Author Topic: Opinions on ebay DIY kits  (Read 1373 times)

0 Members and 1 Guest are viewing this topic.

Offline NoradIV

  • Contributor
  • Posts: 23
  • Country: ca
Opinions on ebay DIY kits
« on: April 03, 2017, 01:29:25 pm »
Hello Everyone,

I have an old Audio Reflex AR-620 head that is dying. (One problem is probably dirty contacts, the rest is likely related to bad caps).

I mostly use this head unit as a headphone amplifier for my AKG k271 MK II.

These headphones have somewhat a high impedance and low sensitivity, meaning that the built-in sound card in my computer isn't exactly up to the task.

I also like my music pretty loud and bassy, so a decent output is necessary.

I am not a crazy audiophile (most of my music is in MP3), I do not care about the lamp thing, I just want something that will be an improvement to my built-in sound card and preferably DIY (I like assembling kits).

I found this kit on ebay. I verified the specs of the TPA6120, which has a 1.5W output and otherwise decent specs.

I'd like to know what you guys think.

Thanks!
 

Offline CatalinaWOW

  • Super Contributor
  • ***
  • Posts: 2455
  • Country: us
Re: Opinions on ebay DIY kits
« Reply #1 on: April 03, 2017, 02:06:26 pm »
For fifteen bucks it is worth a try.  Not much lost if it doesn't turn out as good as you want.  But if you do like it you will have to spend some money on a nice case power supply to turn it into a daily user.  That piece of the equation might convince me to go for something already packaged up nicely.
 

Offline NoradIV

  • Contributor
  • Posts: 23
  • Country: ca
Re: Opinions on ebay DIY kits
« Reply #2 on: April 04, 2017, 10:17:24 am »
For fifteen bucks it is worth a try.  Not much lost if it doesn't turn out as good as you want.  But if you do like it you will have to spend some money on a nice case power supply to turn it into a daily user.  That piece of the equation might convince me to go for something already packaged up nicely.

If I like it, a steel case and a proper power supply will be part of it. I like the idea of being able to change the amplifier later if I want, keeping it more "modular".

Oh, and I'd rather assemble it myself than order one all made, DIY is a plus for me, since I like assembling them.
 

Online blueskull

  • Supporter
  • ****
  • Posts: 9596
  • Country: cn
  • Power Electronics Guy
Re: Opinions on ebay DIY kits
« Reply #3 on: April 04, 2017, 10:33:11 am »
All integrated HP amps have load issues. The higher the output amplitude (V or I), the higher the distortion, and you simply cannot get rid of this without using larger die area.
To me, a LME49610+LME-whatever-opamp solution is better than all in one TPA6120, and a carefully designed full discrete output stage coupled with a high end opamp is even better.
Therefore, I'm not a TPA6120 person, but for the price, you cannot really get a properly designed and built discrete amp, so go for it.
SIGSEGV is inevitable if you try to talk more than you know. If I say gibberish, keep in mind that my license plate is SIGSEGV.
 
The following users thanked this post: cdev

Offline NoradIV

  • Contributor
  • Posts: 23
  • Country: ca
Re: Opinions on ebay DIY kits
« Reply #4 on: April 04, 2017, 11:46:24 am »
Ok, then let me check for another option. I have no knowledge of these designs really. I figured TI was trustworthy, if they publish a HIFI chip, I would have thought it would do what they said it would do.

Although, these are headphones, not speakers.
 

Online blueskull

  • Supporter
  • ****
  • Posts: 9596
  • Country: cn
  • Power Electronics Guy
Re: Opinions on ebay DIY kits
« Reply #5 on: April 04, 2017, 12:09:04 pm »
I figured TI was trustworthy, if they publish a HIFI chip, I would have thought it would do what they said it would do.

There are some traps in TI datasheets, for instance, their OPAMPS (OPA1602/12) are rated ultra low THD/IMD, only under very low input impedance and very high output impedance, and their "THD" is measured not directly with an audio analyzer because it is too low. They invented a new method to equivalently measure it, but how accurate it is, I have no idea. The old LME series are rated closer to real world condition.

Also, TI's reference DAC designs don't use TI's latest best opamp devices, they use older devices instead. There must be a reason, and cost is not one -- their PCM1792A/1794A are commonly found in $1000+ audio gears.

Nevertheless, TI makes some of the world's best analog audio chips. Just don't expect directly lifting reference schematics from datasheet will give you good sound. Even for a simple low power HP amp there are quite some engineering effort needed to extract the max performance of the silicon.

When it comes to headphone audio, the seemingly easy (20kHz max, 100mA max, 10V max) task is much harder to get done properly.
SIGSEGV is inevitable if you try to talk more than you know. If I say gibberish, keep in mind that my license plate is SIGSEGV.
 
The following users thanked this post: cdev, moz


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf