Headphone amp idea....

Hi, first time poster.

I've been planning on building a headphone amp (for home use) for a friend and initially started looking into a tpa6120 based chip amp, then I moved on to an OPA134 based design since I wanted to use DIP8 sockets (or something else that would be easier to assemble.

While looking at some existing OPA134 designs out there, I stumbed accross people using a IC voltage divider (the TLE2426) and then a buffer after the divider (BUF634).

Well, the cogs started turning and I'm wondering about doing an amp with a voltage gain stage and then a buffer using TIs OPA627/637 followed by the BUF634 (not set on these in particular, but they seemed like they would work)

My first impression is that this would be very accurate and have a high current, low impedance output too, but I'm sure I'm missing something :smash:

Anyone have any thoughts on this idea?

Thanks!

Rob
 
This solution works well. I used a similar design some time ago on a Audio and Video Mixing desk I was working on. It was based on an aplication note from from TI. I can't find that one at the moment but found this which is very similar. Here 3 buffers are used but for driving a headphone amp you could get away with one (I did and it worked very well).

Regards,
Andrew
 

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Mike Gergen

Member
2004-09-20 11:01 pm
MN
For the opamp/buf634 circuit, look up the Meta42 amp. Or go to headwize.com.

I built the QRV07 from peranders. This is the one with the TPA6120. It is very detailed, sometimes maybe too much so. I bought it to test the 6120 and I was to lazy to lay out a board.

I'm looking at using the 6120 as a driver chip.
 
For home use i think you can skip the "TLE2426" that thing is just usefull with batteries and can't give "that" much current that you could have had.

I have build peranders ORV-04 (opa627/buf634) and it works like a charm. I'm also in the progress to make my own opa627/buf634 preamp (and it would work very well as a headphoneamp.)

The TPA i'm very interested in, if someone could give some feedback on how to make that chip as good as possible as a preamp i would be glad :)
 
Mike Gergen said:
For the opamp/buf634 circuit, look up the Meta42 amp. Or go to headwize.com.

Have you seen the PIMETA? I'm trying to understand what's going on with the 3rd ground channel... :scratch:

http://tangentsoft.net/audio/pimeta/
http://tangentsoft.net/audio/pimeta/misc/schematic1.pdf




tobias_svensk said:
For home use i think you can skip the "TLE2426" that thing is just usefull with batteries and can't give "that" much current that you could have had.

Althought this will be for home use, it'll run off batteries. Our power quality here is REALLY, REALLY bad. So far I'm thinking dual 12V panasonic lead acid batteries with a TLE2426 as the voltage divider and then the BUF634 just to make sure I'm not going to be short on current (haven't done any calcs, yet, may run multiple).

When I was still thinking about using AC, I was planning on running regulated power to the OPA637, but with batteries I can't really see a good reason too....
 

n00beR

Member
2004-03-30 9:22 am
efiF
If you were thinking of powering a pimeta like headphone amplifier from a regulated mains supply, it would definatley be a good idea to try and rework the design to get the decoupling caps closer to the supply pins.(you could even solder them directly from the pad to the pin)

However if you plan on using batteries to provide the power to your amp, I don't think the decoupling caps have to be so close. As there will be very little ripple from the batteries during normal operation.
They will of course prove more usuful, closer to the supply pins, when the battery output drops below the recomended minimum voltage for the opamp.

If you read posts over at head-fi , there is alot of people that hold the pimeta in high regard as an amplifer, and the next step up is considered to be the PPA or the M3, which is quite a jump in terms of sound quality.

But if your going to DIY I personally would move the caps closer.
It would be interesting to hear a rework design head to head witht the original.

Hope this has added to your confusion :xeye:

n00b
 

Lovan

Member
2003-10-28 8:17 pm
Sweden
Robselina: If your going to use 2x12V batteries just skip tle2426 and use the batteries to get +-12V directly.

And DO put the caps directly on the chippins! See attachment.
 

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Lovan said:
Robselina: If your going to use 2x12V batteries just skip tle2426 and use the batteries to get +-12V directly.

And DO put the caps directly on the chippins! See attachment.

Agreed on the caps, but why do you suggest using the batteries to make the virtual ground? Just convenience? current capacity?

I'm concerned about DC offset on the output but maybe I don't need to be.... :confused: