a rare Mr. EQ build report

[powerplayj]

I didn't really have a need to build an EQ because I already a Fish'N'Chips that was dead silent and got the job done.  However, all the hype over a few boutique EQ pedals at the Gear Page gained my interest.  So, I thought why not try something other than the normal multi-band EQ?  (Seems like once you get the building fever it doesn't take much of a suggestion to start the next project.)   Besides, if it didn't work out, I didn't shell out any $$$ on an enclosure and could salvage the IC for a 3-Legged Dog or something else.

My first thought when putting it together was that it was a bit on the noisy side and therefore would never get used.  However, after trying it out with two guitars and multiple distortions along with some convincing from B Tremblay that it would be quiet once it was enclosed, I was sold. 

Basically when the volume control is at minimum, you are close if not exactly at unity gain.  There is a separate on/off switch for both treble and bass boost along with an On-Off-On switch for cutting/boosting mids (middle position is default...or off).  The frequency humps selected for each switch are quite perfect and seem to suit my tastes better than my Classic 30 amp controls and they also translate well to both a Strat and LP.  Someone started a post a few days back saying how eq gets neglected in a lot of pedal builds and after building the Mr. EQ, I can definitely vouch for that idea.  You can take a simple two knob Marshal emulator like a Thunderchief and emulate almost every Marshall classic rock tone you have ever heard.  Couple this pedal with the Dr Boogey's 4 knob EQ and you'll stay busy all night!

The coolest and totally surprise feature about this pedal is that when the switches are in the default position, it's as if the pedal is no longer in the chain and doesn't color the tone.  So, I decided against using a switch or LED and just leaving it "on" and in my effects loop all the time (the Fish and Chips are now on ice).  It fits nicely in a 1290N which is supposedly the same size as a Taiwanese B and has room to spare for a switch and LED if you are wise with the layout.  No pics yet as I have done nothing special to the enclosure and have not selected a knob or tip covers for the switches.  In a way it's sort of a secret weapon as no onlooker would have a clue as to what it does (3 switches, one knob, hmmmmm?)

I think it is definitely one of those builds that goes under the radar in how effective it is.  If you have a partcular tone but can't find the right voicing for, it is an easy way to fiddle with limited frequencies without remembering the positioning of each band of a multiband eq.  It's also easy to change the settings when switching between guitars as well.  If I was limited to choose between 3 DIY builds the Mr. EQ would have to be included along with the Thunderchief and MOSFET boost.

Thanks to the guys at ROG for this intriguing build!


http://www.runoffgroove.com/mreq.html

[KerryF]

Thanks for that report.  Great news.  I was looking at building that pedal for my first build, but decided on the Marshall Bluesbreaker instead.  I would really love to build that pedal, but a veroboard layout would help a lot with making it easier to build.  Right now I am waiting for bulk packs of parts so I can build The Pusher Boost from Dragonfly ( http://aronnelson.com/gallery/album18/THE_PUSHER_BOOST ).  This has treble and bass boost knobs and a mid/fat switch, along with a volume control.  This looks like it is close to the Mr. EQ.  However, if anyone has a veroboard/stripboard layout for the Mr.EQ, please PM it to me.

Thanks.

[PB Wilson]

Very nice info. Of the dozen or so builds I have planned, you've made me put the Mr. EQ at the top of the list.

[stm]

Good to hear you are enjoying the project.

A hidden feature of this build is that there are two spare gates there. Based on the graphs in the article, one could make two extra stages tuned to 250 Hz and 6 kH, thus being able to control body and presence as well.

Also, part of the sound of this build has to do with the slight coloration added due to the nonlinear nature of the CMOS inverters when input signal is large.

Cheers.

[WGTP]

I have been curious about using those extra stages to overdrive the EQ for sort of an EQ Distoriton Effect.  Has anyone tried that?   

[soggybag]

I had been inspired to build one one of these, and the only thing that kept from doing was the idea of thinking of something to do with the extra inverters. I should probably whip up the origianl Mr EQ first and then worry about making mods later.

[RickL]

 

I have been curious about using those extra stages to overdrive the EQ for sort of an EQ Distoriton Effect.  Has anyone tried that?

I did. I added a Craig Anderton Tube Sound Fuzz to the one I built using the extra inverters. I posted a short review some time ago.

[Cliff Schecht]

So I could build a Red Llama and a Mr. EQ in one pedal? My guess would be noise problems, but it would be great to use all of the inverters on a CMOS chip.

[stm]

Two important things to consider when attemping to use all the inverters are:

1) Power consumption. Each inverter setup to work in its linear region eats up current.  I don't know exactly how much, and depends on if you put a 100 to 470 ohms resistor on the Vdd pin of the chip, but six inverters will shorten battery life. If you plan on using a DC adapter this is of no concern.

2) Crosstalk between different stages. If you have at least one stage that's clipping, it is most likely the high frequency content of the clipped signal will leak into the others and become audible. This might not be good if you plan to build an overdrive and an EQ circuit in the same package. YMMV.

[Cliff Schecht]

So after reading this report last night, I decided to build a Mr. EQ for myself. After a good days work and about an hour of debugging (I normally do PCB's, but I got lazy and did perfboard and made a few mistakes ), I have it in good working order. I haven't really played with this thing yet, but I'm hoping that it will really help tighten my overdrive sounds as well as give me a fat clean tone.

One thing I noticed was that the mid scoop is kinda weak compared to the boost. Is it supposed to be as subtle? I think it might have been the switch I was using though, I ended up soldering on it a few times and it became kinda faulty on the cut side.

I was thinking about also building a AMZ Mini Booster on the same board, but considering this thing has a volume knob, that seems kinda pointless right now.

I'm also considering making each boost switch on stomp switches with LED's indicating when each is active. My only concern is that I'll have to use 4 stomp switches and split up the mid control, which seems a bit excessive. Maybe I should quit being lazy and just bend over to adjust the thing .

[Cliff Schecht]

Also, after studying the schematic a little, I have a quick question. How is the signal not effected when all of the switches are bypassed? I understand that letting the capacitors go to ground enables the boost, but how does the signal stay uneffected when the switches are off?