I just updated the PPA website at http://elvencraft.com/ppa/ with a small section on wiring considerations: Signal ground is input ground, not output ground. Output ground is the output of the ground channel. It exists solely to drive headphones. It is not a true ground. Do not connect signal...

DIY A/V RCA Compression Connector Cables

The 3 channel design of the M³ already gives some of the benefit of a balanced configuration. What little I have heard from balanced M³ owners suggests it is not worth the trouble and expense. Have you seen amb's new β22 project? It is a no compromise all discrete design that outspecs the...

There is no need for expensive "audiophile" banana plugs. I use the classic Pomona double banana plugs, which cost about $2-3 and come in many colors. Model MDP or 1330 are good.

DIY A/V RCA Compression Connector Cables

Thanks for the links, VC. With commercial units going for $2-3K, this is a great choice for a DIY project. The toroids Equi=Tech is selling on their website have the Plitron logo on them, btw.

Looks great, VC. Can you tell us more about the power filters you used and post a schematic? Yikes Balanced Power Supply Yikes Balanced Power Supply 2nd thread

You can make cheap audiophile quality cables comparable to expensive designer cables. F/BNC/RCA compression connectors assemble quickly and easily with common varieties of coaxial cable and grip with 360° high strength retention, resulting in more reliable and robust connections than solder...

175mA is definitely too high. Typical current draw using 2 9V batteries is around 50mA. Something must be getting warm.

I am so scatterbrained, thank goodness amb remembers these details. We Mini³ified our PINT weeks ago. I wasn't going to mention the pcb surgery, as the ferrites should also work inside the feedback loop, but perhaps not for the ground channel, since it has no feedback resistor to isolate the...

PINT Observations Posts 13 and 45

The PINT will be cheaper if you put it in a mint tin, as the Serpac H65 cases are about $13. The PINT is SMD, the Mini³ is through hole, and vaporware, I might add, as there is no telling when we will finish it. If you want something in the near future, get a PINT. If you want the PINT to sound...

splaz, if you build it with high DC offset or hook it up to a source with high DC offset, it will just sound bad, not wreck your headphones. The fear of DC offset damaging headphones is exaggerated and generally unwarranted.

Teerawit, the ferrite beads are required, not optional. Leaving them out will result in oscillation that can easily toast the opamps. This oscillation can be caused by an unterminated cable on the output, among other things. We blew over a dozen opamps testing so far, and we have a scope...

Quote: I was surprised how much hiss came from the PINT when I didn't have music playing. With lower impendance cans (I tried my PX200's, 32ohm) the hiss is very noticeable at gain of 6, almost to the point of annoyance. Tangent has suggested the presence of input capacitors on the...

Quote: A quiestion just crossed my mind, which version of the AD8397 should we use? The epad version or the "normal" one? Doesn't the pint need extra heat dissipation as the mini3? amb and I built a Mini³ified PINT using the AD8397ARDZ with EPAD. It works perfectly. We believe this...

I use Fisherman Eyewear Flip 'N' Focus 3 diopter clip on magnifying lenses on my glasses. I got them from a local drugstore for about $10.

A reply from beyerdynamic: Thank you very much for your message and your interest in our products. Concerning your request we would like to inform you that you can order DT 990 w/ 600 Ohms easily at our online shop at www.beyerdynamic.com/manufaktur Orders from the USA will be accepted. If...

I have no websites with storefronts or profit margins because I do not sell anything. I have never sold any pcbs or parts, nor have any intent to do so. I am not paid by anyone. I participate in community service projects to learn and have fun while contributing to the community.

Thanks for your reply, Nate. No idea who Rick is ranting about. Obviously it isn't me, since I design amps for fun as a community service and accept no money. Goodsound, each of the chips discussed here has benefits and liabilities. Some of these issues are rather complicated and boil down to...

Many people believe the AD8397 is a better choice for a headphone amp. The only public development being done with this chip is on Headwize. Goodsound does not have to buy anything, merely read about the work being done to see if he likes the idea of using the AD8397 instead of the TPA6120 or...

Have you seen the PINT and Mini³ projects? They use the AD8397.

Door stop, window prop, cat heater, egg beater, gerbil hut, biplane strut, its uses are only limited by your imagination. OK, another answer. Get a signal generator so you can observe sine and square wave response of amps you are testing.

I asked beyerdynamic about the availability of the new 600Ω DT990. The German office has not replied to my email yet. info@beyerdynamic.de The USA office has not heard of the new 600Ω DT990 and suggested they were only available in Europe. I pointed them to their own website: Click...

Quote: How did you calculate the VBmin and VBmax? Vbmax was measured across 2 (7 cell) fully charged Accupower NiMH 9V batteries while on C/20 trickle charge. A C/3 load was used to drain the batteries until the voltage rapidly plummeted and was disconnected at 12V. A C/5 charging...