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(I've also posted this over in the Propeller Head Forum - apologies for the duplication)
Not sure if here is the correct venue, but here goes:
I own a Luxman SQ-N100 tube integrated that I purchased to anchor my office system. Rumor has it that it is also an exceptional headphone amp. In order to make some informed headphone choices, I'm trying to understand what the power output would be for headphones of different ohm ratings.
Given the info I've included below, is it possible to calculate headphone power output? ...say for 20, 36, 46, 62, 80, 100, 300 and 600 ohms? I realize that sensitivity comes into play, too, but those ratings are usually available in published specs.
If there is general formula I can apply, I'm happy to do the math. Thanks!
This is a quote from the review whose link I have included if you are interested - it describes the headphone circuit:
"Headfi fanciers will be excited to learn that their ¼" socket taps directly into the SQ-N100's main valve output stage. For ear speaker purposes, the output voltage simply couples through a pair of 470-ohm load resistors to attenuate its strength."
These are the Luxman specs:
Rated output: 12W + 12W (6Ω), 10W + 10W (8Ω, 4Ω)
Input sensitivity: LINE: 150mV, PHONO (MM): 2.2mV
Input impedance 47KΩ
Frequency response 20Hz - 50KHz (within -3 dB)
Total harmonic distortion 0.3% or less (1 kHz rated output)
S/N ratio 90dB or more
Input LINE: 3, PHONO (MM): 1
Output SPEAKERS: 1
Functions Remote control applied (sound volume), head phone output
Tone control (bypass enabled), AC inlet
AC outlet X 2 (non-interactive, total 200W max.)
Circuiting system Mullard type UL connections
Vacuum tubes used ECC83 X 1, ECC82 X 2, EL84 X 4
Power consumption 95 W (Electrical Appliance and Material Safety Law),
71 W (no signal)
Power supply AC 100V (50/60Hz)
Accessories Remote controller, power cable
Dimensions 297W X 162H X 210 (258) D mm
(I/O terminals in brackets, including operating knobs)
In order to keep things simple, let's assume there are only four electrical parameters. They are voltage, current, resistance and power. They are related to each other by equations known as Ohm's Law. The following three equations are used for calculating power:
Power = Voltage x Current
Power = Current 2 x Resistance
Power = Voltage 2 / Resistance
Therefore, in addition to knowing the resistance of the headphones in ohms, you also need to know either the current flowing through the headphones or the voltage applied to the headphones in order to calculate power.
For example, if you have 600-ohm headphones and your headphone amplifier applies 2-volts to the headphones, power would be calculated as follows:
Power = 2 2 / 600 = 4 / 600 = 0.00667-watts = 6.67-miliwatts
Another example: Suppose you had 32-ohm headphones with 1-volt applied.
Power = 1 2 / 32 = 1 / 32 = 0.0313-watts = 31.3-miliwatts
I hope this helps.
John, thanks for this - appreciated! The calculator is helpful, too.
If I'm reading your info correctly, it doesn't seem that I have enough information on the Luxman to calculate what the power output would be at any given resistance (headphone ohm rating) - am I correct??? Apologies if I'm missing something - this stuff is Greek to me.
BTW...I'm sure you don't remember, but we met years ago at one of MuzikMike's Ribfests - I had a blast; miss him.
No, there's not enough information given on the Luxman to calculate power at the headphone output, but most components with headphone jacks have enough power to drive just about any headphone. Therefore, I wouldn't worry about it.
What headphone are you planning to use? I own three headphones. I bought the original Grado HP1 headphones back in 1991 and they still work just fine. I bought Grado RS-2 headphones in 2003. Then, just a couple of months ago I bought some Koss electrostatic headphones and they sound awesome.
Yeah, Muzikmike's Ribfests were a lot of fun. I miss him, too.
Ok...so, at least on the surface, I understand what it takes to use the calculator you supplied. Thanks.
I own a pair of Shure SRH-1540 headphones that don't really need a lot of power to make decent sound...with the Luxman however, they are much more full-bodied and articulate.
I attended a CanJam Conference this past March (NYC) and came away interested in the Audeze LCD-X, LCD-XC, LCD-3, and the Focal Elear. I've since become curious about the Sony MDR-Z1R. My budget will be up to ~$1500 new or used.
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