PMC fact.8 signature loudspeaker

Back in the Dark Ages, loudspeaker design was commonly based on semi-enlightened experimentation, with new enclosure configurations appearing almost monthly in professional and consumer journals. One of those, published in Wireless World in October of 1965, was A.R. Bailey's transmission line, a long, selectively resistive, folded-and-sometimes-tapered tube that loaded the back of the (woofer) driver for low-bass reinforcement. The term "transmission line" was misleading; a transmission line in a loudspeaker is designed to absorb all but the very lowest frequencies of the driver's rear-going output, while the thing it was named for—the electrical transmission line—is designed to preserve as much of a signal as possible. Oh, well.

Shortly after the first commercial transmission line products emerged, from Radford Electronics in the UK, IMF Electronics adopted the concept and launched a commercially successful loudspeaker line. Infatuated by their products, I built several loudspeakers, both passive and active, based on IMF principles.

But the loudspeaker landscape was changing, largely as a result of two developments: the continuing rise of acoustic suspension (sealed box) designs, which had started in the 1950s, and, especially, A.N. Thiele's codification of the parameters for loudspeakers with ports (footnote 1), which occurred at about the same time that the transmission line was introduced. Now one could design speakers that were more compact and, in many cases, more efficient, with more predictable results. So, transmission lines quickly faded in popularity. As far as I know, The Professional Monitor Company stands today as the technology's most avid and important advocate.

As befits its name, most of PMC's products are made for the studio and pro-audio markets, and their large, matte-black boxes seem strong and serious (footnote 2), especially when stacked with matching subwoofers.

PMC's consumer products are a stark visual contrast with their professional ones, their lines svelte, sleek, and elegant. The fact.8 signature ($12,000/pair, footnote 3) is all that. According to PMC, the fact.8 signature and its larger three-way sibling, the fact.12 signature, are based on "trickle down technology applied from the fact fenestria," the top model in PMC's fact line. The crossover network, which employs noninductive Mundorf MResist Supreme Resistors and high-grade British-built ClarityCap Capacitors, derives from the development of PMC's flagship—and, indeed, the presentation and the construction of the compact fact.8 signature seem comparable.

The reveal
I slipped the fact.8 signatures from their boxes to find a pair of impeccable-looking slabs, finished in PMC's Metallic Graphite lacquer (Silk White is also an option) with decorative front grilles that attach with magnets and fit firmly and precisely. No seams, joints, or attachment hardware to be seen. Simply and cleanly beautiful.

The speakers came with bright chrome outriggers and floor spikes attached. The spikes were too sharp to spare my wood floor, so I inverted them to expose the ball tips and hen added the provided plastic boots. If there was going to be a lot of repositioning—and there was—I wanted to make sure the experience would not be permanently inscribed on my floors.

The three drivers are stacked closely near the top of the front baffle, with the 0.75" (19mm) Sonomex-dome tweeter above the dual 5.5" (140mm) mid/bass drivers. Cut-away diagrams show the mid/bass drivers back-radiating into the cabinet space in front of a vertical divider. The air pressure from these drivers passes above that divider, then down in the space behind it and through another chamber below all this, which extends to the front of the enclosure. The racetrack-shaped port of this 9.8' (3m) transmission line is close to the bottom of the front baffle.

It is not clear to me how PMC's "Advanced Transmission Line" (ATL) differs from classic designs. The company says that they've optimized various physical elements (drivers, crossovers, etc.) thanks to their "bespoke" acoustic simulation software, which they say allows them "to tune the cross sectional area of the transmission line at the start and end to be essentially as small as possible without compromising low frequency performance and upper bass absorption." The company's description continues: "The rate of taper is another factor that can be determined and optimized with the simulation so as to tune our transmission lines to absorb best the upper bass frequencies which are not desirable to transmit from the ATL Vent." The chamber at the back of the drivers is larger, relative to the driver area, than I would have expected, and there is a dilatation in the chamber just behind the narrow terminal vent. Otherwise, PMC did not provide technical information about what makes their ATL "advanced."

PMC promotional literature also mentions the effect of ATL on higher frequencies: "Because the low end is clean and clear, it doesn't mask the rest of the music. Vocals, in particular, are beautifully projected and ultravivid."

420PMC.bac

On the back panel, two pairs of silver-capped, multiway binding posts are linked by a pair of silver bridging bars, the removal of which allows for biwiring or biamping. Just above the connectors are two toggle switches. The lower one switches the LF response from its upper, "flat" position to either of two amounts of bass rolloff. The upper switch allows the HF output to be increased or decreased from its central, "flat" position.

Setting up
To start, I placed the fact.8s in the same positions as my resident speakers, but the results there were disappointing. The treble was in my face, the midbass was on vacation, central images were distant, and the only evidence of a bottom end was some indeterminate bumps. There was clearly a lot of work to do. PMC suggests 50 hours of "running in" time for optimal performance, so maybe that was part of the problem.

I found that the fact.8s needed to be much closer to the wall behind them than other speakers that I have had in this room. Pushing them back to less than 1' from the wall filled in the bass and restored some harmonic balance.


Footnote 1: Thiele, A. Neville (1961), "Loudspeakers in Vented Boxes," Proceedings of the Institute of Radio Engineers, Australia, 22(8), pp. 487-508. Reprinted in Journal of the Audio Engineering Society, 1971, 19(5 & 6), pp. 382-392 & 471-483.

Footnote 2: I reviewed their IB-1S in 2005.

Footnote 3: I'll respect the manufacturer's avoidance of standard capitalization.

COMPANY INFO
The Professional Monitor Company Limited
US distributor: Motet Distribution Inc. (a division of XLO International Inc.)
90 Nolan Court, Unit 30-32
Markham Ontario L3R 4L9, Canada
(905) 474-433
ARTICLE CONTENTS

COMMENTS
Bogolu Haranath's picture

May be KR could review the new Magico A5 speakers ($22,000/pair) :-) .........

JRT's picture

Any reader of this review looking for a very much better transmission line loudspeaker at fraction of the price should consider the Salk Silk Tower, at the link below:

http://www.salksound.com/model.php?model=Silk%20Tower

Bogolu Haranath's picture

They use RAAL ribbon tweeters, which are very good measuring (and, sounding) ribbon tweeters :-) ......

JRT's picture

Yes, the Salk Silk Tower uses RAAL ribbon tweeters and ScanSpeak Illuminator midwoofers, excellent drivers utilized in a well designed loudspeaker. The cabinets are very nicely made, and for moderate upcharge Jim Salk will apply a bespoke veneer of the customer's choosing.

(edit: On reflection, I see that this does read like SPAM, but I have no financial interest in any of this.)

To give some credit where credit is due... My understanding is that R. Dennis Murphy designed and developed the crossover, and Paul Kittinger designed the transmission line enclosure using Martin J. King's Mathcad worksheet(s).

Martin J. King has done a lot to advance the art and science of modeling quarter wave transmission line alignments, and also developed accurate characterization of the behavior of stuffing/damping material utilized at key points within those.

MJK's website:
http://www.quarter-wave.com/

Some good info on TLs:
http://www.quarter-wave.com/TLs/TL_Theory.html

Bogolu Haranath's picture

SP(iced H)AM :-) ......

SPAM n' eggs :-) ........

Bogolu Haranath's picture

Bose 'Acoustic Wave' systems use a type of transmission line technology :-) ........

RH's picture

JA: "The PMC fact.8 signature's measurements do correlate with the sonic character Kal reported, I feel."

Fascinating. As soon as I saw this review I wondered if the reviewer would hear what I did, and if it would show up in the measurements.

I spent some time (over a few different days) listening to the PMC fact.8s (IIRC, it was that model), and I heard the same thing reported by Kal. Clear, clean and brilliant high end, but I found the lack of warmth "rather uninvolving."

I continue to value Stereophile's combination of subjective reviews with objective measurements!

Bogolu Haranath's picture

Your favorite Joseph Audio Perspective2 Graphene is close in price ....... It would be interesting, if JA1 provides in-room FR measurements comparing the Joseph speakers with this model PMC speakers :-) .......

RH's picture

I think this can already be seen when comparing the stereophile measurements of the Joseph and PMC speaker. The Joseph speakers also have a very clean, clear sound while maintaining a more even richness in the lower mids/upper bass. Not a "fat" richness, like an old Spendor or a Devore O series speaker (which I also enjoy!), but enough to not feel robbed. That's the type of balance that attracted me to them in the first place.

Bogolu Haranath's picture

Yes ..... These PMC speakers have a 'dip' from 100 Hz to about 500 Hz ...... also, another 'dip' from 1.5 kHz to about 6 kHz in the FR :-) .......

latinaudio's picture

Every time I read JA measurements, I think the same: don't manufacturers have access to equipment like the one used in Stereophile? I think so, they must have it because that is their goal: to create speakers with the fewest defects. Most of the time they are easily correctable things, without major costs. "Those looking for more mid and high bass weight should listen to the fact.8 carefully before buying"... and I need to pay $ 12,000 for this outstanding limitation? If the final product is so low in its performance, the final price should also be low...
Bogolu Haranath: now I understand you!!!

Bogolu Haranath's picture

I agree with you ...... At least, those manufacturers should listen to speakers in their price range, before bringing them to market :-) .........

hb72's picture

some electronics manufacturer offer products that tend to have the characteristics opposite to those mentioned for the PMCs, ie I read some Naim amps, especially when "HiCapped" (add-on PSU for pre-amp stage), tend to have a more pronounced (yet funky!) mid-bass, so that a combination of NAIM & PMC *might* gel quite impressively (helped by suitable speaker cable joice etc), also (or shall we say primarily) w.r.t. famous PRaT.
In other words, its the system neutrality that counts, not so much the neutrality of each and every component, though of course, the latter makes system building a lot easier.

Kal Rubinson's picture

Here's my take. I think that most of them employ intelligent engineers and designers and that they provide them with adequate technical support. However, it is the role of management/owners to decide what product they want to offer including price range, size, materials technology, appearance, finish and sound character. The company then creates those products. Just as with the audiophile market, there are different preferences among the manufacturers. Just IMHO.

Bogolu Haranath's picture

May be the management/owners like only sopranos but not baritones ...... Just kidding :-) ......

Bogolu Haranath's picture

If Louis Armstrong sings 'Show Me How You Burlesque', he would sound just like Christina Aguilera :-) ......

Bogolu Haranath's picture

On a side note ....... May be KR could review the new Legacy 2, 5, 7 channel ICEedge Class-D amp, 610 WPC X 7, into 8 Ohms, $7,950 :-) .......

Ortofan's picture

... ultimate transmission line type speaker:

http://6072m.net/TDL_Reference_3.pdf

Bogolu Haranath's picture

Take a look at the PMC fact fenestria TL speakers ($65,000/pair) :-) .........

Ortofan's picture

... the mid-range driver.

Bogolu Haranath's picture

I know ..... The midrange driver is isolated just like the tweeter, which is ideal in a 3-way speakers ...... Mid range is not interfered by the bass frequencies ....... TL usual principle is to extend and increase the amplitude of bass frequencies, not the midrange or treble :-) .........

Bogolu Haranath's picture

You can read about 'Transmission line loudspeakers' in Wikipedia :-) .......

Bogolu Haranath's picture

KR also, wrote about the principles of TL in his review of PMC IB-1S speakers :-) .......

DavidParis's picture

Well, that's a pity. I've been planning to audition and hopefully acquire the new PMC Twenty5 23i for use with Naim electronics. It's clear that the fact 8s are different animals but many of the design principles are similar with PMC's other models. Clearly, neutrality and linear response seem to correspond to a "house" philosophy and may not please everyone. For the 12K USD expenditure, I would've expected a more impressive and certainly better balanced result.

Bogolu Haranath's picture

For the price of PMC Twenty5 23i, you could consider Monitor Audio Silver 300, reviewed by KR for Stereophile :-) ........

Bogolu Haranath's picture

Couple of other choices for the price of 23i are, NHT C4 and Revel performa F206 :-) .......

Peter-PhonoPhono's picture

After reading the listening report as well as the comments, I could not resist commenting on the PMC Fact. I am dealer in Berlin, Germany and carry PMC for years. The Fact.8 is - in my opinion - a fascinating speaker. As all PMC speakers, the FACT.8 is very natural and - with the wrong amplifier - can sound a bit (too) dry. I cannot judge the Benchmark or Bryston amp, as I don't carry those brands.
I present the Fact.8 with an excellent, well matching amplifier like a Sugden IA-4: this combination sounds breathtaking in any aspect. I can only encourage anyone looking for an elegant, excellent sounding speaker in this price range, to try the PMC FACT.8.

Kal Rubinson's picture

From Jim Austin's review of the Sugden preamp: "As I heard it, the Sugden Masterclass LA-4 was not quite a straight wire with gain: it subtly illuminated the music."

Perhaps that's what the PMC needs.

Bogolu Haranath's picture

Tubes are known to have that 'inner glow' :-) .......

Bogolu Haranath's picture

Measuring the PrimaLuna EVO 400 pre-amp, JA1 said, 'it has second-harmonic distortion signature, which will fatten-up the sound' ........ So, EVO 400 could also, 'illuminate the music ' :-) .......

Peter-PhonoPhono's picture

I agree, a Sugden might not be the most neutral amplifier on earth - but also far away from coloring. A Sugden will make many (most?) speakers sing, which is what most listeners love.
We also use a lot of valve amps as partners for PMC , i.e. EAR Yoshino, Air Tight, Mastersound. Many 'british' amplifiers (Rega, Croft and others) also go well with PMC. All those amps might play a tiny little bit on the sweater side.
I don't think, the Fact.8 is a critical speaker. However, it will immediatedly show wrong system matching (as it should do with this price tag!).

JRT's picture

What this overly flawed loudspeaker really needs is a complete redesign, not just a pairing with a boutique amplifier that cascades another set of sound defects onto the highly flawed electroacoustic transfer function.

Bogolu Haranath's picture

If we add active or passive subwoofer(s), that could help for this model PMC speakers ....... The crossover could be set around 160 Hz with the subwoofer(s) ........That could help in the bass, upper bass and lower midrange regions ........ Of course, that would add to the total cost of the system ..... PMC makes some TL subwoofers, BTW :-) .......

JRT's picture

There are better loudspeakers available at much lower price point, and there are very much better loudspeakers available at similar price point.

I would argue that it would be better to choose something else, regardless any consideration of subwoofers.

And perhaps the money saved by choosing something better at a lower price point might free up some budget to pay for a good low frequency subsystem. For example, you can get an SVS SB16 Ultra powered subwoofer for $2.0k or two for $3.8k. Those are relatively well designed with good performance from a retail product at the price point.

https://www.svsound.com/products/sb16-ultra

https://www.svsound.com/products/dual-sb16-ultra

Bogolu Haranath's picture

Yes ...... Q Concept 500 which I mentioned, see below ....... Another choice is Revel Performa F228Be, $10K, which KR reviewed ...... There may not be a need for subwoofers for the Revels :-) .......

JRT's picture

Modal response of the room around and below Schroeder frequency, more specifically the interference from associated Eigentones, can sometimes be exacerbated by full range loudspeakers with positioning optimized for good performance above the Schroeder frequency.

In more plain English, the locations and positioning good for the spectrum of sound radiation from tweeters and small midwoofers might not be good at the much longer wavelengths of subwoofer frequencies which excite standing waves in the room (room modes) at low frequencies, sub-Schroeder spectrum where that causes very audible interference problems.

That modal response might be improved, the problems ameliorated with use of a well designed separate low frequency subsystem using multiple subwoofers suitably positioned, using suitable processing, maybe using some PSI AVAA C20 active interference sources in room corners, etc.

Bogolu Haranath's picture

Yes ...... We can do it either way ....... Full-range speakers with digital room-correction technology such as Dirac Live, Anthem Room Correction (ARC), Audyssey multi EQ etc can also be utilized :-) .......

Ortofan's picture

... now buy a pair of the Revel Studio2.

Quoting KR:
"What's not to like—indeed, love—about the Revel Ultima Studio2? Almost nothing. I could point to the flimsy trap door and the less-than-overwhelming soundstage spread, though the latter was probably particular to my room. In the areas of lack of coloration, integration across the audioband, dynamic range, imaging, and soundstage depth, the Studio2s were simply outstanding. Including electrostatics that can't approach the SPLs that the Revels handled with aplomb, the Ultima Studio2s imposed less of a fingerprint on the sound than any speaker I have used. Urgently recommended, both to those in the market and to those who simply want to hear how good a loudspeaker can be."

Quoting JA1:
"The Revel Ultima Studio2 offers superb engineering and measured performance for which no apology need be made. It is a worthy successor to the original Ultima Studio, which has been one of my speaker references for the past seven years."

https://www.revelspeakers.com/products/types/floorstanding/Studio2-.html

https://www.stereophile.com/floorloudspeakers/308revel/index.html

https://www.musicdirect.com/speakers/Revel-Studio2-Tower-Speakers

Kal Rubinson's picture

Ortofan wrote: The $12K price of these PMC speakers will now buy a pair of the Revel Studio2.

Yes and, in fact, I bought a pair and a half!

Ortofan's picture

... Victor Kiam level of endorsement, but close enough.

Bogolu Haranath's picture

Not so fast ....... Who knows, KR could buy the Revel speaker company after he retires :-) .......

Kal Rubinson's picture

I retired in May of 2015.

Bogolu Haranath's picture

I meant retiring from reviewing for Stereophile ....... However, we don't want you to retire from reviewing for Stereophile for many many more years :-) ........

Bogolu Haranath's picture

Mr. Kevin Voecks thanks you for your support :-) ........

Kal Rubinson's picture

Yes, he has and I have thanked him for his. :-)

Bogolu Haranath's picture

Another choice for $15k price tag, Yamaha NS-5000 :-) ........

Bogolu Haranath's picture

Adding couple of powered subwoofers from other manufacturers could bring the total price tag to around $15k ....... Then the total set up could produce decent full-range sound :-) ......

Bogolu Haranath's picture

Q Acoustics Concept 500 reviewed by Stereophile, may be a better value for the money at half the price :-) ........

Kal Rubinson's picture

Peter-PhonoPhono wrote: I agree, a Sugden might not be the most neutral amplifier on earth - but also far away from coloring.

Either/or. It is one or the other to some degree.

Bogolu Haranath's picture

Another Sugden model A21-ai integrated amp was reviewed and measured by Stereophile ........

May be two negatives make a positive :-) ........

DA KOOL 1's picture

Hi y'all

I just wondered if any of you will be familair with this vintage speaker and could give me someadvice on their performance.

I'm thinking of buying a pair
#

Roger That's picture

This review basically describes a pair of loudspeakers that perform below what it should, even if their price was 10% what really is.

One can argue that maybe it will sound good on a particular room (maybe the one that the engineer’s used to “tune it”?), but it seems way too flawed to work properly on most rooms.

There are loads of loudspeakers that behave and sound a lot better from a fraction of the price (some were mentioned on the review), and I believe that the Stereophile method of reviewing (subjective performance first, measuring after) usually shows a correlation, or at the very least, helps in understanding what might be the behavior of a specific reviewers room and the loudspeaker itself.

I don’t trust most subjective reviews in isolation because even if the reviewer has very similar sonic tastes as I do, we might get totally different sound performance from the same speakers because the room got too much in the way.
I learned it with my own money (by basically wasting it in the process of bad decisions).

I can now measure my rooms (which leads me to understand their problems) and I strongly feel that John Atkinson measurements are a huge and amazing library of data on loudspeaker performance.

It doesn’t suppress the need of human reviewers (at all), but it goes hand in hand on helping to understand the science behind it and maybe have a greater chance of making informed buying decisions.

I believe that both reviewers were as polite as possible in the way this $12.000 loudspeakers behaved, and all but the seriously distracted reader understood what was presented.

This is also great for the manufacturer if it acknowledges that we’re not longer in a age where real information is scarce, and brings this product (and future ones) back to the drawing board.

I would like to congratulate both Stereophile and Mr. John Atkinson for the amazing contribution on loudspeaker reviewing and testing for all these decades.

Thank You.

John Atkinson's picture
Roger That wrote:
I would like to congratulate both Stereophile and Mr. John Atkinson for the amazing contribution on loudspeaker reviewing and testing for all these decades.

Thank you Roger. I believe that the suite of measurements I have developed over the last 30 years for Stereophile provide good correlation between a loudspeaker's measured performance and its sonic character. These measurements do a good job at revealing coloration, overall balance, low-frequency behavior, and stereo imaging accuracy. However, they won't tell whether a loudspeaker is great or merely good. For that the listening experience is paramount.

John Atkinson
Technical Editor, Stereophile

Bogolu Haranath's picture

JA1's loudspeaker measurements are the gold standard, best in the world ....... Even better than Hi-Fi News measurements, if I'm allowed to say so ...... Thank you JA1 :-) .......

Kal Rubinson's picture

Roger That wrote: I believe that both reviewers were as polite as possible in the way this $12.000 loudspeakers behaved, and all but the seriously distracted reader understood what was presented.

I would like to congratulate both Stereophile and Mr. John Atkinson for the amazing contribution on loudspeaker reviewing and testing for all these decades.

I have no doubt that Stereophile readers understand what was presented as evidenced by their scrupulous analysis (in letters and posts) of what we publish. We have no need to be nasty or snide although the temptation is undeniable.

JA's efforts over the years have been critical. For readers, he has provided not only clear and useful information but, also, an accessible database that allows one to compare products objectively and to see how manufacturers have advanced their their technology over time.

For reviewers (or, at least, this one), the knowledge that JA will be testing and measuring the products that are passed on to him imposes a need to consider "What am I hearing?" in addition to "How does it sound?" That, alone, enforces a deeper appreciation of the product's performance.

Bogolu Haranath's picture

If you look at the FR measurements of DeVore GibbonX, you can find a lot of similarities, especially from 100 Hz and above :-) .......

X