Arvo Pärt Supreme? It's not my fault!!

[JonMarsh]

Ever have one of those days where you're busy as all get out, and then something pops up that totally blows you off course, but it seems so natural and logical you just can't put it down?


Well, Steve did that to me today... sent me a link to this somewhat exotic and obscure speaker being produced in Europe and reviewed on Mono and Stereo....




Now, here's the bad part- the page I landed on was just a picture of the speaker, and no, there isn't actually a review!

But I recognized the HF driver right away, the Beyma TPL150H, which I have on hand...

Of course, what's the next thought to enter my shallow empty head but, "Hmmm, I wonder if I could build something like these relatively easily?"

Of course, "relatively easily" is a very relative concept... thoughts of a true Arvo Pärt Supreme starts evanescing in my head, like what happens if you get the cork ALMOST out of the champagne bottle and it just starts oozing up faster and faster in the slight crack available, and you'e better have it over the sink or you'll have a big mess on your hands...

Well, I didn't have a mess (yet), but I did spend just a wee bit of time researching the basics of how one might go about it... following in the footsteps of this design, with a passive midrange and HF crossover, but an active LF with EQ, taking it's signal from the speaker line inputs. You know, the way a number of plate amps can do these days. So, if you want to use your favorite SET on the top end, or a low power Pass Class A (like the unassembled kit I have), no problema.


Hmmm, so how hard would this be? Need a smooth extended 8" driver with consistent off axis behavior, and need some dipole class 15" woofers, preferably with a Qts around 0.7, a reasonable inductance and cone behavior up to 400 Hz, and a nice stable suspension setup with something close to 20mm of Xmax, and all at a price that won't break the bank.

What could go wrong?

Hmm, 8" drivers.... I wonder if Faital has anything new there, something super smooth like some of their 6-1/2" pro drivers...

A very little bit of searching there, and I find a brand new part at both PE and my favorite French distributor...

FaitalPro 8RS350








Yes, yes, I think that will be fairly easy to work with from 150Hz to 2kHz.


Now, woofers? PE doesn't specifically offer "dipole woofers", but check out the UM15-22....





Seems like Dayton was reading my mind, for what I want...

• Basic LF sensitivity close to 90 db? Check...
• Qts around 0.707? Check...
• Fs around or just a little below 30Hz? Check...
• Achieved via high MMS but relatively low CMS to keep things from flopping around in the breeze too much? Check...
• SUBstantial power handling? Whoa momma, check indeed!
• Clean cone behavior at least up to 400Hz... Check!

Double spider setup with particular attention paid to anti-rocking behavior under long excursion... Yup, just what we need!





Well, reality is I'm pretty swamped right now, so I'm just throwing this out to the forum as a concept for a design study or whatever and however far anyone would like to take it...

But eventually I expect to get around to it, if none of you do... it's just too logical and straight forward. I think even Spock would like it. And then there can be one more version of Arvo Pärt dipole.

[ergo]

Intriguing, most intriguing... I've been away doing "bigger project" - a house sized one.... actually two house sized ones.

I occasionally come here lurking around in evening, but this cough my eye.
- ... been thinking to do an open baffle project once I get my big project in shape - check
- ... this being Arvo Pärt, what would be more suiting than to co-create this in a country of his birth

so I might take you up on your challenge, but not right away. New workshop is getting there but some push is still needed and same with the main house. I can do the research though and order drivers etc.

Any thought on the HF end of things. Do you recognize that unit too?

Greetings from Estonia
Ergo

[Steve Manning]

Very nice Ergo, looks like a nice size! Are you doing the building?

[ergo]

I do as much as I can yes. The main frame was a brought in as modules and assembled by the team and the roofing and exterior I had done by pro's. Floor insulation and covering I did myself, and now this weekend the horizontal slits in preparation to get it PU foam insulated soon. Need to figure out few ventilation holes still and route electrical cables for outside light etc....

Was just looking at video review on CO2 lasers and realized that I better make a hole in a wall to exhaust such a thing direct to outside as well... so yeah that is how it is and why speaker building is stalling at moment .... but all in hope one day it will be that much better.

Size inside is about 29feet times 18feet (9m x 5.7m)

[JonMarsh]

Greeting to you in Estonia from me in Idaho!

Regarding your picture, you know my favorite saying from a retired Siemens Semiconductor colleague, "Slow work takes time", but you are making progress- it reminds me of Steve's workshop construction in Maryland.

As I VERY briefly mention, the HF unit I recognized immediately, it is what caught Steve's eye also, being a Beyma TPL150H driver. This is the combination of a TPL150 + the Beyma waveguide. I've looked at quite a few AMT style drivers, mainly because I have a set of Tuk Kanto speakers using a small AMT driver that sounds pretty good in that desktop application, but the only two I've found adequately "interesting" (as ET would say) so far to work with are the TPL75 and TPL150 from Beyma. Too many limitations in the others, but then, these were designed for professional applications, and the pricing from some European distributors is reasonable- part of why I have a wholesale account at TLHP. Considering what a ScanSpeak Be tweeter costs these days, if you can even get them (material delays and "temporary" unavailability), the TPL150 is reasonable. And with the waveguide it also lines up the Z axis fairly well.




And a snapshot with waveguide ready to mount:



And a test measurement with a POC LR4 crossover concept for another project in development, (for which this part is likely over kill)



Too much ambient noise, but it confirmed the basic characteristic.

And another measurement, 2400Hz 2nd order Bessel, with distortion:




Resonance free impedance curve, as one would expect. There is a "smooth" hump in the raw response... peak sensitivity about 103 dB.




This is 0-10-20-30-40 degrees. Rated operating range is +/- 30 degrees horizontal, so this seems OK. I can see why they chose this combo for a dipole system.

And I figured if you did come by and see this post, of course you would have to mention the birthplace of Arvo Pärt, which is very appropriate!

Anyway, I think you can see why I was intrigued by the possibilities of the commercial design, and think I uncovered a reasonable set of choices for a possible DIY development.


And I am very aware how other activities can delay DIY activities, even without a normal day job myself, there are still so many other things to attend to!

With warm regards from Idaho,


Jon

[JonMarsh]

I just sent off a message to tktran following up on some topics about drivers we've been discussing, and responding to his questions about my experience with other Accuton besides the C173-6-090, and the exchange reminded me that I have a pair of Accuton C168-6-890 on hand, which is a relatively new midrange-mid woofer design with some innovations based off the CXXX midrange series with large voice coil but with a long VC and magnet and motor design putting it in the mid woofer range as regards Fs (41 Hz) and Xmax (+/-5mm).













Now, with Accuton, what I always do is check out the distortion plot, to see how the best case performance is and where you have "issues" from resonance amplification of distortion products.





Looking at this, I'd say we'd be in pretty good shape from 200Hz up to 2kHz- the only issue is I'd like to see more sensitivity, so I'll need to do a POC measurement to see if it would be usable- it's about 5 dB lower than the Faital part. But the distortion might make the difference, and also in the Accuton's favor, I already have a pair!