[Bellari EQ570 Analog EQ Measurements]

On 10/6/2021 at 12:20 PM, Langston said:

 

I don't know. : ) I do know about the original product from Aphex called the Aural Exciter, and the Bellari gizmo is likely a simple distillation of it.

 

Don't read past this point if you value your time or sanity. : )

 

Background

The WWII battleships were some of the loudest places on earth occupied by people and they had a terrible time communicating with the crew. Thus they trained the heck out of them to minimize the need, but the need to communicate changes in the theater of action was still there. Sound system power was quite limited at the time, but they found that if they pushed the system pretty hard into distortion (10%+ 3rd harmonic), they could get the equivalent of about 10dB+ louder communication ability without additional voltage from the amplifier or excursion from the compression drivers in those reentrant horns. The clipping amplified the consonants in speech aurally (perception), and it is the consonants that provide understanding (articulation) in speech. It wouldn't be until the 70's that Peutz would develop a speech intelligibility metric he called the Articulation Loss of Consonants (ALCons), but the major ground work had been laid during the war.

 

So. We learned we could make huge apparent increases in communication based power without actual increases in electrical or acoustic power.

 

Radio and the Loudness War

The 80's saw a distinct change in the way music was broadcast over FM. Whereas the earlier decades of radio worked from fairly fixed definitions in broadcast technology and end-user reproduction systems, the 80's saw wild advances in both domains. While the earlier decades had to compete based on content, the 80's had the advantage (?) of maturing processing capabilities that the Beatles pretty much started in the 60's with multitrack and large scale concerts. Thus compression and hard limiting was used by radio to increase the apparent loudness of their transmission, but this initially brought complaints from both record producers and end users. A smart guy at Aphex used the clues in Peutz's work and started clipping audio on purpose and found a range of adding distortion that mimicked the natural harmonics of the bass and midrange in such as way that it highlighted them without actually increasing electrical power dissipation. Thus we tend to perceive more bass and vocal output/clarity even though the actual volume is unchanged. This is exactly what 80's radio wanted because it subjectively offset the heavy handed early compression dullness by "restoring" the liveness of the sound and (perceptually) making it even louder!

 

Of course recording studios applied it to vinyl and tape reproduction formats as both have the same hard limits as radio transmission. Concert sound began experimenting with it as an effect even though they weren't faced with the same headroom limitations. It's in use today via plug-in's in digital recording and concert production, though Aphex still offers the rack mount version. Dave Levine (aka Rat) used it for the Chili Peppers* - he's one of the last of a dying breed that still mixes on analog consoles with outboard racks.

 

2021

What's old is new again.

 

God bless you and your precious family - Langston

 

* Dave became the first and only (AFAIK) FOH engineer for the Red Hot Chili Peppers decades ago when he rented a modest concert system to them in a small venue before they were known. The bassist (Flea) stripped naked during the show and spray painted the mic stands and a bunch of Dave's other stuff yellow! Afterwards, a very not-rich Dave pleads to the group that he can't afford to fix/replace the stuff and the group paid for all the damage. They fell in love with each other that night and have stuck together since then.

 

I believe the Bellari SE560 is more like the BBE Sonic Maximizer. I am somewhat of a fan of the BBE process, I bought the SE560 to try vs a vintage BBE 2002R and 1002. Very simplified (and possibly wrong), the BBE process divides audio into 3 frequency ranges and applies phase change/delay then mixes it all back together.

[Klipsch crossovers]

1 hour ago, radiogram said:

@net-davidIt appears to be the first version as the date is Sep 2005. Could you tell me how to contact Trey Cannon so I can get circa 2009 schematics?

 

Thanks Again

 

Trey was who responded when I contacted Klipsch support through their website, the email was from support@klipsch.com .

[Klipsch crossovers]

2 hours ago, radiogram said:

@net-davidThe other thing I request you is to re-check is the polarity of K53Ti. In CWIII it is reversed compared with Woofer & Tweeter. But not so as per your observation.

 

Thanks

 

 

Sorry, I did not actually check polarity to the drivers, I'll go back and do it.

[Klipsch crossovers]

I did some quick and dirty measurements of my Heresy III's crossover last night and I think I have all of the values now. By quick and dirty I mean I unscrewed the crossover but left all of the drivers connected, I could hear the 1kHz tone my B&K LCR meter uses through the speaker while testing. So I'm not really confident on the inductor values. I'm pretty sure of the C and R values, I got them off of the components. I've left the component numbers from Xsim on the schematic this time so we can discuss them easily. I think the topology is correct, I've gone back and double checked everything.

[Klipsch speaker Impedance curves]

Heresy III, also just the woofer inputs and then just the mid/high inputs.

 

I should probably redo these and keep the axis scaling consistent.

[Klipsch crossovers]

@radiogram, I think the values I have on the diagram are correct, here are the pictures I was working from. I'm not certain measuring the inductors in circuit will work because of the topology, but I'll give it a try. 

[Klipsch crossovers]

I've traced out my Heresy III crossovers from some pictures I took a while back, I guess I'll have to open them back up and try to measure the inductor values. They do seem very similar to the Cornwall III schematics on this thread.