[thoppa]

Hi,

I'm waiting to get a used TPA6120 EVM so I can see if it can deliver the goods, and if so, what it needs to do it. Then maybe I'll be able to get the ST(X) to deliver too.

The EVM can take +/-15V and the IC can output 80% of that rail to rail. So that is a 24V swing - enough for high impedance cans ? What cans have you used with your +/-15V setup ? Is it a single IC or multiple balanced design ?

 

[chinesekiwi]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif maybe the $2.25 price tag(prolly cheaper in bulk) is a mere indication of a plausible answer?

Most DACs are around $10 tbh.
As you know in audio, price is only a very rough indication of quality.
That said, in the greater realms of things, it is of a low-end amp.
Can you get a better 'DAC' + headphone amp combo for the price?
No.

 

[ROBSCIX]

Quote:

Originally Posted by thoppa /img/forum/go_quote.gif Hi, I'm waiting to get a used TPA6120 EVM so I can see if it can deliver the goods, and if so, what it needs to do it. Then maybe I'll be able to get the ST(X) to deliver too. The EVM can take +/-15V and the IC can output 80% of that rail to rail. So that is a 24V swing - enough for high impedance cans ? What cans have you used with your +/-15V setup ? Is it a single IC or multiple balanced design ?

Did you check the spec sheet for tips and ideas for reference circuits?
May give you some ideas as to what you would need to do to get what you want.

 

[Seaside]

TPA6120 itself is very powerful chip, powerul enough to blow low impediance headphones at its full swing. It surely can drive 600ohm cans with ease when the supply V is high enough.

But as always, the chip itself is just a part of equation. To get that level of power, other circuits arround it should be properly implemented, and adequately high V should be applied. The chip is kind of tricky to work with, IMO. Certain resistors and capacitors should be placed very close to the chip, otherwise the sound out of it could be harsh and unimpressive. Assuming that Asus did good job, it should be powerful enough to handle most headphones.

 

[leeperry]

Quote:

Originally Posted by chinesekiwi /img/forum/go_quote.gif Most DACs are around $10 tbh. As you know in audio, price is only a very rough indication of quality.

luckily, the line-out has a pretty high gain on the STX, and using an op-amp able to take high loads is a much better option IMHO...I find a $5 OPA2132P far more capable/enjoyable than this $2.25 "thing"

 

[thoppa]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif Did you check the spec sheet for tips and ideas for reference circuits? May give you some ideas as to what you would need to do to get what you want.

Yeah, the pdf for the evm is ace. I think the first thing to try is to match power - use the same kind of quality linear power for the EVM as I use for the Asus ST so it is a 'level playing field'. Then I'll try playing with the output impedance of the EVM circuit, try different components and values, etc.

 

[thoppa]

Hi,

I got the evb, made a +/-15V psu, added a simple volume/pre-amp/bass boost stage too using an LME49720MA, and did some modifications to the tap6120a2 evb (changed some of the caps and the feedback resistor so there is more gain). The DC offset is 10mV with no input signal without putting any caps in the signal path, and it sounds fluid, detailed, and with lots of punch and definition. There's no question that the tpa6120 is a very good headphone amp, and has the balls to make my HD650 jiggle my little grey cells. But it doesn't do nearly as well in the Asus Essence and there's quite a difference. The Essence's tpa6120 can have an aggressive edge to it and just doesn't sound as fluid.

So, my conclusion is that if I want the Essence to reach it's full potential through the tpa6120 output, I'm going to have to find out why it falls short of its potential and do some mods.

I'm thinking it could be the +/-12V on board power regulation circuit ( I have an independent linear psu for the Essence already so it isn't the source power ), it could be the remaining caps that I haven't upgraded to Elna Silmic, it could be something to do with the I/V gain stage (the smt feedback caps look suspect).

Anyone have any other ideas ?