3 way HORN top

Posted this over on SP but didnt get nything very useful in response. ive just coppied and pasted, so sorry if you have already read this. its helpful to me, and at best it may be an interesting debate to others.......

ive been working on something i think is interesting. ill upload all the plans once its a little more refined, but im working on a long project which i think might be interesting for us all,and would definetly benifit from the expert opinions which float around here.

the design is based around a tms style 10inch mid horn. this is good for about 300 to 3 k. i think mikeys xt8 would be a good alternative, although im not sure what driver to use with it. i had alot of trouble finding a 10 inch driver which would play high enough to meet a beyma 1 inch comp (the PM4 diafram, my new fave). i wanted as smoother highs and high mids as possible, with 133+db efficiency possible.

anyway thats all done realy, but what ive been working on was the low horn. i wanted something which could keep up in a single, be quite small and play down to 100hz

what ive been working on is a reflex assisted straight BPH. ive managed to get over 103db between 90hz and 300hz, and very small. my questions are in relations to this part. its a little like the old altec horns, but with a band pass chamber, which leaves me with nothing to compare with.

i understand i cant have the port opening into the banpass chamber (or can i) which leads me the the question of where. should i have toe port exits at the same point as the horn mouth, and also am i going to have nushy kick because of this.

i dont realy know what questiobs i chould be asking, but realy im just wondering y is this not often used. am i looking at phase soup? the hornresp plots look great. very flat (no more than 30 degrees variation amd the upper and lower limits are in exactly the same phase with the right delay, and the gd goes nuts at the port tune frequency, but that should be easy enough to fix with the dsp.

anyway what are your thoughts?

ill post up more data. it just seems too good to be true. everything just looks great, and i wonder y this is not used in more designs

cheers
Dave

I know this may not be so intersting to you guys, as theirs not been much intrest, but i would love to hear some expert opinions. i plan on going ahead with this and i dont have money to burn on failed prototypes. especialy if its for some reason which experience could have eliminated at the drawing board. for what its worth, this plan will be shared in the publc domain.

thanks

Hello Dave,

Your project is interesting. Let me give you some quick help:

1/ HF
CD10 is a good choice even with the small problem (rigging) at 6khz. PM4 (Polymer) is a very modern material with top performance acoustic properties. I did myself a HF driver based on similar material (300C grade from Dupont Teijin, Japan) and the sound is amazing. This section should have no issue

2/ Mid
Well, to make it very good, you need a 10" driver with inverted dustcap and shallow cone, then your phase plug can follow the curve of the dustcap to reach high frequency response and best efficiency. Unfortunately, to my knowledge, very few commercial drivers are available. I only see 18Sound 6MNB420 but it's a 6" model and it doesn't go as low as you want.

3/ Bass
You idea looks correct. Straight horn will avoid honkyness but be careful of the assisted part because it can mess your phase (then "speed") and it will make difficult to integrate with the sub.


By the way, where are you based ? Maybe I can provide you a custom made 10" driver to fit your design smiley1

Cheers
Arthur

Arthur, you could be a double for Mr Bean. I actually thought it was him standing next to those speakers in your avatar

hi
thanks for the comments.

thanks for the offer on the driver, but at this stage i dont think im in the market for a custom driver. the 18sound im using was expensive enough as it is.

im going to re mould the back of the Phase plug to follow the curve of the new driver and dust cap. to get good high frequency sims have shown me that i need a realy realy small volume in the chamber. ill see how close to optimal i can get.

what i am still realy confused about is the assisted part on the lows. i can manage to get quite a flat phase responce through the band im aiming at (90/100 to 300), but the delay goes nuts. i dont have the sims up right now, but from memory its like 10ms, at around 90 hz. im guessing that with the right delay and a realy steep cut on the filter it might be ok to integrate with subs. what do you think. i was also quite woried as to how the port and the horn would interact. the tuning frequency is ok, but i note that between the tuning frequency and the f3 of the horn the responce is combined. it this going to sound funny? and also a really newb question just to finish, where should i put the port? iv been tkinking about going double on the lows as it just gives so much more spl and a much flatter responce, and i was thinking of porting between the two mouths. would that be ok?

thanks
dave

Edit: based in madrid