I must agree, im not keen on the look of the mobile line, I would probably be much happier with it if the jacks werent mounted how they are (angled on corners) and instead were mounted conventionally on the front......
Agreed. It is too difficult to use one of those units portably in a camera bag when the input jacks are on the back. I have the same gripe with the D1.
With my 2006 MicroDAC, it can stand on end in a smallish camera case and it's easier to use on the go.
Agreed about the layout, but I don't feel it's bad enough to make them unusable. Just a tad awkward at times.
Things I'd prefer changed about the Bithead:
-more grip in the mini jacks (seriously my phones don't need much of a yank at all to pop out, though maybe less wear and tear is a good thing)
-a "very high" gain setting. Just kidding. Full volume on high gain over my HD280s is pushing the hearing-damage envelope quite well enough. I do find low gain inadequate for most use as my ideal listening volume on most cans I've tried is only reachable if I've got the gain on high.
__________________
Team wears full-sized cans in public.
Moogoo's appropriate lyrics of the week:
"Lullaby of the crescent moon took you
Mesmerized, its kaleidoscopic face
Granted you a hollow stare
Another soul within the divine herd"
-Opeth, Black Rose Immortal
Equipment (in no particular order):
-Grado SR-325is
-Grado SR-80s
-Senn HD-280 Pro (first real cans)
-Vintage Koss PRO 4AAA (just got 'em working again!)
-Headroom Total Bithead
-Headroom Micro Amp
I apologize in advance if this was already mentioned in the thread, but:
I think it would be really cool to have some more technical information about the non-headphone products you carry on your website. I really like the 4 graphs available for the headphones and it would be neat to have this same kind of information about amps, DACs and such available online. Stuff like frequency response, THD, etc..
I didn't manage to read through this whole thread so maybe someone has suggested the following things already, but:
1) I think you should make the total bithead support both USB and SP/DIF input. Right now that requires your much more cumbersome and expensive micro dac setup. There are some other converters more resembling the total bithead that do both, so yours should too.
2) My total bithead seems to pick up some 60 cycle hum when I use it plugged into my laptop computer (Thinkpad T61) when the computer is on ac power. It doesn't happen with my officemate's Macbook Pro. So, there's not enough filtering inside the Total Bithead, it sounds like. I hope you can fix this. This is with the Total Bithead running on USB power, I haven't yet tried it on AAA cells.
4. It's annoying that you recommend against rechargeable AAA's in the Total Bithead, indicating that the internal voltage is marginal. Who wants to keep throwing away batteries? Please fix this, by modifying the circuit to use lower voltage, or adding a dc-dc stepup converter inside, or running on more batteries (six rechargeable aaa's would be fine, or if necessary a 7.4 volt standard camcorder pack like Sound Devices uses).
5) Finally and somewhat more ambitiously, there is a crying need for someone to make a no-nonsense audiophile DAP. The big merchandisers are all making "multimedia" players, even Neuros has lost interest in audio, so I think you're elected. When you think about it, a DAP (with the video junk thankfully removed) is nothing but a DAC/headphone amp whose input source is internal storage instead of a computer port. Yeah that means adding a microprocessor and some controls and some software, but the software is already done (Rockbox) and the other stuff is off the shelf. Your DAP would basically be a Total Bithead with an SDHC slot (better yet, 2 slots, one of them internal), a simple monochrome LCD display, and a microprocessor running Rockbox and feeding the DAC. Of course it should still be useable as a computer peripheral, and it should support SPDIF output. It could even have an accessory hard drive "backpack" containing a 2.5" SATA laptop drive (500gb available today), that would use the flash memory as a cache so the HD would almost never spin. If you build this, I think you will be the king of head-fi.
I didn't manage to read through this whole thread so maybe someone has suggested the following things already, but:
1) I think you should make the total bithead support both USB and SP/DIF input. Right now that requires your much more cumbersome and expensive micro dac setup. There are some other converters more resembling the total bithead that do both, so yours should too.
There is no easy way to change one of the input jacks to spdif. The whole board and enclosure would have to be revised.
Quote:
Originally Posted by paulr
2) My total bithead seems to pick up some 60 cycle hum when I use it plugged into my laptop computer (Thinkpad T61) when the computer is on ac power. It doesn't happen with my officemate's Macbook Pro. So, there's not enough filtering inside the Total Bithead, it sounds like. I hope you can fix this. This is with the Total Bithead running on USB power, I haven't yet tried it on AAA cells.
I have thinkpad T43p and X41 tablet and have no such issues but I have heard of this problem. I wonder what could be causing it.
Quote:
Originally Posted by paulr
4. It's annoying that you recommend against rechargeable AAA's in the Total Bithead, indicating that the internal voltage is marginal. Who wants to keep throwing away batteries? Please fix this, by modifying the circuit to use lower voltage, or adding a dc-dc stepup converter inside, or running on more batteries (six rechargeable aaa's would be fine, or if necessary a 7.4 volt standard camcorder pack like Sound Devices uses).
The 6v average provided by alkalines is already pretty thin for the ad8397. 4.8 volts provided by the disposables is not too fun and the buffer's ability drops some. I think the best solution would be dc-dc converter since usb's 5volt shared between the digital and analog circuitry isn't optimal. I suggest energizer lithium batteries. They give the full 6 volts for 4 cells, last for more than a couple hundred hours without steady drop in voltage, and are much lighter in weight than either alkaline or nimh. The energizer lithiums also measured marginally better than running off usb power.
Quote:
Originally Posted by paulr
5) Finally and somewhat more ambitiously, there is a crying need for someone to make a no-nonsense audiophile DAP. The big merchandisers are all making "multimedia" players, even Neuros has lost interest in audio, so I think you're elected. When you think about it, a DAP (with the video junk thankfully removed) is nothing but a DAC/headphone amp whose input source is internal storage instead of a computer port. Yeah that means adding a microprocessor and some controls and some software, but the software is already done (Rockbox) and the other stuff is off the shelf. Your DAP would basically be a Total Bithead with an SDHC slot (better yet, 2 slots, one of them internal), a simple monochrome LCD display, and a microprocessor running Rockbox and feeding the DAC. Of course it should still be useable as a computer peripheral, and it should support SPDIF output. It could even have an accessory hard drive "backpack" containing a 2.5" SATA laptop drive (500gb available today), that would use the flash memory as a cache so the HD would almost never spin. If you build this, I think you will be the king of head-fi.
That's no small deed. I hope to see something like that one day.
__________________ If it sounds good to you, . . . . . it may still suck, no matter what you think. People who understand the design and quality of your equipment laugh at you behind your back.
Don't pretend to understand electronics. Enlightened groups secretly laugh at your fatuousness.
Speaking in a magisterial, patronizing, or sycophantic fashion publicly just because you own seemingly upscale equipment is an amusing phenomenon. Amusing for those who laugh at you behind your back.
There is no easy way to change one of the input jacks to spdif. The whole board and enclosure would have to be revised.
Yes, clearly it would be a substantial update, not just adding a connector, but such updates are normal as technology marches forward.
Quote:
I have thinkpad T43p and X41 tablet and have no such issues but I have heard of this problem. I wonder what could be causing it.
I think it is the noise cancellation circuit in the Peltor ANC headphones being unusually sensitive to 60 cycle leakage. It also happens with my Asus EEE PC. I suppose I could try it on some other laptops around the office as well. I tried it on a Macbook Pro because Macintoshes are supposed to have better audio than most laptops, and sure enough there was no hum.
Quote:
The 6v average provided by alkalines is already pretty thin for the ad8397. 4.8 volts provided by the disposables is not too fun and the buffer's ability drops some. I think the best solution would be dc-dc converter since usb's 5volt shared between the digital and analog circuitry isn't optimal. I suggest energizer lithium batteries. They give the full 6 volts for 4 cells, last for more than a couple hundred hours without steady drop in voltage, and are much lighter in weight than either alkaline or nimh. The energizer lithiums also measured marginally better than running off usb power.
Those lithium cells are ridiculously expensive! And alkalines are 1.5v when they're brand new, but a substantial amount of their discharge curve is below 1.25v, so it begins to sound like the Total Bithead isn't all that well designed, if its performance is suboptimal at 5 volts. What about using a 9 volt battery (or 7.2 volt rechargeable)? Will that blow it up or anything?
Quote:
(re: DAP) That's no small deed. I hope to see something like that one day.
Just kidding. Full volume on high gain over my HD280s is pushing the hearing-damage envelope quite well enough. 
I do find low gain inadequate for most use as my ideal listening volume on most cans I've tried is only reachable if I've got the gain on high.
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