What is threshold on the 1632c crossover

[Brek]

Can someone explain what the threshold control does on the 1632 crossover in laymen terms. It's control in DB and doesn't seem to change the sound.
http://alteclansingunofficial.nlenet...32C-Manual.pdf

[Todd W. White]

The 1632A (there was never a B or a C - I'll change that typo as quick as I can - sorry), of which I have installed many, is an electronic crossover with built-in limiters on the output.

In live sound reinforcement systems, you set the threshold level so it stops the system volume level from going past the maximum volume level you want the system to go.

In other words, you calibrate your sysem so that the limit feature kicks in before the amps clip, presuming, of course, you've set up the rest of the system, including the amps, properly.

The reason you don't hear it functioning is because Altec used a patented feed-forward design in the circuitry that eliminated the pumping heard in ordinary compressors.

[Brek]

Thanks for the fast reply.
So, I can just leave it on the max setting?
Would it be useful for horn protection?

[bfish]

On your 1632, each output has a built-in limiter, and those threshold controls allow you to set the level that the limiter for each output "kicks in", kind of like an additional volume control that works from the top down.There are also switch settings inside the 1632 that allow you to control how fast each limter reacts in ms. This is all described in detail in the 1632 manual, beginning at section 5.5.

Ideally, a custom biamped system should be initially setup using an RTA and a voltmeter. Without these tools, or at least a fair amount of experience setting up such systems, it's very difficult to get everything set correctly. For home system setup without an RTA and voltmeter, I'd start with the threshold settings at their lowest, only increasing them to the point of what you would consider a comfortable setting for max volume. This could help protect your drivers if others beside yourself can access the master volume controls. If, however, your amplifiers are well-matched to their respective loads, you might not need to use the limiters at all.

[Brek]

I'm running a 9442a for the high end. So maybe I need the limiters to protect the horns. I do have the outputs in the back turned down.

I'm just a novice playing around with bi-amping my Santiagos. I'm running a Ab international 270wpc for the low end.

Probably too much power for the drivers, but it sounds great.

[bfish]

With that amp/driver combination, you won't have to worry about the amps clipping, as the voice coils would be melted down long before you reached that point. Your power allotment of 270/100 is relatively in correct proportion to the driver ratings of 60/30, but you obviously will want to limit continuous power to about a third of what you have available. I'd stay with the recommended 800Hz XO point. You might also want to remove any EQ submodules from the HF sections since you're not using a CD horn, and setup the 30Hz high pass filter in the LF sections, especially if you use a turntable/vynyl.

Welcome to the biamp world! I think you'll really like it, as the Santiagos are an ideal candidate.

[Brek]

So, could I limit the power to a third by simply setting the thresholds one/third up?

I was listening to some classical a while ago with the threshold turned all the way down, like you suggested. On some loud passages, the limiter lights started flashing. So I ended up setting them at about one third up before they settled down.

This wasn't even as loud as I sometimes listen to it. I like concert levels on some of these fine recordings, like some Telarc. Am I risking my drivers with short dynamic bursts?

Will the threshold controls limit the watts to the drivers, without effecting the sound?

[LICORNE]

Hi,
I'll let the other guy respond to your question.
But i just want to explain that your limiter is like a compressor. The 806B is rated at 15 watts.
Peak? probably 50.

I wouldn't worry about peak passages on clasicals.
Just set the treshhold so it peaks loud but not extra loud for a long time.

......................................

[Animal 1954]

Hello, What is the difference between the 1631 and the 1632? Are the xover diodes interchangeable? Thanks for the reply,Roger

[bfish]

Brek,

"So, could I limit the power to a third by simply setting the thresholds one/third up?"

****Unfortuneately, it isn't that simple, as the gain settings on the 1632 and the amps all come into play interactively. For the trial-and-error setup method, starting out low is the safe way.

"I was listening to some classical a while ago with the threshold turned all the way down, like you suggested. On some loud passages, the limiter lights started flashing. So I ended up setting them at about one third up before they settled down."

***Which limiters flashed, low, high, or both? I'd recommend ensuring that the internal response time selectors were all set to "medium" to start with. This will prevent the limiter being activated by individual LF cycles.

"This wasn't even as loud as I sometimes listen to it. I like concert levels on some of these fine recordings, like some Telarc. Am I risking my drivers with short dynamic bursts?"

***If you've been using your Santiagos with a passive XO, you can safely run them biamped at or slightly above the levels you are used to. The steeper slope of the active XO actually allows for higher levels than passive (the Santiago is rated for 60W total as passive, or 60/30 as active). Accurate absolute maximum levels can only be safely set via measurement with test equipment. Short dynamic transients can safely exceed rated driver levels without causing damage.

"Will the threshold controls limit the watts to the drivers, without effecting the sound? "

***Yes, if correctly setup, up to maximum allowable gain settings.

Specs from Altec's biamped Santiago, the 2878B;

http://www.lansingheritage.org/image...iago/page2.jpg