marshall haze 40 combo

[hmstrat]

As far as the MARSHALL HAZE head goes, India is hardly a mecca for "tube" amps. The "Haze" is simply Marshall's attempt to compete with those cheap Chinese-built Orange, Vox, Egnater, etc., and other competitor's foreign-built amps...

P.S. - No offense to anybody living there, but can anybody name even a moderately successful tube-amp indigenous to India???

 

[JohnH]

Hi PacAir - I just want to say welcome, and to thankyou for a very interesting and insightful post

John

 

[pacAir]

Hi PacAir - I just want to say welcome, and to thankyou for a very interesting and insightful post

John

Thanks! I know my posts can be incomprehensible or of no interest to some but sharing information is how things get done and how we can all learn on the internet. You just drink as much as you need from the firehose!

I'll check back and post some observations on the amps sonic performance when I get the grill board re-done. I got the wood cut last night and should have the amp back together in the next week.

I have enough Marshall experience as a player to have a reasonably valid opinion on how the Haze combo will sound. I used a full stack JCM800 50w (2204 single channel head) back in the early '80s and I still own and occasionally use a pair of early & mid-80's JCM800 50W 2x12 combos (4104 single channel), a Marshall 9000 series all-tube guitar preamp and a Marshall Guvnor pedal. I am also currently rebuilding a 1979 JMP 50 2x12 combo "basket case".

Marshalls are fun (some just weigh more than others!)!


Steve

 

[pacAir]

Marshall Haze 40 Internal "Gut" Shots

Since the previous poster's internal photos are no longer available, I'll post a few of mine (hosted on my own server so they won't disappear anytime soon).

Note: The only "surface mount" components are on the plug-in DSP Effects board. The "black boxes" seen on the main board are switching relays, NOT integrated circuits.

Enjoy!


Steve

 

[spikei]

great post Steve, your amp looks like it has been to hell and back in a mixer, and I'm not sure how many amps would survive that sort of treatment, but you still find very positive things to say about the amp, most of us may have given up and topped our selves when we opened up the box. look forward to seeing your results.
im very happy with mine atm.

 

[pacAir]

Marshall Haze 40... Rebuild Almost Done!

Well, I AM a glutton for punishment! I certainly wouldn't expect most people to go this route but it's "my thing". I'd rather get the basket case and rebuild it than get a perfect one at twice the price. It's a little like being a car enthusiast who rebuilds classic automobiles except these amps are not yet classics and they are much cheaper & smaller than a car!

I just finished creating a new grill board for mine (1/2" Baltic Birch plywood) with all the holes and T-nuts in the right places and painted black. Tonight, I will be carefully removing the grill cloth and logo from the broken grill board and transferring them to the new grill board. I also had to remove a length of the white piping and re-set some of the Tolex on the front top edge of the cabinet (it has bubbled and wrinkled for some reason). Now that the glue is set I'll have to get this put back together as well before the grill board, speaker and chassis can be re-installed.

If all goes well, I ought to have the amp biased and completely reassembled sometime this weekend. Only THEN will I get to play it for real! I think it always sounds better when you have some effort invested in the amp and you know everything is as it should be and every screw is tight because you have personally checked it!


Steve

 

[pacAir]

It is Alive!

I got the whole Haze finished and reassembled this weekend. I found the clean channel to sound very good and much better than any of the previous Marshall amps I have owned (primarily JCM800 vintage).

The drive channel surprised me at being so low in gain that even with the gain turned up to 10, it was only hinting at what it might sound like with a pedal ahead of it. Is this lower-gain drive channel normal or do I have a bad 12AX7? I was expecting something a bit higher gain than this but I was wondering what the experience has been with other owners. I wakes up a bit with a Tube Screamer ahead of it but this particular amp is surprisingly docile on the gain channel without the pedal.

I'm beginning to think there is one more problem to locate! Perhaps the second tube got damaged by the same thing that annihilated the phase-splitter tube (the loose speaker).

The built-in effects are serviceable but not as easily configured as a 3-knob pedal is. This is one area where the Fender Deluxe VM is better. On the VM amps the effects are individually switchable on the included footswitch (4-button) and are adjusted in the traditional 3-knob fashion.


Steve

 

[tibboh]

Thanks, the guy I am taking it to is factory certified to repair every amp I have ever heard of and a few I haven't so, if it can be fixed he can do it!
Just a little disturbing as this is it's second trip in the 3 weeks I have owned it!!! first was for a bad 12AX7.

Glad to hear it was your choice to send it back not marshall's. Rather have an amp that has had this stuff fixed then take the chance on starting all over with a new one.

Thanks for replying. I will post whatever I learn.

srv

Bought my Haze 40 last month - popping back (when switching channels) got quite bad once warmed up. Emailed Marshall and they recommended that I send it back via dealer. Had it back after 2 weeks and fault has been rectified. Excellent customer service in my view

 

[Ernie]

Hey, I noticed you've had to reply tubes...

My Haze 40, after less that 10 hours use, lost the boost channel. It pops a little, sizzles like bacon frying, and wehn turned all the way up, you can barely hear the guitar. Sounds like its far, far away.

I am new to this -- can you advise -- do the symptoms mentioned here sound like a blown tube? Are there differnent tubes for each channel, since the clean channel is working very well?

 

[pacAir]

Hey, I noticed you've had to reply tubes...

My Haze 40, after less that 10 hours use, lost the boost channel. It pops a little, sizzles like bacon frying, and wehn turned all the way up, you can barely hear the guitar. Sounds like its far, far away.

I am new to this -- can you advise -- do the symptoms mentioned here sound like a blown tube? Are there differnent tubes for each channel, since the clean channel is working very well?

That sounds like and could be a tube failure. The preamp tube farthest away from the output tubes (far-right when looking at the back of the amp) should be input stage and clean channel. The second preamp tube should be the distortion channel and tone control stage and the third ECC83/12AX7 tube is most likely the phase-splitter that drives the push-pull output tubes. I say "should be" because this is a typical configuration and the Haze schematics do not yet seem to be available.

If you take the back off (unplugged of course) you can reach behind the chassis and find the tubes. The first tube (input) has a metal shield over it. The second tube from the right is probably the culprit if a tube is at fault. The factory ECC83 tubes in the Haze don't impress me as being of high quality manufacture (they don't look like a quality assembly inside when compared to the JJ or Electro-Harmonix/Sovtek tubes I had handy) and I have heard of a number of people who have had these tubes fail.


Steve

 

[pacAir]

Well, now that I have had some time to take the Haze 40 out into the real world of local live music and flog it a bit I can report on how the amp sounds and works (with my Stratocaster).

I have used the amp both clean and dirty in a variety of venues and with a variety of musical genres. I found that the clean channel to be quite adequate to cover anything type of music I normally play and this is a compliment! It does not sound as good as some Fenders and most Music Man amps in the clean department, but it is clean and sparkly enough to get the job done for me.

I still find that the barefoot drive channel (no option buttons depressed) is a bit lacking in gain for use with a Stratocaster w/ single coil pickups unless driven by a pedal. It is probably more inspiring with a Les Paul. I'm using an Ibanez TS-808 Tube Screamer re-issue to bulk things up a bit and it was MADE for this amp. I haven't been using this pedal with my other amps because I didn't care for the resulting tone but it LOVES the Haze.

I can get some beef out the amp without a pedal if I turn on the Drive Boost. However, this changes the tonality of the amp (muddies-up) so I have to compensate by using the bridge pickup and turn on the Bright switch. In this configuration the Drive channel reminds me of my '80s JCM800 4104 combo. The TS-808 will push this over-the-top quite nicely for leads but is limited in dynamics and level at near maximum output.

Unfortunately, because the Bright switch is global and not restricted to the drive channel, my clean now has too much Treble and with only one set of global tone controls I cannot compensate on the amp. What I have to do is roll off the guitar's tone control for Clean and roll it back up for the Drive channel. A small price to pay for tone!

My biggest complaint with the amp has got to be with the size of the filter caps and the amount of iron in the transformers. The amp sounds fantastic until I have to really push it hard for a lead and get it over 3 or 4 other band members in a club environment. The Haze starts to sound a bit thin and strained when pushed up to its limit of output. My 50 watt JCM800 combo (which weighs about twice as much as the Haze) will not only handle it but ask for more! A lot of the extra weight is in the power supply and magnetics components. There is no real substitute for "iron"!

I use the Haze with a 16-ohm 1-12 external cab (connected to a custom speaker jack wired in parallel with the internal speaker and both plugged into the 8-ohm output jack). This arrangement artificially seems to help the anemic full-bore lead tone because of the low-end output of the closed-back extension cab with dissimilar speaker.

I find that the effects are quite usable for a grab-n-go style of lightweight amp and I have gigged with nothing more than my Strat, the Haze 40, a tuner and the TS-808 and did not wish I had anything else. For small club gigs or jams where size and complexity work against you, this is a sweet set-up.

The older I get, the more I appreciate simplicity and lightweight.

'Nuff Said!


Steve

 

[mtelep]

Hi all,
I own one of the Haze 40 combo for a few days and have a few questions.
First - I am not able to completely mute the normal/clean channel. I hear crosstalks or overhearings (don't know the right name - will be grateful for a clue) from the driven channel that mess up the clean sound. Curious thing is the clicks are audible even when the driven channel is completely muted. Setting of gain and level knobs affects level and tone of these crosstalks, but doesn't eliminate them fully.

Another question is about switching into standby. It's my first valve amp and i just don't know - sometimes it causes quite loud clicks. Is this normal behaviour?

And the last one - I know tubes have its own rights, but I think noise levels are too high. Even on clean channel - lots of hiss and rumble (on driven one) - I have well grounded electrical installation at home and my solid state amps were totally noiseless.

I will be grateful for your feedback in this matter.

Beside this - I really like its clean tones. I have mahogany epiphone explorer with set of emg 81 (bridge) and 89 (neck) powered with 2*9V batteries, so I am using bright switch often.
Driven tones are a little bit muddy, and a boosted gain could have more 'bite'
These are my observations from first days of playing it around.

Edit: here's thread about my first question - looks like I am not the only one having this issue, but it seems to be very rare
http://www.marshallforum.com/workbench/8553-haze-40-bleed.html

 

[pacAir]

Interesting, I'll have to try this on mine with my Haze 40 with a Les Paul. I normally play with a Stratocaster and have not noticed this phenomenon. Of course, I also set up the gain channel with BOOST and BRIGHT turned on and the gain only turned up to 9 or 10 o'clock I seem to recall.

Steve

 

[mtelep]

We have checked with another Haze 40 combo and the behaviour was the same. So it looks like faulty batch...
I managed to replace it with MA50C, the DSP board was not necessary for me, and more gain - yes

 

[gastoon]

do you think that the ma-50c is better than de haze 40??
i want to buy one of this amp and need information
thank

 

[danielgoba84]

Re: Marshall Haze 40 Footswitch Problem & Tech Review

Marshall MHZ40C Haze
Repair Narrative 11/2/09

Electronics Problem

Regardless of WHICH effect was invoked (delay, chorus, vibe), turning one or both of the adjustment controls past about 1 o'clock started causing the effects and the front-panel LED indicator to turn on and off in concert with the speed/modulation setting (more or less)! It was as if the modulation signal was turning the switching on and off! As the amp warmed, I started to get a bunch of clicking relays to go along with the flashing LED! Not good, an out-of-control mode of functionality!

I connected the external footswitch and found that while switching the effects button on and off turned the foot pedal's Effects LED on and off, there was NO switching occurring in the amp itself! The footswitch was NOT controlling the effects at all (although channel-switching was correct). I did some signal tracing to confirm that the footswitch itself was working fine and that the problem was electronic in nature.

I deduced that there might be a microcontroller somewhere doing all the relay switching (rather than a hard-wired state-machine) and I found it living on the main board, out of sight (UNDER the DSP Effects board). I traced the final destination of both footswitches to their respective controller pins (pin 2 for effects, pin 4 for channel-switching). I found the OFF state for the channel-switching function was 3.6Vdc, while the same condition in the effects-switching circuit only yielded a 2.9Vdc reading. THIS was ultimately the golden clue!

After measuring and comparing the surrounding components I found a voltage-dropping resistor in the channel-switching circuit that was 4.7k, while the same component in the effects-switching circuit was 27K! An incorrect resistor value had been installed at the factory! I changed R54 to the correct 4.7K value and the problems disappeared! All the amp switching circuits started to work as expected with no surprises. I also re-seated the microcontroller as it was not fully inserted into its socket.

It is my belief that this resistor may be the culprit involved in the footswitch "popping" so many owners have complained about. If you have a local tech, have him check the value of R54. It is located under the DSP Effects board (which must be removed) and is just forward of the microcontroller chip (socketed and with a handwritten firmware label on top of it).

As soon as I can get the cabinet and speaker issue resolved, I'll be able to give the amp a proper sonic evaluation.


Steve

So, Steve, you now have the schematics... could you tell us if you found any error in it? as you talk of a mistaken resistor i wonder there's any mod we could do to fix the popping or to improve the sound of the Haze amp...

could you guide me or recommend me any page about biasing this amp? i had to change the tubes .. and i feel the sound of the amp could be better... any help is appreciated.. altough you have helped a lot already with your posts... is there any page where we can find more of your jobs or knowledge??
thanks in advance

Daniel

 

[Bonedaddio]

This is a great thread! Awesome damage, awesome reconstruction.
I love my Haze 40, had it for almost a year now. It's been used a fair amount for practices and gigs.
I made the two cap mods, clipped and lifted one leg on the C73 and paralleled an 820pf cap on C72 per this thread: http://www.marshallforum.com/workbench/14227-does-anyone-know-about-mods-haze.html#post133721. The amp sounded a lot better, really sweet, and THEN...
All of a sudden the amp makes really strange noises, and makes a lot of noise when you tap on the chassis or even the amp, intermittently. Does not sound good. I swapped out preamp tubes one at a time, and that's not it.
It seems that one of the power tubes is making some noise...
STRANGEST OF ALL, if I put the amp on it's side, it doesn't do it at all.
Any body got any suggestions??
I think it's the power tube. I also noticed they're not matched, their actually slightly different heights ever???!!

 

[Bonedaddio]

PacAir, can you help with biasing the power tubes on the Haze 40?
The schematic is here: Marshall MHZ40C Haze 40 Schematic Anyone?

-It looks to me like I would check bias values at Con3, between pins 1 & 2 and between 2 & 3.
-The values I'm getting (DCA scale, 200u setting on the dial) are 26.9, and 43.8, respectively.
-If I'm not completely wrong, then I would adjust VR1 and VR2 to get the 39mv value for each (the 39mv is on the schematic at Con3.

Please, some one tell me if I've got this all wrong.

It seems logical that they'd be quite different, as the amp came from the factory with two completely different umatched EL24's in it... TAD "1" and TAD "2" on the labels and they're actually different heights...
Help would be greatly appreciated!
Thanks,

Les

 

[jamesm]

You are correct about setting the bias - 39mV on both sides.

James

 

[MKB]

Les, the two bias controls are a bit interactive, you have to go back and forth between the two to get them balanced (you usually can't set just one then the other and expect both to be right). Also note the bias current is for the stock Marshall tubes, I had to set mine a bit hotter with Groove Tube E34L's (45mV IIRC) to get rid of the crossover notch.