OK 6 months on the amp + counting
Ok 1st off I want to say I have had this amp for a while now about 6 months, with all upgraded tubes, totally love it!
I also upgraded that power cable with a WW cable from Ivan, and have a dedicated power conditioner too.
I have a question, I have a pair of Sennheiser HD700s and was wondering which is best to use for the connection.
High impedance headphone output or the Low impedance headphone output?
I did read this:
"The output impedance is measured to around 15 ohm for the low headphone output, and the high headphone output right around 48 ohm. If you believe in NWAvGuy’s theory(?), your headphones should have at least 8 times higher impedance than the output to avoid distortion of the audio signal. "
The 700s are rated at a 150 ohm load. I think I have always used the LOW connection. This amp has enough power to drive 2 pairs of I think about anything at the same time. Only diff I hear is on the low connection the loudness is maybe a little lower 5-10% or so perceived. Noise floors seem the same.
I sent a request to Woo to get their reply, but thought someone could chime in with some input too.
thanks!
HD700 specs.
Frequency response 10-42,000 Hz
Ear coupling Around-the-ear
Transducer principle Dynamic, open-aire
Nominal Impedance 150Ωs
Sound Pressure Level 105 dB (1 kHz, 1 V)
Total Harmonic Distortion <0.03 %
Jack plug ¼ inch (6.3mm) straight
WA6SE specs for a stock amp ( Mine has the best in class tube +cable upgrades)
- Technical Specifications :
- Headphones impedance : 8-600 Ohms
- Input impedance: 100 Kilo-Ohms
- Frequency response: 15 Hz - 40 KHz, -3dB
- Power output > 1 watt
- Signal/Noise: 93 dB
- THD: <= 0.3%
- Voltage: AC 110/220 V, 50/60 Hz
- External dimension (each unit): 6"(H), 5½(W), 13"(D)
- Weight: AMP 12 lbs, PSU 10 lbs
- Standard Features:
- Point-to-Point wiring
- One 5AR4 [PDF] rectifier tube. Direct substitute: 5U4G
- Two 6DE7 / 6EW7 [PDF] drive/power tubes
- Pseudo-dual power supply
- All tubes. No semi-conductors in the entire circuitry
- High and low impedance headphones outputs
- 1/4" (6.3mm) headphone jack
- 2 RCA inputs with a input source switch
- Individual filter choke per channel
- 80 watts specially made toroidal power transformer.
- Full aluminum die-cast chassis, anodized finish
- Whole aluminum volume knob and power switch button
- Gold-plate RCA
- Alps potentiometer and power switch
- Silver-plated hook-up wires in Telfon jacket
- Brief Introduction to 6DE7/6EW7:
- 6DE7/6EW7 is a dual triode tube, consisting of one drive triode and one power triode. Its performance is similar to a combination of a 6SN7 and a 2A3.
Rectifier tube upgrade:
Sophia Princess Mesh Plate 274B rectifier
Drive/Power tube option 1:
1 matched pair of 6GL7/6EM7 plus one pair of 6GL7->6DE7 Teflon tube adapters. $150 (2 tubes + 2 adapters)
The 6GL7/6EM7 is the ultimate driver/power tube for the WA6-SE. It has great extension and excellent clarity on all frequency range. You will hear each note with breathing air around it. The sound is smooth and well balanced.
FYI, more info from a independent review.
Output Load Impedance
Rated for 8 ~ 600 Ω loads.
(measured output source impedance is 15 Ω LOW, 50 Ω HIGH.)
HIGH output (600 Ω load)
-91.7 dBV A-weighted.
-83 dBV unweighted.
LOW output (37.5 Ω load)
-98.0 dBV A-weighted.
-91.0 dBV unweighted.
OK here is a link to copy and past for all the results of the amp.
kenrockwell.com/audio/woo/wa6-se.htm#z