Sennheiser HDVD800 Headphone Amplifier
May 18, 2013 at 1:50 PM Post #706 of 3,016
I thought this was fairly well established HF knowledge. One might even like the HD800s with a 100 ohms or more. Beyer tends to make amps with 120ohm output impedance for their products, it's no surprise that Senn chose a similar approach to power their 300+ ohm 800s. The HDVD800 is a shiny HD800 accessory that hobbyists have been demanding since '09. That demand might have cooled a bit since then but I don't doubt that the amp has a bright future.
 
Purrin's measurements with 170 ohm & 680 ohm resistors vs. near 0 ohm Cmoy:

 
May 18, 2013 at 2:11 PM Post #707 of 3,016
Quote:
Maybe a dumb question, is there a way to put a speaker system on the HDVD800 somewhere? Else, I'll have to stick to my V800 dac because that one has xlr outputs and rca outputs for both type of systems.
 
Anyone with a unit can tell?

I'm using the HDVD800 with my speakers. It has balanced outputs which are unaffected by the volume control, so you can't use it as a pre-amp like the V800, but you can use it as a dac. My amp only has unbalanced inputs, so I had to get a couple xlr to rca adapters to plug it in.
 
May 18, 2013 at 4:56 PM Post #708 of 3,016
Quote:
I'm using the HDVD800 with my speakers. It has balanced outputs which are unaffected by the volume control, so you can't use it as a pre-amp like the V800, but you can use it as a dac. My amp only has unbalanced inputs, so I had to get a couple xlr to rca adapters to plug it in.

Good to know, I am prolly gonna keep the v800 then and grab a HDVD600 or go for the HDVD800 after all
 
May 18, 2013 at 5:52 PM Post #709 of 3,016
Sennheiser head of tech departement said the HDVD800 was THE best amplifier made for the HD800, and that they know best how to amplify their own flagship headphone. I'm sure 0 ohm output impedance is NOT 43ohm.
Quote:
I thought this was fairly well established HF knowledge. One might even like the HD800s with a 100 ohms or more. Beyer tends to make amps with 120ohm output impedance for their products, it's no surprise that Senn chose a similar approach to power their 300+ ohm 800s. The HDVD800 is a shiny HD800 accessory that hobbyists have been demanding since '09. That demand might have cooled a bit since then but I don't doubt that the amp has a bright future.
 
Purrin's measurements with 170 ohm & 680 ohm resistors vs. near 0 ohm Cmoy:

 
May 18, 2013 at 6:04 PM Post #710 of 3,016
Grell is more the head of pushing Sennheiser products these days and he might not be inclined to claim just that, whether it has any basis in fact? 
 
Quote:
There is no modding of the gear needed.
There is a jack, 2 resistors & plug as a unit.
The jack goes into the amp just like the headphones do.
The headphones plug into the socket.
 
Amp > Unit with resistors installed > Headphones.
 
I could make one for you.

 
That is indeed it.  Figure out the output impedance of the amp used, build an adapter with resistors inline with the L and R channels and voila, you have an impedance adapter.  I'm using a souped up Dynalo (GS-1) which is close to 0ohm so I just added 42ohm resistors inline.  
 
May 18, 2013 at 7:27 PM Post #711 of 3,016
Quote:
There is no modding of the gear needed.
There is a jack, 2 resistors & plug as a unit.
The jack goes into the amp just like the headphones do.
The headphones plug into the socket.
 
Amp > Unit with resistors installed > Headphones.
 
I could make one for you.

2 questions please
 
1. am i right in saying that this can be like your own personal adjuster - upping and downing the ohms to achieve a sound that suits your headphones - in other words you could use a device like this to optimise any amp to suit anything from iem's to 600ohm headphones ?
 
2. you have a photo/diagram of one of these diy units ? - its something i would like to play around with 
 
May 19, 2013 at 2:06 AM Post #712 of 3,016
Quote:
Sennheiser head of tech departement said the HDVD800 was THE best amplifier made for the HD800, and that they know best how to amplify their own flagship headphone. I'm sure 0 ohm output impedance is NOT 43ohm.

Unfortunately it's not that simple to say it's the best. It's easy to say these things, but don't forget, there's marketing behind this. I can say it's among the best amps in keeping the HD800's linear, but again not the best.
 
Audio-Technica Stay updated on Audio-Technica at their sponsor profile on Head-Fi.
 
https://www.audio-technica.com/
May 19, 2013 at 5:38 AM Post #713 of 3,016
Quote:
[...] Quote:
There is no modding of the gear needed.
There is a jack, 2 resistors & plug as a unit.
The jack goes into the amp just like the headphones do.
The headphones plug into the socket.
 
Amp > Unit with resistors installed > Headphones.
 
I could make one for you.

 
That is indeed it.  Figure out the output impedance of the amp used, build an adapter with resistors inline with the L and R channels and voila, you have an impedance adapter.  I'm using a souped up Dynalo (GS-1) which is close to 0ohm so I just added 42ohm resistors inline.  

 
Outing my lack of knowledge:
 
If you use a normal, single ended TRS connection: Will one resistor on the return/ground leader do the same job, or do I miss something?
 
Thank you in advance for your help and clarification.
 
@hedphonz:
1. Yes. I even assume you can use (a) good quality potentiometer(s) or stepped attenuator(s).
 
2. wink's description probably is enough (except for my single ended question which deals with a possible simplification).
 
May 19, 2013 at 6:28 AM Post #714 of 3,016
No, the resistance is in series with the output of the amp.  So when you'd make an adapter you'd solder two resistors to the tip and ring of the of the TRS plug and then the signal wire that goes to the socket at the other end goes to the other ends of the resistors.  The ground is just passed through as it is. 
 
May 19, 2013 at 6:49 AM Post #715 of 3,016
Quote:

CDWMcInSpots

If you use a normal, single ended TRS connection: Will one resistor on the return/ground leader do the same job, or do I miss something?

Yep, that works too. although it is better form to keep the circuits separate to the return connection in the amp..
With the resistor in the return leg it puts the circuits above the return connection at the amp and may cause problems.
For the cost of a resistor it's best to be safe.
 
Also. having 2 circuits sharing the same resistor effectively doubles it's effective resistance in each circuit.
 
___300Ω________
                         I
                         I_______43Ω_____  is equal to:
___300Ω_________I
 
___300Ω________________86Ω_______
                                                     I
                                                     I_____
___300Ω________________86Ω_______I
 
May 19, 2013 at 7:15 AM Post #716 of 3,016
@wink:
 
Thank you for your answer.
 
@spritzer:
 
Either you misunderstood my question, or I misunderstand your answer, but thank you for your effort trying.
 
May 19, 2013 at 11:03 AM Post #717 of 3,016
Quote:
Sennheiser head of tech departement said the HDVD800 was THE best amplifier made for the HD800, and that they know best how to amplify their own flagship headphone. I'm sure 0 ohm output impedance is NOT 43ohm.

Yeah, Germans can get a little prissy and authoritarian like that.
 
Luckily they're also good engineers and not daft enough to think that electrical damping is some sort of esoteric knowledge they hold a monopoly on.
 
May 20, 2013 at 10:16 PM Post #719 of 3,016
I've noticed that the USB input creates high frequency noise from my speakers. This doesn't happen with any of the other inputs, and I have a USB-AES converter (Musical Fidelity V-LINK 192) which I'm using instead right now. The noise isn't audible over the headphones, even if you max out the volume, so it only affects speakers. I assume this is computer noise somehow transferring over, because the noise is affected by what happens on screen, so if I open and close programs the noise is affected. So whatever their USB solution is it could be better.
 
May 20, 2013 at 10:29 PM Post #720 of 3,016
Quote:
I've noticed that the USB input creates high frequency noise from my speakers. This doesn't happen with any of the other inputs, and I have a USB-AES converter (Musical Fidelity V-LINK 192) which I'm using instead right now. The noise isn't audible over the headphones, even if you max out the volume, so it only affects speakers. I assume this is computer noise somehow transferring over, because the noise is affected by what happens on screen, so if I open and close programs the noise is affected. So whatever their USB solution is it could be better.

Most likely USB Receiver is not galvanically isolated, uses USB power, or you are just dealing with good ole ground loop.
Something like iUSB Power may help.
 

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