All channels very fizzy apart from clean if gain knob goes past 9 using red box with master at noon?

I've owned this amp for a couple of months naw and I really like all it's features it's the first valve amp I've owned so I'm a bit of a noob to say the least I don't own a cab at the moment and I got this for mainly using the red box but if I'm on any channel other than clean and I turn the gain past 9 it's a very fizzy sound to the point were it's not even a useable sound and that's with the master just before noon and the volume just b4 noon even on the crunch channel as soon as the gain goes up past a quater it sounds really fizzy I don't know whether it's because I'm not using a cab or sum kind of rookie mistake but I've had it a couple of months so I've had plenty of time to tweet but can't seem to find a way round it is this normal behavior for this amp?

I have just come out of the problem you describe, the H&K amps have a "fizzy" top end if not treated right, (I even used the same word as yourself to describe it).

So how are you listening?  Are you putting the GM into Silent mode and feeding the red box output into an amplified system with its own speakers or headphones, or are you playing audibly using your standard speaker cab but lifting the Red Box signal to a desk?

Well, for what it's worth, here is my dummy's eye view of the problem, or, "Things I have learned playing a fizzy TM36":

Start with using your guitar's tone controls.  The TM and GM respond wonderfully to that in a way no other amp has for me.  You can take off a lot of top end stridency with a tweak of the little finger before making much tonal difference at all.

Guitars are important.  A full on PRS may be more sensitive to this than a 335.

Speakers are hugely important.  e.g. Vintage30s NO!  G12M Greenbacks YES! And try changing the speaker cab emulator, it has the Classic/Modern selection available.

Valves make a significant difference.  Have you replaced the valves or are you using the stock ones?  I'm a big poohpooher of most things "mojo" but, in the case of valves, I proved despite myself that what people advise with these components at least is correct, they DO sound different.  The stock valves I find are very open to harshness at the top end.  (This might even make them a better valve in electrical terms with a wider frequency response so "Huh, using cheap valves eh?" comments might be said to not apply.)

The tone controls on the TM/GM are a mystery to me!  They say they interact like any tone stack but I find they interact like no other tone stack!  Some of it is counter intuitive, backing off on the middle control to allow the bass control to become effective is not what I would call logical!  It may help if you really spend time setting them up to minimise the brittle upper end.  And play with the Presence and Resonance controls.  Trying them backed off might help.

If it applies in your setup, also play with the power soak settings.  It's useful to note how much playing the amp on different power levels with the controls reset can alter your sound.

Finally consider this.  If you bought a 3 channel Marshall which has Clean (Country), Crunch (Blues), and Dirty (Metal) channels and you never used the Dirty channel because you don't play Metal, you wouldn't think anything of it.  The amp is just set up to offer more sounds to a wider range of people.  When you are setting up the tone of your GM, if you are getting the sounds you want at lower settings then stop there.  I know it may seem to be extreme to say just don't set it above 1/4 but I found the same thing.  I play Classic Rock and have no interest in ear bleeding teeth shattering metal sounds, but they have to be there in the amp to offer it to more customers.  Since sorting out the above details and not looking at where controls were set, I have never found that I can't get close to the sound I want with sufficient volume and to spare.  I don't worry where the controls are set now as long as it gives me my tone at high enough volume.  And space in the room alters that fizziness too.  The amp seems to sound much smoother and more balanced in a large room where you can crank it a bit more.

But of course, you may be only using it via the Red Box and never putting out sounds through a speaker directly so some of the above won't apply.  Hopefully others will put out their own findings and we can get you on the track.

Just to clarify, you're strictly using the redbox out, right? I think I can help. What are you connecting it to? A recording interface? A PA system? The main thing to know, is that the Redbox output is LINE LEVEL... if you try connecting it to a mic level or instrument level input, the clean channel will sound ok but any of the drive channels will sound fizzy/harsh. A line level signal is too hot for a mic/instrument input. This is a rookie mistake that I'm not ashamed to admit I made, back in the day.

You can do one of two things - make sure to connect it to a LINE LEVEL input; or, if your device does not have that capability (like my recording interface), just attenuate the signal ~40dB. That's what I have to do for my Presonus Audiobox recording interface. There are lots of inline attenuators out there - search ebay for "xlr attenuator". I use the kind that looks like a 12" xlr cable, I find them easier to use than the typical metal tube style.

edited to add: here's the one I use: http://www.ebay.com/itm/Balanced-Line-to-Mic-level-converter-attenuator-pad-XLR-/200810579560?pt=LH_DefaultDomain_0&hash=item2ec13e4668

Hi mate thanks for the reply I'm using the red box out in to a audio interface and then through sum monitors so I can't change to 18 or 36 wat valves are the stock ones but I'm considering changing them at sum point I also play blues /hard rock sorta stuff and I am getting to the point were I'm finally getting sum usable sounds but it just seemed strange to me that I was having to dial everything bak so far when I first got the amp I had gain volume and master all up above noon and I thought to myself this is a very fizzy amp but like I said I'm starting to get sum very usable sounds but that sound when every thing is cranked up I don't even no haw sumone who's in to metal can use that sound but mabie if I was runing it through a cab it would take a bit of the harshness away but I'm hoping I can get by with out one because I don't own a car and it's really handy when I go 4 jams to just pick the amp up and my guitar there's just no way I'd b able to transport a cab at the mo what you've said kind of puts me at ease if your sound sounds good with gain on quater then that's were it's staying just didn't no whether it was sumthing I was doing or not doing I've played guitar for 10 years but just never owned a valve so it's a bit of a learning curve cheers
If anyone else would like to chime in on haw there getting there tone/ distortion feel free it would b interesting 2 compare haw other people are setting there gm36 up

Hi gravy I'm using a focusrite Scarlett and I'm pretty sure it has line level but irk check it when I get chance when I look at the audio signal in my DAW it isn't in the red

And 4got to mention my guitars a gibson nighthawk

I`m right there with Gravy. Anything past about 9:00 on the master and it overloads the input of my PreSonus Audiobox, even with the trim dialed all the way back. Your DAW might not be going into the red, but you may be feeding it a horribly clipped signal.

Hi voodoo jef I got a reamp just to check it takes line level dawn to instrument level and it was still the same so I don't think it's overloading the focusrite I have managed to more or less sort it out by backing the resonance knob dawn to 9 on all my settings and the gain never goes above 9 with these settings I can crank the master all the way up with no fizz (I think my guitar must just be super hot ) I can get most of the sounds I like using these settings there's just the odd time when I wish I could just crank the gain a little more but never mind if I had a cab mabi things would be different but it just isn't a option at the moment I'm still happy with the amp though

I see a lot of responses of this type on forums, and I make a few myself so I understand where they are coming from.  If the problem is that you don't like the sound when your gain is past 9:00 but like it when it is around there then - - - errm - - - why not - - - just don't turn it up past that!  If you were playing amplified acoustic music with only the Clean channel would you feel uncomfortable when it sounded too rough on the Crunch,Lead or Ultra channel so you never used them?  Of course you wouldn't, you would just use it where it sounds right.  Do the same here.

I can say this as I have the same feeling as yourself, I am constantly trying to tame the amount of overdrive I get with a LP Trad.  I really want to make it sound less "90s US Big Blowing Hair Spandex Pants Drunk As A Skunk Stadium Rock" and a lot more "70s British Straggly Hair Bell Bottom Jeans Stoned Slumped On Speaker Cabinet Rock".  I can get it if use the Crunch/Lead and I more or less dime the Master and cut the Gain right back around, surprise, 9:00 or 10:00.  But if I do that it just plain looks odd and kind of, well, "weedy" to me, and there seems to be so much more control I am wasting.  That unused area is there for the other freaks who want to rip their eardrums out at the root and slice the features off the front 5 rows of the audience, (and good luck to them), but it serves no purpose for me.  I now try to look on it in the same way as why every car sold has a cigarette lighter even though the majority of people don't smoke!  It's there only to give the car appeal for the few chokey smokestick victims still left needing it.  

I would really try to get to the point where you find your settings by shutting your eyes and turning the knobs while you listen with your ears.  The important thing is, can you dial in the sounds you want to use.  If you can then the GM36 is your dream machine, if not it's an expensive paperweight.  Change it out!  (But you don't sound like you need to do that, just adjust your perspective like a lot of us have had to learn to do.)

One area I would read up on, but VERY carefully, is valve replacement.  Now I am a firm poohpooher of magic mojo components, but one I have had to admit makes a difference is the valve!  I have changed out my original Chinese valves for Electro Harmonix in V1 and V2, JJ ECC83S in V3 (S denotes balanced pair within the valve), and JJ EL34s in the power amp.  It tames a lot of the initial fizz I was experiencing.  Since then I have tried to reduce the gain to get closer to my smoother classic overdrive by adding a Mullard 12AT7WA in V3.  These valves, (must be Mullard NOS), are recommended for Phase Splitters as reducing gain without removing lower frequency weight as many 12AT7s are said to do.  I then put the JJ ECC83S into V1 to try against the Electro Harmonix I had in there.  It does seem to be a bit less strident though it's early days yet and I will need to compare more before I'm satisfied there is a genuine difference and not just my enthusiasm and imagination.  If you try this DO look into the posts of technical valve guys on other forums even though you may not understand everything they post.  There is nothing more irritating than to see someone say "go fur a Nakamichi ECC82.5 mate dogz bolox mad my voltan bs30 sound lik a marshul", as though that statement carries any genuine proof that he hears what he says.  It's an expensive area to just jump in and buy on the strength of someone's one line paragraph!

Hope it works out and you can see it this way.

I think your right mate if you can dial in the sounds you like then why worry I think for me at first it was the fact I'd never owned a valve amp b4 and every other amp I've owned I've always cranked them pretty high and as soon as I got the grand meister I set the dials were I'd normally hav them on other amps and incounterd the fizz it was onley when I came on this fourm and someone recommended dropping the resonance and gain that I started to get some sounds that I liked and it put my mind at rest when I realised a lot of other people were runing the amp with similar settings to get there hard rock sounds. I will try swapping the tubes out at sum point but my bank account is still recovering from the grandmeister and the strymon bigsky that I got at the same time ha ha thanks for every one who's posted on this thread cos I'm a total noob with amps and I was close to getting rid of it but 3 months after my purchase I think I'm finaly a happy customer

Great news. That's right on the button! We've all been there. Stick around here and help the next guys in.