[peranders]

If you mean the link above, that's correct because I haven't got the time to upload anything yet, tomorrow or this weekend I'll hope. EDIT: fixed now!

Anyway, the pcb will be rather cute and I can't wait to test it.

 

[peranders]

I have uploaded some documentation now.
Schematics can be found above and the layout here. The groundplane isn't shown, which are on both sides.

http://www.sjostromaudio.com/hifi_fi...0layout_cp.pdf
http://www.sjostromaudio.com/hifi_fi...0layout_cl.pdf
http://www.sjostromaudio.com/hifi_fi...0layout_sl.pdf

I notice also that the interest for a group buy is very much zero so I'll call this off.

 

[ppl]

Why the second stage is operated inverting. since the first stage is non inverting the resultant output of this amp will be 180 deg out of phase with its input since absolute phase is important to some and there is no way to reverse that since the polarity of the RCA input and the headphone output. Just a thought. Otherwise quite a nice idea

 

[peranders]

I wanted a high impedance buffer AND the lowest distortion possible from the TPA6120, therefore I chose the inverting mode for the TPA6120. I'm fully aware of that this amp is an inverting amp without any possibilities to change this. Fortunately I'm not a believer of the absolute phase.

I must add though, that it's rather easy to convert the TPA6120 to non-inverting mode.

Partslist can be download now. Please notice that I have changed the design a bit so download the other files again so they match the partslist.
http://www.sjostromaudio.com/hifi_fi...qrv07r0xls.zip

 

[ppl]

thanks i was just woundering why you made the second stage inverting. I know that due to no Common mode capacitence in inverting config's as opposed to non inverting that THD will be lower.
as far as absolute phase is concerned your cxorrect its really somthing some people obsess way much over. I sometimes think i can tell the difference using thew phase switch on Grado HP-1 (Not Mine BTW) and just when i think i haear somthing i find that it is not consistent, besides how can we know that absolute phase is maintained throughtout the recording chain.
BTW i was not being critical of your design just asking a few questions

 

[peranders]

Altough the interest for a group buy was absolutely zero here I have at least ordered prototype pcb's.

 

[jamont]

Show us some pictures of the boards when they arrive.

 

[peranders]

What do you think?

 

[doobooloo]

Oooh, that looks very nice. As always, with all of your beautiful designs.

Just wondering - how much will a set cost? How much with all the parts?

Thanks!

 

[eric343]

Oh, wow!

I may have to pull my hot-air SMD station out of storage.

That's quite a project, though... how much for a full kit?

 

[00940]

I'm curious. What exactly are those points under the powerpad ? How do you solder it ?

 

[Garbz]

These points simply link the top of the board (power pad) to the copper on the bottom thermally. Ideally it should be wave soldiered to soldier the power pad directly to the heatsink.

When i build my circuit i intend to use some themal epox resin to bond the powerpad to the surface and then only soldier the legs.

Btw peranders, the picture isn't detailed enough so I may be wrong, but on the bottom of the board it doesn't look like thepowerpad legs are directly touching the groundplane. I believe the datasheet said to put the vias directly in contact with the board and not have that little star that is used in a lot of groundplanes to make soldiering easier.

 

[intlplby]

i noticed it said maid on a macintosh.... what program are you using for pcb layout

 

[peranders]

Quote:

Originally Posted by eric343 Oh, wow! I may have to pull my hot-air SMD station out of storage. That's quite a project, though... how much for a full kit?

Thank you guys!

It's not particular expensive. Just download the partslist and calculate. (You could always get samples from texas and AD.

 

[peranders]

Quote:

Originally Posted by intlplby i noticed it said maid on a macintosh.... what program are you using for pcb layout

RUN Electronic Design System, a german software in the 12000 UDS region...but I did not pay that