[raoultrifan]

   
Sounds cool, time for some measurement comparisons.

I'll copy-paste from my above post, hope you don't mind:
"I was only using my PicoScope to check for any possible oscillations and to measure voltage output for several audio signals taken from audiocheck.net (at least 10 wave forms at around -3dB each, between 20-20.000Hz, dummy load resistive & capacitive was used). Output signal is completely flat and no strange FFT harmonics could be seen no matter of the op-amp used (well, with some op-amps I could see an increase in THD but only when output voltage gets close to 7V RMS, but that's another story)."

  Can someone explain the difference between "general use" and "audio use?"

Well, we're already on topic, but a lot of op-amps are designed for audio, video and telecommunications purpose. Some manufacturers are re-branding some of these op-amps as being "for audio use" after several tests (stability, audio quality etc.). I personally like the OPA SoundPlus series, but I found better replacement form them in some configurations (MUSES01 in I/V stage and BURSON V5 or MUSES02 in LPF and VAS stages).
 
Everyone has ears to A/B test them all.

 

[upstateguy]

 

Quote:

<snip>  
So, replacing this one with a real solid-state device like V5-dual from BURSON might be a real upgrade for some of us, especially for mod-ers and DIY-ers.

 
Sounds cool, time for some measurement comparisons.

I'll copy-paste from my above post, hope you don't mind:
"I was only using my PicoScope to check for any possible oscillations and to measure voltage output for several audio signals taken from audiocheck.net (at least 10 wave forms at around -3dB each, between 20-20.000Hz, dummy load resistive & capacitive was used). Output signal is completely flat and no strange FFT harmonics could be seen no matter of the op-amp used (well, with some op-amps I could see an increase in THD but only when output voltage gets close to 7V RMS, but that's another story)."

 
So now I'm not sure what you're saying. 
 
Did you say you didn't notice any measurement differences regardless which op-amp was used?
 
If measurement differences, which relate to audibility, are not there, why could this be called an upgrade?  <just asking>

 

[raoultrifan]

Hi upstateguy, 
 
I couldn't see any differences on my tests, exactly. Perhaps RMAA or ARTA tests may reveal some small improvements in IMD, THD and noise, but I don't have access to a sound-card having a decent analog input, sorry.
 
What I was trying to say in my previous posts is that some op-amps just sound better than others without measuring better (check datasheet of MUSES02 and compare it with LME49720's datasheet for example). A better channel separation inside the op-amp will increase sound-stage and depth, FET-input op-amps may sound better than BJT-input op-amps (read about odd-order harmonics on OPA604 datasheet) etc.
 
To my ears BURSON SS V5-dual when used in voltage amplification stage (first op-amp) sounds definitely better in my Objective2 headamp than other op-amps tested (NJM2608, LME49720, MUSES8820 etc.). Usually solid-state devices sound better than op-amp devices.
 
Regards, 
Raul.

 

[Blarzor]

Hey guys, can you help me what gain settings to get on my O2 that I'm ordering in near future? I'm buying O2 only, without ODAC. I will be using my interface Focusrite Scarlett 2i4 which has 1.46 volts output on its DAC.
 
So basically, I'm getting ATH-R70X headphones, which according to reviews require optimal 5V or 7V for pop/classical. Does that mean that my recommended minimum gain should be 3,4x on O2 (5V : 1,46V = 3,4x?). Is this how you calculate it?
 
Can you guys suggest me the gain settings before I buy O2?

 

[raoultrifan]

I would go with 1-1.5X as lowest gain and 3-3.5X as highest gain, if you have this setup available for buying. Now, this really depends on your headset used.

 

[Ver7o]

Hello good ppl.
 
I'm thinking of getting O2+ODAC combo for my setup and for any future setups. So my current setup are powered studio monitors and HD598 cans. So my thinking here is that with this combo I can make my setup futureproof if I ever decide on harder to drive cans or passive speakers.
 
Now my questions are;
- how would 1x gain work with powered speakers?
- does 1x actually mean there is no amplification of the output signal (pre-amp option)?
- has anyone tried powering passive speakers with this combo (on 3.3x gain?)
 
Thank you for any kind of answers.

 

[Blarzor]

@raoultrifan My headphone use will be for mixing first and enjoyable listening second (gothic rock, progressive rock, classic rock)

 

[raoultrifan]

  Now my questions are;
- how would 1x gain work with powered speakers?
- does 1x actually mean there is no amplification of the output signal (pre-amp option)?
- has anyone tried powering passive speakers with this combo (on 3.3x gain?)
 
Thank you for any kind of answers.

I'm not sure I understand your questions, sorry. Shouldn't you use ODAC to power the amped-speakers?
 
There's also an ODAC/O2 combo that has RCA out so I believe that might suit better for you: http://www.headnhifi.com/amplifiers/OBJ_O2_ODAC_digital2 (I don't know how Walter did connected both O2 input and RCA outputs, but feel free to ask him; I had my ODAC modded with a small switch to switch between O2 input and RCA outputs).
 

@raoultrifan My headphone use will be for mixing first and enjoyable listening second (gothic rock, progressive rock, classic rock)

 
I believe 1-1.5X for lowest gain setting and 3-3.5X for the highest setting should suffice, but that depends on the headphones you'd like to use. In your case to get the max. power available out of your O2 means to use the gain of 5X that translates in about 7.3V RMS for your Scarlett DAC (though, something around 4.8-4.9X would be recommended to prevent clipping).
 
You need to calculate yourself the RMS voltage needed for your headphones and carefully choose desired gains. Headphones manufacturer's specs or Innerfidelity and something like http://www.digizoid.com/headphones-power.html might help you out.

 

[Blarzor]

 
I believe 1-1.5X for lowest gain setting and 3-3.5X for the highest setting should suffice, but that depends on the headphones you'd like to use. In your case to get the max. power available out of your O2 means to use the gain of 5X that translates in about 7.3V RMS for your Scarlett DAC (though, something around 4.8-4.9X would be recommended to prevent clipping).
 
You need to calculate yourself the RMS voltage needed for your headphones and carefully choose desired gains. Headphones manufacturer's specs or Innerfidelity and something like http://www.digizoid.com/headphones-power.html might help you out.

 
I'm buying Audio Technica R70x which has impedance of 470 ohms and 99 dB sensitivity, I don't know if that is 99db SPL/mW or SPL/V though :/
 
http://www.audio-technica.com/cms/headphones/f39784ce643a82e6/index.html

 

[raoultrifan]

Blarzor, you should probably aim for the 4.8-5X for the max. gain. The lowest gain feel free to choose it between 1.5-2.5X, depending on your thoughts (future headphones perhaps?).
 
Note: Read the "Loudness" chapter from here: http://www.head-fi.org/t/765004/audio-technica-ath-r70x-in-depth-review-impressions#post_11565945, it's an interesting review that also proves that R70x could be driven with a headamp able to deliver between 5-7V RMS (though the reviewer claims that even an iBasso DX90 that has a maximum output voltage of 2.69 Vrms could do the job with R70x).

 

[Blarzor]

  Blarzor, you should probably aim for the 4.8-5X for the max. gain. The lowest gain feel free to choose it between 1.5-2.5X, depending on your thoughts (future headphones perhaps?).
 
Note: Read the "Loudness" chapter from here: http://www.head-fi.org/t/765004/audio-technica-ath-r70x-in-depth-review-impressions#post_11565945, it's an interesting review that also proves that R70x could be driven with a headamp able to deliver between 5-7V RMS (though the reviewer claims that even an iBasso DX90 that has a maximum output voltage of 2.69 Vrms could do the job with R70x).

 
Thanks for all the help. I learned to do the calculations overnight with the help of NwAvGuy's blog, I calculated the amount of gain I need, but the only thing I still don't understand is the concept of excess gain.
 
I used these tools:
http://www.digizoid.com/headphones-power.html
http://www.sengpielaudio.com/calculator-gainloss.htm
 
My calculations for R70x are the following:
 
To reach 110dB with my DAC (or Source as called in the article which outputs 1.46V), I need gain of 1,66x. To reach 100dB with my DAC, I need gain of 0,52x. To reach 115dB with my DAC I need gain of 2,96x.
Now, I don't really understand the excess gain, if I add 3db (excess gain) to the 2,96x (which translates into 9.43dB) I get 12.43dB which translates to 4.18x.
 
I mean, I got all the calculations going on, I just don't know what's the difference between looking at 115dB minimum gain calculation with added excess gain.
 
Also, does having let's say 1.5x minimum gain value translate into reaching maximum 110db when my volume button is all the way to the end up? Is this how it works?

 

[Fingerling]

Hi,
 
I didn't find the answer to my question by searching the thread.
 
I have a O2+ODAC with RCA output: is it capable of driving my Eltax Monitor III?
 
Thanks

 

[WilliamLeonhart]

  Hi,
 
I didn't find the answer to my question by searching the thread.
 
I have a O2+ODAC with RCA output: is it capable of driving my Eltax Monitor III?
 
Thanks

No they're for headphones. But you can try using the O2 as pre-amp.

 

[Fingerling]

  No they're for headphones. But you can try using the O2 as pre-amp.

OK but why? What happens if I try (I ask before because I don't want to move my Eltax for nothing)?
 
So the RCA output are for active speakers only? Or as a tiny pre-amp (but what is the point?)?

 

[castleofargh]

 

  No they're for headphones. But you can try using the O2 as pre-amp.

OK but why? What happens if I try (I ask before because I don't want to move my Eltax for nothing)?
 
So the RCA output are for active speakers only? Or as a tiny pre-amp (but what is the point?)?

headphones will typically be in the 16 to 600ohm area, and those in the 16ohm area will most likely be IEMs with very high sensitivity needing very very little power. 5mW will get most IEMs pretty loud.
while speakers are at least in theory dancing in the 4 to 8ohm area, while needing a lot of power. usually a few W.
different amps for different needs.