Systech Harmonic Energizer

[Mark Hammer]

I put together a clone of this, using the layout and schematic at the madbean site ( http://www.madbeanpedals.com/projects/KarateShop/docs/KarateShop.pdf ).  A present, two of the 3 controls (frequency, gain) are working as expected, but the 3rd is not.  Perhaps more surprisingly the V+ pin on the quad op-amp is measuring 4.6V with a fresh 9v battery.

There is always the possibility of an as-yet-undiscovered solder bridge (not to mention the rather dismayingly imprecise soldering with my current iron), or a malfunctioning pot, but the supply configuration shown in the schematic is unfamiliar to me, so I don't know if the unexpectedly low supply voltage is intentional or not.

Can anyone confirm or disconfirm that the supply ought to be either 9v or something much less?

[Govmnt_Lacky]

Mark,

Two things that I noticed after skimming the info:

1) It appears that the layout does not include C14. I DO NOT see a 47uF Electro cap that goes from +9V input to GND. The only components that are directly connected to the +9V input are C11, D1, R21, and R16. All of the layouts in the pdf EXCEPT FOR THE ONE YOU CAN PRINT OUT are correct. For some reason, the one that you use to transfer differs from the rest of them.

2) It appears that Q2 is effecting the input voltage to the quad op amp. I am not exactly sure how exactly   but it looks like it could be causing your low voltage readings at Pin 4 of the IC.

Hope this helps  

[Earthscum]

I have 2 boards that I made up for this after seeing a clip on youtube. After reading, alot of people are complaining that you have to push it hard to get the effect, in a jist. I keep forgetting to order the 10uF's so I don't deplete my stock on a single project.

Keep us up on how it goes... I'd like to populate at least one of these boards. If all goes well, probably use it on bass. It sounds like it should be pretty awesome, and appears that it should work fine with a bass (maybe change C2 and C7 to .22u at the most).

[Mark Hammer]

Mark,

Two things that I noticed after skimming the info:

1) It appears that the layout does not include C14. I DO NOT see a 47uF Electro cap that goes from +9V input to GND. The only components that are directly connected to the +9V input are C11, D1, R21, and R16. All of the layouts in the pdf EXCEPT FOR THE ONE YOU CAN PRINT OUT are correct. For some reason, the one that you use to transfer differs from the rest of them.

2) It appears that Q2 is effecting the input voltage to the quad op amp. I am not exactly sure how exactly   but it looks like it could be causing your low voltage readings at Pin 4 of the IC.

Hope this helps  

Thanks for reminding me about adding the 47uf cap.  I had made a mental note to do so, but I think that particular sticky blew away. (Post-its, real and mental, tend not to stick to dusty surfaces!)   I doubt that is affecting the voltage readings on the op-amp, though.

Apparengtly, the circuit can benefit from increasing the value of the gain pot, but that gain stage comes after the tunable filter section, so I suspect my difficulties with the circuit do not lie in the gain stage.  Once I get those things ironed out, I'll reassess whether the gain stage needs more oomph or not.

[Earthscum]

do you think it could benefit from a 10x increase in impedance in the filter section, like dropping the 10u's down to 1u and raising the corresponding resistances? That's the part of this that's really held me off on trying this out in  between projects. It just doesn't seem... Right.

[bean]

I don't know where my hand-made version is, but the manufactured version comes directly from that so I busted out the DMM for you. For V+ on the quad amp, I measure about 7.73v off an 8.89v supply. Some voltage drop is to be expected across D1 (and q2, I guess?). You can swap out D1 for a 1n5817. Even with all this, I'm not sure where the 4.6v is coming from unless you bridged to Vb somehow.

C14 was not present in the stock unit, but added for the fabbed board because there was room

Let me know if I can provide any more help. It's a terrific effect.

Looks like I used a TLC274 in my build now that I look at it.

[Mark Hammer]

Thanks.  That's useful info.  I can accept that some things will - and need to be - run off 4.5V (and less), but the idea of a Vref that would be half of that struck me as being unusual enough for an op-amp as to be unrealistic.

I have to haul out the bigger magnifying glass tonight and check for bridges that might have escaped my glance last night.

Damn Weller company!  My favourite soldering iron's tip has been eroded over the last 10 years, and they don't make tips to fit that chassis anymore.  Bought a Hakko with a nice fine tip that promptly died on me, so I went back to the blunt Weller, and the result would appear to be questionable joints. 

[Gordo]

I believe the C14 cap got dropped in Bean's latest revision.  I built up the earlier version SlapChop with no issues.  It sounds good.  Sort of a %^&*ed wah on steriods.

[Mark Hammer]

I found one solder bridge and removed it.  Hopefully, I'll troubleshoot all remaining obstacles between its current and desired state this evening.

[Derringer]

Thanks.  That's useful info.  I can accept that some things will - and need to be - run off 4.5V (and less), but the idea of a Vref that would be half of that struck me as being unusual enough for an op-amp as to be unrealistic.

I have to haul out the bigger magnifying glass tonight and check for bridges that might have escaped my glance last night.

Damn Weller company!  My favourite soldering iron's tip has been eroded over the last 10 years, and they don't make tips to fit that chassis anymore.  Bought a Hakko with a nice fine tip that promptly died on me, so I went back to the blunt Weller, and the result would appear to be questionable joints. 

which weller iron are you using?

[Mark Hammer]

It's about 25 years old, and the model number has long since worn off.  It's about a 25-30W model standalone model (i.e., not hardwired to a temperature-control stand) that uses tips with a sort of "lip" near the business end of the tip, and a screw-on collet to hold the tip in place.

[Derringer]

I have a generic weller that I bought from Home Depot which, as far as I could tell, has not specific replacement tips available. It has the screw on collet design (sort of like the insert screw on the knobs we put on out pots) and I took a chance on the ST tips (I like the st-7 for stompbox work) and they fit not quite as tightly as what came with the iron but tightly enough to do the job.

your iron is alot older than mine though so this probably isn't the case

[Mark Hammer]

Ha!!  Solved.

For reasons I cannot explain, a 1k resistor ended up in the R6 slot where a 27k resistor should have been.  The right value is in place and functions swimmingly now.

An interesting sort of booster that does give the "%^&*ed wah" sound.  I suggest to folks to swap out the 50k gain pot for a 100k and throw in a couple of back to back diodes in parallel with that gain pot as a switchable option.  Instant %^&*ed-wah overdrive tone.

[Gordo]

Now if you go back and listen to a LOT of Frank Zappa stuff you realize it wasn't always a wah pedal.  Especially the Pignose stuff.

[Mark Hammer]

Actually, if you stick the Frequency control in a footpedal, the unit makes a pretty decent wah. 

[Derringer]

i need to build one of these

I love zappa's tone

[Brymus]

Actually, if you stick the Frequency control in a footpedal, the unit makes a pretty decent wah. 

SOLD

[Mark Hammer]

Hell, stick ANY parametric equalizer section in a footpedal and it makes a great wah.  Legend has it that many producers would add wah in post-production by running the guitar track into a parametric section turning the boost up, setting the bandwidth just right, and working the frequency control manually.  The nice thing is that, where a wah acts in bandpass fashion and severely attenuates both lows and highs, a parametric section simply provides resonant accentuation without affecting content above and below.

...and if you want a kickass wah, increase the gain on that Systech with a 100k-250k Gain pot, throw a couple of diodes across that pot, mount the frequency control in a foot pedal, and away you go.  You'll probably want to swap that 1M output resistor for a 1meg volume pot if you're going to crank the gain.