Bests & Worsts Reviews from Amazon

There are two Amazon product pages for the same Sony Bluetooth Noise Canceling headset: - The MDRZX770DC is sold in Discount Clubs such as Costco. It comes in a huge box which contains a hard case for the headphone. - The MDRZX770BN is sold in retail stores such as Best Buy. It comes in a smaller box and does not contain a hard case. I have previously purchased the older model (Sony MDRZX750DC Wireless Bluetooth Noise Canceling Headset), but returned it due to two major flaws: it is uncomfortable to wear over extended period, and cannot be used as a stand-alone noise canceling headphone. Recently I found this new model (MDRZX770DC) in my local warehouse Club, and decided to give it another chance. Here are my findings: One major improvement over previous model is immediately noticeable: The ear cups are much larger than before. They now cover around my ears, instead of resting on them. The cups are also larger than that of my other around-the-ear headphone, the Able Planet NC500SC Sound Clarity. So I can wear the Sony headset for hours without hurting my ears. [Bluetooth] The Bluetooth function works smoothly with my cell phone (Samsung Galaxy S3) and tablet (Lenovo IdeaTab A8-50). I can answer phone calls with the headset's built-in microphones, which are normally used for noise canceling function. Pairing was fast, and the range is better than advertised. Spec sheet says around 30 ft with line of sight. In practice I can get close to 50 ft before signal becomes intermittent. There is however one problem with using Bluetooth: When watching movies in Bluetooth connection mode, the audio is lagging slightly (maybe 0.1-0.2s) behind video. This may ruin your movie viewing experience, since the audio appears out of sync with lip movements (unless you only watch dubbed movies, in which case the audio is already out of sync anyway) [Sound quality] According to the spec sheet, the frequency range is 20Hz to 20kHz when using Bluetooth connection. It gets even better when using audio cable: 8Hz to 22kHz). In practice it makes absolutely no difference to me, since I am not an audiophile, and my ears are too old to pick up anything higher than 12kHz, anyway. When using audio cable, I can power down the headset and the music still sounds as good. Naturally, the NC function is not available when there is no power. This means I can still use it as a normal headphone after the rechargeable battery runs out. It is also important when I'm traveling by air, since some airlines insists that "All electronics must be turned off during takeoff and landing" (even though the NC headphone does not emit any detectable EMI) [Noise-Canceling Function] There is a button labeled 'NC' on the left ear cup. In Bluetooth connection mode, I can press this button to toggle Noise Cancellation function on/off. But when connected using audio cable, this button does nothing. So the only way to disable NC in wired more is to turn off the power. Just like all my previous noise canceling headphones, the MDR-ZX770 uses active noise canceling technique. It works great in neutralizing low-frequency background noise from fan, air conditioner, jet engines, etc. But it does not work well on office conversations or high-pitch sounds such as siren. Here is my problem: in my lab area there is a constant low-frequency humming noise from fans and AC vents. Occasionally there is also high-frequency hissing sound from liquid nitrogen tank. The NC headphone does a good job in getting rid of the low-frequency noise, but is ineffective in the high-frequency range. So now the hissing sound appears even more annoying than before! During my most recent trip, I took both the Sony MDRZX770DC and the Able Planet NC500SC for an A/B test on the plane. The Sony model does a significantly better job in reducing the engine noise. [Auto-off function] If Bluetooth connection is not established, the headset powers off automatically after 5 minutes. That means I cannot use it as a stand-alone noise cancellation headset. One workaround I found for the old ZX750DC headset still works here: insert a dummy audio plug into the 3.5mm audio input jack. The unit then stays on indefinitely even without any signal from the jack. Note that if I power up the headset with an audio plug connected, the Bluetooth function will not be activated. When I remove the audio plug, the unit powers off immediately. If I reconnect the audio cable, the headset stays in power off mode. I can still hear the music, but the NC function is not available. [Other remarks] - Internal battery run time is advertised as ~13 hours when using Bluetooth and NC function - Recharge time is ~2.5 hours. USB charging current ~200mA (the included AC charger is rated 1.5A) - You cannot power up the headphone while it is being recharged. So it can only be used as an un-powered headphone (without NC) through audio cable. [Bottom Line] The Sony ZX770DC made an improvement over the previous model, in that it offers larger around-the-ear type ear cups. It is a shame that it still cannot operate as stand-alone NC headphone without using my 'dummy plug' trick. For the warehouse price I paid, I consider a good, but not excellent, product.