PMC MB2S thoughts appreciated

[Ah4567]

So i've had a chequered history with hifi. 

 

After a pair of Bose 501, which were entirely enjoyable, but not "hi-fi", I started with a pair of Sonique 6.5 and a top end Yamaha amp. High end heavy, but a great entry to hifi.

Graduated to VAF i-93, Arcam amplification, TACT correction, Velodyne sub. Amazing full range sound, though in some ways a touch analytical. All round pretty epic and was super sad to see them go when I left Australia. 

Sold everything , moved to London, and ended up with a pair of KEF LS-50 and an Adam Sub-7 for some years. I enjoyed this, with little expectation of anything more than a small form-factor enjoyable sound experience.

 

All of these gave me listening pleasure. 

 

I then spent some time with a Beosound Stage, which is aesthetically beautiful and fantastic acoustically given the laws of physics, though upon ending up with a real place of my own in Australia again, rapidly graduated back to real sound.

 

My most recent system has been Dynaudio C1-II, Devialet Expert 200, SVS Micro 3000 (crossed over at 40hz, with no crossover on the mains to match their rolloff. SAM generally turned off). I've really enjoyed this. It's been a beautifully warm and enjoyable system.

 

Enter the most recent purchase, somewhat by accident, though I'll take it. 

 

PMC MB2-S, Devialet Expert 200, SVS Micro 3000.

 

My initial thought are: this 20-25000hz speaker is a monstrous lie. I presently have them on the floor, as I need a mate to help me put them on the stands. 

 

Bass response clearly drops off at, by my estimation, 60-70hz. Midrange and treble clarity is literally the best I have ever heard. It's pristine, effortless, and the entire speaker gives the impression that it can keep going FOREVER. Treble is too accentuated. 

 

At present, I've dropped treble by 2db, increased bass by 4db (mild muddiness, but it helps), and kept the hilariously tiny SVS crossed over at 40hz, where it adds a boost where needed, though I suspect it should be up closer to 50hz, which I'll try when I find my SD card reader. 

 

Long story short, these speakers have the most amazing midrange clarity I've ever heard, the most effortless volume, attack, punch...  and guitars/bass which felt stretched through the Dyns are now utterly visceral, within the bounds of my impending eviction. Honestly, sub-bass aside, play some Tool, Rage, Metallica, whatever... holy crap, whatever was missing is THERE. Play dubstep.... add the shoebox sized sub to round out the wub... and it's astonishing, bounds only set by neighbours and probably eventually the ~260W/ch of amplification currently available. Play acoustic/vocals and simply marvel at those midrange drivers.

 

That said, the bass response is immensely disappointing. I feel as though with a MONSTER sub (or two, ideally) crossed over at 50-ish HZ to keep up with them, it would be an endgame setup. 

 

I also do realise on the floor (albeit tilted to achieve 10 degree phase recommendation) is impacting bass definition/muddiness, among other things - I'll fix this shortly - though this will absolutely not increase the clearly missing bass magnitude. I do know it's not ideal for a plethora of reasons, though the overall tonal balance or bass output (if not clarity) is not going to be an order of magnituide different once I get a mate to help me move em.

 

I never intended to use the SVS at any time, though even with the 40hz crossover, it made a fantastic difference.

 

I switched back to the Dyns and was immediately... bored by what seemed like a muddy presentation, though with (utterly ridiculously), dramatically better bass response - at light to moderately high listening volumes. If I turn the PMCs up to concert-level, they're utterly insane.. I'll try a week-long A-B test later, to properly test enjoyment.

 

My immediate feel from these speakers is that they are immensely high definition, low distortion, have absolutely nothing remotely resembling a linear frequency response, and that with some solid EQ, supporting subs (with phase integration), they could be some of the best I've ever heard, capable of utterly astonishing transients across the full range of hearing, albeit imposing and ugly. I suppose my expectation that the 20-25k spec would be linear was perhaps misplaced. Turns out ATL doesn't mean "magic".

 

My next step is to put them on stands, unpack my new Arcam AVM60, and start playing with EQ/ARC/sub integration to get them tonally adjusted to where I want them. Obviously I'll upgrade sub(s) to match as and when. I'm curious as to whether or not an amp upgrade will help - sure a Bryston 14b-SST will drive them louder and with more woofer control, but it's not going to dramatically adjust the tonal balance IMO - opinions appreciated.

 

I'd be really interested to hear other folks experience with these, as I'm partially disappointed, also partially wowed, though by a totally different end of the spectrum to what I expected to be .I fully expect that if I powered them with some 14b-SST power, EQ'd them properly, integrated a pair of subs, I'd have one of the best systems going, capable of incredible detail, while also able to viscerally move my chest as and when I desire. 

 

Any experiences or thoughts are very much appreciated.

 

Cheers

Al

 

 

**edited with accentuation due to verbosity....

 

 

Edited November 21, 2024 by Ah4567

[BugPowderDust]

Can I suggest you try a few things first?

 

1. Get REW and a measurement microphone and measure what frequency response you are actually getting in the room with the sub disabled?

2. move the speakers back and forward to your main listening position and see if the bass improves

 

The MB2S are sensitive enough (91 dB) to not need a ridiculous amplifier. The Devialet is rated to 200W into 6 Ohm and your PMCs are nominally 8ohm so this should still be sufficient for purposes.  The Bryston amps often do get sold with the PMC gear as a bundle so they would be a good match but unlikely to solve the issues you are speaking of.

 

I'd wager a few things are happening:

a - the speakers are fine but you're not used to the sound of pro audio gear which can appear to be leaner in presentation than hifi gear

b - the speakers are in a position that has you at a point in the listening position where bass response is not optimal

c - you're not getting much room gain out of the system as it stands today so repositioning not only the speakers but also your listening position could help

 

Start with the two points at the top and see how you fare. REW is useful as you can visualise what you are hearing and then can make a call as to whether the fix is capable of being done with muscles (moving stuff) or DSP.

[Satanica]

I think you are probably getting some room induced cancellation at some bass frequencies. I also think you should stop using the SVS Micro sub, because there may be phase issues between it and the speakers also causing some cancellation. Once you have just the main speakers sorted, then consider bringing a subwoofer or more back in. As advised above, it would be advantages if you can measure in room at least at the main listening position.

Edited November 22, 2024 by Satanica

[Ah4567]

Thanks both for your comments. To clarify a few points:

 

These are PMC MB2S, 4 ohm nominal. https://pmc-speakers.com/studio/passive/mb2s/. They have a different impedance to the MB2SE, so I'm assuming that there are crossover differences and that the SAM profile phase adjustments may not yield positive results.

 

The Devialet apparently puts out 269W into 4 ohms before clipping, though I'd guess it's not super happy by that point. I was curious about amplifier matching, as apparently some speakers in this family (I'm bundling IB2 in there) have a difficult to drive phase angle curve. If anyone has experience with these specific speakers and can comment, it would be appreciated.

 

Various other measurements online do show a significant rolloff below 40-50hz on similar monitors (IB2 - not too dissimilar and rated at 25-20k, again with variability unspecified) 

 

I've owned studio monitors before, a well as VAF i-93, which have a quite lean presentation, flat +-1.2db from 20-20k, so I do trust what my ears are telling me, though certainly a comparison with the Dynaudios is unfair. I also ran some test tones and while output was present below 40hz, it was significantly attenuated.

I did plenty of testing both with and without the SVS - I was primarily aiming not to use it, though added it for laughs and it did fill in the lower octave surprisingly well. They're currently positioned quite close to the walls, so should have reasonable room gain. I have moved them around and listened from different positions.

 

I'm not unhappy with the speakers (I'm actually really happy with the midrange in particular), though it looks like they'll need a little care put into getting the most out of them. 

I'll position them properly (you're not wrong about needing muscles to move these! I very nearly got them up on the stands, before deciding my back is perhaps not as young as it used to be), bust out the mic, and run some sweeps. Then there's the EQ option, which may cause the Devialet to run out of steam

 

Edited November 22, 2024 by Ah4567

[Hertzgeek]

From what I have heard with the PMC range Devialet pairs very well with them. Even more so when SAM is engaged.

 

The 200 is not small but not big either. I have the 120 paired with SF Olympicas. They absolutely crank. These are phenomenal speakers and I have only heard great things about them especially in the MIDs as you have mentioned. I would definitely be using the stands they come with. 

[blakey72]

Yeah There's certainly nothing wrong with those speakers producing bass, there's another issue there. It 'could ' be a current issue as those woofers can be hungry. 

 

As @BugPowderDust said it could very well be a positioning/room issue also and that's where I'd start. Just because one speaker worked in a certain position doesn't mean another will. 

 

Stupid question but you did check speaker cable polarity?

[Ah4567]

Ahaha yes, I definitely checked polarity. I'll give SAM a go when I've dug up my SD card reader and will back it up with some measurements. I don't hold out too much hope for SAM though, given that there's only a profile for the MB2-SE, which I assume will likely have a different phase profile given the impedance difference means there's something different in the crossover/driver topology (even if frequency response remains similar, perhaps), in which case SAM would likely make a mess of the sound.

 

It's not so much that there's not much bass, and the bass definition is superb, with midbass guitar and drums coming through viscerally, but it's a pretty significant rolloff in the lower octave in particular, along with a pretty active top end, which may just need a bit of EQ to suit my taste at lower levels. Turned up to "I really didn't want to meet VicPol today" levels, it's like being at a concert with Meyer Sound, but better.

 

I've read a few threads online that suggest the PMC measurements are pretty all over the place and it had occurred to me that perhaps they're voiced for mastering, while being exceptionally detailed and with low distortion, to accentuate areas that need attention, rather than to be truly flat; which is fine, as the top end can be trimmed a little, but the lack of bottom octave presence was surprising to me. Perhaps it's more a case of overblown expectations regarding bass slam. 

 

I'll check out positioning and will come back with some measurements... 

 

 

 

Edited November 22, 2024 by Ah4567

[Hertzgeek]

A pair of REL T9s will certainly fix bass. Or if budget allows a set of JL Audios... Bass shall never be a problem then

[Satanica]

How far are sitting away from the speakers? 

[Ah4567]

Currently around 2.5M, which I understand to be ideal midfield listening range. I tried different positions though. 

 

I'd think a pair of the better end of SVS, or JL-Audio would be ideal

[blakey72]

How long have you had these speakers? Pre-loved I'm guessing. It sounds stupid but it could be a mix of position and that you just aren't quite used to the sound of PMC. They are very very accurate and will give exactly what's on the recording. 

 

You can't really compare the to Dyn's or any other speaker. They are transmission line too so the bass is very fast and accurate. 

 

Not saying this is what is the problem or your mind is playing tricks just be aware. Thinking back (I've had mine many years) I kind of thought a similar thing I think.

 

Then after a while I 'got it'. Especially compared to my Dyn's (we might have similar tastes in speakers haha).

[blakey72]

And by no means am I saying you have bad hearing or 'your ears are painted on', just trying to throw as many suggestions as I can think of.........Since I also have PMC's but baby's compared to yours haha.

[Ah4567]

I've had them about 3 days! I bought them used from a studio. Been playing with them quite extensively. No stress at all - I appreciate the perspective. I'll pay "fast and accurate", though I'm still thinking there's bottom octave rolloff. 

 

I just found it interesting that the Dyns can energise the room with bass, but the PMCs can't at low to mid volumes. I think the positioning, EQ, and possibly amplifier are the areas I'll explore first. 

 

We may have similar tastes! Although I do find it interesting, from both of our perspectives, that we can enjoy speakers that are so remarkably different as the Dyn/PMC sound. I don't think I want to sell the Dyns, as they are beautiful to listen to, though the PMCs offer an entirely different dimension of clarity and scale.

 

Edited November 22, 2024 by Ah4567

[blakey72]

@Ah4567 You are spot on. The Dyn's offer a very easy to listen to, kind of laid back presentation. A Dynaudio sound! The PMC's offer something totally different. The offer the recording, nothing more, nothing less. If the recording is lacking bass/treble that's exactly what you will hear. It's it's a bad recording well you'll know. If it's a great recording......You'll think you've died and.......

 

There's just no colouration/slant/bias whatever. I LOVE listening to my PMC's however I don't always. I also listen to my Dynaudio's as well as my Focal's. They are all different beasts and you get to know them and what sounds best on them. I had a break from the PMC's for 6 months and only brought them back into the system the other day.

 

My jaw dropped when I heard the first song! So good but not all the time is how I roll. Variety is the spice of life haha.

 

There is probably some bottom end rolloff and it will be found...No don't sell your Dyn's!! (unless you'll be sleeping in the doghouse if you don't)

[maximus]

I heard the MBSE recently and that speaker left me speechless. I played Trent Moller 'The Last Resort', it's a bass heavy album. Apart from being engulfed by that incredible midrange, the bass output was prodigious, hard hitting, I don't think the specs lie, 20HZ acheived, no subs in the picture.

Get the speakers off the floor and onto stands asap. I use a Bryston 4B3 in my humble setup 'PMC 24i's', the bass is astonishing from a 2 way, never heard anything like it,  that's why I'm confused with the Ops situation.

Try an amplifier with a bit more heft, ie Bryston/Vitus/Gryphon, definitely make a difference. 

[maximus]

@Ah4567 The Specs on the MB2S and MB2SE are identical 8ohm 91db, same tweeter, mid range and transmission line length.

The 'SE' stands for special edition, inclusive of an array of timber finishes. Yours being 'S' is only offered in black finish. It's essentially the same speaker.

[Satanica]

19 hours ago, Ah4567 said:

I've had them about 3 days! I bought them used from a studio. Been playing with them quite extensively. No stress at all - I appreciate the perspective. I'll pay "fast and accurate", though I'm still thinking there's bottom octave rolloff. 

 

I just found it interesting that the Dyns can energise the room with bass, but the PMCs can't at low to mid volumes. I think the positioning, EQ, and possibly amplifier are the areas I'll explore first. 

 

We may have similar tastes! Although I do find it interesting, from both of our perspectives, that we can enjoy speakers that are so remarkably different as the Dyn/PMC sound. I don't think I want to sell the Dyns, as they are beautiful to listen to, though the PMCs offer an entirely different dimension of clarity and scale.

 

If you've measured them with them rolloing off in room at about 40Hz, then indeed they are missing the last octave and that is non-perfect colouration. No speaker is perfect and this speaker is not perfect, despite the razzmatazz. I think your plan of larger subs is a good one and I recommend you cross them over in the 60-80Hz range and then you will have a 4 way system. If crossing them over is part of your plan, have you thought how you will do this?

[Ah4567]

I’m a little uncertain re impedance tbh. The actual brochure for MB2S clearly specifies 4ohm. Google it if you’re interested, as stereo net won’t let me link it. I’ll buy a multimeter to check tbh. I know measured will be different to nominal, but it’ll give an indication.

 

I’ve also bought an Anthem AVM60, which should provide all the crossover, phase adjustment, time alignment, room correction I need. In the past I haven’t enjoyed room correction above 500hz, as it’s sucked the life out of the sound, though perhaps a PEQ for taste at low and high frequencies + ARC for sub crossover/phase integration. 
 

I found with the Devialet and Dyns, allowing the natural rolloff of the Dyns, with SAM off or largely off (still with phase adjustment), and the sub coming in at 40hz, has been a great combo. I’ll do some trial and error with the PMCs.

 

I know the AVM 60 isn’t the “best” in terms of pure hifi, but it should give me the control I need and if I need to go more purist later, I will. Still an open question to my mind about amp quality/heft needed.. 

Edited November 23, 2024 by Ah4567

[Satanica]

38 minutes ago, Ah4567 said:

I found with the Devialet and Dyns, allowing the natural rolloff of the Dyns, with SAM off or largely off (still with phase adjustment), and the sub coming in at 40hz, has been a great combo. I’ll do some trial and error with the PMCs.

In my opinion, effectively crossing over subs that low (40) is a bit too low to get all of the benefits larger subwoofers. For electronic music with a lot of relative content in the 20-40Hz octave it would work well. But with most types of music, there is much more content in the 60-100Hz range. Anyway, totally up to you.

[Ah4567]

With the Dyns, given they have a really robust bottom end, much more so than the PMC, albeit with severely constrained relative compression free output, it has worked well at the moderate-high levels I’ve listened at (I’m in a large apartment right now… buying a house in Melb soon), with no crossover on the mains. Absolutely it would work well crossed over higher if I wanted increased maximum output.

 

with the PMCs, almost counterintuitively, I think it would work well higher up. I’ll experiment with the REL philosophy of tuning the sub crossover to suit the natural rolloff of the speakers, by my estimation (to be validated with measurements) around 50-60hz, or otherwise perhaps higher, with a matching crossover on the mains. That would result in a system with incredible distortion free sustained output capabiiity and the Anthem should allow appropriate level/crossover/time/phase integration to make it happen well.

 

one element of the Dyns somewhat lacking was what seemed to be a real dip in the upper midbass range that prevented guitars/bass/drums from hitting viscerally. Given the laws of physics, I think there’s limited ability to correct for it too much without introducing distortion. The PMCs have none of that.

 

I’ve got some tinkering to do 

[Bass13]

@Ah4567

 

Congratulations on your PMC's

The only way to know for sure..... to see what's going on with the frequency response in your room with your speakers, is to take measurements, and work from there.

Enjoy your journey....

 

[sir sanders zingmore]

I’ve heard the MB2SE version and they did not lack bass. It was tight and accurate though, and this can sometimes be heard as “bass shy” until you get used to it. 
As others have suggested, measure them and try positioning differently and certainly get them up on those stands. 
 

It might also be worth hooking them up to a beefy high current amp (but only after you’ve got the positioning right, if they are creating a null then pumping more power won’t really help ). 

[Ah4567]

Put them on stands: immense difference in total bass output. Everything is tightened up. Still a little less in sub bass, but nothing a sub or two won’t fix. 
 

 

[Hertzgeek]

4 hours ago, Ah4567 said:

Put them on stands: immense difference in total bass output. Everything is tightened up. Still a little less in sub bass, but nothing a sub or two won’t fix. 
 

 

Are they the stands that the speakers came out with originally? Or just a generic speaker stand to try it out?

[Ah4567]

With the genuine PMC studio stands. They’re properly excellent. To quote my mate who helped me lift them up “that’s the best sound I have ever heard”

 

I think with a few incremental improvements along the lines of the above - amp, measurements/eq, subs, it’ll work out quite well.

 

hardest part will be aesthetic integration…