Poorion: Orion styling alternative with cheaper drivers

[Andersonix]

Fellow DIYers:

For a few years, I had been deliberating how to build an Orion, but with straighter lines and possibly less expensive drivers. (For some reason, I am uneasy with the SAAB 99 tail on the Orion, and Yes, I know every line and curve has its purpose.) I came up with the following basic shape that has the same hard points (H, W, D, relative driver positions, etc.) as the Orion but is somewhat distorted, although pretty close in the path lengths from front to rear. It also squeezes in two (not perfectly modeled) Peerless 12 inch XLS woofers rather than the 10 inch in the Orion for a not-insignificant 2dB potential bass increase.

In my search for cheaper drivers, I came up with these drivers: Peerless 810921 tweeter ($78) and Peerless mid-woofer 830884 ($75). (Cheaper Peerless plus Orion equals Poorion!) These cost about a third of the price of the awesome SEAS drivers specified in the Orion but are still pretty impressive on paper. The tweeter has 1mm Xmax, and the mid-woofer has a smooth useful response. At Madisound prices that were current several months ago, all the needed drivers cost about $1170 versus the $1833 Madisound package (10% discount) price, which is about $660 less. (Add $100 to the total cost for four 12 inch XLS woofers.)

Other drivers considered were the SEAS 27TBFCG (H1212) tweeter ($43, only 0.5mm Xmax, this is the tweeter actually shown in the model) and SEAS L22RNX/P (H1252) mid-woofer ($92).

At Burning Amp 2008 I discussed my 'findings' with Siegfried Linkwitz, and he said something to the effect that from his experience with the Pluto he has come around to the conclusion that today there are drivers that are 'good enough' for very high performance. Also, at the time he was designing Orion, he searched for currently available money-no-object, state-of-the art drivers and ended up with the SEAS.

I have heard Orion a couple of times, and I do think they are fantastic at any cost and would like to eventually make some. But after I created this model (which still needs much more refinement), I decided instead to get ESLs (ML SL3), so for now I thought I would leave my design and driver findings here on DIYAudio to gestate and possibly inspire others.

Ideas still left to explore:
Separate and isolate the woofer housing from the mid and tweeter housing (which might in effect straddle the woofer housing)
Mold the enclosure from something dense

Tosh

[Andersonix]

The mounting is intended to allow eventually separating the woofer enclosure from the mains.

[cuibono]

Hmmm, well I hope you come back to the design. I've been working on something similar myself, I hope to show in a few months.

One of the things to consider for a mid-driver is whether it can handle the open baffle duty at lower frequencies. The peerless 8" HDS probably would, but most other drivers wouldnt (especially with smaller diameters). I'm using the Visaton B200 (8"), but cross higher because of its lower Xmax.

The SEAS 27TBFCG is a good tweeter choice, and I'll be trying it soon. Zaph's site has other good recommendations. In a couple of recent conversations with SL, he also said to me that there was a point of 'good enough', particularly with driver's nonlinear distortion - something that changed my design priorities some. I'd guess there are a number of equally good tweeters, rated by distortion.

It turns out the possibly the best woofer for OB is the Dayton Audio RS315HF - check out Monte Kay's measurements. Its also a good bit cheaper than the XLS's.

The other major aspect to this sort of a loud speaker is the line level crossover - doing that right, and having lots of measurements is key to this project. The software we have (cheaply) available to us today make that much easier and cheaper than when SL was doing his designs. Its pretty easy to set up the crossover/frequency response/phase correction in the computer, all you need is enough audio outputs and amps!

[Keith Taylor]

Tosh, I like your idea for magnet mounting the mid driver where the brackets land above corners in the H frame. This should reduce the the woofer vibration imparted to the mid compared with the "official" way of doing it. I am an Orion owner and had thought of this approach after noting the vibration in the top of the H frame around the centre.
Keith

[gainphile]

Hi Tosh, I like your design ! ... did you by any chance compare Orion mid to Pluto mid sounds?

Do you know the Fo, Q, and notch depth of orion midrange? Without a plan I can only guess from the transfer function that it is 400Hz with Q of about 1.4 and depth -8db ?

I like the idea of using L22Rnx, they are available ini aussie for about $150 as compared to $500+ for the W22EX. There are plenty of options for tweeters eg. 27TDFC which is very reasonably priced.

[Andersonix]

I don't have the knowledge to alter the Orion XO much, so I wanted drivers that might work with it as-is (except for small level adjustments). I also didn't want to deviate from the 8inch mid-woofer size.

Orion crosses the tweeter at 1440Hz, and I actually didn't find any tweeters that could go as low as the Peerless 810921 and had the same 1mm Xmax as the SEAS Millennium. But with two tweeters back to back, the 1mm Xmax may not be as important as the original Orion which had only one tweeter, making the SEAS 27TBFCG (H1212) a possible candidate, although it has a sharper knee at 2k which may have trouble crossing down at 1440Hz.

The SEAS L22RNX/P (H1252) mid-woofer is not flat above 1k so may need extra help in the XO, while the Peerless mid-woofer 830884 keeps going nicely to at least 2k (according to manf curves).

Keith, I also found the magnet mounting location on Orion to be less than ideal if one is trying to avoid vibrations from the woofer H-frame. And if you look from the side, the whole enclosure is just begging to be split apart at the plane of the woofer baffle.

[Andersonix]

Originally posted by gainphile
Hi Tosh, I like your design ! ... did you by any chance compare Orion mid to Pluto mid sounds?

Thanks, Gainphile. I have heard the Pluto, although not with the Pluto+ 10 inch woofers unfortunately (except briefly at BA2008). It is good in the mids, very natural, perhaps better than anything else for the same money, but I think it would be better still with a better tweeter. Have you seen my design for the Plu-Tosh?

[ttan98]

Originally posted by Tosh
I don't have the knowledge to alter the Orion XO much, so I wanted drivers that might work with it as-is (except for small level adjustments). I also didn't want to deviate from the 8inch mid-woofer size.

Orion crosses the tweeter at 1440Hz, and I actually didn't find any tweeters that could go as low as the Peerless 810921 and had the same 1mm Xmax as the SEAS Millennium. But with two tweeters back to back, the 1mm Xmax may not be as important as the original Orion which had only one tweeter, making the SEAS 27TBFCG (H1212) a possible candidate, although it has a sharper knee at 2k which may have trouble crossing down at 1440Hz.

The SEAS L22RNX/P (H1252) mid-woofer is not flat above 1k so may need extra help in the XO, while the Peerless mid-woofer 830884 keeps going nicely to at least 2k (according to manf curves).

Keith, I also found the magnet mounting location on Orion to be less than ideal if one is trying to avoid vibrations from the woofer H-frame. And if you look from the side, the whole enclosure is just begging to be split apart at the plane of the woofer baffle.

I believe you rarely be able to find drivers which directly replace the drivers(in other words equivalent to Orion's drivers) used in Orion, hence the your X-over/equalizer will be different from Orion.

My suggestion is use a digital x-over, eg DCX2496 costs about US$250 plus $100 for cables, this way you can equalise quite easily, otherwise you need to redesign/mod Orion's equalizer for use in your system. The latter is much more difficult.

Once you are happy with the FR response/phase matching, you can design your own equalizer, at the same time be able to listen to and compare against the digital x-over, if it is superior sell your DCX, easy to resell. You would be able to recover some money.

THis way you can enjoy music along the way.

Cheers.

[jp_howard]

Gainphile: sorry to use this thread as a personal communications channel, but I can't find an email address for you! I'm in Melbourne, and am interested in hearing your OB speakers. I also have some DACs you may like to hear. Could you please get in touch via email? I'm at jeremy[AT]howard[DOT]name . I've sent you a PM via stereo.net.au with more info. Thanks!

(If anyone else in Melbourne has Plutos, Orions, or nice OB speakers, please drop me a line too!)

[454Casull]

http://www.linkwitzlab.com/orion_cha...list of people