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Hi guys, this is my first post as I’m new to the pedal building/assembling world and have not yet needed to ask for help like this, however I’m as desperate as they get.
The issue I’m having is to do with my Ratt deluxe. When I rotate the gain pot there is a particular audible frequency poking out, so to speak. It sounds a little like a wah as you turn the knob, or like a phaser or flanger being manually controlled (I hope I’m making sense). Starting at full clockwise and turning counter clockwise, the pitch of the frequency goes from very low to very mid peaked to super high pitched to the point of barely being audible. The frequency is also audible whilst playing guitar, and gives the pedal a nasaly tone that I can’t stand.
This has now happened on both Ratt builds, with the only components used between both builds being the OP07 chip, the 3 pots, the 2 switches and the 2N5485 transistor (I’m currently waiting for a 2N5459 to arrive so I can try that). Included is the schematic and photos of my current build.
So far I have tried other transistors to no change, I’ve tried swapping the gain pot for a fresh one to no change as well, I’ve tried a TL071 chip to no effect and I’ve messed around with some of the components connected to the gain pot which produced no change.
I really love the sounds of this pedal and I’ve literally lost sleep over this issue so if I could please get some help I would genuinely be eternally grateful.
Hi, I’m not one of the gurus here but I’ll try to help. Judging by the pictures you are bench testing your build.
If you are bench testing, be sure you have all the ground connections complete between the board, jacks and power supply, as per the build doc. A second note about bench testing is that enclosures shield the board from noise as well.
hi, another ammature builder here. i just finished one of these and it is generally a hi gain box. there’s gonna be some buz at the high extreme of the gain knob. i also second the opinion that it will be noisier out of the box. also, the power source can be a source of radio interference, you might try a 9v battery to isolate.
Thanks for replying and offering some help guys, any bit of advice or suggestion is helpful and I appreciate it.
Yes I am at the bench testing stage for this current Ratt build (my 2nd Ratt board), but I had the exact same issue with the previous Ratt (1st Ratt board) while it was in its enclosure so I don’t think that is the issue. I’ll put it in an enclosure today and see if it changes anything this time.
I’ll have an update in a few hours (gotta get through the work day first)
I’ll also try get a video/audio of the issue so you can have a better understanding of what it is
I just wired up a battery connection to the circuit and the frequency was still present so we can rule out a power supply issue.
So far, I’ve tried:
Swapping the IC (to LM741 and TL071)
Changing the transistor (however, they weren’t transistors recommended anywhere by anyone so I doubt this ruled out anything, not at least until I try the 2N5459 that are on their way to me). This only resulted in the circuit sounding like a crappy mis-biased fuzz.
I’ve used different resistors, capacitors and diodes.
I’ve swapped the A500k gain pot to a new one.
And now wiring a battery connection.
This first video is of the first Ratt build I did. It’s in its enclosure and wired so the boost is before the rat.
https://www.youtube.com/shorts/lBVFXWoVqs4
This second video is of the one I’m currently dealing with, in the video it is hooked up to a footswitch test box that has work perfectly with multiple other builds.
https://www.youtube.com/watch?v=EKjGyAmkbB8
I’m praying to god this videos give you guys some more context/insight, I’d LOVE to get this pedal going. I’ve even seen 2 or 3 other people posting their successful builds and it’s killing me.
I’m totally clueless as to what could be causing this on 2 separate builds, the only thing I can think of would be the transistor (or the IC but I’ve checked this and it solved nothing) since besides the pots and the IC it’s the only component that the two builds have in common.
I’m almost at the point of buying a whole new kit, yet again, to try get a normal functioning Ratt Dlx.
I’d personally reflow any solder joints that look dull, grey, ball like or crumbly
It could be a few things causing the noise in the 2nd video, even something as simple as a dry solder joint especially on a capacitor or cross talk from audio wires running in paralell or too close to power wires a poor ground connection etc
Visually inspect your solder joints under magnification making sure there’s a good solder connection between component pin and solder pad
The FET is a unity gain amp / buffer the 5485 would be ok that’s not to say it wouldn’t cause it, especially if it’s fake where did you get it
You can also use the non technical method of touching or wiggling with a non conductive item like a plastic pen to see if it affects the noise or dab your finger on and off solder joints this may help narrow down your problem area
You obviously need to try and keep the pcb from moving whilst you do it
Make sure your transistor is fully in it’s socket
You can also touch the transistor with your finger to see if it affects it.
It would seem that you would have to do the same thing twice to get the same result between two builds. Try something different. Consider using some sockets and populating C3. Start with a 22p and work up. If the extra cap doesn’t fix anything just take it out, no harm no foul.
I’ll go through and inspect and touch up all joints and report back, thank you.
In regards to where I bought the 5485, it was from pedapartsaustralia.com so I’d hedge my bets on them being legit but I’m not sure. And I’m certain the transistor is fully seated in the socket(s).
In regards to the cap at C3, I had it populated with a 22p in the first build (first video) and the sound was still present, and I removed it to see if anything changed and unfortunately it didn’t do anything. Having said that, I will populate it on the current build and see what happens.
Thanks guys, I’ll give your suggestions a go and report back.
Please go back re-read the build document carefully. If you follow that doc to the letter, you will find success. Using a TL071 instead of an LM308 or OP07 might be a problem. The second issue is that R7 AND the trimpot are both in place. Can’t tell what value trimpot you have in there. (Again, that bit is in the build doc.)
And please double & triple-check ALL the grounds.
The photos did not show a ground wire attached to the main GND pads.
The section of the build doc talking about the Ruetz mod (trimpot and R7) confused me a little, I think that is evident lol. I currently have a 1k trimpot installed with 100R resistor socketed in R7, however it says on the build doc that doing just that will yield the desired results. Am I misinterpreting that still?
In regards to the TL071 being a potential issue; I’m fairly confident it is compatible based on some reading on a few forums, plus I’ve seen posts on this forum with TL071’s being used in the same circuit.
UPDATE: The problem has been rectified. Cybercow, thank you so very much for your simple and most of all obvious suggestion. I resoldered everything, connected the main grounds but most importantly, and the actual solution, was removing the trimpot I had installed, cleaning out the holes and putting in a 120R into the sockets at R7.
The annoying thing is that I had tried this when the issue first presented itself on the first build attempt but I didn’t clean out the holes. So I could’ve saved myself many many hours of stress, anxiety and headache and many hours of effort if I had been more thorough with my soldering, cleaning and reading of the build doc. This has been an experience and I’ve certainly learnt a LOT.
Thank you to all who contributed suggestions, I really appreciate it but especially thank you to Cybercow.
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