Tuning reflex high?

Hello all,
Can anyone tell me if there is any downside to tuning a 15" driver used for mid (100Hz-800Hz) to a highish frequency like 80Hz? I am building some new mid/hi cabs and most midbass 15's seem to dip a little from 100-200Hz ish when tuned around 50-60Hz as they want to be.. However, tuning higher gives me more output around 100Hz where they would come in. The other alternative is tune lower and use EQ to correct the dip.. Which would be the best solution for a cab that will always be used with a sub and never full range?

It sounds like you're siming this. You are approaching a frequency that doesn't gain anything by tuning. Tuning is used to get the best response in the bass out of a cab,but the word is bass. When it comes to mid frequencies out of a cone you could be easily getting reflections in the cab that will come back onto the cone and cause a null. A small mid chamber eliminates this because a small chamber will be smaller than some of the longer wave lengths coming form the speaker. If you are talking about mid for vocals, it would be better served with a 12. What sort of 15 do you have for mid. At best it will only be a general bass speaker or a dedicated Bass/Mid speaker.

Hi Tony,
Yes, I am simming in Bassbox Pro..At the moment I am looking at B&C 15NW76. I thought a 15" would be a better choice as it has to reach around 100Hz to meet the subs and upper crossover can be low (600Hz if necessary) as I will be using a coax 2" on large(ish) horn above it. All the 12" drivers I have modelled have had even more of a dip between 100-200Hz.

I know you may be stuck with your configuration, so I assume you will have a 2 way cab plus sub, it's just that I see so many people using a bass speaker for mid, and in principle its the wrong speaker, however, I also do this with a full range cab typically 15 plus 1" or 2" horn. Most floor monitors have this configuration. The 15 that you have is ok for this, and a Neo is usually more prominent in the mid range than a normal speaker. you should be able to get this fairly flat to join the CD. Is it active or passive?

It will effectively be a 3 way cab with the coax 2" I suppose... Crossover between the 15" and the horn will be active and a passive between the two sections of the comp. It's only really the need to get down to 100Hz ish that makes me think 15" and 15NW76 I already have in some other cabs so it's easy to experiment with!
I see that you use DCX50 in the R2U system, how do you find this driver crossed over around 600Hz? Shame they don't do a passive network for it like BMS do for their coax comps.

I have a 10K hi pass filter that I make for these compression drivers to divide the two halves. It's just a row of caps. no coil needed.

Wow, that's pretty easy! Just a 1st order hi pass then?

Yes, and the reason for that is that at 10k, the small diaphragm at the front is well protected, so there's no need to give it any type of steep slope with those nasty coils.

Thanks Tony, usefull and interesting information as always! :thumbup: