[JacobLee89]

Yeah, I've emailed them about this. They could make it a bit clearer I think. It makes sense an output bypassing the amp section (with power off) but I can't work out why anyone would need an RCA analogue input.

Thanks for the advice.

 
It would be more convenient with a 3.5mm analogue input. However there's a good collection of amps which do use RCA analogue input, such as the BH Crack. The perceived benefit could be that each (left/right) signal has their own ground.
 
Though for an ODAC there is little to gain sonically from choosing between the RCA and the 3.5mm version.

 

[anthk]

All of our O2+ODACs are wired so that the right 3.5mm jack serves as analog input to the O2, as well as DAC line-output.
 
So, you may use this jack to access the ODAC's line output. There's no need to turn the O2 off. The line output will function while O2 is powered on or off.
 
Let me know if you have any other questions.
 
Best regards,

  John Seaber
JDS Labs, Inc. | Tel: (314) 252-0936

This is the email response I got from JDS. I assume this is the same for mayflower, epiphany etc

 

[Solrighal]

All of our O2+ODACs are wired so that the right 3.5mm jack serves as analog input to the O2, as well as DAC line-output.
 
So, you may use this jack to access the ODAC's line output. There's no need to turn the O2 off. The line output will function while O2 is powered on or off.
 
Let me know if you have any other questions.
 
Best regards,

 



John Seaber
JDS Labs, Inc. | Tel: (314) 252-0936


This is the email response I got from JDS. I assume this is the same for mayflower, epiphany etc

Hopefully John will read this...

Dear John,

Many thanks for answering my email earlier today re. the rear RCA's on your limited edition model.

I'm no expert when it comes to anything really but might it not be a good idea to elaborate on these details on your website? It seems as though you rely too heavily on the site visitor having prior inside-knowledge of the products you sell. That seems like a somewhat flawed business plan, if you don't mind me saying. I like to think I am reasonably savvy when it comes to consumer electronics but I've been pretty much in the dark for the best part of 48hrs as to what your products are actually capable of. My money could easily have gone elsewhere in that time. That may well happen anyway but you can thank the UK government's ludicrous import tariffs for that.

Please don't take offence at my comments. Your products are great. Your personal service is clearly excellent. I just feel your website, though attractive, could be more informative.

A fan.

 

[r010159]

Hopefully John will read this...

Dear John,

Many thanks for answering my email earlier today re. the rear RCA's on your limited edition model.

I'm no expert when it comes to anything really but might it not be a good idea to elaborate on these details on your website? It seems as though you rely too heavily on the site visitor having prior inside-knowledge of the products you sell. That seems like a somewhat flawed business plan, if you don't mind me saying. 

[some of post deleted]

Please don't take offence at my comments. Your products are great. Your personal service is clearly excellent. I just feel your website, though attractive, could be more informative.

A fan.

 
I think John is relying on the information already available for the O2 + ODAC, for instance, from the designer himself in his blogs. But I agree that the technical discussion of NwAvGuy should also be, at the very least, linked to by his site.
 
BG

 

[Solrighal]

I think John is relying on the information already available for the O2 + ODAC, for instance, from the designer himself in his blogs. But I agree that the technical discussion of NwAvGuy should also be, at the very least, linked to by his site.

BG

You're probably right but it wouldn't take much to fill in the gaps. I'm only mentioning because I do like to support the smaller companies. I'm gonna take a punt and suggest we're unlikely to see Mr Sony or Mr Panasonic posting on these forums, but John does. That attention makes such a difference for the end-user. I kinda wish I hadn't said anything now.

 

[hekeli]

I kind of agree with the vague descriptions.
 
Even Walter who I love could be a smidgen more descriptive. For example O2 desktops RCA output - is it volume controllable (preamp) is common question - yes it is!
 
(And these have nothing to do with NwAvGuy, all the mods and tweaks are done by the seller!)
 
Also the gain stuff should be clearly explained since it's a common source of gripe (why am I hearing distortion??). 1x / 3x should be suggested default when bundling with ODAC.

 

[Solrighal]

I kind of agree with the vague descriptions.

Even Walter who I love could be a smidgen more descriptive. For example O2 desktops RCA output - is it volume controllable (preamp) is common question - yes it is!

(And these have nothing to do with NwAvGuy, all the mods and tweaks are done by the seller!)

Also the gain stuff should be clearly explained since it's a common source of gripe (why am I hearing distortion??). 1x / 3x should be suggested default when bundling with ODAC.

This is true. My frustration is amplified (geddit?) by the fact that my internet speed where I live is ridiculous which means that, particularly the JDS Labs site which does look beautiful, takes an eternity to load. This is nobody's fault but my stupid country. The UK is a joke. Still, even that's changing as Scotland is about to vote for independence. Then the world is our oyster. The future is bright.

 

[r010159]

You're probably right but it wouldn't take much to fill in the gaps. I'm only mentioning because I do like to support the smaller companies. I'm gonna take a punt and suggest we're unlikely to see Mr Sony or Mr Panasonic posting on these forums, but John does. That attention makes such a difference for the end-user. I kinda wish I hadn't said anything now.

 
I hope I did not come across aggressive. I think you mentioning this will actually help John gauge what he can do on his end to make a difference in future purchases.

 

[Solrighal]

I hope I did not come across aggressive. I think you mentioning this will actually help John gauge what he can do on his end to make a difference in future purchases.

Not at all my friend, no problem. It's intended to be constructive criticism but sometimes I get taken the wrong way or I'm maybe not quite as polite as some think I should be. If I genuinely didn't care about these smaller companies (not small but not Sony either) I wouldn't have said anything at all. Web design kinda is my field, though only as a hobby. One that's not got a lot of attention of late since I keep buying damned expensive gadgets

 

[MrMateoHead]

  I kind of agree with the vague descriptions.
 
Even Walter who I love could be a smidgen more descriptive. For example O2 desktops RCA output - is it volume controllable (preamp) is common question - yes it is!
 
(And these have nothing to do with NwAvGuy, all the mods and tweaks are done by the seller!)
 
Also the gain stuff should be clearly explained since it's a common source of gripe (why am I hearing distortion??). 1x / 3x should be suggested default when bundling with ODAC.

I know JDS would be willing to provide you with either 1X / 2.5X or 2.5X / 6.5X if you requested it - the old website used to tell you you could choose.
 
But, by default, the 2.5X / 6.5X gain levels are ideal for matching the O2 to a 2V source (2.5X reaches full power), or a typical 1V source (6.5X is perfect for Mp3 player, tablet, computer, etc.). 6.5X also comes in handy for HDR recordings as sometimes I struggle at 2.5X to reach the volume I want. I've also, btw, never been able to clip the O2 - I've only ever heard my recordings clip.
 
Then again, the O2 is very powerful, so many persons using very efficient cans with it should, IMHO, use the windows or whatever source volume control to reduce signal strength so they can twist the knob as much as they want to. That is a lot better than eliminating rid of useful gain headroom - especially when the O2 is black no matter the gain/volume level.

 

[Solrighal]

Then again, the O2 is very powerful, so many persons using very efficient cans with it should, IMHO, use the windows or whatever source volume control to reduce signal strength so they can twist the knob as much as they want to. That is a lot better than eliminating rid of useful gain headroom - especially when the O2 is black no matter the gain/volume level.

You raise a point I've always been confused about. Does it really make no difference to sound quality what level is sent out to the DAC? I realise the volume level would be reduced but would the quality not be reduced too?

 

[headwhacker]

I know JDS would be willing to provide you with either 1X / 2.5X or 2.5X / 6.5X if you requested it - the old website used to tell you you could choose.

But, by default, the 2.5X / 6.5X gain levels are ideal for matching the O2 to a 2V source (2.5X reaches full power), or a typical 1V source (6.5X is perfect for Mp3 player, tablet, computer, etc.). 6.5X also comes in handy for HDR recordings as sometimes I struggle at 2.5X to reach the volume I want. I've also, btw, never been able to clip the O2 - I've only ever heard my recordings clip.

Then again, the O2 is very powerful, so many persons using very efficient cans with it should, IMHO, use the windows or whatever source volume control to reduce signal strength so they can twist the knob as much as they want to. That is a lot better than eliminating rid of useful gain headroom - especially when the O2 is black no matter the gain/volume level.

If you use the O2 with sensitive iems, then the default 2.5x / 6.5x is way too much regardles whether your source is a 1V mp3 player or the 2V ODAC.

Fortunately, this is easy to address. Just clip the resistor on the 6.5x bridge and you instantly have a 1x /2.5x gain option.

You can reduce the gain further to 0.5x or 0.25x for those uber sensitive iems. Just need to find the right resistor value.

 

[SilverEars]

You can reduce the gain further to 0.5x or 0.25x for those uber sensitive iems. Just need to find the right resistor value.

How is that possible?  The gain equation is 1+R1/R2 or something like that.  if you clip R2 for example, it's infinate resistance.  Which means gain=1.  Therefore, it can never be lower than one I would think.
 
Taken from the designer's website regarding gain:
 
RESISTOR VALUES: Some amplifiers let you set the gain by changing resistor values. The diagram to the right shows a typical non-inverting amplifier stage. The gain is given by 1 + 1000/500 = 3. For all the math, see Wikipedia Gain andWikipedia Amplifiers. Some amplifiers may have multiple gain stages, in which case you have to multiply the gain of each stage together. So an amp with a 2X and 3X stage has a total gain of 6X.
 

 

[headwhacker]

How is that possible?  The gain equation is 1+R1/R2 or something like that.  if you clip R2 for example, it's infinate resistance.  Which means gain=1.  Therefore, it can never be lower than one I would think.
 
Taken from the designer's website regarding gain:
 
RESISTOR VALUES: Some amplifiers let you set the gain by changing resistor values. The diagram to the right shows a typical non-inverting amplifier stage. The gain is given by 1 + 1000/500 = 3. For all the math, see Wikipedia Gain andWikipedia Amplifiers. Some amplifiers may have multiple gain stages, in which case you have to multiply the gain of each stage together. So an amp with a 2X and 3X stage has a total gain of 6X.
 

 


Ah, you are right, 1x is the smallest gain possible. I completely mixed it up with the UHA-6S which can be modified up to -12dB (0.25x)

 

[hekeli]

But, by default, the 2.5X / 6.5X gain levels are ideal for matching the O2 to a 2V source (2.5X reaches full power), or a typical 1V source (6.5X is perfect for Mp3 player, tablet, computer, etc.). 6.5X also comes in handy for HDR recordings as sometimes I struggle at 2.5X to reach the volume I want. I've also, btw, never been able to clip the O2 - I've only ever heard my recordings clip.

 
While I have a very hard time understanding why anyone would care to use O2 with some tablet etc, even ignoring that, why isn't all of this info on the sellers pages so everyone understands what they are getting into.. but yeah sure you can always clip a resistor..
 
Anyways, I've rarely need more than unity gain with any of my headphones. Atleast it's better quality in theory, isn't that why we use O2 anyway..