Date: 2022-05-23

The loudspeaker company PMC has an excellent reputation both in the studio and in the home. And their designs are based on a technology that almost no other manufacturer still plays a role in.

PMC co-founder Peter Thomas said in an interview that his fascination with audio reproduction began with his grandfather's wind-up gramophone. At first he couldn't believe that music could actually come out of such a funnel and wanted to know why. Around 1970 he started with DIY projects until he heard the first really good commercial speaker - an IMF Transmissionline. He and his best friend and later partner Adrian Loader fell in love with this special sound - this is where the story of PMC begins.

Thomas had previously worked for years as an engineer in studio services, later in project development at the BBC. There the engineers were taught every aspect of the subject: from the microphone to the tape machine, including service and construction, they simply learned everything that later came in very handy.

Thomas was then given responsibility for the listening comparisons between the original BBC speakers and licensed models from other companies. At the same time, he began to develop his own loudspeakers. And as it happens in life: One day the BBC needed larger studio monitors and so Thomas and Loader produced the desired monitor under the quickly found name PMC - Professional Monitor Company. But that also meant leaving the BBC, which was not easy for him, but otherwise he would not have received license fees for his loudspeakers.

By the way, this first loudspeaker was called BB5 (Big Box 5) and was built for 25 years. And since the BB5 was initially the only product from PMC, the opposite of it was built for commercial success: A small monitor, also with a TML (Transmission Line), appropriately called LB1 (Little Box 1). And that is exactly the ancestor of our twenty5.21i. From the beginning, PMC made no distinction between professional and private use, so Thomas points out that the tuning is always the same. The hi-fi sector has meanwhile come a long way commercially from the pro segment and has even overtaken it in some areas. So with a PMC you get speakers that - or closely related models - have been used to mix the music you're listening to.

This is also the opinion of Udo Besser from AVM, who has been using PMC loudspeakers at home for a long time, since PMC is the AVM distributor in Great Britain. A friendly relationship had developed over the years and it was logical that he took over sales at the beginning of 2022. In any case, PCM is a real family business in which all members work.

But even if PMC is very traditional, the company works in a highly modern way. And even if the English simply have to love that they have remained true to a design principle such as the transmission line, which is really not easy to master, they have been researching it for decades and today call the technology ATL for "Advanced Transmission Line". The bass is placed at the end of a long tube - the "Advanced Transmission Line" - which is heavily damped to eliminate unwanted rear frequencies from the driver. The air outlet at the front, PMC calls it "Laminair", is visually striking, technically very effective and regulates the considerable air movements from inside the housing. Only the lowest frequency components come through and exit in phase to act practically like a second bass chassis. The air pressure in the housing, which loads the bass, remains constant. This ensures that clean, undistorted bass and frees both the upper bass and the mids from harmonic distortion. This ensures enormous transparency, which I can definitely confirm. This is joined by an insanely fast, dry bass and a spectacularly high undistorted overall volume. The box sounds enormously homogeneous and rich in detail, even at very low levels.

The vertical range of manufacture at PMC is enormous. Not only are most of the drivers in-house produced, the LS connectors are made in-house from pure copper plated with rhodium. They are characterized by a very high conductivity and low resistance and are wired directly to the crossover. And PMC attaches great importance to the exact pairing of all drivers. This is especially necessary in the professional field, where, for example, a Bryan Adams would like to hear the piece he has just recorded in the studio as well as at home without experiencing any changes in the sound from the loudspeakers.

The packages for the PCM-ATL technology are not easy to manufacture. In addition to drivers with very specific parameters, you need a sophisticated housing design with reinforcements and very effective damping, which is why TML technology has almost gone out of fashion. The effective length of the TML tube alone is an incredible two meters in our compact model! But this is how PMC has almost achieved a unique selling proposition.

The ferrofluid-cooled dome is built by Seas for PMC, and the company manufactures the mid-bass driver itself. Its finely woven fiberglass cone with an inverted dust cap made from the same material, very strong magnets, long-throw voice coils and a sophisticated surround minimize distortion - that can be measured and heard. The crossover for the twenty5.21i separates with a steep 24db and works with highly selected and aurally tuned components. And how does the twenty5.21i sound? In one word: fantastic.

I immediately notice the extremely clean reproduction, which reminds me of the water from a crystal-clear mountain stream. The twenty5.21i plays extremely naturally with a completely believable three-dimensionality. With Triycycle by Flim & The BB's it sounds incredibly closed and at the same time incredibly stable and is practically impossible to push to its limits. And then the bass: never fat or thick, but if you really want to know how much undistorted, uncompressed bass can come from almost 30 liters of cabinet volume: voilá. Drums and bass bang into the listening room in an impressive manner and there really seems to be no limit to the twenty5.21i. She also loves voices. For example, when Carolyne Mas sings live, I sit in the middle of the audience. Here, too, the bass springs dry and sparkling clean and Mas' voice almost jumps in my face. The freedom from distortion of the twenty5.21i can be heard at any time and yet it never feels sterile. The live recordings of the ingenious banjo master Bela Fleck with Chick Corea are also good for this. "Bang" Fleck accidentally hits the microphone and after everyone is awake again, a journey into the finest ramifications of transient speed, microdynamics and timbres begins. Small speaker, big audio cinema. begins a journey into the finest ramifications of transient speed, microdynamics and timbres. Small speaker, big audio cinema. begins a journey into the finest ramifications of transient speed, microdynamics and timbres. Small speaker, big audio cinema.

Conclusion
The PMC twenty5.21i makes you forget its compact size from the first notes. She can do almost anything and plenty of it. Sensationally good speaker.

Read the twenty5.21i technical data: https://bit.ly/3yOV7Sn

Date: 2022-05-16

Review by: Dave McNair

Journey To Ixtland
When I first started writing for Part-Time Audiophile, Scot Hull and Marc Phillips asked me if I wanted to do some cable reviews. I replied something like, “I’m not a believer. Since becoming a mastering engineer I’ve never been able to hear differences in wire, so no, I doubt I’d ever want to review cables.” I then proceeded to skewer anyone on the PTA staff who were believers as having fallen prey to psychological mental traps, as well as common errors in judgment called scientific names such as confirmation bias, aka The McGurk Effect. “Stella, look at all these pretty Siltech Classic Legend 880 cables. Don’t they sound fabulous?”

Words and Photos by Dave McNair
Well, times have changed, y’all. I now can confidently attest to being able to hear differences, albeit very small ones, in cables. WHUUT? I know. Makes no sense whatsoever. The naysayers will be like, “Oh boy, he drank the Kool-Aid.”

The true believers will exclaim, “Now he knows. Welcome to the club.”

Not so fast, Franklin.

After being an avowed tweakaholic in my earlier days (yes, I even used The Green Pen on CDs), I made a hard turn into a test methodology that showed me conclusively that all that kind of stuff was complete mass hysteria. I’m tentatively back.

But this time, things are a little different.

Siltech Classic Legend 880–The Loom
Like many readers, I’ve heard the Siltech name for years. That’s not surprising, given that this Netherlands-based operation has been making cables since 1983. From the beginning, Siltech has been heavily invested in research to determine the hows and whys of perceived sonics. The company wanted to determine if a change in perceived sonics could be measured. Apparently, it can. Siltech correlates perceptions with those measurements for use in design and manufacturing methods in their various lines.

If you’re a cable denier, I know what you’re thinking. Just because it can be measured, does that make it audible? That was my line of reasoning but let’s go with it for a minute, okay?

Siltech (SILver TECHnology) is usually associated with the fundamental concept that silver is the best metal for cabling. However, there is more to the story. The entry-level Explorer series, for example, uses a very pure 6N mono crystal copper with a mix of Kapton and Teflon for insulation.

The next level up is their Siltech Classic Legend series, which includes the Anniversary and Legend. The top-shelf Royal Signature line consists of the Crown, Double Crown, and the uber high-end – Triple Crown series. The Triple Crown and Double Crown series use monocrystal silver, the others use predominantly silver with a small amount of gold. The silver/gold metallurgy is said to be used as a method for filling microscopic cracks in the silver to create more continuity for an electrical signal to traverse.

The Siltech Classic Legend 880 loom I’m reviewing here has SIltech’s ninth generation G9 silver/gold conductors and a combination of Teflon and PEEK (Polyether ether ketone) for insulation. I found out what those bulky barrels on the ends of the cables are for, and it’s not just the bling factor. The barrel allows the fat bulk of the cable to have slimmer, easier to deal with terminations. The barrels also features indicators for proper direction, as well as the model and serial number.

The technical and subjective descriptions on the Siltech website, by the way, are fascinating. There is a lot to digest and it’s not of the typical marketing-copy variety, either. I got the distinct feeling these guys are not playing around.

Test Methodology
After years of looking for ways to quantify small changes in sound for an audio device under test (DUT), I’ve found some guidelines that work for me. While searching for a signal path with the least or most pleasing color for use in my mastering chain of gear, it’s important that I don’t fool my ear and buy something that is initially exciting but will end up not as likeable in the long run. It’s happened before. I figured out that what I thought was an amazing ADC or DAC or equalizer, turned out to simply be a little louder than what I compared it to. So the first rule is scrupulous level matching.

Most audio peeps know that aural memory is short and fleeting, so I have to be able to instantly switch. Then, just as important, simply switching during the flow of music is not a great idea because the music is constantly changing. I’ve switched while a song plays and thought device B was a little warmer. Turns out that exact second I switched was when the vocalist got a little closer to the mic, or something of that nature. So here’s how I get around these issues.

I devise a way to record the same music playing through the DUT and my control device, line both files up in my workstation, and make sure the levels are as close to identical as I can. Then I pick a few bars, maybe five or six seconds, that have lots of information. Then play I that looped section about five or six times, which pounds the character of a vocal sound or transient impact or image cues into my brain. THEN I hit a button that routes the version recorded through the DUT to my system. Sometimes I shuffle the deck, so to speak, and it becomes more of a blind switch.

I’ve heard lots of audiophiles dismiss instant switching for a variety of reasons. I can maaaybe get behind “the switch-has-too-much-of-a-sound and will obscure small differences.” My method only changes the digital routing. It’s totally colorless. I’m using a mastering grade Prism ADA8-XR for conversion and while not being 100% neutral, it has all the resolution I need for comparisons.

The other assertion is that you have to listen for a long period of time to adequately internalize the subtleties of some sonic signatures, like cables. I call bullshit on that one. Our brains just rewire over a long enough time period. It’s science. Look it up.

I’ve used this test methodology several times before in hi-fi reviews and it’s always instructive. In fact it’s how I finally came to hear small differences between line-level cables. Obviously, not all components can be tested in this way–power amps, speakers, and speaker wire come to mind. But cables are a natural.

Siltech At The Studio
The system at the studio consists of a pair of Acora Acoustics SRC-2 loudspeakers powered by a pair of Pass Labs XA-200.8 amps and fed by my custom Knif Audio mastering controller. Jonte Knif is a Finnish audio genius who builds an audiophile-level mastering controller with a minimalist, single-ended design using his own discrete op-amps, select Analog Devices chips, and Elma switches. It has a superb yet extremely subtle sonic imprint. The monitor output of the Knif feeds a Prism Sound Dream DA-2 as the monitor DAC which I had connected to the amps with Siltech Classic Legend 880.

Here’s what I heard:

I used two great-sounding, pre-mastered mixes off of a recent mastering project, 24bit at 96K. I plugged the (source) DAC into the ADC (one Prism Sound ADA8 XR does both) with a variety of balanced XLR cables and recorded at 24/96 in my Sequoia workstation. This is commonly known as a loopback test. The test samples were Mogami 2549, Terry Audio chrome pin, Cardas Clear Beyond, and the Siltech CL 880. I compared captures of the different cables by lining them up on separate tracks fed to different outputs, digitally switchable on my console to the monitor DAC. Once the listening volume level was established, I never changed it.

When I was casually listening at a lower level and the Siltech versions were being recorded, I freaked out and heard what seemed like stark differences from the previous cables.

Once I finished recording everything, lined up some combinations, found a good listening level, and picked some sections to pay close attention to, most but not all the casual listening differences disappeared. The key phrase here is but not all.

The Mogami was solid but nothing special. Maybe a hair thinner in the lower midrange and not quite as dynamic as some of the others, although the sense of detail was good. The Terry Audio cable seemed to have the most color, but in a pleasing way. A hair darker, yet smooth and harmonically beefier but also a little more congealed sounding.

The Cardas and Siltech were the clear winners. I could hear why I’ve enjoyed Cardas in my system for a while now. It just sounds right. The Siltech, however, had a very pleasing overall tonality with a smidgen more fresh air on top and size in the low end, and also a slightly greater sense of dynamic contrast. It almost sounded louder than the others. I heard more complexity to the amount of information that I usually associate with a pleasing kind of coloration, but this was different. Lots of harmonic micro detail and size, without getting blurry.

I then listened to long stretches of the tunes in a less analytical way, which was difficult at this point but not impossible. Something about the flow and juiciness of the music was greater with the Siltech. Confirmation bias? Maybe, but it was real to me and that’s kind of the whole point. If the listener hears something he or she thinks is worth owning, who is anybody to say otherwise?

Lastly, I compared all the cable passes with the source mix. The source mix was clearly the best. My Prism ADA8 XR is fantastic, but no converter is perfect. So which pass sounded closest to the source? None of them. One listener I invited to hear the results felt that there were more differences between cable types than between the Siltech pass and the source. But the best cable is still no cable. To be fair I can’t remove the sound of the Prism converter from the test although I think it’s valid for comparing all passes recorded through it.

Back At The Crib With Siltech 880
Since it takes too long to unhook and swap out an entire group of cables with any real hope of retaining enough aural memory for the minuscule differences between cables, I didn’t do much of that. I did do that a few times with the speaker cables, but even that proved to be inconclusive. It’s not that I didn’t hear differences when swapping out for my reference Cardas Clear Beyond speaker cable, it just didn’t seem stark given the length of time between samples. I should also mention that during the review period I also used Siltech power cords on the DACs, preamp, and power amps.

Yeah, let’s talk about power cables for a minute.

I saved this test for a lazy Sunday afternoon when my ears and mood were in good shape. I wanted the test to be as much of a stark contrast as possible because in the past I have never been able to hear any difference whatsoever in fancy power cables. I mean, really? How could it possibly do a damn thing as the last few feet in a long chain of mystery wire and connections? If the power supply in a component is correctly designed all should be well with any old decently made power cord, right? Apparently not, mi amigo.

For this test, the core system consisted of the most excellent Von Schweikert Audio Ultra 55 loudspeaker, Valve Amplification Company Master Preamplifier, and Parasound JC-1+ power amps. Later I added the newest offering from VAC, a pair of insanely great-sounding Master 300 Musicbloc amplifiers.

I selected the Ideon Audio Absolute (make mine a double with a twist) that I have in for a review, as my power cable Guinea Pig. Spoiler alert: the Absolute is the best sounding DAC I’ve yet to hear in my system.

I tested the Siltech Legend series 880 power cord against a beefy gauge, but generic black power cord. To make it even more interesting I did this comparison in two ways: with the cords plugged directly into a standard duplex wall socket OR plugged into a Cardas Audio Nautilus power bar. I didn’t have enough Siltech power cables on hand to run the amps, preamp, DAC, and the power connection from the Cardas bar to the wall plug so I used a Cardas power cable there.

SONOFAMOTHERFLIPPINGUN. Although subtle, I heard differences. A larger observable sonic contrast between the straight outta wall comparisons, but the results were similar even after some love from the filtered Cardas power bar.

I used two tunes for this test, “Qualquim Coisa” performed by Caetano Veloso off of Los Super Seven – Canto, and “Fast As I Can” from the Fiona Apple album When The Pawn…

The stock cable was just a little bit more nervous and jumpy sounding. Less separation of textures, and generally a mite edgier. Similar to the line-level cable tests, the Siltech 880 power cords almost seemed a bit louder, certainly more fluid, and refined. Textures had a tighter weave to the fundamental flow of the music and things just sounded more expensive. The differences were more subtle using the Caetano Veloso song, even though I know this one well having recorded and mixed it–all analog tape, no less. I’ve noticed many times that very open, minimalist recordings like this one sound pretty effin awesome regardless. But the density and wider pallet of harmonic flavors, and transient information in “Fast As I Can” proved conclusive.

I am fully able to admit to confirmation bias for the power cable and speaker cable tests. I would not swear on my life that these differences were anything other than what I thought I wanted to hear. But on that day, with those tunes, and whatever mindset I was in, I heard what I heard. And I liked it!

Unlike the IC and power cord tests, I didn’t come up with anything conclusive for speaker cable comparisons. It simply took too long to switch. The Siltech and Cardas cables both were spade lugs, and the amp and speaker posts were a variety that was not quick and easy. I don’t trust a comparison that has many minutes in between samples. And as previously stated, I give much less credence to long-term observations because the brain has a very strong tendency to adapt and rewire itself to long-term sensory input. My real reason for wanting to live for a while with a component under review is to average my impressions owing to different moods over several listening sessions. How many times have you sat down to play some music and thought “ Wow, my system is killing today!” Or, “Why does everything I play sound kinda shitty, tonight?” It happens to reviewers too.

The possible exception for me not putting much weight into long-term listening impressions are DACs. I’ve found many DACs will initially sound quite similar, yet extended listening will reveal over time what my ear may grow not to like. My pal and colleague Grover Neville likes to say the best sounding DAC is the one that, over time, you find the least offensive. For me, cables may also exist in this subtle but ultimately meaningful area as well. I will point out that I did hear a bit more clarity when I made some comparisons to Siltech 880 speaker cables when Credo EV One speakers were in the system. At the studio, I was able to set up a more rapid swap on the Acora/Pass Labs system. I heard some small changes there as well, so the speaker cable thing wasn’t a total wash.

Jon Baker and Rich Maez, of Siltech distributor Monarch Systems, were kind enough to send the proverbial baker’s dozen in the form of a Siltech USB cable so I could compare that. I have done digital cable comparisons at my studio and they always null 100% with a 180-degree phase flip which is the gold standard in pro audio tests. That means zero difference. I didn’t try the Siltech USB at the studio but did do a few swaps for a generic USB cable going from my Innuos Zen Mini streamer to the Ideon Absolute. Less conclusive than the power and IC tests but still, I heard something different happening. Really? Damn. Could I pick either in a blind test? No way, Jose.

Siltech Classic Legend 880 Conclusion

Well, I think I’ve said all that I wanted to say.

I didn’t say a whole lot about all the cutting-edge science in the design and construction of Siltech cables. Mainly because if I’m honest, I really couldn’t care less. How it sounds in my system and how much it’s gonna cost me are pretty much my only areas of interest, at least with cables. I don’t need fancy looks, complex science, and impressive packaging to be impressed, although Siltech most definitely excels in all those areas. And for the folks that like to know there is a definite science behind a design, Siltech may be the most serious player in this area.

I had a blast using the cables and more importantly, I learned that I can sometimes, under certain conditions, hear differences in cables. What does that mean for my system?

As far as the Siltech Classic Legend 880, I definitely felt they brought a new level of overall listening enjoyment to my ears in the form of a hard-to-describe sense of luxuriousness to the sound. If they have any major sonic signature it’s the same as all my other favorite components: large, complex, dynamically revealing, yet smooth. I will be a little bummed when they go back to Monarch Systems, although I’m perfectly fine with the performance I get using Cardas Clear Beyond. However, I very well may have to throw down for some at the studio. My kingdom for a power cord!

I feel like cables are the last tiny bit of seasoning on a perfectly cooked meal.

Does an expertly cooked meal that uses the best, freshest ingredients ever really need added salt and pepper? Does a few grains of salt on a perfect tomato at its peak, enhance the taste experience? How much would you spend on that salt? Is the value-added for the salt different for a tomato versus a steak? Does Himalayan, organic, free traded salt taste better than Morton’s? Is there a best type and source of pepper, above all others? Do these questions mean different things to a typical eater as opposed to a hard-core foodie?

I know what my answers are to the questions posed above. I’ll let readers answer for themselves.