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O2 AMP + ODAC - Page 272

post #4066 of 4074
Quote:
Originally Posted by jseaber View Post

45 mW --> 100 dB
141 mW --> 105 dB
447 mW --> 110 dB
794 mW --> 112.5 dB
1413 mW --> 115 dB

P = [(VRMS)^2 / Z]
VRMS = (P*Z)^0.5
Where: Z = headphone impedance in ohms, P = output power in mW


See also:
https://docs.google.com/a/jdslabs.com/spreadsheets/d/1****TwWffXKld7PgHt5wZOP7KnBVO6SyvG9yZEJ-smI/edit#gid=1006269980
So 7Vrms clipping point would come up to how many dB?
post #4067 of 4074
Quote:
Originally Posted by diamondears View Post


So 7Vrms clipping point would come up to how many dB?

 

O2 will start to clip around 6.8 Vrms. Theoretically O2 can only drive HE-6 at 113dB max.

post #4068 of 4074
Quote:
Originally Posted by diamondears View Post


So 7Vrms clipping point would come up to how many dB?

 

Clipping should occur close to 110dB listening volume. It's easy to refer to an SPL chart

 

Slightly off topic: Peak output from O2 is 7.55VRMS for 150+ ohm loads. I need to verify how NwAvGuy arrived at the 7.0VRMS limit. It may be a conservative rounding error. Or a real input limit. Poke me if this isn't answered this week!

 

Edit: Sorry for the repeat posts, headwacker. I'll sign off.


Edited by jseaber - 2/22/15 at 7:16pm
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post #4069 of 4074
Quote:
Originally Posted by headwhacker View Post

O2 will start to clip around 6.8 Vrms. Theoretically O2 can only drive HE-6 at 113dB max.

113dB is very loud sir! 113dB isn't enough on your classical music you mentioned?
Quote:
Originally Posted by jseaber View Post

Clipping should occur close to 110dB listening volume. It's easy to refer to an SPL chart

Peak output from O2 is 7.55VRMS. I need to verify how NwAvGuy arrived at the 7.0VRMS limit. It may be a conservative rounding error. Or a real input limit. Poke me if this isn't answered this week!

Edit: Sorry for the repeat posts, headwacker. I'll sign off.

110dB is good enough for me! And that's the extreme hungry power HE-6. Don't understand the talk about O2 lacking power.
post #4070 of 4074
Quote:
Originally Posted by jseaber View Post
 

 

Clipping should occur close to 110dB listening volume. It's easy to refer to an SPL chart

 

Peak output from O2 is 7.55VRMS. I need to verify how NwAvGuy arrived at the 7.0VRMS limit. It may be a conservative rounding error. Or a real input limit. Poke me if this isn't answered this week!

 

Edit: Sorry for the repeat posts, headwacker. I'll sign off.

 

No harm done John. Your post is just as important and informative. I think Nwayguy just use 7Vrms as a conservative limit but O2's measured peak is well beyond 7Vrms. I think it's 7.3Vrms if you extrapolate it from his published measurements at 150 and 600 Ohm load. 

post #4071 of 4074
Quote:
Originally Posted by diamondears View Post


113dB is very loud sir! 113dB isn't enough on your classical music you mentioned?
110dB is good enough for me! And that's the extreme hungry power HE-6. Don't understand the talk about O2 lacking power.

 

113dB is an ideal level. Usually you have 1 to 3dB margin of error. So John's estimate of 110dB represents real world usage scenario. That is why I always add 3dB on top of my target SPL when looking for an amp.

 

Try it first so you can see why. Classical music has lots of peaks and and silent passages. And the difference between the silent and the loudest level is around 20dB to 30 dB. Modern pop/rock songs (highly compressed) would work and enough for HE-6 driven by O2.  

post #4072 of 4074
Quote:
Originally Posted by headwhacker View Post

Not the widest DR but try the album Tchaikovsky: The Nutcracker. I think it is the 2011 remaster.

Thanks

What record label?
post #4073 of 4074
Quote:
Originally Posted by rudi0504 View Post

dcb2a9fa.jpg



d9f8299d.jpg


JDS Lab ODAC usb DAC + JDS Lab O 2 head amp full modification with Black Gate Capasitors
I has to know where that awesome case comes from! Or has you made it yourself? *k back to normal english*
post #4074 of 4074
Quote:
Originally Posted by jseaber View Post

 

Clipping should occur close to 110dB listening volume. It's easy to refer to an SPL chart

 

Slightly off topic: Peak output from O2 is 7.55VRMS for 150+ ohm loads. I need to verify how NwAvGuy arrived at the 7.0VRMS limit. It may be a conservative rounding error. Or a real input limit. Poke me if this isn't answered this week!

 

Edit: Sorry for the repeat posts, headwacker. I'll sign off.

 


7.55V RMS at clip, or with THD under 0.1%?
With 12V Rail, and tossing about 0.35V on the schottky diode (D1/D5), leaves 11.65V to the OP-amp.
7.55V RMS is 10.68V peak, which leave less than 1V to be shared between the Vce of the VAS BJT, and the Vbe of the driver.
Given the Vbe of the driver around/at-least 0.65V, leaves less than 0.35V for the Vce of the VAS BJTs, and BJTs really do not like to work in that area, in the analog space.
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