GM40: Some general concerns before buying

Hi guys! Just found this community!
Hope everyone is enjoying their GM40.

I am moving from heavy amps due to a back issue and the GM40 seems to be perfect. I currently have a Marshall JVM410 half stack and a Peavey 5150 Half stack. I now want a light weight head and 2 "1x12" cabinets so they are easy to carry.
I will in Asia so buying gear and shipping is a very expensive option.
GM40 seems to cover all my tone needs; i have a Helix for the rest.

My main concern is reliability as here and elsewhere i have repeatedly read about issues, dying amps, no sound, midi channels and effects jumping etc.
I am sure it is a very small minority who face issues with such an advanced amp merging analog and digital technology.

Are their any mods which can upgrade components in the analog section to make the amp more reliable ?
Kruse Kontrol amps also offers mods for the GM40 and his circuit mods do sound really good.

Lastly, how do you guys feel about 2 vertically stacked 1x12's with the GM40. I am sure i will miss my 4x12 cabs, but i simply cannot deal with the weight anymore.
If the GM40 is reliable and solid then it solves all my problems indeed!

I would really appreciate your thoughts and opinions
Thanks
Nyne

All I can say is my own GM40 has worked flawlessly. Like you say it's probably a tiny minority that develop problems, and H&K seems to have good customer support, so I wouldn't worry about it.

Stacking the cabs won't sound quite the same as a real 2x12 or 4x12, but it will still sound good. Maybe you lose a little bit of low end? But so what. You won't notice any difference when you're actually playing with bass and drums.

What do you mean a "real" cabinet Johnny?     I'll have you know I use 2x 1x12" cabs in preference to my 60s Marshall 4x12, and they are cheap and cheerful ones at that.

No, joking aside I know what you mean. There is a feeling of security about a good solid beefy 4x12 but there is no reason why you shouldn't get as good a sound out of say a pair of 1x12s.  I use cheap Harley Benton ones which I bought new for about the same price as the V30s which were in them.  They didn't suit the GM36 until I replaced them with G12M Greenbacks but they are awesome with my Marshall JVM205H in their original state.

The important thing is to try them before settling on one choice.  Speaker selection really is the major factor in tone after the amp model itself.  It blows valve choice out of the window in terms of its importance.

Very happy with mine. The bug where the amp switches its power soak to 0W the first time I switch channels via MIDI is annoying, but I've learned to take care of that right after I turn on the amp. Very reliable and killer sound...got big compliments playing an LP through it using the crunch/lead channels at an open mic last week.

You asked about reliability Nyne.  I can tell yout that the H&K amps are extremely reliable despite the uninformed scuttlebutt out there in Guruland.  There are a couple of factors to consider here.

I can tell you, as an avid Marshall user and lover, Marshalls are much more likely to suffer problems than an H&K.  Their designs are considerably more "old school" and the technology which Marshall is kept tied into by the ultra-conservative (Luddite!) section of its market base due to totally uninformed ideas about its performance is often plain out of date.  Marshall are trying but always meet resistance on behalf of some of their customers, (just like Gibson!)  H&K openly pride themselves on using up to date methods correctly applied from the off.  In my time here as a H&K user, (TM36 and GM36), I have had extreme arguments about the "poor" quality of transformers and wound components used.  However, I cannot recall ever coming across anyone needing to change out a transformer.  I have fought against proponents of "hand-wired" tech in favour of the compact PCB construction used in the amps.  It does have the downside that when something goes wrong it is more complex to repair the problem and can eventually need a full board replacement but it is proven much more reliable after a short burn in period when implemented as well as H&K does it.  There have been questions about overheating as the enclosures are small and packed.  The figures don't lie.  Calculations show how little heat energy there can be in the lower compartment and we even did some pretty extensive work on the GM36 in terms of actual internal temperature measurements.  Thanks to the intelligent layout and the heatsinking metal enclosure, the H&K compact amps are at least as cool as insulating wooden cased classic amps.

As far as I know, we are the only online resource for H&K gear.  We have a great relationship with H&K direct who have advised us a number of times on technical questions.  It is likely that most online searches for independent help with H&K gear would find us.  You can see for yourself how few real problems there are reported here.  Compare that with the problems reported for other amp makes in the many forums which exist for them.  H&K's reliability record is up there with the best of them.

At the end of the day we all have a choice.  Those who prefer the hand-wired old technology approach for whatever reason have many, many amps out there built in that way to choose between.  They are incredibly expensive for what they are.  (Trust me, I'm a retired professional electronics design engineer and I can tell you these things are relatively simple in electronics terms.  The skill on the part of the great amp designers is in understanding the requirements and that takes direct experience in the field.)  Many should not be priced in any way at the level which they are.  You are often paying for snob value and bragging rights amongst your friends and in online forums.  Hand wiring is passe!  There is no audible benefit as modern techniques are absolutely not "tonesucking" in any way.  This factor can easily be shown on a test bench.  When hifi can be made to be 0.001% transparent easily why should circuitry of that class be detrimental to guitar work with its 5% requirements?  Adding the two in the way H&K does, completely transparent solid state control circuitry blended with tone shaping valve circuitry, is a solid approach to go down.  Others such as Marshall are now trying to gain momentum down that path.  They are still held a way behind H&K in their designs by their customer inertia.  There is no reliability benefit.  There is only the convenience factor in being able to easily fix simple problems which will occur more often.  Old "guru" techs love old technology.  It is easy to fix and gives them that "mojo cache" which translates into bucks.  Is it surprising they will suggest that the old school approach offers a "sheen of quality" in an amp even when you can hear no difference yourself?  There is - umm - errm - kudos with others stuck in that rut?  The benefit of a huge slice of "mojo"?  Are these really things which people should consider when they buy?  Shouldn't they look at accurate verifiable information and trust that over their "guitar guru" who will tell them things are so even when they can't hear it for themselves?

I had a TM 36 combo for 3 years, used weekly for 2-3+ hour practices plus gigs, with ZERO problems. I moved to the GM 40 Deluxe with two TM 1X12 cabs a year ago and love the 4 channel flexibility, global wattage selection and of course TONE. I now play the GM40D in two bands, roughly 4-5 hrs weekly practice + gigs, also with ZERO problems. The two 1x12 stacked sound awesome... and I’ve not missed my 200lb 4x12 full stack since.

I mean let’s be honest here, there is simply no replacing the awesomeness of a 4 x 12 half or full stack. Period. But for regular gigging in typical bars and clubs a single 12 speaker with the GM of 40 deluxe set at 5 or 20 W absolutely is more than enough.

I did replace the stock Celestion V 30 speakers that come with the TM 112 cabinets with warehouse guitar speakers (WGS Reaper HP is my fav) which tamed the fizziness and beefed up the low end too.

The only effect from the amp head that I use is reverb, everything else comes from my HELIX run through the FX loop.

My two cents is don’t even think about modding the amp. It is a complex beast inside and I would personally not feel comfortable having anyone digging around inside my $1200 amplifier. That said, people with more electronics confidence than I have may feel completely differently.

My only complaint about both the Tube Meister 36 and the GM40 is that they both tend to be a bit much on the high frequencies... as witnessed by my high EQ knob kept almost on zero. But again a replacement speaker can solve a significant amount of that.

Bottom line for me is I highly recommend the GM 40 with two 112 speakers stacked on top of each other. I keep one in my practice space and one at home and then just take them both out for live shows. It’s a great compact set up with way more volume then you’ll be able to use in most bars.

My first one that i got had to sent back to Sweetwater.  They sent a refurbished head without my knowledge.  Only half of the tubes lit up.  I called them and went through a series of tests and returned it to them.  When i got the new one  ..... well hell yes.....

I paired mine with 2 custom built Mesa-Boogie 1x12 mini-rectifier cabinets loaded with Celestion V30s at 16ohms (plugged in series making an 8ohm load on amp).  I stack them as a mini-stack with the slanted cab on top of the straight one.  Pure tonal bliss in my opinion.  I mainly use these in a studio.  Most places i play wouldn't need more though - especially at full 40 watts.  I wanted the mini-stack versus the 2x12 though i knew it is a bit of sacrificing some low-end.  Other that that i think its an awesome set-up.