5E8A Tone Stack

Discussion in 'Amps and Cabs' started by althekiller, May 13, 2019.

  1. althekiller

    althekiller Member

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    Can someone explain what the eq controls are actually doing on a LPTT. I have the Fender 57’ Reissue and get great sounds out of it but it seems the treble and bass controls are really different or interactive or something than what I’m used to. They don’t react like other amps I’ve had and the volume also seems to play a big roll. The presence knob also seems to add mids kind

    I’m just mainly curious about what this amps tone stack is and why it behaves the way it does. If there are any secret settings or common setting I’m unaware of please share.

    A little off topic but this is also one of the only amps I’ve played where I enjoy the normal channel over the bright channel, but I’m sure most use the bright. And that includes at high volumes even that I prefer the normal input. I don’t really use it the amp at bedroom volumes. It gets cranked pretty frequently.
     
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  2. olkie

    olkie Member

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    I don't have experience with this amp exactly, it's more that I find the tone stack interesting in the Duncan Tone Stack Calculator (and have tried it out in some DIY pedals). I've only seen this tone stack on tweed amps.

    The treble should do what you think it would. The bass, when cranked to max should scoop out some mids... backing it down a bit fills the mids in. Lower bass settings cut below a certain frequency, but it's at a frequency that it seems more like a volume control than a bass control.
     
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  3. jhuse

    jhuse Member

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    You’re right, the tone controls behave differently than most would assume. From what I gather, both tone controls act like gain controls for their respective tonal ranges, and there is not a “fixed” mid range frequency, per se. So unlike a 2 knob tone stack like in blackfaces or a Baxandall stack, turning both up does not really scoop mids, nor does dumping both give you a mid hump. The controls are interactive but in a relatively relationship.

    One plus to this stack design is that I can turn the volume and both tone controls down and make the amp incredibly useable at low, low volume levels. It’s actually easier to play quietly on my 5e8 than my 5e3.
     
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  4. thesjkexperienc

    thesjkexperienc ^^^ I made this guitar^^^ Supporting Member

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    You can control the amount of signal that goes through the amp by turning the tone knobs up for more dirt and a bit of volume.
     
  5. zenas

    zenas Member

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    The E series Twin is a bit different than my 5e7 Bandmaster and most other big tweed preamps, in that it uses two tubes upfront. So I'm not sure if you'll get the interaction between the volume knobs like you do on other tweeds or the four input Marshalls that were based on them.
    With my 5e7 or 1987 Marshall I also use the normal channel, then fiddle with the unused channels volume to tweek tone.
    Easy to try, just turn the other volume knob and see if it changes things.
    Also with that amp you could run a 12ay7 in one channel and a 12ax7 in the other if you wanted to. I've heard of guys doing that with an ABY to select between them, the 12ax7 has more gain. Admittedly it's a circuit I haven't spent much time with though. Need to build one.:)
     
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  6. H. Mac

    H. Mac Member

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    I agree with Jhuse’s observations, and have had these same experiences with my Fender ‘57 Twin RI. The Treble and Bass controls govern their respective frequencies of course, but are more interactive than one might expect, and turning them up also increases the gain (even if the Volume knob is not turned up). And regardless of where the knobs are set, there is neither a mid scoop or mid bump. Even the Treble and Bass controls turned down, it still retains the characteristic tweed growl at low volume levels.

    The Presence control allows fine adjustment of the overall tone, and its affect is most noticeable when the Treble and Bass knobs are turned up or down, and has a more subtle effect when they’re set to around 5.

    I previously had a 5F4 close, and circuit-wise, the 5E8-A is similar, with the paired 5U4 rectiers amd the two 12 inch speakers making a major sonic difference. As with the 5F4 clone, there is no interaction between the 5E8-A Volume knobs, but this is not a concern.

    The OP mentioned his preference for the Normal channel over the Bright, and I agree with this. An A/B or A/B/Y switch allows both channels to be utilized, and there is plenty of gain on tap without substituting any high gain preamp tubes.

    I’ve been a tweed fan for almost 50 years, and wish I had discovered the 5E8-A earlier.
     
  7. HotBluePlates

    HotBluePlates Member

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    The E-series Fender amps have tone controls sitting in a feedback loop, which is why they behave unlike anything else. You can visualize their behavior with the E-series tab of the Tone Stack Calculator. You can get a Vox-like mid-scoop if you turn both controls to max.
     
  8. H. Mac

    H. Mac Member

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    I don’t know about your Twin, but regardless of settings, nothing about my Twin gets anywhere close to a “Vox-like mid-scoop,” and the same was true for the 5F4 clone I had previously.
     
  9. PerryR

    PerryR Silver Supporting Member

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    My Dr Z Zmaster uses the same tone stack. Dr Z tuned parts of the circuit around the inputs and filtering, uses a GZ34 and in general gets a bit more headroom and tightens it up a bit, but the tone stack definitely behaves just as it looks on paper.... funky! But it’s part of the recipe, as well as the funky phase inverter, its why it sounds the way it does and there is some serious cool mojo going on.

    As others noted the gain increases as you turn the treble or bass or both up. These controls essentially ‘throw away’ signal within a frequency range VS balance frequency’s like A more traditional tone stack. I find that I get my favorite sounds with the treble and bass turned up between noon and 3p, using the normal input and presence to taste. If the amp still needs a little more sparkle I will add a touch of the bright channel (which is internally jumpered on the Z master).

    The Zmaster is tweaked, so I don’t know how different it is side by side with the untweaked version, but when I get the Zmaster dialed in nice, the top end has some meat to it and the bottom is clear and tight with a ballsy tone that is well balanced with the top, and the amp rings and sings just right.
     
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  10. H. Mac

    H. Mac Member

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    Interesting! I was interested in the Zmaster because the good doctor’s webpage description of it makes it seema lot like the 5F4/5E7, and a comment he posted in the ZTalk forum confirmed it. I also saw iyour NAD thread on Ztalk.

    The 5F4/5E7 and the 5E8-A Twin use the same tone stack, and you’re right about the Doc using it on the Zmaster. Of course, the good doctor added a few tweaks, like the internal blending for the two channels.

    But while the 5F4 clone I had was really good, it always seemed to be begging for a pair of 12s instead of the pair of 10s. That’s why I went with the Twin.

    I’m not sure ithat using an A/B/Y pedal with the Twin gets the same results as Doc Z’s internal blending, but it’s fun and opens a world of possibilities.

    A surprising thing about the Twin is that it sounds really good at all volume levels - like the whole sweep is all one big sweet spot.
     
  11. HotBluePlates

    HotBluePlates Member

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    Use the link I posted, and set both sliders to Max. There is a resulting mid-scoop (that doesn't happen at any other setting) centered near 1kHz.

    In my 5F4, I never got either knob near max. I also wound up changing the cap values in the circuit to have more-useful (to me) control over the voicing. I also wound up ditching the Presence control in favor of a switch that bypassed the tone circuit completely.
     
  12. H. Mac

    H. Mac Member

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    Thanks, HotBlue. I appreciate your explanation and the link, and while I’m not trying to be argumentative, my Twin RI does not produce a “Vox-like mid scoop.” I’m being 100 percent straight with you. Regardless of settings, it retains the pronounced mids that are characteristic of the Fender tweeds. It’s a great amp!
     

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