Drive level for headphone?

[jan.didden]

Guys, I'm new to headphones but would like to dabble in HP amps.

I know there are many different headphone impedances, from 32 ohms to 600 ohms, maybe even more.
What sort of signal levels do these things want to make your ears bleed? I see numbers of xx mW but I guess it depends a lot on the headphone impedance.

Any pointers?

Jan

 

[abraxalito]

I find 2VRMS gives a reasonably loud listening level for most mid-level impedance (50 ohm up to 300) HPs. My DT880s are 600 ohm but also lower sensitivity so really need 6VRMS.

Planars need a bit more grunt as they tend to be at the lower end of the efficiency spectrum.

 

[nironiro]

If you really want that high levels, easier way is to use resistor around 330 Ohms in series, from speaker outputs of your amplifier.
Most vintage amplifiers use that, that was the time before dedicated phones preamps.

 

[jan.didden]

I'm not interested in specific implementations at this point, I want to know what is needed to make an intelligent decision. That was my question (see post 1).

Jan

 

[nironiro]

I know, but for me that is the most intelligent decision, but I appreciate that everybody has his own opinion.
Back in the glory days of HiFi, there was no separated phones preamps, every stereo amplifier had phones output. And that works great.

But I understand that is challenge to make dedicated phones preamp, after all we are on DIY site!

 

[jackinnj]

SPL per mW -- 2V RMS with my Sennheiser HD650's would be ear-splitting -Z= 300 Ohms. I have Stax from the 1990's -- have no idea what the drive level is as they work off a transformer which provides the bias. They sound great but I find myself using the Senn's all the time.

Low source impedance ~= low power loss.

 

[Pano]

There was a rather good estimation by one of our regulars in this forum a while back. I'll try to find it. Abrax's voltage numbers look generous enough to me. And planars do need a bit more kick.

 

[DontHertzMe]

I've found this spreadsheet very useful in the past: https://robrobinette.com/images/Audio/Headphone_Power_Calculator.xls

Type in the headphone impedance, sensitivity and desired SPL and it calculates necessary power / voltage / current.

Courtesy of Rob Robinette (Headphone Power Calculator Spreadsheet | Headphone Reviews and Discussion - Head-Fi.org). He also released an Android app.

 

[nironiro]

Many headphones have limited power that can handle, so before they goes to ears bleed volume they will probably burn out.
For that high volume best would be DJ headphones, they can handle 500mW to 1W.
HiFi phones will burn out before ears bleed volume.

 

[jan.didden]

That is a very nice spreadsheet DHM, thanks for the link!

Jan

 

[DontHertzMe]

That is a very nice spreadsheet DHM, thanks for the link!

Jan

Glad to be of assistance! Now I'm curious to see what the mighty Jan Didden comes up with

 

[Pano]

My AKG 4 channel headphone amp claims max 100mW. Output impedance 11 ohms.
I've also use the TI headphone chip TPA6120A supplied with +/-15V. Way more level than I ever need - but I have not tried it with 600 ohm cans. I have run 16 ohm compression drivers with it.

PRR Paul had some numbers here:
Best Headphone Amp IC today?

 

[Pano]

Yes, good link to the spreadsheet. Very handy!

 

[nironiro]

Found this on the net, calculating power requirements for ears bleeding 120dB:

Headphone Sensitivity / Power Requirements Compared | Headphone Reviews and Discussion - Head-Fi.org

But for some headphones, like Sennheiser HD650 there is no power rating data in the specification, so it is not sure that can handle 167mW.

 

[Pano]

With the spreadsheet I can see that 2V will get me 111dB on my rather low sensitivity Fostex cans. More than enough for me.

 

[jan.didden]

That's also a very good list, thanks. It does mean it is hard to build something that is optimum for everything.
Except maybe a chip amp for headphone use ;-)

Jan

 

[nironiro]

Yes, problem is that every headphones is specific, it would be best to first knows specification of phones, and than build amplifier for that specific phones.

 

[Pano]

Once I started using the TPA6120A chip, I never looked back. IMO to build one's own would be for fun only, not for improved SQ.

 

[jan.didden]

Yes, problem is that every headphones is specific, it would be best to first knows specification of phones, and than build amplifier for that specific phones.

That's what I tried to tell you a few pages back ;-)

Jan

 

[BesPav]

That's also a very good list, thanks. It does mean it is hard to build something that is optimum for everything.

Yes, clearly.
There are four main cases.
1. Usual box-in headphones. Dynamical, ~16-32 Ohms, ~100-110 dB/mWt sensitivity.
2. Full-size over-ear, 64-600 Ohms, 100-110 dB sensitivity
3. Full-size inefficient, 10-64 Ohms, 85-90 dB sensitivity.
4. Armature, in-ear and hybrids, 10-64 Ohms, >110 dB sensitivity.


(2)While high-impedance ones no need much current, but could demand voltage headroom up to 10-20 volts, current are low, say up to 50-100 mA.
(3)Inefficient ones require both voltage and current headroom up to ten volts and up to half Amp.
(4)Highly-sensitive ones doesn't demand huge swing, but especially sensitive to amps noise and could demand some current if resistance are low, say up to 1 Volt and 100 mA.
(1)Common droplets are somewhere inbetween and needs some dozens of mV to be driven, so, say, again up to 1 Volt and up to 100 mA.

Join 1+4 pair if you can provide low-noise, and add voltage or current steroids for 2 and 3 cases.

Also, keep in mind peak-factor and some, say, 6 dB margin in case of high-dynamic range music material.

Usually users can heat up to some minutes and then roll back volume. This allows to feel the power or saturate emotions.