Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Kingston Eck]

Hello All!

First, I was not sure if I should post this here or in the Basement or the Lounge, so if a mod thinks it should be moved, please do so...

Here is the scoop, I recently purchased 4 unloaded LABs to replace two very old and decaying labs.  I had two spare lab12s lying around, so I bought another set... and holy crap!  I now need more tops... lots more tops!

As a graduate student in engineering I have some flexibility with my scheduling.  This semester I had a great idea, and talked the Dean into approving it.  I am taking 25% of my credit hours this semester doing an independent design study of horn loudspeaker design.  I am studying under a professor who's interests lie in acoustics, so he will be helping with ideas as well.  Basically I am doing research, modeling and hopefully some prototype testing on horn loaded enclosures for the subs I recently acquired.

This post is basically me wanting to bounce some ideas off of the people that would know way more than what I do and have better judgment than I would by doing research alone.  Right now I am doing some modeling in Horn Response and doing lots of reading, later I plan on making 3D models of the designs and plugging them into the FEA program ANSYS to better evaluate them before building a prototype.  As of right now I am just trying to nail down parameters to shoot for as far as frequency response, so any input into what anyone here would consider an ideal response would be awesome!

The first and most needed addition is more midbass!  Playing around with the LABs, I tend to like the crossover set around 80-85 hz, maybe 90, but no higher.  So, I figure I am going to want a midbass horn with decent response to 60-70 hz... does this sound about right?  I figure if they had solid response to 70 and I used steep filters everything would work out in the end.  I am not sure how high I should try to go with them, I figure 3 octaves or so, especially if I try to build a curved horn.  That would put the midrange horn kicking in around 400-500 hz or so, which seems pretty doable...  I figure the midrange and tweeter would be in the same enclosure, with separate midbass and subs.

So, how is this sounding so far?  Should I start doing more design on the horn with response to 70hz or anyone think I should go lower?  Any and all comments and criticisms will be accepted, just don't flame me too hard!  I am trying to learn a lot from this project!  Thanks guys, and sorry the the long post!

Kingston Eck

[Art Welter]

Kingston Eck wrote on Tue, 22 September 2009 20:27

The first and most needed addition is more midbass!  Playing around with the LABs, I tend to like the crossover set around 80-85 hz, maybe 90, but no higher.  So, I figure I am going to want a midbass horn with decent response to 60-70 hz... does this sound about right?  I figure if they had solid response to 70 and I used steep filters everything would work out in the end.  I am not sure how high I should try to go with them, I figure 3 octaves or so, especially if I try to build a curved horn.  That would put the midrange horn kicking in around 400-500 hz or so, which seems pretty doable...  I figure the midrange and tweeter would be in the same enclosure, with separate midbass and subs. So, how is this sounding so far?  Should I start doing more design on the horn with response to 70hz or anyone think I should go lower?  Any and all comments and criticisms will be accepted, just don't flame me too hard!  I am trying to learn a lot from this project!  Thanks guys, and sorry the the long post! Kingston Eck

Kingston,

A decade is reasonable for a horn, 60-600, 80-800 HZ,etc.
You won't be breaking any new ground, the low mid decade is pretty easy to do.

You won't need the mid bass to go as low as you might think because the acoustical overlap of the LF will often compensate for the MF roll off.

Directional MF horns when coupled will have a lower corner frequency.

Have fun.

Art Welter

[Kingston Eck]

Art,

Thanks for the reply!  I am not looking to do anything groundbreaking or monumental.  The project is more to learn about horn design, as I really would love to know more.  I have done reading and a little bit of experimentation in the past, but this project and the fact that I have more subs is a driving force behind really learning a lot more about the theoretical and practical aspects of the subject, including building some prototypes and doing measurements and comparing the actual performance to that which is anticipated from the design work.  That is one nice thing about my program I am in, the students can customize their studies to what interests them.  The other advantage is that I will get some decent sounding boxes (hopefully) to use for SR work.

So you are saying that 70 would be lower than needed?  I am wanting to obviously go as high as possible on the cut off on the midbass to minimize the overall enclosure size. What would be reasonable?  80 or 90hz?

Also, would a decade (80-800) sound OK out of a folded horn?  I am thinking a folded horn would be much more practical than a straight horn.  I am planning on making any bends curved, but I have read a lot of negatives against folding a midbass horn if it is going to be used higher than a few hundred hertz...  My computer crapped out last week, so I haven't had much time to play around with the designs yet, but hopefully this week sometime I can post some simulations and models and get some opinions.  Thanks again!

Kingston Eck

[Marjan Milosevic]

Folded horn would not go up to 800Hz. 400/450 at the best and that is if you can find a suitable driver with a super light cone. As i can see from the present products there is just Funktion One that has a box like that and that is with a very special driver.

[Art Welter]

Kingston Eck wrote on Sun, 27 September 2009 22:17

So you are saying that 70 would be lower than needed?  I am wanting to obviously go as high as possible on the cut off on the midbass to minimize the overall enclosure size. What would be reasonable?  80 or 90hz? Also, would a decade (80-800) sound OK out of a folded horn?  I am thinking a folded horn would be much more practical than a straight horn.  I am planning on making any bends curved, but I have read a lot of negatives against folding a midbass horn if it is going to be used higher than a few hundred hertz... Kingston Eck

Your subs are 45 inches deep. A straight horn that deep will go well below 70 HZ. I am presently using a straight conical horn about 28" deep with 8" speakers from 80 to around 900 HZ.

LF behave more like laminar flow while HF behaves like a ray of light.

Curved bends are not the best way to fold mid and HF, and are not needed for LF.
Look at the EV mid and high manifolds to get an idea of how to fold, if you want to fold for depth reduction.

[Dan Magers]

Art Welter wrote on Tue, 29 September 2009 12:51

Kingston Eck wrote on Sun, 27 September 2009 22:17 So you are saying that 70 would be lower than needed?  I am wanting to obviously go as high as possible on the cut off on the midbass to minimize the overall enclosure size. What would be reasonable?  80 or 90hz? Also, would a decade (80-800) sound OK out of a folded horn?  I am thinking a folded horn would be much more practical than a straight horn.  I am planning on making any bends curved, but I have read a lot of negatives against folding a midbass horn if it is going to be used higher than a few hundred hertz... Kingston Eck Your subs are 45 inches deep. A straight horn that deep will go well below 70 HZ. I am presently using a straight conical horn about 28" deep with 8" speakers from 80 to around 900 HZ. LF behave more like laminar flow while HF behaves like a ray of light. Curved bends are not the best way to fold mid and HF, and are not needed for LF. Look at the EV mid and high manifolds to get an idea of how to fold, if you want to fold for depth reduction.

Art, What happened to your Alpha loaded line array?

[Art Welter]

The line array is going strong.
On shows where I need more low mid output I put a 15 inch deep 90 degree wave guide extension in front, which doubles the mouth area and lowers the horn cut off.

A few sheets of plywood for a 3 dB gain.