Distant cousins?

I’ve showed off my fascination with (small) coaxial loudspeaker drivers before and recently I scratched the itch again with a pair of SB12PACR25-4-COAX.

This is a new driver from the “cheap” SB PFC/PAC lines. Like the Seas driver it has an alu cone and a softdome tweeter, but the price is around 1/3 of the Seas driver, courtesy of cheaper SB manufacturing and a cheaper plastic basket compared to the die-cast aluminium on the Seas. That said, it doesn’t feel that cheap to be honest, because even though the basket is plastic it seems well-made and solid. I have several others of these PFC/PAC SB drivers and they as well-engineered as the rest of the SB lineup IMO and excellent value for money. In case you doubt their “audiophile credentials”, there is even a Troels Gravesen design based solely on the PFC-drivers.

Now I could have just bought the paper-coned version of the coax-driver that has been on the market for years, but I have the 16cm version of that already, the price was about the same and I thought it would be fun to compare the alu-version to the Seas L12 – oh, and I think the alu-version looks cooler as well :).

This is one of the drivers that I have bought with a specific project in mind, namely to try and build a small active all-in-one “desktop” speaker. The original plan for that was a three-way design with a small built-in subwoofer, but the enclosure ended up being very large and impractical (i.e. desk-sized instead of for desk use…). Two of these SB12s plus some electronics is an altogether more reasonable size, so I have repurposed the other drivers for something else instead.

I’ve already cut some wood for the basic design and with a holiday coming up soon, I hope in a week or so I can get these drivers into cabinets and do some basic listening tests. In parallel I am also looking for suitable electronics, but that’s a story for another time (mostly because it’s not done yet 😉 )

Collateral damage…

The weather isn’t really supportive of indoor activities at the moment, so not much building going on. When the sun shines in Denmark you have to make the most of it, so I try to prioritise outdoor activities instead :). However, it’s always good to make plans for what to do indoors when the weather changes…

As mentioned in the previous post I have been online-shopping for interesting power amp designs lately. I managed to find a few, but as usual when I look for PCBs I don’t just find what I need but also – inevitably – a few things I didn’t know I needed 😉

One of those finds this time was a Pass (-inspired) preamp board. It’s a complementary design with IRF610/IRF9610s and switchable gain fed from a single 60V power supply rail. I’m not sure if this is really a genuine Pass-circuit (at least it’s not one I immediately recognize). However, it looked interesting and I had most of the key parts available already so I decided to take the plunge anyway.

A few bits and pieces missing still, but it shouldn’t be long before I know if the board was worth the investment…