hey everyone, long time lurker, first time poster, so sorry if this is in the wrong forum section. i've got a project that i've run into some issues with that i'm pulling my hair out trying to figure out what's wrong and hoping someone more experienced may have an idea of what's happening. so excuse the long post, trying to give as much detail as i can.
so long story short i decided to make a mini solid state guitar amp using a 100watt TPA3116 mono amp board that i snagged on ebay.
i put a jfet preamp in front of it that i created from the 1st gen sunn model t, and i'm powering it with 24VDC using a 4A to 6A 24V switching power supply board i also grabbed from ebay as well.
now for the problem. i'm not getting any signal output other than a rhythmic ticking approx 1 per second, if anything is connected to the input or not. i checked the power output from the power board and i'm getting a consistent 23.81VDC, the light on the power board is red (not sure if it should be green or if it's bicolored), and the same voltage at the amp and preamp. i used an audio probe from the input to the amp and there's good clear signal all the way up to the amp input, after that no idea. i also wired in a TPA3118 60watt amp in place of the 100 watt to check to see if the amp is a problem, but same thing happens. i was thinking i had an issue was positive voltage going through the output and there's a small change from 0V to .1V when the tick occurs.
on the amp board i've got the positive and negative wires from the power supply connected properly, the output negative is connected to the ground lug of the mono jack & positive is connected to the other lug going to the tip. the output from the preamp is a single wire, which is connected to the positive pad of the amp board, the negative and ground are empty, as is the mute. All grounds go to either the ground of the input or output jacks.
in my head it's got to be either something with the power board, or the way i've got the amp hooked up. i'm completely stumped since the signal is good in the preamp. thanks for any help in advance and thanks for all the info i've gotten over the years on the forum.
so long story short i decided to make a mini solid state guitar amp using a 100watt TPA3116 mono amp board that i snagged on ebay.
i put a jfet preamp in front of it that i created from the 1st gen sunn model t, and i'm powering it with 24VDC using a 4A to 6A 24V switching power supply board i also grabbed from ebay as well.
now for the problem. i'm not getting any signal output other than a rhythmic ticking approx 1 per second, if anything is connected to the input or not. i checked the power output from the power board and i'm getting a consistent 23.81VDC, the light on the power board is red (not sure if it should be green or if it's bicolored), and the same voltage at the amp and preamp. i used an audio probe from the input to the amp and there's good clear signal all the way up to the amp input, after that no idea. i also wired in a TPA3118 60watt amp in place of the 100 watt to check to see if the amp is a problem, but same thing happens. i was thinking i had an issue was positive voltage going through the output and there's a small change from 0V to .1V when the tick occurs.
on the amp board i've got the positive and negative wires from the power supply connected properly, the output negative is connected to the ground lug of the mono jack & positive is connected to the other lug going to the tip. the output from the preamp is a single wire, which is connected to the positive pad of the amp board, the negative and ground are empty, as is the mute. All grounds go to either the ground of the input or output jacks.
in my head it's got to be either something with the power board, or the way i've got the amp hooked up. i'm completely stumped since the signal is good in the preamp. thanks for any help in advance and thanks for all the info i've gotten over the years on the forum.
With the preamp disconnected it still ticks. Not sure what you mean by where does the ground return go from the amp to preamp. Do you mean the ground pad on the amp next to the positive pad? If so i don't have any wire connected, but it is tied to the chassis through the board and I get continuity with the chassis. If you're talking about the ground for the preamp it's attached to the input jack ground lug.
Opps, that should be it. The board is configured as at BTL. That means both speaker terminals is "floating" at half VDD (about 12V in your case). There is no ground for the output signal.
Connect negative (black) output terminal to the - on the board and positive (red) to the + on the same blue post.
An amplifier has to use a balanced power supply (+ 0 -) to have en unbalanced output.
Connect negative (black) output terminal to the - on the board and positive (red) to the + on the same blue post.
An amplifier has to use a balanced power supply (+ 0 -) to have en unbalanced output.
Awesome. I knew it was something silly. First time using one of these, so it's a bit of a learning curve. When you say connect the negative output terminal to the - & + on the board you're talking about the on the power terminals? I can't picture it for some reason? Btw, I checked a buddy's build of one that was just the amp and he used closed jacks, where I used open jacks, and he connected the ground for the board to the ground on the output jadck which isn't tied to the chassis. If I switched to the closed jacks and did that will that solve the problem too?
Should have noticed that. As soon as I saw voltage mentioned my brain went right to the power section. So basically just jumper the - & + terminals of the speaker output? Would switching to closed jacks and doing what my buddy did work as well?
You connect +/- PCB power termials to +/- terminals of your DC supply.
Connect +/- PCB speaker terminals to your speaker terminals.
Connect input to input terminals where input- should be internally connected to -DC-Power terminal.
I do not understand the implications of "closed jacks" to be honest.
I suggest that if you power your module with speaker terminals not connected the clicking/blinking diode is gone.
Which would be a strong indication for wrong wiring of the speaker terminals
It might be helpful to read the manual and follow the wiring scheme.
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sorry for not replying sooner. the board didn't come with a manual, but i did read through the datsheet for the TPA3116 chip. by read i mean skimmed, which is my fault.
so here's the update. i fixed it really quickly and easily, thanks to you guys. i ended up ordering some different jacks for the output to isolate it from grounding to the chassis, and they came yesterday.
i was using these open style neutrik jacks for the output
which grounds the sleeve, and switched to the closed style wish has the sleeve isolated from ground.
so once i removed the - lead from the amp board speaker out from ground, and attached it to the sleeve lug of the isolated enclosed jack she fired right up and worked perfectly.
i'll tell you something, i'm really impressed with this little 100watt TPA3116 power amp. it's loud and clean, well at least as clean as it should be with the model t preamp in front of it. honestly, damn thing sounds like the tube amp with some subtle differences in distortion since you don't get the even order harmonics that you get from tube distortion.
now i just have to figure out how to wire the damn #47 pilot light bulb, since it's not going to be wired like a tube amp with +6.3V to both tabs of the socket like it gets from the transformer in a tube amp. might just run an LED under the jewel to get the same effect and no have to deal with an incandescent bulb.
thanks guys for the help.
so here's the update. i fixed it really quickly and easily, thanks to you guys. i ended up ordering some different jacks for the output to isolate it from grounding to the chassis, and they came yesterday.
i was using these open style neutrik jacks for the output
which grounds the sleeve, and switched to the closed style wish has the sleeve isolated from ground.
so once i removed the - lead from the amp board speaker out from ground, and attached it to the sleeve lug of the isolated enclosed jack she fired right up and worked perfectly.
i'll tell you something, i'm really impressed with this little 100watt TPA3116 power amp. it's loud and clean, well at least as clean as it should be with the model t preamp in front of it. honestly, damn thing sounds like the tube amp with some subtle differences in distortion since you don't get the even order harmonics that you get from tube distortion.
now i just have to figure out how to wire the damn #47 pilot light bulb, since it's not going to be wired like a tube amp with +6.3V to both tabs of the socket like it gets from the transformer in a tube amp. might just run an LED under the jewel to get the same effect and no have to deal with an incandescent bulb.
thanks guys for the help.
In this case I don't think that was the issue. The problem was because of the improper wiring of the speaker out, specifically because I had the - lead from the speaker out connected to ground. After the switch of the output jack and correcting the wiring for the speaker out the tick is gone, and everything works perfectly.
@rocket88 How does you amp sound? What kind of speaker/cabinet are you powering with it?
How loud does it play?
sounds pretty badass if i do say so myself. pretty damn close to a tube gen 1 model t. the power amp puts out 100watts at 4ohm and like 70-80watt at 8ohm, so output is good enough for practice and gigging, especially if you're being miced and run through the house pa. i've played it through both my apeg micro svt 2x10 8ohm cab, and my mesa boogie powerhouse 4x10 bass cab. it's significantly louder with the 4x10, which makes sense since there's more air being pushed than with the 2x10. i do plan on building 4x12 guitar cabinet that's switchable from 4ohm to 8ohm as i plan on making a few guitar tube amps so i want a guitar cab.
here's a shot clip i made with it playing the opening riff to Electric Wizard's Funeralopolis. gain for both channels at noon so slightly dirty, master volume is at about 2 o'clock if i remember correctly. i kicked on a pedal i make called the Cosmic Owl started as an original Ross Distortion, but heavily modified for more low end, and an active Bandaxall tone stack. i recorded it with my iphone mic, so you don't get 100% how massive it sounds, but you could feel it running through you even with the tiny 2x10.
Thanks a lot for this information! I'm going to make a small amp for my acoustic guitar. I think I'll stick with a stereo board but that I'll run in PBTL mode through either a single 4ohms speaker (rescued from a dead studio monitor) or a pair of 8 ohms Pioneer bookshelf speakers (I'll wire them in parallel to get a final impedance of 4ohms).
I don't need a lot of power, I just need to have a clean acoustic sound while hearing myself clearly at gigs (the drummer is usually just behind me).
Do you have a picture of your finished amp?
I don't need a lot of power, I just need to have a clean acoustic sound while hearing myself clearly at gigs (the drummer is usually just behind me).
Do you have a picture of your finished amp?
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