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Toronto Audio Video Entertainment Show (TAVES 2016)

174.117.243.202

Posted on October 22, 2016 at 04:17:53
Cousin Billy
Manufacturer

Posts: 225
Location: Greater Toronto Area
Joined: September 10, 2004
Contributor
  Since:
October 25, 2015
I suspect very few of you are in Ontario Canada. If you know an audiophile in the Great White North, I'd be honoured if you sent them to the show, October 28-30, Markham Ontario.

I've been building speakers for 8 years. The first 6 saw parallel crossovers. For some reason, I was never fully satisfied with this topology, not with my designs, or any others. The last 2 years I've gone a different route. I started by studying Dual Differential amplifiers. My own MA-1's where the test subjects. What did I learn?

With a Dual Differential amplifier: the positive binding post on the amp pushes the drivers OUT. This is also true of single ended (unbalanced) amps. The negative binding post pulls the drivers All the way back in. With unbalanced this is not true. The negative signal is thrown away (referenced to ground). Words like damping factor are used for single ended amplifiers. They use this word to describe an amplifiers ability to 'correct' its inherent flaw.

There's an obvious flaw with my using the line 'correct its inherent flaw', most speakers don't sound that different with either amplifier, even though we know that Dual Differential should be much better.

I started down a path: what does a capacitor do to the electrical information? I'll use the word 'waveform'.






The blue trace is whats coming out of the DD amplifier. The rising portion manipulated by the positive binding post, the falling portion by the negative binding post.

The purple trace is with a single capacitor in the signal path. This would be a first order parallel crossover. There is a change in the waveform, and we get half the height. Half the height means half the volume (of the transient peak). The total volume is the same, just not as clear or dynamic. This is now an unbalanced signal, even though it came out of a balanced amplifier. My conclusion? Parallel crossovers are the enemy.

In my feeble little mind, I had to simplify what a capacitor is doing.





What happens if we put a capacitor on the positive terminal of a tweeter, and also put one on the negative terminal of the tweeter?






The trick is finding a way of guaranteeing continuity. There are 'cascade' circuits, and for me, 'dual cascade' circuits.





This is not a speaker crossover, its an LCLCLC shunt circuit. I've searched the web, and it appears Evolution Acoustics is moving away from parallel crossovers, and implementing shunts. Read about it in their MM3 Exact literature.

There are a handful of drivers that will work, and so those are the ones I chose.

Now we balance the circuit. No fancy theory. No calculations. Just get the exact same 6 components, and solder.

I have fine tuned the circuit, and may post the exact values later.





If I have to call this a crossover, then it's a Quasi Second Order Series 4-way.

Gauder Acustik calls their symmetrical crossover 'Symetized'.

I have introduced my crossover at a few other websites, and used the word 'Balanced'. Lew has been quick to point out there is no such thing as a balanced crossover.

I'll stop there. This is too much to handle. How does the saying go? The Proof Is In The Pudding.

We will be in room #7216 at TAVES.

There can be only one of two outcomes.
a) I'm delusional. Just another arrogant speaker builder.
b) I've done it. I've cracked the code.

Let the music begin, and let your ears be the judge.

And NO, the circuit will NOT sound the same driven by an unbalanced amplifier.

Bill Laleff
Euphoria Speaker Design
www.euphoriaspeakers.com

 

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