scoperta

This tiny new transmission line loudspeaker was established in collaboration with "Troels Gravesen Denmark". Due to it's small dimensions of just over 80 cm height and 19 cm width, it can be a everyone's friend. This TL uses the SEAS W15LY001 mid/woofer in combination with a Peerless HDS 1" Soft Dome (810921) tweeter. As i have good contact with my foreign friend Troels Gravesen, he offered me to design this small loudspeaker....The name "Scoperta" stands for the Italian translation of "Discovery".

Below you can see the half-pipe, constructed of 6mm Fumo (Dutch name) bend triplex. This material has excellent bending qualities, which is usefull on this place, where normal wood would break. Free room under the Fumo is filled with PUR (Polyurethaan foam) to avoid resonance. Before inserting the Fumo, I glued two scratch fillets to hold the Fumo in place.

The section of the baffle, seen on the left photo is back angled approximately 5 degrees. This to improve sound quality on a listening distance of e.g. 2 1/2 to 3 meters. A loudspeaker of only 80 cm high needs some help on sound radiation. All mounting screws will be inserted in M4 metric inserts.

The Baffle is made from a combination of 18mm MDF on 16mm solid Curly'd Maple. This kind of Solid Maple is very rare as expensive, and often used for musical instruments such as e.g. guitars.

Cabinet construction was designed by Troels Gravesen Denmark, designed for MDF panel use. As i used solid wood panels, I had to make some changes, some on cosmetic grounds, some on construction technical grounds. Solid wood is less stable then MDF panels, as it comes to dimension changes due to temperature humidity etc. This is why I made the broken edges on each joint of panels. In furniture talk, equal is un-equal, i.e. if you join two different solid wood materials without transition, it will shift in period of time. Specially when joining woods at different wood structure, this can happen.

Building this cabinets took me a while, making cabinets of solid wood just isn't that easy and fast as from (pre-) venered MDF panels. But the extra effort will be rewarded in the end. This cab's will be spray'd professionally, therefore they have to be sanded. I alway's sand them with medium density sanding paper e.g. 240. After that I remove dust ,and moisturise the surface with water. Let the cab's dry, and sand them again with 400 sanding paper. Moisturising the wood will rise wood fibre after drying. So the final result will be more smooth.

After sanding the solid cabinets, they can be spray'd. I took them to a professional sprayer, were they got two layers of 2-component High-Gloss natural spray. This laque will be as hard as car laque in a couple of day's. To give a impression on the size of this mini T'L cabinet's, my 2 1/2 year old daughter is showing them:) Just over 80 cm height (including foot) is not that big, and should fit in most living rooms, without getting any wife trouble:)

After adding internal wiring, and adding MDM3 damping wool, it's time for mounting drivers. This black frontplate's make a nice appearance on the wood structure of the cabinet's. Cab's give a very solid sound when knocking on them, this solid wood structure contributes on this, I'm sure.

Now it's time to start soldering the X-overs. These mini TL's were designed by Troels Gravesen as mentioned before, so honor who honor get's by. For X-over schematic see his web-page. X-over parts (or complete set, excluding HDS tweeter) can be ordered at Jantzen audio Denmark, Troels made a complete order list, as seen below.

As these cabinet's leave not many options to mount X-overs, (mounting them inside the cabinet's will impede air flow) I had to search for other options. So I came to the 26mm optional foot beneath. This height together with the 12mm depth routed basic MDF plate, makes a total of 38mm. Just enough to house the X-overs, that is, if you be satisfied on using standard quality X-over components. High (expensive) quality components, are much bigger, and will give room problems on this place.

On the base of the cabinets I made some aluminium edged profiles (20x20x1,5mm) this gives a nice front appearance and protects the wood bottom fillets from damage. As seen on the photo, X-over parts will be easy fit this room. Only three capacitors, three coils, and a couple of resistors are needed for this loudspeaker.

X-over lay out is quite easy and won't give any problem's. I only used half the space I had free for this X-over. It can easily be mounted on a 12x15cm board. The complete X-over is fixed by 2-component resin, which makes is rock solid, and free from vibrations. The 2R2 resistor (resistor R1011) is placed in a way it easily can be replaced by other value's. This may be necessary to tune tweeter value to you're personal taste.

Some technical data on this loudspeakers:

Sensitivity: 85dB/2,8V

Frequency response: 50 - 20,000Hz

X-over point: 2800Hz

Weight: appr.15KG / each

H x W x D: 800 (830 incl.foot) x 190 x 220 mm

It gives me joy time after time to transform a raw piece of wood to a nice looking piece of "furniture" , let's be economical on this great gift of nature....and only use FSC wood.

Some comment about the sound of this loudspeaker:

This tiny transmission line speaker play's with great joy on my 300B SET amplifier. As I am a big fan of tube amplifiers this came as a suprise for me. With "only" 85dB efficiency my 300B amp will not produce earthquake basses. Off coarse not, but bass lines are very good, and produce enough air flow to enjoy the sound. I am curious how this speaker will perform on my future KT88 Push-Pull amp. The soundstage is very good, and instruments are placed at their correct places. This speaker simply disappears in the room, it delivers the sound to you're room without saying, hey I'm here. Stereo imaging is very good, and they will treat you by a very natural sound. You will love you're music more then ever before....Thanks Troels!

Complete cabinet construction is glued with "Lamello" biscuit's to establish a solid contruction. The backside of the woofer fitting is chamfered to allow free air flow into the chamber. Right you can see two tiny drilling holes, to allow tweeter wire connection. On the front these are routed with 15mm depth, to allow tweeter placement. See picture below.