4 ohm output on the DT and it was a good sound but I just don't need to do that 'cause the one speaker is so good.

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I finally got smart enough and courageous enough (my amp's in an awkward-to-reach location) to touch the transformers.  The one furthest from the tubes was actually cool to the touch.  The one on the other side was a bit warm, due to proximity to the tubes, I assume,  So it can't be coming from the transformers.

 

Even in low power mode, even with the covers off, that chassis still heats up, unlike yours, Brazzy.

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Thanks for the tip. I think I'll set a little fan back there to blow the heat out of the tube oven, lol. We all should know excessive heat is the enemy.

 

I've been googling, and among gear heads there's somewhat of a debate about cooling fans.  One guy says they cause the tubes to work harder in order to maintain their operating temp, and claims that amps with fans have more tube failure, and further that the tubes closest to the fans failed more than the ones farther away.  Another guy talks about the heat causing his circuit board to warp.

 

Brazzy, if your head has the chassis at the bottom, below the tubes like a Marshall, you probably don't want a fan.  In my case, I can't ignore the threat to the electronics that are sitting directly above the tubes (even if I could ignore the heat issue with tubes all by themselves).

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Brazzy, if your head has the chassis at the bottom, below the tubes like a Marshall, you probably don't want a fan.  In my case, I can't ignore the threat to the electronics that are sitting directly above the tubes (even if I could ignore the heat issue with tubes all by themselves).

 

Hey thanks, I see your point and I know you have the combo and it's different in that it's upside down compared to the head. Since I don't have the kind of experience that many guitarists have I'll take heed in the fan thing. Since this thing didn't come with a fan I'm not going to concern myself with it.

 

I had an Uncle that was a Chief in communications on an aircraft carrier and he had experience with tubed radio equipment. He said to me once that they had many radios which would run and they never shut them down. He also said that the tubes in the radios which were never turned off lasted the longest indicating it was better to just leave them burn. I would imagine they used tubes made in the USA like RCA, Sylvania, GE, Mullard, etc., though I don't know for sure.

 

 

Well this is definitely too hot... lol...

 

That gif is priceless radatats!! Now I just installed a Kiddie Fire Extinguisher on the side of my Amp Head!! LOL

Edited by Brazzy
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I measured the temp of my DT50 Head by just holding a Cat No 22-171 Radio Shack Waterproof Pocket IR Thermometer as close to the screen in three spots. In the middle were the tubes are measured approx. 170 degrees F, to the left and right were around 90 degrees F. I would estimate the glass is around 200 degrees. Remember, this is an estimate and the testing was done indoors in a low humidity room at approx 78 degrees F.

Brazzy, you definitely deserve some recognition for your efforts here!  Thanks!!!

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Brazzy, you definitely deserve some recognition for your efforts here!  Thanks!!!

 

Thanks Man!

 

I dug up a little more info, check this out. The Thread Link

 

Carol-AnnAmps user_offline.gif

All tubes have a maximum 'Allowable spot temperature' rating, which is the maximum hotest temperature on any part of the glass envelope during use.

 

For most EL34's it is approx 480degF, although for most of the time they won't get hot as that.

 

However, I have blistered the skin on the back of my hand from a tube burn. They are nasty and hurt like hell, like a bad soldering iron burn.

 

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