Possible summer project

[bose301s]

Well, I would love to build a set of bookshelf speakers just for fun. I think I have the tweeter picked out, looks interesting and Zaph really liked it. It is the SB-Acoustics SB29RDC-C000-4 Ring Dome tweeter. It is a new take on the ring radiator from SB. The woofer is up in the air but candidates are the 6" SB mid, the Mach 5 MLI-65, Peerless 6.5", Vifa 6.5", AE 6.5" and the Dayton RS-180. I am leaning to the AE or the SB, but if anyone else has some good suggestions I am all ears.

[Jed]

The SB drivers are excellent. You'll have to wait a bit for that tweeter though until it is in stock. I've designed a few speakers using the SB drivers and Vifa XT25 tweeters. Sounds great at the price.

[bose301s]

The SB drivers are excellent. You'll have to wait a bit for that tweeter though until it is in stock. I've designed a few speakers using the SB drivers and Vifa XT25 tweeters. Sounds great at the price.

I considered going that route as well, but it seems the SB tweeter probably has a better dispersion pattern and looks to have a larger radiating area. I think I will go with the SB woofer as well, but what I am in need of is crossover help. Was thinking of a 2nd order L-R around 2k-2.2k, but not sure on exactly what frequency to use or if I will need any filters. I should be able to get help from John Janowitz at AE Speakers this summer so that could help, but I would like to do the majority myself.

[Jed]

If you go 2nd order you'll need an electrical delay circuit if used on a flat baffle. Or, you could step the baffle or slope it about 10 degrees so that phase will align appropriately for a 2nd order transfer function. The SB 6" driver is pretty tough to hit a 2nd order acoustic slope. I managed it with the 5" but not the 6".

[bose301s]

Would a 3rd order work better then for the woofer? And since I am new to this I have to ask, how do you figure this stuff out ie. the phase differences and that stuff. I mean, you obviously are a talented designer so if you let me pick your brain I am definitely going to

[Jed]

how do you figure this stuff out ie. the phase differences and that stuff. I mean, you obviously are a talented designer so if you let me pick your brain I am definitely going to

I can figure out the phase requirements after taking the measurements --which includes the phase data. After shaping the response into a theoretically perfect 2nd order slope, there's not much one can do to delay the phase with a standard crossover if the acoustic centers are not radiating from the same plane and shallow slopes are desired. Therefore the phase alignment is generally taken care of either acoustically or electrically (ladder delay) given the options I spoke of above. I'm speaking from direct experience after working with the drivers. 3rd order might be okay... but honestly 4th order slopes with the 6" worked perfectly. 4th order slopes are much much less sensitive to driver acoustic center offset differences. You can also look at the FR of the 6" and get a pretty good idea how difficult it is to shape that ragged frequency response above 2k into a nice smooth shallow slope-- such as 2nd order.

[bose301s]

I can figure out the phase requirements after taking the measurements --which includes the phase data. After shaping the response into a theoretically perfect 2nd order slope, there's not much one can do to delay the phase with a standard crossover if the acoustic centers are not radiating from the same plane and shallow slopes are desired. Therefore the phase alignment is generally taken care of either acoustically or electrically (ladder delay) given the options I spoke of above. I'm speaking from direct experience after working with the drivers. 3rd order might be okay... but honestly 4th order slopes with the 6" worked perfectly. 4th order slopes are much much less sensitive to driver acoustic center offset differences. You can also look at the FR of the 6" and get a pretty good idea how difficult it is to shape that ragged frequency response above 2k into a nice smooth shallow slope-- such as 2nd order.

Ok, still over my head at this point, lol. I am definitely wanting to learn though.

[Jed]

Just let me know if I can answer any more questions. SB Acoustics recently posted on my forum to suggest I do a kit with the 4" and 8". I'll definitely be working with their drivers in the future given the excellent value. More than likely that will include the new tweeters as well. Just have to wait for them to get in stock at madisound.

[bose301s]

So, I think I am definitely going to do this design. I changed to wanting to use a 4th order @ ~2100Hz, maybe change that a little dedending on suggestions. Also, I want to do the 10 degree step passively, so if you could help me with that I would appreciate it.

[Jed]

Can you take measurements?

[bose301s]

I do not have anything to take measurements with, but I am up at school and the AES group probably does, I should be able to get in and use their equipment if need be.

[Jed]

I do not have anything to take measurements with, but I am up at school and the AES group probably does, I should be able to get in and use their equipment if need be.

If you can get me the files for the FR and Imp for the drivers just let me know and I'll work up a crossover for you.

Jed

[bose301s]

If you can get me the files for the FR and Imp for the drivers just let me know and I'll work up a crossover for you.

Jed

I appreciate it a lot man. I am definitely wanting to learn, but help with the first crossover is a plus I am probably going to buy the Loudspeaker Design Cookbook, unless there is something better out there.

[Jed]

I appreciate it a lot man. I am definitely wanting to learn, but help with the first crossover is a plus I am probably going to buy the Loudspeaker Design Cookbook, unless there is something better out there.

That's a good book and worth reading. It won't tell you how to design a crossover however. You're better off reviewing as many threads here for that info.

[bose301s]

You know what, Zaph has actually tested both of those drivers so if you could use his graphs and design it that would be awesome, otherwise I am sure I could do the testing.

[Jed]

You know what, Zaph has actually tested both of those drivers so if you could use his graphs and design it that would be awesome, otherwise I am sure I could do the testing.

You might hit up some folks at PE to run a simulated speaker design for you. I only use sims for modeling a concept, not finalizing a speaker. There's no substitute for good measurements in the intended box IMO. The speakers I've heard that were done with sims only, never fully sounded right to me. But that's just me.

[bose301s]

You might hit up some folks at PE to run a simulated speaker design for you. I only use sims for modeling a concept, not finalizing a speaker. There's no substitute for good measurements in the intended box IMO. The speakers I've heard that were done with sims only, never fully sounded right to me. But that's just me.

True, but I am still new to this, but you have already helped me a ton, I definitely want to thank you for that.

[bose301s]

If I were to change drivers it would be between the Exodus EX-6.5 Midwoofer and the CSS SDX7 Subduction 6.5" woofer. They are both extremely similar obviously, so out of those 2 which would be the better choice?

[bose301s]

Ok, I think I am going to eschew all of the choices I have posted up so far and go with the SEAS Prestige CA18RNX. I may have Madisound do the design for me, but if anyone has advice it is greatly appreciated.

[bose301s]

This project is looking less and less likely to happen due to financial circumstances. I thought I would have enough money for it, but some on foreseen events are making it look like it may not happen, however if it does, I will keep everyone posted, for sure.

[Jed]

Hey I'm sorry you won't be able to build your design. Hopefully when things turn around you'll be able to build a nice speaker. Take care,

Jed

[Jed]

Ok, I think I am going to eschew all of the choices I have posted up so far and go with the SEAS Prestige CA18RNX. I may have Madisound do the design for me, but if anyone has advice it is greatly appreciated.

There's a speaker I did for a guy here at htguide.com with that woofer and he liked it quite a bit. The schematic should be posted somewhere in the forum.

[bose301s]

Thanks Jed!!

It isn't 100% for sure one way or the other, it's really a 50/50 thing ATM, but that seems to be dropping still, lol. If it does happen I will do my best to post it up, I am working with John Janowitz from AE Speakers some and he will be able to help me a lot with my design and building it.