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The HDV 820 manual shows INPUT Impedance 20 K ohms, OUTPUT Impedance 270 ohms.
yes but I'd rather not tear at my screen cover
as it is removable via those little screws
I need a improved cable as well, so I may just hang onto to the SDR inserts until after I upgrade the cable. As another member suggested, I'd like to get to know the stock sound first before I start to tinker, and finding a cable will be fun... Though I might honestly just have a HD800 to Audeze Mini 4 adpater built, so I can use some of my existing cables with the HD 800 if that's possible
That is the output impedance for the dual 3-pin preamp line out for active monitors. Damping factor really isn't very important for an IC out... that's there to kill any noise from the amp.
@ruthieandjohn - As far as the headphone outputs go, it states "minimum 16 ohms" for all headphones in the manual, which leads me to believe it is probably < 2ohms, but @Sennheiser could probably get us a real answer from the engineers.
If it states MINIMUM 16 ohms, doesn’t that sound like “no lower than 16 ohms...” or 16 ohms and up? Not necessarily a problem for high impedance headphones, like the HD800, many Beyerdynamics, Sony’s, and AKGs,.. just questionable for the ones I mentioned above.
Sony has the same challenge... the output impedance of their PHA series of portable DAC/amps is 10 ohms. They USED to include this on the data sheet of for example the PHA-1, but about a year and a half ago, it was removed. Works great for higher impedance Sony headphones, but I think they consider it a sore point, hence the removal of output impedance from the Sony PHA data sheets. You can, however, still look up the output impedance of the output opamp from its manufacturer data sheet and find it is...10 ohms.
On the HDVD800, and I think on the HDV820, they used panels of listeners using the HD800, not slide rules and calculators to compute impedance, while they varied the output impedance, arriving at a listener-based preference for 43 ohms.
I found your answer... it is, in fact, 40 ohms. This may be problematic with your Grado collection. It didn't sound bad w/ 25 ohm Denons, though you really want to get something under 3 ohms with those/Fostex, generally speaking. 40 ohms is certainly not optimal.
It won't matter too much with the planars, as the 8:1 damping factor isn't such a big deal when a headphone has a relatively flat impedance. Coil-wound dynamic drivers can have large peaks in inductance, which can make damping an issue if there is too much resistance from the amplifier.
I bet that, as great as the HD800 with the HDVD800 sounds, the HD800S with the HDV820 must be SUBLIME! Thanks for researching the impedance!
On the HDV820, design chief Axel Grell confirms that the output impedance was chosen with listening test for a variety of headphones, as indicated by the quote from one of the Sennheiser posts in the HDV 820 Q & A thread here in head-fi, pasted below.
“"I know it's designed with full-sized headphones in mind, but how does it perform with IEM's (Sennheiser IE 800 in particular)?... I've read as a general rule of thumb that you want the output impedance of your amp to be at least 1/8th that of your headphone's impedance. Even some full size headphones like the Fostex TH900 (25 Ω) and Focal Utopia (80 Ω) could be negatively affected."
[Grell, Axel] There is no general rule for “the right output impedance” for a headphone amplifier. There are some high output impedance tube amplifiers that sound great, others don’t, some Zero- Ohms solid state amplifiers sound cold and harsh, others sound good. A headphone and a headphone amplifier is a complex system of impedances, amplifier feedback loops, amplifier current supply and so on. That could lead to typical distortions and dynamic changes of the amplifiers output parameters depending on the headphone impedance and the type of amplifier. Therefore we made listening tests with many different headphones (Sennheiser and other brands from 25 Ohms up to 600 Ohms) using different impedances at the output of the prototypes of HDV 820. The outcome of this listening tests are the output impedances of the HDV 820.
As you can see from the attached curves a HDV 820 can drive a TH900 with 2.75 W. This should be enough.”
Once upon a time, the "standard output impedance" was 120 Ω. Generally speaking, don't lose sight of the forest because of focusing too much on one tree.
And if you want to modify it don’t forget the anax mod too. As seen here and on innerfidelity
Honestly if the SDR isn't enough I'll likely send it out to a friend to have him mod it... I've heard another HD 800 he modded and it was GLORIOUS, absolutely beautiful! Really it was the memory of that modded HD 800 that prompted to get my own! I enjoy appreciate the work of others more than my own honestly, his mods are very unique to his own personal preferences and I enjoy... getting to enjoy music with some of his preference and personality introduced into the mix,
I like the Eikon/LCD 2.2 for that as well, for their unique take on a simmilar sound signature. Really the only headphone I own that's MINE is my HE 4! I don't need or want another headphone that's been modded to my preference, that's kinda boring really. Though, the stock HD 800 is really the embodiment of what Sennheiser thinks "neutral/natural" is and part of me kinda wants to experience their vision before I meld it with some one else's.
If I REALLY LOVE it stock, I may just to a cable upgrade and save up for another used pair to have modded!
So I just finished up my first listen of the stock HD 800! I only had my HM601 and my APPJ PA 1502A headphone amp with me, and while the PA 1502A is a nice little SET Amp, mine is a work in progress so it's got some functionality flaws...
Non the less, I had a few co-workers on hand to try them too and every one enjoyed them! I personally, didn't feel they were too bright OR to thin. I Actually enjoy the balance of mids/highs, my only complaint was a lack of resolve in the sub bass... but that is more a fault of my Dac/Amp chain than the HD 800. Once I get them home and listen with my reference system I don't think I'll have that issue any more. I do really like the overall balance of them in stock form!
I've got to say, I'm at home listening out of my desktop system and... I can finally see why there's so much love for these! The Dynamics are amazing, the resolve is phenomenal and the imaging is amazing! Don't understand why/how people feel that some tracks or songs sound "distant" I guess I'm just not as big a fan of intimacy!
The h800 definitely has a wow factor when you first hear them.
IMHO they ate of exceptional value. But i also understand why some people might not take to them
Well honestly the really did NOT wow me till I got them into my desktop system. My Hm901/PicoPower does phenomenally well with a lot of what I own! But it just wasn't all that great with the HD 800, the frequency response is exactly what I've always heard it is and frankly in terms of resolve/tactility it does trade blows with my LCD 2.2, and finally the sound stage is really dependent on the track. I'm listening to Dance of the Zephyrtimes, very GRAND classical piece and... I'm not really hearing or experiencing anything new... it's technically a smidge airier than the LCD 2.2 or my HE 4 but... I dunno it's not WOWING me like every one says the HD 800 does with classical
Either way, the sound signature is not for every one. And plenty of people really do love that warmer intimate sound. For better or worse I started down the Audiophile rabbit hole with a DT 880 so I always knew I'd wind up with an HD 800, it's a sound signiture I've always enjoyed. Though honestly, I'm happy I waited as long as I did... I think had I gotten it years ago, before I made all the little final tweaks to my system, it would have just disappointed me like the first 2014 Fazor'd LCD 2.2 I heard...
I dont think you require any tools. Its just peeling off the mesh fabric and inserting the felt pads. All the best.