Home Forums General DIY Pedal Discussion Tone Tweq as bass preamp (answered)

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    I have built several pedals from scratch and with GuitarPCB boards (love em) and even hacked a few to my own liking, but all in all, I am still a noob and wanted to ask the pros.

    I am building a 5 string bass and want to try to build the pre-amp myself. I want to be simple and really not alter the tone of the bass much if at all. (I am typically a passive guy anyway.) I tried several designs and then shelved the idea opting to just buy an aftermarket preamp. As I was looking at adding a Tone Tweq to some older pedal designs to make them awesome, I started to ponder the idea of a Tone Tweq as the EQ portion of an on-board bass pre or the entire pre itself. I am not sure it could be used stand alone in this manner and have the same effect as a full preamp. Although, it my limited knowledge is making me think it could. I am just trying to figure out the following looking on this site and others for reference. Would definitely appreciate any input, thoughts or even different ideas with other boards. Thanks in advance.

    1. Is the Tone Tweq enough by itself to simply add a volume and a blend pot off-board to be the full preamp?
      I was thinking of taking the Emexar built as the MicroAmp and then combining with theTone Tweq for the full build, but can’t decide if I really need the Exemar-MicroAmp in this onboard preamp application. I am not looking for dirt, just strong clean signal with EQ boost and cut options.
    2. What are some good options for wiring it so a push pull pot could switch between active/passive?
      I have seen several options in online research and I lean towards one pot being a stacked pot with one knob being the passive tone when in that mode. I am just not sure what the best knob is out of volume, blend, hi, mid and low would be to have that stacked pot for passive tone.
    3. Even though the Tone Tweq is a shelving EQ, would using a DPDT board with different cap/resistor combos create the ability to shift the frequency emphasis (of the mid-range for example)?
      This is really a bonus question, but is a feature on higher end on-board bass preamps. So, I thought I would ask you smart folks.

    I could answer these questions however I know that Wilkie (who is currently on Vacation) has been working on ideas like this for some of his clients in Colorado. I think it would be best to allow him to put his thoughts to this when he gets back. There are a few sorta yes and maybe not answers to some of the questions and much is certainly subjective and there may be ideas you have not yet thought of.

    I would prefer to wait for Wilkies input based on some of the projects he has recently been working on that we have been discussing and I certainly do not want to steal any of that thunder.


    No worries, Barry. I am not in a big hurry as this is a personal project. Just looking to learn. Thanks for the reply and happy to wait on Wilkie.


    These are the response curves for the Tone TwEQ.  You will note that the mid frequencies are centered at 1K.  The Bass and Treble filters are shelving types.  So the Bass filter easily covers all of the lower frequencies you will use with a 5 string bass.  However, if you change the Mid filter by changing the cap and resistor values, you will cause that filter to overlap the bass filter even more than it currently does.

    Now, to discuss the use of this as an “ON BOARD” preamp.  Keep in mind that this device uses four pots.  Each filter has a pot for boost and cut and there is a final volume pot which sets the output level.  The output can be much higher than unity and it is also a low impedance output.  So it can serve as a preamp.  Because it has 4 pots, it is probably not a good choice to mount inside of your bass but would be great as a pedal!

    I have had several requests for building a combo floor pedal that incorporates the Tone TwEQ as a final EQ/preamp/low impedance output with multiple outputs serving as a DI box with balanced XLR and TRS outputs as well as Normal & inverted outputs with phase switch, etc.  Also, keep in mind that many bass players use compressors and even distortion/fuzz.  These can also be combined into combo pedals that our builders create.

    I hope this answers your query and also gives you some ideas for future builds.


    Thank you so much for the response. Yet another wilkie1 post where I learn things.

    The output can be much higher than unity and it is also a low impedance output.  So it can serve as a preamp.  Because it has 4 pots, it is probably not a good choice to mount inside of your bass but would be great as a pedal!

    In your statement above, is the only reason you think it would be difficult as an on-board pre is the number of pots? I ask because I have active basses with 5 knobs. With the tone tweq I can actually stack the treble and mid into one hole…add a blend or volume fo the other pickup and I am still at 4 holes which is usually about standard for an active bass.

    I am trying to understand what changing the pot values on the tone tweq would do as well. Can you point me to some good references that might help me understand the affect of the Ohm value in a circuit like this on the output frequency?


    Sorry, but I’ve been down sick for a few days.

    When changing the values of the resistors, capacitors or pots in filter circuits, the overall balance of the response changes.  The shape of the response curves, the amount of boost and cut and the Fc of each filter can change.  If you wish to experiment with the response of each filter, I suggest you build a Tone TwEQ using sockets so you can experiment with the response.  This would best be done outside your instrument to facilitate component changes

    Here is a good reference for understanding filters:  http://sound.whsites.net/dwopa2.htm#s7

    You can find excellent concentric pots in a variety if values at:  http://smallbear-electronics.mybigcommerce.com/alpha-dual-gang-9mm-pc-mount-dual-concentric/ 


    Jamye- great idea!  I am going to play around with this.  I have a couple basses in the works, and I’ve been trying to decide what preamp to use.  I will try to come up with a rough schematic of how to run it active/passive.

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