[ruthieandjohn]

Do you mean amplifier output power at different load impedances? Or amp output impedance dependance on amp output power? Or something else even..

Sorry not to be clear...

Amp output power vs. headphone input impedance.

 

[Priidik]

Sorry not to be clear...

Amp output power vs. headphone input impedance.

For HDVA600 output power is determined by voltage that reaches hp-s voice coil, as its current capabilities should be sufficent down to 10ohms by the chip amp (pair inside the Senn amp) datasheet, by which it should supply 1.4A of current in bal mode. 
Voltage applied on voice coil is result of voltage divided by amp output impedance and voice coil impedance. Output voltage peak is 24V or 17V rms, so power can be calculated. 

 

[jagwap]

  Thanks! I've waited long for clarification on this.
Can we by any chance have pictures? So there are nothing more under the heatsink?
I wonder why they added 33ohms to single ended, unlikely for stability reasons alone.

I think it was to match the 40 ohms on the balanced: 33 +10 = 43, (10+10) x 2 = 40 
 
But if you mean why so much, remember the 33ohms is to each unbalanced socket, so isolating each one a little, and also the 0.5dB boost in the bass may have been an optimisation for the HD-800.
 
I am going to try taking the extra resistance out of each of the left hand outputs, while leaving the 10 ohms near the amp in, to lower the output impedance and see if it improves the amp for other headphones.

 

[SilverEars]

Sorry not to be clear...

Amp output power vs. headphone input impedance.

Hi, John.  I know you asked about the HE-6, and here is some useful info comparing the 800 to HE-6.  Huge difference as you can see.  Also, the output impedance of the 800 amp is too significant compared to HE-6's impedance, so power transfer will be much less on top of HE-6 requiring gobs of voltage and current compared to the 800.  GSX has better power transfer capability with 0 output impedance.  Any output impedance will limit power transfer to the load, the headphones.
 
This link has list of most headphone and their current, voltage, power, and gain needs.  It's pretty useful reference.
http://www.head-fi.org/t/668238/headphones-sensitivity-impedance-required-v-i-p-amplifier-gain
 

Manufacturer	Model	S@1V [dB SPL]	Z [Ω]	Voltage [V]	Current [mA]	Power [mW]	Gain [dB]	Notes
Hifiman	HE-6	89	43	11.22	260.935	2927.734	15
Sennheiser	HD800	103	430	2.239	5.206	11.656	1

 

[akhyar]

^ isn't the IE800 iem?

 

[SilverEars]

  ^ isn't the IE800 iem?

Yes.  It's fixed now.  

 

[ruthieandjohn]

Here's what I'm trying to find out...
 
I am the proud owner of a new Sennheiser HDVD800 DAC and amp.  The amp drives the Sennheiser HD 800 headphone beautifully. 
 
But since I find that 1/2 the people that have both the HD 800 and the HiFiMAN HE-6 rate the HE-6 above the Sennheiser 800, and since the HE-6 takes a very capable amplifier, I am trying to figure out if my HDVD800 will also do justice to the HE-6.
 
My suspicion, based solely on the volume of their respective boxes, is that the HDVD800 is inadequate for the HE-6.  The size of the HDVD800 box is about 1/5 the size of the EF-6, which is the HiFiMAN amp that they build for the HE-6 headphone.
 
I only have two rather wispy fragments of data:
 

1. HDVD 800 can drive a 600 ohm load at 480 mW (not sure where I got this factoid);
2. HE-6 headphone wants 5W (or 5,000 mW) of power, and has a 50 ohm input impedance (not sure at what frequency).(I haven't yet looked at the link or absorbed the table that SilverEars kindly posted to see if this is true).

 
Many amplifiers (e.g., Woo Audio) give their output power into a variety of load impedances...
 
Here is a page from the user manual for the Woo Audio WA6-SE as an example:
 


This would suggest that *if* the HiFiMAN HE-6 really did require 5,000 mW into its 50 ohms of impedance, the WA6-SE would be inadequate, as it only seems to provide something between 1,900 mW (at 60 ohms) and 2,000 mW (at 32 ohms).
 
Make sense?
 
I'd like a table like the one for the Woo Audio WA6-SE, shown above, for the Sennheiser HDVD 800. 
 
(Of course I could ask Sennheiser, but this is so much more engaging.  Besides, I asked another amp supplier for theirs and merely got a statement that "our amp works great for any headphones up to 600 ohms." No table).
 
I bet if I take the efficiency (SPL at 1V per SilverEars' table), figure out what SPL is needed for robust listening, figure out the volts, include the impedance, then compute an associated power, I will have a way of figuring out whether 5,000 mW is really the right number for the HiFiMAN HE-6.  Right?
 
But I still don't know what the HDVD 800 puts out at the HE-6 impedance, and near as I can tell, output power at one impedance is not derivable from output impedance at another impedance.

 

[SilverEars]

That's output power into a resistor.  Also, part of that power could be dropped to the source impedance.  Also, that is proabably max power, and could be beyond 1% distortion level.  You want to know output power below 1% distortion level.  You have to take loudness into account.  The link I posted are requirements for 110dB SPL for headphones.  

 

[Priidik]

 
But I still don't know what the HDVD 800 puts out at the HE-6 impedance, and near as I can tell, output power at one impedance is not derivable from output impedance at another impedance.

 
I responded to this very question in post 2201. Its about 1.4W,
but it won't matter, because there isn't enough damping provided by the HDVA. If you have output voltage of the amp and you know both impedances and current supply won't run out then you can calculate the power. Voltage squared divided by impedance is power.
Only source of uncertainity is the amp output impedance swing, if there is one.

 

[biopsyh66]

Hello!
 
Can anyone suggest whether to Sennheiser HDVD 800 headphones Fostex TH600, or not?
I'm afraid that due to low resistance and high sensitivity of the headphones they will not work together very well.
Thanks in advance.

 

[James-uk]

Hello!

Can anyone suggest whether to Sennheiser HDVD 800 headphones Fostex TH600, or not?

I'm afraid that due to low resistance and high sensitivity of the headphones they will not work together very well.

Thanks in advance.

The HDVD800 is best suited for high impedance headphones. I would look for an amp with a near zero output impedance if I were you.

 

[obsidyen]

  Hello!
 
Can anyone suggest whether to Sennheiser HDVD 800 headphones Fostex TH600, or not?
I'm afraid that due to low resistance and high sensitivity of the headphones they will not work together very well.
Thanks in advance.

They probably won't work very well. I recommend Chord Hugo. Output impedance is 0.075 ohms. It can drive my 300 ohms HD650s with authority as well. The thing with Fostex headphones is even though they are low impedance, they require high quality source/amp to sound their best. Hugo ticks all the boxes for them.

 

[SilverEars]

Yeah, 800 is a useless amp unless the load is high impedance.  Schiit Mjolnir  seems like a much more flexible amp that should react well with pretty much all loads as it can output 5W with 1.5ohms output impedance. Yes, that includes the HE-6. Speaker amps are nice for planars, but nothing else.

 

[Priidik]

 

I would argue. AKG K701 benefits from a Marantz that i have.

 

[SilverEars]

  I would argue. AKG K701 benefits from a Marantz that i have.

Oh yeah?  How do you think it benefits from the Marantz?  K701 and HD800 had very similar results based on Tyll's measurements.