[morsel]

MisterX: The PPA is not designed to accept 16mm caps, nor do we suggest you use them, nor should you have any need. Using 12.5mm (1/2") caps you can pick from quite reasonable Panasonic FC or Nichicon PW or HE and easily reach 2000-3000µF. If you want to see all the C1 slots filled, use a lower value so you don't get too much capacitance. You can also choose 8×220µF Elna Cerafines for a total of 1760µF, or if you are using an oversized case, 9×220µF Elna Cerafines for a total of 1980µF.

We switched to the inline TO92 parts because the layout works better that way, as traces may pass easily through the middle pad. Standard TO92 parts must be hand bent to fit either triangular or inline pad configurations, but machine splayed parts are difficult to unsplay without mangling the leads, so inline pads provide the best parts compatibility. Triangular TO92 parts mounted face to face can not be bent aside to read the labels without badly kinking the middle lead, whereas inline parts may be bent aside with less trauma.

aeriyn: We will let you know when we have an ETA on boards.

Voodoochile: Traces from the left pot pads passed over the top side of the board across the landing area of the sharp landing legs for the middle pot pads. In the unlikely event that the sharp landing legs puncture the silkscreen squares and solder mask, they could short against those traces, thus disabling bass boost for that channel. The bass boost pot is part of the feedback loop, not an input signal, so it didn't get ground plane coverage. M³ is done the same way. The little silkscreen squares mostly serve as reminders not to run traces from neighboring pads under them and to cover the unsightly holes in the ground plane at the volume control pot.

 

[JHouser]

Quote:

Originally Posted by morsel The bass boost pot is part of the feedback loop.

Please forgive me Morsel as i am by any means not an EE. However, Since the bass boost pot is tied into R7 does that mean if the wiper ever lifts on your pot you have a new set of barb-b-Q'ed cans? Seems a bit risky. Why not just tie into S2?

j-

 

[__redruM]

Is a schematic available?

 

[morsel]

JHouser: If you look at the layout or schematic you will see that the bass boost pot wiper is tied to the right side of the pot so that the impedance will be the value of the pot, not an open circuit, should the wiper lift. No barbecue for you.

 

[morsel]

 

[tangent]

jhouser: It may not be clear to you, but the bass boost pot is meant to replace the switch, not R7. Yes, that means the parallel resistance in the bass boost equation is complex (fixed R in parallel with log-varying R) but that is safest for the very reason you brought up.

 

[JHouser]

Quote:

Originally Posted by morsel JHouser: If you look at the layout or schematic you will see that the bass boost pot wiper is tied to the right side of the pot so that the impedance will be the value of the pot, not an open circuit, should the wiper lift. No barbecue for you.

BRILLIANT!!

j

 

[morsel]

Quote:

jhouser: It may not be clear to you, but the bass boost pot is meant to replace the switch, not R7. Yes, that means the parallel resistance in the bass boost equation is complex (fixed R in parallel with log-varying R) but that is safest for the very reason you brought up.

Nonsense, Tangent. It is perfectly safe as is. See my previous post:

Quote:

JHouser: If you look at the layout or schematic you will see that the bass boost pot wiper is tied to the right side of the pot so that the impedance will be the value of the pot, not an open circuit, should the wiper lift. No barbecue for you.

edit: Just to clarify, I would not use both the pot and R7.

 

[@sia@home]

I'm curious about the discrete diamond buffer section.

How does its performance compare to maxed Intersils? Have you compared it to any of the other diamond buffer circuits?

What is the expected cost of them, because from a quick look at mouser, they all seem really cheap parts, which should prove to make the ppa much more cost effective in the future due to not having to spend lots of money on buffering ICs.

 

[morsel]

The discrete buffers should be cheaper and draw less quiescent current than 4 HA5002 buffers per channel. Tangent and PPL are the only ones with prototypes.

 

[morsel]

Thanks for your participation. PPA v2 development is now closed. Tangent is going to order one last prototype before the production run. We will let you know when we have an ETA on the boards.

 

[MisterX]

No... thank you and the rest of team PPA for a new and exciting product.
I for one can't wait to get my hands on one.

 

[palchiu]

Bravo!
Thanks! Team PPA.

 

[doobooloo]

Awesomeness!

 

[steinchen]

big thanks team PPA

counting the days although I don't got an ETA

can't wait to heat up the soldering gun