Living with (the) PMt

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Hi Forum.

I'd like to share my listening impressions of a pair of speakers designed (around a flared port available from Jaycar!) and built by Rabbitz. There were two reference speakers used when designing the PMt's, the Yamaha NS10M studio monitor and B&W DM303 so these weren't just knocked up with a 'hope for the best' attitude. I'll let Rabbitz explain the name ;)

The speaker is a 12L ported design with a 1" XLS 810653 tweeter and 5" HDS 850488 mid/woofer, both from Peerless. Built from 16mm MDF using minimal damping material and a series xo with only 3 components. Impedance is 6 Ohms and sensitivity is 89dB.

I've only had a chance to compare the PMt's to Dali 1A's and KEF Reference 103.3's. That doesn't sound like a big deal but the KEF's were originally over $2k new. Comparing approx $450AUD PMt's to speakers from a respected manufacturer really seems unfair, but it's not.

Firstly the Dalis, they were slautered in all respects. That was easy!

The KEF's on the other hand are twice as old but a much more refined speaker. A 3-way design in a 29L 'bookshelf' with a sealed downward firing woofer at the base of the cabinet. With that they were bested in all but the bottom end when the KEF 'active eq' was set to it's lowest setting which allows the woofer to reach down to 40Hz - the cutoff frequency is 50Hz by default. Not much is given away to the KEF's bottom end though so consider the PMt's go down to 'only' 57Hz it's quite a feat!

The bass of the PMt's is suprisingly full. To elaborate on this and the all round performance is easy. On songs that begin with plenty of bass you wonder if you'll ever be able to make out the mid and high frequencies when they kick in. At times you even start to doubt. Then a vocalist begins to sing and any doubt you had is dispelled immediately as you get lost in the music. That's the ticket!

Right, so the bass is great... the mids are better. Emotions are easily stirred with the right recordings be it foot tapping, teary eyes or the hairs standing up on the back of your neck. Male and female vocals are equally beautiful. I've read numerous times that female vocals sound better than male vocals on this or that speaker. Personally I think that's a bit silly and it's simply as a majority people prefer the sweetness of the female voice just as the majority prefer to look at the female body. I couldn't honestly say either sounds better through the PMt, they both sound awesome. There seems to be just the right amount of everything.

Dynamics are so good I've re-learnt my CD collection on that attribute alone. More than once I was scared off the couch! Detail, soundstaging, attack and so on are all there in just the right amounts to give you a great experience. Naturally, correctly setting them up yields the best results. The soundstage can be magic :D

I'll wrap up now. There's plenty more to say but there's probably no one reading anymore. A final point I'd like to make is this is DIY, I'll probably make some more speakers at some point. Whether they're better sounding or not is something to be determined but it'll take some serious work and a lot more money. With this speaker I have something I could happily live with for years and quite probably will. If/when a new speaker is built with the aim of besting them I'm confident I've an excellent reference point to judge from.

Components used with the PMt's are a LM3875 based amp with a 23 step passive pre and a Marantz CD67mkII CD player. Nothing fancy but they work and play together really well. A better CD player would make them sing even sweeter.

Many thanks to Peter (Rabbitz) for sharing his design with myself and the DIY community. Many thanks again to Peter (yeah same one) for building a pair of beautiful cabinets (see photo) and sending them to me ~500km's away! That's a long story, I'm not going there :)

Thanks mate, you truly are a gem of the DIY community.

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A reply.....

Thanks for the kind words as it's always an anxious moment when someone builds one of your designs. A large leap of faith on your part as there is considerable money and time involved.

Had to use that port (like it) as it was front firing so went away from my normal PVC pipe and the PMt name shall remain a secret so not to offend any of the ladies ;)

I'd like to comment on a few things such as it was important to have a reference when designing and building. Both speakers used are well regarded in their field, the NS10M in the studio (not a Hi Fi speaker) as near field monitor, but excel in their mids (top end a bit peaky), the DM303 a budget 2-way that was a EISA speaker of the year so was the one to beat. In the end the B&W sounded muffled and restrained when compared to these so the design goals were accomplished.

The design is quite conventional but 2 things made it work. the superb Peerless 850488 which is quite amazing and it's a shame it's being discontinued and hopefully the 830860 and 830873 will have the same qualities. The series xo makes them sing and was chosen after much testing. I have to thank Andy Graddon for his great series xo spreadsheet which gives a good starting point. The original design which was posted here previously was eventually changed after prolonged use. It's easy to get caught with a crossover when testing as it can sound so exciting but eventually doesn't cut it in long listening sessions so the final xo is more laid back.

These speakers do not have a completely flat response but have been tailored to sound musical and pleasant on the ear and I believe that's what's important in the end..... have to be enjoyable and not sterile. Don't always trust or believe the response the software is telling you as I've found in the majority of cases that the so called optimum suggested is not the best.

Production run of 3 sets with 1.5 sets to go before production ceases :)

Now off to the next project...... to design a real el cheapo that sounds good.
 
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