DSK
Ohhhhh....ahhhhhh......If the one speaker I heard that Rick built is any indication (early model, mid-size 3-way standmount, paper 6.5", 2" dome (Morel?), maybe 3/4" dome, he is absolutely one of my favorite dessigners. I favor Rick's design goals. Other than what I currently have a pair of Rick's would make me a happy camper. I am looking forward to hearing Rick's speakers at RMAF '07. When I used to build speakers I thought of Rick's same blending of driver size diameters. It's odd that its not more common. Just for the heck of it, immediately after hearing Rick's speakers I heard a pair of Theil & B&W. Both were imminently unmusical vs. Rick's.
Pictures later after I change some metal nuts to nylon, arriving soon. Here's the 2-page post description:
Jimbolya Post Technology + Outboard XO Interface, by Jim Romeyn
Rather than standard metallic binding posts (20 posts sum total for this speaker project), nylon flat washers, nylon lock-nuts w/ shoulder, & nylon knurled-thumb screws w/ shoulder are utilized. A supplier for all parts & part numbers are mentioned below. The non-conductive fasteners only clamp the spades together; the signal no longer travels through any type metallic post, nuts & associated threads & wire terminals. No large, unnecessary conductive parts are utilized. This is the purest form of speaker interface other than solder or wire nuts.
The nylon screw heads go inside the terminal boards to expose the threads outside the boards. Slide a washer on the screw to elevate the lower lock-nut, which increase finger clearance to ease attaching the spade terminals later. The lower lock-nut then secures the screw to the terminal board. Another washer goes atop the lower lock-nut to maximize the clamping & tension area of the spades. Attach the top lock-nut loosely to leave room to insert the spades later.
Later when the speakers are set up, two spade terminals will be clamped together between the upper washer & the shoulder of the top lock-nut.
Use moderate torque on the nuts to avoid stripping the nylon threads.
The Outboard Xo (OXo)
Binding Post Inputs: Biamp/biwire inputs are featured. There are two terminal boards sited vertically on the input side-panel. Each terminal board has one pair input binding posts, centered, vertically sited, & labeled from the bottom up: “Below 280 Hz”, “Above 280 Hz”. The posts are sited close to the top of each terminal board to ease fastening the spades later. Drilled about 1.4” below each pair of binding posts is a 3/8” hole finished w/ a black plastic collar sleeve insert.
One wire pair per input range passes through its respective sleeve described above. The wires are cut about 6” from the OXO enclosure, are terminated w/ tin-plated copper locking spade terminals, & then attach to their respective binding posts.
Speaker cables from the amp(s) are terminated w/ spades as above, which attach to the OXO input binding post inputs.
Shorting jumpers are required for single-wire use.
Output Cables: The output side-panel is opposite the input binding posts. Three 3/8” holes are drilled, centered & in a straight vertical line. Each hole has inserted a black plastic collar sleeve. The holes are labeled from the bottom up: “Bass”, “Midrange” & “Treble”. One wire pair per output range passes through its respective sleeve. The wires are cut about 15” from the OXo & terminated w/ spades as above, & then the spades attach to the speaker input binding posts.
3-Way Speaker Inputs
Input Binding Posts: The speakers are 3-way w/ two terminal boards sited vertically. The lower terminal board has one pair of input binding posts while the upper terminal board has two pairs. The posts are centered, vertically sited, & labeled from the bottom up: “Bass”, “Midrange”, & “Treble”. The Bass posts are sited close to the top of its terminal board to ease fastening the spades later. On the upper terminal board the Mid posts are sited at 1/3rd height, the Treble at 2/3rds height.
Drilled just below each pair of posts is a 3/8” hole finished w/ a black plastic collar sleeve insert. One wire pair per input range passes through its respective sleeve described above. The wires are cut about 6” from the terminal board, are terminated w/ tin-plated copper locking spade terminals, & then attach to their respective binding posts. Inside the speaker the sleeve holes are air-tight sealed w/ hot melt glue.
Wire Terminations
It is commonly recommended to only crimp the spade terminals & to avoid using solder.
Theory
The British Eichmann Bullet brand RCA plugs are well-known for high sound quality. Their unique feature is conducting the ground signal via a tiny pencil-point-size spring-loaded metallic ball located at the narrow leading edge of an otherwise large non-conductive resin collar. The sum total of the conductive mass equals only the tiny metallic ball. There is similarly little conductive mass to Radio Shack’s RCA plug #274-321 (8/$2.99), which may also explain why they perform well even though they are easily broken. The Jimbolaya Technology mimics the philosophy behind the Bullets & R.S. RCA plugs.
Parts Supplier & Numbers
McMaster-Carr supplies nylon fasteners & tin-plated copper locking spade terminals:
www.McMaster.com1. Off-white nylon lock-nuts w/ shoulder, p/n 94909A181, $8.65 for 100, need 20
2. Off-white nylon flat washers, look up p/n, last purchased somewhere else, need 40
3. Black plastic push-in wire sleeves, look up p/n, last purchased somewhere else, need 16
4. Off-white nylon knurled-thumb shoulder screw, 1/4”-20 threads/inch, p/n 94323A541, $12.51 for 100, need 20
5. Tin-plated copper locking spade terminals w/ yellow vinyl insulator, p/n 8007K53, $8.94 for 50, need 40
Please all who try this post your results. If you like it, remember Jimbolaya told you about it (referred to as Jimbolaya Post Technology or JBT for short). If you dislike like, leave me out of it…
