3 Way Design - First Timer

[rpb]

I was planning on using the drivers I chose because they are on sale, well spec'd, and people have used them to some degree of success. If anything, I've"qualified" them. Not necessarily chosen them.

The 830869 is an 8" woofer. I am not going to use a 12. I can buy almost 3 of the 8's for the price of the 12. Since I want to go narrower than usual the 8 is the logical choice. Using 4 per side should compensate for anything that is seen as a shortcoming.

As for the 830991... It's quite smooth through the midrange and am planning on using it sealed. And it's on sale. I had considered the SB Acoustics PFC drivers as well due to their price.

From an efficiency standpoint, four 8s would be too efficient for my mid and tweet. I just like the sensitivity and surface area of a quad vs dual 8s. Actively crossed it's a non-issue but would be a problem going full passive I suppose. The Neo 3 I have is a PDR. They're only 90.5db efficient come to think of it. I will look into the other Peerless driver mentioned above.

It's frustrating what is and isn't available here. Free shipping and living stateside would make this a much more affordable hobby heh.

Sorry for my confusion. I clicked on the 830669 rather than the 830869. I forgot that you were going active between the mid, and woofer. That makes everything a lot easier.

[mortron]

Yeah I have to admit that the idea of going quad is firmly rooted in active realm. Once I got the MTM playing nice and decide to employ a passive WM crossover I would have to go to two drivers per side.

I could likely find use for the other 8's if need be ;)

[Wolf]

mortron, You're using efficiency and sensitivity interchangeably, and they are not the same thing. Efficiency is based on power at 1W, normally specified as a percentage. Sensitivity is based on a voltage of 2.83V, and normally specified as a decibel output level. Since drivers are voltage sensitive devices, and not power based, and everything can be based upon the 2.83V specification regardless of impedance rating, then sensitivity is what you should be using for output and simulations. The Neo3PDR has a sensitivity of 90.5dB. This is not it's efficiency.

Best regards,
Wolf

[mortron]

My bad Wolf... And the worst thing is that I know bettwr than to confuse them!

Apologies.

I am glad I started this thread, it has really helped with my research and where I need to shore up and what I may find a challenge as things progress.

But yes... Neo 3PDR is 90.5db... so that may change things. For some reason I rhoughtit the other model with higher efficiency. These came from Danny at GR Research about 3-4 yrs ago.

[rpb]

The mtm sensitiviy will be determined by the mid-ranges. So, after BSC, the sensitivity will be about 86dB. The tweeter will need to be padded to match. The level between mid-ranges, and woofers, is matched with the active x-over gain adjustments.

Maybe I missed something else. Why are you concerned about the Neo3 sensitivity?

[mortron]

Was just concerned the mids would have too much output for the 90.5db tweeter.

[Dave Bullet]

Was just concerned the mids would have too much output for the 90.5db tweeter.

I find the secret is starting with a reasonable BSC level and making sure you use the right sensitivity target of the woofer to work out overall system sensitvity.

You may be able to play the tweeter without padding. It probably limits how low you can XO as you'll lose acoustic output.

It depends on the target slope you are planning (or flat response). I did an excursion modeling spreadsheet that takes 3 drivers so you can work out which one will "xmax first". Can't find it now

[rpb]

Was just concerned the mids would have too much output for the 90.5db tweeter.

The factory spec and graph for the Neo3PDR says it's 93dB sensitivity. The dipole is 90.5dB. I think 90dB would be sufficient anyway.

Is this the correct data?

https://www.parts-express.com/pedocs...ions-44576.pdf

[mortron]

Mine is dipole. That said, I'm going to make a stuffed chamber behind it isolated from mid. So I guess it will go back up?

[rpb]

Have you used software to simulate the baffle step?

[xmax]

I have always been extremely happy with many SB acoustics products, peerless is also good.
For subs I would look very closely at the dayton RSS HF line. They perform about 90% as
good as anything out there in my opinion.

[rpb]

Was just concerned the mids would have too much output for the 90.5db tweeter.

I just ran a sim on a 10 x 60 baffle, and you might indeed have an issue. Here's the sim. You could run the mids in series.

[mortron]

I hate this tweeter... Aspects of it I love, others I hate. They were a gift though, so I have em.

Maybe I just say to hell with it and make a TMW.

Or I pull up my pants and find a different tweeter.

I have been quite busy and haven't had a chance to run any sims yet. I'd like to find a used windows PC so I can run progtamsa bit easier. Wine doesn't seem to do much for me, may have to try again. Mac's are great until you need a PC only program.

[PWR RYD]

I do not think you will have a sensitivity issue using your Neo3PDR with a pair of 830-991 woofers in parallel. I just completed the crossover design and voicing of my project using a XT25TG and a pair of 830-991's. On a 6.75" wide baffle I still had to pad down the XT25TG over 3dB. Looking at the manufacturer's plots for the two tweeters it looks like the Neo3PDR is more sensitive. Grant it I am running my 830-991'a as mid-woofers so I have a full 6 dB of baffle step loss, whereas you will be crossing them over higher and have less baffle step loss to compensate for. Still I think there is plenty of sensitivity to spare. Here are the two manufacturers' plots:

[rpb]

I hate this tweeter... Aspects of it I love, others I hate. They were a gift though, so I have em.

Maybe I just say to hell with it and make a TMW.

Or I pull up my pants and find a different tweeter.

I have been quite busy and haven't had a chance to run any sims yet. I'd like to find a used windows PC so I can run progtamsa bit easier. Wine doesn't seem to do much for me, may have to try again. Mac's are great until you need a PC only program.

Tell me about the active x-over you have. Can you do different slopes, and x-over points for woofer and mid.

Also, how close to the wall do you plan to put the speakers, and how forward, or laid back, do you like your music?

The baffle response I posted made me think that it might be hard to shave off 5 or 6dB. If you add a passive high-pass filter, and possibly some padding, I'm sure it will work.

How soon could you make a test setup for the tweeter, and measure it?