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Eric Clapton Mid-Boost Help/Advice

Discussion in 'Stratocaster Discussion Forum' started by guildguy516, Mar 14, 2017.

  1. guildguy516

    guildguy516 TDPRI Member

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    The goal here is to simplify my gig-rig, eliminating all pedals and extra guitars - showing up to a gig with guitar and amp. This simple set up is how I play at home and I have noticed much more attention is given to my technique, resulting in a better quality playing and tone.

    My Strat is always my go to ax. To achieve the simplicity, yet versatility needed to get through diverse set lists, I researched different mods/preamps to give my Strat the extra balls to crank through some heavier rock songs where I'd usually use a guitar equipped with a humbucker. I settled on the Eric Clapton mid boost circuit.

    I have installed a set of David Allen pickups in my Strat, which I absolutely love and do not wish to alter their tone in anyway. I understand by adding the ECMB to the circuit it is always engaged, therefore always influencing the pickups natural tone. To control its interaction in the circuit I would install a DPDT switch to toggle it on or off. I know this invites the unwanted *pop* when engaging but I will not be toggling it mid song - it's more of a setting I would adjust in between songs to change the voice of the guitar.

    I have read on other forums where people have installed this switch and realized the stock LACE pickups are weak and do not sound good with out the influence of the preamp. All the audio examples I could find were people playing EC sig Strats, obviously with the pickups and mid boost that were designed to be married. Without having an example to compare to I developed a concern:

    I already enjoy the voicing of the pickups as they are, which is why I would install the DPDT. If I engage the ECMB while the master volume is at 10 and slowly turn up the mid boost, will it be a fluid volume change, like 10, 11, 12, 13(with increasing mids)?

    Or will it be more like starting on 15 when it is switched on (sudden volume spike) and then thicken up so much it becomes unusable because I am using it with pickups that it was not specifically designed to be used with?

    I do appreciate everyone's input!
     
  2. Jules78

    Jules78 Tele-Holic

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    The reason they put lace sensors in is because with the mid boost engaged there is too much noise from regular single coils. Noise might be your surprise problem. I would get a new pickguard with midboost and lace sensors and try it. Then swap your pickups and see how the noise level is. I've always found the midboost to be reasonably linear the volume difference is nominal at lower volumes but it does get louder quickly when you go past halfway and then it sorta levels out a bit near the max. I personally don't like lace sensors, and find that I can get better tone from regular pickups and a single pedal like a tube screamer or Klon. There's no guitar knob to turn exactly to where you want and you can set the volume too. Everything is done through a pedal you can just step on.
     
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  3. guildguy516

    guildguy516 TDPRI Member

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    I appreciate your input on the linear-ness of the sound, it was a concern of mine.



    I initially thought that the ECMB would boost the noise too but I've read several threads where players have installed it and it DOES NOT boost the noise. I am definitely going to try it out and if I find it to be noisy I will report back here.
     
  4. Andy B

    Andy B Friend of Leo's Silver Supporter

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    Check out a Stratoblaster. Fits in place of the stock jack plate.
     
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  5. guildguy516

    guildguy516 TDPRI Member

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    Let's sightly stray from the original reason of the post, let's talk about a bypass to the preamp.

    I've read that when a DPDT switch is installed, and the preamp is taken out of the circuit, you lose volume control. Looking at the schematic I can see why: the preamp is integrated with the guitar circuitry. There must be a way to put it after the output from the pot, making it much more like a pedal train but maintaining control on board the guitar.

    Or a could a simpler solution be to modify the 50k pot, cut the carbon fader from touching the first lug, and making it just like a "no load" tone pot?

    And add a jumper from the middle tone lug to the first volume, like a standard circuit. Then the 50k would only employ the preamp after 1. Thoughts?



    No opinions here, strictly electrical facts: I'm trying this no matter what!
    I'm Polish and I'm stubborn.
     
  6. guildguy516

    guildguy516 TDPRI Member

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    Sorry, I got that slighty wrong. The volume is the 50k pot.

    Could you not install a 250k no load for the preamp and jump the tone to the volume pot?
     
  7. awasson

    awasson Poster Extraordinaire Silver Supporter

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    Ok I may be able to shed some light on integrating one of these without the 50k volume as well as a few other observations.

    Noise isn't a problem with the preamp or at least is isnt with the clone I built when I use it with my telecaster. I downloaded the schematic from several sources and they all showed the same circuit, components and values so I'm pretty confident I have a correct clone of the preamp and it works as advertised.

    As noted by @Jules78, the mid boost is linear. I don't notice a lot of volume increase but the tone thickens up and if you pin it, you'll get some fat overdrive.

    Initially, I built mine as per the design with the volume control and mid boost but I wanted to do exactly what you're doing so I bypassed the designated volume control by connecting the green wire volume pot wire directly to the brown volume pot wire. The brown will still connect to the mid pot.

    I documented my approach on the tag board effect website on the Clapton Preamp page; right at the very bottom of the page: http://tagboardeffects.blogspot.ca/2014/02/fender-eric-clapton-25db-mid-boost.html

    In order to overcome pops when you switch the circuit back online, I would take the preamp input to ground when it's on bypass. That might be enough to do it.
     
    Last edited: Mar 15, 2017
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  8. 24 track

    24 track Doctor of Teleocity Ad Free Member

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    I set up 7 pick guards with different pick ups , so i could experiment with different wiring excetera ( the first 2 pickguards are the originals untouched from the 2 strats I have) I digress,
    what I found to be the quietest were the Lace alumatones with a 3 way switch 1) neck 2) neck/ Bridge 3) bridge , I took out the middle tone control and made it a volume control for the middle pickup that I could bring in /out as much or as little as I wanted I replaced the tone control with a TBX tone control, ( 96 American Strat)
    the second Pick guard I love is the Lace sensor Rainbow pack, same wiring as above but with 1) lace Blue Neck 2) silver middle 3) Hot gold 13K bridge ( 78 american strat)
    other pickguards I have are Fender noiseless / Lace sesor reds and VanZant/ Mighty mites / you get the picture

    but out of all of them the Alumatones sound the best, followed very closely by the rainbow pack, hey and if I need a new guitar I change a pickguard!

    (Notice the Dave Gilmour whammy bar)

    DSCF0027.JPG DSCF0028.JPG
     
  9. guildguy516

    guildguy516 TDPRI Member

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    Do you have a complete wiring diagram I could follow? Would a push/pull work to through the signal to ground when it is bypassed?
     
  10. awasson

    awasson Poster Extraordinaire Silver Supporter

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    I don't have a diagram made up but I can sketch one out pretty easily. I do have an idea about using a pull-pot or just a DPDT toggle that shunts the input to ground too. I'll sketch something out in the next little while and post it here.
     
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  11. guildguy516

    guildguy516 TDPRI Member

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    Thanks! You rock!
     
  12. awasson

    awasson Poster Extraordinaire Silver Supporter

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    Thanks, I'm using a DIY layout program to do the layout. It's almost done now. I'll upload it tonight or tomorrow. I haven't tried the true bypass that shunts the preamp input to ground so I'll wire that into mine and give it a try to see if it makes it behave better than just a straight bypass switch.
     
  13. awasson

    awasson Poster Extraordinaire Silver Supporter

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    Ok, here it is... I haven't tried the Bypass with the shunt to ground yet to see how effective it is but I'll give it a try tomorrow and report back.

    ECP-True-Bypass-Standard-Volume.png
     
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  14. awasson

    awasson Poster Extraordinaire Silver Supporter

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    Ok, I got pretty busy with work so I didn't have a moment to wire up that true bypass switch until tonight. Anyway, mission accomplished, the bypass works great. I get no pop or bad side effects on mine. I haven't installed it in my guitar yet. It's going in a Telecaster and I need to do some routing for the battery box and under the pickguard for the preamp unit so for this evenings test it was a mess of wires with patch cords in/out and a pull pot doing the bypass/mid boost.

    I wired the pull pot backwards so in the in position it was on and out position off which was inconvenient but when it goes in my guitar it'll be a mini-toggle anyway.

    So how's it sound? Pretty good, I'd say.

    There is a notable boost in clean volume when you engage it with mid completely off. It doesn't seem to colour the tone; its just a louder version of the guitar. Start rolling on the mid boost and it does get a little louder but it also gets compressed so it's not overly loud; just fattens up the tone. I could see using the mid-boost rolled to 50% for giving some bite to rhythm, maybe up to 75% for the bridge pickup and you can get all sorts of lead tones anywhere on the spectrum. 100% might be too fat/muffled for some pickups when playing rhythm though.

    I'm really happy with the bypass taking the input to ground. That really works well.

    Anyway, I hope that helps you with your project.
     
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  15. guildguy516

    guildguy516 TDPRI Member

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    This is a lot of help, thank you so much!
    Did you experience any oscillation using a 250k for the volume? I have read on other forums this might be a problem.
     
  16. awasson

    awasson Poster Extraordinaire Silver Supporter

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    Nope, zero oscillation because we're not using the volume the way it's used in the original Clapton Strat wiring.

    Rather than connect the volume pot to the green/brown and ground the way they do in the Clapton Strat, I've bypassed that part of the circuit by connecting the green to the brown and then the signal comes in on the yellow line and is being attenuated by the regular 250k volume pot.

    It will never oscillate/squeal with the way I've wired it.
     
  17. guildguy516

    guildguy516 TDPRI Member

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    Thanks!
    I wired it up late last night and am very happy with the end result. I put in a 5 way super switch, wired it up B, B&M, B&N, M&N, N...put a TBX tone control, modded with .001 mf cap for more treble roll off and the mid boost with a push/pull for on/off operation. It's a great set up and I really appreciate all of your help here. Also, no POP when switching it on.
    You rock!
     
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  18. LoveHz

    LoveHz Tele-Holic

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    Until last year we had a guitar player in the band who played a Clapton Strat with Lace pickups. I have to say I never thought it sounded particularly good, with or without the active circuitry engaged. His standard Mexican Strat sounded much better to my ears.

    While I appreciate the OP's wish to get back to a one guitar and one amp setup, I'd bite the bullet and allow just one decent boost/drive pedal into the signal chain between the amp and a Strat with good passive pickups. A Fulltone maybe? I just don't get on with active circuitry!
     
  19. awasson

    awasson Poster Extraordinaire Silver Supporter

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    Awesome! I really like the ability to switch it on without the mid boost to give it a little extra gain without colouring it and then fattening it up with the mid boost when I need it. I've got to get busy with my router to install mine and make it a permanent fixture on my telecaster.
     
  20. guildguy516

    guildguy516 TDPRI Member

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    I've been using the midboost in the same Strat a little over two years now and I wanted to share my experiences with my setup and seek a little more help.

    My Strat is set up like so:
    1.Bridge
    2.Bridge + Middle
    3.Middle
    4.Bridge+Neck
    5.Neck

    -Master Volume
    -TBX (with resistor removed and .001 cap - at indent control is bypassed)
    -push/pull that turns on mid boost and sweep works as it would adding mids

    I do not have noiseless pickups installed and there is no increase in noise when the boost is activated.

    I routed a cavity under the guard, where the body is held on the paint rack and the 9 volt I put in the jack route. I cut the fingers off of a rubber glove and put both inside the fingertips to prevent moisture and grounding issues.

    I play this guitar almost every day, at every gig and it is pretty much perfect; after using it so often I have only two minor logistical complaints:

    1. Because of the short sweep on the TBX control I feel there's not a lot of range on each tone control, the affect the capacitor has when brought into the circuit is quick and difficult to dial in precisely.

    2. When the midboost is engaged via the push/pull, there is a noticeable increase in volume as well, even when the control is at 1. I have been trying to figure out ways to decrease the decibel increase while maintaining the boosted middle frequencies. Also, a control that has an off at 1 (or 0) would be so much easier to use.

    Anyone have input on lowering the volume increase of this Clapton boost?

    Also, sources for a potentiometer that has an off at the beginning of the sweep instead of push/pull?

    Thank you!
     
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