Bass Mid Control by E.W.S. schematic  [schematic]

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apollomusicservice
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Post by apollomusicservice »

Active mid controller for bass players.
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Bass Mid Control  (E.W.S.).png
001.jpg
002.jpg
003.jpg
004.jpg

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tube-exorcist
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Post by tube-exorcist »

IMHO the C50k ist the stereo-poti and used for the frequency and the B100k is used for cut/boost.
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apollomusicservice
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Post by apollomusicservice »

Thats right, on schem R10=B100k and R11=2x C50k.
IC part number is scratched and cleared and I suppose
that it could be 4558 (or some other dual opamp).

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Post by tube-exorcist »

apollomusicservice wrote:.... on schem R10=B100k and R11=2x C50k....
I think my eyes must fool me, but on the schematic above I see R10 = C50k and R11 = B100k.....
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."

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Post by apollomusicservice »

tube-exorcist wrote:
apollomusicservice wrote:.... on schem R10=B100k and R11=2x C50k....
I think my eyes must fool me, but on the schematic above I see R10 = C50k and R11 = B100k.....
Thats right, on schem should be R10=B100k and R11=2x C50k.
IC part number is scratched and cleared and I suppose
that it could be 4558 (or some other dual opamp).

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rafammbass
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Post by rafammbass »

Is it me or ther is no tantalum capacitor on this schematic?

Can you check?

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apollomusicservice
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Post by apollomusicservice »

rafammbass wrote:Is it me or ther is no tantalum capacitor on this schematic?

Can you check?
On schematic C2 marked as 2u2T is tantalum capacitor.

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Post by quaternotetriplet »

can you please clearer pictures? some of the guys might help you from tracing this circuit.

Thanks! :applause:

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Post by apollomusicservice »

For those who wants to make this pedal here is my design of the pcb. 8)
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BMC pcb.pdf
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BMC components.pdf
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darmstat
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Post by darmstat »

Hi....Does anyone know where to find the Potentiometer for the E.W.S. Bass Mid Control?

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Post by triplesevener »

darmstat wrote:Hi....Does anyone know where to find the Potentiometer for the E.W.S. Bass Mid Control?
The stacked pot is most likely custom. If I were to build this, I would just use 2 pots.

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IvIark
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Post by IvIark »

Here's a vero layout

Image
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Post by jop120 »

Hi everyone, I was thinking about having a go at making a dual band version of this pedal, by using an AMZ JFET Splitter before each band and then mixing it again with a buffer at the end, in hope that it won't be too interactive between bands like other dual band para's that i've played around with.
The idea would be to have the first band working in a range from about 100-600hz and the second band going from around 500hz-4Khz. would changing the band range be as simple as altering values of C8 and C9?
Does anyone know of a reason why making a dual band in this way wouldn't work?

thanks very much

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Post by cylens »

Hi there,

has anyone succeeded in having it built and working OK? I've used IvIark's layout.

It took a long time to source a dual C50K and unfortunately the frequency control is reversed (double and triple checked the pot numbering) and stuck in the last quarter of the pot: when boosting, there's a mid-freq boost when the pot is fully CCW and it quickly turns to a mid-bass boost and the frequency is almost stuck there for the whole taper.

which has me thinking: could it be the opposite? dual B100K for freq???

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Post by jop120 »

Yeh, the frequency pot is backward on the schematic. I just finished prototyping my dual band version, breadboarded a single band one as well to check it out and adjust my frequency bands. After posting my last comment, I had a think and realised putting the bands in series would be the way to do it, just before going to the output cap, repeat everything from after the tantalum coupling cap and alter C8,C9 & C10 for different frequency bands.

for my proto's I used a dual-gang B50k, cause its hard to find the C-curve pots, but it definitely needs a C if you want to get the most out of it. there's someone on alibaba selling them in packs of about half a dozen, but not sure of the quality yet. Alternatively if you can find a brand of pot that makes a dual-gang A50k pot that can be dismantled without destroying the pot, it might be possible to swap over the two tracks (often on a dual-gang one track is a reverse of the other as the wipers are both on the inside) to get a dual-gang C. I suppose you could also just use an A-curve pot and wire it backwards like the schematic and learn to live with the fact that it works in reverse.

I also found by adjusting R14 you can adjust the Q, you need to adjust C7 to compensate, its quite nice to have a switch allowing you to choose a flatter or sharper Q, especially with a dual band version.

definitely a great pedal to have on your board and works great for both bass and guitar.

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cylens
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Post by cylens »

Yes, lugs 1-2-3 are reversed for the dual gang pot, works great now. Here's where I found my C50K duals: https://www.ebay.com/itm/5-x-C50K-Poten ... 0178194276

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Post by apollomusicservice »

So as not to confuse the builders, this is corrected schematic. But my friend who deals with hi-end hi-fi, has a personal theory that the potentiometer which turn in cw direction have to reduce the audio signal in analogy of with various valves that we are using (for example, turning valve for water, gas... in cw direction we are reducing the flow). 8)
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Bass Mid Control  EWS.png

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jop120
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Post by jop120 »

Thanks for the ebay link Cylens, they look like the same ones i found on alibaba, but better to get them on ebay with paypal n all.

Cheers for the updated schematic Apollo, this is a really useful pedal i'd recommend to anyone looking for a new project.

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chicago_mike
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Post by chicago_mike »

Man, I thinking EVERYTHING comes from Shenzen now... :roll:
Skyline FX 2013

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lietuvis
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Post by lietuvis »

I redraw pcb if anybody interested (sprint layout 6). The PDF is ready to transfer.
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BMC 001.JPG
BMC 002.pdf
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BMC.rar
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