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Thread: Mercury Magnetics Valve Junior

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    Mercury Magnetics Valve Junior

    A friend sent me a project a few weeks ago that he had inherited, so I finished it. It is a Epi Valve Jr head, and a MM upgrade kit. It has beefier transformers, (of course), and a choke, and a few circuit mods, including adding a 6V6 power tube.
    After I assembled it, I plugged it into a K130 cab for testing, waaay to bright. I remembered I had a Peavey cab with a Sheffield 12 in it, and that did tame some of the highs. I used my Tele, with Texas Special pickups, but anything past 1/3 volume, started breaking up. At 1/2 volume, very nice sustain/overdrive, and 3/4 volume will runaway into feedback, if you let it! I took it down to what passes for a music store in my little town, to let the R&R guitars play with it, its too gainy for me!
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    The upgrade kit must have cost more than the original head. It looks like the EL84 and 6V6 are in parallel and there's a bright circuit (R and C in series) across the 1M resistor feeding the vol pot.

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    From what I have seen The amp head was around $150, and the MM upgrade kit was $300!
    I debated tweaking it, (maybe adding a switch to bypass the "bright" add on, and even a switch to put the 6V6 in "standby".) I think I will pass it along to someone who wants it as is.

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    Quote Originally Posted by Bill Moore View Post
    From what I have seen The amp head was around $150, and the MM upgrade kit was $300!
    I debated tweaking it, (maybe adding a switch to bypass the "bright" add on, and even a switch to put the 6V6 in "standby".) I think I will pass it along to someone who wants it as is.
    Honestly you can find them all day long on CL for $80 or so. I use one to drive my talk box. BUT.. I used it for years into a "1x12 open back cab loaded with an Eminence. With an OD pedal and a compressor I played with a live drummer all of the time. Stock, even down to the Chinese tubes. Mine wasn't particularly bright. I used a Strat mostly on the bridge pickup. I like these little amps as is. I'm not so sure what a MM OT is going to get you other than bragging rights, lol!

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    I know you can get stock used one's cheap, I contemplated using one for a stand alone reverb conversion.
    There is a little more involved in the MM upgrade than an OT!
    Here is a copy of the upgrade details.
    http://www.danbecker.info/guitars/20...anual%20V2.pdf

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    Last edited by Bill Moore; 10-26-2018 at 05:52 PM.

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    Old Timer olddawg's Avatar
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    I considered doing a stand alone Reverb conversion myself. Then I compared a vintage Fender unit to a modern pedal and and had to ask myself why? Lol. Same thing with these conversions. It’s a simple 5 watt amp. I think you will get more versatility out of the speaker you use and the pedals you choose. I’ve said this before. I had an old ratty 1960 Ampeg Rocket amp loaded with an Eminence. I would set the stock VJ behind it and simply plug it into the speaker. People would freak out about my “vintage amp tone”, lol. The Rocket was basically an open back speaker box.

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    Quote Originally Posted by Bill Moore View Post
    I know you can get stock used one's cheap, I contemplated using one for a stand alone reverb conversion.
    There is a little more involved in the MM upgrade than an OT!
    Here is a copy of the upgrade details.
    http://www.danbecker.info/guitars/20...anual%20V2.pdf
    Thanks for posting that Bill, I haven't studied the schematic but this is definitely more substantial than a simple TX upgrade.

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    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

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    yes,that mod with the bright cap is definitely different from stock,i had one of these amps for fairly long time and its pretty good quality,tried all the possible mods and ended up with a Bitmo tone control in front of the volume and smaller cathode bypass caps,that allowed me to obtain any degree of brightness,a fairly good clean tone without losing too much bass and a pretty good overdriven sound involving the power tube saturation.
    Obviously if you want more control over the total gain you can include a feedback champ style,but to me it gets too sterile for a guitar sound.

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    I find it amusing to see they refer to "generic EL84" & "generic 12AX7" tubes... As if there were anything else that a modern amp would come with? And if I'm not mistaken, any modern-production tube is pretty "generic?"

    Not saying the mods don't sound good (never tried one of these amps) but I like some of the marketing facts...

    Justin

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    "... If an older Boogie and classic Marshall had a (clearly illegitimate) child and you baked it in an oven set to clown shit crazy." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by Justin Thomas View Post
    I find it amusing to see they refer to "generic EL84" & "generic 12AX7" tubes... As if there were anything else that a modern amp would come with? And if I'm not mistaken, any modern-production tube is pretty "generic?"

    Not saying the mods don't sound good (never tried one of these amps) but I like some of the marketing facts...

    Justin
    Well when you say generic you're not giving a nod to China.

    nosaj

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    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

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    Bill, was there something that you didn't like about post #8 that you could comment on?

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    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

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    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by g1 View Post
    Bill, was there something that you didn't like about post #8 that you could comment on?
    I had the same doubt when I saw the negative

    Unless it was a mistake and Bill removes it

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    Juan Manuel Fahey

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    Some of us (Tom Phillips & myself) have noted that on a tiny phone screen, sometimes it's hard to hit the proper thumb with our big thumbs. Besides, I'm a bass player mostlyv- how much finger coordination do you expect from me?

    Justin

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    "... If an older Boogie and classic Marshall had a (clearly illegitimate) child and you baked it in an oven set to clown shit crazy." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    Sorry about that! I'm using my tablet, and with the slow wi here at home, I didn't see the negative!
    (of course I meant a positive!)

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    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by Justin Thomas View Post
    I find it amusing to see they refer to "generic EL84" & "generic 12AX7" tubes... As if there were anything else that a modern amp would come with? And if I'm not mistaken, any modern-production tube is pretty "generic?"

    Not saying the mods don't sound good (never tried one of these amps) but I like some of the marketing facts...

    Justin
    Oh, I understood it as: "don´t spend $300 on NOS tubes ... but on MM iron instead "

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    Juan Manuel Fahey

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    I'd spend $300 on anice speaker cab... You know, important stuff!

    Justin

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    "... If an older Boogie and classic Marshall had a (clearly illegitimate) child and you baked it in an oven set to clown shit crazy." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    How much tone improvement do you get by swapping the mains transformer? The original "sounds" fine to me.

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    There ARE certain "construction technique" that a cheap tranny may use, which JMF has been kind enough to more than amply demonstrate here in the past, but that has no bearing on sound...

    Mainly in using that super-skinny wire with the scrape-off or solder-off insulation that takes no punishment or adverse condition before shorting. But that's a construction problem, not a tone one...

    Justin

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    "... If an older Boogie and classic Marshall had a (clearly illegitimate) child and you baked it in an oven set to clown shit crazy." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by Justin Thomas View Post
    There ARE certain "construction technique" that a cheap tranny may use, which JMF has been kind enough to more than amply demonstrate here in the past, but that has no bearing on sound...

    Mainly in using that super-skinny wire with the scrape-off or solder-off insulation that takes no punishment or adverse condition before shorting. But that's a construction problem, not a tone one...

    Justin
    Well we're talking a 5watt chinese amp that's like putting 5000 paint job on a Yugo if anyone remembers those(kinda like a gocart with a roof and sides.
    nosaj

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    Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

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    Quote Originally Posted by Bill Moore View Post
    Sorry about that! I'm using my tablet, and with the slow wi here at home, I didn't see the negative!
    (of course I meant a positive!)
    That's what I figured probably happened, but I didn't want to box you in a corner (in case you really disliked it) by asking if you pushed the wrong button.

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    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

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