PMC Twenty.21 Bookshelf Speaker Review

[Theriverlethe]

I dont get it? In some local audiophile circles PMC is regarded very very highly.
Is that a herd mentality? Or is that a curve people actually like?

I could see how someone with mild-to-moderate high frequency hearing loss might like them.

 

[Xyrium]

I could see how someone with mild-to-moderate high frequency hearing loss might like them.

As long as those same individuals aren't doing anything in the music recording business! LOL

 

[JohnYang1997]

As long as those same individuals aren't doing anything in the music recording business! LOL

But they do lol

 

[vkvedam]

Wow! Another one bites the dust indeed , never was impressed with their sound in trade shows.

Let's get an ATC SCM series speaker please ‍, I always admired and fancied those.

 

[Xyrium]

But they do lol

I know, it's crazy! And here we are, just focused on the FR plot. Look at the distortion!

So, these are used monitors, perhaps used and abused? Did the previous owner run them through the ringer?

Why am I trying to give these any excuse I can find? LOL

 

[Koeitje]

@amirm if you play them loud and low do you hear weird puffing noise from the port. I had that on my Twenty.22...which I sold (got M106 now).

 

[YSC]

This really looks shameful, kind of audio gd in speaker..

now I think my old KEF X300A isn’t that bad

 

[Dennis Murphy]

Some dude in Baltimore scored some drivers and raw cabinets for a pair of Fact 3 monitors several years ago, along with one actual assembled speaker he borrowed from a friend, and asked me to measure the completed speaker and then try to replicate its response. His friend wouldn't let me check out the stock crossover and trace through the circuit, so all I could do was measure the completed speaker, and then start from scratch by installing and measuring the the drivers in the raw cabinet and importing that data into my design software. This was as close as I could get. The guy has since disappeared and hopefully I won't be called upon to build the crossover and actually listen to the thing.

 

[617]

Some dude in Baltimore scored some drivers and raw cabinets for a pair of Fact 3 monitors several years ago, along with one actual assembled speaker he borrowed from a friend, and asked me to measure the completed speaker and then try to replicate its response. His friend wouldn't let me check out the stock crossover and trace through the circuit, so all I could do was measure the completed speaker, and then start from scratch by installing and measuring the the drivers in the raw cabinet and importing that data into my design software. This was as close as I could get. The guy has since disappeared and hopefully I won't be called upon to build the crossover and actually listen to the thing.
View attachment 71277

Is that just lack of measurement resolution in the bass or are those the transmission line resonances?

 

[LDKTA]

Wow. This is abominable loudspeaker design.

 

[Dennis Murphy]

Is that just lack of measurement resolution in the bass or are those the transmission line resonances?

The peaks at 140 Hz and 80 Hz are room modes. The response below 80 Hz is junk, and above about 300 Hz, it's anechoic. I'm sure there are transmission line resonances as well, but quite frankly the TL wasn't doing enough to produce much of anything.

 

[xykreinov]

Y'know, my Klipsch R-41MP may be really lame, but,

They're not 2 grand lame B)

 

[Thomas Savage]

I feel a apology on behalf of my nation is in order ..,


Sorry to the rest of the world for PMC and us fostering it's underserved reputation,

Sincerely

Great Britain.

 

[Beave]

Soundstage NRC measurements of the PMC twenty.24 show similar problems:

PMC twenty.24 measurements from NRC

 

[Beave]

This link has an image of the cabinet cutaway (see the pics on the top left and click on the pic of the cabinet insides):

PMC twenty.21 cabinet

 

[fredoamigo]

And this is the best example (at least so far) of what happens when buyers fall into the trap of simply thinking

1) It is expensive
2) People say it is good / Professionals use it

And even then it could be avoided by a proper audition, which leads me to

3) People who have poor listening / testing ability yet believe their subjective observations over everything else.
4) Or blindly believing just because it sounds different and it is expensive means it is good.

This is not even the first model of speaker from PMC to behave like this... as the reviews that have been linked in this thread demonstrate. At this point I'm convinced this is intentional design. Intentional as in, even their twenty5 series have their frequency response designed this horribly.

https://pmc-speakers.com/sites/default/files/attachments/twenty5-24 review HiFi Critic Sept 17.pdf

I have seen photos of people using speakers from this line(s) in a desktop setup, toed in and angled up. I cringe. But I don't feel sad nor want to correct them because I've tried and they just go all "don't be like this guy who only believe measurements, your experience is more important"

I completely agree with you, it's also in my opinion intentional. Their design is not an accident this was discussed and decided, these are speakers designed to appeal to the masses, to sell.
In a show room a beginner listener without too much experience will prefer them to a neutral speaker. I suspect b&w to do the same with some of these models ...unfortunately they are not the only ones the list is long !

 

[amirm]

Let's get an ATC SCM series speaker please ‍, I always admired and fancied those.

An ATC SCM19 is here for review.

 

[amirm]

So, these are used monitors, perhaps used and abused? Did the previous owner run them through the ringer?

They physically look brand new.

 

[wwenze]

I gotta confess tho...

At one point in time I was sold on the claims of more bass. "The ATL design enables the speakers to produce higher sound pressure levels and deeper bass extension than is possible with similar sized speakers using either ported or sealed cabinets." https://en.wikipedia.org/wiki/PMC_Ltd.

However measurements don't seem to support that statement a bit. And after noticing normal speakers at USD$200 achieving as much if not greater bass from a normal ported design, and stuffing enough EQ makes them go down to 40Hz in-room, my interest in PMC fell.

 

[Ilkless]

I gotta confess tho...

At one point in time I was sold on the claims of more bass. "The ATL design enables the speakers to produce higher sound pressure levels and deeper bass extension than is possible with similar sized speakers using either ported or sealed cabinets." https://en.wikipedia.org/wiki/PMC_Ltd.

However measurements don't seem to support that statement a bit. And after noticing normal speakers at USD$200 achieving as much if not greater bass from a normal ported design, and stuffing enough EQ makes them go down to 40Hz in-room, my interest in PMC fell.

Moreover, plenty of DIY designs use stuffed TL loading without the massive nulls that plague every PMC design I've ever seen.