PMB500
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PMB500 - Overview
PMB500 is one of the two models of electrostatic headphones produced by MB Peerless in late 1970's and early 1980's. PMB1000 seem to be the fully open top of the line monitor model, with PMB500 being second, possibly the cheaper model, of the lineup. PMB500 has the same float frame but different earpads that enclose the ear completely as apposed to "earbumps" used by other float models that leave the ear open. This results in a slightly smaller soundstage but very tight and punchy bass.
PMB500 comes with a transformer box that supples bias and allows hookup to a power or integrated amplifier. The technical specifications for both models seem almost identical. It is also not clear if the same transformer box is used with both headphones.
 PMB500 picture 1 |
 PMB500 picture 2 |
 PMB500 picture 3 |
 PMB500 picture 4 |
 PMB500 drivers |
 PMB500 driver closeup |
 PMB500 with energizer box |
 PMB500 vs SRD6 |
General Description of the Sound
Below are my listening impressions from the Brooklyn head-fi mini-meet at which I was able to spend a significant amount of time listening to PMB500:
PM500 are great headphones. Are they better than SR-Lambda? Yes and no, they are different. PMB500 have very precise and analytical nature, but still have immediacy and involving midrange. They still manage to create a very good soundstage, just not as good as other Floats and Sigma. I loved these for metal, they are very fast. Faster then SR-Lambda and just a little behind SR-303 when it comes to speed and decay. Over all these are wonderful headphones and they benefit greatly from a good amp. They sounded a lot better on my larger class A Tube-MOSFET hybrid amp.
Below are Facelvega's impression upon initial listen and at the mini-meet:
Listening now for the last couple of hours, comparing the PMB500 back and forth with the SR-Lambda and SR-X mkIII with various music, I can make a few comments. First, with a little extra use, the limitations of the PMB energizer are not so painful, they do make loud sessions with music that demands large instantaneous draw impossible, but I only really listen like that when I'm testing gear, so it isn't a big concern. Yet I still wonder how much that energizer is holding back the 500 in other ways less immediately audible.
As for performance, I think I can at least safely say the PMB500 is better than the SR-X and not so good as the SR-Lambda, particularly when it comes to frequency extension. The PMB has a character unlike either Stax, more forward and intimate, warmer with sweeter mids. It is better for most rock, say, than either Stax. It lacks the lower end of the Lambda, with a bass weight only comparable to that of the SR-X and never capable of the lush fullness that the Lambda can give. Treble on the PMB500 is a bit recessed, and sounds much more like one of the Stax if I add a few notches of treble EQ. (Before I tried the EQ I thought it was rolled off, but it isn't, it's all there) Soundstage is quite good, but oddly unlike the Lambda's, capable not only of distance but also closeness, though probably not as broad as the Lambda in absolute terms. Also, the PMB seems to be less fatiguing than the Lambda over the long haul.
The PMB500 is very close to the Lambda in size. The Lambda earpieces are slightly narrower but also much thicker, and it's clear eyeballing it that the Lambda drivers are bigger than the PMB's, mostly in vertical length. The PMB cable is thin, one rubber sleeve that seems to be holding the wires loosely in a bunch. It's single-entry, with the right channel being carried over in the headband. The PMB is quite comfortable, though clamps slightly more than the other MB floats I've had, leaving it a notch less comfy than the Lambda but miles ahead of the SR-X. One technical annoyance, the PMB has a floating channel imbalance that sometimes shows itself after I've been listening for a while, but never when they're first on, making me once again suspect an energizer issue as this is the opposite of a normal stat imbalance symptom.
I hope this satisfies for those who wanted a report. I'll probably have more to say soon, and there's talk of a Brooklyn mini-meet soon, so you can hear some other impressions.
edit for reference purposes: the PMB500 grows on me. With better amping, its bass response overtakes the SR-X and loses nothing much to the Lambda except maybe for some of the Lambda's "bloom." What first struck me as recessed treble now sounds like a more flat response than the Lambda. It's easily just as good as the Lambda, a really fine headphone. How must the PMB1000 sound?
I was a little nervous of how the PMB500 would fare up against these fine stax options. Already in my own system, I'd determined that it falls above the SR-X but below the SR-Lambda. Also, it seemed to have certain problems with deep bass, with amp handling, and with an occasional channel imbalance, though I've been noticing these things getting better with use, and I understand the headphone hadn't seen much head time in the months before I bought it from Digitalmind. F2D also speculated that its energizer might sound better with different amping. Nervously, I brought it along today.
I shouldn't have worried. On Faust2D's amps it performed like a champ, laughing off allegations of weak bass slam, eating up huge amounts of current, and with no channel imbalance to speak of. It was right up on the level of a Lambda, no question, but still not sounding much like a Lambda-- a bit narrower in soundstage, a bit flatter, with a faster attack; it particularly loved rock and metal, and as I discovered in testing yesterday, dance music as well. When I think that I paid less for these than for my SR-X, I'm dumbfounded.
Pricing & Other Data of Interest
I have never seen PMB1000 or PMB500 come up for sale on internet action sites. The only PMB500 that I heard was acquired from it's original user in Netherlands by one of the head-fiers. The only price information comes from the original owner that remembers paying approximately fl.960 in 1986, that would be a rough equivalent of $500 in 1986 money. I would estimate the cost of the a set today would run anywhere from $250-$600 depending on the condition.
Technical Specifications:
Below is the blowup from the original brochure (in German) that outlines the technical specifications:
