[morsel]

[size=medium]PPA v2 Project Announcement[/size]

(Trumpet Fanfare)

Team PPA present a new community service project and invite your participation.
PPA v2 replaces the Intersil HA3-5002 buffers used in PPA v1.1
with a version of PPL's discrete diamond buffer.

There is no ETA on boards.

Team PPA is Morsel, Tangent, and PPL.

[size=medium]Schematic and Layout[/size]

 

[myhui]

I am so happy to see that you have chosen to use a single pair of output transistors per channel.

Now I can sleep better.

Thanks again!

 

[doobooloo]

I have a suggestion...

Can we create extra right leads of all the C5's that extend further to accommodate for not just PCM5 caps but larger box caps of 7.5, 10, 15, 22, etc.?

Oh, I also just saw that the C2s can be made larger too.

I like the way the bass boost cap leads have been extended - perhaps the same can be applied to the C5s/C2s...

 

[bg4533]

Nice to see the addition of variable bass boost. Will there be enough room between the 2 Alps Blues to use big volume knobs? Seems like 1" knobs which are pretty standard will almost be touching each other. Any reason this pot couldn't be moved over a bit?

Any chance of getting mounting holes for a TKD pot in there?

 

[morsel]

doobooloo: The C2 caps are long and thin because they have to squeeze between the electrolytics and the output transistors, and because PPL wants them to span the distance between output transistors to provide a cross rail & channel low impedance conduit. They are 200×500mils with 400mil lead spacing. If there are real world caps that will fit 600mil lead spacing in that spot, let us know.

Why do you want larger caps for C5? If anything you could use smaller 100×300mil .1µF films instead of 1µF. On the other hand, there is room for pads at 400 & 600mils. I don't see any harm in adding them other than the fact that it will encourage people to put in more cap than needs to be there.

bg4533: With 1.15" spacing between pot shafts, there is not enough room to use 1" knobs comfortably. The problem with moving the bass boost pot over is that the space is needed for the headphone jack(s), LED, etc. There is less than 1.5" between the bass boost pot and the edge of the board. If we move it .5" to allow for 1" knobs, that leaves less than 1", and also puts the bass boost knob off center. Let's see what other people think. Sorry, no chance of TKD pads - no one uses them, and they are not compatible with Alps pads. TKD uses large solder lug tabs that would require milled slots.

 

[doobooloo]

Quote:

Why do you want larger caps for C5? If anything you could use smaller 100×300mil .1µF films instead of 1µF. On the other hand, there is room for pads at 400 & 600mils. I don't see any harm in adding them other than the fact that it will encourage people to put in more cap than needs to be there.

It's just added flexibility. If one decides to add more than is needed, that is one's choice. I personally would like more pads because I found that it's much easier to get higher quality caps (not just larger quantities) at longer lengths such as PCM7.5, PCM10, etc. rather than PCM5. It's easy to get larger (physically, not necessarily capacitance-wise) WIMAs from Mouser but the PCM5 types are sometimes not very easy to get. If there is no harm in adding them, then I think it would be a worthwhile option. IMHO.

 

[skyskraper]

wow great work guys

can't wait to see what the diy public thinks of it when theyre up and running

is there any eta on boards?

 

[Magsy]

I don't understand all the technicalities, so can someone clarifiy if PPA2 and the M³ are going to be on par with each other?

 

[ub312g0d]

because of the addition of this type of diamond buffers does it mean that OPA637's are no go in v2?

 

[steinchen]

nice build, can't wait to get the pcb in my hands

how much output-power do the buffers provide ? enough to kick the butt of K1000 ? What are the requirements for the PSU ?


Quote:

Originally Posted by ub312g0d because of the addition of this type of diamond buffers does it mean that OPA637's are no go in v2?

I don't see any reason why this should be the case. On http://elvencraft.com/ppav2/ opa637 is explecitely recommended for left and right channel (bottom of page)

 

[amb]

Quote:

Originally Posted by Magsy I don't understand all the technicalities, so can someone clarifiy if PPA2 and the M³ are going to be on par with each other?

The PPA v2 and M³ share many common design elements, the difference mainly being the output section. The PPA (including v2) is suitable for AC and battery use, due to its lower power consumption, and is designed to fit in a smaller case. The class-AB BJT diamond buffer in the PPA v2 is a good upgrade to the HA5002 chip buffer found in v1. The M³ is bigger, intended for AC power only, and employs a high-current class-A MOSFET output section.

Both are superb amplifiers. Since Morsel is involved in both projects and I am also an interested party, I would rather not stack one against the other.

Maybe you should build one of each to explore the differences.

 

[tangent]

Quote:

does it mean that OPA637's are no go in v2?

I believe ppl has gotten them to work in his prototype. I haven't tried it yet, but I will before we release it.

Quote:

Will there be enough room between the 2 Alps Blues to use big volume knobs?

There's no requirement to mount the bass boost pot on the board. It's just there for convenience; it allows you to use only two hookup wires, instead of four. If you want to mount it to the front panel such that it is farther to the left, you're free to do so.

Quote:

is there any eta on boards?

It'll be released when it's ready. This public comment period is part of qualifying for "ready".

 

[Magsy]

Quote:

Originally Posted by amb The PPA v2 and M³ share many common design elements, the difference mainly being the output section. The PPA (including v2) is suitable for AC and battery use, due to its lower power consumption, and is designed to fit in a smaller case. The class-AB BJT diamond buffer in the PPA v2 is a good upgrade to the HA5002 chip buffer found in v1. The M³ is bigger, intended for AC power only, and employs a high-current class-A MOSFET output section. Both are superb amplifiers. Since Morsel is involved in both projects and I am also an interested party, I would rather not stack one against the other. Maybe you should build one of each to explore the differences.

Thanks that covers it

Perhaps I badly phrased the question, rather than trying to determine which is best, I wanted to know if they were in the same class so to speak.
i.e. a PPA is a class up from a PIMETA and they don't directly compete.

I probably will end up building both

 

[jamont]

This looks great! Is the v2 board the same size as v1?

 

[tangent]

Quote:

wanted to know if they were in the same class so to speak.

Silly answer: No. One is class A, the other is class AB.

Good answer: Wait for independent reviews if you really care about the answer. Why would you ask for opinions from biased people?

Thinking more about it, I'm not sure anyone has heard both yet.

Quote:

Is the v2 board the same size as v1?

Hai.