Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

[Deward Hastings]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

You can boost with an amp, or you can cut with a crossover . . .

With your scheme you have to do both . . . what's the point? If a separate amp is going to be required (as it is with your "passive" example), why bother with the passive stuff (which only degrades performance) at all? It's an incredible waste to avoid just doing it right in the first place and handle the response correction at line level.

[Jim Griffin]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

B-G Radia already has a similar design--the FS-420. A dipole with two Neo 10 and a Neo 3 with two 6.5" woofers in a sealed box at the base. All in a slim floor standing speaker. The crossover points at 250 Hz and 1.5 kHz.

http://www.bgcorp.com/PDFs/FS-420%20Radia%20Product%20sheet%20.pdf

[Pete Schumacher]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

With your scheme you have to do both . . . what's the point? If a separate amp is going to be required (as it is with your "passive" example), why bother with the passive stuff (which only degrades performance) at all? It's an incredible waste to avoid just doing it right in the first place and handle the response correction at line level.

What??????

Separate amp? No one is talking about a separate amp, but you. I'm showing how you can do it with a single amp, passively. What is so hard for you to understand?

You proved your point but it's expensive trying to force a low q driver to do something it doesn't want to do.

You can get better sensitivity (less amp needed) with cheaper (high q) drivers, which in turn will lead to a less expensive crossover.

But look at the title of the thread . . . or did the fact that dual RS225 was the intended woofer of choice somehow escape your notice?

[diy speaker guy]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

But look at the title of the thread . . . or did the fact that dual RS225 was the intended woofer of choice somehow escape your notice?

Of course not Pete. Did you miss this part?

Unfortunately, I don't have a clue about how to do an OB.

I'm letting the guy know that there are much cheaper and easier drivers to work with.

[dst]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

check out this baby. how about a version with two PE woofers as you suggest:

http://www.audax-speaker.de/index.php?module=shop_articles&index%5Bshop_articles%5D%5Baction%5D=details&index%5Bshop_articles%5D%5Bdata%5D%5Bshop_articles_id%5D=83&lang=en

[Deward Hastings]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

What??????

Separate amp? No one is talking about a separate amp, but you.

Did you miss the part (in the OP) about miniDSP?

I'm showing how you can do it with a single amp, passively. What is so hard for you to understand?

It would be foolish to design/build a 75dB "sensitive" speaker . . . and I'm pretty sure the OP isn't foolish, or asking for such a foolish dipole "solution".

[Pete Schumacher]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Did you miss the part (in the OP) about miniDSP?

It would be foolish to design/build a 75dB "sensitive" speaker . . . and I'm pretty sure the OP isn't foolish, or asking for such a foolish dipole "solution".

The fact of the matter is that even with a separate amp, the limit on system SPL is the woofers. The other fact, is that even with an amp, the speakers are still, 75dB/W, with active changing nothing, except adding cost.

And because this setup would be so limited by the woofer output, 75dB is not an issue, especially in a smaller room. Using Dual RS225 on a narrow baffle is just fine in a passive implementation.

Foolish? Using Dual RS225 with a separate amp as though it will produce more bass, yeah, pretty foolish.

[MSaturn]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

personally I think you guys are arguing the wrong thing (though I agree, I've got some 12" JAMO drivers that tell me big cheap drivers are the way to go with dipoles); why use the neo8 only to 800Hz? have it come in wherever baffle step ends. probably 450 or so. it can handle that easily.

[Pete Schumacher]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

personally I think you guys are arguing the wrong thing (though I agree, I've got some 12" JAMO drivers that tell me big cheap drivers are the way to go with dipoles); why use the neo8 only to 800Hz? have it come in wherever baffle step ends. probably 450 or so. it can handle that easily.

For bass, bigger is always better!!!

[6thplanet]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Well they ended up back in standard H-frame format. They still produce amazingly clean bass and lost the midbass peakyness. I tweeked the crossover into a nicley voiced area to follow up with builing a second unit. So I put some dust in the air this weekend and knocked the other one out.

Yes STEREO!! Man, it just keeps getting better...if you've never messed with this type of set-up you have to try it! The bass is so accurate, like a sealed enclosure but with out all the need of being perfectly sealed and none of the reflection/resonate/pressurizing crap going on inside a normal box. It just plays and sounds so unstressed and natural. Literally these things are just screwed together, no glue, no sealant, no polyfill/FG/wool/ect., no BS! It's cool as h e l l , pick a driver with a Qts above .5 , an Fs around the 30's/40's, and some decient Xmax. I got super lucky with these 8" deals from the tent sale that they load in an H-frame this nicley. A cheep unit we're using in a freinds speakers is this: MCM Electronics Part #: 55-1300 It loads really good in an H-frame, cheep enough to get your feet wet if you'd like to try it. Anyways...

BG's definatly will go to 500Hz (12dB), H frame at 200 Hz(12dB), figure in the midbass gain from the top end of said H frame and they blend rather well.

The woopdee-doo @ 200Hz is room junk of course, but all in all not to bad, ehh?
If you do go active between your RS's and the neo's you'll be plenty happy!! Doing it passively can be done as well...the Qts is a little low on the 8ohm units for passive H-frame, the 4's are a bit better, but then you have to have an amp that'll work under a 2 ohm load, or put out some killer watts at 8ohm.

[diy speaker guy]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

The woopdee-doo @ 200Hz is room junk of course...

Actually that big spike looks a lot like an H frame resonance. Did you simulate this? You can't run an H frame up very high unless you want to notch the H frame resonance - or just live with it.

EDIT - actually, the smaller bump at 300 hz is probably the H frame resonance, it's hard to tell how deep they are.

[diy speaker guy]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Here's a simulation of dual GRS 6.5 inch drivers on an 8 inch wide baffle.

First graph shows response at 1 watt (note the sensitivity).
Second graph shows response at xmax (3mm x .707 = 2.1 mm).
Third graph shows excursion 20 watts (xmax).



The 4 GRS drivers cost about $28, approximately 1/2 the cost of a single RS225. If it's not loud enough as shown, the woofers can be doubled up (4 per side) for an extra $28.

This design is shown without any filter. Very easy to work with with inexpensive passive components, much smaller than the ones required to beat the RS225 into shape. It doesn't seem to need a high pass either, although if one were added at 100 hz you could get a bit more spl than shown.

The sensitivity and low power handling mean you can use any amp you like, even a low power chip amp.

Cheaper drivers, cheaper crossover requirements, smaller baffle. Why fight with a driver that doesn't want to do what you want it to?

If response below 100 hz is desired I'd probably pick a different driver, I just used this one to compare to Pete's simulation.

(And I agree there's really no need for a mini dsp here.)

[marvin]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

I experimented with this very combination of drivers with a passive crossover. Never personally liked the NEO8 running open baffle (at least as a single). The rear chamber sounded better to me. Doesn't mean it can't be done, but I didn't think it was worth it.

I know somebody did an MTM style Neo8/Neo3/Neo8 and was pretty happy with it. I'm not sure if there's enough in 800-1500hz range to make it work effectively with just one.

My experiments are detailed here: http://www.lonesaguaro.com/speakers/Neo83/Neo8Neo3.html

Maybe it'll save you some time/effort.

Isn't the Neo8 the driver Dennis Murphy used OB for his Philharmonic series? I've read only good reviews of them....

[Deward Hastings]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

If it's not loud enough as shown, the woofers can be doubled up (4 per side) for an extra $28.

How would you do that on a 8" baffle? And what does it do to the vertical polar if you make some sort of truncated line aray out of them? Are you really suggesting that we throw away all our Scan and Seas drivers and use this $14 wonder? Is it that good ? ? ? Perfect for under a RAAL ? ? ? :rolleyes:

What do those drivers sound like (through the lower midrange) while you're driving them to their excursion limit on the low end? No increase in distortion or muddiness?

There's nothing (well, only a few things) wrong with the idea (considered by itself), but in implementation it may not work out so well . . . (I gather that you haven't actually tried it, and we're just talking simulations here).

[diy speaker guy]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

How would you do that on a 8" baffle? And what does it do to the vertical polar if you make some sort of truncated line aray out of them? Are you really suggesting that we throw away all our Scan and Seas drivers and use this $14 wonder? Is it that good ? ? ? Perfect for under a RAAL ? ? ? :rolleyes:

Easy, Deward, I'm simply suggesting that there are easy ways to do things and hard ways. Why pay big money for a big magnet and then pay more big money to basically defeat that big magnet with big crossover components? It makes no sense unless you are going active crossover with dsp.

I have no experience with those particular drivers but there's absolutely no reason they shouldn't work just fine. If you don't like cheap drivers, just substitute for your choice of expensive high q driver.

With a low crossover point, a truncated array isn't going to be much of a problem, in fact at only 30 inches tall it won't act as much of an array at all at the frequencies it will be playing, and if you don't like it you can substitute the 4 six inch woofers with a single larger woofer.

What do those drivers sound like (through the lower midrange) while you're driving them to their excursion limit on the low end? No increase in distortion or muddiness?

How is that different than any other driver? If you push a driver hard distortion will increase, there's no driver immune to that. Assuming they are fairly rated, they will sound about the same as an expensive driver with the same cone area and xmax rating at the same spl. Considering the fact that these are being used as bass drivers in a 3 way they don't need to be special and certianly don't need to carry a RAAL sized pricetag.

There's nothing (well, only a few things) wrong with the idea (considered by itself), but in implementation it may not work out so well . . . (I gather that you haven't actually tried it, and we're just talking simulations here).

I'm not suggesting this is perfect (but it's also nowhere near as bad as you are suggesting). It's flexible, you can use different drivers or a single larger driver (is the Alpha 15 more to your liking?) I picked this driver for this excercise particularly because it is inexpensive and covers the same bandwidth Pete was showing but at about 1/10 of the cost and a response that is much much easier to work with, leading to a less expensive crossover and needing a much smaller amp, and all on an 8 inch wide baffle.