4 Holes, 1 Amp! Jumping vs Switching (+poll)

Discussion in 'Amps and Cabs' started by HeavyCream, Sep 15, 2019.

Jump vs Switch

  1. 4 Holers are king!!!

    38 vote(s)
    90.5%
  2. Cascade classics rule

    3 vote(s)
    7.1%
  3. All hail the Twin Reverb

    1 vote(s)
    2.4%
  1. Funky54

    Funky54 Member

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    Not always. In fact usually two holes are for one channel. Hi/Lo per each channel (two channels) = 4 holes

    For instance... My 1965 AC30 has 6 holes. There is a high input and a low input for the top boost channel.... there is a HI/LO inputs for the Normal channels and there are HI/LO for the Trem channel.

    I place a patch cable into the top boost “high” channel to the Normal channel “low” input.. then I plug my board/guitar into the normal “high” input. So I’m using two channels blended (Normal with Top Boost) It sounds much much better than just using one channel. The Top Boost channel is a bit bright but it has three EQ knobs to tailor the tone. The Normal Channel has no EQ and is a bit compressed and thick. Put them together and you can tailor the volume knob of each channel and the three EQ knobs to the Top Boost Channel. Together, I get the sparkly Jangle while still having that mid thick compressed Brian May eschew tone.
     
    Last edited: Sep 17, 2019
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  2. michael patrick

    michael patrick Supporting Member

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  3. Steppin' Wolfe

    Steppin' Wolfe Member

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    I have an interesting four hole amp...a Rickenbacker B9A, which is a single 6V6, 1 x 12—-OEM Jensen C12Q, and a solid copper chassis. Yes, it is a single channel amp with four inputs. It is interesting to daisy chain across two extra inputs as that decreases the input resistance for a gain boost.
    My other four holders are dual channel vintage Fenders. The 1964 (Dual) Showman has a modded Normal channel, and it is interesting to chain it to the Vib channel. It sits in a Fender Pro Sonic cab, which will soon get 2x EVI Force speakers. With the Ab165 Bassman and its progeny through the Bassman 50, chaining in the Bass channel adds low end beef just as chaining those Marshall’s does.
    Single coils need this, ime, when using an old Marshall 4 holer....as Jimi well knew.
     
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  4. ripple

    ripple To keep fresh, keep capped & cold. Silver Supporting Member

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    I love the old 4 hole amp circuits! I constantly rotate between my JTM45, JMP50 and Tweed 5F4 Super clones, and always jump the channels at gigs. Love the extra control it gives me in matching the amps EQ to the room acoustics. Those old amp circuits are surprisingly versatile.

    For noodling around the house, I'll hook up an A-B-Y pedal to get different channel voicings on the fly, or use a 1/4 footswitch to switch between lo and hi inputs for a solo boost. Sometimes I use the 1/4" footswitch trick to balance out guitars with different output levels (i.e. Les Paul vs Strat/Tele).

    I recently built a Trinity Triwatt (33 watt Hiwatt clone) that is a 3 holer, with the third input internally jumping the Brilliant and Normal channels. I always use that input, and love that feature, as it saves me a patch cable.
     
    Last edited: Sep 17, 2019
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  5. PurpleJesus

    PurpleJesus Internet Moderator/Super Hero Staff Member Supporting Member

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    Ummm.....epic 4-input Hiwatt's say :wave
     
  6. Penguinchit

    Penguinchit Member

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    @Funky54 Thanks for the explanations. That helps me understand quite a bit. Seems like instead of having something like a boost button, there's a lot more flexibility...
     
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  7. Funky54

    Funky54 Member

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    Yep, cool stuff. In my past I used them sorta like an effects loop with echoplexes on the two wet amps. It was an awesome discovery for me. I remember a local guy showing me that when I was like 21, 22 years old. I got that one trick early. A harder lesson was learning why My sound would become muddy or gone in the live stage mix. I didnt get the cancelation thing (thanks bassists with 8x tens and a 5 string playing in my frequencies) until much later. It was an issue that plagued me for a while.
     
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  8. Tone_Terrific

    Tone_Terrific Supporting Member

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    It's basically a mixer with 2 channels, usually limited, or shared eq and the blend options depends largely on the voicing of the channel.
    M's typically are too bright in one channel and too bassy in the other, easily jumpered to allow a blend. Standard technique forever with these amps.
    Any further options require more external hardware.
    The inputs do not cascade i.e. stays parallel like a mixer. It's not a trick for high gain.
     
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  9. Echoplexi

    Echoplexi Silver Supporting Member

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    Another one of the greatest sounding 4 hole amps I’ve had was a Magnatone 213. That thing was amazing
     
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  10. De Batz

    De Batz Member

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    Don't see AC50 mentioned in the thread so far. My '67(ish) does just about anything my old JMP50 did, and the brilliant channel gets close to AC30 with the right speakers.

    Two fully independent channels with their own eq controls, different to several of the examples mentioned. Might be the best single sound I can make, that channel mix.
     
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  11. 70' s Tone

    70' s Tone Member

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    The Four Supro Horseman of the Apocalypses... ;)
    (1) Supro Coranado - 6L6 power tubes - 5U4GB tube rectifier
    (2) Supro Big Star - 6973 power tubes
    (3) Supro Black Magick - 6973 power tubes
    (4) Supro Dual-Tone - 6973 power tubes
    Plugging into IN 1+2 links both preamp channels in parallel for double the input signal and double the gain. This clever topology lets you hit the power amp as hard as necessary and even allows “channel switching” in its purest form, using a simple A/B switch.
     
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  12. rumbletone

    rumbletone Silver Supporting Member

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    What I’m currently contemplating is changing the 2 triodes so one is a typical plexi and the other is similar to the 2203 2nd triode (cold clipper), and the switching inserts the 2nd triode in series (as well as either adding a master volume just for when the 2nd triode is engaged or switching between 2 different master volumes). I am expecting to need to cut some low end at least for the series mode, so will plan to try some different coupling cap values.

     
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  13. HeavyCream

    HeavyCream Member

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    @Funky54 and Tone Terriffic gave you some great info. The post above talks about how the input channels are in parallel, that’s the key. Often one is dark and one is bright so mixing them together to taste by rolling the channel volumes offers a wide range of tones.

    What really makes them special for me is how those parallel gain stages produce a rich, complex breakup. An overdriven 1959 or 5E3 is “the sound” of rock n roll. Power tube crunch, OT, speakers certainly play an important roll but, the preamp circuit has a huge impact on any amps tone/character. As mentioned above, it’s not a high gain thing. More of a sweet dynamic OD/breakup.

    If you’re interested in this sort of thing but don’t have the right amp or the means to get one, there are some pedals that do a pretty good job recreating channel jumping. Another cheap way to get a taste is the Frenzel tube preamps. There’s also some tricks you can do with pedals, splitters and fx loops.
     
    Last edited: Sep 18, 2019
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  14. HeavyCream

    HeavyCream Member

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    Ahh, sounds like a killer amp! Hope it works out and I hope you post some pics when she’s naked ;)
     
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  15. Uli Jon Blackmore

    Uli Jon Blackmore Supporting Member

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    It is so cool. It's almost like you have different channels that have different levels of gain and a different EQ focus. Its astounding how this has missed all subsequent designs. It is also astounding that somehow the added patch cords and possible a/B/X boxes absolutely do not degrade the audio quality, but any possible switching invariably does.
     
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  16. HeavyCream

    HeavyCream Member

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    Doesn’t having the jumper patched in sort of defeat the purpose of using the ABY switcher? Maybe it doesn’t come through so well in the video but it sounds like no difference between the A and AB settings.
     
  17. michael patrick

    michael patrick Supporting Member

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    It's subtle, but there's more gain on the A+B setting.
     
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  18. pete12string

    pete12string Supporting Member

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    I have a JTM 45 with a 2x12 closed back cab with Celestion Greenbacks.
    I’m under the impression that the Bluesbreaker is a JTM 45 with Tremolo.
    Would you call it different from a JTM because of the Tremolo? Just curious.
    The Marshall 18 watt (1974 1x12) with 2 Normal inputs and 2 Tremolo inputs is another one.
     
  19. prsjcm

    prsjcm Member

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    I love four hole and vertical input Marshall's. I also adore the crap out of my Silver Jubile reissue. Up next in my amp que will be a four hole 1987.
     
  20. roadfilm

    roadfilm Member

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    I've been using a Y cord to run both channels of my low power tweed twin. It's an awesome sound but I was wondering if I could just use my BOSS DD-5 delay pedal and run both channels using that instead of the Y cable. Would there be any negative effects?
     

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