The Stax Thread III
Oct 11, 2013 at 3:01 AM Post #542 of 25,540
   
With 6-10 volts average output voltage at the output of RKV (on a maximum 80 volts) for listening to an average level of 74-80 dB, and a load> 2 KOhms, there is no audible distortion. The degree of transparency and presence of sound is exceptional with 009 Stax headphones (without the 1:50 Wee transformers (bypassed)).
 
Otherwise, the RKV amplifier is used directly (without Wee transformator) to gain a high voltage (6-12 volts average ; maxi 80 Volts RMS), but with a very low power: maybe 40 mWatts to maximum output voltage of 80 volts RMS for a Stax 009 with an 145 KOhms impedance. (NB: the RKV can produce 3 Watts with a load of 200 Ohms)

 
 
Hello.
 
Potentiometer RKV 15 h (mean level "medium to high" loudly enough for me): 7.42 Volts (77.5 dB SPL)
 


 
 
Potentiometer RKV to 17 h (max) (mean level "strong" too hard for me): 12.72 Volts (83 dB SPL)
 


 

Potentiometer fully RKV (17 h) and with the Wee transformers bypassed, I just registered to a peak voltmeter level of at least 56 volts on a percussion (large drum) in a jazz recording of Henry Texier "Mad Nomads" that corresponds to a peak noise level of at least 96 dB SPL !
 
Otherwise, I always confirms the high degree of transparency and clarity of sound, and the realism and the strong presence of the vote.
Always zero audible breath.
 
Finally, the RKV amp has not given up the ghost and I do not see how it could do with a load of nominal output of 145 KOhms.
 
Eric
 
Oct 11, 2013 at 7:37 AM Post #543 of 25,540
Be careful.
 
To operate the combo RKV-Wee with enough gain (the transformators Wee shunted), it is imperative that the source (dac) has an output with an enough high level ; if it is not the case, the amplification gain of the RKV will be too weak to reach an average level expected of listening of 80 to 84 dB SPL (enough to use) and  a maximal (peak) modulation of 96 to 100 dB SPL.
 
Oct 14, 2013 at 3:13 PM Post #551 of 25,540
Oct 15, 2013 at 2:28 PM Post #552 of 25,540
As much as this test is informative; they had no 717  (OK, not so important as it's no longer made) ...but no BHSE...is not that amp based somewhat on the T2 with modernization and many upgraded components? (Alps, etc). Still the best sounding amp with 007 or 009 that I've heard and hence the benchmark for comparisons such as this.
 
Oct 16, 2013 at 11:10 AM Post #554 of 25,540
Hi, my 600 ltd is arrived and I am trying to biasing it. I can set the DC balance near to zero volts, but I can't set the DC offset: values are too high, near to -200V.
This is strange. i have measured also the DC offset value with the unit OFF and I have -70V. Someone can help?
 

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