Ordered at last

Finally was in the right place financially to press the button so I ordered my gm40d today and now wait delivery later this week.

I made the decision a while back and lucked across a second hand 112 cab in Andertons at a steal of a price.

I'll be putting the new amp directly up against my mesa Lss and some fairly high end boutique pedals. pretty stiff competition. Let the battle commence.

My plan is to take my celestion gold 12" out of the mesa lss and put it in the 112 cab. I'll put the original mesa black shadow in and sell her on. She's a great amp and all being well should sell quickly and fund the gm40d purchase fully. That is, IF the gm40 cuts the mustard.

I'm taken by the h&k switching possibilities and the possibility to integrate it with my es-8. The small size of the head for transport to rehearsals and gigs. Function wise and on the face of it this seems like my dream amp. I've also ordered a wmi-1 to get the iPad in on the fun.

I currently run a Princeton 68 as a stereo pair and fully intend to continue with that config.

Do you guys share presets anywhere?

Also, if I were to retube the amp fully. What should I be looking at and where would you recommend that I get them from? I'm in the U.K.

Look in the GM36 forum for a huge thread on valve swapping. There is a thread for sharing presets but as this is so dependent on other kit it has not even got off the ground. The settings I use for something would certainly be pretty different to what you would use given that our speakers, guitars and pedal choices would never be the same.

Thank you, I will have a look in the 36 forum. I will probably trial the gm40 as is to start with... if I decide to keep the amp then I will treat myself to some new tubes.

Not expecting great shakes from the 112 cab and the head alone but for my purposes playing largely at home or rehearsing in Studio where other cabs are available this might just work very well.

Getting ridiculously excited for NAD....

I tripped across Hennings youtube on the ES-8 and GM36 midi functions, that I think confirms what I am going to be doing with the es-8.

I will still keep my pedal board in the effects loop of course, but in time if the effects are as good as they seem online then I may just be able to do away with 75% of my pedals!

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So... looking for your advice guys, I got this GM40D delivered.... would you send it back?

On the underside of the top part of the cabinet there is a small metal plate which appears to be glued in place, in transport it has clearly detached itself.

I can initiate a return/ replacement with Thomann (the seller) but given that it took a week for it to arrive from Germany to the UK in the first place I really don't want to wait for a further two weeks (my return processed then their supply of a fresh one).

I have opened the case carefully, ensuring no voiding of the warranty just like everyone who has swapped tubes and pushed it back into place. My gut feel is to send it back because if this was down to drop damage then who knows what else is in store.

Thoughts, opinions?

Someone informed me that the loose part is a "heat shield". Think I'm going to arrange a replacement. God knows if indeed this was caused by drop damage what else is stored up.

Return arranged. I probably could have been talked out of it but thought it for the best.

Luckily it'll be away when I'm off to France skiing for a week so at least a new one will be on its way by the time I return.

I think that's one new thing in the GMD40, it isn't in my GM36 though that doesn't need it at all.  I'm not sure what they are shielding from the heat though, unless it is just the crowd pleasing "Deluxe" logo on the top! I wonder if it is perhaps just a response to customer criticism of the other amps in the range.

In the past a lot of people have bleated on about the case getting hot in the small H&Ks and have insisted it will cause reliability problems.  They really don't know their arse - - - errm, - - - haven't thought things through properly from an engineering perspective, (which is all that matters).    If you work on the figures for the amp you can easily see that the heat dissipated is nowhere as bad as people fear.  They are comparing it to the worst thing possible for heat, an insulated cloth covered wooden box with a couple of slits in!  (Well I suppose the worst would be without the slits).  That will always stay cool to the touch until it is actually on fire inside!!!  The H&K metal lid is actually designed to act as a heatsink quickly transferring the heat which rises straight to the top from the valves to the outside over its whole area.  As an exposed element it is controlled by a number of safety aspects concerning its maximum temperature so H&K have to be very sure it won't climb above a certain level, (or we'll sue you!).  The hand is not a good judge of absolute temperature, what feels burning hot to the touch is certainly not in electronic terms!  50degC is just about hot enough to hold while 60degC is only hot for brief contact.  Anything hotter and your hand tells you its burning.  The lower section containing all of the circuitry remains quite cool.

I've bleated on before about the lifespan of electronic components with respect to heat.  Semiconductors work without a problem at temperatures well above 100degC, the same as modern resistors.  Capacitors have a figure quoted for average lifespan, usually at 85degC though better ones can be at 105degC.  Even at a constant 85degC it is already in the 1000s of hours of use.  And their lifespan doubles for every 10degC they work below that temperature.  At 60degC, what your hand will tell you is very hot, they have over 4x that quoted average lifespan.  The idea of swapping out all electrolytic capacitors every few years is a total waste and the work of an idi.. - - - errrm, - - - very uninformed user who you should ignore!!!  As an aside, they don't "dry out" unless the case is damaged and they leak and that is obvious.  They use up the electrolyte inside repairing themselves if they are abused electrically in use.  Over voltage, over current, micro over heating, can all cause tiny punctures to the micro-thin insulating skin between the plates and the cap needs to self repair that.  If this goes on happening, over time the gel that provides the material for the repair gets used up and the cap then does need replaced.  That is no indication that all of the other caps in the amp are about to go faulty! The answer is that if the cap is correctly specd and the electrical conditions are controlled as they should be there won't be a problem of this sort.

It is pointed out that the power soak components are in there so it must get hot.  Well, the power soak would give off a maximum of 19W in 1W mode, (1/2 x 40W - 1W as one pair of valves is turned off), and in the real world that can be reduced as it is only a music signal with little low frequency content and is very transient meaning relatively low average power levels.  Even at the bottom in the top section with the valves it stays relatively cool too.  I do recall we did have someone with one of those remote temperature sensing guns check it out and reported very comfortable running temperatures.  It's a very effective way of keeping the amp cool and safe.

For my money I would go for a replacement too.  It isn't common for H&K to miss a fault of that sort in a new unit, that really sounds like transit damage.  And you're right, who knows what else could have been done.

:-) thanks bb for your (as ever) considered response.

I'll get her packaged up and away as soon as possible.

New amp delivered just in time for me coming back my skiing trip. Perfect timing :-) have to say that this second amplifier is much better in terms of the dreaded fizziness.

I haven't hooked up my pedals via the 4cm yet to this amp nor have I tried to hook in my fender Princeton reverb68 as my stereo set up but all is well with the replacement and so far sounding great.

Funny how a week away from guitar playing makes things feel alien.

Still no response from H&k via support or via their Facebook page re the wifi performance message I get from the wmi-1's ssid.

Interesting. I’ve just received and had to send back a GM40 with exactly the same problem Thomann we’re very good in dealing with this. Hopefully a new one will be here on Friday

Can someone post a decent pic of that panel correctly fixed in place inside the amp?  Without knowing where it is actually fixed in place I can't really imagine what it is there for. Is it aluminium or plain old steel?

Here’s a picture as delivered with it fallen off. Does this help? Glad to say new amp delivered this Monday and it’s awsome.

And with it in place. Sorry for picture quality, difficult with the reflections from the Perspex.

Thanks Madtone that is pretty clear. There doesn't seem to be much point to it to me. It looks like it's just a wide shallow channel with two narrow edges which would be in contact more or less at the front and back faces and would only prevent the top surface from getting heated directly from the valves beneath. The only thing I can think of is that the top surface must get discoloured or lose the 'Deluxe' logo through heating and this helps to keep it a little cooler. It's definitely making the overall cooling less efficient though by removing the top surface as a direct conduction path for heat to be drawn out. In reality there is probably not too much difference or they wouldn't do it. Definitely an oddity and not fitted on my TM36 or GM36.

Having seen comments on this forum, I was expecting the top to get hotter, after a couple of hours playing I can only say it gets warm at best. Seems like it’s there to stop the top getting really hot, but as you say this would make cooling less efficient. I presume the design guys at H&K feel there’s a need for it otherwise it wouldn’t be there.
I could have stuck the plate back on but I agree with the OP, you don’t know what other damage has been done. It was sitting rather precariously on the tubes so I don’t know what damage could have been done if I’d sparked it up. After all, I was expecting a brand spanking new shiny amp in perfect working order. Anyway Thomann sorted it out swiftly. It was bit frustrating having to wait another week, but it’s been well worth it.

Absolutely agree with you on the "repair a brand new amp myself?" principle. It shouldn't come to you with serious issues and it's almost always right to send it back. I have also found Thomann to be really hot on their after sales support. It's just a shame they are in Germany and there can be a longer delivery period to the UK (for me).

We have done a fair bit of calculation and testing in the past on the heat issue. Everyone seems to be worried about it or takes the opportunity to knock the amps based on the fact that the metal lid feels hot. The truth is that the H&K method is actually better for internal cooling than a wooden box with a couple of slots in it. It relies heavily on conduction as well as just convection. One member had an infra-red thermometer available and took internal readings as best he could. They showed nothing untoward at all. A number of us came up with forced ventilation methods too but I gave up on my little 12V fan stand as I found I really didn't need it at all.

I've posted in the past about how basic electronic components are affected by heat. Roughly speaking, if you can touch it without being injured they can bask in it quite comfortably. And that's even electrolytics which are highly misunderstood and unfairly maligned, there's no ticking bomb there!