mid freq responce

[vnzbd]

I am looking for an education of what determines a mid freq responce. I know that the crossover will limit the freq that the mid will see but am curious on what determines the mids limits. I have a set of quartets that I will be updating the caps and tweeter diaphrams and am curious about doing the mids diaphrams at the same time. Bob Crites and Klipsch sell thier versions and those are the options that I would consider. The Q's mid runs from 650-7k hz.

Does the diaphram have any impact on the frequency range of the mid?

How does the horn play into freq responce?

Does the diaphram have any impact on the sensitivity of the driver?

Thanks

[Guest " "]

in general a mid driver is controlled thru a band pass filter which consists of a hi pass filter in the form of a capacitor for the low end of the frequency band and a low pass in the form of an inductor for the high end of the frequency band.

[Ski Bum]

Does the diaphram have any impact on the frequency range of the mid?

Not sure if the diaphragm is responsible, but as an example, the phenolic mid in your Quartet rolls off naturally above 6 KHz, where the Klipsch ti mid (the K73?) response extends well above that. Bob Crites has mods that specifically address that, if you decide to upgrade your mids too. I'm not sure you need to, as the cost and hassle are more than the simple cap/tweet upgrades, which are a great bang/buck improvement.

How does the horn play into freq responce?

I think the more important factor is how directional it is, at the low end of it's range as compared to the woof, and at the top as compared to the tweet. The driver will be operating in the lower end of it's operational range, so distortion will be low, and I won't go into horn induced colorations, as they have never gotten between me and the music.

Does the diaphram have any impact on the sensitivity of the driver?

I asked Bob this, and he said no, which kind of surprised me. I would think that if the mass of the diaphragm is reduced, sensitivity would increase. Maybe his ti tweet diaphragms are the same mass as the polys they replaced, I don't know. (I have forte II w/ Crites full crossover and ti tweets.)

Bob frequents this forum, maybe he'll chip in. If not, you can always call him directly. He's a pleasure to deal with.

[Greg Oshiro]

If you're comfortable with math, find a copy of "Acoustics" by Leo Beranek. The real answers to your questions are not simple, but in brief:

<snip> Does the diaphram have any impact on the frequency range of the mid?<snip>

Yes. Lower diaphragm mass will generally provide more high frequency output, provided other things are done correctly. Stiffer diaphragm material generally provides more high frequency output.

<snip> How does the horn play into freq responce?<snip>

It's really the interaction between the horn and driver (including the diaphragm) that determine the low frequency corner, high frequency corner, distortion, dispersion pattern and everything else

<snip> Does the diaphram have any impact on the sensitivity of the driver?<snip>

I believe that lower diaphragm mass increases the sensitivity. I don't have my copy of Berank's book at hand, so you'll have to look it up and let us know

[DavidF]

I am looking for an education of what determines a mid freq responce. I know that the crossover will limit the freq that the mid will see but am curious on what determines the mids limits. I have a set of quartets that I will be updating the caps and tweeter diaphrams and am curious about doing the mids diaphrams at the same time. Bob Crites and Klipsch sell thier versions and those are the options that I would consider. The Q's mid runs from 650-7k hz.

Does the diaphram have any impact on the frequency range of the mid?

How does the horn play into freq responce?

Does the diaphram have any impact on the sensitivity of the driver?

Thanks

The gist of your questions may be what to expect if you go with different diaphragms for the mids.

Different diaphragms will have differing frequency responses, yes. So the question then is how much of a difference? I have not seen comparative response curves or heard, say Bob’s diaphragms v. stock, to state how much.

The horn does play into the frequency response certainly. The frequency response output is a combination of the driver’s response and the horn’s effect on response. Horn systems that extend down to 1k Hz or so typically roll off around 5 or 6k. As frequency rises the mass of the driver reacts with the horn’s resistance to roll off response by 6bB on average. Different drivers will have different characteristics in combination with the driver and horn. I find that the Klipsch K61 mid will show roll-on roll-off “knees” in response at about 900Hz and 5k Hz.

I don’t know how the different specs of a diaphragm will alter the sensitivity in a given driver/horn combo. I suspect not much for practical purposes and would not be concerned about it in swapping diaphragms as you are considering.

The stock midrange Forte xover (as an example) uses minimal electrical filtering and instead relies heavily on the acoustic response of the horn/driver for response filtering. Therefore a change in diaphragms could have a noticable effect on response but whether the result is a negative, positive or otherwise I will have to let those who have used them answer this question for you.