- Frequency Response: 20Hz-20Khz, -0.1db, 7Hz-200KHz, -3dB
Maximum Power, 50 ohms: 180mW RMS per channel
Maximum Power, 300 ohms: 800mW RMS per channel
Maximum Power, 600 ohms: 450mW RMS per channel
THD: < 0.02%, 20Hz-20KHz, at 1V RMS, high gain (worst case)
IMD: < 0.03%, CCIF at 1V RMS, high gain (worst case)
SNR: > 98db, unweighted, referenced to 1V RMS, low gain
Crosstalk: < -71dB, 20 Hz-20KHz
Output Impedance: 14 ohms (hi gain), 3.5 ohms (lo gain)
Gain: 7 (16.9db) or 1.5 (3.5 db), via rear switch
Topology: All-triode, noninverting, single voltage gain stage, current source biased front end and optimized WCF output stage, DC-coupled input
Tube Complement: 6N1P dual triode input, 6N6P dual triode output, 1 each per channel. 6N1Ps rollable to 6DJ8, E88CC, 6922, 6BZ7, and similar types.
Power Supply: Two internal power transformers with over 2,000uF of filter capacitance
da un OTL (la prima versione era dichiarata no global feedback, ora nel Valhalla 2 sembra sia apparso) con una 6N6p ?
Stando a:
( http://www.diytube.com/phpBB2/viewtopic.php?p=36891 )
chi lo ha guardato "sotto la gonna" ha trovato un differenziale di 6N1 (ECC88-like) con generatore di corrente, seguito da un White Cathode Follower di 6N6p (5687-like)
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Postby EWBrown » Tue Mar 29, 2011 10:04 pm
After a few hours of operation, I decided that it was time for a real look under the covers
A procedure which is much easier said than done, as there are lots of 4-40 screws to remove, and some of those took a bit of patience and perseverance to remove. Just think of those vexingly complicated 1950's and 1960's vintage wooden "Chinese" puzzles which were fairly challenging to take apart, and then put back together again. First of all, I should have known that it has no SRPP circuitry at all, it is clearly stated that this is a non-inverting circuit, and SRPPs invert.
The topology is a common cathode 6N1P VA stage (not to be confused with grounded cathode), and a 6N6P White cathode follower. For those who have Tube-CAD, the VA is hum-bucking common cathode "D" , directly coupled to a White CF "A"
Each VA stage consumes about 8 mA, and each WCF output stage consumes about 28 mA, for a total of about 76 mA for both channels, at 212VDC.
The power supply uses two separate MCI brand PC mounted transformers (made in California) , one for the 212 VDC B+, the other for the filaments' 6.3VAC.
Most resistors are Dale, 1% 1/2 watt, some 1 watters are used where needed. The power supply has a total of nearly 2,000 uF of capacitors, and this unit is dead quiet, no hum, ripple, buzz or noise. The volume control is 100K stereo Alps "Blue Velvet" Caps are a mix of Nichicon electrolytics and Wima MKS4.
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, date le tensioni e correnti in gioco, ma forse non molto distanti.
........il prototipo è in funzione da tempo. (il tavolaccio fà un pò schifo) 
del loro trabiccolo!