[mikeaj]

Maybe you should emphasize that you have the upgraded adapters recommended (by the designer) for power-hungry headphones (that others such as JDSLabs do not provide).
 
Or consider selling them separately, if that would help?  Probably not, if you want to get rid of both.  Possibly also just take a larger price hit and reduce the price, as most people prefer options from other sources unless there is a significant discount to be had via sale/trade forums.  Do threads usually get that many views without any action?  I think it's the price, really.  For example, Mayflower Electronics offers O2 + ODAC combo in one box for $250 shipped.  
 
You might as well list what the gains are, as the build doesn't look standard (different faceplate than some are used to).  Maybe offer to change them if you have different resistors handy.
 
Good luck selling them.  

 

[lorriman]

Btw, I personally have nothing against JDS Labs but they should offer much more info about what gain is suitable with and without ODAC (and stop offer 6.5x configuration when you order an amp with ODAC installed inside), offer more than 1x/2.5x/6.5x settings to choose from, they should also offer WAU16-400 or 16-1000 instead of not completely ideal WAU 12-200 and I would also prefer to have more options to choose from in terms of appearance, pricing is also quite high... Plenty things to improve.

The pricing is low. A proper business costing would not have resulted in such low-cost, hand-built amps (excecpt maybe from China). The designers intent was a for a cheap self-build, but from a business perspective the prices offered by the sellers is a bargain.

To repeat for the hundredth time, and before anyone else gets stung by your advice: 6.5x is needed if anyone (and especially loud listeners) has any intention of using a portable player as a source, or uses significant EQ. The presence of the ODAC is irrelevent to this unless you really intend to never, ever use an external source; but why lose that flexibility. Even then, I have used the ODAC on a win7 computer that for whatever reason had very low max system volume; I needed 6.5x gain.

I strongly advise users to avoid 1x 2.5x O2's (or clipping the 6.5x resistors to get the same).

 

[RustA]

Quote:

The pricing is low. A proper business costing would not have resulted in such low-cost, hand-built amps (excecpt maybe from China). The designers intent was a for a cheap self-build, but from a business perspective the prices offered by the sellers is a bargain.

To repeat for the hundredth time, and before anyone else gets stung by your advice: 6.5x is needed if anyone (and especially loud listeners) has any intention of using a portable player as a source, or uses significant EQ. The presence of the ODAC is irrelevent to this unless you really intend to never, ever use an external source; but why lose that flexibility. Even then, I have used the ODAC on a win7 computer that for whatever reason had very low max system volume; I needed 6.5x gain.

I strongly advise users to avoid 1x 2.5x O2's (or clipping the 6.5x resistors to get the same).

 
1) Have a look at Mayflower electronics - US company cooperating with JDS Labs with significantly lower prices and as well significantly more customising options.
 
2) 6.5x is useless, I know it myself, I own a unit with SIP adapters and can choose my gain configuration to whatever value I want anytime.
 
a) With ODAC - Even if you use replaygain along with EQing, you won't be using anything above 2.5x unless the very extreme cases. I've tried several headphones, flagships or cheaper...
 
b) Without ODAC - Here it actually is possible to use higher gain in unusual conditions. But 6.5x? Use 1x and 4x or something like that. The rough guideline on the author's website is actually inaccurate.
 
You will get the very best performance from your amp only in 1x gain mode, its possible to find clues on DIY forums... I've carefully compared different gains and yes, with higher gain than ideal, you get subtle distortion and lost the ultimate transparency + you can get low-level hissing and other problems that some people experience. I see no reason why not go for the best.

 

[lorriman]

1) Have a look at Mayflower electronics - US company cooperating with JDS Labs with significantly lower prices and as well significantly more customising options.

Then they may be doing it merely for the joy of it. Once you've totted up manual labour, posting and admin costs, the JDS O2 is well under-priced.

2) 6.5x is useless, I know it myself, I own a unit with SIP adapters and can choose my gain configuration to whatever value I want anytime.

It's useless to you. And I'm not seeing an argument here, merely an assertion. I've already justified myself fully and you haven't sought to address what I wrote but just repeat your own listening requirements.

b) Without ODAC - Here it actually is possible to use higher gain in unusual conditions. But 6.5x? Use 1x and 4x or something like that. The rough guideline on the author's website is actually inaccurate.

What unusual conditions? Using a portable player, with EQ and/or a high ohm headphone is not unusual. The designers recommendation was carefully thought through as is everything he does.

You will get the very best performance from your amp only in 1x gain mode, its possible to find clues on DIY forums... I've carefully compared different gains and yes, with higher gain than ideal, you get subtle distortion and lost the ultimate transparency + you can get low-level hissing and other problems that some people experience. I see no reason why not go for the best.

The distortion at high gain shouldn't be possible to hear unless you have poor headphones generating their own distortion. As for noise, that will most likely be your source or an inappropriate volume level for a very sensitive headphone. The 'best performance at 1x' is academic. The real reason for 1x is to get the volume pot past 9 and safely out of the way of channel imbalance (where your source is 16bit an must be run at max digital volume). As it happens, for loud listeners 9 can be just fine with etymotics (EQ'd for more bass) and already past audible channel imbalance. So even that's often not needed. For most, setting the source's volume lower (assuming 24bit) is just fine to avoid the need for 'the snip' to get 1x.

A 1x/6.5x O2 is a fine compromise (and ipod users are more likely than most to need 6.5x). 1x/2.5x is unnecessarily limiting your options.

 

[MrMateoHead]

Gain is Gain - Its about matching an input signal to the output signal.
 
With 2v RMS, I rarely hit more than 12 O'Clock on the O2.
With 1V RMS, I easily make it to the right of 12. With some High Dynamic Range recordings, I have reached max volume. At 6.5X, this would not be possible.
 
With Cell Phones, Mp3 players, and other bad sources, I need 6.5X and a good twist of the dial.
 
No distortion, no noise. The O2 is good to the point where, when I do hear noise, I know it is within the recording. The flexibility is well worth it.
 
I have a car radio which does 4V max from pre-outs. As-tested, the "fronts" actually clip after about 3V, while the Subwoofer channel can reach 4V. Both channels clip way before the volume dial is maxed (a 'feature' I despise) - though I swear ambient temp and other factors give and take away my headroom. So, for the first time ever, I have an amp running at almost maximum gain. Meanwhile, source volume of the Radio, CD, USB, and AUX IN are all different. Without a question, very high gain is the cost of trying to ensure that the amp is stressed out before the pre-outs are in that system. It is not ideal in terms of maximizing 'signal to noise', but with good equipment (and I have good equipment), there is no audible penalty for running higher gain.

 

[cel4145]

1) Have a look at Mayflower electronics - US company cooperating with JDS Labs with significantly lower prices and as well significantly more customising options.

That description is kind of a stretch. Mayflower is more of a DIYer Ebay seller who has his own website and sells from there, too, an electrical engineering student who says he is borrowing his college's equipment to test his products. He's obviously buying the DIY kits and components from JDS Labs, as anyone else can do.

Not trying to cast doubts on his ability to put together customized ODAC/O2 builds. But Mayflower is a obviously a one man operation who will work for very cheap. A little bit different from JDS Labs, which is a company that not not only has parts manufactured to build the ODAC/O2, but also designs it's own headphone amps.

2) 6.5x is useless, I know it myself, I own a unit with SIP adapters and can choose my gain configuration to whatever value I want anytime.

The O2 amplifier design is available under a Creative Commons Attribution-NoDerivs 3.0 Unported License. So this discussion is moot. It would be illegal and unethical for a company like JDS Labs that designs their products, too, to violate the IP rights of another designer.

 

[RustA]

Quoteosted by lorriman /img/forum/go_quote.gif

The distortion at high gain shouldn't be possible to hear unless you have poor headphones generating their own distortion. As for noise, that will most likely be your source or an inappropriate volume level for a very sensitive headphone.

 
There are several people who reported problems with low-level hiss... Even the author himself speaks about it on the website. O2 is not dead silent unless you use 1x gain, or low sensitivity headphones, in my experience with two different amps.
 
I hope you won't call HD800, D7000 or LCD-2 "poor" headphones. And still I have heard subtle distortion on higher gain configurations - very subtle but if you want the highest level of transparency, you cannot ignore it. As I said, the cleanest signal with dead-silent background with all headphones (including IEMs) is most probably only possible to achieve with unity gain.
 
There are other problems with higher gain - low-level channel imbalance, scratchy sound when manipulating with the volume knob... I am not the one who reported this here, other people experienced it and I know what they are talking about since this is not only a case of O2 or DIY stuff. ,-)
 
But it's up to you, boys, whatever floats your boat... I have my own highly customised unit and I am very happy with the performance. It's still the same neutral FR but with higher level of transparency + other useful features.
 
Maybe someone will find my contribution useful... But for now, unsubbed.

 

[lorriman]

There are several people who reported problems with low-level hiss... Even the author himself speaks about it on the website. O2 is not dead silent unless you use 1x gain, or low sensitivity headphones, in my experience with two different amps.

Well, yes you can get hiss, but at absurd volume levels with ultra-sensitive iems. If windows suddenly pinged you, you would end up with no eardrums and possibly no head.

I hope you won't call HD800, D7000 or LCD-2 "poor" headphones. And still I have heard subtle distortion on higher gain configurations - very subtle but if you want the highest level of transparency, you cannot ignore it. As I said, the cleanest signal with dead-silent background with all headphones (including IEMs) is most probably only possible to achieve with unity gain.

I don't mean to sound arrogant, but you are almost certainly not hearing anything. As you say "very subtle", which is just a side-step from 'expectation bias'. The numbers just don't show any distortion that anyone is going to hear even at max volume before clipping even with the HD800. Unless I'm reading the charts wrong. The designer did a top job, and his choice of default max gain doesn't compromise the audio in any meaningful way. Or perhaps you have a faulty O2. In any case an ABX/DBT is called for to genuinely verify this.

There are other problems with higher gain - low-level channel imbalance, scratchy sound when manipulating with the volume knob... I am not the one who reported this here, other people experienced it and I know what they are talking about since this is not only a case of O2 or DIY stuff. ,-)

These aren't high gain issues. I have them myself, and they don't affect the actual audio.

 

[mayflower1]

Quote:

That description is kind of a stretch. Mayflower is more of a DIYer Ebay seller who has his own website and sells from there, too, an electrical engineering student who says he is borrowing his college's equipment to test his products. He's obviously buying the DIY kits and components from JDS Labs, as anyone else can do.

Not trying to cast doubts on his ability to put together customized ODAC/O2 builds. But Mayflower is a obviously a one man operation who will work for very cheap. A little bit different from JDS Labs, which is a company that not not only has parts manufactured to build the ODAC/O2, but also designs it's own headphone amps.
The O2 amplifier design is available under a Creative Commons Attribution-NoDerivs 3.0 Unported License. So this discussion is moot. It would be illegal and unethical for a company like JDS Labs that designs their products, too, to violate the IP rights of another designer.

 
This is Tyler, From Mayflower Electronics. I have tried to not have an account on here for a long time, but I must respond to this.
 
I am not "obviously" a one man operation who will work for cheap. I have employee's on and off depending on the work needed at the time.
 
I am NOT by any means buying any "kits" from anyone. I buy my components myself from mouser.com. The only thing I buy from JDS is his boards because buying them myself would costs thousands of dollars. I am not "barrowing" anything from my college. When I have a board that needs advanced troubleshooting, I use the scope at my test-bench at school. Please don't assume anything.

 

[cel4145]

This is Tyler, From Mayflower Electronics. I have tried to not have an account on here for a long time, but I must respond to this.

I am not "obviously" a one man operation who will work for cheap. I have employee's on and off depending on the work needed at the time.

I am NOT by any means buying any "kits" from anyone. I buy my components myself from mouser.com. The only thing I buy from JDS is his boards because buying them myself would costs thousands of dollars. I am not "barrowing" anything from my college. When I have a board that needs advanced troubleshooting, I use the scope at my test-bench at school. Please don't assume anything.

My apologies for assuming you were buying equipment from JDS Labs other than the faceplates and boards.

But you do say on your website that you are a college student, that you are the one doing the building, and that you are using your school's equipment, with the implication that you are testing every amp to make sure that it works properly:

It is really that good! I am a electrical engineering student with access to our lab which has $20k+ worth of equipment which I can use for test and maintaining the quality of each and every amp that I build. I will be building each one by hand and testing them thoroughly.

http://www.mayflowerelectronics.com/products.html

Sounds awfully like a one man operation, and you would be "borrowing" the use of their equipment based on what you have said. You might should also consult your institution's equipment use policies. Typically, they tend to exclude using college resources to support one's private enterprises, but of course your institution could be different.

So you might want to update your website so that no one assumes the wrong thing :rolleyes:

 

[mikeaj]

It's a very minor and unimportant point, but I don't know why anybody would think that any of the builders are getting kits from JDSLabs or somewhere else.  It'd be cheaper to get the parts from one of the usual sources like Mouser, Digikey, etc.  It's about the same price if buying single-unit quantities, so of course if buying many more than that, you wouldn't be buying kits from somebody else.
 
I don't really see why the size of the operation is worth noting, either.  Regardless of who's stuffing boards, it's just one guy that designed the thing.  Support can be gotten here or any number of places.  Who cares?
 
 
That said, getting the boards from a 3rd party indicates that a builder's not making thousands of amps (or judges that the time, upfront investment, etc. are not worth it).  If you got a thousand boards made or so, it could be cheaper than buying them $6 each from JDSLabs.  To a smaller operation, a couple dollars saved per board is maybe not a huge deal when selling amps for $100+.
 
Now, some of the faceplate options with others' branding on them really do look amateurish.  Actually, the writing style and grammar on the website don't exactly help either.
 
 
Given the prices, I think more people should be buying from Mayflower.  It's just that JDSLabs already has name recognition and has a first-mover advantage.  They've got to be making around $100 per O2 sold (cost over materials, so not taking into account some maybe ~30 min build time, operational costs, etc.).  In any case, they seem to have secured enough funds to buy Voldemort's personal weapon of choice, a high-end dScope III audio analyzer (pricing something like $10k), according to the JDSLabs blog.  Good for them.

 

[cel4145]

Now, some of the faceplate options with others' branding on them really do look amateurish.  Actually, the writing style and grammar on the website don't exactly help either.

Given the prices, I think more people should be buying from Mayflower.  It's just that JDSLabs already has name recognition and has a first-mover advantage.  They've got to be making around $100 per O2 sold (cost over materials, so not taking into account some maybe ~30 min build time, operational costs, etc.).  In any case, they seem to have secured enough funds to buy Voldemort's personal weapon of choice, a high-end dScope III audio analyzer (pricing something like $10k), according to the JDSLabs blog.  Good for them.

I will say that I did contact both Mayflower and JDS Labs with questions before buying the ODAC and O2. I was very impressed with the professionalism of JDS Labs' response and how informative it was, and I went with their products.

I got the JDS Labs ODAC first through Sonic Electronix because JDS Labs was out of stock on their website. When I ordered the O2 directly from JDS Labs, mine didn't work right. I was very happy with how JDS Labs handled the situation. My O2 would only function properly on 9 volt Alkaline batteries. So JDS Labs immediately sent me a new power supply. When that didn't work, they immediately sent me a new O2, with prepaid return shipping label for RMA, no cost to me. And they didn't even charge for the 2nd O2 for crossshipping, as many places will do. Email support was fast (a few hours even at night) and extremely good. They bent over backwards, and I didn't have to ask them for anything. They just did it.

Some of the best service I've ever had for an online vendor.

 

[lorriman]

It's a very minor and unimportant point, but I don't know why anybody would think that any of the builders are getting kits from JDSLabs or somewhere else.  It'd be cheaper to get the parts from one of the usual sources like Mouser, Digikey, etc.  It's about the same price if buying single-unit quantities, so of course if buying many more than that, you wouldn't be buying kits from somebody else.

I don't really see why the size of the operation is worth noting, either.  Regardless of who's stuffing boards, it's just one guy that designed the thing.  Support can be gotten here or any number of places.  Who cares?

The posting was in reference to an unrelated issue. It wasn't making a big deal of a small operation or where the parts came from; as far as I could see the poster was merely speculating.

 

[TheDuke990]

Today I got my O2 + ODAC combo and with the low gain setting I'm very impressed but not with the high gain setting.
The music sounds a litte bit scratchy and distorted while using the high gain settings compared to the low gain setting by listening to the same volume level.
 
Low gain and maximum level (potentiometer at max level) -> no distortion
High gain and half level (potentiometer at half level) -> little bit of distortion
 
Do you picked up the same experiences by comparing the low and high gain settings ?
 
Headphone was my Beyer 880 (600 Ohm) and the O2 was driven by a power supply.

 

[RustA]

Quote:

Today I got my O2 + ODAC combo and with the low gain setting I'm very impressed but not with the high gain setting.
The music sounds a litte bit scratchy and distorted while using the high gain settings compared to the low gain setting by listening to the same volume level.
 
Low gain and maximum level (potentiometer at max level) -> no distortion
High gain and half level (potentiometer at half level) -> little bit of distortion
 
Do you picked up the same experiences by comparing the low and high gain settings ?
 
Headphone was my Beyer 880 (600 Ohm) and the O2 was driven by a power supply.

 
Yes. With two different combos, definitely... The lower, the better. IMHO