Mr Spock
demokratischer - sektor
- Μηνύματα
- 18.457
- Reaction score
- 50.618
The output stage uses fixed bias obtained from a dedicated power supply. Bias adjustment pots and test points corresponding to each output tube are located in front of the output transformers. Luxman apparently did not intend these adjustments to be performed by anyone other than a qualified technician. Hence, no biasing instructions are included in the owner’s manual. However, seasoned audiophiles who are accustomed to biasing power tubes should have no problem with this. Although this amp does not require frequent bias checks, it is good practice to check and tweak the bias after the initial installation since the bias may vary with the local AC mains voltage, which in many localities runs higher than nominal. I would recommend a multimeter with long leads capable of measuring DC voltage below 1V. There are three test points for each channel, with the center point being ground, while the left and right test points are for the left and right KT88s. An insulated Phillips head screwdriver should be used to adjust the corresponding potentiometer as needed. And unless you have asbestos fingers, I would caution you to use a cotton glove to protect your hand from accidental contact with a hot tube. The test points allow you to measure the voltage drop by the idle current across a 10-ohm cathode resistor, a very common test scheme. The recommended voltage range for each test point is 0.46V to 0.48V, which implies an idle current of 46 to 48mA. In my listening room, the initial bias voltage checks conducted after an hour warmup were in the range of 0.50V to 0.53V. And after being tweaked to within the recommended range, the bias stayed rock-solid over a period of many weeks.
When it comes to purity of tone, it’s mainly about a benign distortion spectrum that is at play, one that does not emphasize odd-order harmonics. Triode amps have the edge in this regard, and as a consequence, the Luxman could never be characterized as a bright-sounding amp. Upper midrange glare was absent. That would be the sort of brightness that I typically associate with pentode designs, hence the moniker “pentode glare.” It tends to add false detail and drive to the music. And that’s not a good thing in my book, though some folks seem enamored with such a sonic “caffeine rush.”
Power output: 25Wpc (into 4, 8, and 16 ohms)
Input sensitivity: 890mV
Input impedance: 32k ohms
Frequency response: 20Hz–20kHz (+0, -0.5dB); 10Hz–100kHz (+0, -3.0 dB)
Total harmonic distortion: 0.1% (1kHz,1W); 0.5% (20Hz–20kHz,1W)
Signal-to-noise (IHF-A): 105dB
Vacuum tube complement: 2x ECC83S, 2x ECC82, 4x KT88
Dimensions: 440mm x 184mm x 230mm
Net weight: 16.1 kg
Luxman MQ-88uC Stereo Power Amplifier - The Absolute Sound
Luxman MQ-88uC Stereo Power Amplifier -
www.theabsolutesound.com
- τελικός με volume ουσιαστικά , ολιγόβαττος , αλλά με με καλές ( χαμηλές ) τιμές αρμονικής παραμόρφωσης , καλό ακόμα και στερεής κατάστασης Signal-to-noise . . . & όπως πάντα , κούκλος
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