universal chip pre-amp project

[motherone]

Digi,

You might want to look at the Pimeta and PPA amps on tangentsoft.net, and then remove the dedicated ground channel. They're both basically the same thing -- OPamp gainstage followed by a buffer. Tangent/Phil have a lot of good info on the site regarding the headphone amps built with the nested feedback loops (I think it's mostly from Walt Jung).

That said, I think it would be nice to have the following:

1) Onboard power regulators with the option to use both dual secondaries (like a gainclone) or a center tapped (by leaving some diodes out). Maybe even something so you could have two "dual mono" preamps on the same board? LM317/337s would be fine, but discrete regulators would be nice if.

2) Spots for different sized potentiometers.. Alps RK27 and RK097?

3) Pads for SMD and DIP chips (this is pretty easy).

[sawreyrw]

digi01,

Please use CAPS where appropriate. (I'm sorry, but i couldn't help it. I see way too much of this.)

Rick

[Atilla]

Motherone, I was thinking of using Tangent's setup for a preamp, that's why I raised the question above. digi01 seems to have a reason to follow that design though. While a more detailed explanation (I'm fairly noobish so forgive me, please) would help, digi01, an experiment would be of the biggest benefit, at any rate.

[digi01]

to lgreen,motherone,
cause this is a pre-amp design,it is very different from headphone amp.
for a pre-amp,the before connections will be kinds of source(cd player,pc auduio interface,mp3,ipod),the voltage level is around 0.7V to 2V.the after connections will be kinds of resistance load(cables,pots).i assume the pre-amp will driver a long cable end with one fix resistor.
the headphone amp is inductance load,it is more complicated than pre-amp.the Pimeta and PPA amps is headphone amp,i admire they designer i hope i can design headamp after some days.


so,i think the most important thing of pre-amp is impedance matching,the second important thing is drive ability.that is why we use pre-amp in audio gear.950ohm link is a better value for pre-amp.sure 100ohm will works.
i agreed onboard,it is diy friendly but i do not like onboard psu for gain stage device.there are so many noise issue,trust me.you can check brand audio,factory evaluation board.no one use it.the gain stage at least far away from psu 120mm.
pots on the board is a good way to reduction signal route.i will consider it.but this is pre-amp balanced & unbalanced design.on board pot will no use for the balance setting.
smd&pdip combine footprint is good.the below is a test layout.

to sawreyrw,
yeah,i am working on it.

Zang

[digi01]

pic

[digi01]

the below pic is the board connections,its show standard stereo and balanced setting.in balanced mode,the chip u1 for active,u2 for passive.
this pre-amp is volume pot free design.if needed can add 10k volume pot before the input or after the output.

[digi01]

the UCP is no problem to drive 2x2 LM3886 in parallel,connections below.

to Atilla,
thanks for the inform about LME49600 buffer.i have a look on its datasheet.i have a plan of another pre-amp & headphone-amp with huge current output

[digi01]

Atilla,
i made it! this ucp v2 is a after design of the nsc's classic application.i modify it for pre-amp bettter.
i just have few samplers in stock,i hope i can find some time to test this configuration.

zang

[Atilla]

That should do it, more or less. You can afford to use a higher-value pot - 50k, maybe even 100k without any problems and you'll get even higher input impedance.

I'll get around to try to make a layout for what I'm planning one of those days as well. My first try to make a board layout

[tent]

Originally posted by digi01
Atilla,
i made it! this ucp v2 is a after design of the nsc's classic application.i modify it for pre-amp bettter.
i just have few samplers in stock,i hope i can find some time to test this configuration.

zang

sounds interesting.. would you be able to provide pcbs?

tent:wq