View Full Version : FlexiSpeaker

04-27-2015, 03:18 PM
This part of my sound system journey started around 8 years ago. The old 4-ways was too constraining, being a single box. I also wanted to move away from passive crossover, because it changes with drivers and horns.

A plan started to form - design a modular crossover and pick some parts for a 3/4 way system.Back in 07 I was very pleased with my 2245's, so they were definitely in. Along the way Nelson Pass released an article about Slot loaded open baffles (http://www.firstwatt.com/pdf/art_slob.pdf), which were implemented first for my office speakers (http://www.audioheritage.org/vbulletin/showthread.php?33227-A-new-pair-of-computer-speakers-for-the-heavy-user&highlight=). Bass-box was revised into slob's and an extra pair of 2245's aquired.

For mid-bass duty the old 2202A would have to be releaved. I looked at JBL 2020 and Tad TM1201. A pair of Tad's surfaced first. A 130Hz horn was modeled with hornresp.

Mid/high was definitely going to be updated. First I stumbled over a pair of 2435's, and was quite happy with that idea until 4313B sourced me a pair of 476Be. Modeled a 400Hz horn.

I designed a modular fully balanced crossover. It has been fitted with 3-way stereo main-boards. Each main-board can take up to 3 filter-/equalizer- cards.

I first fired the system up in september, with no equalizer cards. Have built equalizer cards during the winter.

Finally I can say that my take on a FlexiSpeaker is up and running. Any component can now be switched with minimal effort. This is a solid platform for continue development.

04-27-2015, 03:21 PM
More pictures

04-28-2015, 10:07 AM
I'd sure like to hear those :)

04-28-2015, 02:35 PM
Wow! You made my day :applaud:

Have you tried current amp on the TM1201 ? (a simple inline resistor of around 20 ohms goes a long way toward current drive for a 8 ohms driver)
It gave me impressive reductions in distortion on mine (not horn loaded), and the modifications of the response also made it simpler to EQ.

Mr. Widget
04-28-2015, 02:39 PM
I'd sure like to hear those :)Yeah! Wow!! Very cool... and I think you need to add some odd metal bits here and there to take the aesthetic design deep into steam punk territory. :bouncy:


04-28-2015, 05:55 PM
Awesome. I love the look. They would look perfect in a nice log cabin. Very nice work. What type of crossover design did you end up using? What are you using for your amps running everything?

Also what is your opinion of the nelson pass slot loaded bass driver configuration? I've been wanting to try that design in a subwoofer.

Again awesome work.


04-28-2015, 11:45 PM
@Pos: Haven't tried current amp yet. It's on the ToTry list.

@NickH: The crossover uses 4-pole Sallen-Key filters. Would you like a detailed writeup on the complete crossover?

Comparing the slob's to a bass-reflex system with similar measurements they feel bass-shy. The room isn't pressurized and they are dead quiet whenever there's no signal. The characteristic would be tight, not fat. They do deliver a ridiculous impact and when fed material with punch you get a serious chest massage.

Regarding placement - they react opposite to bass-reflex systems. More space behind and around gives lower frequency output.

With a pair of 2245's on each side they roll off @25-50Hz depending on placement. Note to self - want to try 4 x 2245 on each side. For sub-woofer duty you might want to use even more drivers.