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Henry8 22nd July 2010 12:40 PM

setting up levels on a three way active system
Any one experianced in measuring and setting the output levels.?
Ive set the tweeter and mid drivers levels with farfield acoustic tests at about 0.7M.
The question is how to set the bass drivers levels, of which there are two wired in series in a common box.

bentoronto 22nd July 2010 02:03 PM

Think you might wish to share with us what your configuration is? A big box with two L-pads on the back? Bi-amped? Tri-amped? EQ?

Naturally, I check the flatness and cleanness of electronics with some care as far down the circuit as I can... to the speaker terminals if they are showing (exception is ESLs, of course). A Denon test-tone CD gives me a CD-to-oscilloscope complete system picture. For sure, you want to confirm your cross-over channels are tracking and otherwise identical.

But I have never found any instrumentation at all useful for final acoustic tune-up except for a bass sweep tone band I've been listening to for 53 years. I also have some pet recordings - like with bells or music boxes - that tell me pretty fast what my tweeter level is doing.

Robh3606 22nd July 2010 04:11 PM

Be good to know where your crossover point is. For example in you are the 700Hz region you can do what you have been doing. You need to set the crossover for the optimum transition between drivers. The room effects on the bass are secondary. Get the transition right and the rest should fall right into place.


Henry8 22nd July 2010 05:01 PM

The bass-mid xover freq is 260Hz, and the gating limits usable freq resp data to about 500Hz at most

Robh3606 22nd July 2010 05:25 PM

OK that doesn't help. Can you run pink noise and have an RTA available?? I have a couple of biamp set-ups crossed at 300hz I use an RTA to set levels with. It works well enough and you should be able to get close using program material.


Henry8 22nd July 2010 08:38 PM

This is the same as doing a ungated resp test, which includes room effects, which make setting levels impossible.

Pano 22nd July 2010 09:01 PM

Why? Do you not hear the room, too? It counts in the overall level.
One caveat, your ears are not omni directional, so take that into account when using an omni mic.

Robh3606 23rd July 2010 12:12 AM

1 Attachment(s)

This is the same as doing a ungated resp test, which includes room effects, which make setting levels impossible.
Why don't you try it. You are using random noise not a sine sweep. Here's how my 4344's look with the room effects in an RTA measurement. Really easy to set the levels using it.


Conrad Hoffman 23rd July 2010 02:31 AM

I'm a huge believer in measurement- I use it right up to the point where I have to listen to music. Then, it's all ears. I have a level control on my active crossover for lo, mid and high. One of them will always end up at max, so I start with everything at max and just tune two of them down from there with a variety of music. Naturally it's not that simple because I also moved the crossover points somewhat, not to mention moving the speakers around. Though I don't believe in "time alignment", I do believe in directionality caused by the location of the tweeter. IMO, being able to move the tweeter in and out by a few inches is highly valuable. To get really happy with the system probably took a good few months of fine tuning. (I did do some sweeps to be sure nothing was wildly wrong. In the past I've used third octave measurements, but concluded I just don't like flat response.)

bentoronto 23rd July 2010 03:13 AM

All my sentiments too but I'll say it is a wise post anyway.

Why do you suppose microphone flat is not perceptual flat? Or are we talking about mic flat versus personal joy?

Footnote: after I diddle with the many crossover parameters on my Behringer CX3400, I like to fine-tune the knob settings by meter. Otherwise, there might be some irregularities and it is never feasible (or possible) to sort them out by ear after.

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