HD 280 Pro Sennheiser

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Kurt12

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Hello,

I just got myself a second hand HD 280 Pro Sennheiser (64 Ohms) for live monitoring because I had a limited budget.

I have seen a few articles about fake Sennheiser (but no articles about how to check if genuine or not). While upon inspection I can see that it seems genuine, I decided to check the impedance, I got 55-56 ohms per channel. Which seems alright since fake headphones seem to have about 20-30 ohms.

Would anyone know the best way to check if mine is fake or not ?
 
Hi Kurt. 55Ohms seems a bit low for 64 Ohm phones to me? Every set of cans I have ever measured has been within an Ohm or so of the stated impedance*. I suggest you blow the beer budget and buy a 68 Ohm 1W test resistor to check your meter!

Maybe someone here has some 280s and can do the honours?

*This is why I treat claims that headphone amplifiers must have a near zero output impedance as largely bllx!

Dave.
 
If there's another way to check, let me know. I have and use them.
 
Mine measure 88Ω, but it's possible they are out of spec.

HD280 used.webp
 
theres fake HD280s? wtf,,,whats next? fake DAW's and Fake Shure 57s?
fake Texas Instrument chips that are made in China but sold illegally by the same plant that builds all their other stuff?

I would bet money a lot of the fakes are built in the same factory just "off the books" so your probably ok even if they are "real fakes" or Rea-Real ones and not Fake Real ones...

and they are probably in better shape than boulders, maybe not as comfortable but cosemtically better shape.

I knew a guy measuring Fender Texas Specials and was getting different ohm readings all the time from set to set.
Isnt there some wierd reactance in the resistance testing of speakers? seems I recall the ohm isnt like a straight ohm its during a load...not be confused with blowing a load....but a load as in resistance and power and wattage.

so measuring it with a DVM isnt the way the pro's do it right?

Ive got a pair I can measure if I remember and will post. But now I dont know if mine are fake- real ones? damn..lifes getting confusing anymore.
 
Just checked. Why not? :)
My 64ohm hd280s measure 54 each side, and my 250ohm DT770s measure 240 and 256.

The 770s are two years old and the 280s are probably seven or eight.
 
Steenamaroo said:
Just checked. Why not? :)
My 64ohm hd280s measure 54 each side, and my 250ohm DT770s measure 240 and 256.

The 770s are two years old and the 280s are probably seven or eight.
Click to expand...

Yes S. The DTs are where I would expect headphones to measure. The HD280s are obviously a bit of an exception, I reckon OP is cool with his.

CoolCat: yes, speakers and cans have an AC 'impedance'* but at DC (what a DMM measures) this will have no effect. Speakers BTW all measure about the same ref rated Z. That an 8R unit will read about 6 Ohms DC and that holds for almost ANY size or brand. The exception is HD guitar speakers where DC resistance is often very close to nominal impedance.

*Properly called the 'modulus of impedance' and can only be properly shown by an R by F graph. Speaker and H/P Z is normally measured at 400Hz but don't bet on it!

http://www.wavecor.com/assets/images/SW263WA03-Impedance-curve.png


Dave.
 
HD 280 Pro- the symbol says 64ohm
I got 53ohm L and 53 ohm R - (106.5Ohm L-R)
Using a FLUKE 67...

the Beyer 250ohm measure 240ohm at idle/unplugged.
the Beyer spec sheet says.
Volts RMS required to reach 90dB SPL: 0.299 Vrms
Impedance @ 1kHz: 236 Ohms
Power Needed for 90d BSPL 0.38 mW
Broadband Isolation in dB (100Hz to 10kHz): -3 dBr

the HDpro per InnerFidelity
Volts RMS required to reach 90dB SPL: 0.061 Vrms
Impedance @ 1kHz: 65 Ohms
Power Needed for 90d BSPL 0.06 mW
Broadband Isolation in dB (100Hz to 10kHz): -16 dBr

so there might be some math class needed here, but I missed that day and was hanging out with John Doobie.
 
Last edited:
Happy to see Boulder's HD280s. Even though I sat on mine and broke them a couple of months ago, my gaffer taping is more tidy than his.

Anyhow, just measured the impedance on mine and got 59 ohms. Mine are about 8 years old.

Bob
 
Mine are at least 12 years old.

It's pretty normal for DC resistance to measure lower than the rated AC impedance. As already said, 8Ω speakers tend to measure at about 6.2Ω.
 
My 280s measure 55.4 and 56.0 DC ohms.

DT 770 Pros are 244. Both about 6-7 years old. Headband on the 280s split already. Kind of disappointing really.
 
bouldersoundguy said:
Mine are at least 12 years old.

It's pretty normal for DC resistance to measure lower than the rated AC impedance. As already said, 8Ω speakers tend to measure at about 6.2Ω.
Click to expand...

Exactly. DC resistance is not quite the same thing as AC resistance.
 
Bobbsy said:
Exactly. DC resistance is not quite the same thing as AC resistance.
Click to expand...

No, it is not Bobbs but the odd thing is, as I said, every set of cans I have ever measured come out close to or even a bit above nominal impedance.

Just checked two latest acquisitions. AKG K92* Nom' 32 Ohms. DC R=33 Ohms. JVC HA-SI65-B (cheap, £13, foldables from Sainsburys but remarkable nice sounding. Ideal for 'shows' in quantity where cans are likely to be trashed or nicked!) Nom' 32R but again DC=33 Ohms.

*Got these in June, Dads Day. Beautifully made but I was at first a teensy bit 'nah' with the sound? Bit dim to me (yes! I know! I AM mutton) but after a month or so I have come to realize that they are not 'dim' but smooth. Growed on me greatly! Fifty quid cans, now discounted to around £40 and they also get some good reviews. Top reccy from me for budget'ish closed backs.

Dave.
 
Hi & thanks to all,
[MENTION=19723]CoolCat[/MENTION] (theres fake HD280s? wtf,,,whats next? fake DAW's and Fake Shure 57s?)

I have seen other fake models like this one :
YouTube
though not the HD 280 Pro.

Also I was considering the Sony MDR-7506, plenty fake on the market like this one : 2017 MDR-7506 Professional Closed-Ear Back Large Dynamic Studio Audio Headphones | eBay

I read some articles about the Sony MDR-7506 to test the impedance where fake will show less than 30 ohms.

I have annexed a few pictures of my headphone here for people who have a similar pair on hand to compare.


20170831_093545.webp20170831_093530.webp20170831_093558.webp20170831_093614.webp20170831_093632.webp
 
Kurt12 said:
Hi & thanks to all,

[MENTION=19723]CoolCat[/MENTION] (theres fake HD280s? wtf,,,whats next? fake DAW's and Fake Shure 57s?)

I have seen other fake models like this one :
YouTube
though not the HD 280 Pro.

Also I was considering the Sony MDR-7506, plenty fake on the market like this one : 2017 MDR-7506 Professional Closed-Ear Back Large Dynamic Studio Audio Headphones | eBay

I read some articles about the Sony MDR-7506 to test the impedance where fake will show less than 30 ohms.

I have annexed a few pictures of my headphone here for people who have a similar pair on hand to compare.


View attachment 100302View attachment 100301View attachment 100303View attachment 100304View attachment 100305
Click to expand...

Yes, checking the DC resistance would seem to me to be a very good way to identify a fake. I would expect the fakers to use some cheap, 'generic' transducer since the average punter would never know or check.

N.B it would be a good idea to buy a 1% test resistor as close to the R of the phones under test. Two 33Rs would be handy and could be used to 'calibrate' the meter which could then be a ten quid 'Halfords' cheapy!

Dave. (e.g. Rolson 2759. More than adequate, prob' wasn't even a tenner!)
 
wow...its amazing they would have the ability to make fakes so perfectly and then toss in cheap speakers.

or...... as I said are they just stealing gear from the offshored foundry by production runs above the books and taking the extra boxes of stuff for the black market?

or...... what if they actual company is making a shit-line and sneaking in subpar pieces for the masses and giving the good stuff to the reviewers! this way they get good press and can then put cheap crap parts in the product to increase profit margins? they wont pay any taxes on the blacket market sales.

as they say on TV..."an inside job"??? hmmm....
 
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