PMC twenty.22

mhardy6647

What Hi-Fi? (who are usually pretty responsible reviewers) liked these quite a bit, saying:

Performance
Tonally, the speakers sound a little lean and immensely taut. Some may prefer a more relaxing presentation, but it would be very hard to find such leading edge definition and speed any other way.

The 22 may be medium-sized standmounters – standing 41cm high – but the bass weight and power they produce is impressive.

This low frequency performance is agile enough to integrate well with the explicit midrange and leads to a really cohesive overall performance.

These PMC speakers do it all. They have the scale and power to do justice to Tchaikovsky's 1812 Overture in full flow and the tonal balance to render individual instruments convincingly.

They'll also deliver intimate music such as Bon Iver's Michicant with a pleasing amount of finesse. Their detail resolution and way with low level dynamics is as good as anything we've heard at this price level.

https://www.whathifi.com/pmc/twenty-22/review

Interestingly, of their little brother (the 21), they said:

Get it all right and the 21s deliver a huge, beautifully layered image.

It also helps to turn the volume up. Now we’re not saying the Twenty 21s require party levels of volume to shine, but there’s a marked difference in character between the PMCs playing at late-night whisper levels and what we would consider normal listening levels.

The speakers gain notably in bass presence and authority, and dynamics grow impressively. All speakers alter character to a certain degree with volume change, but with these monitors the effect is more pronounced than normal.

The 21s, once we’ve fine-tuned their placement, now sound special for the money, delivering a solid, well-integrated sound of impressive scale and power. Used this way it’s hard to believe such a grown-up sound can be had from speakers that barely stand 33cm high...

https://www.whathifi.com/pmc/twenty-21/review

Full disclosure, and FWIW, I am a big fan of TL and similar loading schemes (e.g., TQWT) for high quality bass.

Some of my very favorite loudspeakers evah (especially in terms of smaller ones, like the IMF SuperCompact II) are TLs.

joecoulson

mhardy6647 wrote: »

tonyb wrote: »

Lack of bass ?? Hard to believe for a fairly efficient 8 ohm speaker. What are you driving these with ?

FWIW: If they're brand new, and he's talking about pretty low listening levels, it seems entirely plausible to me -- even for TLs.

EDIT: Derp. Sez they're 'used from eBAY' in the OP.

Used but apparently less than 10 hours played if the seller was telling the truth.

halo

tonyb wrote: »

Front port vs rear port.....now that might have a good chunk of why the bass is a bit weaker. Agreed.

Not really a "port" with the transmission line enclosure; at least that's how I understood it when I had the Von Schweikert VR's and the InnerSound Eros Mk II's.

mhardy6647

joecoulson wrote: »

mhardy6647 wrote: »

tonyb wrote: »

Lack of bass ?? Hard to believe for a fairly efficient 8 ohm speaker. What are you driving these with ?

FWIW: If they're brand new, and he's talking about pretty low listening levels, it seems entirely plausible to me -- even for TLs.

EDIT: Derp. Sez they're 'used from eBAY' in the OP.

Used but apparently less than 10 hours played if the seller was telling the truth.

ahh... OK. Seems like modern suspensions tend to take many hours to break in... which is why those ELACs are still being used upstairs

Tony M

I'm wondering why the transmission lines are stuffed heavily on some designs.

It looks like the PMCs are stuffed so much, how can the bass waves travel through?

mhardy6647

Tony M wrote: »

I'm wondering why the transmission lines are stuffed heavily on some designs.

It looks like the PMCs are stuffed so much, how can the bass waves travel through?

It's exactly the opposite, as I understand it... I think one of the main reasons for the stuffing is to minimize the MR and HF from squirting out of the TL 'vent'

I will also say that stuffing a TL -- or a TQWT, for that matter -- is something of an art.

joecoulson

mhardy6647 wrote: »

Seems like modern suspensions tend to take many hours to break in... which is why those ELACs are still being used upstairs

Yep. Mine are just starting to loosen up good. They absolutely shake the house now. Amazing drivers on the Adantes.

FTGV

Great lookin speakers. PMC make a quality product, many of their speakers are used for monitoring in music and film scoring studio's. In my collection I have a pair of the older model TB2's and my own DIY clones of the little DB1's.
At least with their smaller speakers the actual bass loading is really a hybrid of a trans line and bass reflex. The small box, short line results in a bass tuning frequency higher than a typical transmission line.
The damping material(foam) in the line results in a more shallow bass roll off than what would occur with a typical ported design. Thus in theory extending the usable bass response. To me the smaller PMC's that I have heard ,the bass seamed rather lean sounding .Very similar to an over damped sealed box. The larger PMC's I have heard not surprisingly had deeper bass facilitated by their longer line lengths. They all sounded quite good and had excellent midrange.

Clipdat

Thanks for all the comments and people jumping in with ideas and attempting to help me figure out what's going on with these, I sincerely appreciate it.

I'm probably going to get eaten alive for this, but here's a picture of how the speakers are sitting in the 12.5'Lx10'W room:



Keep in mind, this room is a bedroom first that I've shoehorned a stereo setup into. I realize the placement is far from ideal. The height of the dresser is 55" and they are 3' apart. I'm about 9ft from them in the listening position, with my head at roughly at 45".

I had the 703s on acoustic pads that were angled down pointing the tweeter at my listening spot on the bed. I tried the same with the PMCs, but because they are angled back, this resulted in the tweeter/front simply being at a 90 degree angle. I removed them today just to see if it would affect the bass output, it did not.



I tried them for 6 hours today with the Bryston ST 3B and then switched over to the Dayens Monoblocks. Performance was about the same in terms of bass. Maybe a smidge more with the Dayens. With both amps, I have to really crank it up to 80-85db or so before the bass "matches" with what's coming out of the tweeter.

I'm going to keep logging hours on them and hopefully once I hit 50+ they'll have more bass presence at the lower 60-75db range I listen at.

Tony M

Thanks for the pic. Drew.

I owned a set of Nakamichi table speakers and it's matching stereo unit. It was small and EXPENSIVE when new but I got it from somewhere...

Well the speakers had a slot in their bottoms also and when I put them on a shelf or table...WOW...the bass increased 100 fold. Maybe no slot but just had to sit on a reflective surface in front of them. The bass was magical I tell ya … but there was NO bass without the reflection.

I'm wondering if you push them back, would that help direct the bass waves toward you in an amplified technique like that old system I once owned?

I'll get the model number and pic asap. Here it is. "Sound Space one".
https://www.canuckaudiomart.com/details/649082012-nakamichi_soundspace_1_stereo_system/images/629867/

It was small but MIGHTY.

Clipdat

It's possible that they are more sensitive to placement than the 703s. However, I will say that despite the less than ideal placement, speaking in terms of the treble and midrange performance, they have a completely different presentation than the 703s. The treble and upper midrange energy is much more coherent and seamless - more like a fast wall of sound and less directional like you can hear the sounds coming from each speaker as was the case sometimes when listening to the 703s. Basically there's lot more detail to get lost in and enjoy, but without it being harsh at all.

Voices sound crazy good, as does well recorded solo piano. You can actually hear the strike and decay of the key, the note itself, and the wood of the piano resonating. A lot of other speakers gloss over these finer details with piano I think. Very impressive midrange and treble from these PMCs.

If the bass comes around to what the 703s were giving me at my usual listening levels these will be keepers. I hope that they just require a very lengthy break-in process which I plan to give them. I'd really like to give these a fair 50-100 hours before I make a final judgement on them.

FTGV

Well you may find the bottom end fill out some after the woofers suspension's loosen up, but the articulate but lean bass seems to be a family trait with the smaller PMC's. The generally great response from the mid bass on up make them excellent candidates for the addition of a good musical subwoofer,or better yet two.

Tony M

I'm going to go read those links you gave me now.

Sounds like what I heard with some little Totems. Lack of bass but oh man were they putting out clear sound and seemingly from a space around the speakers in a LARGE way. Super detailed. Jaw dropping it was. I just didn't have the cash to get them...but I'll never forget that sound-field and clarity.

I've learned high quality tweeters and high quality midranges/mid-woofers help make speakers what they are! PSB is another that comes to mind.

mhardy6647

Just speculatin' here, but I am thinking that @Clipdat'd like the sound of the vintage IMF monitors. Not small though (other than the Compacts and SuperCompacts).

joecoulson

Yeah those will fit nicely on that dresser ...

mhardy6647

joecoulson wrote: »

Yeah those will fit nicely on that dresser ...

The would be a challenge, yes.
Well, there's always the sideways option, you know?

joecoulson

Lol. They look like they are bigger than the dresser itself!

mhardy6647

There is/was a photo somewhere on these forums of someone who had, I dunno, some big Polk SDAs (or other Polks...) mounted sideways on the wall up near the ceiling.

I cannot find it though.

Unsurprisingly, the image above is from another certain hifi forum

Yeah, I do understand the placement constraints.
Unfortunately, Hoffman's Iron Law plays a part in the solution
There's always DSP (perhaps, more to the point EQ... or... gahhh... tone controls).

Where's that loudness button?

mhardy6647

joecoulson wrote: »

Lol. They look like they are bigger than the dresser itself!

Upon reflection: I guess maybe you could put drawers in 'em and they could do double duty

Sorry, @Clipdat -- I'll stop now.

msg

Really strange. Just did a little quick reading on these after seeing the note about being transmission line design? Interesting. TL speakers are supposed to put out lots of bass then, yeah?

I may have missed this, so, apologies if it's already been posed, but could there possibly one driver out of phase? I've heard about this happening at the factory sometimes, incorrectly wired.


Obvious cable check for the third or fifteenth time.

Very carefully remove the woofer and binding post plate and have a look to see that both speakers match?
(I'm always really wary of the screwdriver skipping off and stabbing a cone, so I try to guide the tip of the screwdriver pinched between my fingers the whole time, keeping it seated in the screw head, and taking my time. Yes, I destroyed a surround once. Jussst once.)

This has to be something simple, and doesn't seem likely it's a break-in issue for them to be so devoid of bass. These things have specs rivaling the numbers on the 703s down to 40Hz. They should have some fairly respectable bottom end.


As a quick test, you could just try reversing the speaker cables on one speaker and see if you get bass in the room?

stangman67

This may not be useful but I’m wondering your living situation? Is there any place else the 2 channel setup can go? I just feel like you are way under utilizing some very very high end equipment due to the setup constraints. You could throw 30-40k of equipment in that configuration and not be happy.

Getting rid of that dresser even and throwing up some stands would be exponentially better. Im sure if this was easy you would have already done it, but that’s the best improvement you can make.

Tony M

I completely forgot a woofer being out of phase! GOOD reasoning.

That absolutely kills bass in a room.

I know from experience. I still own a set of RT55s because of this phenomenon. A man returned them saying they didn't compare to Bose 301s. I know what happened.

Yea, maybe someone at the factory got the PMC woofers wires mixed...But...

Drew said they open up with bass when he turns the volume up. Out of phase woofers would still be lacking at all volumes wouldn't they?

stangman67

My experience with the 703’s certainly seem to validate what Derek said. They are absolutely midbass heavy and while that makes them (IMO) a very fun listen, it certainly probably also explains that your perception of the PMCs are that they are weak in the bass regions. After seeing you grab the PMCs and doing some reading, I would love to get my hands on a set eventually

msg

Tony M wrote: »

I completely forgot a woofer being out of phase! GOOD reasoning.

That absolutely kills bass in a room.

I know from experience. I still own a set of RT55s because of this phenomenon. A man returned them saying they didn't compare to Bose 301s. I know what happened.

Yea, maybe someone at the factory got the PMC woofers wires mixed...But...

Drew said they open up with bass when he turns the volume up. Out of phase woofers would still be lacking at all volumes wouldn't they?

I think there's a possibility you might end up with "almost bass", and not complete cancellation. I'd suspect that the room and speaker placement may factor in to the amount of cancellation, as well? I don't have much experience here, so I'm not sure. Just another box to check off to rule out the obvious-es.

mhardy6647

A big TL can produce phenomenal bass -- a small TL can produce remarkable bass for the size of the enclosure... but as always... there's no replacement for displacement.

GlennDog

mhardy6647 wrote: »

A big TL can produce phenomenal bass . . .
there's no replacement for displacement.

Indeed, doc

These 2 way TLs produce copiious amount of LF, however the rabbit hole forced me to shore-up the dungeons with a Rythmik ... I’m think about a 2nd sub

Room limitations have them about 12 inches away from the rear wall
Had I actually been cognizant during the purchase phase, I would’ve had Jim Salk front port them

FTGV

DSkip wrote: »

The PMC are designed as true monitors...

Yes. It appears they were going for an articulate detailed bass/mid bass instead of thump and boom. With their smaller monitors they could have bumped up the bottom end using the obligatory bass reflex loading used most often with small speakers.
Another big advantage is the damping material in the line serves to reduce strong internal reflections that can be re radiated by the woofer and colour the midrange. All the PMC's I have heard exhibited a very natural clean sounding mid band. The larger models I have heard had the deep, tight bass one would expect of a good trans line.

As for a woofer being out of phase there would be other sonic issues than a just a lack of bass. There would be no central stereo image and it would sound strange, having a distant overly spacious character to it. It would be obvious.

FTGV

Nice speakers GDog. I wish I had the budget for a pair of those RAAL ribbons.

Clipdat

Thanks all for the continued discussion about the speaker's performance attributes, and also my room setup and unfortunate placement options.

In terms of setting it up in a different room, the only other room that would potentially work has this monstrosity in it:



Going back to the 703s for a minute, they do have a slightly accented midbass, but they also have a lot more bass response in general at lower volumes vs the PMCs, at least in my room. I get that different speaker designs will have different levels and types of bass response. However, it just seems that with the PMCs at the lower listening levels that I tend to listen at such as 60-75db, there is just not enough bass to equally match the treble and midrange, as compared to what the 703s were giving me at those same levels. I believe this must be due to the rear ported design of the 703s and how they were only 7" from the front wall. The PMCs are in the same spot very close to the front wall. I do my listening about a foot or so off the back wall.

If I crank the PMCs up to 75-85db they start kicking out amazing sound and the bass begins to more accurately match the level of sound coming from the treble/mid. Maybe they're just voiced/designed to play at these higher levels since a lot of people like to listen loud. However, it's not really realistic for me to listen at this level (especially for extended amounts of time) since I live in an apartment.

They do have a lot of nice characteristics in terms of their treble and midrange performance. It's really no contest vs. the 703s in that regard. The PMCs are much more clear and detailed, without being harsh. It just seems like in general they are capable of resolving the music on a much higher level than the 703s.

Lastly, I've been doing the majority of my bass testing using drum n bass and other types of electronic music. It's possible that these genres are simply not the PMC's forte. While the 703s seemed to do a good job with all types of music, I'm starting to think that due to the way the PMCs handle bass, they're probably more suitable for "real music" and accurately resolving voices, instruments, etc. and maybe not so great for electronic music.

Back to the break-in aspect, I'm going to have to assume they have 10 hours or less on them, so yeah I would like to give them a fair shot to try to get those woofers loosened up so hopefully they get a little more bassey at lower levels.

I mean if I crank up some basslines like the 2:55 breakdown here: https://www.youtube.com/watch?v=YJoBt49oEWA
to like 80db, I can see the bass sinewaves on my db meter and see the woofers moving and kicking out bass. So I feel like they are "capable" of reproducing these low bass notes, but just don't do so until they have a lot of juice/power behind them.

EndersShadow

Sexy KRK's!

They are a set of speakers I'd love to own for my loft someday. Get the Rokit 8's and paired with my MicroPro I'd be done... but where's the fun in being "done"