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Pulse amplifiers from MCM Electronics - cheap tube amps and cabs

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

  1. Fulco

    Fulco TDPRI Member

    Age:
    57
    5
    Oct 4, 2016
    LA
    Hey, hey, Radu7... I'm really considering the matching white cab. I may get it and change out the speakers to Celestion Vintage 30's if I'm not thrilled with the overall tonality. Not sure just yet. I'm also thinking the V30's may give me a few more decibels and offer a fatter, punchier, and tighter kick. This little amp is certainly worth the money! Good luck with the new one, I'm sure you'll dig it!
    Peace
     

  2. Fulco

    Fulco TDPRI Member

    Age:
    57
    5
    Oct 4, 2016
    LA

    UPDATE:
    I just returned the Pulse 60. I decided to just stop working! Only one tube glowing and the other nothing! I've decided on a refund and to move on. Oh well!
     
    Last edited: Oct 25, 2016

  3. richey88

    richey88 Friend of Leo's

    Jul 28, 2009
    philly suburbs
    This piques my interest
     

  4. richey88

    richey88 Friend of Leo's

    Jul 28, 2009
    philly suburbs
    If it has a 16 ohm speaker out, I'm down!!
     

  5. radu7

    radu7 TDPRI Member

    4
    Oct 16, 2016
    Alabama
    Major bummer! So we're up to three of the 60 watters not passing muster. I wonder how many were sold in total? To add to this, I finally got my replacement Pulse 60W (exchange for the first one where the effect footswitch did not work and the right power tube kept red plating). Unboxed it, plugged it in, same thing happened... Two in a row that plugging a footswitch into the switch jack for the built-in effects and pressing it does not function (and I have tried multiple footswitches). Red LED on the switch barely glows when the footswitch is depressed, but no amount of pressing it ever shuts off the reverb, chorus, flanger, or whatever effect you happen to have selected. Only difference between the replacement head and the original I received is that on the replacement the left power tube is the one that likes to red plate. Oh and the 'Pulse' label on front of the head on the replacement was glued on crooked this time. :)

    I spoke with MCM customer service (they are great, by the way.) and they put me through to their tech support and they are going to look into the whole footswitch thing since this is two in a row where the footswitch was a no-go so this could be an issue on this particular batch. It's really not a deal breaker, but the red plating tube is. If it craps out just as the warranty expires you're left with a nice 'project box' for your own DIY tube amp, I guess, but knowing MCM they'd probably still take care of you. I took a quick look at the guts of the first one I got before I sent it back and the soldering, etc... looked quite good, and not at all shabby, about as good as I've seen anywhere. Looks like it would be a hassle to set the bias in it when the time came to do that, which unfortunately might be as soon as you get one it seems, and there are no schematics for it or technical docs for it to be had that I'm aware of. I did see a small black pot with '42V' printed on the PBC next to it on the main board, but getting at that pot would require an almost complete teardown of it. I'm mulling over whether I want to try a third one or not. And if not, I may send the white 2x12 cab back as well. Though the cab was cheap enough and sounds decent enough to keep.
     

  6. radu7

    radu7 TDPRI Member

    4
    Oct 16, 2016
    Alabama
    It does. 4/8/16 ohm outputs on the back of the head.
     

  7. spl3444

    spl3444 NEW MEMBER!

    Age:
    54
    1
    Dec 15, 2016
    NJ
    Just picked up the 15W. 2 - 6V6 and 1 - 12AX7. After a very quick inspection there are several ICs in the head. It is some type of hybrid. Sounds good.
     

  8. Chris S.

    Chris S. Asst. Admin Staff Member Ad Free Member

    Age:
    114
    Mar 26, 2005
    Near TELE-Town (Wash. DC)
    Admin Post
    The presenter in the linked video says very clearly,

    "These are all solid state amps." CS
     

  9. archetype

    archetype More tone than talent Ad Free + Supporter

    583
    Jun 4, 2005
    Williamsville NY

  10. Paul in Colorado

    Paul in Colorado Doctor of Teleocity Ad Free Member

    Mar 17, 2003
    Fort Collins, CO
    Chris, the COMBO's are all solid state. That's what he's showing when he says that. The heads are tube (or hybrid).
     

  11. Chris S.

    Chris S. Asst. Admin Staff Member Ad Free Member

    Age:
    114
    Mar 26, 2005
    Near TELE-Town (Wash. DC)
    Admin Post
    My mistake. Thanks. CS
     

  12. Zipslack

    Zipslack Tele-Meister

    216
    Jun 8, 2011
    Mississippi
    Fender SuperChamp XD and X2 are hybrid (SS preamp, 12ax7 pre/phase-split, 2-6v6 power)...don't see a lot of grief about them. Looks like it may be about in the same vein. The 15W doesn't have reverb or effects, so it probably isn't even DSP - just plain old op-amp and/or BJT circuitry for the pre-amp.
     

  13. Fulco

    Fulco TDPRI Member

    Age:
    57
    5
    Oct 4, 2016
    LA
    I had the same issue with the pedal. You have to use the ones they sell for that model... They actually sell 2. One for channel, one for reverb.
     

  14. Scooby9261

    Scooby9261 TDPRI Member

    Age:
    38
    8
    Mar 10, 2017
    connecticut
    Anyone have any info of any Mod's ? Or the schematic ? Want to mess with this thang ;-)
     

  15. Scooby9261

    Scooby9261 TDPRI Member

    Age:
    38
    8
    Mar 10, 2017
    connecticut

    The clean channel isnt as open as Id like it to be, I changed the tubes to JJ's and it helped but Im after trying to get more of a Fender tone out of it. Im sure there could be a few quick ways to get the amp to open up and not be so dark.
     

  16. Scooby9261

    Scooby9261 TDPRI Member

    Age:
    38
    8
    Mar 10, 2017
    connecticut
    Tone stack ? Thats what my first thing to try.
     

  17. DeanEVO_Dude

    DeanEVO_Dude TDPRI Member

    12
    Aug 17, 2010
    Colorado Springs, CO
    I'm really interested in the 15H or the 30H. I've been looking for an amp with 2 channels, foot switchable, with effects loop. I want reverb also, but not a deal breaker with the effects loop. This seems just right enough. Are there any more updates on these amps?
     

  18. gmdattilo

    gmdattilo TDPRI Member

    Age:
    39
    3
    Oct 5, 2017
    Kentucky USA
    I know this is an old thread but maybe someone is still interested in these amps. I bought a 30W head a few weeks ago. I wasted no time tearing it down to see what is inside. Yesterday evening I spent some time working up a schematic for the power amp / power supply board. Its a pretty typical circuit. The ECC83 is a long tail pair phase splitter. The 6L6WGB power tubes are in the typical push-pull configuration. Plate voltages measures about 375V when the amp is warm. That leads me to the major short coming in this amp (or short comings). The bias circuit has very little range. So little that my amp was delivered with the bias pot at the coldest possible position and one of the poorly matched 6L6's was over 70% dissipation at idle. Its my understanding that 70% is considered the max bias for a class AB circuit. This may well be the reason that there were complaints of red-plating in some of the earlier posts. I added 1 resistor to the bias circuit and I was able to get both 6L6's under 70% at idle. They are still mismatched by about 9mA . Obviously there was no matching at the factory. The schematic came in handy for this. Right now is just chicken scratch in a notebook. If anyone is interested I'd be happy to share once I've cleaned it up. I have no intention of reverse engineering the pre-amp. Its all surface mount op-amps and passives. Not worth putting the time into it. I bought this head with the intention of building a tube pre-amp anyway.

    I hope someone will find this info useful.
     

  19. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    That's because the reviews are not overwhelmingly positive - even from those who like it. And those are players who obviously are not very experienced.

    Also because if you read carefully - these are hybrid amps, not all-tube designs Read on:

    The very first review for the 15-watt head read:

    "...the tone section doesn't have too much effect on the sound. Also, it's not very loud and I had a bad hum problem that I did not experience with another amp in the same area as this one."

    One 2 reviews later commented:

    "It doesn't sound 15 watts, maybe 4 or 5..."

    the next one:

    "This amp has only one 12AX7, and you can't overdrive it without a pedal."

    Next:

    "The tone stack is rather odd in that it is very subtle, and even extreme changes were barely noticeable."

    A 15 watt tube head that can't be pushed into overdrive? ONE 12AX7? How do they do that? There's a preamp tube and a driv...errrr, wait!

    With only one preamp tube and two power tubes there has to be a hybrid part of the design - and it sounds like it's the preamp, with the 12AX7 being a driver tube.

    Based on those quotes from consecutive reviews and the fact it's a hybrid it doesn't sound like they are much of a bargain at all - just cheap "half solid state" amps from a manufacturer trying to cash in on the tube market.

    I wholeheartedly recommend NOT buying one.

    Fulco - Unless I miss my guess you will get an amp with a digital preamp/effects (VERY cheap to make), a 12AX7 only used as a driver and 2x6L6's in a non-adjustable fixed bias circuit. The tubes will be Chinese and mounted on the circuit board, not on sockets on the chassis.

    The only "overdrive" you will get out of it will be digitally created. You may get it to distort, but that may be a questionable tone as well.

    I have to ask - why spend the money on a cheap digital/tube hybrid amp like this instead of saving the money towards a real tube amp? I just don't understand the logic. I'm not saying you're wrong - but I don't understand the "why". Especially when you only "believe" there's no restocking fee instead of having verified it!
     
    Last edited: Oct 5, 2017

  20. gmdattilo

    gmdattilo TDPRI Member

    Age:
    39
    3
    Oct 5, 2017
    Kentucky USA
    i can only speak first hand to the 30W version...

    id say this head is every bit of the 25-30 watts. Its a good deal louder than my 15w super champ X2 . That super champ also has an entirely solid state pre-amp and (not also) a DSP for effects. The 30w and the 15w versions of the "Pulse" have no DSP. There is nothing digital in there whatsoever. They are flush with op-amps but those are just as happy to "overdrive" as a tube. The 30w version has a spring reverb tank. Its tiny and cheap and it sounds tinny, but it is true analog. I believe that the 60w head does have a DSP. It probably gets mixed in that same circuit that the 30w uses for the reverb. There are many indications on the PCB that they use the same amp / power supply PCB in all 3 versions. The same is probably true of the pre-amp PCB.

    now I'm gonna stick up for the printed circuit board in these amps... There will never be a point-to-point wired circuit that can hold a candle to a well laid PCB, period. Aiken Amps will tell you the same. If you have a high volume design and a decent tech to lay it out, a PCB is the only way to go. I make no claims that this PCB is well laid but it is quiet so I'd say they did not do a bad job.

    The bias is not fixed. There is a common bias adjust for both power tubes. Mine required some modification to have usable range but there is provision for adjustment. I'll probably modify mine further to have separate bias pots for each power tube.

    If you're inclined to do some hacks and mods this is not a bad buy. I enjoy understanding the nuts and bolts of an amp just as much as i enjoy playing (granted poorly) through it.
     

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