[justin w.]

Batch #4 parts just arrived

 

[bearFNF]

Batch #4 parts just arrived
 

Sweet!!!  Hopefully no fakes in there...

 

[lojay]

i will be sending an email about that soon

Thanks Justin!

 

[rob360]

So Justin, is the next production run (batch #4) sold out???

 

[caseyse]

Can someone shed some light on the ALPS RK50 used in the BHSE?  
 
Does the RK50 use a ladder of SMD resisters vs. a conventional pot that drags contacts across a wire/membrane surface?  If the RK50 uses a resister ladder, is the adjustment perceived to be fully linear?  I can't tell from the specs on ALPS' Web site.
 
Thanks 

 

[icebear]

... not a part specialist here but from what I can read in the specs, this looks like a traditional potentiometer
i.e. NOT a stepped attenuator with single resistors :
 
http://www.alps.com/prod/info/E/HTML/Potentiometer/RotaryPotentiometers/RK501/RK50112A0004.html
 
-Part number RK50112A0004
 
-Number of resistor elements Dual-unit
-Gang error -100dB to 0dB 3dB max.

 

[purk]

  Can someone shed some light on the ALPS RK50 used in the BHSE?  
 
Does the RK50 use a ladder of SMD resisters vs. a conventional pot that drags contacts across a wire/membrane surface?  If the RK50 uses a resister ladder, is the adjustment perceived to be fully linear?  I can't tell from the specs on ALPS' Web site.
 
Than

It is a traditional pot built to the highest tolerance.  I have it on my BHSE & DIY T2 and I'm extremely happy with it.  However, If you already own a DAC with an excellent digital volume attenuation, then the DAC-T should be select over the RK50 for economic reason without any expense of performance.  What the RK50 is great for is an infinite adjustment of volume/step, while you are limited to 24 volume positions on the DAC-T.  

 

[eric65]

Hello Kevin,
 
What is the output impedance of the BHSE (and also, to compare, that of the SRM 727) ?
 
For information, the internal resistance (output impedance) of the RKV-II would be of the order of 0.05 Ohm: 200 Ohm (load) / 3600 (damping factor at 200 Ohm)
 
See the link (RKV-II and Verto): specifications :
http://www.audiovalve.info/rkv/audiovalve%20rkv%20mark2.php  
and  http://www.audiovalve.info/to/verto.php 
 
and the commentary of the constructor:
 
" For a game changing product a simple idea is not enough, you have to find also a proper implementation. There are already promising approaches in the market combining transformers with headphone amps to drive STAX headphones. But RKV and VERTO are now exploiting the full potential of that approach. Inductance and capacitance of the transformer can harm the sound. The Pikatron output transformers we use have only very little stray inductances and capacitances. To avoid distortion we use only a low step up ratio of 1 to 5. But key is the fact that the output impedances of RKV II and III are extremely low, too low to cause any negative effect on the sound."
 
Eric

 

[arnaud]

 
What is the output impedance of the BHSE (and also, to compare, that of the SRM 727) ?
 
Eric

 
Not insulting, but not far either...

 

[Ali-Pacha]

Eric, I think all the answers you need are right here : http://headwize.com/?page_id=751
 
Ali

 

[kevin gilmore]

  Hello Kevin,
 
What is the output impedance of the BHSE (and also, to compare, that of the SRM 727) ?
 
For information, the internal resistance (output impedance) of the RKV-II would be of the order of 0.05 Ohm: 200 Ohm (load) / 3600 (damping factor at 200 Ohm)
 

WOW, we are up to .05 ohms. Also a complete fabrication.
http://www.krellonline.com/downloads/Evolution_Brochure.pdf
so you are telling me that the rkv-ii has the same impedance as a krell 402.
Really, is that so. Not even for the first microwatt. What mighty tubes
a pair of pcl805 must be. way stronger than 6c33.
 
The output impedance of the BHSE is 5.1k ohms on each side. For safety purposes
so that the diaphrams don't get destroyed. Same as srm313,srm323,srm717,srm727,
sr006t,sr007t,srm-t1,srm-t2 etc. If the Verto does not have these safety
resistors, it will definitely damage the headphones.
 
The 2 minute or more charge time on the verto is also real bad. That means that
the headphones don't have any bias for 2 minutes while the music is playing.
Very bad for the charge layer on the diaphragm. Koss learned this 40 years ago
with the esp6.

 

[eric65]

  WOW, we are up to .05 ohms. Also a complete fabrication.
http://www.krellonline.com/downloads/Evolution_Brochure.pdf
so you are telling me that the rkv-ii has the same impedance as a krell 402.
Really, is that so. Not even for the first microwatt. What mighty tubes
a pair of pcl805 must be. way stronger than 6c33.
 
The output impedance of the BHSE is 5.1k ohms on each side. For safety purposes
so that the diaphrams don't get destroyed. Same as srm313,srm323,srm717,srm727,
sr006t,sr007t,srm-t1,srm-t2 etc. If the Verto does not have these safety
resistors, it will definitely damage the headphones.
 
The 2 minute or more charge time on the verto is also real bad. That means that
the headphones don't have any bias for 2 minutes while the music is playing.
Very bad for the charge layer on the diaphragm. Koss learned this 40 years ago
with the esp6.

 
Just wait 2 minutes, the potentiometer of the RKV to zero, before listening to music. 
Really, I do not see where is the problem.
 
You have still not answer me concerning the internal resistance of the BHSE and SRM 727, without the resistance of security.

 

[kevin gilmore]

   
Just wait 2 minutes, the potentiometer of the RKV to zero, before listening to music. 
Really, I do not see where is the problem.
 
 

If there is no music, then there is no AC voltage required to build the bias voltage.

 

[Ali-Pacha]

I don't have a clue in electronics but I can't see how to get bias without input signal. Audiovalve's page : "

To establish the

 

charge

 

an adequate

 

volume

 

is required."

Maybe a timer which blocks output signal except bias. No evidence of such a device on the page.

I also don't understand how this box does manage the bias value. Could the circuitry be fast enough to detect central pin and switch from 580 to 230 without any risk of arcing ?
Wrong thread anyway.

Ali

 

[eric65]

  If there is no music, then there is no AC voltage required to build the bias voltage.

 
And well just send a weak signal (eg 1 volt) (potentiometer of the RKV early in the race (in no case at max)); This seems fairly intuitive.