July 23, 2012

Bass modules for horns

Currently working on an 18" flat pack for TD18 to go with a Unity horn:

1. Sealed 90L - designed specifically for Acoustic Elegance TD18H (shown with S3)

This enclosure is designed to allow the box to be pushed into a corner with a horn on top. This design also makes the box more rigid. As used with S2 and my own woofer boxes previously:

When combined with Acoustic Elegance TD18H, this is the ultimate bass box. For a lower cost, it may be used with a Celestion 18" which I can supply at a good price. This is a good bang for buck option.

2. Vented version - 150L with a Celestion 18" woofer

 This is a good choice for systems that don't have a subwoofer and don't require extension below 40 Hz.

Other versions available on request. Unless you already have drivers, I recommend a choice between TD18 and Celestion. The Celestion drivers are great bang for buck, but the Acoustic Elegance is the ultimate if you are willing to pay a premium for the best.

Shown below is S2 with my own 60L sealed boxes. These were built manually, but flat packs will all be CNC cut.

July 17, 2012

HE2 progress

The box for HE2 is almost complete. This one was built manually and it's the demo/prototype. It features a very narrow baffle for 10" drivers with a 13mm roundover and a generous shelf port which eliminates port compression. Bitumin rubber damping also makes the box more dead. Future versions will be CNC machined to keep the price down.

The internal compartment behind the midwoofer will be completely filled to keep the midrange clean and neutral. Most of the box won't be filled to preserve the bass response.

The crossover will be mounted behind the waveguide. You can see the texture of the side walls where bitumin rubber has been mixed with 6mm screenings. The bitumin rubber adds both mass and damping whilst sealing the box. 

Once finishing touches have been applied, it will have a clear finish. I currenly have a Weston Acoustics valve amplifier to test the match. This speaker is intended for valve amplifiers. I'm currently considering making two different crossovers available - depending on whether one intends to use a valve or solid state amp. The valve version would use ferrite cored inductors which have the lowest possible DC resistance, better preserving damping factor and maximising efficiency. The solid state version would use air cored inductors with a slightly higher DC resistance due to the extra copper required. The solid state version might also have more bafflestep compensation.

Surround speakers

Box built. B&C 8PS21 8" woofer + Dayton round 10" waveguide + DE250.

This surround will sit as shown here as there is just one row of seating, this is why the horizontal mounting. There will be a slight vertical tilt down and the off axis response will cause seats near the surround to still image well.

Bitumin rubber box damping has been applied to the box, so it is quite dead. This box is my trial speaker for a finishing method I have in mind, aimed at eliminating butt join seams which always appear when MDF is painted. I'm using layers of fibreglass reinforced auto filler and fibreglass resin. The result is a very hard and durable skin applied to the MDF. It makes painting much more labour intensive!

July 15, 2012

Coming kits ...

1. 6" stand mount kit

Two way passive speaker - bass reflex.
SB Acoustics midwoofer and ring radiator tweeter.
Flat pack with 18mm MDF.
Pre-assembled crossover.
Active crossover option available.
Box and crossover upgrades.

There are a lot of "me too" stand mount speakers out there, but there are two reasons behind this offer. The first is that the demise of LSK has left a void in the market. The second is that I would like to lift the standard of kits. Typical kit offerings have butt jointed MDF, meaning a painted finish won't work well as seams will appear. Veneering is a good choice but ends up with square edges and no attention to baffle edge diffraction. The design I have in mind here allows for a painted front baffle - easily done with a low cost spray can. All other edges can be veneered and there is a groove between the two finishes.

There are options out there for small, cheap speakers. This isn't an attempt to compete with those, but instead it's aimed as competition to higher end speakers.

2. Transmission line floorstanders

Two way passive transmission line.
SB Acoustics midwoofer and ring radiator tweeter.
Flat pack with 18mm MDF.
Pre-assembled crossover.
Active crossover option available.
Box and crossover upgrades.

The transmission line speaker shown here is my most popular page to date. The beauty of a transmission line is that you get the extension of a bass reflex yet the design allows the entire box to be filled, resulting in a very neutral and natural midrange and tight articulate bass.

3. Open baffle kit

High sensitivity design with a hybrid active/passive crossover, neo compression driver with a waveguide, 6" mid and pro woofers.

4. Home Cinema LCR

An Econowave style speaker with a 10" midwoofer, ideally suited to home theatre.

5. Surround

TBA ...

6. 18" HT sub

Home theatre subwoofer with a high excursion 18" sub driver. Intended for use with an external amplifier and DSP.

7. 18" active woofer

TBA ...

July 9, 2012

Assembled upgraded crossovers for JV60

Upgraded crossovers that have been assembled are now available for JV60.

Made to order. Including Jantzen caps, MOX resistors and custom wound air cored inductors.

Compared to the JV60, all parts are better quality. All the parts that aren't needed have been removed. Tweeter Lpad added. Ferrite cored inductors are not suitable for this speaker, so they are replaced with custom wound air cored inductors with AWG 13 copper. That is heavier gauge than just about any inductor you can buy as a standard item.

Contact me if you would like to enquire further or order

July 5, 2012

Loudspeaker kits

Currently considering offering speaker kits, including a flat pack of 18mm MDF, drivers, crossovers and accessories. 

Conventional designs available as a stand mount or floorstander.

It's also possible that I could create designs based around waveguides, compression drivers (or horn loaded ring radiators) and high sensitivity drivers. 

I could offer 3 levels.

Budget kits

These would use good quality drivers that would not be familiar. Don't worry, they wouldn't be junk drivers, but would need to be good value and good quality. They need to be well-behaved drivers because in a budget kit, you can't throw money at too many crossover parts to fix problems. They would also use low cost crossover parts (no electro caps though!)

Mid level kits

These would use more familiar drivers like SB Acoustics, Vifa and Peerless. Crossover parts would also bump the price up a little more, including more familiar name brand parts.

High end kits

My recent poll shows that people are most keen on budget kits, but if the interest is expressed, I can also offer high end kits using high end drivers like Scan Speak, Acoustic Elegance, B&C and the like. The cost would be quite a bit more, but your money is going into better parts.

It's quite likely I'll be developing the budget and mid level kits in the coming weeks. With high end kits however, it will take an order to kick start it.

woofer flat packs

Currently considering offering a flat pack with some efficient 18" pro woofers, ideal to run below horns and also ideal for a very high output dynamic system.

A number of posts back you can see 3 Celestion woofers on offer.

Contact me to express interest

Reverb time

One useful feature of REW is the ability to measure reverb time. Here are 3 rooms compared:

Red: Pixelplay's room with Linkwitz Orions - a large room open to other spaces with glass and bricks, minimal treatment on the rear wall. See room >

Blue: Earle Weston's room at the Melbourne hifi show. A small hotel room with no treatment, concrete floor, carpet and some solid party walls. See room >

Orange: My room with 3 large bass traps and prototype point source horns.

You can see that with my room, the reverb time is lower due to the much larger amount of absorption used and the size of the room. It is consistent with high frequency energy only slightly diminished and the lower midrange starts to drop down, which explains partly why this region sounds very clean and dry, the bass traps are doing a great deal in that region. For the sake of a more consistent reverb time, and in the interests of perfectionism, I might add membranes to the traps. In fact I have done just that since taking this measurement. Some may prefer a little more reverb for a music system, but in a small room it's generally better to have it slightly dead than have a more coloured room. The constant directivity of the horns is also a factor in getting a consistent reverb time - there is less reliance on room reflections and the response is more "speaker dominated."

Earle's show room is more like many will be familiar with, where the midrange is getting more boost from room reflections. Carpet and furnishings are reducing the top end reverb, but aren't thick enough to work lower down, so you see the uneven reverb. Selective treatment in this room could pull down the midrange but preserve the top end. As it stands, it was a bit coloured and for critical longer term listening would need some attention.

Pixelplay's' room shows a similar reverb but at a higher level. The use of a dipole speaker with a reflective front wall is part of what is seen here. The space is open with a mezzanine above and openings to a space behind the room and there is a high ceiling.