Headphone amplifiers and high impedance headphones

[MRC01]

peaks are ms not seconds. ...

Sure, but how often do they happen? How frequently would a brief (say 100ms) peak have to occur, with what duration of quieter levels between the peaks, before it becomes an issue?

For example someone might feel safe playing a movie with peak levels this loud, with average levels in the 80 dB range. But then you reach a scene with explosions, gunfights or other loud noises... those can run for several minutes. Typical movie theaters play this loud (not than anyone has been to one recently!) and it makes my ears ring after the movie is over. Much too loud. It seems to affect everyone else's hearing too because when the movie is over they're all talking with raised voices like their hearing is suppressed from 2 hours of excessive loudness.

I find those kinds of levels to be excessively loud, unnecessary for musical enjoyment, and potentially harmful to hearing. I wear musician's earplugs when attending movies.

 

[tomchr]

Correct... if the 97dB/mW assumption is correct.
However, my table says it is 94dB/mW and 96dB/V.

Ah. That changes things a bit. So math:

115 dB SPL: P = 10^((115-94)/10) = 126 mW.
120 dB SPL: P = 10^((120-94)/10) = 398 mW.

Now, these numbers are for 600 Ω, so to fully address OP's question: You'll need an amp that can provide twice that power into 300 Ω. I.e. 250 mW into 300 Ω for 115 dB SPL or 800 mW into 300 Ω for 120 dB SPL. Many amps can deliver 250 mW into 300 Ω, few can deliver 800 mW.

Tables are great, but it's usually less work for me to just do the math. I keep a python shell open on my Mac for that exact reason. I also encourage anyone interested to learn the math so they can gain an understanding of the problem and won't get stuck if their headphones aren't listed in the table. But each to his/her/their own.

Tom

 

[Mile]

Correct... if the 97dB/mW assumption is correct.
However, my table says it is 94dB/mW and 96dB/V.

I was looking at this table from NwAvGuy all the time and I guess I got confused. Somehow I got the 97 from the NwAVGuy table.

https://nwavguy.blogspot.com/search?q=more+power+


No unit ist given, but it is very likely the 96db/V.

 

[tomchr]

Lots of specs, yet so much ambiguity. What's with the 32 Ω, 250 Ω, 600 Ω? Is it switch-selectable? Rated power of 100 mW. Into which impedance? And, yes. 96 dB. 96 dB/V? 96 dB/mW? Into which impedance?

At least they were capable of measuring the length of the cable, weight of the headphones (sans cable), and estimate the clamping pressure...

Tom

 

[hmscott]

Lots of specs, yet so much ambiguity. What's with the 32 Ω, 250 Ω, 600 Ω? Is it switch-selectable? Rated power of 100 mW. Into which impedance? And, yes. 96 dB. 96 dB/V? 96 dB/mW? Into which impedance?

At least they were capable of measuring the length of the cable, weight of the headphones (sans cable), and estimate the clamping pressure...

Tom

They are different SKU's - versions - of the same headphone. A 32ohm version, a 250ohm version, a 600ohm version, very common with Berydynamic to have multiple impedance versions of the same headphone. I've got several of them and they range from 16 ohm to 250 ohm to 600ohm, each a fixed impedance for each headphone.

I need help from the knowledgeable people here. If I want to drive a high impedance headphone, e.g. DT880 600 Ohm, what output power should my headphone amplifier have?

The DT880 600 Ohms has a sensitivity of 97db. According to this chart you would need 63 mW to drive the 880 with 600 Ohms with max output.

https://nwavguy.blogspot.com/search?q=more+power+

More or less any headphone amplifier discussed here , Objective2, Atom, Lake People 109, can do that.

Are there headphones on the market that are even higher in impedance? Does it make sense to look for a headphone amplifier with more output power? So I don't have to buy a new headphone amplifier when I might want to buy high a headphone with even more impedance than one of the 600 Ohm Bayers in the future.

I've got the same question, how to best drive the 600 ohm versions of Beyerdynamics. My DT990 takes 100% in H Gain on the Topping A90, and the DT880 has a little more sensitivity and I can back off to 3 oclock on the A90 volume dial, about 75% output of the A90 - H Gain on the A90 and full output from the D90 MQA set in Pre mode = DAC mode - full output.

I'm first trying an inexpensive Tube Hybrid AMP - the xDuoo TA-20 which has the option of running 2000mw into SE 6.35 or 2000mw into 4-pin XLR headphone connections:
https://www.xduoo.net/product/xduoo-ta-20/

• Output power: Phone: 2,000 mW (32 ohms); XLR: 2,000 mW (32 ohms)
• Frequency response: 10 Hz–100 kHz (+/- 1 dB)
• Gain: +18 dB
• Distortion: ≤ 0.01% (1 kHz, 32-ohm load)
• Signal-to-noise ratio: 115 dB
• Headphone impedance: 8–600 ohms
• Footprint: 5.8 x 8.3 in (14.8 x 21 cm)
• Weight: 3.4 lbs (1.55 kg)

The TA-20 is supposed to drive Beyerdynamic 600 ohm headphones "adequately". The TA-20 will be here in a week or two - my TA-20 is coming from Hifigo in China via expedited shipping (Fedex/DHL?).

And, I'm currently picking from a number of nice tube pairings for low noise, wide sound stage, and tight bass. audiotubes.com - Brent has been very helpful. There are a lot of reasonably priced choices, and some over the top priced choices - mostly based on rarity which doesn't necessarily translate into sound quality.

Xduoo told Hifigo that the TA-20 can use 12AU7, 12AX7, 12AT7, and 12BH7 - there are many variant numberings for compatible tubes within those base configuration id's as well.
http://www.audiotubes.com/12au7.htm

The audiotubes.com 12AU7, 12AT7, and 12AX7 pages have lots of variant numbering information, click on the tube base ID in the banner at the top of the page for detailed information. Even if you aren't going to get these tubes right now, it's a great walk through world history of tube manufacturing details. Brent has been gathering detailed hands on information for a long long time. audiotubes.com also has a Youtube channel where he does explanations of what to look for and how to identify various tubes:
https://www.youtube.com/channel/UCIGQDUXm67v44o6E7wXUGkQ

I will be happy to come back and share as to whether the TA-20 has enough Umph to drive my DT880 and DT990 600 ohm headphones.

And, yes I've read @amirm's review of the TA-20, it's a tube amp with stock cheap Chinese Tubes, what else would we expect?

From the owner reviews I've read I expect extremely satisfying melodious audio sounds to emanate from the pairing of the TA-20 with my 600 ohm Beyerdynamics with new low noise tubes, providing enough drive to fully enjoy 600 ohm headphones.

I'm picking "Medical, Scientific, Aerospace grade" tubes to replace the cheap Chinese new stock tubes, hopefully the quietest testing tubes will reduce the noise floor enough to enjoy my most sensitive IEM's as well as the 600 ohm Beyerdynamics headphones.

 

[tomchr]

They are different SKU's - versions - of the same headphone. A 32ohm version, a 250ohm version, a 600ohm version, very common with Berydynamic to have multiple impedance versions of the same headphone. I've got several of them and they range from 16 ohm to 250 ohm to 600ohm, each a fixed impedance for each headphone.

Interesting.

I've got the same question, how to best drive the 600 ohm versions of Beyerdynamics. My DT990 takes 100% in H Gain on the Topping A90, and the DT880 has a little more sensitivity and I can back off to 3 oclock on on the volume dial, about 75% output of the A90.

Holy crap!! Usually 2 o'clock is about -6 dB on the volume pot. 3 o'clock is probably -3 to -4 dB. That's basically running the amp flat out. What's the output level of your source?
No wonder people are aiming for that elusive 5 W into 50 Ω for their headphones...

That amp is supposed to drive Beyerdynamic 600 ohm headphones "adequately"

I'd be interested in your findings.

Tom

 

[NTK]

...
At least they were capable of measuring ... and estimate the clamping pressure...

Tom

But to what size head?

 

[brimble]

Are there headphones on the market that are even higher in impedance?

Yes, some are over 100 kΩ! But they need special-purpose amplifiers.

 

[tomchr]

But to what size head?

LOL. Good point. That's where the "circa" comes in.

Tom

 

[Mile]

Yes, some are over 100 kΩ! But they need special-purpose amplifiers

Just out of curiosity, give an 'example.

 

[Rock Rabbit]

Ah. That changes things a bit. So math:

115 dB SPL: P = 10^((115-94)/10) = 126 mW.
120 dB SPL: P = 10^((120-94)/10) = 398 mW.

Now, these numbers are for 600 Ω, so to fully address OP's question: You'll need an amp that can provide twice that power into 300 Ω. I.e. 250 mW into 300 Ω for 115 dB SPL or 800 mW into 300 Ω for 120 dB SPL. Many amps can deliver 250 mW into 300 Ω, few can deliver 800 mW.

Tables are great, but it's usually less work for me to just do the math. I keep a python shell open on my Mac for that exact reason. I also encourage anyone interested to learn the math so they can gain an understanding of the problem and won't get stuck if their headphones aren't listed in the table. But each to his/her/their own.

Tom

Add 100 mW of power handling as limit for DT 880 600 ohm

 

[brimble]

Just out of curiosity, give an 'example.

I think all electrostatics are around that. Certainly the ones I've looked up are. And that's why electrostatics come with their own amplifiers.

 

[RayDunzl]

I think all electrostatics are around that. Certainly the ones I've looked up are. And that's why electrostatics come with their own amplifiers.

Electrostats have their own amplifiers because the amplifier must provide several hundred volts of "static charge" on the diaphragm, and unless a step-up transformer is used, many (hundreds?) of volts of "signal".

Some electrostatics can use the signal to "self charge" via rectification, as a variation on the above, but still, high voltages are required.

https://en.wikipedia.org/wiki/Electrostatic_loudspeaker

 

[solderdude]

Tables are great, but it's usually less work for me to just do the math.

Looking at the table reveals the various impedance versions of the same type

And, yes. 96 dB. 96 dB/V? 96 dB/mW? Into which impedance?

Good question. It took me quite some time to calculate the numbers in my table from various 3rd party measurements and data sheets as well as my own measurements. Often dB/mW, dB/V is not given.
it's 96dB/mW in this case ,if it were in dB/V it is impossible due to them all having quite a difference in voltage sensitivity.
The problem with the manufacturer specs is they are measured differently than what Tyll does and some others. Measurements of 3rd party says it is closer to 94dB/mW (probably measured at 1kHz).

I've got the same question, how to best drive the 600 ohm versions of Beyerdynamics.

Topping is working on a version specifically for the 600 Ohm versions.

Balanced amps won't help here because the DTxx0 all have fixed cables and are SE. Those with 4 wire cables (some older ones I believe could be reterminated with balanced plugs.

I rarely toot my own horn but G1217 Ember and Polaris have high enough gain and can provide 400mW in 600 Ohm.

I think all electrostatics are around that. Certainly the ones I've looked up are. And that's why electrostatics come with their own amplifiers.

Impedance varies with frequency, chances are the line-in impedance of the energizer may be that impedance resistance.
Electrostatics (not electrets) need a high bias voltage and symmetrical drive of a quite high voltage and that's why they need energizers. It can also be a transformer connected to a speaker amp b.t.w.
See @RayDunzl reply.

 

[hmscott]

Looking at the table reveals the various impedance versions of the same type
Topping is working on a version specifically for the 600 Ohm versions.

Balanced amps won't help here because the DTxx0 all have fixed cables and are SE. Those with 4 wire cables (some older ones I believe could be reterminated with balanced plugs.

The xDuoo TA-20 also has an SE output, both are rated at the same 2000mw output into the same 32ohm load. There is no need to rewire the Beyerdynamic headphones to get higher output from the TA-20. Measured output shows XLR output is still higher on the TA-20.

Topping and FiiO among others have higher output for the Balanced output than the SE output, so with my A90 I prefer using balanced cables.

I was thinking of re-wiring all of my SE headphones as balanced, but after totaling up the cost of re-wiring and re-cabling I used that total to instead look for a second AMP that would drive the high impedance SE headphones without the need for re-wiring them. I wasn't interested in duplicating or replacing my SS amp, and I was already pre-disposed to get a Tube amp for SE dynamic headphones.

It's cheaper to try the TA-20 + Tube roll to get the sound - quiet low noise, dynamic, tight bass + details - than it is to re-wire all of my SE headphones for balanced. And, maybe with the right tube pair I can use some of my balanced headphones with the TA-20 too.

 

[FrantzM]

Get the JDS Lab Atom and be done with most any widely available headphones ...

 

[Rock Rabbit]

The xDuoo TA-20 also has an SE output, both are rated at the same 2000mw output into the same 32ohm load. There is no need to rewire the Beyerdynamic headphones to get higher output from the TA-20.

Topping and FiiO among others have higher output for the Balanced output than the SE output, so with my A90 I prefer using balanced cables.

I was thinking of re-wiring all of my SE headphones as balanced, but after totaling up the cost of re-wiring and re-cabling I used that total to instead look for a second AMP that would drive the high impedance SE headphones without the need for re-wiring them. I wasn't interested in duplicating or replacing my SS amp, and I was already pre-disposed to get a Tube amp for SE dynamic headphones.

It's cheaper to try the TA-20 + Tube roll to get the sound - quiet low noise, dynamic, tight bass + details - than it is to re-wire all of my SE headphones for balanced. And, maybe with the right tube pair I can use some of my balanced headphones with the TA-20 too.

https://www.audiosciencereview.com/...be-balanced-headphone-amplifier-review.10118/
instability in one channel vs frequency response, IMD 40 dB worst than a 789 amp (and that's with 100 mV input for "best" case), full power at 2% distortion independent of load ...SINAD 41 good for 16 bits

 

[solderdude]

The xDuoo TA-20 also has an SE output, both are rated at the same 2000mw output into the same 32ohm load. There is no need to rewire the Beyerdynamic headphones to get higher output from the TA-20.

It's 150mW in 600 Ohm.
Good enough to play loud enough (100mW continuous rated so can handle peaks of at least 400mW)
The high distortion is not of any audible consequence though.

 

[Mile]

Ah. That changes things a bit. So math:

115 dB SPL: P = 10^((115-94)/10) = 126 mW.
120 dB SPL: P = 10^((120-94)/10) = 398 mW.

Now, these numbers are for 600 Ω, so to fully address OP's question: You'll need an amp that can provide twice that power into 300 Ω. I.e. 250 mW into 300 Ω for 115 dB SPL or 800 mW into 300 Ω for 120 dB SPL. Many amps can deliver 250 mW into 300 Ω, few can deliver 800 mW.

The Lake People 109 would be an option. The downside is that you can only change the gain via jumpers. Who wants to constantly open the housing to adjust the gain?