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, for those not familiar with your project can you give us a little more background information. Who makes PHY's and what is their web link? Did you design a cabinet from scratch and if not, give us more detail? What XO's are you employing in this design? Are they 1st order, 4th or what?

Lastly are these for 2 channel, HT and personally use only or are you considering selling to others?

A keyword search over at the asylum will answer all your questions in less time than it took you to ask.

A word of warning-Don't start your research unless you are prepared to pony up the dough for the drivers.
In reviewing the web info, it is helpful to speak French. Some, but not all info is available in English.
Faugusta, if I would have known the asylum had answers to all my questions I wouldn't have asked them, now would I?

$2,800 for drivers is a drop in the bucket. I'm ready to pony up a lot more than that... if I know what I'm getting bests what I currently have!
Dawgbyte, the website is:

I hope that works!

The open baffles have no cabinet, just a flat front baffle. I found lots of info in this thread. Its a long thread!

Also, here is the final design that I am going to use with some modifications:

No crossover is employed.

Only two channel use for music.

Selling to others? Are you kidding. These things are so simple to make and sound so phenomenal, I can't imagine why there aren't tons of people already using them. I know I would have long ago if I had known about OB designs and the PHY drivers.
Dawgbyte, here is a quick picture of what the speakers will look like:

I have the PHY KM 30 SAG, which includes a time-aligned tweeter, so my baffles will differ from the ones shown by eliminating the add-on tweeter and crossover.

Here is the PHY KM 30 SAG driver:
Aloha Fiddler, Are you still driving your KM 30 with your Berning 270? I would love to have a listen, if who you are, im in driving distance to you. Mahalo Wally
Hi Fiddler, I am going to build an open baffle loudspeaker based on Phy HP KM 30 SAG, too. I wonder why PHY-HP suggests a huge baffle in their website (, while yours is smaller. Of course, your baffle is much more compatible with a normal room size and, furthermore, it looks very nice, but do I have to expect any difference (e.g. in bass response) with respect to the PHY-HP suggested baffle project?
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)

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.
I am an Audiogoner that purchased a pair of PHYs almost a year ago and am responding to your email. Now that I'm acclaimated with the speaker in my 15' x 15' room I can speak on it. Terrific, the wings on the baffle help in the tuning process. I've tried it with and without wings because the speaker size looked imposing in my room, but I must say the wings on the baffles produced better staging and better bass. I'm currently using a borrowed Roger Majeski 6EM7 5 watt Single ended amp with the Promitheus TVC preamp. Without question, if no one has auditioned this EM7 series amps...PLEASE. I plan to purchase the 12watt version though the 5 watter is fine it's just good to have that versatility for less sensitive speakers.
(1.) Link for the EM7 series
I will send to your personal email a picture of my Open Baffles
hi Fonz

I was hoping you might shoot me a pix or two of your PHY OB;/s and tell me what you think of them at this point? Which model? Source? thanks so much, I am about ready to pull the trigger on a pair of HP210 regards, Dan
Fonz I would love to see pics as well
I've been speaking with Tonian Acoustics on their phy designs and would love to see what you have mustered up

Please e mail me with your comments when you have time
Sure Dan
Hit me on my home email: and I will gladly reply with pics. My system is in a state of flux. I'm getting off the merry-go-round and am going to settle on my last pair of speakers. I'm halfway to the Avantgarde UNO on the "GON" but I have too much into the PHY driver and solid cherry baffles to let them go cheap. I'm devoting all my time to woodworking which is my first love, actually second to my wife and Kids. As nice as the PHY is, if I hadn't heard my friends UNOs earlier this week in GA. I would have been happy.
Best regards,
I'm sorry I left you out. My email is
I will gladly send pics.
Beautiful Fiddler, simply beautiful. I've read about the PHY drivers for some time now you've gone and done it.
I am absolutely useless when it comes to woodworking etc. If I took the Battle Plan OB plan on the PHY-HP website to a cabinet maker are they definitive enough for him or her to produce said speaker design?
A customer of ours brought in a set of PHY KM 30 SAG 12" speakers, based on a series of reviews he read. One of the reviews recommended that our amps were a good match so he ordered a set of those as well.

I have to say the PHYs were quite impressive! At first we listened to a set of SET amps, and really, they did very well, although a bit odd (colored? humped?) in the bass. When we got our amps installed that and a lot more was transformed- it was easy to see why the reviewer (who was in Hong Kong) made his comments (although its hard to say how much was amplifier and how much was break-in- refer to earlier comments to see how important this is). A really nice easy load for any tube amp too. 16 ohms really contributes to improving transparency in tube amps as you reduce distortion that masks low level detail.
I really want to see som pictures of your open baffle "Fonz". I just got my hands on a pair of KM30 SAG drivers and gonna start building a open baffle or a box with open back...

I don´t have room for the recomended open baffle from PHY-HP website so I´m really interested in yours.

Do you still have them?

I believe I have some pictures I can send you, the full and small scale.
Hello Fonz,

Based on your system, looks like you moved on from the PHY's?

I have a pair built into an OB, which I love. I was curious, however, how you went about making connections to the drivers. I'm currently using disconnect tabs to push onto the metal tags, yet was curious what you did. Did you solder wire directly to the metal tags? For such over-built, beautiful drivers, it seems beyond bizarre to have such a critical juncture serviced by what appears to be a 10 cent piece of tin, but I trust they know what they were doing.

Any help you can provide is appreciated (and I'd love to see the photos you mentioned if you have them handy). Thank you in advance for your time.

All best, Andrew