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
Anyone have any thoughts on this idea?
Thanks!
Rob
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
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
Regards,
Andrew
Upupa Epops said:Rob, look at pages of peranders. There you find many excelent headphone amps...
Is this who you're talking about?
http://home.swipnet.se/~w-50719/hifi/
Seems like a good link!
Upupa Epops said:Correct
Yea, that TPA6120 looks interesting. I've got some samples on the way so I can look at them in person and decide how scared I am of their package but I think soldering them will definitely be out of my league!
Fortunately I do know a few good electrical technicians here at work who may help me out 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.
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
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:
Have you seen the PIMETA? I'm trying to understand what's going on with the 3rd ground channel...
http://tangentsoft.net/audio/pimeta/
http://tangentsoft.net/audio/pimeta/misc/schematic1.pdf
tobias_svensk said:
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....
If you going for the pimeta i would suggest you to do better with the caps, n00ber and i have been pushing the caps as close as possible to the OP's supply pins
http://www.diyaudio.com/forums/attachment.php?s=&postid=643518&stamp=1116272644
http://www.ettnet.se/~tobias/diy/opabuf/opabufwoic.jpg
I can't say that i've tried it but the PCB is on it's way soon, but common sense says that it "should" be good to have the caps as close as possible. In that Pimeta board they are not close
http://www.diyaudio.com/forums/attachment.php?s=&postid=643518&stamp=1116272644
http://www.ettnet.se/~tobias/diy/opabuf/opabufwoic.jpg
I can't say that i've tried it but the PCB is on it's way soon, but common sense says that it "should" be good to have the caps as close as possible. In that Pimeta board they are not close
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
n00b
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
n00b
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