Bad Tube???

Good morning. I purchased a grandmeister about a month ago. Last night at church service I heard some popping and crackling coming from speaker. When we were finished I looked at the back of the amp saw the TSC had one LED out. Any idea what could have happened? Is there a tube blown already? Thanks in advance

We had practice Sunday and powering up from cold there was crackling in speaker cabinet and TSC was same as the night before. I changed all my patches to 18W and the TSC lights as it should. Same for 1W 5W.

Last night i plugged in to play for a bit. Same popping and crackling big time. Now though at 36W the lights are all off, and when switching wattage, the lights operate as normal. I’ve sent an email to support but also wanted to post here. Thoughts??

My only thoughts are, please let us know the results...

haven't heard back from support that i emailed, i posted on the Facebook page, and also posted on one of the blogs on their website.... Really thought i'd get some kind of reply by now

If you are in the USA, you won't hear anything from the website. They do usually respond on FB within a day or less...
Did you try swapping the EL84s?

Yes i am in the USA. I have not swapped anything as its only a couple months old and i don't want to monkey with it much.

How would someone in the USA contact support then?

I too never had any luck with their tech support, but they are usually very responsive via FB and the blog... hang in there...

The LED indication has me puzzled, but I'll bet it's a bad tube. See what H&K has to say of course.

Do you have a spare set of tubes? If not, get some Tubes are weird, with unpredictable lifespans. They are a "wear item"... I keep a spare set handy, no different than having spare sets of strings for the geetars

I dont have any spare tubes...
I'd think that being this new a failed tube would be warranty replaced? I messaged again via facebook

I assume this is the correct page.
https://www.facebook.com/hughesandkettner

You posted to the correct FB page, I see your post.
I agree they should replace it. I thought I read in an older post where H&K did send tubes to a user...

(editorial section)
I (and some other musicians I know and have read about) have spare tubes in a gig bag whenever gigging with a tube amp.  I have a matched set of 4 EL84s and a 12AX7 in my rescue kit.  Because, tubes die.  They are mechanical and are a delicate piece of glass glued to a plastic base to seal a vacuum - all really bad ideas for reliability.  On a side note, that's why I used to always model and use a solid state power amp. My $.02.

Good info. I appreciate it. Do you replace the tubes with the same H&K tubes? I dont see anywhere to buy them. I see several other makes of tubes but how does one know which would be best?

You don't have to use OEM tubes. There are a million (OK, I'm exaggerating!) different brands/types of tubes out there and a million (OK I'm not exaggerating!) opinions on which tubes are 'best'. Some folks hear a night and day difference between different tubes and some folks don't hear any difference at all. It's all very, very, subjective.

I personally use JJ tubes. I've been using them in all my tube amps for many many years, and I've had very good experience with them. They are reliable (fact, not opinion) and they sound great (my opinion). I only ever had 1 bum set, but that was a set that I bought thru Musician's Friend instead of my usual vendor who does painstaking testing/matching. So, that was my bad.

Whenever I buy a tube amp, I buy JJ's and keep the stock OEM tubes aside as spares.

Give these guys a call: http://www.eurotubes.com and tell them you need three 12AX7 (also known as ECC83) and four EL84. They will take good care of you.
(sorry for the sales pitch - but I cant say enough good things about them!)

ps - changing the tubes is easy-peasy - we'll walk ya thru it

+1 on JJs. Good sound for a good price, very good reliability. I've used eurotubes (I have two t-shirts), thetubestore just had a sale...
Note the 4 EL84s should be "matched" - all stores will give you that option, sometimes you have to pay an extra buck or two, no biggie.

sweet! thanks guys. once i hear from H&K i'll let you know

Just made this video.

Here is the front start video
https://youtu.be/LmjIUQBptTs

looks like bad tubes to me

from the manual:
7.1 Automatic Status Indications
All LEDs light up and stay on:
All LEDs remain on for as long as the amp is in standby mode. When you
flip the "Standby" switch to "Play", they will extinguish after a few seconds.
If all of the LEDs remain illuminated, the most likely cause is a blown anode
fuse that needs to be replaced by a technician. The anode fuse can trip if
a tube is already defective when the amp is switched on, and TSC™ does
not have enough time to measure the idle current and to then shut the
faulty tube down.

None of the LEDs lights up:
The power tubes are operating normally.

One LED lights up continuously:
If only one LED lights up, then the tube assigned to this LED is not delivering
enough current and has been shut down. If the LED does not extinguish
after a few minutes, this tube must be replaced.
Two LEDs light up continuously
This tells you one of two things: Either the two corresponding tubes are
not delivering enough current and therefore have to be replaced (see the
instructions for one illuminated LED, section 7.1), or the power soak is
active. In the latter case, two tubes are switched off automatically, and the
two illuminated LEDs are indicating this (also see section 6.2).

One LED flashes, another lights up continuously:
The tube assigned to this flashing LED is generating too much current and
therefore has been shut down. This tube has to be replaced. In this type
of power amp, it takes a pair of tubes working together to produce the
best sound. So TSC™ also switches the defective tube’s counterpart off
(indicated by the continuously lighting up LED), so it doesn’t degrade the
other pair’s tone. There is no need to replace this tube, because there’s
nothing wrong with it.

Now this is where TSC™’s intelligence saves your gig: If a tube failure
like this occurs in a conventional amp, its fuse usually trips and you can’t
operate it until you replace the tube and fuse. Thanks to TSC™, you can
continue playing for as long as the LED remains illuminated. Anyway,
please note that shutting down one pair of tubes will halve the amp’s
output power from 36 to 18 watts. And don’t forget to replace the defective
tube after your show.

I agree with Normula. Those snap-crackle-pops distinctly sound like bad tubes.

Those TSC indications... (bear in mind I'm no tube expert)... When you flipped the amp out of standby, one of the LED's (#2) remained lit just for a moment. This indicates that something isn't quite right with that corresponding power-amp tube, but whatever it is, it's within tolerance. Next is the manual biasing test - I counted 12 concurrent flashes, then the two middle LEDs flashed twice, then the #2 LED flashes 4 times. This exceeds H&K's recommendation of having no more than a difference of 4 flashes, however it doesn't indicate a tube fault, it's only a bias matching matter. The amp will continue to function, albeit perhaps not with 'optimal tone'. It's not responsible for the noises.

So... as far as I can tell, the TSC is not indicating an absolute power-amp tube fault. However, my ears are hearing it! It's quite possible it's a pre-amp tube failure! As a matter of fact, in all the prior amps I've owned, when I have heard that snap-crackle-pop, it ended up being a bad pre-amp tube.

It's possible that all the tubes were perfectly fine when the amp was assembled and tested, but one (or more) have failed prematurely. It happens. Like we said, tubes are weird! If H&K spots you some new tubes, great. If not, I wouldn't waste a moment ordering a new full set.

Good luck and keep us posted!

Gotcha, with all the flashes how do i use the chart in the manual??

Taking it to guitar center today..since i didn't get their extended warranty i may be SOL.... we will see

That chart just tells you the bias rating. For example, when I perform the manual TSC test on my GM, I get 12 concurrent flashes, and then 2 of the LEDs flash once more. This means that 2 of my power-amp tubes are rated at "4" or 16.6v, and the other two are rated at "5" or 17.2v - well within H&K's recommendation.

In your case, your TSC is indicating that your power-amp tubes are well matched EXCEPT the #2 tube... it has a total of 18 flashes (6 more than your 12 concurrent flashes), which means it is rated at "10" or 20.2v - this is outside of H&K's recommendation (flashes should not exceed a difference of 4), but that's only in the context of "ideal tone", it doesn't cause any functional issues.

It is interesting that the #2 LED is also the one that stays lit for a moment when you flip the amp out of standby.

btw I think you're doing the right thing by seeing what GC will do for you.

if you listen to the long video, at 7:20-7:35 there is a sound which can only be described as the noise of the tractor beam being shut off by Obi Won Kenobi..... LMAO

https://www.youtube.com/watch?v=f62pW0J2JsA

Hi guys. Went to guitar center today. Best they could say is sounds like bad tube(s). Over 30 days cost of tubes is on me. They are like guitar strings. Wear and tear item....

I'm not too surprised. I hate to side with GC but I think that is a reasonable policy.

So.... time to go tube shopping Let us know if you want any help replacing them. Heck I'll walk you thru it over the phone if you want.

i spoke with the quality control engineer at the H&K distributor and he doesn't think its tubes but a leaky MOSFET?? What the heck is that thing??

I found TAD tubes here:
http://www.thetubestore.com/Tubes/TAD-Tube-Amp-Doctor but they are huge money.

This store https://www.amplifiedparts.com/products/vacuum_tubes?filters=Brand%3DTAD has for much less.

Has anyone bought from these places before?

I think it's a type of transistor but I don't know for sure. That stuff is out of my field of knowledge. I do know quite a bit about bobafett however but not mosfet.

Did the engineer watch your video clips and hear the noise?

LOL....I too know boba and jengo!

yes they watched both vids. My buddy has a set of EL84. we are gonna swap today and see if it fixes. if not i box it ship it and miss it for almost two weeks...
It'll be fixed under warrantty so thats good.

I hear a lot of great things about TAD tubes. i know they arent the manufacturer but H&K recomends them.