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Can the O2 amp fully drive the Beyerdynamic T1?

post #1 of 32
Thread Starter 

My question is: can the O2 amp fully drive the Beyerdynamic T1 at typical listening volumes (i.e. without clipping etc.)? Here are some resources I've looked at to try and figure this out:

 

Resources:

 

- Measurements of Beyerdynamic T1 (impedance seems to reach a peak of 1400 ohms!):

 

  http://www.innerfidelity.com/images/BeyerdynamicT1.pdf

 

- Specs of O2 JDSLabs (outputs 88 mW into 600 ohm load) [note that I'm looking at the epiphany acoustics version which has a maximum gain of 5x as opposed to 6.5x for the JDSlabs model]:

 

  http://www.jdslabs.com/products/35/objective2-headphone-amplifier/

 

- Power requirements (at nominal impedance i.e. 600 ohm) calculated to reach 120 dB 

  (T1: 63 mW, 10 mA, 6.15 V rms):

 

  http://www.head-fi.org/t/476345/headphone-sensitivity-power-requirements-compared

 

- Power requirement (taking impedance at 500 Hz i.e. 750 ohm) calculated to reach 110 dB SPL

  (T1: 16.786 mW, 4.731 mA, 3.548 V):

 

http://www.head-fi.org/t/668238/headphones-sensitivity-impedance-required-v-i-p-amplifier-gain 

 

Conclusion?

 

From the above data what I understand is that the epiphany acoustics O2 amp can supply a maximum of around 10 V into a 600 ohm load with a power of 88 mW. Also from the data supplied for the O2 amp, it appears that at larger impedances less power is supplied i.e. 613 mW into a 33 ohm load and 355 mW into a 150 ohm load. Therefore for impedances above 600 ohms the power supplied is expected to be less than 88 mW.

 

Therefore there is just enough power and voltage to drive the T1 to 120 dB at an impedance of 600 ohm but at certain frequencies with very high impedances (i.e. 1400 ohm) it will probably not supply enough power.

 

At 110 dB the O2 should easily be able to supply enough voltage and power at all frequencies. 

 

Am I reading all this data correctly? 


Edited by PTom - 2/24/14 at 3:42am
post #2 of 32
Quote:
Originally Posted by PTom View Post
 

Therefore there is just enough power and voltage to drive the T1 to 120 dB at an impedance of 600 ohm but at certain frequencies with very high impedances (i.e. 1400 ohm) it will probably not supply enough power.

That's 120 dB at a nominal impedance of 600 Ohms.

 

Even if you can 'only' power it to 110 dB, that's still ear-damaging loudness.

post #3 of 32
Thread Starter 

Thanks for the reply higbvuyb. When you're watching movies for example isn't it likely that the volume will be greater than 110 dB in certain scenes for a few seconds i.e. explosions, gun fire etc. so wouldn't these effects be suppressed when driving the T1 with an O2 amp?


Edited by PTom - 2/24/14 at 5:07am
post #4 of 32

There's a very big difference between the power requirements to generate a single sine wave (one sound frequency) at a certain loudness level without distortion and listening to music with lots of frequencies, dramatic shifts etc.

 

The usual power/loudness calculations are -by necessity and because a standard is needed- simplifications.  Essentially they represent a single, static snapshot.  The figures you arrive at through those -by necessity and this is valid for ALL manufacturers- calculations and the conclusions derived from them are akin to what you'd get reading a description of the Mona Lisa without picture vs seeing the actual work of art in the Louvre.

 

The OP's reasoning seems to me to be correct.  I found out that discussions regarding the O2 tend to generate lots of emotions here and rational argumentation is lost along the wayside.  Using more complex models and piling on the mathematics brings nothing, those who want to be convinced will be convinced, the others will just stay the course.  Been there, done that and frankly, I don't fancy another rant or deleting hate mail from my inbox.

 

So I'll keep my opinion short and sweet but just want to say that:

 

1) I own the Epiphany acoustics version of the O2 and for the price I believe it to represent very good value but it's a simple tool and like any tool you need to use it for what it is designed.

2) I never owned the T1 but did own the DT-880.  I know they're different.  I hooked the DT-880 (600 Ohm) up to my O2 clone and to various other and more expensive/powerful /built to different specs amplifiers.  My conclusion was that yes, at moderate listening levels the O2 will drive them but not to the best of what they were capable of.  Going by the specs I suspect it will be the same with the T1, performance will at best be marginal.  

3) Based on the above and given the cost of the T1 it would be silly not to try to exploit its capabilities to the fullest and for that the O2 is not the right amp imo.

4) All said and done, I believe what you should do is not accept my word for it but neither go blindly by what some fanboys -who typically own nickel and dime amplification equipment only but try to convince themselves that anything else would be excessive- proclaim.  Get the opinions of people who run/have run the T1 from an O2 but who also have other (high end) amplifiers.  They're imo the best references.

 

If it comes down to a financial decision in the sense that you have funds to purchase either the T1 but only enough left to drive it from the O2 or purchase a lesser headphone and better amplification then by all means, get the T1 and the O2, save up and upgrade later.

 

Good luck!

post #5 of 32
Quote:
Originally Posted by Xenophon View Post

2) I never owned the T1 but did own the DT-880.  I know they're different.  I hooked the DT-880 (600 Ohm) up to my O2 clone and to various other and more expensive/powerful /built to different specs amplifiers.  My conclusion was that yes, at moderate listening levels the O2 will drive them but not to the best of what they were capable of.  Going by the specs I suspect it will be the same with the T1, performance will at best be marginal.

Most of those who think the O2 is the Only2 probably haven't tried many other amps.

1. Were you using the "stock" AC/AC adapter or the more powerful one recommended for higher impedance (e.g., 12 VAC @ 1.0A)?

2. Do you think that your observations would apply to a 300 ohm model such as HD600? I just bought K340 400 ohms, and I hope to run it from the O2.
post #6 of 32
Quote:
Originally Posted by Claritas View Post


Most of those who think the O2 is the Only2 probably haven't tried many other amps.

1. Were you using the "stock" AC/AC adapter or the more powerful one recommended for higher impedance (e.g., 12 VAC @ 1.0A)?

2. Do you think that your observations would apply to a 300 ohm model such as HD600? I just bought K340 400 ohms, and I hope to run it from the O2.

I've used both the normal adaptor and a more powerful model.  My setup here is a bit particular regarding power in the sense that I'm sitting in an office in Delhi that's crammed to the nook with computer systems and power supply from the grid is not an option so everything runs redundantly from a generator-backed large UPS.  The loop going to my office (where the O2 is located) has separate electricity/power stabilisation and conditioning equipment installed that runs to tolerances that are far tighter than what the average household (in the US or Europe) has available.  Fortunately not paid out of my own pocket.

 

For the HD-600 I cannot say, what I can say is that I ran my HD-800 from the O2 for a couple of months here (it's currently in my other house in Europe) and yes, with those it applied.  They're also 300 Ohm nominally but extrapolation to the 600 is risky, I recommend you take a look at their characteristics.  Also, the 800 is notoriously difficult regarding amping and I didn't have my other amps here to do an A/B comparison.

post #7 of 32
Quote:
Originally Posted by Xenophon View Post

I've used both the normal adaptor and a more powerful model.  My setup here is a bit particular regarding power in the sense that I'm sitting in an office in Delhi that's crammed to the nook with computer systems and power supply from the grid is not an option so everything runs redundantly from a generator-backed large UPS.  The loop going to my office (where the O2 is located) has separate electricity/power stabilisation and conditioning equipment installed that runs to tolerances that are far tighter than what the average household (in the US or Europe) has available.  Fortunately not paid out of my own pocket.

For the HD-600 I cannot say, what I can say is that I ran my HD-800 from the O2 for a couple of months here (it's currently in my other house in Europe) and yes, with those it applied.  They're also 300 Ohm nominally but extrapolation to the 600 is risky, I recommend you take a look at their characteristics.  Also, the 800 is notoriously difficult regarding amping and I didn't have my other amps here to do an A/B comparison.

Thank you.

Did you notice many differences between the two adapters?

Is your O2 set to standard gain? Mine is set to the lowest gain (2.5/1.0x) because I listen at very low volumes. I wonder how that might affect the sound.
post #8 of 32

To be honest I didn't detect any audible difference between the adapters.  I listen to classical only, also at lowish volumes and use the lowest gain setting.  When I use higher gain there's a noticeable degradation in details such as reproduction of higher piano notes, xylophone, strings, cymbals...they lose detail.  Subjective appreciation of course but that's my impression.

post #9 of 32
Thanks. That's helpful, especially as we have common genre, gain seeting, and volume preferences.

(I catch up on your thread every few weeks, but I'm not into the big planars for classical; and they were properly amped when I tried them. I might buy a Violectric one day though, if I enjoy the sound. Good luck with the upcoming experiment.)
post #10 of 32
FWIW, I got the JDS Labs O2. It came with the default 2.5x/6.5x gain switch. I use the T1 and with sensitive iems and drive them with O2. So I have to clip one resistor so I get a 1x/2.5x gain.

at 2.5X gain T1 starts to get comfortable at 12 o'clock on volume pot. at 3PM it gets very loud, even on records which are mastered to be soft. Perhaps I have not feed the O2 something challenging that will expose it's limits driving O2.
post #11 of 32
Thread Starter 

I think a previous poster had a valid point i.e. even if the O2 can only fully drive the T1 to 110-115 dB at all frequencies, that's still extremely loud. Should we even be listening at volumes higher than this?

post #12 of 32
Quote:
Originally Posted by PTom View Post
 

I think a previous poster had a valid point i.e. even if the O2 can only fully drive the T1 to 110-115 dB at all frequencies, that's still extremely loud. Should we even be listening at volumes higher than this?

See items marked in bold....this is exactly the point I would like to make and a dangerous assumption if you link it to peak SPL attainable.  But I'm going to leave it at this.

post #13 of 32
Thread Starter 

I see so your point is that even if if the O2 can drive the T1 to loud volumes it might not be able to match its speed i.e. quick changes in frequency/volume?.


Edited by PTom - 2/25/14 at 1:16am
post #14 of 32
Quote:

Originally Posted by PTom View Post

 

Therefore there is just enough power and voltage to drive the T1 to 120 dB at an impedance of 600 ohm but at certain frequencies with very high impedances (i.e. 1400 ohm) it will probably not supply enough power.

 

That is not correct. Most headphones and speakers are designed to be driven by a voltage source, which has (ideally) zero output impedance. That is also how frequency response measurements at sites like innerfidelity.com are made. Therefore, higher voltage at the resonance frequency of the driver is not needed (unless you specifically want a colored sound with some bass boost). While the power at that frequency will indeed be lower, this is balanced by the increased efficiency of the driver near its resonance frequency; ultimately, you are listening to sound pressure, rather than Watts.

post #15 of 32
Quote:
Originally Posted by Xenophon View Post
 

this is exactly the point I would like to make and a dangerous assumption if you link it to peak SPL attainable.

 

So, what do you want a minimum power requirement to be linked to that can be objectively well defined ? Higher SPL requires more power (2x for every additional +3 dB), that is simple physics. Of course, "high end" audiophile amplifiers might have other, esoteric or paranormal advantages (other than perceived improvements resulting from easily proven psychological biases), but since you are on a forum called "Sound Science", it would be best if you could explain and preferably prove them.

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