Audio Zenith – New PMx2

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(You can read some impressions of the PMx2 on Head-fi.org)

Introducing the brand new PMx2!

It has been a bit over three years of continuous development and well over a year of production. The main things we kept working on were streamlining the modification process in a way that it would actually make sense to produce PMx2 without losing time and money on every pair. We realized that no matter how good your product is, acquiring new customers without the help and support of local dealers and distributors could be extremely difficult. Therefore, in order to attract these dealers, we had to raise the retail price. But, for the new price to work, we had to make major upgrades to sound quality and design.

Many agreed that frequency response of our PMx2, top to bottom, is where it generally needs to be. The main areas that still needed improvement were distortion, resolution, soundstage and possibly even looks.

Remembering how some were concerned with durability of velour we decided that leather earpads would help, while also enhancing the looks.

Easier said than done, especially if one wants to keep the correctness of original tone. Nevertheless, our measurements below show that the tonality is generally the same. Feedback from the first listening tests demonstrated improvements that we didn’t necessarily expect. Airiness, soundstage, imaging quality and size reportedly got better.

Another welcome change was to visually differentiate new PMx2 a bit further with silver painted grills.

Distortion is the achilles heel of the OPPO driver we use and we have been fighting with it pretty much right from the start. With a bit more hard work, the new measurements show that the PMx2 distortion on average is 3-5 times lower than original OPPO and is finally on par with the best TOTL headphones available.

In fact, up to 90db,total distortion measures exemplary 0.235% and a vast majority listen at much lower levels than that. When SPL is increased above this level, the knurled portion of a diaphragm greatly affects the sound boosting low frequency SPL and generating a fairly narrow spike of distortion around 300Hz. Our goal was to normalize the diaphragm motion.To do that, we had to reengineer the original magnetic and damping structures. The results are displayed on the graphs below.

Taking into consideration all the controversy around our previous measurements, this time we wanted to show how the PMx2 frequency response graphs change depending on the properties of the coupler. We took three different measurements of the same driver.

The first coupler was most suitable for a closed back design, with minimal absorption and the highest air pressure maintained within. The second coupler was built using instructions on SBAF headphone measurements section and is similar to one used by many members here. Thethird coupler is what we believe to be the most realistic representation of how listeners are actually hearing our headphoneand can be verified using online test tone generators similar to this one: http://onlinetonegenerator.com/frequency-sweep-generator.html

The pricing for the modification of customer’s sets of OPPO PM-1/PM-2 was increased slightly to $899.00 which, unlike before,includes a new set of earpads ($59.00 plus TAX and shipping, directly from OPPO).Basically the real price difference for modification is $135.00 vs previous version of our PMx2.

Price for the brand-new Audio Zenith PMx2 (the only one with silver grills) is now $1899.00.

Oppo PM-2 and Sennheiser HD-650 distortion measurements at the same 95db on the same coupler were given for comparison purposes only.