Our first Perfect Pitch project is this BS1 two way bookshelf loudspeaker with the excellent and affordable Ciare loudspeaker drivers. The BS1 has smooth low bass down to 50Hz, impressive dynamic and clear highs and supreme voicing due to the tweeters large voice coil and that in a relatively small, not very expensive to build, unit that sounds a lot larger that it actually is.
The loudspeaker easily outperforms most mid level HiFi bookshelf speakers on the market that come on a significant higher price, even 3 to 5 times more expensive than the Perfect Pitch BS1.
The rrive units used in this project are the Ciare PT383 with 38mm voice coil tweeter and HW172 7 inch woofer, cross-over components are excellent quality, non exotic, of-the-shelf parts.
How the Perfect Pitch BS1 sounds …..
The words describing the sound we heard from listeners where 'impressive', 'unbelievable' and 'It sounds like an expensive large floor stander'. One of the people who listened to this unit even said 'I wish I had this 30 years ago'.
Personally I prefer the units even over my 5 times more expensive DIY floor standing speakers, they just sound so inviting.
Positioned correctly in your listening or living room this unit will absolutely astound you.
The system is easy to drive with almost any power amplifier even driven with a 10 watt tube amp the BS1 will rock your world.
The cabinet is made from standard 22mm thick MDF that you can purchase from any local hardware store. If you prefer you can go for a more compact but more expensive type of MDF which raises the resonance frequency of the cabinet a little but this is not really necessary if applied damping materials do their job properly. That type of MDF is usually available only on special order or in specialized shops so not very convenient. The loudspeaker stands are also made from the same material supported with some dowels to keep things attached. A standard 240x122 cm MDF panel in our country costs around 25.00 euro and you can get all necessary panels for 2 speakers and speaker stands from this panel.
Materials and tools list;
Perfect Pitch BS1 kit
MDF 22mm panel 240 x 122 cm
8 pieces 6mm dowels (for stands)
wood glue (large bottle fast drying)
wide masking tape
bottle of thinner to wipe MDF before gluing and painting
paint (base for MDF and paint to finish)
table saw, router and obvious hand tools
The cross-over is basically a 12dB Linkwitz-Riley with some additions for driver impedance correction and a attenuation circuit for the tweeter.
Cross-over frequency is set very low to get the most of the impressive 38 mm voice coil tweeter.
Fig.5 and 6 show our prototype cross-over and it shows the way we prefer to set it up mounted to the plywood panel with hot glue. This works fast because you can go on with construction as soon as the glue cools.
If you build it like this connections are short and no additional inter component wiring is necessary. Components are glued with hot glue and set up in a way that they do not interfere with each other, parts in a cross-over actually do you know, also it is more compact this way. Detailed drawings for wiring the cross-over are supplied with the kit.
When panels are cut at a 45 degree angle like in fig.3 putting together the cabinet should be very easy to do with some fast drying wood glue and masking tape.
Before gluing together the panels make the round holes for the speakers in the baffle, front panel, and the bracing panel with a router according to the measurements in the build plan. When you are done with that you must wipe the MDF pales with a soft cloth with a little thinner, make sure to let the thinner evaporate before applying glue, to remove any greasiness and dust and glue them together to make the box.
Put masking tape on the outside of the panels and apply glue to all panels all at once and fold the panels together to get the box, don't forget to put the bracing panel in the correct place. After folding the panels together wrap the box with additional masking tape and let it dry for a couple of hours.
After the glue has dried you can saw and drill the holes for the port tube and terminals and get stared with routing the edges of the box. All vertical edges need to be rounded with 10mm and horizontal edges angles at 5mm router bits.
When done sand the panels very well with 400 sanding paper and wipe the panels again with a cloth and a a little thinner before you apply the MDF base paint. After this has dried sand the panels again with 400 sanding paper and apply the finishing paint in two or tree layers, let it dry between paint jobs.
Glue the cross-over to the back of the box with wood glue and after that damping material 'TYROFOAM10' is glued to the inside of the panels a shown on fig.7, spray glue or other inexpensive mounting glue will do. Don't use staples, I heard somebody use them, as they can come lose and damage your drivers.
Cotton wool is used to fill at the back of the box up to 1/3, don't fill the box up completely just the back around the vent and over and around the cross-over.
You can now mount the drivers, first apply two rows of tape, one on the outside and one on the inside of the cut and pre-drill the holes where the screws will come. Use the screws supplied in the kit to mount the drivers.
Parts used in this project
Backplate wirh connectors for PWA-01 power amplifier
Stereo High-End Headphone Amp for modular preamp