Posted on 6 Comments

Mark Audio Pluvia 11 thoughts

I did a couple of different alignments below in WinISD so you could have a look at potential differences.

WinISD is available at here it’s well worth a play with to try and familiarise yourself to what effect varying cabinet parameters does to a speaker.

The Pluvia 11 driver is available in our shop here

Pluvia 7 transfer function in different boxes
The box on the left and the one with the green plot is a 5.5 litre sealed box, f3 about 100hz with a close to ideal box q of .693. The middle one is a ported design that is as close in size to the sealed box as I could get it to try and demonstrate the difference, the tuning and f3 frequency is a bit lower but there is much more energy at the tuning frequency which can be seen in the bump, some people like this and it is how the majority of commercial speakers are tuned as it makes speakers sound like they’ve got more ‘slam’ although it is one of the reasons ported speakers get labelled as ‘one note’. Its also worth noting that although the f3 is lower, by the time we get to f6 both designs produce the same level and the sealed one carries on producing usable level even lower. The third box is closer to the size that is ideal for this driver for a ported box at 15 l, it produces a much flatter response that goes much lower at the expense of size. It is possible to go lower but the size of the port needed goes up exponentially and a bigger box will be needed to accommodate it. There a few other considerations when trying to go lower with a port, firstly port size, you’ve got to be able to fit the port in the darned box! I like square ports, they are easy to build into a box and create less turbulence for the same cross section. You can see from this image the port sizes I used, in the larger box you can use a larger port, probably exiting at the back, running top to bottom. The next plot is of excursion, this driver allows you 7mm one way (peak) of excursion, the plot shows that at a full 45w continuous you’ll need to do something about keeping the lower frequencies out of the driver or use less power to avoid destroying the voice-coil/former, of course real world, in an average room, not many people are hitting 45W continuous!
Pluvia 7 excursion limit in different boxes
There are two other problems created by porting it’s worth being aware of, one is port chuffing. It’s hopefully fairly obvious that the sound created at the port exit sums with the port created at the driver cone and that is what creates the summed FR that results in the lower f3. The air inside the port resonates back and forth like a solid plug of air in the same way  the the driver cone does, this moving back and forth happens at a given speed that ideally we would keep at below about 5% of the speed of sound to avoid the sound of the turbulence becoming audible (chuffing), that is about 17 metres/sec. A larger cross section (wider port) allows us to keep that slower but as the cross section gets bigger we need to make the port longer. The smaller of the 2 boxes is reasonable and probably better than a lot of small speakers out there at 20ish m/s, the bigger box has a wider port at 3cm instead of 2 cm but the bigger box allows a longer port, the result is much slower port velocity which won’t be audible.
Pluvia 7 pot velocity in different boxes
Lastly the ported speaker has much longer group delay than the sealed box which is another reason people describe a slow or one note sound. It’s all about a set of compromises and picking your poison really, good old physics in action!! This only really scratches the surface!
Pluvia 7 group delay in different boxes

6 thoughts on “Mark Audio Pluvia 11 thoughts

  1. Hi…in what is the pluvia range different than the alpair range?..
    I own chr70 and love what I hear, I’d like to upgrade but dunno which Mark audio to choose.. Any suggestions in the listening impression of pluvia and alpair would help my choice.. Thanks

    1. So you’ll find a very similar flavour to the sound whichever way you go. The Alpairs really dig down into the detail whereas the Pluvia can take more of a beating and handle a little more power.

  2. Just stumbled on your website by accident and l am so glad l did! I’m very intrigued with the designs you have on offer. Firstly, some background: I am now in my early 60’s and have built numerous hi fi speakers (mainly of my own design) over the past 45 years. However, It has to be said that most of my early attempts were based on a hit-and-miss foundation. Indeed, they were created by a ‘feel for design’ rather than any scientific measurements. The use of timber ‘off cuts’ l had to hand often dictated the size of the cabinets, while the speaker drive units l chose were the ones l could afford, rather than the ‘exotica’ that l craved for. Nowadays, my designs are much more thought out though. For example, l take advantage of computer software as well as designing and building the speaker crossovers from scratch and l’m in the fortunate position of being able to afford some of the better speaker drivers currently available. Although l admit that good speaker design should be based on available technology, l still feel that there is an ‘hidden art’ in creating that elusive ‘perfect’ hi fi loudspeaker – otherwise how can l explain why some of my earlier attempts in speaker building sounded so darn good? The designs your website has to offer really appeal to me – my own efforts being pretty boring by comparison (either a rectangular ‘infinite baffle’ design or a rectangular ‘bass reflex’ design). I wish you and your new venture well.
    Geoff Crawford,
    North Wales.

    1. Hi Geoff, Good to hear from you, thanks for posting a little about your own speaker journey. I’m lucky to be able to have access to computer modelling during the entire journey I have been on myself. You are right though, there is an art also involved. Getting things almost perfect with the available maths and then tuning by ear will always be a worthwhile process as you have found. Thanks for your comments and I hope I can count you among one of my customer one day?

  3. Hi, I’m planning to build a set of FHXL with the Pluvia Eleven using your flat pack etc for a friend and we are trying to find the running in time of the Pluvia but can’t seem to find it any ware. I ran in my Alpair 12P’s for over 800 hours as required and they sound incredible…
    Can you help us out by shining your light on this matter?
    Cheers, Ingmar Bos

    1. Hi Ingmar,

      The good news is that the Pluvia range are more robust than the Alpair range, that means you don’t have to be quite so careful with your initial level. If you connect them up and leave the drivers running while you build the cabinets and then just use them once you’ve got them fully built. After about 30 hours they’ll sound pretty good and after 100 they’ll be fairly stable.

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