BePure2.5??

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c_note

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BePure2.5??
« on: 15 Dec 2022, 09:31 pm »
Jim, congratulations on the success of your BePure speakers--they look (and, I suspect, sound) spectacular.

I have no doubt that the BePure 3's are great speakers, but I suspect they could be too much for smaller/normal-sized rooms, and their cost puts them out of reach for many.  Have you considered creating a 3-way speaker with the 6.5" Purifi woofers?  Specifically, I'm thinking of two 6.5" Purifi woofers per speaker, the Satori MD60N 2.5" dome midrange (utilized from about 900 to 3,500 hz), and a smaller beryllium tweeter like the Bliesma T25B-6 (by all accounts an outstanding tweeter, with less moving mass and better off-axis response than the larger SB Acoustics counterparts).

It seems this configuration would have many advantages:

1.  Basically the same dimensions as the BePure 2, so very compatible with smaller rooms, and high wife-acceptance factor
2.  Improved dispersion/reduced beaming, both in the critical upper midrange/ lower treble area (due to dedicated midrange) and in the upper treble, due to the smaller diameter tweeter
3.  Improved intermodulation distortion, as the woofers no longer have to reproduce both low frequencies below 80 hz and higher frequencies above 1Khz
4.  Near state-of-the-art performance from 40 hz to 40KHz, at a much more accessible price point than the BePure3.

Food for thought only, I'd be curious how other forum members respond to this idea.

Happy Holidays to all!

« Last Edit: 16 Dec 2022, 02:18 pm by c_note »

Rusty Jefferson

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Re: BePure2.5??
« Reply #1 on: 16 Dec 2022, 12:21 am »
I'm just going to take a wild stab at this one.

He's got the Song 3 Beat which is just a lovely speaker for a smaller/medium sized room, and the Encore if you'd like something a little larger/deeper, both 3 ways. Spending about $1800 just for four Purifi woofers to play up to 900hz seems like a waste? Then you still  need mids/tweeters a 3 way crossover and a cabinet. That's still going to be a pretty pricey speaker?

RonN5

Re: BePure2.5??
« Reply #2 on: 16 Dec 2022, 04:32 pm »
I would guess that adding a high quality midrange would easily add $1k to the BePure2 price…and then, compared to the Song BeAT3,would the two purifi bass drivers put out as much bass as the BeAT3 7.5” Satori driver?

jsalk

Re: BePure2.5??
« Reply #3 on: 16 Dec 2022, 05:10 pm »
Not having much time to think about this, here are some off-the-cuff comments (subject to change with further evaluation)...

The Purifi drivers are ultra-low in terms of distortion.  So I don't know how much improvement there would be in terms of midrange sound quality by doing a 3-way using a dedicated Purifi midrange.  These drivers are so clean, I don't know if you could even tell if the midrange distortion levels were lower.  They are already extremely low.

And you would be going from dual 6.5" woofers to a single 6.5" woofer.  So the bass output would not likely be near as good and the sensitivity would be lower as well.

A customer has requested a pair of Song3 BeAT's with a Purifi midrange.  Without going to OEM Purifi drivers, the only one with enough sensitivity is the 6.5" Purifi midrange driver.  So when finished, we'll have a good idea of how much improvement can be gained and what the cost of the "upgrade" would be.  This, of course, is a slightly larger speaker than the BePure 2's (which actually play 1 Hz deeper and are 90 db efficient).

I'll try and remember to post some impressions when we finish this upgraded pair of Song3 BeAT's.

- Jim

c_note

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Re: BePure2.5??
« Reply #4 on: 19 Dec 2022, 06:44 pm »
Friends, I apologize, I didn't express myself well.  The speaker I am envisioning is essentially the BePure 2 with an added 2 inch dome midrange from Satori that currently retails for about $175/unit at Madisound.  So, per speaker, two Purifi 6.5" woofers, a small dome midrange, and a small beryllium tweeter.  Let's be exceedingly generous and assume that adding the dome midrange driver would add approximately $1,000 to the cost of a pair of BePure 2 speakers ($175 per unit, incremental crossover parts, labor, assembly, routing, etc.)

Adding a dedicated midrange driver probably would not lower distortion levels, as the Purifi drivers are already state-of-the-art in this regard.  However, the laws of physics demand that a speaker driver starts beaming when it's size becomes comparable to the wavelength of the frequency being radiated. That's why tweeters are small, and the smaller the tweeter, the better the dispersion and the broader the "sweet spot" for listening.  7-inch drivers start beaming about 1 kHz, and it becomes especially noticeable in the octave between 2 and 4 KHz, where most 2-way speakers are crossed over.  A dedicated dome midrange would eliminate beaming between 1 and 4 KHz, providing a more graceful transition between woofers and tweeters, while simplifying each driver's job.  Also, the moving mass of a dome midrange is far less than a 7-inch woofer, particularly helpful in reproducing lower treble frequencies.

Again, food for thought, only.  I think this simple addition could elevate the BePure 2s to true state-of-the-art speakers from 40 Hz up, while retaining the BePure 2's small footprint and high wife-acceptance factor.  Once the economy starts to recover, and my stock portfolio finally starts moving upward, I may ask Jim to build me a pair--fingers crossed!

DMurphy

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    • SalkSound
Re: BePure2.5??
« Reply #5 on: 19 Dec 2022, 07:10 pm »
Just for the record, the BePure2 is crossed at 1900 Hz, so any woofer beaming issues are not severe.  Also, I have no working knowledge of the SB dome midrange, and such designs have proven problematic in the past.  But I agree that, in principle, the 3 way design would have an advantage.   However, I doubt that Jim wants to add any new complexities to his product line. 

RonN5

Re: BePure2.5??
« Reply #6 on: 19 Dec 2022, 08:49 pm »
cnote

Maybe from the standpoint of having room filling 180 degree sound, a small midrange driver could help. 

I owned the Veracity STs and with their dual 6" woofers that crossed somewhere near where the BePure2s cross...I never experienced beaming in my listening position 10' back or for that matter 5' on either side of the LP.

I think the top two charts on this link help to explain why....

http://www.audiomeasurements.com/?p=3589

What always surprised me about the STs was that the "little" Seas midwoofers were not only producing deep bass but a really beautiful midrange as well...and Jim has said that the BePure2 is even better.


Rusty Jefferson

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Re: BePure2.5??
« Reply #7 on: 21 Dec 2022, 03:18 am »
c_note,

From a purely engineering perspective all your points are correct. However, the beauty of the Purifi woofers is their midrange quality. I believe what Salk is doing with the BePure 3 model is likely the best solution audibly. Perhaps a reasonable middle ground would be a Song 3 Beat (style 3 way) with a single Purifi mid and an 8" or 10" woofer in a medium-ish cabinet?