Hi everybody!

I got my CLP785 in October and I gotta say I'm very happy with it so far.
There's just one thing baffling me, so I'm wondering if others are dealing with the same issue.

I tested the headphone jack with multiple different headphones now:

1. Austrian Audio Hi-X55 (Studio headphones, 25 Ohms)
2. Shure SE215 (in ear) (17 Ohms)
3. Beyerdynamic DP770 PRO (32 Ohms)
4. Beyerdynamic DP770 PRO (80 Ohms)

The problem is that only number 1 and 2 are able to produce output I actually consider to be "loud" (still far from hurting my ears though at 100% volume piano-wise).

32 Ohms and even more so 80 Ohms seem to be too much, the volume at 100% doesn't even reach a "sweet spot" if played softly -
and I just can't understand why that should be intended for an instrument being priced like that.

Do you experience the same issue?
Is there any internal tweak to be made to fix this?

To me this really is a problem, since there are quite few headphones on the market which are below 32 Ohms, but produce decent sound.

32 Ohms are considered to be industry standard even for mobile devices, so I was astonished to learn that the instrument isn't able to deliver sound loud enough.

I was able to test this on a CLP635 a while ago - it was much louder using headphones 1 and 2 of above list, so there doesn't seem to be a technical barrier or anything wrong with the headphones itself.

Best regards from Vienna,

Lukas

Yeah I ran into this as well. I have a 50-70 Ohms high-end headphone, but it's just not loud enough on the 785. I manage, but it's not great. There is only one solution if you want to use higher impedance headphones: use a headphone amplifier. Are you sure the 32 Ohms isn't loud enough though?

Ok, that's quite disappointing..

Yeah.. It's "loud enough" - I can hear everything I play.
The thing is, if I want to have my brain washed away while playing lower impact pieces, it actually isn't loud enough and nowhere near to the volume level you would get from an actual acoustic piano.

At least I know it's not just my model, maybe I really need to buy low-impedance headphones then..
What I didn't try so far is to use headphones with a higher sensitivity while still using 32 Ohms, maybe that's worth a shot (Beyerdynamic with about 96 db is on the lower end here as far as I know).

WARNING: School lesson follows.

"Impedance" = "resistance to electrical current flow". The higher the current flow the higher the power (also known as "watts").

For direct current, such as that supplied by a battery, the resistance to electrical current flow is a constant. 32 ohms is 32 ohms is 32 ohms.

For alternating current, whether it's coming out of the outlet on the wall of your home or whether it's sound coming out of the headset jack or speaker jack, the "impedance" increases as the frequency increases when coils are involved.

A speaker's impedance is usually measured at 400 hertz (Hz) while headsets usually are measured at 1,000 Hz. That 32 ohms measured at 1,000 Hz will be higher at 2,000 Hz and higher yet at 3,000 Hz etc.

For maximum efficient power transmission from the amplifier to the headset (or speaker) the impedances should match. A 32 ohm amplifier should have a 32 ohm headset plugged into it.

If the amplifier is designed correctly, it also will deliver power on an increasing curve. The designer knows that the higher the frequency the more power the amplifier must deliver because the resistance to electrical current flow increases and thus the power delivered to the headset coils decreases. Otherwise, the higher the sound frequency the lower the volume coming out of the headset.

If you use a lower impedance headset than the amplifier is designed for, the current (power) pulled from the amplifier increases so the volume increases at the same volume control setting. But the lower impedance can appear as closer to a short circuit to the amplifier circuitry. That can either damage the amplifier or more likely, damage the coils in the headsets if pushed too far.

If you use a higher impedance headset than the amplifier is designed for, the current (power) pulled from the amplifier decreases because the amplifier is expecting a lower impedance. That results in a lower volume at the same volume control setting.

Modern electronics usually can handle a limited range of impedances without damage as long as it's not pushed too far power-wise. But if you have an amplifier designed to match a 250 ohm headset and you plug in a 25 ohm headset, the amplifier is seeing a device that is a whole lot closer to a short circuit because the headset presents only 1/10th of the electrical resistance that the amplifier was designed for. That can result in a current flow of 10 times more at the same volume setting.

In the (not so) good, old days, it was not uncommon to blow up an amplifier designed for 16 ohm speakers by installing 3.2 ohm speakers. Or installing multiple 3.2 ohm speakers in parallel.

For what it's worth, the manual for the CLP-635 and the CLP-785 both list the same optional headsets:

HPH-50 = 35 ohms
HPH-100 = 46 ohms
HPPH-150 = 48 ohms

I also would not be surprised to learn that the manufacturers are artificially limiting the overall power delivered to the headsets due to lawsuits about hearing damage. The 635 was launched in mid 2017.

I hope this helps explain what you're experiencing rather than adding to the confusion.

Ray

It's almost right. Two issues:

1. It (implicitly) assumes that all headphones have the same efficiency (or "sensitivity") -- that a milliwatt of electrical power sounds as loud in headphone A, as in headphone B.

My Senn "HD280 pro" is stamped "64 ohms". My AKG K240 Studio is stamped "55 ohms" -- not significantly different.

. . . But the HD280 is significantly louder than the K240.

2.
I don't know how much the inductance of the headphone-coil winding contributes to the headphone's impedance. And I'm reasonably sure that normal amplifiers (including headphone amps) are not built with frequency compensation that increases their gain, as the signal frequency increases:

. . . the good ones measure flat (voltage gain vs frequency), into a resistive load.

I've noticed a similar difference between the CLP 575 I've had previously and the 785.

I have the AKG K702 (62 Ohms) and the Beyerdynamic DT 131 (40 Ohms).

The Beyerdynamic is clearly louder via headphones. Luckily the AKG is still loud enough for me.
I remember having tested the Casio GP510 which was unusable with the AKG.

Blame it on the iPhone. In the old days home amplifier equipment mostly required 80 Ohms or higher for headphones for optimal response - now iPhones work best at around 32 Ohms so its not hard to guess why digital pianos have had to "comply".

Thanks for your replies.

I think it's an interesting decision to design the headphone jack like that if you consider the price you pay and by that the quality you'd expect.

I wrote to Yamaha Support about this - I don't expect them to be able to do anything about the impedance story, but who knows what kind of volume reducing software might be in place.

If they provide any fix, I'll let you know, but I guess I'll just have to get to know all the <25 Ohms headphones out there to find something suitable sound-wise.

I use Beyerdynamics DT-770 PRo 250Ohm and Sennheiser HD580 without issues, although I need to keep the volume at about 95 or 85% respectively for these headphones.

The issue is helped by changing the voice volume from 100 to 127 by going to menu Voice > Voice Edit > Volume.

The is enough headroom for one instrument to be at 127 volume without any clipping (this volume change is in the digital domain - 127 is normal volume. 100 is reduced volume. Yamaha does did this even on my MU100R rompler from late 90s). It would only be an issue if you stack multiple instruments and run out of headroom.

If you are not stacking multiple instruments, this will not cause any clipping. If it did, it would be a very obvious awful digital clipping sound.

Thank you so much! This is a big improvement for me. It's still not an ear-shattering volume, but the sound has a lot more body and is a lot more fun to play.

Another thing I should mention, since the thread focuses on impedance... my understanding is that efficiency is going to determine how loud different headphones get, and many low-impedance headphones are very inefficient. This article may help.

https://www.headphonesty.com/2019/04/headphone-impedance-demystified/

Solid State power amplifiers, whether for speakers, or included in the digital piano for headphones, are extremely low impedance devices (typically a few hundredths of an ohm). Their purpose is to provide current (not voltage, which is electromotive force) to create a magnetic field in the voice coil, moving it so that it moves a mass of air. Doubling the impedance of a voice coil halves the output power, which is why amplifiers often specify power output at both 4 and 8 ohms. All this is moot however, if the power supply cannot provide enough current to the amplifier to adequately drive the voice coil, or the amplifier has a built-in current limiter to prevent overheating.

The sensitivity of the headphones, usually measured in dBm (0dBm = 1 milliwatt), is the best measure to include along with the rated impedance of the headphones. Choosing headphones with a rating of 104dBm vs. a rating 101dBm will sound equally loud when only half as much power is delivered to the 104dBm phones.

That's true. But impedance comes into the discussion in a fundamental way:

. . . A high-impedance headphone may be very efficient (lots of dB per milliwatt),

. . . . . but delivering those milliwatts is difficult for an amp that's "voltage-limited" -- for example,
. . . . . . a battery-powered amp in a portable device.

_Both_ the current- and voltage-limits of the amp (or its output impedance and maximum power) come into play. And neither one is usually supplied by the DP manufacturer.

My Shure SE215 "in-ear monitors" are rated at 17 ohms. They work well with battery-powered phones and laptop computers. The sensitivity is given as
which is pretty loud, even with a smartphone.

Of course, being in-ear devices, the diaphragm only has to move a tiny bit of air, to generate lots of dB's of SPL.

Yes, this is correct, regarding voltage-limited devices. The problem here is the same as I discussed above. The power supply (a battery, which has internal resistance which lowers its voltage when heavily current loaded, and thus not able to deliver as much current as required), or an AC power supply, must be rated to deliver sufficient current. Most amplifier power supplies have large capacitors to provide short-lived (a few milli-seconds) large values of current above the continuous current rating.

Just a quick point. dBm is the ratio of Watts to 1 milliwatt, dBV is the ratio of Volts to 1 Volt, dB SPL is the ratio of Sound Pressure Level at a given point (very very different from dBm) to 20 microPascals. Normal atmospheric pressure is about 101,300 Pascals.

In spite of what the internet says about amplifiers, they do not deliver volts. That would like saying that a battery delivers volts. They don't. They deliver current. A 12 volt battery, or a 120,000 volt power line deliver only one thing - current, and they do that only when there is a load (resistance or impedance), otherwise the voltage (pressure) just sits there doing nothing. Voltage is force.

I should correct a misstatement I made above. Power amplifiers do not deliver volts.

I design and use daily voltage amplifiers. They are used in practically every pre-amp, microphone amp, and instrumentation amplifier. For all practical purposes they provide electrical potential, whose electrostatic field provides for controlling the current flow in a power amplifier, and do so without consuming power (not much at any rate) themselves.

Might one ask what devices are not voltage-limited ?

I think the plate voltage on a 25KW lowband TV transmitter where I worked in the 80s was 17 KV... which is still "limited" (although highly lethal).

In the vacuum tube era, where amplifiers generally had a couple of hundred Volts B+, headphones were often in the range of 2,000 Ohms. (At the opposite end of the voltage scale, crystal receivers also required 2K or higher headphones so as not to load down their circuitry).

As everyone in this thread has pointed out, a higher impedance load requires higher voltage to generate power (similar to E-squared over R in a DC circuit).
Interfaces such as the Focusrite that are driven from a 5 Volt USB connector are limited as to their voltage swings since they don't include circuitry to boost that voltage. An AC-powered instrument is not inherently limited, but is probably designed based on what the majority of consumers purchase.

As to the OP's original question... assuming that you own all those headphones you've tested, it would seem a lot more economical to buy an AC-powered headphone amplifier to give you enough drive to run them properly.

Wow, this does indeed make a huge difference - I never saw this setting, thanks a lot for pointing it out!



I don't own them, these are just the ones I could borrow for testing / "buy" and return.

I tested the above (127 volume) with DT770 32 Ohms and it isn't even necessary to go to either 127 or max volume on the instrument.

This opens a lot more possibilities, impedance about (I guess) at least 80 Ohms should now be "loud enough" for most of the people.

Thanks a lot to everybody for your contribution, also for adding details about the technical background - this thread should be of great help for anyone dealing with similar "issues".

Have a nice day and enjoy your DPs as much as you can!

We could have a whole new thread here. Thanks for responding and revealing my limitation of language use.

Perhaps I should have said: 'All devices are voltage-limited, some are just more limited than others.'

I am in the midst of designing a Class B RF push-pull power amplifier using an 829B output tube for SSB and CW use. Choosing the anode load impedance is limited by the power supply transformers I have on hand and how to design the power supply to deliver the required current at a voltage that is held constant to within 20% or so.

Incidentally, I use 2000-4000 ohm headphones for a number of tube radios I have built that use the headphones as the direct (transformerless) anode load.

Cheers.

LOL. And "all animals are equal but some are more equal than others."

For headphones as an anode load, a good blocking capacitor may save more than just your hearing...LOL...

Cheers!

73 de va7cpc

73 de VA3AZH

The headphones were often used as the RFC to the B+ supply, so no capacitor could be used. I have a few radios I designed that use 150H chokes to the B+ line, and a blocking cap to the headphones. I always feel a little concerned putting on a pair of cloth wrapped wired headphones with 90 volts across my cranium.

For what it's worth, I have a CLP 645 and I can use both a Sennheiser 600 (300 ohms) and 660S (150 ohms) with no problem, not having to even turn the volume all the way up but about 3/4. My Yamaha HPH-100 only needs about half volume or a little less. Incidentally, I can use both on my iPhone 12, admittedly though the 660S works better on that. Either Yamaha drastically changed the power output in the 700 series or there's a problem somewhere else. Bad connector/adapter?

I’m using Sennheiser HD600s.. 300 ohm. Bumped this up and helps, but still not as loud as I’d like at full. Should I be using an amp?

Most likely. Either an amp ----- or a set of headphones that has it's own onboard amp. I know that my Sennheiser HD 4.5 plugged into the digital piano audio socket doesn't sound too loud ----- but loud enough for me to play comfortably. This is in its 'unpowered' mode ------ as in audio power going in only, with no active circuitry being used.

And then ---- when I push a button on these head-phones to switch on the head-phones ----- the active circuitry ------ we can get louder, much louder. But I tend to not go for the loud ------ to cut down on chances of hearing damage etc.

With audio amps and head-phone combinations ----- it's probably a good idea to have it dialed down always .... to begin with. And then gradually wind up the volume to the desired level. We all know about that ear-drum blowing thing ------ where we get caught out by surprise if settings changed ---- or a setting got accidentally moved without us knowing.

Or the other way is to not put the head-phones on directly over the ears ----- and then gently push a few keys (each time we start up a new piano session) to do some audio level testing ----- just in case.

Hi Ray,

Correct me if I'm wrong, but I was under the impression that impedance matching between source and cans was to be avoided in favour of impedance bridging---where the impedance of the cans is much higher than the source impedance?

That's also mentioned here: http://forum.pianoworld.com/ubbthreads.php/topics/2616329/cheap-headphone-amp-recommendation.html

Some say 10:1 (where cans have greater impedance than the source), others seem to suggest 2.5:1 to 8:1.

I was looking into this today, so I'm keen to get other's views, as it's new to me...

I have two bits I copied over to keep:

So I'm interpreting the above to mean that ideally, the piano output impedance should be much lower than the headphone impedance.
Not sure Yamaha will state the output impedance even if you ask. What you might try: you could write them an email and ask what's the highest they'd recommend for the headphone impedance that the CLP785 could power??

Perhaps the OP needs something around 150 Ohm or above. I tried the CLP685 using Sennheiser HD650 (300 ohm) and they sounded good to me.

I think 'impedance matching' is probably not critical in audio applications. But in any case .... impedance matching is along the lines of ..... if you have a power source that has a fixed voltage .... and if the output impedance of the source is known .... then there is a known method for determining what the impedance of the load needs to be in order to get the maximum amount of power that can possibly be delivered to that load.

But when we don't have any choice about the load's impedance .... as in we had no part in designing that load's impedance ...... and we need to get some desirable amount of power into the load ..... then one way is to increase the voltage of the source .... provided that nothing like rated voltage or rated current or rated power of anything is exceeded.

Another way is to set the audio output of the existing system to a suitable output level ..... and feed that output to the input of a more substantial amplifier system. And then just manage the system so that the input never overdrives the system ..... as in avoid distortion and possible damage of anything by properly managing the system.

So any recommendation for something on the level of the 600s I use that will actually get up to too loud?

Tried using a VST and outputting the computer audio to the 785 and use the headphones… about the same level.. can’t get it too a point where you’d want to back off a little. So maybe not a limiter in the clavinova engine and it’s something with the headphone resistance?

Curt ------ I haven't got a head-phone amp yet ----- but was doing some online searching yesterday and came across one of Sony's - which is probably more than what we need in general, the TA-ZH1ES ---- relatively expensive too ------- but I can see other brands such as Schiit Audio Magni 3+.

Excuse the language, but that's what their site says ------ as in Schiit happens etc. Blame it on them.

I think that ----- for some of these modules --- just need to get a suitable adapter cables in order to connect the output audio socket of the digital piano to the input audio socket(s) of the amplifier module. It most likely is straight forward ----- to just buy the appropriate adapter cable, or some people can get the parts to make up their own cable.

The Sony one has both balanced and unbalanced input and output options.

So send the 785’s Aux outs into something like these?

I had the same issues. This digital piano seems to work best with headphones that are 150 ohms or lower. I originally had the Sennheiser 650s (300 ohms) and had the same issue with a low volume. It was acceptable, but certainly not enough volume if it was loud outside or if I had other people in the house making noise as well. I had to use a headphone amp to really get the volume that I wanted. Ultimately, I moved to the Sennheiser 660s which are 150 ohms, and they give me great volume.

If you’re using the built-in sounds, and your headphones have high ohms or just give you low volume for whatever reason, you can change the internal mixer volume higher to give some extra volume. For some reason, the internal mixer is set at only 100% out of a possible 127%. so even when you turn the volume slider all the way to maximum, you’re still only getting about 80% of the possible volume. To change this:

From the touch buttons on the piano:
- Press the Menu button (three horizontal lines at the top left)
- While in the “Voice” menu, scroll down to “Voice Edit”, and select
- While in the “Voice Edit” menu, scroll down to Volume, and select

You’ll notice Volume is set to 100 out of a possible 127. Take the volume all the way up to 127.

That should afford you about 25% more volume. It’s definitely noticeable when you’re playing.

From the Smart Pianists app:
- Open the app, and make sure the piano is connected to the app.
- Click to the “Voice” menu button to access “Voice” section
- While in the Voice section, press the icon at the very top right of the app, that looks like piano keys with gears in front of them to access “Voice Setting” section
- At the left you should see two options, select “Mixer”
- Take the volume of the “Main Mixer” all the way up to the top. If you’re using layering or split keyboard, then take them all up

This should again take the volume to the full 127.

You’ll have to do this each time if you set if via the piano itself or the app. However, from the Smart Pianists app, if you save your settings, by pressing the Registration Memory button and assigning a name to your settings, you can easily recall those settings each time you log in. The Registration Memory button is with the group of buttons at the bottom left of the screen in the Voice section, to the right of the “Record” button, and looks like Drums, Piano, & Music Symbols in a semi-circle with an arrow pointing down under them.

This affords a bit of a volume boost, which is definitely helpful. Overall, though, this this digital piano seems to be best working with headphones that are 150 ohms or less. 300 or more, and you’re definitely going to need an app.

A Great & Inexpensive Amplifier:
For what it’s worth, when I was using the built-in sounds and the Sennheiser 650s which were 300 ohms, I found a very nice quality amplifier that was only about $49.99, and it boosts the volume amazingly, without losing sound quality. You can also add even more gain (although it’s not necessary because the built in volume on the amp is loud enough as is, and added gain and takes the volume to ear splitting levels) and even a “bass boost” is you want a bit more low depth to your sound. You can also control the volume with a volume knob on the amp to get it just where you want it:

Fosi Amplifier on Amazon

This amplifier did very well by me and I didn’t notice any discernible loss in quality from using the amp versus connecting directly to the piano.

Hope this helps.

That's it Curt. That's right. With any amp to be used ---- what you can do is to have your digital piano audio output dialed down to zero to begin with. Then set your external amplifier module's amplification to say 75% of max amplification ----- just for safety. And then very gradually wind up the digital piano audio level.

The aim will be to make the digital piano's own audio level high enough to get a nice signal --- with nice signal to noise ratio ---- so not too weak. But also not so strong that it exceeds the specified input levels of the external amplifier ---- otherwise it can lead to distortion and damage of something.

Yamaha CP88 here, can't drive Beyerdynamic 770 at any reasonable level. Internal amp of DPs are low quality as a general rule, kind of a shame given that this baby set me back 2k.

Long story short I got me a simple SMSL headphone amp https://www.audiophonics.fr/fr/ampl...-casque-2x13w-32-ohm-argent-p-15869.html and I am more than happy.

I ordered a Schiit Magni 3+, and some 90 degree TS to RCA adapter and RCA stereo cable.. I’ll see how it goes.

I did just try another VST and the headphones were really loud.. maybe the VST was just really jacked up vs Garritan or the internal 785 engine. Made me think it’s possible without the amp, at least with VSTs

I guess when I plug into the Aux it mutes the built in speakers? So a small pain to switch, but not much worse than plugging in the headphones

Nice one Curt. I'm sure your headphone amp will come in handy.

If there is no onboard setting for muting the built-in speakers, then a dummy head-phone jack (dummy jack without headphones) could be plugged into the digital piano's head-phone socket maybe ----- to get the muting.

Also ------ assuming the digital piano has a head-phones output (socket) ------ then a suitable cable that connects that output socket to the input of your head-phone amplifier -- can be used. And the head-phones then plug into the head-phone amplifier.

The aux is usually at the back of the digital piano (if there is one). And the head-phones socket is usually at the front of the digital piano. Plugging in head-phones will mute the onboard speakers of the digital piano.

I like the signal plug into the headphone jack and the assured muting of the speakers vs using the2 Aux ports and maybe no muting of the speakers.

I was worried the headphone jack might not work into the headphone amp and you needed some kind of pre-amp out and Aux was that.

Curt ----- true. The head-phone socket output of the digital piano will have a much higher voltage level waveform than the aux output waveform --- for a particular load.

So if this particular head-phone amp has instructions that direct us to link the aux output ------ then that's the way to go, and then just pop a dummy head-phone jack into the headphone socket (for muting the onboard speakers ----- that's if there's no setting in the digital piano console for muting the speakers).

Yeah I was thinking that… plus maybe amplifying any noise, not that Aux won’t have noise too.


There’s a setting to mute the speakers when using Aux, but that adds a step that’s more than plugging a dummy headphone plug. I’ll just always have Aux outs to my amp and headphones going and then pop in a dummy headphone jack to mute the piano’s speakers when I actually use the headphones.


Thanks!

Curt ----- I forgot to mention too ----- that --- head-phones output of the digital piano can still definitely work with the head-phone amp module. The difference is that ------ if we connect the head-phones socket to the amplifier module, then the volume output setting of the digital piano needs to be much lower than for the case where aux output is used. It's just due head-phone output levels being a lot stronger than aux output levels ----- just due to the design or standard etc.

Thanks! Aux is accessible, so I’ll go that road for a hopefully cleaner signal and dummy plug the headphone jack to mute internal speakers.

I appreciate the help

Most welcome curt!

Curt ---- some nice news. You have a CLP-785, right? If you use the head-phone amp module ....... and if you want to disable the onboard speakers, then just check out page 100 of the CLP-785 manual ------ which has a setting to disable the onboard speakers. The menu settings of the CLP-785 will have 3 options ---- normal, on, and off. Once you choose the 'off' option ----- this will disable the onboard speakers. And then you can just listen to the headphones from the amplifier module. This is nice ----- as it means no requirement for the dummy phone-jack.

(OT) @southpark Why all the dashes in your posts? Do you want to discourage people to read you? If so, it works.

Good question Ostinato. It's my way of adding pauses, sort of like a comma. But giving time for somebody to pause for a little bit longer than a comma.

So for my previous post, I began with "Curt ----- some nice news". To me, it's better than "Curt - some nice news" or "Curt, some nice news" or "Curt. Some nice news". Better ------- in my opinion that is.

Lives in a country where the local shop is 90 miles away, makes sense that he likes long pauses

hahaha. That is true. I'm on my pedal bike right now, with a dynamo generator to power my computer and modem haha. With saltwater crocodiles walking around outside on the streets hehehe.

Do croc's like Chopin or Chompin?

haha! Nice one Doug! They like both haha. When they go Chopin, they like to eat the customers!

Well, I have a hard time reading your posts with all the dashes —— they ——- prevent me from —— getting —— in a —— natural —- reading flow.

It's ok. You'll get used to it. I'm an internet veteran ----- maybe just like you. And I have posted a heap on many forums - aside from pianoworld. And everybody else has no issues responding to my posts, and they're able to read my posts comfortably.

Also, the locations of the dashes in your 'example' doesn't accurately reflect my style. You placed pauses in regions that are not meant to contain 'pauses'. If you know what I mean.

Here's an example of the incorrect way to do it (which is what you were doing - incorrectly).

If --------- you know -------what ----- I -----------mean.

And now, back to the topic of head-phones. I think I will order the same amplifier module that curt ordered. Seems pretty good for the price.

The Schiit went very well!