Joyo JF-14 American Sound

[pingu]

but aren’t the caps in parallel
in this case ?

[sgosnell]

TBH, I'm not really sure. There are multiple ways of wiring a tone control. It's late, and I've had an adult beverage or two, so I'm not going to try to do the work on it right now.

[teeps]

I think the tone cap and the cable's capacitance are in parallel tho
I could be wrong ....

Both have one leg on signal an the other on ground, so: parallel. One of them (the tone ctrl) in series with a resistor and (both) in parallel with the inductance of the pu coil.

[charleyrich99]

I have the joyo American and on battery it is reasonably quiet. However, when I use it with an ac adapter, it produces a loud hum.

The same adapter works fine with other pedals. It is the correct 9v adapter with the correct polarity.

Does anyone have the same experience? Is my pedal defective?

-Charley

[sgosnell]

I doubt the pedal is defective. It's likely the power supply is defective. Some switching power supplies are very noisy. I have several that are unusable with any pedal, although some pedals are less sensitive to the noise than others.

[charleyrich99]

I doubt the pedal is defective. It's likely the power supply is defective. Some switching power supplies are very noisy. I have several that are unusable with any pedal, although some pedals are less sensitive to the noise than others.

Thanks. The power supply in question is quiet with other pedals. Can you recommend one you have used that is quiet with the Joyo?

[rpjazzguitar]

According to Chatgpt, if you put two caps in parallel the total capacitance is the sum of the two.

So, if you have a 20,000pf typical tone control cap in parallel with the 300pf capacitance of typical cable, the total is 20300. I think that means that if you dial the tone pot all the way down and it's wired to connect the cap to ground with no resistance in series, then you won't hear the capacitance of the cable.

OTOH, if you take the tone cap out of the circuit entirely, you would still have 300pf left from the cable. But what you're actually doing is putting a big resistance in series with it. This may have the same audible impact as removing the tone cap.

I wouldn't bet the farm that I'm right about this, but it seems to me that if you're already rolling off the tone cap part way, the capacitance of the cable probably won't be audible at all. The only difference is that the tone control might be rotated slightly to get the total capacitance where the player wants to hear it.

[sgosnell]

I don't even know the brands of the ones I have. They came with various devices over the years, I've never bought one just for use with pedals. One that seems to work well is actually a transformer, that plugs into a 5VDC power adapter and boosts the voltage to 9VDC. It's among the quietest I've found, and I have dozens of 5VDC chargers acquired over the years, included with all sorts of devices - phones, tablets, etc. I sometimes use it with 5VDC power banks (batteries), and those work well, and are silent. If I have to use an actual 9VDC adapter, I just go through the bag and try some. Some (most) are noisy, but I'm too lazy to mark them.

[sgosnell]

According to Chatgpt, if you put two caps in parallel the total capacitance is the sum of the two.

So, if you have a 20,000pf typical tone control cap in parallel with the 300pf capacitance of typical cable, the total is 20300. I think that means that if you dial the tone pot all the way down and it's wired to connect the cap to ground with no resistance in series, then you won't hear the capacitance of the cable.

OTOH, if you take the tone cap out of the circuit entirely, you would still have 300pf left from the cable. But what you're actually doing is putting a big resistance in series with it. This may have the same audible impact as removing the tone cap.

I wouldn't bet the farm that I'm right about this, but it seems to me that if you're already rolling off the tone cap part way, the capacitance of the cable probably won't be audible at all. The only difference is that the tone control might be rotated slightly to get the total capacitance where the player wants to hear it.

Calculating the capacitance of an RC circuit (which has both capacitors and resistors) makes my head hurt. But I'm not sure the total capacitance at the output jack, which is what counts, is the same as the tone capacitor, especially with two pickups. In any case, picofarads aren't large units. One trillionth of a farad.

[Spook410]

Thanks. The power supply in question is quiet with other pedals. Can you recommend one you have used that is quiet with the Joyo?

Had this problem with Voodoo power supplies. If you do a web search you'll find it's a common problem.

For a fix you can use a power supply that keeps the AC away from the board by using a power supply with an external transformer (wall wart) like MXR. Both of their models are compact and support quite a few high current pedals. I use them when I want a really light and small power supply. And while wall warts suck, they do keep noise away from your board. Then there is the Strymon Zuma which plugs directly into AC. Completely quiet with every pedal I've ever had close to it. Very nicely crafted. And kind of expensive for a power supply. Though honestly, it should last several decades so not sure how to equate value relative to the alternatives.

[garybaldy]

Had this problem with Voodoo power supplies. If you do a web search you'll find it's a common problem.

For a fix you can use a power supply that keeps the AC away from the board by using a power supply with an external transformer (wall wart) like MXR. Both of their models are compact and support quite a few high current pedals. I use them when I want a really light and small power supply. And while wall warts suck, they do keep noise away from your board. Then there is the Strymon Zuma which plugs directly into AC. Completely quiet with every pedal I've ever had close to it. Very nicely crafted. And kind of expensive for a power supply. Though honestly, it should last several decades so not sure how to equate value relative to the alternatives.

I have a 12vdc Peavey battery amp that runs on 8 x 1.5v D cells. It also has a 12vdc power socket.. I'm in the UK and have tried 2 new (different brands) wall warts - 240vac to 12vdc 2A.
Both are quite noisy. One was listed as a specific replacement unit for the amp (but not Peavey branded).
Any suggestions please? I don't have any other 12vdc equipment that I can test them on. Thanks

[Spook410]

I have a 12vdc Peavey battery amp that runs on 8 x 1.5v D cells. It also has a 12vdc power socket.. I'm in the UK and have tried 2 new (different brands) wall warts - 240vac to 12vdc 2A.
Both are quite noisy. One was listed as a specific replacement unit for the amp (but not Peavey branded).
Any suggestions please? I don't have any other 12vdc equipment that I can test them on. Thanks

Wish I could be more help. Assuming the way you stated this that the amp is quiet with batteries, noisy with wall warts. Really don't know but under the heading of 'any suggestions'..

Since the transformer is away from the amp, it's not going to be poor shielding. Not a ground loop as there is no third wire. Since both wall warts are noisy seems less likely it's the wall wart. Though some lesser chance it still could be. That leaves power input circuit on the amp or the source of AC you're plugging into. If the amp is quiet with the wall warts when plugged into a source of cleaner power like an inverter or when plugged in at another locale, then I would say it's your AC power. Though, it's possible the transformer in a wall wart filters AC power noise. Or not. Don't know. Maybe do a web search on that one. If it's noisy no matter where you plug in, probably at the amp.

[garybaldy]

Wish I could be more help. Assuming the way you stated this that the amp is quiet with batteries, noisy with wall warts. Really don't know but under the heading of 'any suggestions'..

Since the transformer is away from the amp, it's not going to be poor shielding. Not a ground loop as there is no third wire. Since both wall warts are noisy seems less likely it's the wall wart. Though some lesser chance it still could be. That leaves power input circuit on the amp or the source of AC you're plugging into. If the amp is quiet with the wall warts when plugged into a source of cleaner power like an inverter or when plugged in at another locale, then I would say it's your AC power. Though, it's possible the transformer in a wall wart filters AC power noise. Or not. Don't know. Maybe do a web search on that one. If it's noisy no matter where you plug in, probably at the amp.

Thanks. The amp is fine with batteries. When I can, I'd rather use a power supply but it's very frustrating. The problem is both at my home and where I rehearse. I guess, as you suggest, it's the amp. I'll take it to the guy that sorted a few dry joints in it when I first got it.
Ofcourse I could try one more wall wart!!

[sgosnell]

For batteries, I use rechargeable lithiums. The only use I have for regular alkaline 9V batteries is in smoke detectors. I also prefer using AC adapters, for convenience and economy, but it's hard to find a quiet one. As I said above, what I generally use is the converter cable that connects to standard 5VDC chargers. It's the quietest I've found. Something like this, although not that exact one. Mine is center positive, and I use a reversing cable that I made up to change it to center negative for use with pedals.

[garybaldy]

It does. I have a Line6 G10, an Xvive, and an Ammoon wireless, and they all boost about the same. I got a lot of interference with the Xvive because I have a router in the same room where I practice, and I bought the Ammoon 5GHz to try to avoid that, but they both have the connection affected. The G10 is rock-solid. It works as a preamp, as well as a DI box with both 1/4" and XLR outputs. It's more bulky for transporting, but it's a very reliable wireless DI system. The Xvive and Ammoon systems are fine if there is no strong transmitter of 2.4GHz or 5GHz signals nearby.

I'm awfully slow on the uptake. I've finally twigged as to why my once super clean Musicman 65RP seems to breakup with my regular setting that I've used for many years. Thought it was due to the recent repair and revalving but may be not. Think I'll have to try the lo gain input next gig.

[docsteve]

I think the noise issue is with the pedal and not with the power supply. I even bought a second American sound because mine made ugly noises with the power supply.

I think after I bought the second one, the first one stopped making those noises. Anyway, I haven’t used both of them in a long time so I can’t really remember the details.


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[KirkP]

I think the tone cap and the cable's capacitance are in parallel tho
I could be wrong ....

You are correct. If the tone pot on typical magnetic pickup equipped guitar is rolled all the way back, the tone cap will be in parallel with the much smaller cable capacitance, so cable capacitance should have a negligible effect. I doubt many guitarists roll the tone pot back quite that far, but maybe a few in the jazz community do.

I generally roll the volume pot back more than the tone pot, so I’d be more interested in whether cable capacitance has an audible effect when the tone pot is set to around 7 or 8. That’s a lot more complicated to determine, since it depends on the characteristics of the pickup. It’s not something I think much about though, since I can usually dial in a tone I like with any good quality cable.

[KirkP]

I have the joyo American and on battery it is reasonably quiet. However, when I use it with an ac adapter, it produces a loud hum.

The same adapter works fine with other pedals. It is the correct 9v adapter with the correct polarity.

Does anyone have the same experience? Is my pedal defective?

-Charley

I just did a quick test with my Joyo American Sound pedal into a solid state amp using a 1Spot power supply. I was using a single coil (non-humbucking) pickup and I was near some LED lights on a dimmer switch. There was very little hum (60 Hz or 120 Hz) or LED/dimmer buzz, and virtually no change running off the battery vs the 1Spot.

I don’t have enough info to diagnose your issue, but I’d suspect either a poorly filtered power supply or a bad ground somewhere. Is what you hear a low frequency hum, or is it the high frequency buzz one often gets from LEDs, dimmers, video monitors, computers, and poorly filtered wall warts?

I’ve had the Joyo for a few years, but didn’t use it much until a few months ago. Now I use it most of the time. I start with the level near max, the drive near min, and all EQ controls flat, then tweak things a bit depending on the room, what instruments are in the band, etc. Small adjustments to the the Voice and Drive pots make it easy to dial in something pleasing. I wish I had something like that long ago. The Voice circuit is basically a mids control ahead of the clipping circuit. It’s nearly the functional equivalent of the Tech21 Blonde, though not a detailed copy of the circuit.

[nevershouldhavesoldit]

One that seems to work well is actually a transformer, that plugs into a 5VDC power adapter and boosts the voltage to 9VDC. It's among the quietest I've found, and I have dozens of 5VDC chargers acquired over the years, included with all sorts of devices - phones, tablets, etc..

I don’t understand what you’re describing. There is no such thing as a DC transformer. Transformers work because AC in the primary winding induces AC in the secondary winding, with the ratio of turns between them determining the ratio of output to input voltage.

[sgosnell]

https://www.amazon.com/current-Negative-Connector-compatible-effects/dp/B07GD54Q66

The link didn't get included in the previous post, my fault I suppose.