Could use some input on my Econowave derivative speaker plans

[JZatopa]

So over the past few years I have amassed a collection of drivers that have just been sitting around. I think it might be time to put some of them to use but I could use some input on the direction I am taking. The following are the drivers I currently have available.

SEOS 12 Waveguide
JBL 2370 horns
JBL 2425j
B&C DE500
JBL 2225H 15"
18 Sound 6nd430

So my current thinking is to KISS by making a ported box and putting the JBL 2225H and SEOS + DE500 in there. Is there anything I should be considering before I take this path.

Some things I'm considering.

- Buying a pair of the SEOS 15", as it would be a small investment. However I'm not sure it's going to make that much of a difference from the 12".

- Using the JBL 2425J instead of the DE500. I'm not sure how these two really stack up to each other.

- replacing the 2225H with a more contemporary driver

- instead of a ported box I go with a TL

- The final thing I am thinking about is buying a 12" driver and making the system into a 3 way with the 15" picking up the bottom end.

Thoughts?

 

[gedlee]

The DE500 is a very good driver, I use it almost exclusively. But I also prefer the B&C woofers, especially the 15NDX100. These two drivers are a great combination, although in some cases one has to actually pad down the 15" woofer when using a DE500 and a waveguide. The 12NDX100 does not require this pad, but the 15" system will result in a slightly higher DI that the 12" one. If you want to use the 15" and not pad it then use the DE250 which has a few dB more output at 10 kHz than the DE500. To me multiple subs are a requirement and in that situation close box is better and simpler.

 

[LineSource]

You can build a basic box ~7cuft for the JBL 2225H with a double thick baffle which allows different horn baffle sections to be screwed in for easy switch over. There are a few successful diy designs where the SEOS-15 is crossed to a 15" woofer at ~1000Hz using BW3/BW3 circuits or LR4/LR4 circuits. Designs with the more expensive SEOS-18 with a 1" CD are also on the web. SEOS-12 is not wide enough.

In the future you can purchase a 1.4" compression driver like the Faital HF146 and explore the more traditional 800Hz crossover 2-way.

The SEOS-24 with a 1.4" coaxial compression driver like the BMS 4594Nd with a 500Hz crossover would also fit this cabinet for a controlled directivity 3-way with retail cost of $750/speaker. The SEOS24 = 24.4" wide, so if this is a long range dream, a 26" wide cabinet avoids overhang.

 

[JZatopa]

Thanks for the input Earl and Linesource, I appreciate it.

After reading this thread, I think I am going to follow the basic recipe. It looks to me like I could use the core of the crossover here and just modify it for use with the impedance of my drivers.

Here is the current plan as it sits.

- 12" seos and DE500 (from the AVS link it sounds like the 15" would add very little)

- stick with 2225 drivers, I have them so might as well use them. I may not get the lowest extension but I will be able to match these speakers with any amp I want

- I am still not sure about what type of box to put these in. Using WinISD it looks like ported is the way to go unless I want really bass shy speakers. However I do not know how to use the transmission line feature in WinISD. My gut is telling me that building this as a TL might be the way to go to really get the bass extension I'm looking for. Is there another way I could model a TL for this driver or could someone give me a bit of guidance here?

 

[gedlee]

Again, I still prefer closed box and EQ. Even a bass control on a receiver to boost the low end of a closed box works well. But the real problem will be the crossover as this can be very tricky for a piston source crossed to a waveguide. That's because the waveguide is never flat and you have to tailor the response as well as the crossover to match the woofer, which is never easy to do. Its not too hard if you go active, but can be a real PITA if done passive.

 

[AllenB]

- instead of a ported box I go with a TL

When I first started down this road I went with a ported box with a 15" driver. This was unusual because I've mostly been making closed boxes since deciding I preferred them. I then found that I had more difficulty incorporating the ported box with multiple subs and still preferred the result of a closed box. Dr Geddes explained that extension of the mains' response is not the be all and end all when using multiple subs, and this works out well. I have also found that transmission lines (excluding extreme versions) seem the same to me as closed boxes.

 

[JZatopa]

Again, I still prefer closed box and EQ. Even a bass control on a receiver to boost the low end of a closed box works well. But the real problem will be the crossover as this can be very tricky for a piston source crossed to a waveguide. That's because the waveguide is never flat and you have to tailor the response as well as the crossover to match the woofer, which is never easy to do. Its not too hard if you go active, but can be a real PITA if done passive.

I completely agree with you on the active crossovers and EQ, I've been running them in cars for over 10 years. It's funny how that just got to home audio and it's been in car audio since the 80s. However I am not at a point where I am ready to take things to that level with my system. I'm looking to have a set of speakers that I can drive with any amplifier I have and if I feel they need bottom end I can always use a sub.

If I am going to go down this road I think I am going to try a TL enclosure. I did think about going sealed and adding a dipole subwoofers as speaker stands but I really just want to use the equipment I have laying around as much as possible.

I've attached two models I've come up with. Option one is slightly tweaked by me and option 2 is just what the wizzard puts out with a little stuffing. I am new to TLs and I am not used to seeing such an uneven curve for my models. Does the first option look about right?

I didn't play with the driver positioning, if this needs to be moved, what should I be looking for in the response? It's not very clear on how this should be set.

 

[planet10]

I don’t like the little peak up at the bottom… perhaps tune them a bit higher?

dave

 

[JZatopa]

I don’t like the little peak up at the bottom… perhaps tune them a bit higher?

dave

Hi Dave, thanks for the help, I'm new to modeling TLs. When I change the tuning it seams that all I do is move that hump, nothing seams to eliminate it. Is there a trick I am missing here? I've been modeling this is as straight TL, would a taper be a better option?

 

[planet10]

I don’t do TL modeling — i pas sthat off to Scott (woden) as i don’t like using Windows. I do know that that kind of bump is something i avoid when designing any loudspeaker.

I’d guess you might have to shorten the line (and maybe make it fatter) to get the LF roll-off smoother.

Id the terminus of your straight TL the whole cross-section? If so you might want to add a resitricted terminus and make it an ML-TL.

dave

 

[charlie2]

So over the past few years I have amassed a collection of drivers that have just been sitting around. I think it might be time to put some of them to use but I could use some input on the direction I am taking. The following are the drivers I currently have available.

SEOS 12 Waveguide
JBL 2370 horns
JBL 2425j
B&C DE500
JBL 2225H 15"
18 Sound 6nd430

So my current thinking is to KISS by making a ported box and putting the JBL 2225H and SEOS + DE500 in there. Is there anything I should be considering before I take this path.

Some things I'm considering.

- Buying a pair of the SEOS 15", as it would be a small investment. However I'm not sure it's going to make that much of a difference from the 12".

- Using the JBL 2425J instead of the DE500. I'm not sure how these two really stack up to each other.

- replacing the 2225H with a more contemporary driver

- instead of a ported box I go with a TL

- The final thing I am thinking about is buying a 12" driver and making the system into a 3 way with the 15" picking up the bottom end.

Thoughts?

Best to experiment with exising components.

here is my take

use the jbl 2225 in a ported box according to jbl spec (online) rough box nothing fancy 40hz tuned

use a scrap peice of wood/baffle to mount the jbl waveguide and the seos directly above for 1200hz

use jbl 2425 800hz to 1200hz and b&c on seos 1200hz up

measure from centre of bass driver no less than 17" from woofer to center mid(jbl)

invest in dsp and microphone and tailor to suit

a pic of mine mixed but sounded great

 

[gedlee]

I do know that that kind of bump is something i avoid when designing any loudspeaker.

dave

Given that the "bump" is well into the frequency range where the room dominates the response, does it really matter?

 

[planet10]

Yes.

dave

 

[JZatopa]

With this being the first TL I've tried to model, I am out of ideas here.

Is the JBL2225 just not suited for TL use or am I doing something wrong in my model?