[ozshadow]

Actually, higher impedence cans like some Senns need more voltage. Lower ones like Grados need more current than voltage.

 

[apple_tree]

Quote:

Originally Posted by ozshadow Actually, higher impedence cans like some Senns need more voltage. Lower ones like Grados need more current than voltage.

Sorry for noob question. How do I change the amp to give more current to lower impedance headphone and higher voltage to higher impedance?

 

[ATAT]

For higher impedance headphones, raise the gain (change the value of R4)

For lower impedance headphones, lower the gain and swap the buffers for beefier ones if you need even more current.. (you probably dont, but with high imp phones, buffer "sound" is less pronounced).

 

[ozshadow]

I am absolutely shocked you do not see more people trying this amp and more builders selling them, but I guess it was kindof a small volume run of boards. I know I'd like more to play with.

 

[zombieDave]

Great job, ATAT! Looks like you had the success you were looking for!

 

[khbaur330162]

I recently purchased one of these so I'll try and post impressions after I get it. From what I've read it really is a shame it doesn't get much talk. It should be noted, however, that mine won't be anything close to a standard configuration/build, really, so it may be difficult to use for comparison purposes.

I had a PPA and really liked the sound, but was recently trying to down grade. I bought the PPAS to primarily take the LaRocco's place, yet I still wanted a fairly similar, detailed and resolving sound. Mine will be configured with a somewhat enlarged hammond case, AD8058 and LM6171 opamps, LMH6321 buffers, an internal power supply to replace the charger circuit and smooth out the incoming DC (it won't run off batteries at all), RCA inputs on the back and a 1/4" headphone out on the front .

We'll see how close I can get to my LaRocco PPA in terms of SQ. I'll be using it in conjunction with a bunch of mid-fi equipment ranging from my NC555ES to the MDR-CD3000's. I should receive the amp within the next couple of weeks, but for now, I simply have high hopes!

 

[el_monkey]

Quote:

Originally Posted by khbaur330162 /img/forum/go_quote.gif I recently purchased one of these so I'll try and post impressions after I get it. From what I've read it really is a shame it doesn't get much talk. It should be noted, however, that mine won't be anything close to a standard configuration/build, really, so it may be difficult to use for comparison purposes. I had a PPA and really liked the sound, but was recently trying to down grade. I bought the PPAS to primarily take the LaRocco's place, yet I still wanted a fairly similar, detailed and resolving sound. Mine will be configured with a somewhat enlarged hammond case, AD8058 and LM6171 opamps, LMH6321 buffers, an internal power supply to replace the charger circuit and smooth out the incoming DC (it won't run off batteries at all), RCA inputs on the back and a 1/4" headphone out on the front . We'll see how close I can get to my LaRocco PPA in terms of SQ. I'll be using it in conjunction with a bunch of mid-fi equipment ranging from my NC555ES to the MDR-CD3000's. I should receive the amp within the next couple of weeks, but for now, I simply have high hopes!

I have a PPAS with a somewhat similar (AD8058/LM6171) but portable setup (shorten black metal Hammond C801 case with 5 AA batteries) that was built by ATAT. It is very similar in size to my Hornet (a little bit shorter and virtually the same width/height). With my ER4s it gives my M-modded Hornet serious competition (4th G Ipod with ALO cypto dock as my source). The PPAS has a wider soundstage and more bass. However, the bass is not quite as sharply focused as the Hornet. The highs are somewhat smoother than the Hornet. My PPAS sounds so good that I am currently debating selling my Hornet (and I am a Hornet fanboy)!

 

[khbaur330162]

Quote:

Originally Posted by el_monkey /img/forum/go_quote.gif I have a PPAS with a somewhat similar (AD8058/LM6171) but portable setup (shorten black metal Hammond C801 case with 5 AA batteries) that was built by ATAT. It is very similar in size to my Hornet (a little bit shorter and virtually the same width/height). With my ER4s it gives my M-modded Hornet serious competition (4th G Ipod with ALO cypto dock as my source). The PPAS has a wider soundstage and more bass. However, the bass is not quite as sharply focused as the Hornet. The highs are somewhat smoother than the Hornet. My PPAS sounds so good that I am currently debating selling my Hornet (and I am a Hornet fanboy)!

Well that's definitely good to hear. I certainly hope it can give my old PPA a run for its money as well.

If there was a single aspect of your PPAS that jumped out the most, what would you say it was? (i.e. treble focus, forward vocals, bass slam, etc.) I'm searching for an extremely detailed sound sig with a wide and accurate (may even be artificial to an extent) soundstage with crisp and articulate highs. Bass/lower frequencies, I've found, aren't really my thing or that big of a deal, but of course I'd like some presence and punch. If there is one thing I miss from my K701's it's their vocals. I don't want to sound redundant and say "I want my PPAS to have nice bass, vocals, and treble" because I might as well just say I want the best portable amp ever made an not have to pay for it, but, well, yea...

Only reason I'm questioning the configuration is because the AD86(1/2)0 would seem to provide more detail, however, if I could have added a single trait to my PPA when I had it, it would have been a tiny bit more warmth. Do you think this setup will fit me needs?

Thanks

__________________
Edit: ATAT has given me further insight concerning the AD8058.

Quote:

Originally Posted by ATAT As for the opamp selection, there's the LM6172 (unstable), OPA2107 (stable), and AD8058 (unstable). I would characterize the LM6172 as having soundstage, OPA2107 as having dynamics and detail, and the AD8058 as being best of both worlds, but hardest to get working. I've tweaked a bunch of resistor values to make it work. So basically though the 8058 is hard to get working, I feel its the best opamp out of the ones listed. (2107 was reccomended because it requires no tweaking, and no thinking when implementing it. I didnt want everyone else to go through the tireing process I did). Tatsu.

I'm happy to say the least. Also, it looks as though all the elctronics are done. We're just waiting on the case to come so he can engrave the faceplate and case it all up.

 

[el_monkey]

Quote:

Originally Posted by khbaur330162 /img/forum/go_quote.gif If there was a single aspect of your PPAS that jumped out the most, what would you say it was? (i.e. treble focus, forward vocals, bass slam, etc.) I'm searching for an extremely detailed sound sig with a wide and accurate (may even be artificial to an extent) soundstage with crisp and articulate highs. Bass/lower frequencies, I've found, aren't really my thing or that big of a deal, but of course I'd like some presence and punch. If there is one thing I miss from my K701's it's their vocals. I don't want to sound redundant and say "I want my PPAS to have nice bass, vocals, and treble" because I might as well just say I want the best portable amp ever made an not have to pay for it, but, well, yea... Only reason I'm questioning the configuration is because the AD86(1/2)0 would seem to provide more detail, however, if I could have added a single trait to my PPA when I had it, it would have been a tiny bit more warmth. Do you think this setup will fit me needs?

The thing that stands out the most to me is the wide soundstage. The sound tends to immerse you as your listening. The mid's and lower frequencies are somewhat pronounced resulting in a slightly darker sound than my Hornet. The Hornet is crisper in the highs. The sound is definitely warm.

 

[NelsonVandal]

That's the sound of AD8058 and LM6171. Artificially wide soundstage, lack of focus, "built in deesser", clinically clean mids and highs. I've never heard PPA or PPAS, but I'm so tempted to get one with OPA627/2107. It really sounds like my cup of tea.

 

[inconnu]

I agree with your description of the LM6171 and AD8058, except that the AD8058 differs from the former in that it has a richer tonality (especially buffered). Since tonality is vital for me, I don't dislike the AD nearly as much as I dislike the LM.

 

[NelsonVandal]

I agree about AD8058 and LM6171 Inconnu.

How do I get a PPAS? The group buy is closed. I really feel this amp was made for me. I'm jealous of you PPAS-owners.

 

[el_monkey]

I believe that PPAS boards are still available from ATAT and DieInAFire.

 

[apnk]

Whats the battery life on the PPA.

 

[n_maher]

Quote:

Originally Posted by apnk /img/forum/go_quote.gif Whats the battery life on the PPA.

It will depend on the opamp and buffer choice since they all have different current draws.