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Thread: Setting Tri-amp Volume Levels..., How Do You Do It?

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    Setting Tri-amp Volume Levels..., How Do You Do It?

    What is the typical procedure used for setting the speaker levels for a tri-amp set-up?

    Do you set all speakers to the same volume using pink noise, or do you roll off the upper drivers a bit? (The 604's seem bright setting the same volume to the woofer and horn.)

    What weighting is used?

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    Administrator Mr. Widget's Avatar
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    There are probably a million ways to get there. I start out by getting the levels close to right sounding by ear, then I bring out the test gear and get it as close to flat as possible with a slight downward tilt from 100Hz out to 20KzHz. Ultimately, while listening to a wide selection of music I tweak to taste.


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    Quote Originally Posted by Mr. Widget View Post
    There are probably a million ways to get there. I start out by getting the levels close to right sounding by ear, then I bring out the test gear and get it as close to flat as possible with a slight downward tilt from 100Hz out to 20KzHz. Ultimately, while listening to a wide selection of music I tweak to taste.


    Widget
    Do you use "A" weighting?

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by toddalin View Post
    Do you use "A" weighting?
    I don't use an SPL meter, so no, I do not use A weighting. If you do the result will be far too much bass, since the bass is significantly rolled off with an A weighting, C is closer to flat.

    I use sinusoidal or MLS measurements, for critical measurements I prefer gated MLS measurements.


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    Quote Originally Posted by toddalin View Post
    What is the typical procedure used for setting the speaker levels for a tri-amp set-up?

    Do you set all speakers to the same volume using pink noise, or do you roll off the upper drivers a bit? (The 604's seem bright setting the same volume to the woofer and horn.)

    What weighting is used?
    Did you replace the passive with a line level crossover? If so, the horn will be vastly more efficient. It should be on the order of 12+dB lower amp level than the woofer. The passive XOs have a lot of padding.

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    Administrator Robh3606's Avatar
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    Why are you using an SPL meter?? The exact levels don't matter just the relative between drivers. Just use your RTA with pink noise.

    Rob
    "I could be arguing in my spare time"

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    Quote Originally Posted by Mr. Widget View Post
    I don't use an SPL meter, so no, I do not use A weighting. If you do the result will be far too much bass, since the bass is significantly rolled off with an A weighting, C is closer to flat.

    I use sinusoidal or MLS measurements, for critical measurements I prefer gated MLS measurements.


    Widget
    I used "C" weighting and found the bass a bit thin. With "A" weighting the aux woofer is way down in the reported volume but it is right up there with "C" weighting. "A" or "C" makes no difference for the horn though (about as expected). Too bad none of my devices have "B" weighting.

    Thanks

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    Quote Originally Posted by badman View Post
    Did you replace the passive with a line level crossover? If so, the horn will be vastly more efficient. It should be on the order of 12+dB lower amp level than the woofer. The passive XOs have a lot of padding.
    Tri-amped Altec Super Big Reds with no passive networks from the get go.

    It is interesting that I have to turn the volume on the crossover nearly full up for the horns (and aux woofers), running from a more powerful amp than the woofers, to get them to balance. My assumption here is that the electronic crossover (obviously a "one-off" most likely created by The Mastering Labs) has been purposely padded down for the horn's output to make full use of it's volume control.



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    Quote Originally Posted by Robh3606 View Post
    Why are you using an SPL meter?? The exact levels don't matter just the relative between drivers. Just use your RTA with pink noise.

    Rob
    Was just a "first attempt" and that is the next step. It is harder to do than my main system where the Behringer provides a continual source of pink noise. In this case I use the Audiophile Test disk ("Thank you Ralph. Now for some pink noise."), so the pink noise only runs for about a minute or two before having to go back and reset it (PITA).

    I will probably disconnect the SACD from the Marantz and run the "Tape out" from the Yamaha (that includes the Behringer) into this input so that I can get a continual pink noise source.

    BTW, the test disk provides both uncorrelated and correlated pink noise. Anyone who has run correlated pink noise through both channels simultaneously (e.g., the Behringer), with an RTA engaged knows the pitfalls and futility of doing this. Each channel must be done independantly.

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    CSN&Y Guinevere on the Tri-amped Big Red Supers.
    Custom One-off Electronic Crossover
    Custom One-Off Passive eq for the Horns
    Marantz 1180DC console
    Marantz 170DC amps (2)
    Yamaha S-2300 Universal Player
    This is a regular CD.
    This is my first attempt at setting the electronic crossover levels and may be a bit "bright."
    https://youtu.be/4MWmYYV1bg4

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    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by toddalin View Post
    What is the typical procedure used for setting the speaker levels for a tri-amp set-up?

    Do you set all speakers to the same volume using pink noise, or do you roll off the upper drivers a bit? (The 604's seem bright setting the same volume to the woofer and horn.)

    What weighting is used?
    You will find the dispersion (power response) of the 604 horn a contributing factor to the tonal balance.
    I would leave it level unless you understand the impact of the power response.

    About the level setting of the horn simply set the woofer and horn level separately using pink noise then reverse the phase of the horn and carefully adjust for the deepest uniform null at the crossover point.

    Once adjusted put back to the normal phase for this driver. The levels should be then should matched be within 1 db.

    You also have to appreciate these drivers are meant to be played loud. The loudness effect at low levels will bias you subjective perceptions of the balance with the horn and the woofer.

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    Thanks guys.

    Did some adjustments to bring up the woofers a bit. Video does not convey the actual level of deep bass felt in the room.

    https://youtu.be/jsPePauUaLo

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    I really do strongly recommend you pick up a more robust measurement system. Last night I built out a new system of crossover and shaping for an active 3 way setup (dual 12" subs, 15" midbass, horn) and was able to do so on the fly- took me about an hour to achieve a smooth downward sloping house curve with very good constant directivity performance. It was done with a DBX Venu360 (which lets you adjust XOs and EQ on the fly) and a continual sine sweep measured by Omnimic. Easy as pie, and with much better resolution than an RTA or SPL meter.

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    The Behringer provided the a nice downward curve and I tweaked the low bass up a couple dB from there. At this point, I have a professional noise level meter ($3K) and I can tweak each side's components to within 0.1 dB of the other side to get a near perfect balance.

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    Quote Originally Posted by badman View Post
    I really do strongly recommend you pick up a more robust measurement system. Last night I built out a new system of crossover and shaping for an active 3 way setup (dual 12" subs, 15" midbass, horn) and was able to do so on the fly- took me about an hour to achieve a smooth downward sloping house curve with very good constant directivity performance. It was done with a DBX Venu360 (which lets you adjust XOs and EQ on the fly) and a continual sine sweep measured by Omnimic. Easy as pie, and with much better resolution than an RTA or SPL meter.
    100% agreed.
    Accurate crossover building cannot be done without reliable magnitude *and* phase measurements, and that is something an RTA simply cannot do, however expensive and precise it might be.
    toddalin, if you like real time tools then smaart might be worth looking at.

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