whining/whistling/squaling on dug-1 build
Shamelessly cross-posted over from the DUG group buy thread, as it seems (almost) no one is paying attention to it.
I just finished assembling my second DUG-1 dual mono-amp. This weekend I did the first test, and everything works, but there is a "whistling" or "squelching" sound. The squelching is fairly quiet, as it can be mostly drowned out with modest-level music. It sounds like a tea kettle coming to boil (though not nearly as loud) or like the wind howling at night. It's coming out of both channels. It doesn't seem to scale with volume. In this particular test, I was using my smartphone to send the signal to the amp (1/8 stereo to dual RCA).
For this build, I'm using an Edcor TTPC15K/15K for DC-blocking and unbalanced to balanced conversion. Instead of capacitors for C2/C3, I used 0-ohm resistors (jumpers). I attached the schematic of the transformer below.
Here's the (naive) wiring I did:
RCA POS to T1 Pin 1
RCA GND to T1 Pin 3
T1 Pin 7 to Amp Input POS (i.e. series with C2)
T1 Pin 6 to Amp Input GND
T1 Pin 5 to Amp Input NEG (i.e. series with C3)
I thought maybe the squelching/squealing/whistling sound might have been due to the RCA-to-transformer side of things (since it was taped in place as a temporary testing measure). But I completely removed everything from the input side of the transformer, and the sound remained.
Based on the little web research I did, I suspect the transformers are microphonic and picking up some noise somewhere... earlier in this thread, I recall at least one person using transformers (not Edcors, but same idea I think) created some kind of RC snubber circuit. Perhaps such a thing is needed here?
Also, FWIW, I'm using an Astron SL-11R (linear regulated 13.8V) power supply. As per cjkpkg's suggestion in the other thread, I will try another PSU when I get a chance. I know the wiring is messy, I intend to the clean that up. I believe the amps should be reasonably decoupled from the PSU, with those 4x5600uF caps. (This thing will play for a good eight seconds even after the PSU is shut off.)
Happy to hear any thoughts or ideas, thanks!
Shamelessly cross-posted over from the DUG group buy thread, as it seems (almost) no one is paying attention to it.
I just finished assembling my second DUG-1 dual mono-amp. This weekend I did the first test, and everything works, but there is a "whistling" or "squelching" sound. The squelching is fairly quiet, as it can be mostly drowned out with modest-level music. It sounds like a tea kettle coming to boil (though not nearly as loud) or like the wind howling at night. It's coming out of both channels. It doesn't seem to scale with volume. In this particular test, I was using my smartphone to send the signal to the amp (1/8 stereo to dual RCA).
For this build, I'm using an Edcor TTPC15K/15K for DC-blocking and unbalanced to balanced conversion. Instead of capacitors for C2/C3, I used 0-ohm resistors (jumpers). I attached the schematic of the transformer below.
Here's the (naive) wiring I did:
RCA POS to T1 Pin 1
RCA GND to T1 Pin 3
T1 Pin 7 to Amp Input POS (i.e. series with C2)
T1 Pin 6 to Amp Input GND
T1 Pin 5 to Amp Input NEG (i.e. series with C3)
I thought maybe the squelching/squealing/whistling sound might have been due to the RCA-to-transformer side of things (since it was taped in place as a temporary testing measure). But I completely removed everything from the input side of the transformer, and the sound remained.
Based on the little web research I did, I suspect the transformers are microphonic and picking up some noise somewhere... earlier in this thread, I recall at least one person using transformers (not Edcors, but same idea I think) created some kind of RC snubber circuit. Perhaps such a thing is needed here?
Also, FWIW, I'm using an Astron SL-11R (linear regulated 13.8V) power supply. As per cjkpkg's suggestion in the other thread, I will try another PSU when I get a chance. I know the wiring is messy, I intend to the clean that up. I believe the amps should be reasonably decoupled from the PSU, with those 4x5600uF caps. (This thing will play for a good eight seconds even after the PSU is shut off.)
Happy to hear any thoughts or ideas, thanks!
Attachments
Last edited:
The transformers themselves, or the wiring to/from them?
I have used these transformers before, though briefly, in another build (there's pics somewhere in this thread). And I also loaned these to rhing and he used them for a while, never reported any issues (also pics/writeup buried in this thread).
But, when I previously used them, it was balanced-to-balanced. And I think when rhing used them, it was unbalanced-to-unbalanced. So I believe this is their first use of unbalanced-to-balanced...
Not yet, i.e. only tested with chassis open (as in the pics above).
But that brings up another related question: what is the proper way to ground the chassis, given that the PSU is in a separate box? In my other builds I've had the PSU and amp in the same enclosure. I use a three conductor mains cable, and short the mains earth to the chassis. But I have no convenient earth available in this build...
Either!
Hey Clengman,
In my estimation you couldn't go wrong with either of those boards. I own both. The "blue/black" board is the subject of much discussion and modifications. Both my boards are just stock.
Pick one, or both. They're cheap enough!
Mark (from the other end of the state)
Hey Clengman,
In my estimation you couldn't go wrong with either of those boards. I own both. The "blue/black" board is the subject of much discussion and modifications. Both my boards are just stock.
Pick one, or both. They're cheap enough!
Mark (from the other end of the state)
I've observed (and read many comments about) that whenever a (relatively) high impedance is seen by the input of these chip there seems to be "noise" pickup.
In your case the transformers themselves may be the culprit.
Are the cores of the transformers grounded to the board ground?
Do the secondaries have a CT that could be AC coupled to board ground?
There may be hope.
I have used direct drive out of an mp3 player and noise does not seem to be an issue.
My TV amp (PBTL boards) is driven from LME49710's on both the inverting and non-inverting input lines from another box...dead quiet.
Hello,
I'm trying to choose components for a simple stereo amp/compo for my son's bedroom. I've decided to try a 3116 chip (already have an Amp6).
I would prefer simplicity and ergonomics over pure sound quality. So, in order to avoid a spahetti of cables, PS's and many differnt boxes, I'll try to fit a 3116 amp and it's PS inside a Sony CD player. There is plenty of room inside it. If not, then I have a spare pioneer cdr case...
A few questions about the amp.
Will the 3116 amp be ok with 8ohm speakers? Or should I go to the 3118 chip?
Will this PS board suffice for the 3116 amp?
AC 85-265V to DC 12V 8A AC/DC 50/60Hz Switching Power Supply Module Board RS | eBay
I also have a PC PS which is available for modding.
Is this a decent board, for a low demand project like this?
50Wx2 Official Version Finished TPA3116D2 Stereo Digital Power Amplifier Board | eBay
Thank you,
Dimitris
I'm trying to choose components for a simple stereo amp/compo for my son's bedroom. I've decided to try a 3116 chip (already have an Amp6).
I would prefer simplicity and ergonomics over pure sound quality. So, in order to avoid a spahetti of cables, PS's and many differnt boxes, I'll try to fit a 3116 amp and it's PS inside a Sony CD player. There is plenty of room inside it. If not, then I have a spare pioneer cdr case...
A few questions about the amp.
Will the 3116 amp be ok with 8ohm speakers? Or should I go to the 3118 chip?
Will this PS board suffice for the 3116 amp?
AC 85-265V to DC 12V 8A AC/DC 50/60Hz Switching Power Supply Module Board RS | eBay
I also have a PC PS which is available for modding.
Is this a decent board, for a low demand project like this?
50Wx2 Official Version Finished TPA3116D2 Stereo Digital Power Amplifier Board | eBay
Thank you,
Dimitris
A TPA3116 is fine for 8ohm speakers. The amp capacity of the 12V supply you reference is more than adequate. However, at 12V, you will get about 6-7 watts of distortion free power per channel. With a TPA3116 based amp, you can use a 24v supply to get about 27watts into 8 ohm speakers. And for simplicity's sake, you could order a TPA3116 based amp with a built in volume control like this one (there are many other choices as well):
TPA3116 2*100W D2 Dual Channel Digital Audio Amplifier Board 12V-24V for Arduino | eBay
Thanks for the suggestion. I was planning to try one of these for a mono speaker. Maybe I'll try two in stereo sometime.
Thanks. I've seen posts about "YJ red" boards and "YJ blue" boards, but when links are provided, they are usually links to expired ali or ebay listings. It's been tough to figure out what, exactly, is what. This helps.
The only successful path for getting the best sound and no pops from this board is by getting the 'Green board'.
I had 2 of it after the caps and snubber mod and pbtl mode and works extremely well. Surprisingly as par with my MyRef C gainclones.
Just pay attention with the power source. The LT1085 works well. And make sure the Left and Right input is not inverted. My board is. Left input goes to Right and Right input goes to Left input of the TPA chip.
I had 2 of it after the caps and snubber mod and pbtl mode and works extremely well. Surprisingly as par with my MyRef C gainclones.
Just pay attention with the power source. The LT1085 works well. And make sure the Left and Right input is not inverted. My board is. Left input goes to Right and Right input goes to Left input of the TPA chip.
Last edited:
That's a lot of good information all in one place! Thanks!The only successful path for getting the best sound and no pops from this board is by getting the 'Green board'.
I had 2 of it after the caps and snubber mod and pbtl mode and works extremely well. Surprisingly as par with my MyRef C gainclones.
Just pay attention with the power source. The LT1085 works well. And make sure the Left and Right input is not inverted. My board is. Left input goes to Right and Right input goes to Left input of the TPA chip.
This board does not look at all familiar to me though. Is it for sale anywhere currently?
Also, regarding the "popping." I've read that this is a common problem and I've read about a lot fixes, but popping is one thing I've never heard from the amp I have now. Turning on and off using the switched volume pot is silent.
Last edited:
I'm definitely interested to know what you found inadequate about these two boards. Thanks!
I bought on of these:
The new version 2.1 high power 50W+50W+100W digital finished amplifier DAC TPA3116D2 surpass LM1875-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
It sounds awful in the highs!
Never heard worse vocals in the ssss!
Is it something wrong with this amp?
Or something to modify?
I run PC-ES9023 DAC-TPA3116D2 18,5v 4,5A Laptop power-Fullrange Tangband W4-1320.
I can hear some potential good amp here but the highs killing me!
Also some depth is missing.
My Tripath TA2020 sounds much better!
The new version 2.1 high power 50W+50W+100W digital finished amplifier DAC TPA3116D2 surpass LM1875-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
It sounds awful in the highs!
Never heard worse vocals in the ssss!
Is it something wrong with this amp?
Or something to modify?
I run PC-ES9023 DAC-TPA3116D2 18,5v 4,5A Laptop power-Fullrange Tangband W4-1320.
I can hear some potential good amp here but the highs killing me!
Also some depth is missing.
My Tripath TA2020 sounds much better!
I have this amp. The layout is similar between two versions except for the PS capacitors.
Hers a rough schematic ... It's easier to read if you download it to your PC and open with Windows photo Viewer or similar app.
The L-R channels actually measure pretty flat with a slight decrease starting at 3Khz on up to 10Hhz where its -3db.
The sub channel on the other hand starts with a 1st order inverting band pass prior to summing the L-R channels (upper left in schematic). The band-pass low end's Fc is 34 Hz. This reduces the very low end base on the sub channel. You can get a lot back by substituting 10uf electrolytic capacitors for the existing 1uf decoupling caps (C1 & C2 in the schematic). I'm currently using it as-is to manage x-max on my sub.
After summing, the combined L-R signal is modified by a Sallen-Key 2nd order LP filter set at 107hz. You can modify the LP by changing the polyester caps C21 & C22 (mine is modified to 876hz). I have a legend for the physical board if your interesting in substituting capacitors.
On the bright side, there's no-turn or turn-off pop whether you use the switch or (un)plug in the power supply. Some mentioned that the switch only encages mute. I'll have to test current draw on idle to see if the switch actually turns-off the TPA3116 chips..
Last edited: