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Old 7th March 2005, 10:47 AM   #11
Electrons are yellow and more is better!
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What values of the feedback of the TPA6120 have you chosen? Have you used SMD parts?

Why don't you filter out the 5.6 MHz to a lower value?
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Old 7th March 2005, 10:58 AM   #12
stry is offline stry  Greece
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Topology is non-inverting.

I used 2k (feedback) and 1k for neg. input to GND.

No SMD parts. The feedback resistor is of highest quality (see my first post).

PCB bank is very close to pins and is red ELNA starget 100 uF in parallel with WIMA 100nF MKS (a pair per leg and per channel).

The analog filter has -3dB @ 48 kHz.

By setting a different cutoff (e.g. 24 kHz) the level alters only -6dB lower, thus no real gain is obtained.
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Old 8th March 2005, 09:23 AM   #13
stry is offline stry  Greece
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You can see photo of the internal of my amp at:

http://www.avforum.gr/showarticles.p...subtopic=23782


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Old 8th March 2005, 09:25 AM   #14
stry is offline stry  Greece
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Later, i will post photo of the external PSU (15 times bigger !!)
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Old 8th March 2005, 09:37 AM   #15
Electrons are yellow and more is better!
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When I see the pictures I think I see the problem. Texas recommends SMD parts, groundplane and a real tight design. As you may know the feedback resistor is extremely sensitive when it comes to current feedback and this kind of speed, 1300 V/us! I'll suspect you never can get this work properly with your building style.

I'll supect that the design must look like this or similar. I think you shouldn't underestimate the importance of a good pcb especially when you are using this ultrafast IC. Your input wires are good antennas.
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Old 6th May 2005, 04:31 AM   #16
ljordan is offline ljordan  United States
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Default Minimaist approch, in a player...

I put this in my Sony dvp-ns900v.
Direct to the akm4383.
I pulled out all the chips on the analog board to free up power.
I used an old Tamradio 2400 ohm to 600 ohm xformer.

The sound is so good.
But the offset V comes close to 100mv as I get the linear pot about half way, loud! Over 200mv full turn.

The gain is r2/r1 + 1.
So 10.

The second image I got off the net.
It shows a gain of 100.

I am tring to get an offset I can live with and still not use an input chip or buffer.

I want to next try another Tamradio that is 1 to 1 ( 600 ohms in and out) also CT in, SE out. Thereby reducing the gain needed.

It seems the offset is related to the gain.




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Old 6th May 2005, 04:32 AM   #17
ljordan is offline ljordan  United States
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Default Minimaist approch, in a player...

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Old 6th May 2005, 10:27 PM   #18
weissi is offline weissi  Europe
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Sorry for beeing a little bit o.T. forgive me :-)

I´ve built an amp with the THS6012 a while ago, it sounded nothing than superb... Last time surfing on the Analog hompage I read about the AD8397, a high current opamp with quite good but not that impressive spec´s as the Ti THS-type.
Anyway, I put it in the output/filter stage of my EMU0404 - as a line driver it can´t be bad I thought.
But: When I drive my K271s (and those AKG´s are known for their high demands on amplification to reproduce good low freq.)directly from the card, bypassing the THS, I can hear absolutely no difference - even with brain-damaging levels...

Another thing: I made also good experience with an THS4222 in my Prodigy7.1 (MSOP) also a impressive improvement over standard opamps...
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Old 7th May 2005, 03:49 AM   #19
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quick question about this chip.

Is it safe to connect all the 10 NC pins to ground (and the powerpad)
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Old 7th May 2005, 04:57 PM   #20
ljordan is offline ljordan  United States
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Default neutron7:

I ground down the unused top and bottom end with a dremel tool. This was to get access to the ground connections that go to the power pad. These are visable on each end of the chip but they are reccesed.

I needed to do this because I epoxied the chip to a heat sink. I exposed the ground leads and made them the centre-point on me star ground.

I doing so I saw that the NC leads all run to the die but are not connected at that point. SO If you did ground the nc leads I think you would cause more net capacitance around the die and the touchie neg input lead.

What are you tring to do with the tpa?


BTW I assume this is a relabled ths6012 and it's appl data would apply. Can anyone can any one confirm this so I don't turn into something worse than a pumpkin.

Can anyone say (help) as to the best, lowest values for r1, r2 to get the offset lower. Im using 1k and 10k now. maybe 100 and 1k (gain of 11).
ALSO could I use a lower value pot? I am going to a 1 to 1 trans. so I could lower the gain to maybe 5.
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