Tuesday, February 5, 2019
EWS Tri-Logic Bass Preamp II
Here's a pretty simple but effective bass preamp from EWS. It's a 3-band EQ being pushed by a MOSFET gain stage. Looks like EWS made a version for Xotic with the same name. Not a lot different between the two other than some value changes laid out in this schematic on FSB. I've laid it out for a 125B with top mounted jacks. It runs off an 18v supply so use your favorite charge pump if you want to include that in the pedal.
Hey Big D! Noticed no one has commented or verified the last few layouts. Just wanted to let you know that, while I don't have the time to build everything you lay out, I'm still watching and very appreciative of the hard work and time you put in to all of this. Thank you for all you do!
ReplyDeleteThanks Peter!
DeleteNice, ill try to build this as soon as college lets me, im trying to make a b7k so adding this to the b3k here might get me somewhere.
ReplyDeleteThanks for all the hard work.
not build yet... just check the schematic, looks like everything is fine... only the active/passive is wrong concept, when switch to active its must be drop the signal with 100K.. not 100K to ground..
ReplyDeletebut you doing god layout..
wow.. thanks
I think the concept of the 100k to ground is to drop que Zin (input impedance), instead of attenuating the signal adding more resistance to the path, a compromisse with noise etc...
DeleteI just Follow the schematic, in schematic active/passive 100K is not to ground
DeleteYes, I got your point, but the electrical effect still the same, can you figure it?
DeleteIn time, I tried by routing myself the board and got a quasi non effectiv mid knob... I'm gonna re-buil it
I'm gonna try the layout this week and fedback here.
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ReplyDeleteI just waiting for Omni Cabsim from "noise maker" layout....
ReplyDeleteHehehehe... god job, this my favorite blog.
Good Day! It is verified. For volume I used A100k.
ReplyDeleteIt works as well as the product version of Trilogic3 I have. While it is a quite versatile EQ, it does not color your tone like Bartolini, Eden and others.
Always I thank you for all the great works here. This blog makes my DIY life so vivid!
Thanks for verifying and for the kind words!
Deletewhy some electrolytes don't have polarity? whats the correct way?
ReplyDeleteAt least according to the schematic, yes.
Deletewell, that means those electrolyte polarity is not important??
DeleteNo, you need to use non-polarized caps. They don't necessarily have to be electrolytic.
DeleteHey. What kind of MOSFET is applied here? J201? 2n5457?
ReplyDeleteBS170 (or 2N7000 would probably also work)
Delete
Deleteextremely grateful
hi, I can't find small nonpolar 2.2 uf and 10 uf in local store here, can I replace it with electrolyt caps?
ReplyDeletebecause nonpolar available here, is only the big one, like in passive crossover.
I think it to big for this kind of pedal?
thanks
Very usefull stuff, good boosting bass and treble.But I had add a germanium diode at gain stage for little compression and to some colour preamp tone. Thanks for pcb, works great
ReplyDeleteCool. Did the active/passive switch work ok?
DeleteI have passive bass, so don't hear any difference at a/p switch🙄may be You nows any ways how to check this function?
ReplyDeletecan i replace it with 2n5458? thanks
ReplyDelete18V.. 😫 thot i could series it with other 9V pedals.
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ReplyDeleteit works!!! the active and passive switch works with an active music man, had no capacitors without specified polarity and used electrolytic with the negative facing the right side of the layout. thanks for the great job, i've been a huge fan of this blog for years !!!
ReplyDeleteFirst off, thanks for the fantastic web-site and all the efforts you put into this project! This is my go-to place either to buy pcb's or just have fun with perfboards.
ReplyDeleteTri-Logic is great and it worked right away. What impresses me the most is mid controls. Great addition to the Stingray's existng EQ.
Still I need pro's tip and sorry if it is a dumb question and I miss obvious thing.
I have a hum around G frequency that becomes even more noticeable as I dial up the Gain or Mid knobs, though visually everything on the board is identical to the layout.
The power unit I use for my builds seems to be OK, or at least it makes no noise when I plug it into other pedals. I managed to reduce the hum a bit by putting 220uF el cap on the power input of the board, but it is still present and produces unwanted harmonics.
Do you have any ideas how to troubleshoot/fix such a hum, like is it a ground issue, value mismatch, poor component quality, power source, etc?
Many thanks again!
Good day, Today is July 13, 2024. It is Confirmed, this is working. you can use 9V boss switching power supply. It didn't work with my 18v power supply, it will only work if you will put voltage filter. As for Active/Passive switch, it is not working with me I don't know why, I just followed what's on the diagram. Great Works here, Thank you so much.
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DeleteDid you have to modify anything? Or did you just assemble it as it is and it worked?
I just followed what's on the drawing. and I used Boss Switching power supply 9V and it worked. but if you are using unfiltered power supply it will make a lot of noice, just buy the DC power supply filter board. I just noticed the noice when the gain, volume, tribble, mid and Bass is on full Volume, or maybe it is just normal.
DeleteI also have a problem with the volume, it has a little volume, you only get a full volume when you turn it in full volume the Gain and the Volume potentiometer.
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