Still need assistance designing a midbass cab

[rcw666]

Ten decibels is about twice as loud.

The delta 12 probably has about at least 4db. power compression at 250 Watts.

What you find is that you can end up with too much on axis midrange if you try to compensate for low power response in this region by equalisation, this is why commercial designs use a phase plugged horn and a driver with rising response.

If you use a constant directivity device with a delta 12 you will have to use 6db. octave equalisation to maintain on axis output.
rcw

[Xoc1]

Klampykixx
There are many things to concider - not the least being the cost of whatever you decide to build.
You have the Delta 12a drivers, adding an other pair would take you a lot closer to the sound pressure levels you want.
I like the Eminence Delta for a mid range driver It has a small xmax but is efficient. The Delta gets a bit rough above 1.7Khz.
A horn loaded cabinet has greater efficiency than a reflex, but it is over a smaller bandwith.
You will struggle to get the mid horn to go low enough to match a tapped horn sub, and you will need an exceptional & expensive compression driver to get low enough to meet the upper bandwidth of the mid horn.
Using a reflex cabinet reduces the cost of the compression driver as the mid can be used to a higher frequency.
The cost of the compression driver and its horn will still be a very conciderable part of the cost of the speaker.
Roberts suggestion to use the reflex tuning and a filter to keep the cone excursion low where the mid crosses over to the SS15 cabs is very interesting. Dont forget that the Delta 12a has a fairly low xmax at 2.4mm and your current cab is probably exceeding that figure and distorting.
In fact using this idea could be the answer to getting a mid cabinet to run to a low enough frequency to meet a tapped horn sub for a lot of users.
The Behringer CX2310 is an improvement on what you are running at the moment, but ultimately is probably not flexible enough to acheive everything that you will want to do the long run. A digital crossover unit such as the DCX2496 would allow you to tune your system into something really exceptional.

[klampykixx]

i have been told by someone in the trade, who knows my system to make sure i get a DSP. so that will be attended to in the future.

what im trying to do is achieve a cab that uses less power to get loud. so, if i can make it 2x as loud as it is, with the same power as i do now, then in MY opinion, thats winning.

i will eventually get another pair of drivers, and when i do, i feel that Direct radiators, just wont cut it. regardless of how many i get.

[rcw666]

in the end Klampy your system just does not have enough acoustic power output for the venues that you are using it in, and by far the best way to fix it is another pair of pole boxes with QB5 II alignments on all of them, and at least bi amping.

A horn loaded system that you envisage needs to be four way, you can make a three way one but you need a two inch throat compression driver and they are big bucks.
Look at the p.a. article at the ESP site, Rod has been in the business for over fourty years and knows it backwards.

The point about power compression is that if you spread the 250 Watts over two drivers then each one has around 2db. power compression, and up to a frequency that is about equal to the distance between driver centers the coupling between them gives a 6db. boost, the lower power compression also gives 3-4db. so you are getting on for ten just by using the same power and a second set of speakers.
rcw

[klampykixx]

Originally Posted by rcw666

in the end Klampy your system just does not have enough acoustic power output for the venues that you are using it in, and by far the best way to fix it is another pair of pole boxes with QB5 II alignments on all of them, and at least bi amping.

ive tried blocking the port on my cabs just to see if it makes any difference, and as far as i could tell with my ears (my tuning tools) it sounded no different, and definately no louder. so based on Bassbox pro, and also Hornresp. theyre as loud as theyre going to get, as they are. and i did simulate different sized sealed cabs and specifically picked the best compromise between quality and SPL, with top duties in mind.

i am well aware that they are not loud enough (or enough acoustic power) to fill this venue. BUT, last night i had a "proper" rig to run and it had the EXACT same issue that i was with my rig. it had 2x12 active tops and 2x15 active reflex subs, and in that hall, it seems nothing carries, it just echoes. resonates horribly. so just going to accept that fact for now, and deal with it when it actually becomes a problem.

Originally Posted by rcw666

A horn loaded system that you envisage needs to be four way, you can make a three way one but you need a two inch throat compression driver and they are big bucks.

and that is ok. right now, obviously i cant afford it, but longer term, that is a bridge i will have to cross. and im well aware of that.

more drivers are definately on the cards, just not straight away.

even to the point, that im highly considering HD215 cabs on each side under the deltas using the d12 as a dedicated mid, not midbass. and then, it will most likely need to be in a horn. so the same principle applies IMO.

Originally Posted by rcw666

Look at the p.a. article at the ESP site, Rod has been in the business for over fourty years and knows it backwards.

i did have a look. and it comes back to the point where i did assess my cabs in sealed form, and i have checked numerous sealed volumes on HR with minimal increases/ decreases in output. and In My Personal Opinion, of MY gear, i found my current setup to have the overall best output for what it is.

Originally Posted by rcw666

The point about power compression is that if you spread the 250 Watts over two drivers then each one has around 2db. power compression, and up to a frequency that is about equal to the distance between driver centers the coupling between them gives a 6db. boost, the lower power compression also gives 3-4db. so you are getting on for ten just by using the same power and a second set of speakers.
rcw

my amp driving the cabs is 2x600rms. i have plenty of headroom power wise. spreading 250w over two cabs, isnt the issue, as if i ran two drivers per side, it would be in parallel anyway, which (according to its spec) brings power up to that

2 x 600 Watts into 4 Ohms; 2 x 320 Watts into 8 Ohms

so i wouldnt infact be spreading 250w between two, they would be getting 300w each.

Originally Posted by rcw666

and at least bi amping.

bi-amp i presume means to amp the woofer and the compression driver?? this is also something that will come further down the line. just again, well and truly, not in my budget Yet.

this is my amp rack.



and how it was setup when i did the test.



sub amp was just flickering the limiter but i feel they could have taken more power as they werent even getting warm at that level.

[klampykixx]

just some things i want to add to this convo.

by no means is my rig quiet, or soft, or lacking. really.

for 2x12 top cabs, i am VERY VERY happy with the way it sounds. i am Proud of my system. i built the whole thing. its my baby. and i love it!

second thing, im not saying you guys are wrong, at all, with the QB5 stuff. without building a new cab just to test, i cant get my head around it being "that much" louder because it is slightly smaller internal volume.

however, i CAN understand that a horn speaker is just like cupping your hands around your mouth when you talk. it doesnt make your voice louder, but it focuses it, and makes it SEEM louder from the other side. this is indisputable.

right this minute, i feel like my tops are like a bare light globe. just glowing in the open. put a shade/reflector on it, and it glows MUCH brighter in the focused area.

im happy to admit that i have pretty limited but basic understanding of my system as far as technical details are concerned. however, producing dance music for the past 10 years, i know what i want it to do, and have a very basic understanding of how to get it to do it.

i was reading a "horn vs reflex" thread on here, and the horn won every time in outright SPL for a given input power.

[col]

If I get time I will do some live testing in the yard next week and will post some comparisons.

Setting the filter won't be a problem MiniDSP is great for this kind of thing.

Originally Posted by rcw666

These are winsid simulations of a 30 litre box tuned to 100Hz...

For an input of 250 Watts the cone excursion is as shown, and the spl over this range is 120db.

The input filter has a q=.5, this is a second order L-R, it can also be done with two capacitors somewhere in the signal chain.
rcw

Edit: comparisons between QB5 II and a 50L "optimum" BR.

[klampykixx]

Originally Posted by col

Edit: comparisons between QB5 II and a 50L "optimum" BR.

i would be very appreciative of the results also

[rcw666]

The only thing I can say is that I can post AES journal papers about everything I have said, and they have been written by some of the best in the business, if you don't want to hear what they say that is up to you.

Putting that amount of power into a delta 12 in a sealed box causes quite severe power compression, getting on for 6db. I can refer a paper that shows this, not to mention an excursion that far exceeds its linear one, this in another paper.

Good luck with it.
rcw

[klampykixx]

by all means, im not saying they will handle that much power, just saying its there and is available.

ill be doing some more testing and adjusting in the near future thanks to a fellow forum member i met just now.