|PMS, built by Andy
Copyright 2011 © Troels Gravesen
Well, finally the speakers are finished. It definitely took a lot of time. The part that most concerns me is how the cabinets were made since they are not the typical square boxes. I had to glue together multiple narrow panels together to make the curved front baffles. I was careful to fill any open gaps with silicon since a leaky cabinets will make the bass sounds loose and muddy. The back panels are slightly different from yours so to make things a bit easier to make.
Being a complete amateur in wood works I really had no idea how it would turn out. There were a few moments frustration where I thought I had to start over but I figured I had to improvise and find way to move ahead. Making all the pieces aligned and making sure everything is sealed up given all the different pieces that needed to put together were pretty difficult. You can't really make one cut and everything will fit. You kind of have to adjust as you go along. But thankfully everything worked out at the end.
The speakers sound really good -- very natural, balance but with lots of details so you could hear into the recording -- not an easy combination. There are several musical passages with a very faint backing vocal that I was not able to hear before but with the PMS, I actually notice it for the first time. Considering the relatively inexpensive cost of the drivers, it's amazing the amount of hi-end you could get from such a modest investment (of course not including breaking one's back making the cabinets :-)).
The speakers are pretty efficient and easy to drive. I have a pair of 50W tube mono blocks and they can drive them at pretty high level with very good bass control. I think I'll try them with a 140W solid state next.
My port length is about 14.5cm which is a little longer than yours but the bass is pretty deep already and I don't think I need to shorten
the port any further. I prefer the bass a bit tight. My mid range cab is not ported since it's pretty good as it is and I don't want to make any further changes that may adversely affect other areas. Since I don't know what improvement form this so I think I am going to keep it the way it is now. Drilling holes on a finished cabinet scares me a bit.
My cabinets have very little stuffings. I got a small amount of egg crate foam on top and just a small bit at the bottom and a thin piece of foam
at the back of the drivers and that is about it. I am not sure what your preferences in term of cabinet stuffings, but I always prefer to have as
small amount as possible. I feel that stuffings usually over-damp the sound and making the sound decays less natural. A balance decay time I think is what people prefer to as "air around the instrument". It makes the "ringing" sounds nice and natural. With less stuffings sometimes
the bass could be a touch muddy (though not in this case) but I would make that slight trade off.
You discussed in you website that this type of 3way design is more or less a classical approach and I think they work really well with a tweeter + midrange + bass configuration. The speakers have most of what one would look: good bass extension, good mid range presence, good integration among all the drivers (and the xover probably has a lot to do with this).
I would like to sincerely thank you for making the design available so people like me could have a chance to enjoy this hobby as well.
Your website is one of the most comprehensive source of speaker design I have found on the web and I had learned a lot from you.