S3 progress

Here is a sneak peek at the S3 throat:

In S2, this aspect wasn't modelled very carefully because I built it manually, using a combination of filling with bog and smoothing with a circular file and sand paper. S3 will be sculpted with a CNC router so it has to be right.

The profile is critical in this design.

I have a couple of goals here:

• avoid diffraction
• create the smoothest possible transition from the exit tube (circular cross section) to the horn where the midrange units come into play (rectangular)
• keep the machining cost sane
• retain constant directivity performance

Cheap self watering pots for sale!

Pickup in Melbourne:

 

$10 each or $100 for all 12.

They work exactly the same as any other you would buy from Bunnings, they are just a whole lot bigger! Made from large plastic drums, 600mm diameter, around half a metre high.

Goto SG38 WNS box sims

This post is in response to this discussion:

My Next horns on SNA >

Tuyen has a Goto woofer in a 360L box originally intended for an Altec driver. I presume a tuning of 35 Hz here.

The Goto woofer has an extremely high BL of 37! As a result it has a very very low Qts of 0.15!

It is indeed a unique driver. This is how it models in the 360L box tuned to 35 Hz (I may be incorrect on the tuning). 

 

The existing box is shown in white. Do you see a problem here? The high Q peak there means that the box is too large, making the vent overly efficient. There is such a thing as "too much motor strength" - more isn't always better. This driver is very unusual, and certainly not intended for a box like this. The sensitivity is ultra high, but to get any extension out of this driver, some of it will have to be shedded. The blue line shows the same box sealed - no extension at all, however, in a small cavernous room it could actually have more extension than you think. The red line shows a more suitable box - 60L tuned to 40 Hz. In a room with lots of modes, this could work out. 

Here is the group delay:

 Notice how the large box has an ultra high group delay? It occurs are low frequencies, so it may not be an issue with most music, but this gives us a window to a problem, indicating a poor match.

FS: Aura 18" sub drivers

Quick heads up - some very nice Aura 18" subs currently listed on StereoNET:

SNA listing >

(No, these aren't mine)

From memory, they retail for about $900 each in the US, so they are a lot cheaper here. Located in Melbourne.

Bacon

This one is for Earle Weston of Weston Acoustics ...

Melbourne music spotlight: Stewart Kohinga

Ever noticed how much mediocre music lives on the radio, regardless of the channel? Well, in the interests of promoting musis that is actually worth hearing, that you might not hear on the radio, let me introduce some local talent. Stewart Kohinga is Melbourne singer and songwriter who recently performed live as part of the Live at Baker street series.

I would describe his music in poetic terms, but you can hear it for yourself on youtube >

Stewart Kohinga online:

Facebook page
Website

Live at Baker Street series >

RSA HE2 finishing ...