[ClieOS]

Quote:

Oh alright it was only as on jds labs site on specs it said impedance = impedance of op-amp! Ok thanks for you help and I think it's all sorted now
 

 
The biggest contributor to output impedance is usually resistors (and sometime caps) between the opamp and the output jack. What JDS meant to say it that there is no resistors (or anything contribute to resistance) between the opamp and the output jack so all the impedance comes from the opamp internal impedance, which is usually very small and under 1 ohm.

 

[Swimsonny]

Not sure how the SQ goes from the CMOYs treble to the O2's 'laid-back mids' - you lost me there. 

Oops yes I have made a mistake their which is now corrected, I meant to to say laid back highs and accidnently put mids. Thanks for pointing that out.

 

[Swimsonny]

Trust me, you'll get there. A year ago, when I purchased my ATH-M50, I'd have never expected to have and hoard so much equipment by now. My list on Head-Fi is not even 3/4 of what I have.

However muh id love to I'm a jobless 16 year old so it's hard to be making money to afford is hard but yeh my collections is growing pretty rapidly!

 

[mikeaj]

Quote:

The biggest contributor to output impedance is usually resistors (and sometime caps) between the opamp and the output jack. What JDS meant to say it that there is no resistors (or anything contribute to resistance) between the opamp and the output jack so all the impedance comes from the opamp internal impedance, which is usually very small and under 1 ohm.

Small correction:  but actually there are resistors.  The output is two 4556 in parallel for each channel, each with a 1 ohm resistor in between the op amp output and the headphone jack, with no DC blocking cap.  So the output impedance is around 0.5 ohms, which is the important part.  It's not a factor.
 
 
 
By the way, OP mentions the gain being 3 dB, which would be very small.  EHP-O2 comes default with 1x low gain and 2.5x high gain, which is quite arguably not enough using a portable source and insensitive and high impedance headphones.  20 log(2.5) = 8 dB.

 

[ClieOS]

Quote:

Small correction:  but actually there are resistors.  The output is two 4556 in parallel for each channel, each with a 1 ohm resistor in between the op amp output and the headphone jack, with no DC blocking cap.  So the output impedance is around 0.5 ohms, which is the important part.  It's not a factor.
 

 
We are talking about the JDS (cmoyBB), not the (Epiphany Acoustics') O2.
 
 

 

[Swimsonny]

By the way, OP mentions the gain being 3 dB, which would be very small.  EHP-O2 comes default with 1x low gain and 2.5x high gain, which is quite arguably not enough using a portable source and insensitive and high impedance headphones.  20 log(2.5) = 8 dB.

When I said 3db I was referring to how much is added when the gain switch is on not the base gain of the amplifier.

 

[DeathDomokun]

Have you noticed any significant differences between an AC transformer and 9V batteries?

 

[Swimsonny]

Have you noticed any significant differences between an AC transformer and 9V batteries?

I guess your talking about the cmoy which my version is not rechargeable so I only use 9v batteries! So I can't say! Anything thing else you'd like to know?

 

[DeathDomokun]

I was actually talking about the O2. I've already ordered one and I was wondering whether it's worth shelling out $30 on the AC adaptor or just using 9V batteries. My T50RP's came today and I've already started modding them

 

[Swimsonny]

Oh I think it will be cheaper in the long run getting an ac adapter! Also if your using it desktop you can leave it constantly plugged in! I have read about the t50s but dunno if if have time to do all the mods....

 

[DeathDomokun]

Well I received them this afternoon, already I've mass loaded plasticine around the driver and applied sound deadener to the cups. It's not as time consuming as you'd think, idk if LFF is still selling/making Paradox's, but they're supposed to be very good.

 

[jseaber]

Quote:

I was actually talking about the O2. I've already ordered one and I was wondering whether it's worth shelling out $30 on the AC adaptor or just using 9V batteries. My T50RP's came today and I've already started modding them

The O2's batteries aren't easily replaceable, not to mention they get something like 8 hours run time. At $6 USD/pack, you'd pay $0.75/hour of listening! And you'd need to carry around a screwdriver to change them. Finally, the enclosure holes aren't threaded and will therefore strip if screws are repeatedly removed.
 
I think you'll agree that an AC adapter is mandatory. O2 is not a portable amp. ClieOS posted a great picture in another thread showing just how large O2 really is.

 

[shadow419]

Quote:

The O2's batteries aren't easily replaceable, not to mention they get something like 8 hours run time. At $6 USD/pack, you'd pay $0.75/hour of listening! And you'd need to carry around a screwdriver to change them. Finally, the enclosure holes aren't threaded and will therefore strip if screws are repeatedly removed.
 
I think you'll agree that an AC adapter is mandatory. O2 is not a portable amp. ClieOS posted a great picture in another thread showing just how large O2 really is.

It's not tiny by any sense of the word, but it is portable imo.  If I can use a piece of electronic equipment at the park or on a commute, it is portable.  I'd still get the AC adapter since it's way cheaper to just recharge batteries as needed vs. replacing them.

 

[Swimsonny]

The O2's batteries aren't easily replaceable, not to mention they get something like 8 hours run time. At $6 USD/pack, you'd pay $0.75/hour of listening! And you'd need to carry around a screwdriver to change them. Finally, the enclosure holes aren't threaded and will therefore strip if screws are repeatedly removed.
 
I think you'll agree that an AC adapter is mandatory. O2 is not a portable amp. ClieOS posted a great picture in another thread showing just how large O2 really is.

Yeh he is right and I would not want to play around changing batteries so I think the ac adapter is a good buy!

And so everyone can get an idea for size I will upload a picture comparing cMoy to the O2 and an iPhone 4 as well do you get an understanding for size!

 

[Swimsonny]

 
Just a rough guide of size!