First tube amp. Few questions

Discussion in 'Amp-a-ridifiers' started by HDCornerCarver, Aug 12, 2017.

  1. HDCornerCarver

    HDCornerCarver Squier Talker

    Age:
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    64
    Mar 18, 2017
    Lake George, NY
    Picked up my first tube amp yesterday. It's a Marshall Haze 40 I got for $200. It's a little abused, and the guy didn't sound like he's ever changed the tubes in it. I may have jumped a bit too soon at it, since I'm now reading they're pretty prone to failure. It sounds great though, and it's so much warmer than my solid state Fender. Only quirk I've noticed is the overdrive volume seems low without gain (unless that's normal, I'm still learning).

    So question is, should I do any maintenance to maybe fix any potential problems? Should I change and bias the tubes, and if so is it something I could tackle myself or should I have a tech do it? I'm a mechanic for a living, but I don't have much experience with electrical repairs, particularly audio. And finally is this something to address immediately or am I free to rock on for a few weeks? I'm just a bedroom musician so this thing would barely register on the volume dial.

    May check out a Marshall forum, but I figured you folks usual give sage advice. Thanks in advance for he help.

    Here's a few pics. I have to give it a good cleaning still

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  2. squierTony

    squierTony Squier-holic

    Jul 4, 2012
    seminole Oklahoma
    I think you should send me that cvc and that would fix everything.
     
  3. DaveDrums

    DaveDrums Squier-Nut

    605
    Feb 2, 2017
    MA, USA
    Not to be an alarmist but take it to a tech, don't reach in or touch anything if you're not familiar w/ working on amps. They hold voltage and can kill you.
     
  4. wickedtools

    wickedtools Squier-holic

    May 16, 2010
    west texas
    Yea take it to amp repair guy the Caps can be lethal ;)
     
  5. jackdragbean

    jackdragbean Squier-holic

    Nov 16, 2011
    Mississippi
    Rock it for a few weeks and then send it to a tech and have them go through it. Check everything. Tubes possibly still good. Nice amp. Congrats on the buy
     
  6. HDCornerCarver

    HDCornerCarver Squier Talker

    Age:
    26
    64
    Mar 18, 2017
    Lake George, NY
    Thanks for the advice. I'll play it for a bit and save up some loot to have a tech check it out.

    Afraid I'd be lost without it. She's a keeper for sure!
     
  7. platefire

    platefire Squier-Nut

    Age:
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    Sep 14, 2016
    North Louisiana
    Hello! I've had some experience with tube amp as I am a self taught DIY builder and with repair/maintenance.

    First, There is a ton of information about tube amps on the internet. So if your willing to do research, study your can learn. That's how I learned what I know.

    Now having tech experience, the first thing I would want to do would be to locate a schematic and layout drawing of the circuit that usually can be obtained for free on the internet.

    When I got the schematic and/or layout in hand I would want to pull the chassis, observe the circuit and check for any obvious burn marks on components. I would check the voltage at critical points of the circuit and compare those to the values on the schematic. I would also check the bias of the power tubes. So it should be pretty obvious to do all that, you need to know what your doing especially with the high DC voltage in an amp. A shock from those voltages could stop your heart! So to accomplish those thing just discussed you would need to learn amp safety along with the proper way to do each thing before just diving in. It's all on the net and lots of good books available.

    A couple of things I would recommend if you like the amp and want to keep it. I would buy a new set of tubes and keep the old ones as spares---since you don't have any tube inventory. Nothing like starting with a clean slate tube wise and then you'll know if it short of performance in any manner, it won't be the tubes. Then you will need to bias you new power tubes. You would need a tech to do that until you got up to speed on amp maintenance to do it yourself.

    On the problem you mentioned about low volume and no gain! Overdrive should have volume and gain---so I would agree a fault here---unless you haven't quite figured out the amp yet and not adjusting it right? Short of operator error, I would suspect a preamp tube. Best way to check it is to find out which preamp tube drives your OD and try a known good tube replacement to see if it makes a difference. You may need a schematic to find out which tube is associated with your OD. So check for a faulty tube first by trying a known good one---an good excuse for new set of tubes. Also if you knew what tube was associated with OD, you could try cleaning the tube socket with Deoxit Contact cleaner---sometime tube socket contacts get corroded.

    This should give you something to think about, rather you want to learn to be your own amp tech or rather you would rather pay a tech to do it for you. I would not recommend diving into the inners of your amp without a lot of pre-study to learn amp safety, general amp operating principles, learn to use a multi meter and soldering. Platefire
     
  8. Hard Road

    Hard Road Squier-Meister

    Age:
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    Apr 18, 2017
    Orange County
    I would think you need to use at least a little gain for the volume to be useful
     
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  9. HDCornerCarver

    HDCornerCarver Squier Talker

    Age:
    26
    64
    Mar 18, 2017
    Lake George, NY
    Thanks for the advice. I wouldn't mind learning to work on amps, but I'll skip it this time and send it to a tech. Hopefully doesn't run me more than the amp.
     
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  10. mikm

    mikm Dr. Squier

    Jun 4, 2012
    NY
    Best to get some use out of it at least for a couple of weeks! Make some stops at the local music shops and see if by chance they have a similar Marshall and someone with knowledge that can offer you some info etc! Sooner or later it would be a good idea to get it serviced etc. Nice find, good luck.
     
  11. Big tuna

    Big tuna Squier-holic

    May 6, 2014
    east Tn
    whole tube sets are not bad for that amp 79 and free shipping for jj's even there common tubes and lots around if and when you need them. Yours may be good for a long while yet. play it awhile and see . Enjoy the tubes man no more SS for you baby!
     
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  12. HDCornerCarver

    HDCornerCarver Squier Talker

    Age:
    26
    64
    Mar 18, 2017
    Lake George, NY
    Tech is getting it in a few weeks. $160 to install new tubes and set the bias so not as bad as I'd imagined. I'll ask to save the old tubes for spares and do more research so I can tackle the maintenance next time around.

    Thanks again for the advice!
     
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  13. Joe90

    Joe90 Squier-Meister

    481
    Jul 6, 2014
    Western Canada
    Congratulations on your first tuber!

    Welcome to the slippery slope... ;)
     
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  14. Ralph124C41

    Ralph124C41 Squier-holic

    Feb 10, 2016
    Years ago I had my Fender Custom Reverb (the model with 2x12 and no master volume control) fixed and had it retubed. It cost me more than I paid for the amp but really it was worth it. It's the best amp I've ever played through that didn't cost an arm and a leg and a kidney. The tech guy, who hand a shop in West Virginia and mainly just did amp work, put in a set of matched Grover tubes and rewired the amp and even gave me the old frayed wirng. Reminded me of getting your car fixed and the mechanic giving you the defunct parts.
     
  15. platefire

    platefire Squier-Nut

    Age:
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    Sep 14, 2016
    North Louisiana
    Well tube amps are still around after all these years because the tone is more organic than the sterile sound of solid state and the way tubes breathe with the dynamics of your pick attack. SS Amps have improved over the years because designers have built SS circuits to mimic tube amps. Even after all that tube amps show no sign of releasing their lead in the market. So now you understand now that you've been bit by the tube bug. Platefire

    BTW----That's why they are worth the extra maintenance!
     
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  16. jskeen

    jskeen Squier-holic

    Feb 9, 2016
    Texas
    a little extra info for you on your haze 40. it is in fact a Marshall amp, it was designed in-house by one of their engineers specifically to be produced in India and hit a given pricepoint. It was not based on an existing circuit, and as such, doesn't really sound a lot like one of the "classic" Marshall products. It actually works quite nicely as a clean amp and takes pedals well, but the built in overdrive channel is pretty universally disliked.
    The bias on the haze 40 is super simple and unlike any other Marshall design. there are separate adjustments for each tube and a dedicated 3 pin connector to measure the results.

    As long as you are not expecting to get that super thick, meaty, Marshall overdrive out of it, it's a really nice sounding amp, works well at reasonably low volume and is a lot easier to set up and get a good tone out of than most marshalls.
     
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  17. platefire

    platefire Squier-Nut

    Age:
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    Sep 14, 2016
    North Louisiana
    Just a little History! The first Marshalls where a direct duplicate of the 5F6a Bassman circuit. From there they began to modify that original circuit to add different cathode bypass caps and resistors, adding preamp gain stage to add gain in the overdrive channel until they arrived at the famous Plexi. Then Pete T of the Who needed more volume because he could not hear his amp over the roaring crowd. So then enter in the 100 Watt Marshall Stack. I guess then after that and all the following Marshall models including yours, is History.

    One more thing! Part of the charm of the Marshall Bottom End Thump was the guys in the late60's/70's turning up the volume on the early non-Master volume amps and pushing the power tubes into saturation. These days that kind of volume is not as popular as then---so there is an up surge of smaller watt amps these days that can be driven into power tube saturation without blowing the walls out. That's why I like my DIY Champ a lot:>) Platefire
     
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