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TPA6120A2 best headphone amp in the world? - Page 7

post #91 of 110
i can't seem to find a thread about the MINT with grados (or the pimeta)


it seems that whenever i use the search function it always finds a bunch of irrelevant threads because the keywords happen to be part of people's signatures
post #92 of 110

TPA6120A2 build

I managed to build a test model with a regulated +/- 12v power supply and have the chip on a small piece of pcb with the pad soldered to a wide copper track which in turn is clamped to a small heatsink. It is working but had some noise at turn on - then the chip gets fairly hot. Anyone managed to make a simple pcb for this chip - and could lengths of leads to the legs cause the noise?
Sorry - no pics at the moment.
post #93 of 110
Thread Starter 

I have ordered samples and will definitely make a pcb. This will be an autum project.


Edited by peranders - 8/23/10 at 1:11pm
post #94 of 110
Quote:
Originally Posted by chrisallan
I managed to build a test model with a regulated +/- 12v power supply and have the chip on a small piece of pcb with the pad soldered to a wide copper track which in turn is clamped to a small heatsink. It is working but had some noise at turn on - then the chip gets fairly hot. Anyone managed to make a simple pcb for this chip - and could lengths of leads to the legs cause the noise?
Sorry - no pics at the moment.
Should be ok if the .1 uF caps are within a quarter inch of the chip. Otherwize, it may be oscillating and causing it to get hot. It should only get warm under normal use.
Did you include the 4.02K resistors that are shown in the evaluation board manual. That will keep the DC offset down when there is no source connected. It will go to the rail and draw mad current without it.
post #95 of 110
I've had another shot at this project. Better heatsinking, better wiring and added .1 uF caps 4.02K resistors as per the EVM. I've managed to get noise almost down to nothing but am getting a channel imbalance problem. It's suspiciously like the problem a gainclone had when one of the input signals was inverted : although the stereo image sounds fairly even, vocals are pulled to one side. Also if I pull one of the inputs, the result is a mono, centered signal. This only happens one one channel. I've checked the wiring several times to no avail. Anyone had this. I suspect the vocals show the effect most as it effects the signals most that are identical in each channel.
Weird!
post #96 of 110
Seems like maybe a ground problem. Make sure all the grounds are connected together. Shound be grounds for power, input signal, output signal, and the negative input resistor for unbalanced use. Should also have the 10 ohm resistors in series with the outputs and 50 ohm resistors in series with the inputs.
post #97 of 110

Thanks dip16amp

It was a very basic problem - incorrect wiring of the heaphone socket - doh!
Now its really a runner, incredibly clean and fast sound - no muddling of complex pieces, plenty of volume and plenty of space around the sound.
I'd like a bit more bass, but apart from that, Im very pleased with it.
post #98 of 110
A suitable opamp could be used with the TPA as a buffer inside it's feedback loop. That would address the 10 ohms output impedance / damping factor problem with low impedance headphones.
post #99 of 110
Quote:
Originally Posted by intlplby
i can't seem to find a thread about the MINT with grados (or the pimeta) it seems that whenever i use the search function it always finds a bunch of irrelevant threads because the keywords happen to be part of people's signatures
The mint sounds very nice with my SR225s and my D-EJ2000
post #100 of 110
Just built this amp a few days ago, sounds very good. It's the only amp next to the Gilmore Dynamic and A47 i have not been disappointed by after hype.
I still have quite high dc offset even with 4.32k resistors from the input to ground, around 20-30mV.
post #101 of 110
Well did a bit of tweaking and got dc offset in half by adding .01uf caps.
post #102 of 110
I sent some email to TI asking about the possibility of getting a spice model. Here is what they said:

Quote:
Thank you for your inquiry regarding the TPA6120A2. Unfortunately, the product group has chosen not to offer any simulation models on these devices. Please let us know if there are specific questions you would like answered which will assist in your application and/or design. We apologize for any inconvenience this may cause and if there is anything else that we can help you with, please let us know.
Bumber. Not sure why they chose not to make a model. I guess they figure the expense of making the model is not worth any additional interest in the product and thus additional revenue.
post #103 of 110

News?

Hi,

Anyone have any new experience with this chip lately?

 


Edited by Question - 11/14/11 at 5:18pm
post #104 of 110
Thread Starter 

This is my most successful amp design so far despite the fact that it's made of SMD parts.


Edited by peranders - 6/26/14 at 1:34pm
post #105 of 110
Dear All:

To achieve a gain of 5 Can I use a Rf=5000 ohm and Ri=1000 ohm or Do I have to use Rf=1000 Ohm and Ri=250 Ohm ?

I will use the R9 resistor = 1.6K to reduce the DC offset voltage.

Schematic: (Evaluation Board)
http://www.ti.com/lit/ug/slou169/slou169.pdf


Regards.
Alfredo Mendiola Loyola
Lima, Peru
Edited by mendiola - 6/6/14 at 1:05pm
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