amb

Yes, amb.org is back online.

Dear friends, Amb.org is currently down due to a problem at the ISP. Unfortunately it is taking a long time for them to fix it. I’m very upset that it has taken so long without resolution, and it appears that it will be down for maybe another several days. The level of service I’m receiving from their customer support has been abysmal. Meanwhile please be patient as I work with the ISP to restore the connectivity. I apologize for any inconvenience this may have caused. -Ti

Thanks! Yes, this is an ambitious project involving a lot of circuitry, and firmware work too. That's why it took 1.5 years.

Hi everyone! It's been a long road from inception to reality, but the γ3 is finally out! Check its website: http://www.amb.org/audio/gamma3/ and its companion module, the γ24: http://www.amb.org/audio/gamma24/

LMAO!

Actually, the WM8741's "2Vrms" output amplitude at 0dBFS is differential, so each of the + and - outputs is half that at 1Vrms (2.83Vp-p). The chip will not clip as you stated.

I don't have any info about the ESS sabre chip (datasheets are not public, subject to NDA, which really rubs me wrong). But if the chip supports volume control via an I2C serial bus, then yes, you could do it. As for any of the other features you mention, I don't know what info is available on that board, so you'll have to do some research on your own. Some additional hardware may be required.

No dark powers. lol. Just some logic and experience. We know that your 0.47 ohm resistors are blown, so they've been subjected to overcurrents. That current goes through the MOSFETs, so there's a chance they're bad too. These MOSFETs typically fail with internal shorts. The question is, what led to this failure? Either there was an accidental short circuit (in the wiring to the amp, or from other tools/objects), or a wiring error, or a short on an amp board..., etc. So be careful after you fix the power supply, to check the sanity of the amp boards and wiring before power it back up again. It should be 10K, and there is no reason why it shouldn't measure close to that. Try removing it and measure it off-board. If it's still not right, put in a new one.

Each MOSFET has 3 pins, you set your DMM to ohms mode (if manual ranging, set to 2K ohms scale). Put the probes on any combination of two pins (there will be six possible combinations) and read the meter display. The meter might show a brief reading due to capacitor charging but should settle quickly to over-range (either "OL" or "1", depending on brand/model of DMM). If you get an actual ohms reading of several hundred ohms or less, then a MOSFET is blown. It's difficult to determine which of the two is blown while they are mounted on the board (because they are in parallel), but if one is blown then there is a good chance the other one is too, and might as well replace them both. Check all the BC546B and BC556B transistors too. With the power off, use the diode check function of your DMM to verify each of the small signal transistors. For all the BC546Bs, put the red probe on the B pin and the black probe on the C or E pins. Both measurements should give you approximately 0.6V. You should read nothing when you reverse the probes. For the BC556Bs, the procedure is the same but the probes must be reversed. The only transistors that should falsely "fail" this test are across the B-C junctions of Q8 and Q10. This is because they are purposely shorted (see the schematic), so you will get 0V reading for these. Yes, you can get replacement transistors and MOSFETs from me.

Power off and measure the resistance across any pin of the sigma22's MOSFETs (i.e., D-S, G-D, G-S). You should get very high (~infinite) readings after the meter stabilizes. If you get low ohms readings then one or both of the MOSFETs on that bank is internally shorted.

R12 and R13 are blown. Replace them and re-check the voltages. Don't connect the amp boards until you get the PSU fixed first. Then, connect the amp boards one at a time to set them up.

Not to muddy the waters, but here are some counterpoints... Both M

When ALO sells out of their existing stock, new units will have the front panel changed to the "Double Mini3" name.

KB has renamed the amp to "Double Mini3". This is reflected in the title of his Head-Fi thread and on his website. The initial batch will have "Double M^3" engraved on the front plate because they are already made and is a large investment. Subsequent production will be changed accordingly. Maybe the first batch will become collectors' items. Hah.

But ALO is not MisterX or Rockhopper, just like RSA or Headamp is not MisterX or Rockhopper. I already said that as a commercial product, ALO's pricing doesn't seem out of line. I don't know what their overhead is, but the profit is probably smaller than you think. And face it, they are a for-profit business, and there is nothing wrong with that. Whether they are "using my efforts purely for cash", well, that's a rather cynical view of the situation. Like I said, I do get a kick out of the fact that my stuff is out there being used by many people, and that's worth something to me. If I was seeking cash, I would've negotiated for some sort of payback, but you know, that's not what I am looking for.

No, I don't. ALO buys blank PCBs and some parts from me at the same price as everyone, and that's it. There is no profit sharing of any kind. I am not looking to make money from this. As you are probably aware, I put in more than I get out of it, not only financially but also in time and energy. It satisfies me enough to know that my work is out there being enjoyed by many people, whether they are DIYers or just music lovers.

To clarify what happened and to provide some background info... KB contacted me several months ago about building Mini

I really dislike negative comments about someone else's work, but the wiring to the IEC and bridge rectifier mounted on the panel look like something done by a first-time DIYer. The uninsulated AC mains wiring is not cool. I have an issue with sloppy work like like, especially in an expensive commercial product. He could have at least used some heat-shrink tubing.

Here are a few more pics. There are even more at the interim β24 website.

Just install Rockbox on the iPod (caveat: iPod Classic 6G and a few other models not supported yet, and may never be). The iPod player itself is nice, but running the Apple software ties you to the evil iTunes, proprietary file formats and cryptic, un-navigable file names and structure on the actual ipod disk. Switching to Rockbox turns the iPod into what it should have been in the first place.

The input is a single-cycle sine wave. It shows how well damped and controlled the headphone diaphragm (and associated parts) is. I can't read the Japanese to know what the test conditions are, but the outcome shows that at 100Hz, all the tested headphones exhibit some underdamped "overshoot" after the waveform stopped, with the Edition 9 being the best in this regard,. At 1KHz and 2KHz, however, the HD650 shows the best control and the least distortion and the K1000 being a very close second.

Yes the blurb on my web site about "commercial use prohibited without prior permission" is there to discourage companies from taking my work (and those who contributed) without at least some namesake recognition. That said, I do make a distinction between a commercial vendor and DIYFS people like thrice and MisterX, who have other primary jobs. They do the amp-building at night and on weekends, with a meager markup for their efforts. I don't treat them to be in the same league as, say, HeadRoom, RSA or even HeadAmp (albeit Justin is a one-man shop), and provide a great community service to those who cannot DIY. As for β24, Nelson Pass' patent and what it might imply for DIYFS, I don't know. When the design becomes more nailed down, I think it would be prudent to confer with NP again about it. At least there is one thing I am fairly sure of, is that the β24 will be rare enough that no commercial vendor, even Pass Labs, would be losing market share...

FPE has a number of fonts to choose from, and you set the size you want. If you want something that they don't have, you could always create it in some other software and save in HPGL format and then import into FPE.

I would love to, but have trouble keeping up with too many forums. Aside from headwize which remains my mainstay, head-fi and here, I also peruse several other forums periodically.

Renesas is the (not so) new owner of what was once the semiconductor arm of Hitachi. The Renesas parts Kevin refers to are the 2SK213/2SJ76 - 2SK216/2SJ79.