If you were to make an educated guess, how many decibels down would the addition of each speaker unit(or group of 2 or 3 units) would the distortion levels go. Would you expect that for each unit the distortion would drop one decibel, so for 9 of them the level would drop 9 decibels?

Jim Muro

I have read all the reviews I could find on Fountek ribbon based line arrays. I know you are thoroughly familiar with several of these designs. I have not found a single negative comment about distortion or sound quality from these tweeters, only glowing reviews about their sound. I was hoping for an answer approximating “distortion from an 8 tweeter array will be {insert equation and result here} less than a single tweeter operating at the same total output level.”

It appears that my desire to easily eliminating tweeters based on distortion and cross-over points is not viable.

Thanks,
Dave

I have no doubt that I would be astonished by the sound quality of your arrays. Your suggestion on multiple crossover frequencies based on different listening situations is quite clever. I plan to try multiple crossover configurations. It is a great idea to test them at different output levels and save the different configurations that work for different settings. You didn’t answer my question about audible distortion on the PT2B’s. I was hoping for an answer approximating “distortion is completely inaudible on low to mid level playback, but becomes slightly audible when I twist the volume knob to 11.”

I was hoping to find the perfect tweeter using objective measuring. I am going to have to take your advice and buy sample drivers and do my own listening tests. I would concur with your “progression” observation in the DIY kit market, but I still can’t tell why this is the case. I have the feeling that this narrow range of product selection is based on extensive subjective listening tests by a few experts in the array building field.

Thanks,
Dave

>>"...For example you can successfully cross the Fountek Neo2.0 and A-C G3 ribbons as low as 1500 Hz in lines of 8 or 9 devices without audible distortion for home listening conditions..."

THIS IS EXACTLY WHAT I WANTED TO KNOW! I can not thank you enough for your response.

Dave

The ribbons and planars do exhibit audible distortion if pushed too low or the low end response isn't properly shaped. Slopes that are too shallow can also create problems.

1. Eight PT2 = ~ $200
2. Eightteen BG Neo3 = ~ $700
3. Eight Fountek NeoCD2.0 = ~$950

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If you call Madisound and order 16 of the NeoCD2.0, you should be able to get them for about $95 each (x 8) = $760 per side.

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I've been trying to figure this out as well. I think that cone/dome drivers in an array would have the distortion drop for two reasons - the sensitivity of the array increased (from multiple drivers) and the reduced drive signal going to each driver.

For the sensitivity portion:
- one driver = (X)dB of distortion (pick whatever harmonic you'd like).
- two drivers = (X-3)dB of distortion (two drivers are 3dB more efficient, so they need to be driven with 3dB less signal to achieve the same level
- four drivers = (X-6)dB of distortion
- eight drivers = (X-9)dB of distortion
- nine drivers = (X-9.5)dB of distortion
- twelve drivers = (X-10.8)dB of distortion
- sixteen drivers = (X-12)dB of distortion

With a ribbon array, you would have the reduced signal going to each individual ribbon, but the array sensitivity remains the same as one driver.

If you have an array of cone/dome drivers, you have the benefit of reduced signal PLUS the sensitivity increase.

I know that distortion increases as drive level increases (and not linearly). This makes me think that you have an increasing benefit as you continue to add drivers to an array.

Can someone help me work through this theory?