Sennheiser HD650 Review (Headphone)

[Oso Polar]

I have both the Qudelix and Fosi DS2. Both drive the 650 fine single ended.

Hmm, I have Qudelix-5K and HD *600*, I've changed cable to balanced in order to be able to get these few extra dBs, otherwise with EQ (with -5.5 dB preamp) max volume was quite modest. Even with balanced connection max volume is not too high - occasionally I do max out the volume during listening, so no reserve. I don't think that HD650 will be very different.

 

[MRC01]

I just got a used pair of HD650's after not owning them for awhile and found an old HD650 cable I made from Mogami 2543. I plugged it in and felt a possible improvement. The sound feels deeper, more clear, bigger but also slightly darker.

If there is any audible difference between the cables, which is an open question without a double-blind test, the way you describe it, sounding darker (less treble), the new cable could have high enough capacitance to slightly attenuate the treble. It's unlikely because it would take a lot of capacitance to cause this, perhaps using an amp with a high output impedance (such as a tube amp) would accentuate it.

I Googled Mogami 2543 cable and got this: https://mogamicable.com/category/bulk/microphone/quad/
Did you mean 2534? The specs linked there are confusing since they print 5 different capacitance values and say "partial capacitance" and "using standard testing methods of Mogami wire & cable corp". But the 5 values range from 4 to 110 pF per meter.

By comparison, a well engineered cable like BlueJeans LC-2 has about 35 pF per meter which is considered "low". That's desirable if you don't want your cables to modify the sound (the true definition of "transparent").
In light of this, even if the Mogami has the highest value of 110 pF per meter, it's nowhere near enough to attenuate the treble with any reasonable length of cable.

 

[olds1959special]

If there is any audible difference between the cables, which is an open question without a double-blind test, the way you describe it, sounding darker (less treble), the new cable could have high enough capacitance to slightly attenuate the treble. It's unlikely because it would take a lot of capacitance to cause this, perhaps using an amp with a high output impedance (such as a tube amp) would accentuate it.

I Googled Mogami 2543 cable and got this: https://mogamicable.com/category/bulk/microphone/quad/
Did you mean 2534? The specs linked there are confusing since they print 5 different capacitance values and say "partial capacitance" and "using standard testing methods of Mogami wire & cable corp". But the 5 values range from 4 to 110 pF per meter.

By comparison, a well engineered cable like BlueJeans LC-2 has about 35 pF per meter which is considered "low". That's desirable if you don't want your cables to modify the sound (the true definition of "transparent").
In light of this, even if the Mogami has the highest value of 110 pF per meter, it's nowhere near enough to attenuate the treble with any reasonable length of cable.

Yes 2534. I’m not sure if the sound was darker. I’m pretty sure I heard more bass though, which might create that perception.

 

[A Surfer]

Yes 2534. I’m not sure if the sound was darker. I’m pretty sure I heard more bass though, which might create that perception.

No, cables are not effecting the sound like this. There is no reason that they could.

 

[olds1959special]

No, cables are not effecting the sound like this. There is no reason that they could.

I did hear a difference but not sure if it's an improvement. I went back to the stock cable for now. It's fine.

 

[A Surfer]

I did hear a difference but not sure if it's an improvement. I went back to the stock cable for now. It's fine.

You thought that you heard a difference. That is not the same as hearing a difference.

 

[MAB]

Yes 2534. I’m not sure if the sound was darker. I’m pretty sure I heard more bass though, which might create that perception.

Hearing more bass in a sighted comparison is a sure sign you fooled yourself.
Of all of the things that don't change when you switch cables, bass is by far the least reasonable difference.

 

[olds1959special]

Hearing more bass in a sighted comparison is a sure sign you fooled yourself.
Of all of the things that don't change when you switch cables, bass is by far the least reasonable difference.

Yes, I temporarily thought the new cable was “better” during the honeymoon period. Honestly after putting the stock cable back it sounded less boomy or something I can’t describe. But I think I’m hearing the music more clearly now. There are definitely slight audible differences between the cables. I wrapped the extra length around my desk, so the stock cable is fine.

 

[MAB]

Yes, I temporarily thought the new cable was “better” during the honeymoon period. Honestly after putting the stock cable back it sounded less boomy or something I can’t describe. But I think I’m hearing the music more clearly now. There are definitely slight audible differences between the cables. I wrapped the extra length around my desk, so the stock cable is fine.

I fool myself on bass. It's so common. People commonly perceive changes in bass when none exist. Honeymoon period does exist though.

Regarding audibility, you would need to do a blind test. If you do, all of the differences will likely evaporate. If the differences don't go away, it will be a bit remarkable. You need an extreme corner case in your headphone and/or amplifier to actually have the impedance and parasitic of the cable matter. HD650 are not a corner case headphone, really unlikely that they are interacting with cable and amp in an audible way.

 

[olds1959special]

I'm using the HD650 with the stock cable with a MG Head OTL headphone amp and Tung Sol ECC803S and Genalex Gold Lion EL84's. The source is an SMSL DL200, Filter FL4 (linear phase fast filter), connected by 0.5ft WBC Mogami 2964. The sound is warmer than the Beyer Dynamic DT990 600 ohms I was previously using, allowing me to turn it up more with less fatigue but they will still make my ears ring if I am not careful and go too far! The sound is immersive and relaxed, but there is a slight sense of congestion I didn't get with my DT990's. It's not bad, just slight, so overall they seem like an improvement over the DT990, since they are not as focused in the treble region and still provide a good amount of detail. I'm happy for now, I think.

 

[olds1959special]

The 650’s sounded too congested for me with my OTL tube amp. I’ve gone back to the DT990-600ohms. I’m going to try the 650’s with a Topping L50 amp. I’m hoping the L50 changes the sound of the 650’s more towards clear and open. I want to like the 650’s. They are comfortable and seem to have potential.

 

[Robbo99999]

The 650’s sounded too congested for me with my OTL tube amp. I’ve gone back to the DT990-600ohms. I’m going to try the 650’s with a Topping L50 amp. I’m hoping the L50 changes the sound of the 650’s more towards clear and open. I want to like the 650’s. They are comfortable and seem to have potential.

You'd probably be better off not wasting your time trying to change the sound of your headphones using different cables & different amps and instead use parametric EQ to change the sound of your headphones whilst at the same time using "any cable" and a transparent good measuring amp (your Topping L50).

 

[FTB]

Hi there,

Does someone know how much mW are needed to drive well the HD650 ?
For me to know if a dongle is enough with something like 14 mW at 300 Ohms.

Thank you !

 

[staticV3]

Does someone know how much mW are needed to drive well the HD650 ?

For me, about 0.1mW suffice to drive my HD650 really well (85dB SPL Peak).

 

[solderdude]

Hi there,

Does someone know how much mW are needed to drive well the HD650 ?
For me to know if a dongle is enough with something like 14 mW at 300 Ohms.

Thank you !

The test below was done using the HD650:


The part of the recording shown below was playing very softly, think soft level when listening in the evening. The level where you can easily listen for a whole evening while having the urge to turn up the volume a bit.
This is slightly below the level I usually listen at. My ‘normal’ listening level is around 75dB average.

This resulted in the following (rounded off) numbers:

RMS levels = 23mV = 0.0017mW = 70dB (average)
Peak levels = 245mVPP = 87mVRMS = 0.023mW = 82dB
calculated DR = 11.5dB for that 10 sec of the song.

---

The plot below shows part of the recording was playing at a very comfortable level that is a fair bit louder than the soft level. You can listen a whole evening to this level. This is slightly above the level I usually listen at.
On lower DR recordings you like to turn it down a slight nudge, higher DR recordings you may feel the urge to turn it up a tad.

This resulted in the following (rounded off) numbers:

RMS levels = 75mV = 0.018mW = 80dB (average)
Peak levels = 830mVPP = 293mVRMS = 0.26mW = 92dB
calculated DR = 11.8dB for that 10 sec of the song.

---

The part of the recording below was playing at a comfortably loud level which is easy to listen to for 1 or 2 songs before getting the urge to turn it down to more comfortable levels.
When I really like a song I might turn up the volume to this level but turn it down again after 1 or 2 songs.

This resulted in the following (rounded off) numbers:

RMS levels = 236mV = 0.174 mW = 90dB (average)
Peak levels = 2.63VPP = 930mVRMS = 2.7mW = 102dB
calculated DR = 11.9dB for that 10 sec part of the song

---

This part of the recording below was playing uncomfortably loud. It is the type of level where you turn up the volume because you either like the song very much or want to listen ‘deep’ in the recording to evaluate.
Not a level you would gladly endure for the whole song.

This resulted in the following (rounded off) numbers:

RMS levels = 510mV = 0.81mW = 97dB (average)
Peak levels = 9.16VPP = 3.24VRMS = 33mW = 113dB
calculated DR = 16dB for that 10 sec part of the song
(this was the intro of the song by the way)

---

Here the music is playing at quite uncomfortably loud levels. One may use these levels for listening ‘in the recording’ for analytic purposes to check for distortions or find noise levels in the recording.
These levels are certainly NOT used for pleasantly enjoying music and one, for sure, cannot maintain to listen to these levels for the whole song.
It should be noted though that this is a DR13 recording and this particular part was ‘just’ 12dB DR.

When listening to DR20 recordings the average levels will be quite loud but the peak levels will reach about the same 117dB peak levels.
The amplifier started clipping the highest peaks already which added a sharp ‘edge’ at certain peaks.
I would not call those peaks anywhere near ‘pain levels’ though but ‘very loud’ none the less.

This resulted in the following (rounded off) numbers:
RMS levels = 1.35V = 5.6mW = 105dB (average)
Peak levels = 15VPP = 5.3VRMS = 88mW = 117dB peak
calculated DR = 11.9dB for that 10 sec part of the song.



I certainly do not recommend listening to these levels for longer than 1 minute or so.

---

This data shows that to drive the HD650’s to uncomfortable loud levels while still not nearing any clipping levels and having a few dB extra headroom you will need an amplifier that can supply at least 10VRMS which means the amplifier must be able to supply 300mW into 300Ω headphones.

To drive the HD650 to comfortably loud levels you only need around 1.7VRMS = 10mW into 300Ω though.
A source that is specified to reach 100mW in 32Ω thus will be able to do that job.



In other words... how much voltage (power) you need depends on how loud one wants to listen to occasionally without ever hitting distortion of the amp.
The thing about amplifiers is that peak voltages can consist of many different frequencies that by themselves are not very loud but all add in the signal.

 

[Chagall]

To drive the HD650 to comfortably loud levels you only need around 1.7VRMS = 10mW into 300Ω though.
A source that is specified to reach 100mW in 32Ω thus will be able to do that job.

Thanks for the thorough post, but there is one thing not addressed (especially with the HD series) i.e. EQ.
How does the calculation change if the user EQs their headphones with say -5dB to -7dB negative preamp?

 

[solderdude]

Thanks for the thorough post, but there is one thing not addressed (especially with the HD series) i.e. EQ.
How does the calculation change if the user EQs their headphones with say -5dB to -7dB negative preamp?

Well... when you add bass, for instance Amir's suggestion to comply to Harman, of about +10dB for the lowest frequencies and you turn the volume up to get the same loudness (compensate the negative pre-amp basically) you might need about 10dB more voltage (so triple the output voltage) when you have some really loud signals in the lowest frequencies but could also be a bit less than double the voltage in most cases.
3x the voltage (= 9x the power) for your quoted numbers means about 5Vrms (90mW in 300Ω) would be required for headroom to get to comfortable loud levels with thumping low bass.
IMO +5dB at 20Hz (and -4dB, low-Q around 150Hz) is all that is needed opposite the mids in which case 3V (30mW) would be sufficient.

 

[FTB]

Thanks both !

So it is not so power hungry. ~5 mW for 105 dB... ! A dongle with 10mW@300 ohms is enough.

 

[bequietjk]

Anyone have recommendation for quality built balanced cables for the HD6xx line? A brand/builder with a good track record and that uses decent materials?

 

[gvl]

Anyone have recommendation for quality built balanced cables for the HD6xx line? A brand/builder with a good track record and that uses decent materials?

If you need one with an XLR plug there are a couple of US-based sellers that sell the original Sennheiser cable with an XLR plug soldered on for around $40-50, they should work fine.