Added 10th April 2001

1. There was just too much bass between 30 & 60 HZ no matter how I placed the system or adjusted the phase of the subs.
2. The subs could be driven into overload fairly easily.
3. The DAX was not as transparent as I would wish.
4. The extra mono block amps for the sub were literally in the way.

So I decided to take matters into my own hands and construct replacements that would take care of all of the above squawks on the stock subs. After careful auditioning and I chose the Velodyne FSR-12 . They were quite fast, extended, had a high output capability with a built in amp, nicely sized, the internal x-over was considerably more open than the DAX and finally, they were cheap by high end standards (I paid $700 for each one).

Click on a picture for a large version

As the photos show, the internal components were easy to get at and disassemble. I next measured the volume of the driver and amp enclosures. Talking with an engineer at Velodyne, he cautioned that I must get the volume right and make the enclosure absolutely air tight otherwise instabilities with the servo system can occur. He was quite enthusiastic about what I was doing as the Stage was one of his favorite speakers. Design and construction were straight forward but time consuming. I made the walls 1.5 inches thick out of two layers of 3/4 inch MDF laminated together. All joints were assembled using stud grade Liquid Nails panel adhesive and decking screws. Internal bracing (not seen in the photos) was used to further stiffen the broad top and bottom panels. Special inserts with captured nuts and Allen key head screws were used to secure the woofers. Finally, wood inserts were added to the bottom of each cabinet for spikes. The paint job was an interesting challenge as the Stage was finished in a flat black sand textured finish. Luckily, I found the identical finish available in can form from Rustoleum as a non-skid surface paint for wet surfaces. Two sets of grill cloth structures were made, one for Stages and one set slightly longer to match the Duetta Signatures. Total cost of the new cabinets was under $100 for the pair.

I completed one sub and found it to be, much to my surprise, considerably tighter and dynamic than a stock sub due to it's more robust cabinet. At almost 100 pounds each, these things are heavy but make excellent stand for the Stages. And, if I don't mind saying so myself, they look stunning under the Stages and Duettas, much better than the stock subs.

Click on a picture for a large version

Sonically they are head and shoulders above the stock subs. They are incredibly quick and tight, easily matching the speed of the panels. Bass extension was spectacular and at times just plain thrilling. The overall soundstage and system transparency was significantly improved over even the Stage by itself. Bass panel excursions were noticeably reduced. The stock x-over in the Velodynes works quite well and does a very good job of blending the subs in with the panels. However, the high pass section has a very gentle roll of only 6 dB per octave below 80 Hz which meant that the Stage's bass panel was still contributing significant output in the 30-50 Hz region. This meant that I had to keep a steady hand on the level control of the subs and panels to keep them from overloading the room.

The next evolution was to add an external electronic x-over and bypass the one inside of the Velodyne (the bypass is done with a flip of a switch on the Velodyne's back panel). Two x-overs proved excellent, the HSU unit and the Marchand XML9-3AA. Both are reasonable in price and both feature fast, 24 dB per octave filter slopes for both the sub and the main speakers, user adjustable x-over frequencies (via plug in modules) as well as level controls. If you order a HSU unit, you need to be careful to order it with a FLAT low pass section otherwise it will arrive with a considerable amount of bass equalization added to the woofers output. Both are also slightly more open and resolving than the stock Velodyne unit. I slightly prefer the Marchand unit because I felt it to be slightly warmer sounding than the HSU with a tighter low end. I chose a x-over point of 80 Hz. This completely eliminates any visible excursions of the woofer panel diaphragms during even the loudest of passages. This should help to protect those precious bass panels!

This has been an exceptionally rewarding project. I get solid, tight extension to below 20 HZ and a seamless blending with the Stages & Duettas (I call them my Duetta Grands). Highly recommended!

Click on the picture for a large version

The room is 21.5' x 15.5' x 8. It is a very nice listening room. It has a wood floor that is supported by an old cistern over the first 2/3 of its length. The back third is over a crawl space. There I have about a half dozen floor jacks and 4 x 4 beams supporting the floor under the electronics and speakers. What a difference!! Solid bass. My Slants have solid extension into the mid 20s and the subs can get below 20 Hz.

The woofers have their own internal amps so the Stage/Duettas systems are tri-amped. The amps are by a small company called Reference Line. They are dual mono all the way, including dual power switches and power cords so there is no difference between vertical and horizontal bi-amping.

Attached below are some pictures I took while doing Bi-amp experiments on my Stages/Mini Grands.

The pictures of the electrical components are:

1. The amps I'm using (Reference Line Silver Signatures). The cones on top are not fancy damping devices, rather, they are "feline filters".
2. DAX on the bottom and Marchand XML9-3AA electronic x-over on top

The low pass section of the DAX is cascaded into the Marchand thus creating a band-pass output to drive my "Duetta Grands" in a tri-amp mode.

Jeff Blazey

email: j.blazey@go-concepts.com

"Naked" Stage pictures

Jeff kindly supplied me with a set of photos of his Stages without their front covers and some close-ups of the construction and crossover.

Click on a picture for a large version