Anyone build a Rondo Inspired Speaker?

FLEAWATT : Fleawatt Betsy Cello Speakers

this guy built them for his betsy drivers.

I don't think it looks any more out of place than the green colored driver that is on the Auditorium23 speaker.

Fleawatt and @Cervelorider are one and the same. He builds nice stuff, maybe he can comment on the sound this speaker makes and construction technique? If it truly is an empty open box with the bottom open, the sound coming out might be kind of a mess - some damping would seem to be called for.

I will try to simulate this in AkAbak - maybe I will try it with a budget Visaton BG20? I will have to estimate dims from the photos though - this appears to be quite a voluminous speaker. I am thinking a 5 in driver would be pretty nice to have to get the cabinet a little more compact.
 
OK, I looked at the review for the Musical Affairs. This looks like it is intended to be semi-resonant body like a violin with the "vent" a tall slot at the back along the whole height - like a terminus restricted open baffle. Open baffle high Qts high efficiency drivers should be used. Makes perfect sense to use the BetsyK for an economical approach. Those PHY's cost 2000 Euros! The use of triangular wooden blocks for an anechoic wall at top and bottom is interesting - but egg carton acoustic grey foam may be an easy alternative there. There is also a wedge deflector directly behind driver to prevent reflections back into cone. Very interesting design but as the reviewer said, very sensitive to placement - by mere mm's makes a difference. That is not good.
 
Hi guys. I'm happy to answer any questions you might have about the resonant style enclosure I used for the Betsy drivers.
The plans I used came from Troels Gravensen.
Greencones
They are a resonant cabinet. They are meant to impart their character on the sound. This isn't for everyone. Especially those who place a priority on measurements vs. listening pleasure. With that said, many of my non audiophile friends and my wife prefer them over some of my more "accurate" speakers.
 

talaerts

Member
2005-10-15 8:09 am
Not exactly a copy of the Rondo but certainly inspired, this German design seems worth investigating:

Breezer

breezer.jpg
 
Simulation of a Rondo-inspired design for Betsy K

Based on an 'open bottom' enclosure from the Rondo, I made a quick design using the Betsy K driver and sim'd it in AkAbak.

The baffle is 24 in wide and make the curved rear sections such that the CSA is 384 square inches x 60 in tall, with 4 in legs to allow a gap of 4 in clearance at the floor. The lower window brace is assumed to be 0.5 in thick plywood and provides 80% of the max CSA or 307 square inches. The driver is mounted at 25 in from the top, and the speaker is placed at 70 inches away from the back wall (measured to the front baffle). It requires quite a bit of BSC to get the rising response to go down level: 6 ohm and 1.5 mH in parallel before positive connection to driver.

Simulation with no stuffing or damping and 2.83 V of driver input gives the following frequency response and cone displacement plots:
 

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