Carver Drivers Mounting Details

The drivers were purchased by Bryan from Carver (see articles on this in the bass and DIY loudspeakers mailing list for further details) and mounted on open baffles in Canberra, Australia. There is not much DIY skills needed to mount the drivers on open baffles. Bill subsequently had the Carvers at his place for an extensive period of evaluation.

The speaker system is based on Doug Purl's Carver Kryptonite plans from the bass and DIY loudspeakers mailing list together with some alterations of our own. The decision was made to mount the ribbons and the woofers on separate baffles for the following reasons. We reasoned that the imaging of the system would be maximised due to the narrowed ribbon baffle. Employing a dedicated baffle for the ribbons will isolate it from vibrations caused by the many bass drivers employed in this system. As mentioned in the Hi-Fi World articles referred to in the technical description of the Carvers, the bass panels have conflicting positioning requirements for flat in-room bass response to the positioning requirements of the ribbons to maximize imaging. The 60" (152.4cm) ribbons are secured by screws onto two pieces of solid ash hardwood, 185cm (72.8") high by 11cm (4.3") wide by 19mm (0.75") thickness. The total width of the ribbon baffle is 35.5cm (14"). The bass section consists of 5 12" (30.5cm) woofers per side which are mounted on a dedicated baffle board. The bass baffles are constructed from 18mm (0.7") particle board. This baffle closely approximates Doug Purl's Kryptonite model. They are 71cm (28") wide at the top increasing to 91cm (35.8") at the bottom, 194cm (76.4") high. The holes to mount the woofers in were readily cut out perfectly using a router. The nails at the top of the bass baffles were added to hold away from the woofers old curtains draped across the bass baffles to protect them from direct sunlight and dust when not in use. The panel materials used are due to economic considerations only and in no way demonstrate the drivers to their maximum potential. It is important that this point be emphasised because this is the only form in which we have had exposure to the Carver ribbons and we think that with proper mounting this would reap major sonic benefits.

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A close-up of the Carver ribbons/woofers at Bill's place

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A close-up of the back of the Carver ribbons/woofers at Bill's place

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Do you recognise the same Carver ribbons in use here? It's a pity that Genesis has ignored Carver's recommendation of crossing over at 200Hz, thereby avoiding a membrane resonance just below 200Hz due to the tension of the ribbon and the larger 140Hz geometrical resonance due to the 60" length of the ribbon, which may lead to the metal ribbons shorting against the magnets and frame. These resonances are clearly there in review measurements of the Genesis II.5 speakers in Jan 1995 Stereophile which uses the same ribbon for good reason. A much larger open baffle to avoid quarter wave cancellation is needed which potentially has bad effects upon imaging. The tweeters also harm coherence. You can avoid these problems and end up with a speaker on a par with the Genesis costing far less than the ludicrously expensive Genesis if you follow what is described herein.

Bob Carver

For suggestions, comments contact Bill Alford
Last modified 29 October 2001.