6 ms·

Dissecting a Chinese Knockoff Guitar Pedal

81 points by cushychicken 11y ago

exabrial 11y ago
Haha... I have that _exact_ pedal on my board. Overall, not bad if you want something cheap... Couple of complaints: Things get muddy fast, you really have to pair it with a compressor to control your input volume for things to be any good. Next, there's a massive volume difference between the hot and warm modes. You can't flip between them without need to adjust the volume knob. Finally, there's a distinct lack of bass in the "hot" mode. Other than that, it's not terrible, just don't expect a ton and it's not too bad!
- mb_72 11y ago
  The kind of problems you've mentioned are typical of thoughtless "what a cool mod!" changes to a design; these often ignore practical issues such as the volume change you've mentioned. However, 'fixing' these issues would require a bit more work and a few more parts, attributes that seem commonly not to be important in low-end pedals. But, yeah, good for starting players (although even then I'd recommend a cheap multi-fx unit); beginners often don't even know what certain effects are, and once you know enough to feel you need a 'proper' version of effect you're better off getting something this is a step or two up from the cheapest available. (disclosure - part owner of Prophecysound Systems)
  - cushychicken 11y ago
    Yeah, I suppose if you wanted to do the extra bass mod right so that your volume level is mostly the same when going "hot", you'd also need to tweak the series resistor value as well to get the gain of the snubber to match up. Guessing you'd probably also want to drop down that parallel 470k as well.
- ricardobeat 11y ago
  Does the original have the same issues?
  - exabrial 11y ago
    Not exactly... It might be my hum buckers causing the muddy sounds well then volume gets too hot. I don't have a TS808 I can compare apples to apples with. The volume change problem and the lack of bass aren't problems for the TS808 because it was hardwired for the "warm" mode with no selector switch. Google is telling me the Boss BD2 doesn't have the toggle switch either.
  - cushychicken 11y ago
    Reduced gain in the lower frequencies is a feature, not a bug, of the original TS808 circuit. It was meant to keep the distortion from getting muddy. The original clipping stage includes a little resistor/capacitor snubber that rolls off frequencies below ~720Hz.
- ableal 11y ago
  > Next, there's a massive volume difference between the hot and warm modes. If I read the text and schematics correctly, that's because one uses 0.7V silicon diodes and the other 1.7V LEDs in the opamp feedback loop. (At least red LEDs used to be 1.7V when I was messing with them.) So that should clip the voltage in that branch to +/- 0.7 or +/- 1.7 volts, hence the power difference if nothing else is moderating it.
  - cushychicken 11y ago
    The turn on levels I measured were much smaller in discrepancy than that; the silicon diodes were clipping at 0.55 V, while the LEDs were only slightly higher, at about 0.8 V. Made me wonder if I was measuring them incorrectly.
    - ableal 11y ago
      That sounds OK, if a bit low. Perhaps the resistors are large, or you might be diverting some current through a low(ish) impedance voltmeter, but those should be rare nowadays. The trick with diodes is that the curve is exponential - so for a "0.7V" diode, and pulling numbers out of the air, you can get 0.3V for nanoamp currents, or 1.0V for power-station currents (for the brief moment before it melts ;-) The real equation is very simple, if anyone wants to play. For instance, it's well explained here, midway down the page: http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/ http://www.allaboutcircuits.com/textbook/semiconductors/chpt...
      - cushychicken 11y ago
        That's a good point; the DMM I used could have just been extrapolating "turnon" to a certain current. I'll have to check the DMM's specs.
userbinator 11y ago
The biggest unanswered question is how does it sound? You should resize the pictures before uploading - I was wondering why they took so long to download, and realised each one was >4MB! The full-resolution version is not that much clearer, they are 15MP but look as though there was a watercolour-like effect applied to them.
- Domenic_S 11y ago
  The telltale sign of a small sensor. A great example of how a larger file (in MPs) can look worse - taken on even a 10mp DSLR the pic would look substantially better. EXIF says it was taken by a Galaxy S5.
  - StavrosK 11y ago
    A small sensor and not enough light hitting it.
- cushychicken 11y ago
  Good question! I haven't had the chance to really let rip with the modified circuit yet, as I have a very noise-sensitive neighbor. The bass mod worked out pretty well for me, however. The stock version sounds like this, if you're curious: https://www.youtube.com/watch?v=cqPaL0vfVwU https://www.youtube.com/watch?v=cqPaL0vfVwU
Domenic_S 11y ago
My favorite part: > Just for completeness's sake, I included a quick ohm out of the [EOL] It's like an existential statement of some kind.
- cushychicken 11y ago
  That's what I get for pushing these out at half past midnight. Even thought it made for a really nice meta statement, I updated the post to finish my thought. Thanks for pointing it out. :)
valdiorn 11y ago
That actually looks really well made for a Chinese clone. I know the no-SMD and no-switches-on-the-board zealots won't agree, but the design is clean and solid. I was expecting a rats nest. Also, I used these sources for my work on a digital emulation of the device: http://www.geofex.com/article_folders/tstech/tsxtech.htm http://www.geofex.com/article_folders/tstech/tsxtech.htm http://www.bteaudio.com/articles/TSS/TSS.html http://www.bteaudio.com/articles/TSS/TSS.html
- cushychicken 11y ago
  Geofex was a huge inspiration for my first article on the TS808. Have you seen Electrosmash's rundown? That's some next level guitar pedal analysis. http://www.electrosmash.com/tube-screamer-analysis http://www.electrosmash.com/tube-screamer-analysis
dharma1 11y ago
Nice, hadn't heard of Donner before. I've got a bunch of chinese pedals (by Mooer, Joyo, Moen) based on Boss etc classic pedals of yesteryear - they have been solid performers so far. Wish the Chinese brands got into repro analog synths next :)
- jacquesm 11y ago
  > Nice, hadn't heard of Donner before. Mission completed.
- cushychicken 11y ago
  As it turns out, Joyo and Mooer are produced by the same company as Donner. I think the Joyo Tremolo is going to be my next subject for experimental surgery. https://www.geartree.com/p/joyo-jf-09-tremolo-effect-pedal-us-dealer?gclid=Cj0KEQiA7rmzBRDezri2r6bz1qYBEiQAg-YEtqcGxJKPWXR6tcOcGEO2nZDLJ59NPo4j0-s6Je8uS8caApCx8P8HAQ https://www.geartree.com/p/joyo-jf-09-tremolo-effect-pedal-u...
jacquesm 11y ago
This is an ad in disguise. First up the pitch: it's the same but much cheaper. Then the teardown and the continuous harping on how fantastic the quality is. Finally, an affiliate link to get you to go and buy it.
- cushychicken 11y ago
  Hey Jacques, author here. In a way, you're sort of right - I hacked the affiliate program a little bit, mostly to be compensated for my work in ripping apart the pedal and ohming out the PCB. But mostly, I wanted people to know that there's a cheaper alternative to "boutique" electronics that are sold at an outrageous markup. The fact that these are easy to modify is a plus. Also, I kind of liked the idea of showing off the workings of a Chinese product that's so clearly a ripoff of an American product. (Boss BD-2 Blues Driver, if you're curious.) Granted, that was also a ripoff of the TS808. And, I'll admit that something is lost in the spirit of the effort, since no one in China gets hung up when you take their design, improve it, and resell it. I appreciate the critique; thanks for reading - I'm a fan of your blog!
  - jacquesm 11y ago
    Maybe you could include a bit on what it actually sounds like, that would make it a lot more informative. It's not as if people buy these as sources for parts, they buy them to give them a specific sound.
    - cushychicken 11y ago
      That's the plan, once my noise-sensitive neighbor is gone for the weekend. :) Here's an example of what the stock one sounds like if you're curious. https://www.youtube.com/watch?v=cqPaL0vfVwU https://www.youtube.com/watch?v=cqPaL0vfVwU
      - jacquesm 11y ago
        The problem with promoting the product that you review is that your review skews towards the superlative approval. If you reviewed it without the affiliate link you might have added more balance to the article. That's a real risk when you're trying to make money of the things that you review and I don't know of a good way to both 'maximize your take' and 'be objective' at the same time. If I ever reviewed a product I would definitely not try to make money of that particular product.
noonespecial 11y ago
Should we even call these "knockoffs" anymore. By now, the tubescreamer circuit is practically mythological in guitar hacker circles. There are thousands of builds from one-off basement projects to commercial runs like this. It's more like a retelling of a favorite story.
creeble 11y ago
>...just some simple emitter followers with half-rail bias to maximize dynamic range of the buffer, and cap isolation to stop any nasty clicking or popping from circuit switching. Yeah, I don't think that's what the caps are for...
- cushychicken 11y ago
  On the input side? Absolutely! That 2.2M/330nF combo is a really low value highpass filter to keep any DC adjustment transients from a level mismatch out of the audio chain, which would result in one of those nasty loud "pops" you hear when you unplug a circuit. It's also serving to set the DC bias point of the input transistor without loading it down from the 2.2M pulldown.
  - creeble 11y ago
    On the latter part we agree.
    - cushychicken 11y ago
      Well, what am I missing here? Don't leave me in suspense! :)
johnatwork 11y ago
Is this one sold by Monoprice similar/same as well? https://www.monoprice.com/product?c_id=115&cp_id=11501&cs_id=1150108&p_id=611600&seq=1&format=2 https://www.monoprice.com/product?c_id=115&cp_id=11501&cs_id...
tomcam 11y ago
Weirdly, he does not compare its sound to that of the cloned pedal her refers to (Tube Screamer and its close relatives).

81 points by cushychicken 11y ago

Haha... I have that _exact_ pedal on my board. Overall, not bad if you want something cheap... Couple of complaints: Things get muddy fast, you really have to pair it with a compressor to control your input volume for things to be any good. Next, there's a massive volume difference between the hot and warm modes. You can't flip between them without need to adjust the volume knob. Finally, there's a distinct lack of bass in the "hot" mode. Other than that, it's not terrible, just don't expect a ton and it's not too bad!

mb_72 11y ago
The kind of problems you've mentioned are typical of thoughtless "what a cool mod!" changes to a design; these often ignore practical issues such as the volume change you've mentioned. However, 'fixing' these issues would require a bit more work and a few more parts, attributes that seem commonly not to be important in low-end pedals. But, yeah, good for starting players (although even then I'd recommend a cheap multi-fx unit); beginners often don't even know what certain effects are, and once you know enough to feel you need a 'proper' version of effect you're better off getting something this is a step or two up from the cheapest available. (disclosure - part owner of Prophecysound Systems)
- cushychicken 11y ago
  Yeah, I suppose if you wanted to do the extra bass mod right so that your volume level is mostly the same when going "hot", you'd also need to tweak the series resistor value as well to get the gain of the snubber to match up. Guessing you'd probably also want to drop down that parallel 470k as well.
ricardobeat 11y ago
Does the original have the same issues?
- exabrial 11y ago
  Not exactly... It might be my hum buckers causing the muddy sounds well then volume gets too hot. I don't have a TS808 I can compare apples to apples with. The volume change problem and the lack of bass aren't problems for the TS808 because it was hardwired for the "warm" mode with no selector switch. Google is telling me the Boss BD2 doesn't have the toggle switch either.
- cushychicken 11y ago
  Reduced gain in the lower frequencies is a feature, not a bug, of the original TS808 circuit. It was meant to keep the distortion from getting muddy. The original clipping stage includes a little resistor/capacitor snubber that rolls off frequencies below ~720Hz.
ableal 11y ago
> Next, there's a massive volume difference between the hot and warm modes. If I read the text and schematics correctly, that's because one uses 0.7V silicon diodes and the other 1.7V LEDs in the opamp feedback loop. (At least red LEDs used to be 1.7V when I was messing with them.) So that should clip the voltage in that branch to +/- 0.7 or +/- 1.7 volts, hence the power difference if nothing else is moderating it.
- cushychicken 11y ago
  The turn on levels I measured were much smaller in discrepancy than that; the silicon diodes were clipping at 0.55 V, while the LEDs were only slightly higher, at about 0.8 V. Made me wonder if I was measuring them incorrectly.
  - ableal 11y ago
    That sounds OK, if a bit low. Perhaps the resistors are large, or you might be diverting some current through a low(ish) impedance voltmeter, but those should be rare nowadays. The trick with diodes is that the curve is exponential - so for a "0.7V" diode, and pulling numbers out of the air, you can get 0.3V for nanoamp currents, or 1.0V for power-station currents (for the brief moment before it melts ;-) The real equation is very simple, if anyone wants to play. For instance, it's well explained here, midway down the page: http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/ http://www.allaboutcircuits.com/textbook/semiconductors/chpt...
    - cushychicken 11y ago
      That's a good point; the DMM I used could have just been extrapolating "turnon" to a certain current. I'll have to check the DMM's specs.

userbinator 11y ago

The biggest unanswered question is how does it sound? You should resize the pictures before uploading - I was wondering why they took so long to download, and realised each one was >4MB! The full-resolution version is not that much clearer, they are 15MP but look as though there was a watercolour-like effect applied to them.

Domenic_S 11y ago
The telltale sign of a small sensor. A great example of how a larger file (in MPs) can look worse - taken on even a 10mp DSLR the pic would look substantially better. EXIF says it was taken by a Galaxy S5.
- StavrosK 11y ago
  A small sensor and not enough light hitting it.
cushychicken 11y ago
Good question! I haven't had the chance to really let rip with the modified circuit yet, as I have a very noise-sensitive neighbor. The bass mod worked out pretty well for me, however. The stock version sounds like this, if you're curious: https://www.youtube.com/watch?v=cqPaL0vfVwU https://www.youtube.com/watch?v=cqPaL0vfVwU

Domenic_S 11y ago

My favorite part: > Just for completeness's sake, I included a quick ohm out of the [EOL] It's like an existential statement of some kind.

cushychicken 11y ago
That's what I get for pushing these out at half past midnight. Even thought it made for a really nice meta statement, I updated the post to finish my thought. Thanks for pointing it out. :)

valdiorn 11y ago

That actually looks really well made for a Chinese clone. I know the no-SMD and no-switches-on-the-board zealots won't agree, but the design is clean and solid. I was expecting a rats nest. Also, I used these sources for my work on a digital emulation of the device: http://www.geofex.com/article_folders/tstech/tsxtech.htm http://www.geofex.com/article_folders/tstech/tsxtech.htm http://www.bteaudio.com/articles/TSS/TSS.html http://www.bteaudio.com/articles/TSS/TSS.html

cushychicken 11y ago
Geofex was a huge inspiration for my first article on the TS808. Have you seen Electrosmash's rundown? That's some next level guitar pedal analysis. http://www.electrosmash.com/tube-screamer-analysis http://www.electrosmash.com/tube-screamer-analysis

dharma1 11y ago

Nice, hadn't heard of Donner before. I've got a bunch of chinese pedals (by Mooer, Joyo, Moen) based on Boss etc classic pedals of yesteryear - they have been solid performers so far. Wish the Chinese brands got into repro analog synths next :)

jacquesm 11y ago
> Nice, hadn't heard of Donner before. Mission completed.
cushychicken 11y ago
As it turns out, Joyo and Mooer are produced by the same company as Donner. I think the Joyo Tremolo is going to be my next subject for experimental surgery. https://www.geartree.com/p/joyo-jf-09-tremolo-effect-pedal-us-dealer?gclid=Cj0KEQiA7rmzBRDezri2r6bz1qYBEiQAg-YEtqcGxJKPWXR6tcOcGEO2nZDLJ59NPo4j0-s6Je8uS8caApCx8P8HAQ https://www.geartree.com/p/joyo-jf-09-tremolo-effect-pedal-u...

jacquesm 11y ago

This is an ad in disguise. First up the pitch: it's the same but much cheaper. Then the teardown and the continuous harping on how fantastic the quality is. Finally, an affiliate link to get you to go and buy it.

cushychicken 11y ago
Hey Jacques, author here. In a way, you're sort of right - I hacked the affiliate program a little bit, mostly to be compensated for my work in ripping apart the pedal and ohming out the PCB. But mostly, I wanted people to know that there's a cheaper alternative to "boutique" electronics that are sold at an outrageous markup. The fact that these are easy to modify is a plus. Also, I kind of liked the idea of showing off the workings of a Chinese product that's so clearly a ripoff of an American product. (Boss BD-2 Blues Driver, if you're curious.) Granted, that was also a ripoff of the TS808. And, I'll admit that something is lost in the spirit of the effort, since no one in China gets hung up when you take their design, improve it, and resell it. I appreciate the critique; thanks for reading - I'm a fan of your blog!
- jacquesm 11y ago
  Maybe you could include a bit on what it actually sounds like, that would make it a lot more informative. It's not as if people buy these as sources for parts, they buy them to give them a specific sound.
  - cushychicken 11y ago
    That's the plan, once my noise-sensitive neighbor is gone for the weekend. :) Here's an example of what the stock one sounds like if you're curious. https://www.youtube.com/watch?v=cqPaL0vfVwU https://www.youtube.com/watch?v=cqPaL0vfVwU
    - jacquesm 11y ago
      The problem with promoting the product that you review is that your review skews towards the superlative approval. If you reviewed it without the affiliate link you might have added more balance to the article. That's a real risk when you're trying to make money of the things that you review and I don't know of a good way to both 'maximize your take' and 'be objective' at the same time. If I ever reviewed a product I would definitely not try to make money of that particular product.

noonespecial 11y ago

Should we even call these "knockoffs" anymore. By now, the tubescreamer circuit is practically mythological in guitar hacker circles. There are thousands of builds from one-off basement projects to commercial runs like this. It's more like a retelling of a favorite story.

creeble 11y ago

>...just some simple emitter followers with half-rail bias to maximize dynamic range of the buffer, and cap isolation to stop any nasty clicking or popping from circuit switching. Yeah, I don't think that's what the caps are for...

cushychicken 11y ago
On the input side? Absolutely! That 2.2M/330nF combo is a really low value highpass filter to keep any DC adjustment transients from a level mismatch out of the audio chain, which would result in one of those nasty loud "pops" you hear when you unplug a circuit. It's also serving to set the DC bias point of the input transistor without loading it down from the 2.2M pulldown.
- creeble 11y ago
  On the latter part we agree.
  - cushychicken 11y ago
    Well, what am I missing here? Don't leave me in suspense! :)

johnatwork 11y ago

Is this one sold by Monoprice similar/same as well? https://www.monoprice.com/product?c_id=115&cp_id=11501&cs_id=1150108&p_id=611600&seq=1&format=2 https://www.monoprice.com/product?c_id=115&cp_id=11501&cs_id...

tomcam 11y ago

Weirdly, he does not compare its sound to that of the cloned pedal her refers to (Tube Screamer and its close relatives).