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  #221  
Old 08-17-2011, 12:23 PM
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Originally Posted by dfkt View Post
Make sure to put one of those on your $9.95 Hammond case: http://www.coconut-audio.com/catalog...roducts_id=148

(Yes, this is the store of Patrick82.)
Well, as PT Barnum was wont to say: "There's a sucker born every minute"

edit: OK, I just read a few HeadFi threads - some very funny stuff. I take my hat off to Patrick82 for satirising the whole audiophool thing .

Last edited by selectortone; 08-17-2011 at 12:31 PM.
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  #222  
Old 08-17-2011, 12:40 PM
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Glad if it's fake. . .

Hey measure the Fiio D5 as well so I have 5 options for a cheap DAC.
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  #223  
Old 08-17-2011, 01:43 PM
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Originally Posted by NwAvGuy View Post
It would seem that some just don't want to accept there really are people in this world trying to help others and not expecting anything besides thanks in return. Or they're willing to believe what those who do have a commercial interest tell them about people like me.
Your efforts are highly appreciated but be aware that you are threatening a whole snake oil industry with you bouts of knowledge, desire to inform, common sense, honesty and, worst of all, logic.
These are highly suspicious traits these days...

On a Patrick82 note (sorry ;-) I strongly suspect that the O2 will need at least a JUDGE power cord to perform adequately. For the background to be black enough you should consider a three stone configuration, otherwise the high end might end up being a hello kitty bit too silky smooth.

As for the RMS having an overlap with the maximum HP of the oscillation transdimensional superluminosity converter the lowered THD might help with the reception of random radio stations.
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  #224  
Old 08-17-2011, 02:41 PM
inarc inarc is offline
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NwAvGuy, I really appreciate and thank you for your effort, but I am a bit confused as to what to expect from the pure desktop version. You describe the current O2 as "well beyond the point of diminishing returns", so am I right in my assumption that the pure desktop version may cover the remaining 1 % of fringe cases and perhaps include some cosmetic or robustness enhancements, but not actually improve in an audible way?
Like others, I have no use for portable amps, so the desktop version may be the better option for me. However, I am concerned that this future version may just turn out to be more expensive without offering audible improvements and in the mean time cannibalize demand for the current O2, in reference to your "chicken and egg" problem. So should I wait for the desktop version or take the preassembled O2 board once it is available?

Last edited by inarc; 08-18-2011 at 01:09 PM.
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  #225  
Old 08-17-2011, 03:20 PM
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Originally Posted by inarc View Post
NwAvGuy, I really appreciate and thank you for your effort, but I am a bit confused as to what to expect from the pure desktop version. You describe the current O2 as "well beyond the point of diminishing returns", so am I right in my assumption that the pure desktop version may cover the remaining 1 % of fringe cases and perhaps include some cosmetic or robustness enhancements, but not actually improve in an audible way?
Like others, I have no use for portable amps, so the desktop version may be the better option for me. However, I am concerned that this future version may just turn out to be more expensive without offering audible improvements and in the mean time cannibalize demand for the current O2, in reference to you "chicken and egg" problem. So, should I wait for the desktop version or take the preassembled O2 board, once it is available?
It's a good question. The good news is you'll have plenty of time to decide as I doubt there will be any pre-assembled O2 boards before the details of the desktop version are released.

But those trying to decide if they want to order a bare O2 board now might appreciate more info. The desktop amp will mainly have ergonomic and usability advantages. Some include:
  • Easier to construct as a desktop amp with everything self contained on the PC board rather than having to panel mount jacks, the volume control, etc. and do point-to-point wiring.
  • Built-in 1/4" headphone jack (in addition to a 3.5mm jack)
  • RCA input jacks (in addition to a 3.5mm jack)
  • Most of the connections on the back for cleaner desktop use
  • A better power LED (!)
  • Perhaps a few other enhancements as well
The possible audible/performance benefits will include:
  • No input overload issue
  • A more flexible gain structure allowing better gain matching
  • The potential benefit for 1/4" headphone owners of not having to use a 1/4" to 3.5mm adapter or a hand wired panel jack (crosstalk in particular is very sensitive to even a few milliohms in the shared common connection).
  • The potential benefit of less noise by having everything on board instead of wires running around for sensitive circuitry like RCA input jacks and the volume control. It also assures proper grounding.
  • Perhaps a few other upgrades as well
Ultimately I can't say if any of the above would survive a blind listening test unless the gain is way out of whack, you're overloading the input, etc. But they're not exactly snake oil either.

The downside, as you mentioned, will likely be a slightly higher total cost. You save $11 by getting rid of the batteries--although if you're leaving them off the O2 that doesn't count. While you add roughly $20 if you need to buy the FPE back panel for the desktop amp--but that doesn't count either if you were going to do that with the O2 anyway. And some of the other upgrades may add a few dollars to the cost as well. As I said before, I don't expect it to be a dramatic difference--the price of a couple CD's at most. But that might still matter to some.

As for diluting the O2, that's true, but it's ultimately a benefit for the headphone community. Choice is a good thing. It's only an issue for commercial production where someone has to decide if the potential volume of either amp is worth it. Bare boards for both versions are easy (especially given the impressive demand in just one day). But assembled boards, kits, completed amps, etc. would require sufficient demand. Vendors are free to choose just one to offer.
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  #226  
Old 08-17-2011, 08:49 PM
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Originally Posted by NwAvGuy View Post

I don't want to de-rail what Olli is doing, but anyone is free to start a US Group Buy as well.
I'm interested in a US group buy.

A kit would be really nice.

Populated boards even better.

And a cased, populated Desktop, the cat's meow. I'll buy it from you.

USG
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  #227  
Old 08-17-2011, 09:54 PM
Soul_Est Soul_Est is offline
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Firstly, congratulations NwAvGuy on the excellently designed and documented Objective 2. I've read the three articles on it and if there is anything I can say is that you are very much like the teacher I had for telecommunications: very knowledgeable and knew exactly when the BS was there and would call those who were in the wrong, out on it. And just like him, your articles kept me intrigued from the very first sentence of the first post to the last comment on the details post.

Secondly, I can't wait to actually build the O2 and really listen to the music. Just have to get a pair of either the JVC HA-RX700 (cheap but good) or the Fisher Audio FA-003 (more expensive but similar to the RE252). Hope to pair the O2 with an IEM like the RE252 (the most sterile IEM I've owned) as well but with better ergonomics.

Thirdly, I was thinking of using the O2 with my PSX (model SPCH-1001) being used as a CD player (I know, I know, put the music on the Sansa Clip+). After reading up on NwAvGuy's review and modification of the Behringer UCA202, I figured that it would be my best bet to connect the PSX to the O2 (without modifying the original design). The reason? I prefer to have the O2 be transportable for when I'm out and about with my laptop.

Last edited by Soul_Est; 08-17-2011 at 10:15 PM.
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  #228  
Old 08-17-2011, 10:33 PM
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Thanks for all the flattering words Soul Est. I've always wanted buy a pair of Fischer Audio FA-003 closed back headphones but they've been completely unavailable in North America since last year. I have no idea if Fischer is going out of business, they just have incredibly bad distribution, or what. But it's a shame as many of their products have received great reviews. So consider yourself lucky!

I finally gave up and bought the Beyer DT770's for a more comfortable closed back headphone than my rather heavy, sweaty, ear smooshing, (but nice sounding) closed Denon AH-D2000s. I rather like the Beyers in many ways but I suspect the FA-003 is a lot more accurate.

As for DAC's, you might want to hold off a bit... I'm going to be reviewing more options soon including the $40 Asus Xonar U3 and the < $100 Creative X-Fi HD. If neither of those make the grade, I'll keep going until I find something that does. The idea is to find a reasonably portable, USB powered DAC with "no excuses" performance. The UCA202 gets close but the TI PCM2xxx DACs used in the Behringer are not exactly state-of-the-art. If I can't find anything better, the UCA202 will work, but I really want to find something closer to the O2's caliber.
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  #229  
Old 08-17-2011, 11:28 PM
Soul_Est Soul_Est is offline
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Thank you very much for the reply and your input on the DAC NwAvGuy. I really appreciate it. As for the FA-003, I had intended to get them used from a friend I know (if he still has it) and cut down on the time, effort and money spent on acquiring a brand new pair. Only thing I need to figure out now is which currently available IEM <$200.00 would have a sound signature similar to the HifiMAN RE252 (very similar to the FA-003 iirc) but without the bad ergonomics... but that's for new thread in a different part of the forum.
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  #230  
Old 08-18-2011, 04:18 AM
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Quote:
Originally Posted by NwAvGuy View Post
As for DAC's, you might want to hold off a bit... I'm going to be reviewing more options soon including the $40 Asus Xonar U3 and the < $100 Creative X-Fi HD. If neither of those make the grade, I'll keep going until I find something that does. The idea is to find a reasonably portable, USB powered DAC with "no excuses" performance. The UCA202 gets close but the TI PCM2xxx DACs used in the Behringer are not exactly state-of-the-art. If I can't find anything better, the UCA202 will work, but I really want to find something closer to the O2's caliber.
I sort of hope neither of them make the grade, as I'd love to see your take on the FiiO D3 and D5
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  #231  
Old 08-18-2011, 04:31 AM
Oliver Freeborn Oliver Freeborn is offline
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Originally Posted by upstateguy View Post
I'm interested in a US group buy.

A kit would be really nice.

Populated boards even better.

And a cased, populated Desktop, the cat's meow. I'll buy it from you.

USG
My group buy is currently on 119 boards, probably with something like half going to the US. 1 board to the US will probably cost £6. 2 costs £8.50 and 3 for £11. Not bad prices, if you are interested.
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  #232  
Old 08-18-2011, 05:06 AM
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Quote:
Originally Posted by upstateguy View Post
I'm interested in a US group buy.

A kit would be really nice.

Populated boards even better.

And a cased, populated Desktop, the cat's meow. I'll buy it from you.

USG
You'll probably have to wait for Glass Jar Audio or similar to get a full kit, as it would be a pretty big job for just one person to do on his free-time.

On the other hand you're very fortunate to be living in the US re. acquiring the the parts from Mouser with minimum hassle, and as Ollie has pointed out, shipping fees are negligible.
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  #233  
Old 08-18-2011, 06:13 AM
Oliver Freeborn Oliver Freeborn is offline
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Yes, organising kits would be extremely time consuming. In fact, if I were to offer a kit it would probably end up costing more than the fully built version I'm offering because of the amount of time it would take to organise, sort and label all of the components!

120 now in the group buy - this is proving to be an extremely popular amp. As far as I'm concerned, its popularity will only increase as amp is reviewed in the real world.
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  #234  
Old 08-18-2011, 07:12 AM
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^Oliver, will you post a link on this thread to the complete build? Do you have a price estimate yet?
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  #235  
Old 08-18-2011, 09:19 AM
Oliver Freeborn Oliver Freeborn is offline
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I don't know if I'm overstepping the mark by saying that you can find the info on my website http://epiphany-acoustics.co.uk/7.html (if I am, then mods, please accept my apologies and edit as necessary). The page will be updated over the next few days and weeks as I refine it and add more details as they become available.

I can't see the price going over £100. If orders are high enough, there is scope to knock down the price a bit.
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  #236  
Old 08-18-2011, 11:22 AM
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Originally Posted by Limp View Post
I sort of hope neither of them make the grade, as I'd love to see your take on the FiiO D3 and D5
The Asus Xonar U3 and Creative Sound Blaster X-Fi HD (a.k.a. Sound Blaster Digital Music Premium HD) will probably not support a sampling rate of 44.1 kHz natively. Internal resampling will probably worsen sound quality.

Further possible contenders:
Audiotrak Prodigy Cube
Audiotrak Maya U5
ESI Dr. DAC nano / JAVS nanoS (May have an uneven frequency response, according to some RMAA measurements.)
JAVS nanoV
(FiiO D5)

May not work with generic drivers:
Musiland Monitor 01 mini
Musiland Monitor 01 US

More obscure ones:
XiangSheng DA-04A
Miditech / Midiplus Audiolink Pro

Will probably be too expensive and may not work with generic drivers:
Asus Xonar Essence One

Last edited by inarc; 08-19-2011 at 03:47 PM.
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  #237  
Old 08-18-2011, 11:52 AM
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hello, good day, is this possible? ive created a schematic based on the given and modified the battery and power supply area so that i can select from battery to DC. i know there are better solutions, but this is one of my options (enclosed in blue):



for the parts, i have substituted the items because my library is limited to guitar effects components. so as of now, looking at the opamps, it is the presented physically rather than the schematic way.
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  #238  
Old 08-18-2011, 12:30 PM
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Originally Posted by Limp View Post
I sort of hope neither of them make the grade, as I'd love to see your take on the FiiO D3 and D5
The D3 isn't USB so it's worthless for a lot of applications (and don't even get me started on USB -> S/PDIF converters!). And, AFAIK, the D5 isn't available yet in the USA? Does anyone know what the price will be?
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  #239  
Old 08-18-2011, 12:34 PM
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Quote:
Originally Posted by jmwreck View Post
hello, good day, is this possible? ive created a schematic based on the given and modified the battery and power supply area so that i can select from battery to DC. i know there are better solutions, but this is one of my options (enclosed in blue):
I'm not clear on why you want to add the switch? If you unplug the AC power the O2 runs from battery. If you plug in the AC power, even with the batteries in place, it runs on AC power (and also charges the batteries). So it automatically switches by itself.
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  #240  
Old 08-18-2011, 12:45 PM
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Quote:
Originally Posted by inarc View Post
The Asus Xonar U3 and Creative Sound Blaster X-Fi HD (a.k.a. Sound Blaster Digital Music Premium HD) will probably not support a sampling rate of 44.1 kHz natively. Internal resampling will probably worsen sound quality.

Further possible contenders: ...
Thanks for the list! I'll explore those. But as far as "re-sampling" that's a complex, and controversial, topic. One can argue all one bit delta-sigma DACs (virtually all DACs these days) "re-sample" as they all operate at a vastly higher clock rate internally.

I doubt inexpensive USB DACs are going to have a standalone DSP or ASRC (Async Sample Rate Converter) chip. So you're left with the DAC/CODEC chip itself. And it will very likely be fed the native USB 44 Khz bitstream. Creative is big enough they do their own custom chips so I'm not sure what all they might do. But the $40 Xonar likely uses an off-the-shelf part.

What happens inside the DAC chip depends on how it was designed. But, for obvious reasons, most are designed to perform well with a 44 Khz input. How the overclocking, filtering, etc. is done is managed internally in the DAC. Even the much loved flagship Wolfson DACs have to "convert" the bit stream as part of their oversampling process.

And there are ways to explore the "fringe" performance of a DAC with the dScope to determine if there are problems with the sampling rate conversions, filtering, etc. Put another way, if it's bad enough to sound bad it would almost certainly show up in the measurements.

PS - Sorry for not using Multi-Quote!
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