Thanks for the advices Turbowatch2,
As you may guess i have basically zero knowledge and practice in high current/voltage handling... I have some basics of theoretical notions from my master's degree in biology but really it is not that much. I wanted to learn with practical stuff as i usually do when i know nothing on a subject ^^
I'm in france so basically, the yellow wire is ground. I don't know how ground works with all that stuff (metal case, wooden/plastic case, SMPS or not,...).
So i'll try to remove this ground wire on the SMPS as you said, to see if that improve something, and also put the gray wire from the pot to the amp boards ground.
At the end, if it doesn't work, maybe it would be better to stop experiment with high current /voltage stuff without a minimal education (books or something, maybe can you advice me for a good book to begin with ?).
I found a DELL 19.5V / 6.7A (or even a 20V / 8.5 A) laptop power supply (I heard it is perfect), I may be better to use it instead of what I have done.
Overall I thanks you very much for your help
For my final build, it will just be the amp in its acrylic case positionned not so far the bookshelf speakers (Wharfedale diamond 9.1) and powered by the best source i can find.
As you may guess i have basically zero knowledge and practice in high current/voltage handling... I have some basics of theoretical notions from my master's degree in biology but really it is not that much. I wanted to learn with practical stuff as i usually do when i know nothing on a subject ^^
I'm in france so basically, the yellow wire is ground. I don't know how ground works with all that stuff (metal case, wooden/plastic case, SMPS or not,...).
So i'll try to remove this ground wire on the SMPS as you said, to see if that improve something, and also put the gray wire from the pot to the amp boards ground.
At the end, if it doesn't work, maybe it would be better to stop experiment with high current /voltage stuff without a minimal education (books or something, maybe can you advice me for a good book to begin with ?).
I found a DELL 19.5V / 6.7A (or even a 20V / 8.5 A) laptop power supply (I heard it is perfect), I may be better to use it instead of what I have done.
Overall I thanks you very much for your help
For my final build, it will just be the amp in its acrylic case positionned not so far the bookshelf speakers (Wharfedale diamond 9.1) and powered by the best source i can find.
Hello,
I never used this amp (Allo Volt+ with stepped attenuator) but i have read a lot of good things on these, these are well built amplifier but a bit in the expansive side IMHO.
By the way it is a TPA3118 chip on this board.
I allow myself to update my journey
- tried to disconnect the yellow cable (ground) and it didn't improve anything (gave up)
- tried my Dell 19.5V / 6.7A and it sounds good, i'll continue with that for the power supply
- i want to reduce the gain on my board from 26dB to 20dB: i have to play with the R18 (100K)/R19 (20K) values (which corresponds respectively to R2 and R1 in the TPA3116D2 datasheet)
Can i just remove R18 (R2), let it open to modify the gain settings or do i need to also change the R19 (R1) value to 5.6kOhms ?
Also i would like to mod the board to improve it :
- Anti-plop system, a very well known mod but I can't find any ressources that allow me to do it on the same layout as my board, can you help me to design it ?
- I heard about something like "bootstrap snubber mod", i don't know what it does (reduces noise ?) maybe can you tell me more about this please ?
- last but not least, i have couples of audiophiles capacitors (Nichicon BP, FW, KA, Wima caps,...) is it worth to changes the capacitors on the boards ? And what do you recommend ?
i can change 8 * 470µF 50V electrolytic capacitors (in same values ? Nichicon FW)
8 * 220µF 35V capacitors (in same values ? Nichicon BP)
6 * 0.68µF (yellow caps) (in same values ? Wima MKP2 or MKS2)
Thanks for the help,
Papaya
I never used this amp (Allo Volt+ with stepped attenuator) but i have read a lot of good things on these, these are well built amplifier but a bit in the expansive side IMHO.
By the way it is a TPA3118 chip on this board.
I allow myself to update my journey
- tried to disconnect the yellow cable (ground) and it didn't improve anything (gave up)
- tried my Dell 19.5V / 6.7A and it sounds good, i'll continue with that for the power supply
- i want to reduce the gain on my board from 26dB to 20dB: i have to play with the R18 (100K)/R19 (20K) values (which corresponds respectively to R2 and R1 in the TPA3116D2 datasheet)
Can i just remove R18 (R2), let it open to modify the gain settings or do i need to also change the R19 (R1) value to 5.6kOhms ?
Also i would like to mod the board to improve it :
- Anti-plop system, a very well known mod but I can't find any ressources that allow me to do it on the same layout as my board, can you help me to design it ?
- I heard about something like "bootstrap snubber mod", i don't know what it does (reduces noise ?) maybe can you tell me more about this please ?
- last but not least, i have couples of audiophiles capacitors (Nichicon BP, FW, KA, Wima caps,...) is it worth to changes the capacitors on the boards ? And what do you recommend ?
i can change 8 * 470µF 50V electrolytic capacitors (in same values ? Nichicon FW)
8 * 220µF 35V capacitors (in same values ? Nichicon BP)
6 * 0.68µF (yellow caps) (in same values ? Wima MKP2 or MKS2)
Thanks for the help,
Papaya
- i want to reduce the gain on my board from 26dB to 20dB: i have to play with the R18 (100K)/R19 (20K) values (which corresponds respectively to R2 and R1 in the TPA3116D2 datasheet)
Can i just remove R18 (R2), let it open to modify the gain settings or do i need to also change the R19 (R1) value to 5.6kOhms ?
Papaya
Removing R18 should be sufficient.
If you anyway have the capacitors, I would try replacing them.
"Bootstrap snubber"?? The bootstrap principle is used to increase input impedance or generate a higher operating voltage for the drive circuit. A snubber serves to absorb smaller amounts of energy, typically from second order parasitic effects. "Bootstrap-snubber", a miracle circuit?
"Anti-plop" circuit, I need to study the datasheet.
Biology - fine. When we use organic superconductors, you will be teaching us.
For once it is us down south having the warmest weather.
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Hello, i am using this amp Bluetooth 4.2 TPA3116D2 Subwoofer Audio Amplifier Board 2.1 2*50W+100W DC12-24V | eBay
I get a really noticeable bazzing sound from the speakers whenever i connect it to my computer via 3.5mm cable. If i connect it with the same cable to my smartphone or laptop its almost silent, i still get a light hissing though. It makes the buzzign sound both in the front pannel headphone output and in the I/O output of the motherboard (200 ohm output impedance) or even in my monitor's 3.5mm jack. I tried different cables (thought none of them is shielded) and nothing changed. If i use it with Bluetooth it doesn't make any buzzing sound.Also the volume of the buzzing is attenuated by the amp's tone knob, if i turn it down the buzzing get louder if i turn it waay up it almost completely stops, i guess this says soemthign abotu the buzzing's frequency? At the moment the amp is not in some enclosure but i dont think thats the problem with my case. The power supply i use is a 24v laptop power supply. More over none of my previous 2.1 systems had any similar problem and they where very low quality so its probably not the computer's problem either. I am guessing it peaks electromagnetic interference from the surrounding electronics and because the output is stronger than the smartphone's the buzzing is more noticeable. will a better shielded cable fix this?Do i need a DAC to get rid any interference?
I get a really noticeable bazzing sound from the speakers whenever i connect it to my computer via 3.5mm cable. If i connect it with the same cable to my smartphone or laptop its almost silent, i still get a light hissing though. It makes the buzzign sound both in the front pannel headphone output and in the I/O output of the motherboard (200 ohm output impedance) or even in my monitor's 3.5mm jack. I tried different cables (thought none of them is shielded) and nothing changed. If i use it with Bluetooth it doesn't make any buzzing sound.Also the volume of the buzzing is attenuated by the amp's tone knob, if i turn it down the buzzing get louder if i turn it waay up it almost completely stops, i guess this says soemthign abotu the buzzing's frequency? At the moment the amp is not in some enclosure but i dont think thats the problem with my case. The power supply i use is a 24v laptop power supply. More over none of my previous 2.1 systems had any similar problem and they where very low quality so its probably not the computer's problem either. I am guessing it peaks electromagnetic interference from the surrounding electronics and because the output is stronger than the smartphone's the buzzing is more noticeable. will a better shielded cable fix this?Do i need a DAC to get rid any interference?
Hi Kyrk,
There are important differences between buzzing (hum / net frequency related noise) and hiss (broad-band almost white noise spectrum noise) and their reasons are different. I will deal with buzzing/hum.
Even experienced DIYers can start sweating when they have to solve ground-loop issues. Ground-loop issues vary with every setup such that we cannot just point at a generic solution.
Ground loops often relate to more power supplies in the same signal chain. PC type computers in the signal chain often cause problems.
To find out what (minimum) level you can arrive at, you remove all other signal cables than a cable going to the headphone output of your smart-phone. Let the smartphone play (without charger) but with the volume on the phone turned fully down. The buzzing you have in the speakers with the amplifier volume turned up shows what the amplifier alone can do. With the volume of the amplifier turned up, you often hear a little buzzing (coming from the power supply or radiated from other appliances in the room).
To find out what causes the buzz you have with the full signal path in place, you use a method where you "work your way backwards" through the signal chain.
Working your way backwards in steps:
* All signal cables to the amplifier disconnected. The active input connectors short-circuited. Any important buzz? Remove the short-circuits from the active inputs.
* Connect a signal cable to the amplifier input you most often use. Make sure that the cable ground is well connected to the amplifier. Short-circuit the signal cable in the end away from the amplifier. Any important buzz? Remove the short-circuits from the cable inputs.
* Connect your pre-amp/DAC/PC to the signal cable but do not connect the pre-amp/DAC/PC to power. Any important buzz?
* Connect pre-amp/DAC/PC to power but do not turn the power ON yet. Any important buzz?
* Turn the power to the pre-amp/DAC/PC ON. If you use a pre-amp, short-circuit the inputs. Any important buzz? Remove short-circuits from the pre-amp inputs.
* Connect a source to the pre-amp or a computer to the DAC. No connection to power yet. Any important buzz?
* Connect the source or computer to power but do not turn the power ON. Any important buzz?
*Turn the power to the source or computer ON. Any important buzz?
If there is a buzzing problem, the buzz should appear during one of the steps above.
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Hey Faux
I followed the steps and here is what i found:
With the pc connected to the amp with a 3.5mm cable i can hear buzzing when the pc is on and when i shut it down but it's power supply switch is on and its connected to the wall plug. If i leave it connected to the wall and turn it off by it's psu switch the buzzing continuous but at a lower volume and if i unplug the computer from the wall the buzzing disappears. Notice that the amp is using it's own powersupply and its not gatting any power by the computer. Does that mean that the buzzing is coming from the pc psu? If so, why am i not getting any buzzzing when i connect to it cheap commercial 2.1 systems?
Good work! The combination of a PC power supply and a (separate) amplifier power supply often gives hum.
If you can and your power plug for the amplifier is a plug without earth connection (flat type), try to turn the amplifier power plug 180 degrees around when you connect it to the net. Any difference? The reason for this weird suggestion is that a PC uses an SMPS. Your amplifier may also use an SMPS. SMPS normally have a safety-capacitor between primary return and secondary (for EMI reasons I suppose). If your two power plugs (PC and amplifier) are connected such that the primary return of the two SMPS are in phase, little current will run through the safety capacitors. If they are connected in counter-phase, more current will run through the safety capacitors and in the ground wire.
If that does not help, we have to think of a way to break the galvanic connection between the PC and amplifier.
Hi all, has anyone listened to the sound of this amp?
Why are outputs next to the input attenuator and the input wires (nonshielded) routed along the output cables to the other side? IMO the case was designed for the board in the opposite direction.
The plugs have ground,they are the standard European plugs. I did try it and i saw no difference whatsoever. I also tried to connect the amp's power supply to a completely different different plug in another room using an extension cord. still no difference, the buzzing persists
UPDATE.
i tried a differed laptop power supply, a 19volt one (previous was 24v) and the buzzing is still there but it has different frequency. I dont know if this helps.
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Could we please have a photo of the amplifier? Then, we can probably see if it uses an SMPS and if we shall try to solve the problem on the power side or the signal side.
Another quick test. Amplifier connected to the PC but no sound from the PC such that you can hear the buzz. When you pull the amplifier power plug from the socket (no turn off on the switch), does the buzz disappear at the same moment or when the amplifier dies out due to no supply voltage?
I did the quick test. The buzz disappears immediately when I disconnect the power. One this I noticed is that power blue led on the amp board attenuates its intensity, this attenuation is accommodated by a difference in the buzzing frequency. I don't know if I am explaining this well.
Here is the picture, I think you can see everything, as well as the blue light.(ignore the electric tape on the power plug it masks the an annoying led)
Attachments
A TPA3116 2.1 amplifier I guess. Used with an SMPS I assume?
Because the buzz disappears immediately when you pull the power plug, it seems that a harmful loop is formed from the PC power supply -> through the PC -> through the signal cable -> through the amplifier -> through the amplifier power supply -> through the net-wires to the PC power supply.
I have to cut the grass. In my next posting I will suggest you some (possible) solutions. Do you happen to have a DC power supply with an ordinary transformer and an output voltage of 12V-24V / 1A min.?
Because the buzz disappears immediately when you pull the power plug, it seems that a harmful loop is formed from the PC power supply -> through the PC -> through the signal cable -> through the amplifier -> through the amplifier power supply -> through the net-wires to the PC power supply.
I have to cut the grass. In my next posting I will suggest you some (possible) solutions. Do you happen to have a DC power supply with an ordinary transformer and an output voltage of 12V-24V / 1A min.?
How do I turn my common laptop psu with a European plug to ungrounded? Do I put electric tape on the ground contacts?
An smps? A switching power supply? I am not very sure, I guess it is?
At the end of your post you ask me if I have a DC psu with an ordinary transformer and 12-24v 1A min. I am pretty sure that what I use currently is this. It has an adjustable DC output 12-24v with 4A output at 24v.
This is its description:
Built in overload and short circuit protection, Automatic thermal, over current, over voltage cut off.
High output efficiency and stabilize, low ripple and interference.
Low standby energy consumption meeting with Energy Star.
Efficiency beyond 90%. (Condition AC115V full loading)
Power LED indicator.
Specifications:
Output power: 100W (Max)
Input Voltage Range: AC100-240V, 50/60Hz
Output Voltage: DC 12V/15V/16V16.5V//18V/18.5V/19V/19.5V/20V 5A DC 22V/24V 4A
And a photo(with the European plug not the UK one)
Attachments
Ahah of course i will teach you everythings about organic superconductors
(it is more in the hard chemistry side tho !) For the anti-pop, i have found that but i can't see where it is on my board ...
For the bootsrap snubber mod, sure it sounds contradictory but i checked again and it exists, you can find it page 469 of this thread, i don't understand how it works ^^
I removed the 100k resistor and it works like a charm with a reduced gain, i have no hiss when playing music, it is perfect !
By the way, when i put the volume pot to minimum and to maximum i have a lot more hiss, the hiss disappears when i am in the middle of the pot (at 12 oclock)
Instead of replacing electrolytic capacitors add c18 and c26, (10n or)100n I would pick but ask some other opinions. Check under heatsink other chip.
What is the role of these two capacitors ?
I can add them but i'm afraid i don't understand why
If it can improve somethings i will surely do this mod
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