Marshall Haze 15 - Everything you wanted to know...

Discussion in 'Marshall Amps' started by Micky, Oct 28, 2014.

  1. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    Greetings!

    The Haze 15 is a sweet little head, often overlooked and now out of production.
    As such, even though this little head was made in India, it is destined to become very rare, very quickly. James M at Marshall helped design this amp, and he is a prominent figure there and occasionally posts here and at the road house.

    To call this amp 'little' is an understatement, and even though it is enclosed in a small headshell, there is nothing 'little' about the sound that comes out of this head. While small in size, it is large in tone, and very well suited to many different types of music.

    I write this in hopes that others can contribute their experiences to this thread, and we can build up a repository of information that we can refer to as time goes on. What actually prompted me to write this was that it was time to re-tube the little beast, and while I had the chassis out I decided to snap a few quick shots and post them here.

    As with any re-tube, I needed to re-bias the new tubes so it was time to take a few measurements after I got the chassis out. Here is a shot of the connector where bias measurements are taken:

    [​IMG]

    You can clearly see the CON2 labling, the center pin is ground and the left pin voltage is adjusted by the left bias pot, and vice versa. Here is a shot of the bias pots, VR10 & VR11:

    [​IMG]

    As you can see, there was a bit of 'loctite' on the pots, in order to bias new tubes you must 'break the seal' so to speak, and as this was the first time I had messed with it, it is no longer a virgin...

    The bias was set cold from the factory, 14mv on one side and 16mv on the other. The OEM Marshall-branded tubes are believed to be JJ's and while they sounded pretty good, I decided to pull them while they were still strong as to have a spare set. I cannot stress the need for a spare set enough. Anyone who regularly gigs or records with their amp needs a spare set.

    More later...
     
  2. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    The Haze 15 has only 2 preamp tubes, as V3 is considered part of the power section as the phase inverter. Here are a couple shots of the layout:

    [​IMG]

    [​IMG]

    And here is a shot of the underside:

    [​IMG]

    As you can see, this is a typical PC board layout, with the tube sockets soldered to the PC board, and the board is very closely mounted to the chassis so the sockets appear to be chassis mounted. In all reality they are very tall sockets...
     
  3. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    Quality of construction here is top notch, anyone leery of an overseas-made amp should reconsider their opinion. I know I did. What really caught my eye was the black powder-coated chassis, it really sets off the contrast between the components and the chassis. The grate on the back of the amp is also black, not the traditional gold or brass-plated screen to protect the tubes.

    These are the types of initial differences that sets this amp apart from typical Marshalls, but when you examine the PC board you can tell the excellence in manufacture they put into this amp. Everything is laid out well, lead dress is even and the wave-soldered board leaves very little to complain about.

    The Power Transformer (PT) is the lay-down type with no wires exposed above the chassis, making for a much cleaner looking layout. Here is a photo of the underside of the PT:

    [​IMG]

    Here is another shot from the top, you can see how clean the chassis looks with the PT mounted this way, the black of the chassis in contrast to the PT looks pretty nice...

    [​IMG]

    The Output Transformer (OT) is mounted near the center of the chassis toward the rear edge near the back of the amp. This makes the amp very heavy on one side, as the PT seems oversized for an amp of this scale, and center-mounting the OT adds to the lopsided weight distribution of this amp. Don't get me wrong, it is much lighter than carrying a 100W giant... Here is a shot of the OT and the markings on top:

    [​IMG]

    If there was any aspect I would change on this amp it would be to add a choke and possibly swap out the OT for a ClassicTone version that has the 4-ohm output...

    On to the tubes next!
     
  4. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    The tubes shipped with the Haze 15 are Marshall-branded, the preamp tubes are red-labeled low-microphony JJ's (00063), and the 6V6GT's are white-labeled Shugyangs (00038). They have performed flawlessly since I got the amp a couple years ago new, it was a shame to box them up as spares...

    Here are a few shots of the tubes as shipped:

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    There seems to be a bit of confusion as far as biasing this amp is concerned, and I tend to err on the conservative side. As measured, the B+ voltage was 356 VDC, and the ma measured on each tube as far as bias was concerned was 14,x on one side, and 16.x on the other. The adjusting pots were sealed, and I am going to assume Marshall set these at the factory to be in the 15ma range (15mv measured at the bias test point).

    This is where the confusion starts to set in. The Weber bias calculator states that for my voltage they should be set at between 24-28ma. SteveD at Marshall states in this post that Marshall Service recommends 29ma: http://*****************.com/viewtopic.php?f=53&t=7413

    Now this must be calculating the 6V6GT as a 12-14 watt tube. The Haze 15 is NOT a 30W amp, it is being run very conservatively at 15W from BOTH tubes, so we obviously need to calculate for about 7W dissipation. This will put the bias at right around 15ma, very close to the factory setting. The Weber bias calculator confirms about 5W per tube at this setting. Weber Bias Calculator

    The trimpots for setting the bias have a very wide range, I could set the bias for just about any tube between 5ma and 50ma easily. Cranking the bias up a bit (just under 30) it was obvious that the tubes were working a bit harder. Clean headroom was reduced and it got gritty pretty quickly on the Normal channel, and I couldn't crank it on the Overdrive channel to test the bias there (wife and dog at home...).

    Next: Tung-Sols and NOS go for a ride...
     
  5. Dogs of Doom

    Dogs of Doom >>> Moderator <<< Staff Member

    Joined:
    Aug 2, 2012
    Messages:
    26,055
    Likes Received:
    33,992
    Location:
    Los Angeles
    Too bad the roadhouse is banned from typing...

     
    The Ozzk and Micky like this.
  6. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    But this seems to be erroneous.
    I can't seem to get a clear answer from anyone about this, even though the amp came set from the factory clearly about 1/2 of that number. I guess biasing for output dissipation would significantly lower the published number, as the amp is obviously not a 30W amp, and each tube can deliver about 12-15W in A/B configuration.

    When I saw that post, I just HAD to dig deeper...

    This seems to be a more accurate representation of how the amp came from the factory. But it still makes me question both James and Steve when they quote different factory specs that what the amp shipped with.

    But that brings up another point - Can we set approximate output wattage (dissipation) via the bias setting? Example - higher bias = more watts output?
     
    Dogs of Doom likes this.
  7. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    As promised, here is the retube info from last night.

    I pulled all the Marshall-branded tubes and placed them in individual boxes to keep them all together and safe. The red-label JJ's are apparently the preferred low-microphony version custom made for Marshall. These are preferred for combos because of the vibrations they are subject to.

    The Shugyangs in the power section weren't anything special, although they sounded great and presented no problems whatsoever. The OEM tubes should make for a great spare set.

    The tubes I installed were the result of some brief rolling, I ended up with a NOS RCA long-plate with a slant getter in V1, and a JAN / Phillips 12AT7 in V2. The PI slot got a Current Production (CP) Sovtek russian tube and for finals I went with a new set of CP Tung-Sols. Here is the data sheet for the Tung-Sols:

    http://www.tungsol.com/tungsol/specs/6v6gt-tung-sol.pdf

    Here is a photo and a link to the Tung-Sol page:

    [​IMG]

    Tung-Sol.com:: 6V6GT Vacuum Tube page

    These Tung-Sol 6V6GT's run about $25 each, and in comparison, the Marshall-branded tubes are about twice as much if you had to purchase them. You don't need to have matched tubes for this amp, even tubes from different manufacturers can be biased properly because of the separate bias adjustment controls.

    Once installed and biased to around 15ma each, the amp was dead quiet, no hum or noise at all. In the next few days I will get the chance to crank it thru the full stack it sits upon, even though this is a 15W amp, it is incredibly loud thru the Eminence loaded cabs it is connected to.

    Next I will touch upon some planned modifications...
     
  8. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    The Haze40 is also a beast, kind of a little brother to the DSL40c. The Haze40 has less gain, and suffers from some rattles and vibrations. I believe that is one of the reasons they discontinued the model line so quickly. Anyway, there are quite a few mods that apply to the 40, and as that amp is a 2X EL34 amp there is quite a bit of interest as well as knowledge that can be applied to this model. The Haze 15 benefits from this because they are similar in construction, and use only a slightly different layout.

    Also, because this design is similar to some of the DSL line (such as the DSL 15 and DSL 40c) we can take a few pointers and apply them here. Now don't get me wrong, I am not trying to turn this Haze 15 into a DSL, nor am I trying to mod it into a 800 or Plexi. I am trying to turn this into a little bit more versatile and much more dependable 'players' amp, one that someone could use for a variety of different types of music and could play for hours daily and still be reliable and predictable. (not that it isn't already reliable...)

    First I am gonna look at the big iron in the little beast. Mercury Magnetics makes a 'drop-in' upgrade PT for this amp, #MAR-HAZE-15-P/DUAL as well as a replacement OT with a 4-ohm tap #MAR-HAZE-15-O. Both of these transformers are $185 each, plus shipping. Just replacing these two alone bring the cost of upgrades to almost the price of the amp new, certainly over the cost of one used. BUT - The MM PT has a dual voltage input, which can be set for almost anywhere between 100VAC to 240VAC. This makes this a great little international amp... They also manufacture a few different chokes that would fit into this little beast, you can always email them for more information. Their MAR 100C 3H choke has been used in the past by other Haze 15 owners with good results.

    I am still waiting to hear from ClassicTone about options for this amp, I hope to have part numbers soon for any offerings they might have. Their 3H choke # 40-18058 would be a direct replacement for the 5W R34 resistor. It is the same choke for the DSL40c, and not too expensive, especially in comparison to anything from Mercury Magnetics. It is the damned shipping that gets things into the next higher price range... Anyway, this is the first bit of iron I will be adding to this amp, besides evening the weight distribution out it will tighten up the tone as I crank it up. One thing for sure, this being a lower wattage amp, you get plenty of chances to turn it up in comparison to a 100W monster.

    Another mod for the Haze40 that is not needed here on the 15 is changing the NFB resistor, R48. In the Haze 15 it is 100K which is perfect for this class of amp. Another change many users perform on Marshall amps is modifying the 'bright cap'. In the Haze 15 this is C58, which is 47pf as installed. This is a capacitor across the wiper of the Overdrive Gain control (VR2) and acts as a filter for the first gain stage of the Overdrive channel. The Normal (Clean) Channel never sees this control as V1B is bypassed in that channel. There is also a bit of talk about swapping out C59, which is installed in the Overdrive Master Volume part of the circuit after the tone controls. I am still not convinced on this mod yet, lets see how the others shape up before tackling this one.

    There are also mods for the treble-peaking circuits for the second and third gain stages, centering on R84 and R60, changing or adding a 470pf cap to these resistors. Also gonna wait on these until I get the need and a lot more ambition...

    A mention of the V1a cathode resistor has passed thru a couple forums, changing R15 to 2.7K and changing C12 to .68uf. Right now it looks like those may be the major mods users have tackled, I will do my best to seek out new mods, and list them here...
     
    ibmorjamn likes this.
  9. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    Well I heard back from AmpPartsDirect, which is a retailer for ClassicTone components.
    Rick Gessner is the Tech Support Specialist there, and is a veritable wealth of information.

    For the Haze15, there is no ClassicTone PT upgrade due to the LV (lo-Voltage) windings present in the OEM xfmr. No real need anyway, unless one wanted to convert the amp to a 240VAC model, and there you have 2 choices for the amp; the 240V Euro replacement from Marshall, manufactured by Arco Electric, #C1353PTNAE. (the 110/120/130V replacement is Arco Electric #C1353PTNAF)

    The choke recommended for use in the Haze15 is ClassicTone #18040. This is a 4H 50ma choke with a DC Resistance (DCR) of 150 ohms. Hammond also makes replacement chokes, but they are a more modern design using current materials and construction. They make several models appropriate for this amp, but I am finding they are all more expensive and more expensive to ship as well.

    I will have one on order soon, and it looks like installation will be a breeze. Apparently there is a spot destined for the choke already prepared, with a link soldered in place and two spade lugs ready to accept the wires. Plug it in, snip the link... See the photo below:

    [​IMG]

    Hardest part of the whole deal will be mounting the choke somewhere... How this will affect the amp is yet to be determined, my guess is that it won't do much until the tubes start drawing a bit of current, and the amp is incredibly loud already once you get past 4-5 on the volume. Time will tell.

    Next - On to the Output Transformer...
     
  10. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    ClassicTone offers 2 Output Transformers for this amp: # 18087 or # 18090 .
    Here is the dilemma; How do I choose one over the other?

    As you can see from the links provided above, one is a classic, vintage-style OT constructed from quality components in the same style as vintage amps, while the other is an 'upgrade' type of OT constructed from quality, extra heavy-duty components. So I posed this question to Rick Gessner at AmpPartsDirect.com and he gave me this reply:

    "The 18087 is a 60’s style (interleaved) transformer that has superior bandwidth than the 50’s style 18090 (tweed era).
    You can pick the one you want depending on the tone you want… cleaner headroom (18087) or a little more raw (18090)"

    For me it is almost a no-brainer, as I have always been of the mindset that Marshall amps have too much gain, and in this case the Haze15 is a perfect example. The Haze15 is a 2-channel amp, with the Normal Channel being a classic Plexi-style channel and the 2nd Overdrive Channel a JCM-800 style channel, with a Master Volume (MV) as well as a Gain control. Both channels lack 'clean headroom' so the 18087 OT from ClassicTone would be my choice.

    In this case, the finish of the 18087 is also more in style with the Haze15 chassis, all black with a 2-bolt mounting bracket. Here is a photo of the 18087:

    [​IMG]

    This looks like a bigger, beefier OT to me, the actual dimensions are 3 1/8" tall with 3 1/8" mounting holes. It has enclosed windings, and just 'looks' like it belongs in the Haze15. Again, here is a link you can follow to look at more info:

    40-18087

    On the other hand, if you are after a more 'raw' type of tone and would like a more vintage-looking OT with less clean headroom, choose ClassicTone #18090 which you can have a closer look at here:

    Fender Tweed Deluxe Style, 20W Output 4/8/16 Ohms 40-18090

    and here:

    Fender Output Transformer, Tweed Deluxe Upgrade Style, 8K to 4/8/16 Ohms, 50246

    Both of these OT's have 4/8/16 ohm output taps, so if you really needed a 4-ohm output, here is your chance to install one. Having the option to install either is really kinda nice, as the original, while well-suited for this amp, lacks the 4-ohm option. Also the OEM OT looks a little small by comparison, we shall see as soon as my new one arrives! Here is a photo of the top of the OEM OT:

    [​IMG]

    More about the other mods available for this amp soon!
     
  11. Ken

    Ken Well-Known Member

    Joined:
    Feb 24, 2009
    Messages:
    9,944
    Likes Received:
    3,160
    Location:
    Arlington Heights, IL
    I've been interested in the Haze ever since I played one in a Sam Ash once. But I remember reading of some factory defects and other QC problems the led Marshall to discontinue the amp because the list price wasn't high enough to cover all the warranty claims.

    Can anyone comment on this?

    Ken
     
  12. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    After reading a bit, talking with a few folks and looking under the hood I think you are correct Ken.

    Apparently the first few that left the factory had QC problems in that some components were under-spec'd, some of which were the 1-ohm bias voltage shunt resistors. There may have been other components, but I have not discovered all of the suspect ones yet, and I won't comment here until I have some sort of proof.

    Also, your comment may be correct about the cost to warranty repair these amps, seems like it is much smarter to discontinue the line and develop a new line (DSL15) to take it's place.

    As far as I know, these were (the Haze series, that is) the only Marshall amps to be produced in India. My bet is that they could get the Vietnamese to do it better and cheaper...

    This is one reason I feel these amps are gonna skyrocket in value in the future, they are great-sounding and playing, and extremely rare because only a few were made and survived...
     
    Roadburn likes this.
  13. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    After a very short week some new iron arrived on Friday, and I am stoked to get it installed into the Haze 15! East coast shipping is very quick, and for $15 I got all 4 transformers shipped right to my door. Anything this heavy should have been twice that amount to ship...

    The choke for this amp is rather small, but then again, remember this is a 15W amp, and there is not a huge demand on anything installed into the chassis. There is plenty of room on top and a limited space below the chassis, so you need to choose very carefully where you mount the choke. For me, I chose a spot where I could mount it as well as route the wires without removing the mainboard. Here is a photo of the spot I chose and the mounting/wiring holes:

    [​IMG]

    You can also see the newly mounted OT... More about that in the next post.
    Here is a closeup:

    [​IMG]

    As you can see, the choke is part #40-8040. which is the same as for the DSL5c.
    The choke is all-enclosed, and being all silver is a nice contrast to the all-black chassis. There is no component to remove to install this choke, and the spade lugs are already conveniently mounted to the mainboard, almost like this was eliminated from the design at the last moment. At $17, it is an easy and inexpensive upgrade that is easily installed without soldering.

    Here is the point where the choke wires are installed, you must clip the link installed on the motherboard that connects the two points together and bypasses the choke installation:

    [​IMG]

    You can clearly see the spade lugs labeled W1 & W2, as well as the link you must snip after the choke is installed. Pretty easy installation if you ask me...

    Here is a shot of the completed installation. I put some heat-shrink over the soldered spade lug connectors to pretty up the installation a bit.

    [​IMG]

    More on how these sound after the upgrade OT installation...
     
  14. johnnyeggz

    johnnyeggz Well-Known Member

    Joined:
    Jan 15, 2008
    Messages:
    273
    Likes Received:
    254
    Location:
    NYC
    I bet that OT would work in my modded DSL15
     
  15. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    You should email Rick at AmpPartsDirect and ask him for his recommendations.
    The guy is an expert...

    And yes, it probably would.

    Next post is my Haze15 OT replacement. Haven't had any time until now to do the write-up.
     
    johnnyeggz likes this.
  16. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    So last weekend I modded my Haze15 pretty heavily, the choke was easy in comparison to the OT replacement.

    Anyway, ClassicTone # 18087 was my choice here, they have 2 to choose from as far as upgrades are concerned. Here is the email reply I got from Rick Gessner at AmpPartsDirect (ClassicTone retailer):

    "The 18087 is a 60’s style (interleaved) transformer that has superior bandwidth than the 50’s style 18090 (tweed era).
    You can pick the one you want depending on the tone you want… cleaner headroom (18087) or a little more raw (18090)"

    Since the Haze15 is a 2-channel amp, with no gain control on the Regular Channel (Plexi-style) I opted for more headroom since the Overdrive Channel has plenty of gain, and I know how to work the footswitch... 18087 it was.

    And what a beast this OT is! Here is a photo of the two transformers side by side:
    (upgrade OT on the left, OEM OT on the right)

    [​IMG]

    Here is another, it is hard to see the actual size difference unless you an see all angles...

    [​IMG]

    The removal process is fairly straightforward, all connections are insulated spade connectors, with the spade lugs mounted directly on the mainboard. Here is a photo of some of the output connectors on the speaker board:

    [​IMG]

    Here is the wiring for the output:
    The original OT has Yellow 16-ohm=W301, Red 8-ohm=W302 and Black common=W303
    The upgrade OT has Brown 16-ohm=W301, Green 8-ohm=W302 and Black common=W303

    The input wiring is as follows:
    The original OT has Blue=W10, White=W11 and Brown=W12
    The upgrade OT has Brown=W10, Red=W11 (center tap) and Blue=W12

    All I has was some odd colored heat-shrink, but the wire colors are obvious:

    [​IMG]

    The OT input connections are near the top-right corner of the photo.

    The upgrade OT mounts directly in two of the 4 original OEM OT mounting holes, but lacks a rubber grommet on the other side of the xfmr. I ran all wires thru the original grommetted hole, and the wires were plenty long enough.

    Here is a shot of the finished installation, the all-black OT compliments the black powder-coated chassis nicely, probably one of the nicest looking chassis I have ever seen (if I do say so myself...).

    [​IMG]

    How it sounds will come later, I haven't had a lot of time as of late. We will see...
     
  17. johnnyeggz

    johnnyeggz Well-Known Member

    Joined:
    Jan 15, 2008
    Messages:
    273
    Likes Received:
    254
    Location:
    NYC
    I remember reading someplace that the Haze and DSL are using the same OT,but I'll give AmpParts a buzz.
     
  18. Micky

    Micky Well-Known Member VIP Member

    Joined:
    Apr 29, 2010
    Messages:
    21,154
    Likes Received:
    17,901
    Location:
    Vermont
    I think the Haze15 got discontinued and the DSL15 may have been designed in a similar fashion to take it's place.

    From what I understand, early Haze amps had their share of problems, and Marshall may have decided that it was too expensive to continue to produce them especially if they had to repair them under warranty.

    While I don't have a DSL15 to experiment with (would love to have someone send me their broken one...) it appears as though the DSL15 is a simpler design without any effects like the Haze15 had built-in. If I had more time to study the design I could pick each one apart, but the basic similarities are all there.

    The DSL15 actually has more design similarities to its big brother the DSL40c except for the power section. As far as the OT is concerned, apparently there are plenty of 15W or so push-pull designs available, I chose ClassicTone based on brand loyalty. Also I refuse to pay the inflated MM price...
     
    johnnyeggz likes this.
  19. johnnyeggz

    johnnyeggz Well-Known Member

    Joined:
    Jan 15, 2008
    Messages:
    273
    Likes Received:
    254
    Location:
    NYC
    I'm definitely gonna get one.
    Although my DSL 15 sounds great after the mods, the low end still sorta falls apart at gig volumes.
    I'm thinking the higher headroom / more substantial ClassicTone OT would straighten it out.
     
  20. evh

    evh New Member

    Joined:
    Nov 29, 2014
    Messages:
    33
    Likes Received:
    11
    Location:
    Northumberland,UK
    some great info here hope some of it works with the haze 40
     
    Micky likes this.

Share This Page