Open Baffle Phy HP KM 30 SAG update


Well, I finally got around to putting the PHY drivers in prototype baffles. I used 1/2" Birch plywood baffles that measure 45" X 27 3/4". I offset the drivers in the baffles.

When I first fired the speakers up I was disappointed, but I realized they needed to be broken in. My *heavily modified* Newform Research 645's were easily superior to what I was hearing from the Phy's.

I put a bass-heavy CD on repeat and began the burn-in process. The first 10 hours were depressing. The soundstage was flat, congested and had no air. There was a lower-midrange hump that was annoying. Even though the drivers were new, I was hoping for more.

Well, by the time the PHY's reached 30 hours, all of my fears vanished. I am stunned at how good these things sound. They have crushed my Newforms in every respect, as well as several other high-end speakers I have listened to recently.

The soundstage is now huge and 3D. The piano has the weight and size of a real grand piano and with phenomenal harmonics. I have never heard a better sounding piano on any speaker. The sheer weight and tonality of each note is striking. I thought the piano sounded good on my 645's (and I have a grand piano in my business that is played every night, so I know what it should sound like), but the PHY's are so realistic its scary.

Voices and instruments now have lots of air and there is a realism to these speakers that is hard to describe. The lower-midrange hump has vanished and speaker placement made a huge difference, as well. From the front of the baffle, they are 28" from the front wall and the center of the driver is 26" from the side wall. The drivers are 9 1/2 feet apart center-to-center and the imaging is outstanding. They simply disappear. The soundstage is huge and deep with an incredible mid-range and sweet high-end. It is hard to quantify how much more information I am hearing on the PHY's than my Newforms, but it is substantial.

I am sure the drivers will continue to break in and sound even better, but if they never improved beyond their current state, I would be incredibly satisfied. I was greatly concerned that the PHY's would have no bass to speak of in an open baffle - WRONG. They surely didn't at first, but now the bass doesn't sound much different on a lot of material than my Newforms. I suspect room gain is helping the PHY's. With the 645's, room gain was a problem, but with the PHY's I believe it is a plus.

The 645's clearly go lower, but the quality of the bass with the PHY's is also much better. Let me put it this way; I am going to explore dual subs, but if the bass improves just a little more with break in, I certainly won't feel compelled to add the subs. I don't listen to any rock, rap or organs, so the lowest octaves aren't that important to me. I plan on measuring them shortly to see just how low they are going and where they are rolling off.

I am going to proceed with making my permanent baffles using 1/2" Lexan for the front baffle and Koa for the smaller rear baffle that actually supports the driver. I think they will look great when completed and I am convinced they will sound even better than the simple plywood baffles.

I have a good friend to thank for the suggestion that I try the PHY OBs. I really trust his ears and he raved about another mutual friend's PHY OB's. After talking with the two of them (they both have $$$ high-end systems, go to CES every year and have heard it all), they convinced me that the PHY's were world-class drivers and were incredible in an OB. With a leap of faith I took the plunge.

Since the drivers only cost me about $2,800, I figured what the heck, I'd try 'em. If I didn't like 'em, I'd just sell them and take a bath if I had to.

Well, along with my Berning ZH270 (which I also purchased new without hearing it first), the PHY's are the best audio purchase I have ever made. I will post a follow-up after I finish my permanent baffles, but even with my prototypes, there's no going back to boxes for me. Now I know what the OB guys over at DIYaudio have been raving about.
fiddler
PHY makes some realy good drivers,OB have a very good sound if done right and I feel are over looked. You can use PHY in other designs than a OB but this takes a bit of work to get right and a OB is well easy.If you cant afford PHY other drivers can work very well in OB designs one is fostex f200a. Till later happy listening
Hi Fiddler,

I appreciate that their designed for "o b" but how do you think the phy 30 sag would sound in an enlcosure like the "tannoy autograph" ? or "tannoy grf"

cheers goodo
Hey Fiddler:
Beautiful job. Well done. With every thread I've read at every site (there's lots) and after that review at 6moons, I'm thinking of trying it myself and I have zero experience in woodworking. Its that tempting.
On an aside, have you or anyone else here had a listen to the Audio Nirvana full range speaker? Someone told me it was a very nice speaker (he still has his) and for the price, it wouldn't be a big risk (there's no way I can pony up the dough on a PHY unit just to try it out)

Regards,
nonoise
Using the KM30 in a Tannoy enclosure would be an interesting experiment. There are speakers using the KM30 that are not open baffles. My own Ocellia Kedros is a weird TL/open baffle combination and Hans Kortenbach makes the Auris 2 which uses a sealed enclosure for the KM30. Also Tonian Labs makes a kit for the KM30 in a simple sealed cube. So it can work but how you handle the loading of the driver can be tricky. The KM30 has a very high Q factor because it is designed for OB operation. The driver might be underdamped in a random enclosure.