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Old 31st March 2013, 05:59 AM   #191
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Location: iowa
I have a question.

I'm using the parts-express sure board with the tpa-3110.
2x8W @ 4 Ohm TPA3110 Class-D Audio Amplifier Board Only 320-329
I use 8 aa batteries to power it.

On some music I hear a static like noise (like fm static) like a kssch noise.
It happens on the leading edge of piano notes on the first 30 seconds of the last track on Diana Krall's "live in paris". It is a cover of Billy Joel's "Just the way you are."

Every time there is a percussive piano note, I get a kscht noise.

I run an active crossover to it. 4ohm 93db woofer, 8ohm 110db compression driver tweeter. Problem goes away when I disconnect the woofer (use other amp to drive woofer).

Do I need more capacitance in my supply ?
Am I clipping ?
Is it TIM distortion ?
What's going on ?

I'll disconnect the tweet later to make sure has something do do with the woof.

Otherwise the resolution is astounding, probably the 2x100uF caps help.

Oh, I also get full range audio sounding like digitized noise pumped through my subwoofer.

Norman
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Old 31st March 2013, 07:50 AM   #192
nesha is offline nesha  Serbia
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My tpa3110 started recently to add some noise over music, and I think chip is damaged .I was runing it directly (without a pot) with ESI Maya44 usb card (and Maya44 is not 'compatible' with sleep-mode of my PC, so I needed to replug it several times, sending a nasty 'thump' to the speakers) . Manuel of the Sure tpa3110 clearly states NOT to overload input of the amp with signals over 0.8V -it can damage the chip. So, I'm ordering a new one, it worked beautifully with my BetsyK mltl...
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Old 31st March 2013, 09:29 AM   #193
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Location: Dallas
That noise could also be flux residue from the solder paste.
I'm jut sayin' cause we used to build the EVM, and I know
that sound. Wash and bake it to be sure, wouldn't hurt...
I have nothing to do with the Sure board at PE, its just
an assumption that maybe they had the same difficulty?

It can be especially bad if some moron re-worker mixes
water soluble with no-clean, and traps some junk that
needs washing under gunk that can't easily be rinsed.
Or sometimes clean only what they can see on top, like
if we can't see the flux, it doesn't exist. Yeah, right...

On the other end of the same, sometimes the center pad
might not melt, and the paste would get washed out. Or it
would melt, but all be sucked down into the vias and not
wet the chip. Hard to say without using an x-ray to inspect.

Flip it over and melt plenty of extra solder through the
vias with a heat gun, and maybe you can salvage the
connection without removing the chip. Again assumption
the Sure board even has such vias in the pad? Might not...
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Old 31st March 2013, 11:48 AM   #194
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by norman bates View Post
I have a question.

I'm using the parts-express sure board with the tpa-3110.
2x8W @ 4 Ohm TPA3110 Class-D Audio Amplifier Board Only 320-329
I use 8 aa batteries to power it.

On some music I hear a static like noise (like fm static) like a kssch noise.
It happens on the leading edge of piano notes on the first 30 seconds of the last track on Diana Krall's "live in paris". It is a cover of Billy Joel's "Just the way you are."

Every time there is a percussive piano note, I get a kscht noise.

I run an active crossover to it. 4ohm 93db woofer, 8ohm 110db compression driver tweeter. Problem goes away when I disconnect the woofer (use other amp to drive woofer).

Do I need more capacitance in my supply ?
Am I clipping ?
Is it TIM distortion ?
What's going on ?

I'll disconnect the tweet later to make sure has something do do with the woof.

Otherwise the resolution is astounding, probably the 2x100uF caps help.

Oh, I also get full range audio sounding like digitized noise pumped through my subwoofer.

Norman
The fact that it goes away when not driving woofer is interesting. I think the woofer connected causes amp to have to drive more current which overshoots giving the sibilance. This my be one of the problems of running 6 ft of wire without a proper inductor and capacitor filter setup but only a ferrite bead. Try connecting the inductor and cap filter that the TI circuit recommends at the amp output before going to the speaker wire to see if it goes away. IIRCC, for 4 ohm speaker use a 15 uH inductor (on each wire to speaker) in series and a 2.2 uF (50 volt) to ground after the inductor. See if this will clean up the excessive hash produced by the PWM to drive the woofer, which then gets onto the tweeter.

Last edited by xrk971; 31st March 2013 at 11:52 AM.
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Old 31st March 2013, 02:45 PM   #195
DUG is offline DUG  Canada
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Location: mississauga ontario canada
Monitor your supply with an oscilloscope during high current passages.

Even a DMM may show supply drop.

http://data.energizer.com/PDFs/e91.pdf

Run the amp on a fixed power supply good for >5A and see if there is a difference.

IMHO AA size may be a small.

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Old 31st March 2013, 04:37 PM   #196
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Location: Montreal
Try connecting a Walkman, mp3 player, anything with a headphone volume control as recommended by the manufacturer. You could be overpowering the unit, it's only about 3 honest watts/ channel.
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Old 31st March 2013, 05:30 PM   #197
nesha is offline nesha  Serbia
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But Sure tpa3110 worked perfectly well, an sounded reeeealy good for the first 20 days,I was listening music using program-attenuation only (WMPlauer), so it's not bad solder I think. Stupid as I am, I did replugin' Maya's usb without cutting the power to amp, an after 10 or 15 such 'thumps' (plus some blackouts - diferent kind of noise thru the speakers) , litle businesscardsize amp started to put some 'krrrr...' over music. I 've bought Alps 50K log pot, but it was too late. So, Im waiting for a new one, at 9$ it's no brainer
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Old 31st March 2013, 07:31 PM   #198
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Location: Dallas
Water soluble flux: You can bake it dry, test it,
put it in a sealed bag, and pretend it works.
Till starts drawing water right back out the air.
Weeks or months later, depending humidity...

Even "dry", it seems to me viscous and oily.
Can't neutralize or get rid WS flux by baking.
It likes to hide under the edge, between the
pins and the ground pad. And the more dry,
the harder it is to get out with a short blast.
Takes time to re-absorb water, but a minute
is plenty long enough...

One of my pet peeves was a re-worker who didn't
understand every time you touch-up with a WS flux,
you have to thoroughly wash the board all over again.
Even if its been washed before.

Not just dab at the top of the rework with an alcohol
soaked q-tip and throw it in the oven. Like I won't
know the difference when it comes to test...

The q-tip is fine for cleaning enough to inspect the
progress of your work. But you really got to drown it,
else you are just smearing that flux around. It goes
into the vias and hides up under everything...

Again, I know exactly that sound you just described.
Nothing technical, just experience. If I didn't see or
measure anything else obviously wrong, send it back
to wash before I would request replacing anything.

----

I did have fun accident at the bed of nails testing house.
Needed to tombstone a part (lift up one end) to isolate
where a short was, there was nobody to do that for me.

Tried to use what looked like our WS flux, at their bench.
But it was actually a yellow inkjet refill bottle! I did not
spot the slight difference in color, and touched the drop
with an iron. What a mess one tiny ink drop can make!
Splattered everywhere...

Last edited by kenpeter; 31st March 2013 at 07:57 PM.
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Old 31st March 2013, 08:08 PM   #199
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Location: iowa
k.
thanks.

I'm betting on the current, supply problem.

Norman
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Old 1st April 2013, 08:50 AM   #200
nesha is offline nesha  Serbia
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Location: Beograd, Serbia
Quote:
Originally Posted by kenpeter View Post
Water soluble flux: You can bake it dry, test it,
put it in a sealed bag, and pretend it works.
Till starts drawing water right back out the air.
Weeks or months later, depending humidity...

Even "dry", it seems to me viscous and oily.
Can't neutralize or get rid WS flux by baking.
It likes to hide under the edge, between the
pins and the ground pad. And the more dry,
the harder it is to get out with a short blast.
Takes time to re-absorb water, but a minute
is plenty long enough...

One of my pet peeves was a re-worker who didn't
understand every time you touch-up with a WS flux,
you have to thoroughly wash the board all over again.
Even if its been washed before.

Not just dab at the top of the rework with an alcohol
soaked q-tip and throw it in the oven. Like I won't
know the difference when it comes to test...

The q-tip is fine for cleaning enough to inspect the
progress of your work. But you really got to drown it,
else you are just smearing that flux around. It goes
into the vias and hides up under everything...

Again, I know exactly that sound you just described.
Nothing technical, just experience. If I didn't see or
measure anything else obviously wrong, send it back
to wash before I would request replacing anything.

----

I did have fun accident at the bed of nails testing house.
Needed to tombstone a part (lift up one end) to isolate
where a short was, there was nobody to do that for me.

Tried to use what looked like our WS flux, at their bench.
But it was actually a yellow inkjet refill bottle! I did not
spot the slight difference in color, and touched the drop
with an iron. What a mess one tiny ink drop can make!
Splattered everywhere...
So, I can try baking and if problem temporarely goes away, its a bad flux problem? What temperature and time of baking do you recomand?
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