Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

Pulse amplifiers from MCM Electronics - cheap tube amps and cabs

Discussion in 'Amp Central Station' started by Ringo, Jun 30, 2016.

  1. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    You can't "mod" one of these and "change" it to a normal tube amp - you'll need to punch it for two actual preamp tube sockets AND install the sockets, replace the power transformer with one that can handle the additional filament current load (and whatever else), modify the power supply filtering to handle the additional tubes, replace the entire PCB with a circuit board usable for a full tube guitar amp, work out all the required lead dress and ground schemes...by the time all that is done you might as well buy a REAL tube amp for less than your total investment in one of these things.

    These are not normal tube amps that you can "mod" or adapt to other circuits. They are digital amps with a tube power section *only*. That is not something you can "mod in the ways being discussed. And based on the failure rates, do you *really* want to use ANY of the existing parts?

    Why stick up for printed circuit boards you can't use for anything else?

    What a waste of money IMO.
     

  2. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    That has nothing to do with it. Fixed bias amps (which does NOT mean "non-adjustable") with adjustable bias normally have one bias pot. Some have to be adjusted by replacing the bias resistor.

    Sounds like you don't know the difference between "fixed" and "cathode" tube biasing. You will not be able to add a tube preamp without changing the power transformer and revamping power supply filtering.

    Please see my post above.
     

  3. radiocaster

    radiocaster Friend of Leo's

    Aug 18, 2015
    europe
    The transformer might be able to handle it, but all that work means it might be easier to build an amp from scratch.

    This looks pretty cool though:
    http://www.gear4music.com/Guitar-and-Bass/SubZero-Tube-H50R-50W-Valve-Guitar-Amp-Head/MHI#full-des
    made by Belcat from what I've heard, 50s Bassman copy with master volume and spring reverb. There is no voltage switch for US either, so the transformer would need to be rewired or replaced, if you want to use it with 120V AC.
     

  4. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    In a cheap Chinese amp with a history of *not* working in stock form? Do you really think they over-engineered the power transformer to handle the additional current requirement of *more* tubes than stock? IMO "might" is probably stretching it - and good luck getting the precise transformer specs.
     

  5. gmdattilo

    gmdattilo TDPRI Member

    Age:
    39
    3
    Oct 5, 2017
    Kentucky USA
    those were your words...

    fixed biased, yes. poorly designed yes, but still adjustable.
     

  6. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    I haved no idea what you comment means. You didn't reference it to anything specific.

    If it had to do with your comment that "the bias is not fixed" - that is an incorrect statement statement. It is in fact "fixed" - but it is adjustable.

    There is a very specific technical difference between the terms. It's important to understand that and use the terms consistently so other readers are not confused. It sounded like you did not understand the difference and there is no previous tech info posted by you to assume otherwise.
     

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