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

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

  1. jackpine123

    jackpine123 New Member

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    Hey Micky, love the great, fantastic info. I've been using my Haze 15 playing gigs
    for about a year or so. I have no problems on stage with loud drums and a loud bass player. I do put a mike on the amp for the main PA. I am older, so I really like the
    lightness and portability. No more hauling big amps for this buckaroo. I am still confused at where to bias this head. Is it 14 15 mV? Jon from the Tubesore says, with a plate voltage of 365V bias is from 19mA to 27mA. Help......Thanks for any info.
    Stan
     
  2. Micky

    Micky Well-Known Member VIP Member

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    Hi Stan, thanks for the kudos... But I am not the only one who has dug deep into this amp. I am only 1 of many...

    I see you have stumbled upon my dilemma. Theoretically, according to my Engineering background the bias should be set near 15 ma or so. BUT higher values may yield different results. SO, depending on your needs, the bias should be set according to the tone you desire. Colder bias (10-19ma) may yield cleaner cleans, and possibly not as much crunch, even possibly thin or fizzy tone on the OD Channel.

    Higher bias (20-25ma) may mean less clean headroom and possibly flubby or undefined OD channel stuff. According to the math, 14ma bias should result in about 7.5 watts output per tube. I think in this case more users need to chime in here in order to see a lot of different results and opinions.

    My thoughts on bias differ from many others, in that I feel that the tubes on either side of the A/B final section should be BALANCED, not necessarily set to an exact, specific, predefined value. Many refer to this type of biasing is the 'crosstalk' method, but I stray from the exact method used to perform this.

    Sorry for the psychobabble, but after digging deep into this head it has made me re-think a lot of my methodology, even though it is a rather simple amp with typical PCB construction. I do know I love mine, it is light, powerful and sounds great. I do have to admit I don't play mine a lot lately, I am stuck on the DSL5c in the living room where it is nice and warm in the winter!

    If you are gonna re-bias yours, it is important to measure where it was set, and then try different settings. You might end up setting it back where it was...

    OH - Many new members put a post in the Introduce Yourself section where they can tell everyone a little about themselves. I am certain that many here will welcome you, especially if you post photos of your equipment!
     
  3. jack daniels

    jack daniels Well-Known Member

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    Hey Mickey, very nice pics and breakdown of the Haze 15. FWIW, years ago I used to have an account with International Components Corporation (ICC) and I used to get the dark blue coated 6V6's with the clear domes. ICC stamped them Russia as country of origin, and they were great sounding tubes and seemed to handle the higher B+ voltages that my BFDR put out w/GZ34. I can understand hanging on to these tubes for posterity. I was really interested in your experience with the Classic Tone output transformers since they're cheaper than most current transformers and have paper bobbins ala transformers of old. I used to own a Fender 1x10" tweed Vibrolux amp that was so sweet and I really believe that the old paper bobbin OT in that amp is what made it so classic sounding (barring the Jensen Alnico speaker, and other components).
     
  4. stock_hippie

    stock_hippie Well-Known Member

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    OT: any idea why there aren't any JMP-1 around?..I see DSL-1 and JVM-1 and JCM-1 on ebay..never a JMP…thanks
     
  5. Micky

    Micky Well-Known Member VIP Member

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    Yes, ClassicTone stuff is great. I agree, the classic construction vs. modern construction is an advantage many here overlook. Oh well. It is too bad they don't make more PT's, but with all the different voltages needed these days, I can see where it is more difficult to manufacture.

    I am still searching for the ultimate 6V6, I can use them in my Princeton Reverb as well as the MHZ15. I like the Tung-Sols, as well as the OEM Marshalls a lot. Have yet to try some TAD's, but rolling the finals in these amps is not high on my list, as they are epic tone monsters just as they are. I would love to try some of the ones you described!

    Yeah, the pics are pretty good, I am kinda ashamed to admit that I use my wife's point and shoot Nikon for the close-ups, even though I own tens of thousands of dollars worth of hi-end pro stuff with extension tubes for macro work...
     
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  6. jack daniels

    jack daniels Well-Known Member

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    I currently have Tung Sol 6V6's in my 66' Fender BFDR w/JJ GZ34 that sound great. If I were to be able to afford the good stuff I'd go w/NOS 6V6 like these...

    https://tubedepot.com/products/6v6gt-jan-philips

    OR

    https://tubedepot.com/products/bendix-5992-6v6gt
     
  7. jack daniels

    jack daniels Well-Known Member

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    There was a OT transformer shootout on the web, and the Classic Tone, Heyboer, MM and Weber were compared. I believe people mostly preferred the paper bobbin Classic Tone transformers.

    http://www.classictone.net/PaperVsPlastic.html
     
  8. Bluesdude123

    Bluesdude123 New Member

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    Hey!! Any update on sonic improvement since the output transformer replacement and addition of the choke? I just got a Haze 15 and replaced the 6V6s with new Tungsols and the ECC83s with NOS GE 12AX7s in V1 and V3 and a new Tungsol 12AX7 in V2. I also clipped one leg of C59. I find the OD channel useable now, but can't really find treble unity between the clean channel and the OD channel. With the bright switch on and treble at about 12 o'clock, the OD channel sounds great, but when switching to the clean channel it is way too bright. I played a gig last night with the Haze 15 and a semi open backed 4x12 cab with heritage G12Ms. Had moments of amazing tone, but it was a battle. Seemed like either a wicked clean sound or wicked OD sound, just not a smooth transition between the two. Hopefully with some more time using the Haze, I will be able to smooth that out. Contemplating just running the clean channel with a Bluesbreaker clone and a tube screamer and not using the OD channel when playing live. That would be a total shame though, because both channels can sound great when using the eq individually, just seems impossible to switch between the the two without some drastic eq adjustments (even with clipping C59). Anyway, just my initial impression of the amp, but I'm really curious to hear how your amp is sounding Micky! Please let us know!
     
  9. Swede

    Swede Well-Known Member

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    Would love to hear how this little beauty sounds:)...Awesome write up
     
  10. stacker22

    stacker22 Member

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    Could not have said it any better
     
  11. MilesTeg

    MilesTeg New Member

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    I stumbled across this post when looking for info on setting the bias on my Haze 15 head. I purchased the amp used but it does not look like the loctite has been broken on the bias pots. My current measured bias is 29 mV on one tube and 26 mV on the other. From this post it seems people think the range should be more around 15. I contacted Marshall directly and they responded it should be 29 mV per tube.

    Not sure what to think...
     
  12. jimmyjames

    jimmyjames Well-Known Member

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    Meet in the middle? Try 22 and let your ears decide. My DSL15H likes 21 :yesway:
     
  13. renips

    renips Well-Known Member

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    Awesome tutorial!!!. I have owned the HAZE 40C since 2010. I had some issues in the beginning but those have been taken care of long ago. The amp sounds awesome. It has plenty of power. I changed out the stock speaker for a vintage 30. I love the clean channel on the amp. The onboard effects are a nice touch but I do not really use them. I also like the design of the front with the control knobs on the top. Very classic look. Made in India. May have deterred some people but it is a very solid build.
     
  14. bzrkrage

    bzrkrage New Member

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    Hey all, first time poster, first time Marshall buyer.
    Just searching like Miles to find how to bias, mine was a virgin in the trim pot.
    One was 16mA, other 27mA. Went with 27 equally across the board.
    New 6V6 GT-R & NOS Continental 12AX7's

    There you go.
    Also just put in the Hammond 4H choke. Less noise.:applause:
     
  15. bzrkrage

    bzrkrage New Member

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    Here is a photo with 112 WGS 12/C 16ohmn
     

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  16. temporarychicken

    temporarychicken Active Member

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  17. Believer

    Believer New Member

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    I picked up a MHZ15h NOS b-stock and have been looking for info on it. This is great--I have a matched set of Electro-Harmonix 6V6GTs ready to install. I will probably do the choke mod as well. Cool little amp. Thanks for the great thread.
     
  18. jamesm

    jamesm Active Member

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    Thanks for this article Micky. I still have a bit of a soft spot for the 15.
     
  19. jamesm

    jamesm Active Member

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    Here's an extra few tidbits.

    As Micky pointed out, there are 4mm spade terminals exactly where you would put a choke. They were there because the board was a development of the 40 and were where the standby switch was on the bigger amp. I left the parts there as there was nothing to be gained by removing them and so that a standby switch could be incorporated at a later date if desired (maybe for a 40/50W version).

    As regards the outputs being octal, there were two reasons I went for 6V6. Firstly, I love EL84s in simple amps like the 1974 and the AC30. I have never got on with them in any amp with negative feedback and a more complicated preamp. Secondly, I had the thought of future developments, and a larger amp in head format was one possible addition to the range. The PCB was designed to take the higher voltages and currents required to make 50W.

    As regards replacement transformers, I was surprised to see that you can get upgrades! There is one transformer change that I like a lot, which is a slightly higher HT voltage. I have used one with more HT making 20watts and it has a more bitey sound. It is akin to the differences between EL34 and 5881 Marshalls. If I were offering alternative transformers, I would go this route. Obviously I don't recommend that anyone changes any transformers for any reason...
     
  20. uriy

    uriy New Member

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    Hi ! .. no one knows what the number 3 on top of the resistor means? in front of the cathode repeater on the grid of the second lamp / did not find any references to such a designation in the circuit / can a selection of a resistor? .. then usually an asterisk
     

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