TubeMeister Deluxe 40

Hello,

I am new to this forum and will be replacing my Marshall 2 x TSL60's with my newly purchased TMD 40. I have noticed that there is not a forum for the 40 on this site and was wondering if there are any heads up before I put the new amp into a gig situation?

It's all about front of house and small venues now, my arena days are far and few between now! So pack it up in the SUV and let the FOH do the damage  

My set-up will consist of a GT112 cabinet positioned front of stage blowing back at me, Redbox on V/L to the FOH, Effects line will be TC Electronics Nova system. Front of amp input will be a Shure BLX14 Wireless, line 6 DL4, Dunlop GCB80 Vol Pedal, Peterson Stomp Classic Strobe Tuner, & Dunlop GCB95 Cry Baby. Guitars are a American Standard Strat, Les Paul Studio, Peavey Pre-Pat. Wolfgang, & Jap Charvel San Dimas.

Any comments will be welcome and do we see a TubeMeister Deluxe 40 forum soon?

So over the weekend I changed all my effects gear and midi commands over to the TMD40. The amp lasted 4 hours and smoked the TSC.

While setting up the amp for a performance set-up one of the EL84 took a dump. H&K is working on sending me a new amp head. Now I am having anxiety thoughts of the the quality of build & capabilities of this amp. $1K should last longer than 4 hours of performance time.

I have to say that, as an electronics engineer of far too many years standing, you won't get better build quality than H&K.  Their homework has been done, the designs have been proven, the calculations have been checked and double checked and the units are just plain built right!  There are no known regular areas of failure as far as I am aware.  We have had a number of people on here over the years who have seriously questioned some aspects of the H&K amps' design and build, (me included), but when you look into it properly you find that, as long as you like the H&K ethos and the house sound, you can't fault them.

Remember that fault was in a valve and the amp was damaged in response to that.  There is little that H&K can do to prevent a problem of that sort, it isn't any indicator of poor stock control, poor  design or build in the amp.  Now some will say that they could use more expensive "better quality" valves in the first place, (that would be their wording not mine, I don't subscribe to that way of thinking about components).  We queried them on this and the attitude was that almost all users will have their own favourite flavour of valve, (overstated though that idea is), and they will spend money replacing the stock valves pretty much immediately no matter what they are.  It's just what people want to do nowadays.  To use a more expensive valve at manufacture would just put the price up for everyone including those who are going to simply swap them out anyway.  And you never hear from the many many people who are perfectly happy with or even actually prefer the Chinese valves, they could well be the silent majority.  The cheaper Chinese "get you going" types are the cheapest option allowing you to put in your own inevitable preferences.  Or it could just be that H&K think the sound of those valves is closer to what they want their amps to sound like.

The TSC is the one area where the output stages have a direct serious impact.  It automates the bias setting, that's one area of concern out of the picture, and constantly monitors the state of the valves to tell you when they are on the way out, another detail taken out of our hands.  It is at least good that they took the fall and the rest of the amp was kept safe, (as in tube "safety" control).

I know it's a fag having this happen so early on in your honeymoon period but it actually happens with every piece of electronic equipment.  There is an inevitable hopefully very small percentage of units which go belly up due to component failures in the first stages of their life.  I'm fairly sure the replacement will whet your appetite again and things will be fine from here on in.

Bordonbert,

Thank you for the well penned reply.

I am an engineer as well, EEE working in the departments of Production, Quality Control, Design, and Technical Sales after years of playing as a touring rock musician. Today I play shows in a cover band to keep from ripping inept peoples heads off at my day job.  

Back to the TMD40,
The question I have is knowing all parts have a certain fallout percentage, is there less failures with this H&K series amp after people change the tubes to a major brand? If that is a correct statement then what brand of tubes have the greatest success and ratings with the H&K line?

I have always used JJ's in my Marshalls, Sovtek in my Mesa's, NOS RCA's in my Fender Twin Blackface for the power sections. We all should know that with preamp stage tubes it's a buy & try game that has a potential of being an expensive exercise.

There's a lot written about this in the GM36 Tube Swapping Thread which you should be able to find. I'll be up front here, personally I'm absolutely against the claims that are often made in the vein of "I rolled the tubes and got a new amp". It's Emperor's New Clothes stuff and we have other intelligent people here who have tested the idea with an open mind and come to the same conclusion as myself, valves make a small difference to tone at best. If it is genuinely there it should be easily demonstrable on the test bench and I've seen a fair bit of test bed data which refutes claims like this one and none which shows any differences! But the guitar "gurus" know best of course, and they continue to profit highly from those NOS types recently discovered in a monastery high on the Tibetan plateau. Show me the evidence and I will gladly change my stance.

I do hear what you are saying about the reliability of different manufacturers though. I haven't ever heard anyone use reliability as an argument for using a particular brand and have not ever come across any evidence that some are a lot less reliable than others. Except for this, (and I got flamed from the Marshall JVM forum for even suggesting it! ) In many amp designs there are one or more DC coupled cathode followers. These have a unique way of interacting with a preceding gain stage to produce a type of distortion which is right up there with the best of what we want. However that stage has a weakness which H&K have not addressed in their designs, much like the huge majority of designers of guitar gear. If it isn't an issue why do Bognor for one address it in a couple of their preamps? I actually put H&K onto this in their FB page and they started to use it in their marketing copy. There is a great website here for all things valve if you're interested in the genuine engineering side of guitar valve amps: The Valve Wizard That guy really knows his onions! I pointed the H&K boys to his description of the problem and the tonal benefits of it appeared very soon after in their advertising. But they still didn't apply the fix to that problem which is clearly described there!!!!

The problem is that if you turn on your amp from cold with the Standby off, that is with the amp active, the process can destroy a DC coupled cathode follower valve. Until the valve warms up and starts to conduct it violates the maximum grid/cathode voltage by a long way and the valve can literally go "POOF". This is a well documented effect with a cheap (maybe 10p or about $0.15 solution) but when I suggested that the Marshall had a potential problem because it didn't apply that solution, (a simple cheap resistor and diode across the grid and cathode), and they had left a potential problem in their amp(s), all Hell let loose. The very idea, Marshall amps have weaknesses in them that haven't been addressed! (I didn't even say anything about how Standbys kill your valves when you leave them with heaters glowing but no HT applied.) In truth most amp tech guys have probably come across this but just refuse to accept it should be a necessary implementation as all you have to do is to let your amp warm up with the Standby On. That's fine until someone kicks it off and you don't notice at switch on. I'm trained to design differently. If there is a potential problem I can see I look for a cure and put it in place before the problem causes problems!

Now the point of all of that rambling is that it is said that there are some valves which can withstand that bad treatment better than others and are more suitable for a DC Coupled Cathode Follower stage. And what do you know, they tend to be the cheap Chinese or Russian makes! So this valve manufacturer choice really could be done on the grounds that you have raised, reliability. Though again, I feel it is much of a muchness for most of it with the odd exception in cases as I have described.

Here is H&K's reply:

Hi,

The short answer to your question is “Yes, They’re reliable to use on stage.” I’ve used them before and there’s no reason to treat them with any more care than you would have given your Marshall. That being said, wooden chassis’ will absorb far more shock than a metal one, hence the reason for the inclusion of a bag for transport as a base accessory.

Insofar as tubes go, I haven’t found that generic Chinese tubes are any less reliable than boutique name brands. HOWEVER, I do prefer the tone of them. In my opinion, tubes like Ruby and EH are much warmer and natural sounding than the Chinese ones that come stock in the amp. As far as *your* specific issue goes, this issue is usually caused by a faulty Mosfet (or two). Although it’s not common, when this condition presents itself it’s almost always the issue.

I hope the information helps!

Herb
H&K Team

That's a very interesting response isn't it. That is one thing I will praise H&K for, at times they aren't afraid to say what they think and give out some useful info.

The metal chassis is a little less forgiving than a wooden one mechanically but there is another side to it. It is a much more effective heatsink and keeps the inner workings of the amp much cooler. That's not the upper compartment with the valve envelopes in but the lower one with the PCBs. The metal case conducts heat out as well as having a similar convection setup to a wooden enclosure. There was a question asked once as to the inner temperature when the top can feel so hot to the touch. We actually had someone use an infra red thermometer to measure it and it was easily within sensible limits as you would hope. Like our ears with sound, our sense of touch is really not a good instrument of objective measure. And of course the hot case was at the top not the bottom and electronic components are designed to work reliably at much higher temperatures than they encounter in any decent design of amp. Semiconductors are quoted to work up to about 150deg C and even the unfairly much maligned electrolytic cap has a lifespan of 10s of thousands of hours at temperatures of 60deg which is about as hot as your hand can stand (double the quoted lifespan for every 10deg below its stated temperature, usually 85deg or 105deg). Granted this is external to the component and local hotspot temperatures are higher but it is easily comparable to other average electronic equipment.

Interesting to hear him say he prefers the tone of Ruby and EH valves. I have a couple of EH 12AX7s I once used myself and I could hear a mild improvement over the stockers in the upper harshness which the H&K TM and GM seem to exhibit but it didn't amount to what I would describe as a difference in tone, though that could be said to be a matter of personal definition. And everything in the amp and supporting equipment was kept exactly the same at first, then only the Volume was changed to try to normalise the two valve types without changing tonal settings. If they acknowledge a difference, it is surprising that H&K don't release data, (frequency response and transient response curves would be a start perhaps), to show that difference. It would be the starting point of an intelligent process of choosing valve types which is full of myth and subjectivity and would shut up the naysayers like me once and for all.

Our valves are in general pretty wideband devices. The class of valve we use in guitar work are the radio receivers which generally have to be wideband. Even if some (our venerable 12AX7) are less wideband than others, at severely restricted audio frequencies for guitar (maybe 8kHz with the wind behind us), poor bandwidth speakers as ours are, in stages with feedback as most are there could be very little effect on overall frequency response as long as Miller capacitance is correctly designed for. You don't leave a circuit to get its tone from the characteristics of the particular device you plug into it! If you do then you get a different sound at every valve change even in valves of the same type and make otherwise you resort to selecting acceptable devices with massively higher costs. My own gut feeling is that the thing which could perhaps differentiate between makes could be clipping characteristics and that would be very difficult to normalise to get truly objective comparative results. Someday someone will try it and release what they find.

The MOSFETs he mentions are the active element in the cathode circuit of each output valve so any fault in a valve leading to a high enough current surge or possibly voltage spike will put them under pressure. They are 600V 10A devices and they are fully zener protected so they will take quite a bit of abuse in normal use. We have seen a couple of problems here over the years where they have taken the fall but nothing beyond what you might expect.

Anyway, enough blether from me, back to your day job decapitating the great unwashed!