discrepancy between PPA PCB v1.1A and schematic!

[aaa 0]

As I was designing the layout for my own PPA clone, I found a discrepancy between the PPA PCB v1.1A and schematic from tangentsoft website.

 

 

This is the PCB v1.1A

 

 

 

this is part of the original schematic from http://www.tangentsoft.net/audio/ppa/amp/misc/schematic6.pdf

 

 

 

this is a schematic I drawed from reading the PCB picture

[bpribadi 0]

Wow, is this the first time people found about it? The original schematic should be the right one.

[heady 0]

bpribadi, what is the purpose of R8 anyway?

[bpribadi 0]

RC filter, to improve ripple and noise filtering (but reduce current discharge speed).

[aaa 0]

written it to Tangent.

Lets wait for his reply

[aaa 0]

The PCB is the right one.

Tangent has already updated the schematic6.pdf file on his website to schematic7.pdf.

[heady 0]

aaa, well done. Been trying to find time to understand the schematic. Am planning a lower end version of PPA. I am skipping the TLEs for each opamp, just one for all 3 opamp.

 

[aaa 0]

I have spent more than 100 hours in the last half year looking at the PCB layout, the schematic, and datasheets of verious components...

 

But why would you be stingy on TLEs?

Does 1 TLE make the design easier?

Cost wise TLE2426 is $3.50 each at federal component, not that high considering the over all cost of PPA.

Edited October 25, 2004 by aaa

[heady 0]

aaa, not the cost, the space and also my skill level. I am working my way up slowly from easier to more difficult. I just finished my pimeta which actually sounds fabulous but hands itchy to do something to fill the casings I bought. I have a rather short casing which I can use to make a portable PPA clone but with less parts, so that's what I will do first. I am , always do wacky things. Fun lah.

 

Wow, you are really studying, man. BTW, will you get the Glassman diamond buffer, it is US$40 for all three channel but you have to do your own soldering. Slightly cheaper than buying 4 HA5002 per channel.

Edited October 25, 2004 by heady

[aaa 0]

my current design is 4 HA-5002 per channel

I'm staying away from discrete components because I try to keep things simple.

If using discrete components the design will be more complex and I don't know how many hours will it take me on reading (due to my empty background about electronics), the end result will be a project never ending.

further more if headroom's MAX/BLOCKHEAD can make do with 2 HA-5002/channel, I don't see why It is not good enough for me.

[heady 0]

aaa - there is an opinion among some of the people in the diy community who feels 2 buffers per channel is optimum. I don't know myself as I have listened to amps with one buffer only.

 

Will you be using perf board or doing your own etched circuit board?

[aaa 0]

I'm using the very common 100X250mm perf board from SLT.