[morsel]

The PPA (PPL's Portable Amplifier) is a new headphone amplifier that PPL, Morsel, and Tangent have been working on since last fall. Over the past few years, PPL created a series of pocket headphone amplifiers using opamps and open loop buffers which were the inspiration for Apheared's #42 and the META42. The PPA incorporates a mixture of technologies from several PPL pocket amps, the META42, and new techniques such as differential output on a Eurocard format board. Testing of the first prototypes is underway and the initial results are promising. Our apologies for keeping this a secret for so long, but we wanted a reasonably detailed and substantial platform to initiate discussion.

Please visit the PPA website for more information including features, technical comments, issues, schematics and layout. This is your chance to post comments, suggestions, and requests. We look forward to hearing from you.

[size=small]http://elvencraft.com/ppa/[/size]

-Morsel, Team PPA Slave Driver

(Edit: I replaced the small layout with the full size one.)

 

[x1lexure]

OHHH NOOOO!!! Another one!!!!!

 

[puppyslugg]

Congrats, ppl, morsel, and tangent!!

 

[00940]

nice design but ... 18 AAA NiMH batteries

congratulation for the new baby anyway

 

[morsel]

Thanks.

After more people have had a chance to read the material on the PPA website I will discuss the issues list in detail.

 

[eric343]

You're all crazy...

...for not doing the full-on PPL Home design.

I'm kidding of course - I look forward to seeing Kelly's glowing review of the PPA, and finally an amplifier that can make the Sony V700s sound less than totally awful without needing EL2008s!

 

[puppyslugg]

Quote:

Originally posted by eric343 You're all crazy... ...for not doing the full-on PPL Home design.

I have to admit, I am a little disapointed it isn't a full blown ac powered amp.

 

[eric343]

It is. Even the PPL Home doesn't include a power supply IIRC, the only difference is that the Home is a discrete transistor design.

 

[morsel]

We hope the PPA will be all you ever need for home use. I'm guessing most PPAs will be built for AC operation. We have temporarily set aside the NiMH charging issues so we can focus on the amp itself.

 

[puppyslugg]

Quote:

Originally posted by morsel I'm guessing most PPAs will be built for AC operation.

I have no doubt that will be true. I just would liked to have seen what you guys would came up for the ps.

 

[kheldar]

wow.. i remember this amp.. or at least the original which i built on a breadboard. It was amazing sounding, but my board design skills weren't up to making it.

when is this one expected to be finished board wize?

I finaly convice myself to get rid of the META42, and you guys come up with something new and interesting... my poor wallet..

on the technical side, which buffer is in the lead? i know how much you dislike the burr brown one... One thing that you might want to consider is the buf634 in the to220 package, they are realy easy to stack since the pins line up in a single line. or so i found on the last amp i built.

its nice to see one thats not "ultra" small in size. room to play in =)

congrats =)

 

[Whit]

Could you increase the size of the C1 and C3 caps to 16mm so the 1000uf cerafines and blackgates would be usable? I know it sounds crazy but some people may want to use all boutique caps.

Whit

 

[morsel]

We have some power supply sketches but we need to perform more amp tests before we develop the power supply further.

Differential output is a radically different topology that eliminates the primary source of signal ground contamination by shifting responsibility for the return path from the headphones from the power supply to a ground channel. This should make the PPA far less dependent upon the power supply to sound good than the META42 or Gilmore.

We will have detailed test results for you once we resolve some testing inconsistencies. We have been using RightMark as well as some other programs that perform FFT analysis. I will guess we can get about .001% THD accuracy and .01% IMD accuracy with the new setup.

http://audio.rightmark.org/download.html

 

[dta116]

Kudos:
For the choice of a Capacitor Multiplier Power Supply.
For the OpAmp choices.
For the design implementation of a charging ckt. (if battery Powered.)
Just love the idea of ground amp !! (just don't get it yet)

Questionable:
The thought of multilayer PCB. (this is leaving the realm of DIY)
The use of Elna Caps, They are extremely difficult to obtain.

Suggestions:
Using a rotary switch for crossfeed will reduce real estate and multiple switches.
Incorporate Hi Z and Lo Z output jacks.

Love the Idea....

MANY Kudos to PPL, Morsel and Tangent.

The NEW PPA Project gurus'

 

[morsel]

Hi Whit,

We have talked about enlarging C1 but growing C3 is out of the question due to space considerations and would not do anything for the amp anyway. If we did make C1 bigger we would probably go to 18mm and have 6 of them across the top of the board. We are not sure it will actually be useful to have that much capacitance, and it might actually harm the amp, but we will know more as testing progresses.

Hey Kheldar,

The PPA is different from amps you have seen before. As I said on the website, there is no ETA on boards. We prefer the HA5002 (which is the currently implemented buffer as shown on the website) but will listen to arguments in favor of the BUF634. The HA5002 is cheaper and sounds better.