Having volume issues with my Tyrian Distortion

Hey all, just build my first pedals and the second one I put together was the Tyrian Distortion. When I play through it, I have to turn my amp up quite a bit more then I really should have to.. The tone sounds great, I get beautiful distortion out of it, and have no complaints on that end, which is what confuses me. I’m not sure what exactly would cause this sort of result when building. All values were double checked with volt meter before install, and after soldering in place just to be sure I didn’t mix anything up. I mean, the way I do my assembly is pretty fool proof as well, but the perfectionist in me still needs to double check things. Any help or suggestions on what might be causing this issue would be awesome. My other pedal pushes out at the same volume as it should, but this one when engaged is quieter then my clean channel when pedal is on bypass when it should be quite a bit louder with the volume pinned. If I need to pull the pedal apart to show the solder joints I can, but I’m pretty positive those are fine with my experience in soldering and how anal I am about it anyways 😂🤣😂🤣 I posted pics with this, but if more are needed just let me know please and I’ll pull it apart and get whatever photos/angles are needed !! Thank you all ahead of time for your help, couldn’t ask for a better forum then what I’ve seen from this one, it’s amazing how good of a group you guys have built here !! Thanks !!
 

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PJS

Active member
First part of troubleshooting is always make sure that your voltages are correct. If it is passing sound OK, then they probably are, but it's good practise to double check. Post the voltages on your IC pins here. Next step is to read up on how to build an audio probe if you haven't got one already, and use that to trace through the audio part of the circuit until you hear a volume drop.
 
Is the Output Jack tip clearing the Enclosure post, Maybe turn to same positon as Input Jack?
Turned the jack, no change, so it was close but still clearing, thanks for pointing it out either way, I didn’t even think about the corner of the enclosure getting that close to the base of the pin.
 
First part of troubleshooting is always make sure that your voltages are correct. If it is passing sound OK, then they probably are, but it's good practise to double check. Post the voltages on your IC pins here. Next step is to read up on how to build an audio probe if you haven't got one already, and use that to trace through the audio part of the circuit until you hear a volume drop.
All 4 chips are reading the same exact voltages, so I’m guessing those are correct. If you want me to post all the voltages I can, I just figured I’d ask since they were perfectly consistent between each one. Majority of pins right around 4.3, except for the lower left pin which read 0.3 on all 4 and the top right read around 8.7. So I think I’ll need to go the route of using an audio probe... I have no idea how to make one, I’ll have to look up a YouTube video or something to see what I can find unless you guys have a good way to make one that’s easy. It’d be a good tool to have I’m guessing so I’m glad I ran into this issue now so I can troubleshoot easier in the future that’s for sure. Also, once it’s made, how would I go about testing where the sound drops out ? I’m a bit of a noob when it comes to schematics and such, I mean I can figure out the gist of them, and know the basic physics of electronics and whatnot, but that’s going a little more in depth then I’m used to for sure, especially when I can’t see the route on the PCB physically.. well I guess I kinda can, just difficult with all the components so tightly spaced which is now seeming like a blessing and a curse haha !! 😂🤣
 

music6000

Well-known member
Try this first - Remove the Opamp's & re install them in different positions.

You could try the Pencil with Rubber type trick! (Something Non Conductive)
While you have some type of audio going through the pedal, Just press against all components one by one to see if there is a bad joint or connection.
 

PJS

Active member
When you find instructions on how to build an audio probe you will also find how to use it. Normally I would suggest starting at the beginning and working forwards. However, it sounds as if your problem is likely to be close to the output, so I think I would start there and work forwards. Start with the tip of the output jack, then back through the footswitch, and to the output pad on the PCB. Then the middle lug of the volume pot (volume here will vary with the knob position), R36, C28, IC3 pin 7, IC3 pin 5, R33, middle lug of mid pot, IC 3pin 1, IC3 pin 3, For now I would skip the tone section. If the problem is in there we can look at it in more detail. R22, C15, IC2 pin 1. IC2 pin 2, R20, IC 2 pin7. By that point you are deep into the part of the circuit that creates the distortion. As you say you are getting nice dirt I expect that you will have discovered a volume drop before this bit.
 
Welp, I put together an audio probe, but I don’t think I was using it correctly, I was trying but I must be tired or something because I’m just getting nowhere.. after I pulled everything apart and got feedback on the front and rear of every component I hoped that answered the question, but then after another look, I’m supposed to have my guitar hooked up to it the whole tome and having signal running through which I couldn’t get to happen, once I threw it back together, now it not performing the way it was, only makes a muffled sound when I hit strings hard.. oddly enough I didn’t really do anything other then clean up my PCB on the bottom a bit more and went through and touched the components, so I might have messed something up.. anyways, I’ll post a pic of my makeshift audio probe, I clamped the clip to the body of the pedal (the ground in most cases I thought, but probably incorrectly) then checked for feedback and volume drops on that feedback through all the components, obviously doing something wrong, I have found guides on building them, but then can’t wrap my head around the explanation of using them like I said, I’m gonna get some sleep and go at it with fresh eyes a little later, hopefully with some help from you guys pointing me in the right direction. Thank you PJS for giving me the layout to follow with the component numbers on the board. That’s a life saver and will make things much easier, if I need to change how my probe is or something, and if someone could explain hooking it up to probe components, I’d truly appreciate it. Thank you all for your help so far, it means a lot !!
 

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Oh and one more thing, just in case it happens to be the IC chips that might be bad, I have a full set of JRC4558 chips that I read are swappable for the ICs in the Tyrian pedal, and they are supposed to be for higher gain, where the TL chips in the Tyrian are for Mid gain (now I could have read this wrong so feel free to correct me) So, would it be possible to swap out the chips to test the other ones and see if that’s the issue ? I know they all output the same voltage when I checked them that way, I’m not sure if that’s the main way to check IC chips or not, so just thought I’d throw this idea out there too while I’m playing the troubleshoot game...
 
No, the first part of troubleshooting is thorough visual inspection. Check component values & orientation. Look for solder bridges, cold solder joints and debris. Use lots of magnification and light. Verify the pot values.
I went through and did that last night with a fine tooth comb, that’s one commonality I noticed when researching on here before I even got my pedals. I was concerned it was an incorrect pot value last night so I doubled checked that and it was all fine. So I think the audio probe is what I’m going to have to do, just have to figure out how to properly use it 😕
 

Chuck D. Bones

Well-known member
And you need to know what to expect when you probe different parts of the circuit. To keep the probe from loading the circuit, start by only probing pins 1 & 7 on the opamps. Use a looper to generate sound, or put a guitar with single-coil pickups close to the amp so it picks up hum.
Here is where I would check first:
IC2 pin 7. Should get pretty loud as GAIN is increased.
IC2 pin 1. Should be considerably louder than IC2 pin 7.
See if the LEDs (D6 & D7) light up at all.
 

twebb6778

Well-known member
Sounds like an incorrect component value, like using 100K when it should be 100R. But if you've already verified components your next step is to probe. Good luck!
 
Ok so got the audio probe figured out... now I tested my ic chips, 2 gets really loud as Chuck said, I don’t know if IC chip 4 is supposed to put any audio out but it is not... I went to the output, got the same low noise I was getting before.. now when I went from IC 3 pin 3 to R22 the sound jumped up to volume... so I’m not entirely sure if that identifies what’s wrong, I’m guessing if the order that PJS gave me is accurate for the single route, then it’s something right in that area... I’m gonna check the schematic myself and hope I’ll be able to find what’s going wrong.. if anyone can tell me what’s wrong based off what I just mentioned, I would really appreciate the assist.. thank you all for your help so far. I appreciate it !!
 
Also, R24 is loud on one side of the component and quiet on the other (if it matters, top is louder, bottom sounds like my main single problem noise, so that’s the first resistor that is different on each side following the schematic.. then R23 is louder on one side as well, but both are still much louder then the main single I’m getting.. so I think I’ve isolated the issue, but some direction would be nice so I’m not just pulling components and stuff when I don’t need to be..
 
UUUGGGHHH !!! I feel like I’m right there and I just can’t figure out how to fix it, this is driving me crazy !! Calling it quits for another night :-/ Hopefully tomorrow someone will be able to give me some insight on what might be going on.. I checked all my solder joints under my pots, I was getting an odd reading on R24 I believe (the 82k) so I re-soldered it and now I’m getting a solid reading of 82k, and no change so it might have just been the way I was holding my volt meter probe angling under the pots.. The same resistor is the one that has the loud noise out of one side, and low noise from the other side, not like booming loud, but definitely drops in volume... I don’t know if that’s normal for an 82k res so just thought I’d mention it. One other thing I noticed is that if I touch the center of any pot, the volume is it same, until I hit the B1M pot (gain) now that puts out at what I would assume is roughly full volume, not sure if that helps or not.. I was wondering, how do you know if a resistor is bad, or if it’s causing the issue ? Is it possible to bridge the pins from the underside and bypass it in a way ? Or would it still act like it’s supposed to because there bidirectional ?? I’ve followed the schematic to basically right at the end of the treble pot I believe, where R23 and R24 are located, and that is the point in which the volume starts to change within those few components. The problem being, now that I’ve located it, I’m pretty much at a loss on how to specifically identify the problem, and then correct it. I’m trying trial and error and just not coming up with any concrete solutions.. The audio probe I made is working beautifully, and I have my Digitech RP360 running the looper so I have constant sound and hear the changes between components when the pedal is engaged.. It still sounds perfectly fine when in bypass, the volume of the amp is not effected at all until the foot switch is pushed down, so hopefully I’ve give enough info to get some ideas from someone on getting this sucker going.. I have another batch of pedals getting here on Friday and would like to be able to start on those with this one working the way it should first so I’m not just pushing it to the side and not figuring out what went wrong in the event it happens again 😕
 

PJS

Active member
IC 4 is acting to stabilise the reference power supplies, so you are looking to get DC voltage out of it but absolutely no audio, so that is good. You will get some signal reduction through a resistor, so what you have noticed may be OK. Coupled with a capacitor you will also get a bit of filtering. The bit of the circuit that seems a bit suspect then would seem to be the network around the tone controls. Are the tone controls giving you the sort of variation in tone that you would expect?
 
IC 4 is acting to stabilise the reference power supplies, so you are looking to get DC voltage out of it but absolutely no audio, so that is good. You will get some signal reduction through a resistor, so what you have noticed may be OK. Coupled with a capacitor you will also get a bit of filtering. The bit of the circuit that seems a bit suspect then would seem to be the network around the tone controls. Are the tone controls giving you the sort of variation in tone that you would expect?
Yea. With the exception of the volume being so low when it comes out, I can adjust the tone and it makes changes like it should... see why I’m so confused on this whole thing, it’s just throwing me all off..
 

zgrav

Well-known member
using your audio probe, compare the sound levels at the middle leads on your bass, treble, and volume pots (max out the volume, and check minimum, mid and max positions on the tone controls). Are they all about the same volume?
 
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