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TPA6120A2 best headphone amp in the world? - Page 6

post #76 of 110
Maybe you can buy the evaluation module from ti online. For only $49, you get their board and a lot of good parts already put together. Just have to add a power supply.
post #77 of 110
Thats an interesting idea! Do you have the link to the evaluation module? I tried searching TI but couldnt find it.

Is it anywhere on the TPA6120A page?

http://focus.ti.com/docs/prod/folder...tpa6120a2.html

EDit: oh wait, i think i found it, am checking up on it now
post #78 of 110
Hmm...i definitely like the look of it....might definitely give it a try(although nothing beats making it yourself eh?). I'm quite new to chipamps, is it normal for TI to offer evaluation boards for their chips like this one? I'm pretty surprised no one has tried it yet! Also, the schematic for their evaluation board looks very much more complicated compared to the application diagram found on the chip's data sheet(that schematic was the one i was initially planning on following). I suppose its a stupid question to ask, but which one is better?


BTW i have attached the schematic for the evaluation board here.

ROFL...the pics too small now that it fits in the attachment limit,

the link to the evaluation board pdf and schematic is here:
http://focus.ti.com/general/docs/lit...9&fileType=pdf
post #79 of 110
The schematic is basically the same since R13, R14, R15, and R16 are not installed. R11 and R12 are just jumper wires. They did add the 4.02K ohm resistors R9 and R10 to keep the DC output offset down. They also added capacitors to make sure the power was good. These changes do make it better.
post #80 of 110
how about their part selection... is there room for improvement in selecting the quality of parts?

they got panasonic caps from digikey
tdk ferrite beads from digikey
vishay and thin film technology resistors from vishay and thin film technology
rca jacks from switchcraft
usm eyelets banana jacks from bisco
aluminum shandoffs from digikey
switchcraft kheadphone jack from digikey

are there components there that you would replace?


i didn't list it all the part numbers but they are found in table 4.1 of the EVM pdf file

and as far as the pot.... panasonic evj or alps blue? which is better?


what other changes would you make?
post #81 of 110
is there a pot in the evaluation board? i didnt notice it...which part is it from the table?

dip16amp> Thanks a lot. The more i think about it, the more i like the idea of giving the board a try. Some of the components in there look pretty good. I'm not very familar with electronic components and branding but i've heard some good things about the panasonic caps and the vishay resistors at least.

maybe i could just mount the evaluation board in a case and extend the inputs/ outputs to the case and that would be it. Oh yes, not forgetting the power supply too
post #82 of 110
If you need a volume control, then you would need to add a pot. Alps blue would be better than a Panasonic EVJ but either would work fine. A stepped attenuator would be best.

For portable use, two 9 volt batteries would work but a +15V and -15V power supply would sound better for home use.
post #83 of 110
just to confirm before i place my order.

which would be better to drive grados... this tpa6120a evm or an A47?
post #84 of 110
The TPA6120 has much more power than the A47 and works best with a dual voltage power supply. It may not run as long on batteries as the A47 though.
post #85 of 110
will that much more power make much of a difference for hp-1000s?

what would you suggest for a DIY portable dual power suppply if i choose the tpa6120a
post #86 of 110
The bass will probably sound pretty weak with the TPA and Grados. My reasoning being the required 10 ohms output resistance for stability. Given the Grados are only 32 ohms to begin with, this will mess up the damping factor pretty bad. I believe Kevin Gilmore also said he tried it, and the bass was in fact pretty weak.

On a second thought, please take a look at the attached schematic. Got a technical question. Pretty sure, but want to be certain. If this TPA configuration is driven with a true balanced input, the ground connection shown shouldn't be necessary. It should float at ground. Am I correct? The voltage at the inverting inputs on either side should be equal in magnitude but opposite in polarity with respect to ground. So given the two 1k resistors are matched extremely well, that point should be virtual ground. Does this reasoning stand up?
post #87 of 110
I find the bass to be stronger than the BUF634 buffer. Could try a couple of 12V battery packs. If you want a good portable amp for Grados, then I would go with the RA-1 circuit.

I think the ground is needed on the 1K ohm resistor to set the gain and to keep the DC output offset from going to the rails. Figure 26 on the data sheet would be a true differential circuit for the TPA6120.
post #88 of 110
i really would ideally like to build a PPA, but

1) i can't afford to build it now. if i am going to build it i am going to go all out and that is going to be like $250USD

2) I have some experience building circuits, but never audio circuits so I am going to start with something simpler.


so it's between an RA-1 and an A-47 i guess

i was looking at Sijosae's amps on headwize and they are beautiful....

how do other DIY amps like the porta corda, basic szekeres and mini SDS do with grados?
post #89 of 110
Quote:
Originally Posted by intlplby
basic szekeres and mini SDS do with grados?
The szekeres is very good. You could also have a look at the Zen headamp.
post #90 of 110
Quote:
Originally Posted by dip16amp
I think the ground is needed on the 1K ohm resistor to set the gain and to keep the DC output offset from going to the rails. Figure 26 on the data sheet would be a true differential circuit for the TPA6120.
But I'm not going balanced to single ended. I'm staying balanced. So I'm using the TPA as dual buffers. Exactly like figure 24.
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