From your outside pic, the pins agree with the orientation of my LOD.  I have the standard IOS 4.x on my ITouch 2G, so I can't vouch for that part of your system.   Have you checked the connectivity with a DVM?   Do you get connections between each pin of the dock and the correct band of...

I'm also confused by your rail-splitter check.  This check must be done with the battery installed.  As a general rule, you need to have a power source if you are going to measure voltages in a circuit.  The rail-splitter is checked by measuring voltages  between V+, V- and IG.  IG should be at...

It's very suspicious that the laptop behaves differently than your other sources.   Is there a DC offset in the signal coming out of the laptop?   Check to see if there's a DC voltage between any of the three input signals coming from the laptop. (R/L/G)   If you're hearing a...

That buffer is meant to be wrapped in a global feedback loop- that's why it's suggested as an option for the PiMeta. It's not clear how your circuit is set up in that regard. It's also not clear what you're doing about the ground, maybe that's the part of the circuit that's current starved...

From the photos, the ground channel seems to have R1 populated. AMB's specs for a unity gain ground channel involve leaving out R1. Is the gain setting of that channel intentionally non-standard?

I had three Grado SR60's cables wear out at the y-junction. The wires get stressed and eventually break inside. You can test the continuity of the headphone cable since you have the drivers open.

I'm in.

In circuit "A" the current flows from +V to the ground node. There is no return current from ground to +V, that is the segment that violates energy conservation. In circuit "B" the current flows from +V to -V. There is no return current from -V to +V, that is the segment that violates...

Quote: Originally Posted by Koyaan I. Sqatsi No, it doesn't. The "battery" in this case is the energy stored in the capacitors. I didn't bother including the rest of the power supply as it was irrelevant to the point being made. No, it doesn't. It can't. The only...

Quote: Originally Posted by Koyaan I. Sqatsi Ok, here's a little Electronics 101. Below is an illustration showing the two basic configurations. A is the passive ground configuration, B is the "active ground" configuration. The transistors represent a typical complimentary...

Quote: Originally Posted by FallenAngel 0) Would be important, ground planes are nice for noise. Quote: Originally Posted by TzeYang ^ Ground planes are harder to make right, it's not an easy application. A star ground is usually better. After reading...

Hi, I'm trying to come up with a list of features to include in my next amp. I have Grado headphones so I'm targeting my choices toward that direction. I've spent some time studying the PPA, M3 and Pimeta designs and discussions and I'm wondering how people would rank the various features of...

Hi Batistiini, Your parts list is incomplete- there don't appear to be enough resistors. Can you refer us to a picture of your schematic? It certainly looks like you have a standard CMOY from your photos. It does sound like there is something screwy going on with your ground. If the inputs...

The PiMeta v2 can be done almost entirely surface mount. The board for that is supposed to be available in mid-September.

Quote: Originally Posted by jcx Jung shows CFA op amps with gain as the high current output stage in some of his multiloop circuits - I've used the TPA6120 - not many "debugged" diy amp projects use this but the specs for audio are great using AD8397 with gain as a multiloop output...

Wow, I've just been sucked into hours of reading about discrete buffers. Just the kind of suggestions I was hoping for. Quote: Originally Posted by FallenAngel You don't need to stack LMH6321, it can already output a LOT of current. It's a considerably nicer sounding buffer than...

I am working my way up the DIY amplifier food chain. I built a CMOY, then a Mini^3, and an Apheared 47. I think the next step is to incorporate a multiloop topology- which requires a buffer. I have Grado 225i's, so I'm looking for a high current solution. LMH6321 is used in the Pimeta 2...

What happens when you power it with a single 9V battery? That would at least eliminate the power supply as the source of your distortion. I have an Apheared 47 sitting on my desk right now in plug board format, and it runs fine on a single 9V. I have also added the same rail splitter mod...

Quote: Originally Posted by Fred_fred2004 My pimeta shrunk Very nice build. I'm assuming that the traces are underneath. Very clean. Is that your own PCB layout?

Quote: Originally Posted by JamesL On the other hand, it's still capable of being a very "transportable" amp. The pimeta I built (second from left) has a pimeta board, a TREAD configured for 20v, and there was space enough for a bantam DAC if I chose to forgo the RCA jacks(not enough...

Quote: Originally Posted by holland not portable, but the Dynalo, CK2III, CTH, SOHA II, SSMH, Millett Max, are all good steps, with the CTH being the smallest but high density. Mini3, on your list is probably all that's available unless you can find a Pimeta V1 board somewhere. Don't...

Quote: Originally Posted by TzeYang You aint building nothing yet unless you've done a PPA level amplifier on perfboards and get them working in stable condition Perfboards are fun to work with. I've gone into designing PCBs for my own use so I know how boring it feels working with...

Quote: Originally Posted by JamesL If you want to stick with portable, mini3 is probably your best bet. Pint's main advantage over the mini3 is probably it's smaller size. You lose that by using a breadboard. Pimeta is a great sounding amp as well. Slightly better than the mini3...

Quote: Originally Posted by bidoux Since a SR-60 and a SR-225 are not portable can, why don't you want to go with a home amp ? Good question! I agree that the Grados are not really portable, maybe I should have said "transportable" for the amp+cans. I have several places in my...

I had a lot of fun building my first CMoy. Sounds great with Grado SR60s. I'll probably make a bunch of these for Christmas presents for my sons and brother (who all have Grados.) I'm interested in moving up the chain. I've done a lot of reading about the Headwize projects, and at Tangent's...