marshall haze 40 combo

[JohnH]

I think it is absolutely great that jamesm comes on this forum to support and explain the amp that he designed - and I think it is starting to become clear that this amp is well designed indeed. +++++!

John

 

[jcmjmp]

I think it is absolutely great that jamesm comes on this forum to support and explain the amp that he designed - and I think it is starting to become clear that this amp is well designed indeed. +++++!

John

Huh? jamesm designed the Haze? And his coming on this forum automatically makes the amp "well designed"?

Ths DSP stuff is all over the new Marshall gear. From a design perspective, the designers have little say in terms of whether DSP make it in or not (Ref. Vintage Modern). The product has to have x amount of feature at whatever price point they set. End of discussion. The Haze could have been a great little amp if htey had ditched the on-board effects crap. It just cheapens the whole product IMO.

If I wanted DSP and ADA conversion, I'd get a POD, some rack gear or whatever... Typically, you buy a tube amp because you appreciate 100% analog.

Is the DSP bypassable?

Hey, there's nothing wrong with DSP, BTW. It has its applications and they can be real powerful devices.

 

[jcmjmp]

Look at the Vox AC30CC for example. It's modern, mass produced in China, and uses a PCB, but anybody could easily pick out the components on that board. I'm definitely not buying a Haze, that thing looks like it could catch fire!

Yup - Excellent example. Solid product, awesome tone, quality PCBs and parts thorughout (except for that paper thin tolex).

I love my AC30CC2

 

[JohnH]

As has been stated in many threads including this one and in Marshall literature, the digital effects are completely bypassable. James states above that when effects are bypassed, the signal path is 100% tube.

 

[Fretburner]

UPDATE: Used it last night with the band. It sounds awesome! I'm very satisfied!

 

[Ken]

Huh? jamesm designed the Haze? And his coming on this forum automatically makes the amp "well designed"?

Ths DSP stuff is all over the new Marshall gear. From a design perspective, the designers have little say in terms of whether DSP make it in or not (Ref. Vintage Modern). The product has to have x amount of feature at whatever price point they set. End of discussion. The Haze could have been a great little amp if htey had ditched the on-board effects crap. It just cheapens the whole product IMO.

.

This leads one to believe Marshall's marketing department has more influence than the engineers, which is good for profits but bad for more discerning customers. Marshall obviously had this amp designed for younger players with limited budgets, who would want the most bang for their buck.

Older musicians and pros with unlimited budgets want a different kind of product. They want simplicity from the amp and will add on whatever effects they decide they need. Marshall obviously doesn't think they'd sell as many amps taking this approach and they may be right!

The fact all that extra stuff is out of the signal path when bypassed is a smart compromise and a good design. The negative comments about all the electronics aren't warrented when one learns that. I myself went "yipe"...so Marshall should really emphasize that the signal path is pure tube!

Ken

 

[BCnSTL]

Found this new-ish clip on YouTube: [ame=http://www.youtube.com/watch?v=pNs-dXLrJpQ&feature=channel_page]YouTube - Ken Stanton Music Marshall Haze Demo[/ame]

I'd say it's a decent representation of what the Haze 15 sounds like IME.

 

[the_best_of_fools]

How would you compare the Haze 15 to the 40? Is there a big difference in sound? I haven't had a chance to try one out yet. I'm really looking for that JCM800 sound and I'd think the 40 would come closer with its 3xECC83 and 2xEL34. Or am I wrong?

Also, the fact that there's no Master volume is kind of a turn off for me since I don't see the purpose of building a practice amp that can't be played at low volume and still offer all the signature sounds it was designed for.

Thanks,
tbof

 

[MajorWatt]

Sounds pretty cool... Have to test drive one soon.

 

[srv]

Heres a little background on the internals of the Haze.

The surface mount components you see are all on one, small effects DSP, much like you would find in a delay or reverb pedal. From a servicing point of view, these rarely go wrong, but can be replace with a new plug in board, so should be no more complicated to replace than a valve.

Apart from that, there are only 2 more integrated circuits. These control the switching. The other black boxes you can see are relays, which switch the signals to change channels. These contain the same "stuff" as a switch on the front panel, but can be changed by the footswitch. Each of these is controlled by a transistor, but that is not in the signal path.

With the effects and loop switched off, the signal never goes near a lump of silicon.

What do you know about the loud pop I am now experiencing when switching channels? I have not tried completely turning off the effects section but will tonight. This seems to be a fairly widespread problem if you check the forums.
I have already had to take the amp in to have one of the 12AX7's replaced. Talk on the forums is that the pop leads to death of the amp. Will my very capable repair guy be able to get the info \ parts to fix this? Or is a return to the factory it's only hope of a happy healthy life?

Not what I expected when I bought an amp with the Marshall logo.

Glad I still have a Vox VT30 so I don't have to go acoustic!

 

[BCnSTL]

How would you compare the Haze 15 to the 40?

I don't know honestly. In my experience there can be fairly big variations in how different power-tube configurations/types can sound so I'm hesitant to state anything about them categorically. The Haze 15 sounds, well, classically "Marshally" to me. Like I've said before - the "Marshall" sound covers a LOT of ground. Think classic/hard rock Marshall, not detuned heavy-metal Marshall. The Haze 15 is somewhere between a Plexi and a JCM800 - it has an overall 'softer' distortion like the plexi but with a tighter low-end. That's just my impression and I am NOT a credible Marshall afficiando.

Also, the fact that there's no Master volume is kind of a turn off for me since I don't see the purpose of building a practice amp that can't be played at low volume and still offer all the signature sounds it was designed for.

Thanks,
tbof

There is a master volume on the dirty channel. The interaction between the gain and volume controls lets you get a nice overdrive happening at very reasonable volume levels. However, the amp comes alive when you push the output section a bit - say when the volume is on 3 or higher, and that's pretty loud but certainly significantly less so than a 50 or 100 watt amplifier.

Personally, I think all the angst and criticism about these amps amounts to fetishism. They are made with MDF not birch plywood enclosures, they are not hand-wired point-to-point. They ARE inexpensive and sound great and yet do not diminish the cachet and lust-factor associated with the higher-end Marshall amps.

 

[spikei]

I'm one of those older guys who doesn't want to brake my back carrying an amp around anymore, i want good on board fx and not have to fuss about tap dancing on stage, and i wanted the valve sound of my old jmp 50 combo, i got all in the haze 40 w combo. good clean, crunch and overdrive sound from a rasonable priced amp.for pubs and clubs its a winner. my only concern is reliability as i have already had to have the popping between channel sorted (they sent me a new amp in three days)
only time will tell if this is a big seller, but its got what i want from a small amp.

PS one other issue is you can connect up to a cab but you fave to disconnect the internal speaker, which to me is crazy.

 

[srv]

What did they do to fix the popping?
Mine is doing that and any information I could pass on to the tech might shorten my time with out the amp.

Thanks

 

[srv]

I'm one of those older guys who doesn't want to brake my back carrying an amp around anymore, i want good on board fx and not have to fuss about tap dancing on stage, and i wanted the valve sound of my old jmp 50 combo, i got all in the haze 40 w combo. good clean, crunch and overdrive sound from a rasonable priced amp.for pubs and clubs its a winner. my only concern is reliability as i have already had to have the popping between channel sorted (they sent me a new amp in three days)
only time will tell if this is a big seller, but its got what i want from a small amp.

PS one other issue is you can connect up to a cab but you fave to disconnect the internal speaker, which to me is crazy.

So the fix was to send you a new amp, to bad I was hoping it could be fixed.

 

[MajorWatt]

So the fix was to send you a new amp, to bad I was hoping it could be fixed.

Having done factory warranty repairs in the past, I know sometimes it's cheaper and easier for them to just replace rather than repair. This tells you something about the quality of the design and components. At this stage anyway.

 

[spikei]

they sent a new amp because it was only a day after i bought it and i insisted it was sorted, i was not about to wait about for some one to get it fixed. SRV if yours in under warranty and you got it from a supplier dont leave it as it is get it sorted, marshalls have a three year warranty (with clause). this is a well known problem get them to sort it. even if its second hand i would have a go at them.
good luck
ps if it helps i think it was resisters

 

[srv]

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

 

[tarznamps]

A few post seem to imply that Marshall's marketing dept. controls the designs of a new Marshall amp. That is rubish.

Just because you don't like the Haze series because it isn't a $5,000 handwired super Marshall doesn't mean that it isn't needed in the market place. Why would anyone imply that an amp should not exists because they don't like or need it?

Marshall has a great line-up of amps for all styles and price points. Pick the one or two or three that you want and don't worry about the rest!

 

[BCnSTL]

I went with the Haze 15 because: a) I wanted the protability and versatility of a head/cab setup b) I didn't want 40 watts of power and c) In this case I prefer the smooth overdrive of the 6V6 vs EL power tubes - sacrilege I know.

Related aside: weren't the very first Marshall amps 6L6 based?

 

[pacAir]

Marshall Haze 40 Footswitch Problem & Tech Review

Marshall MHZ40C Haze
Repair Narrative 11/2/09


Up front, let me state that I have played guitar for over 40 years and have repaired amps and worked in electronics design and manufacturing for over 35 years. I am not a vintage "snob" or a newbie. I am a technically informed user who was attracted to the Haze for its potential, small size and light weight. What follows is my story, findings and opinion.

I bought a Marshall Haze 40 combo "kit" from a major online retailer. It is a "kit" because it didn't survive its return shipping from the customer. It was returned then shipped out to me (apparently without any further handling or repackaging). This amp could have had 3 transcontinental UPS Ground rides!

Even though the original packaging material was all there, the amp was pretty much a basket-case when it arrived here. The results of my troubleshooting, repairs and rebuild should shed some light on a number of design and construction issues discussed in this forum, this thread and elsewhere.

Apparently, an existing electronic problem caused the first owner to return it and the subsequent physical shipping damage to the amp led it to find a home with me at a much reduced price. I'll cover the physical damage and construction of the amp first, then cover the electronic problem and design observations.


Cabinet

The main physical failure on this amp (and on at least a few others from what I have seen and read) is when it encounters a good drop or other mistreatment during shipping. While the cabinet itself may be made of MDF (I have not confirmed this but it appears to be so), the grill board is made of 9/16" particle board (or "chip board" as it may also be referred to).

My amp arrived with the loudspeaker completely detached from the grill board! Even though T-Nuts were used to mount the speaker, large chunks of particle board were still mounted to the speaker at the T-Nut locations! The remaining grill board was missing these chunks and has completely de-laminated in several places. It looked like a small bomb went off! The cabinet was filled with splinters, chunks and sawdust from this failure.

The 12AX7 phase-splitter tube (I assume, as a schematic does not seem to be available online) was completely naked (no glass) because the rogue speaker took it out. Also, the magnet of the speaker had some small chips missing off the edges due to the speaker's repeated collisions with the chassis AND the output transformer! The output transformer mounting bracket (very lightweight and cheap) was almost completely separated from the chassis and was dangling at a 45 degree angle. The chassis, while scratched and marked-up, was not otherwise damaged.

The cabinet was otherwise undamaged (except for a few small gouges and scratches along with some lifting and wrinkling of the Tolex on the top front lip which I will have to address). The grill board will have to be replaced and I will make a replacement out of the best plywood I can get in order to have a more bulletproof unit.


Amp Chassis

I repaired the output transformer mounting problem by crafting a couple of "bar washers" to fit the footprint of the transformer mounting brackets (after these were hammered back into shape, sort of). Once the output transformer mounting issue was repaired, the broken ECC83 (I assume) was replaced with a Tung-Sol 12AX7 I had handy. The amp chassis was now ready to be plugged in and tested.

The amp came alive on the bench and put out an honest 40 watts RMS. Both channels worked as advertised and channel switching from the front panel seemed to be fine. While the effects and its front-panel switching arrangement seemed to work at first, I noticed a strange problem.


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.


MHZ40C Design, Quality and Conclusions

Let me start by stating that overall I was favorably impressed with the amp's design and most of the basic construction qualities. For a low-priced (for Marshall) amplifier, it uses a good quality double-sided PCB and a nice heavy-duty chassis in a reasonably strong cabinet (not including the grill board). The quality of the workmanship inside is BETTER than I expected... the wire dress, soldering and attention to most details is quite good.

The first place that showed "too many pennies pinched" is in the choice of grill board materials. DO NOT STRAY FROM quality PLYWOOD PLEASE! 13-ply Baltic Birch if you can get it! The ease with which this grill board was destroyed (without effecting anything else) surely paints this squarely in the "weak link" corner! Who knows, humid conditions in India may well give this problem a head start (this material tends to absorb moisture and turn to oatmeal given half a chance).

The packaging material was better than some but could still use improvement. The amps need to be cradled and shock-mounted, not merely "suspended" with destructable styrofoam. Also, the transformers are certainly inexpensive but appear to be adequate for this level of amp and output power.

The next area that could have been better was the front-panel pots, but the jury is still out on the longevity factor. At least these pots have sturdy mounts to protect and strengthen them.

The wrong resistor in the footswitch circuit is probably due to a human error or typography/transcription error in a BOM. This is a teething problem that will disappear once it get sorted out at the factory. It does not appear to be a design problem (although without a printed schematic I couldn't say that for sure). I hope not too many amps suffer from this particular problem. It isn't difficult to fix but the shipping, handling and assembly/disassembly are all out of proportion to the tenth-of-a-penny resistor at the heart of the problem.

The opinions offered above are done so without listening to the amp at all (only observing its performance visually on an oscilloscope and eyeballs on the product's manufacturing qualities). I would have personally preferred more of an open back on this amp but the semi-closed back may improve the tone. I won't know until I can get a complete cab to wrap around this chassis!

With the immediate problems fixed, the amp can then be judged by its sonic performance. Contray to some people's opinion, I see a lot more to be happy about here than to be afraid of. I think this may be a great lightweight alternative that many of us could make good use of as long as it has a base of reliability we can trust.

As I see it, there are two standout design features:

1. The "Effects per Channel" memory (the effects previously used on the Clean channel, Gain channel and "Boosted Gain" channel are remembered individually and recalled when that "channel" is selected). This feature is unique in its price range.

2. The fact that when the DSP Effects are shut off and the rear-panel effects loop is bypassed (by the switch next to the jacks), the Haze 40 combo presents an ALL TUBE signal path. This is NOT the case with the Fender Deluxe VM, a very good amp in the same category.

Coupled with the small size and light weight, I think this makes the amp's configuration flexible enough to meet the needs of a variety of players. I look forward to playing through it live as soon as I can get that new grill board created and installed.


Steve