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Re: Definimax 4012HO - End of Life [message #91062 is a reply to message #91048] Fri, 11 October 2019 11:42 Go to previous messageGo to next message
Mabob is currently offline  Mabob
Messages: 11
Registered: December 2017
Location: Finland
Chancellor
Thank you Wayne and @Symphonimind!

I've read through the links you added Wayne and it gave me a better understanding of the importance of flanking subs for three π or four π speakers.

I've built one BR sub with a Dayton DCS255-4 10" I needed it to be small and these allow for a pretty small box about 40L box tuned to roughly 30hz. I will hijack and run the signal from speaker binding posts. I'm a bit skeptic about SPL output compared to the 3 Pi, but well see if they can keep up. Cutoff frequency at 150hz maybe? 'm not sure how steep the filter is on the plate amp. Second sub will be built soon and added.

I had a look at the T&S parameters for both 12LFA and Pro 12. I noticed that the LFA can handle more power 500W vs 400W for the Pro. But does this really matter? The Pro is more efficient 99 vs 94db and the lower MMS, does that mean less cone weight to move? What does BL stand for? Many noob questions, and sorry for hijacking the thread, this should probably be moved elsewhere.

The plan at the moment is to add a second flanking sub, upgrade to Delta Pro and move on to 6Pi from there. More work than going straight to 6Pi, but also way more fun and opportunity to learn.
Re: Definimax 4012HO - End of Life [message #91063 is a reply to message #91062] Fri, 11 October 2019 13:16 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17580
Registered: January 2001
Illuminati (33rd Degree)

Check out this document from Eminence's website:
It shows what each of the electro-mechanical parameters describe.

As for flanking sub setup, generally, we want 100Hz, second-order. I've found some combinations that aren't exactly that, but this transfer function seems to work best. The relatively gentle slope from a second-order filter leaves a lot of energy in the 100Hz to 200Hz octave, and it rolls off smoothly, roughly conjugating baffle step.

What we're trying to do is to blend each main speaker with the sub that's flanking it through the upper modal region, generally from about 60Hz to 150Hz or so. Blending lower is fine, actually desirable, but below 60Hz we get more benefit from distant distributed multisubs. The content below 60Hz from flanking subs is useful for extension, but doesn't help much with modal smoothing. Again, modal smoothing below 60Hz is achieved by distributed multisubs.

Baffle step occurs in the same 100Hz to 200Hz region for speakers this size so we want energy to fill-in the region below baffle step both for overall on-axis amplitude response and also for SBIR and modal smoothing.

Above 150Hz, we start to become localizable. That's not a hard-fixed number; I actually like to see the energy trickle off slowly between 150Hz and 200Hz somewhere. But we just can't run the flanking subs too high. I've found that 100Hz second-order is the "Goldilocks filter" for flanking subs.

I've actually found some amps with built-in bass and treble controls that can be adjusted for a pretty good flanking sub curve. You just turn the treble all the way down and turn the bass all the way up, and the resulting transfer function works nicely for flanking subs. It's a happy accident, I suppose. Level-set the amplitude of the subs to match the mains and you're done.

One example is the Audiosource AMP100VS. It's just a 50 watt amp, but that works well for people that have 10 watt SET amps for their mains. There are probably many other products of this type. If an amplifier has built-in tone controls that use second-order filters, and if the bass adjustment frequency is 100Hz or so, then the amp will work very well for flanking subs.

I've attached the spec sheet for this little amp. See the link below. You'll notice it lists the bass control as being a second-order 100Hz filter. That's what we want. Nice that the bass and treble controls are on the back too, 'cause that way it's out of sight. They're just set to make it a flanking sub amp.

Look for amplifiers like that.

When searching for amplifiers for your flanking subs, you can always try out a product and send it back if it doesn't blend well. Just open the box carefully and keep all the packing material so you can repackage it properly if it doesn't serve your purpose.


  • Attachment: AMP100VS.pdf
    (Size: 544.68KB, Downloaded 19 times)
Re: Definimax 4012HO - End of Life [message #91071 is a reply to message #90415] Sun, 13 October 2019 10:16 Go to previous messageGo to next message
paulp1960 is currently offline  paulp1960
Messages: 2
Registered: October 2019
Esquire
Hi Wayne,

I'm itching to build the 3 Pi speakers. How do you rate the B&C PLB100 compared to the other offerings including the Definimax 4012HO ? I assume you have done listening tests?

Also can I have the 3 Pi plans please?

One more question, I don't think I will use an amp greater than 200 watts per channel. Do the upgraded xover inductors help with power handling?

Thanks in advance

Paul.
Re: Definimax 4012HO - End of Life [message #91084 is a reply to message #91071] Mon, 14 October 2019 11:08 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17580
Registered: January 2001
Illuminati (33rd Degree)

You've got mail!

The standard crossover will work just fine with 200 watts. It doesn't need larger coils to handle that level of power.

Ironically, most people that buy the larger coils do so because they are using low-power SET amplifiers with relatively high output impedance, and they want to reduce any additional DCR. But the benefits of lower DCR can be beneficial in high-power circuits too. It sure doesn't hurt.

As for listening, I must admit that I spent most of my time making measurements and only listened for maybe an hour. I can tell that the drivers are very good, but I haven't done the next thing that I like to do, which is to live with them for a while.

I have found that after all measurements are done and a design is "dialed-in," I like to live with it for quite some time. It's not enough for me to just listen to a song or three. That's important, sure, and that's the part I've done. I've listened to the songs that are sort of litmus tests for me, the songs with nuances I especially want to hear. Like listening for the double bass note in "I've Seen All Good People" by Yes. Or listening for throatiness in male vocals and breakup in wind instruments. Michael Buble and Chris Botti are good for those. In each of those kinds of listening tests, the new drivers sound great. No throatiness, no midrange breakup and clean distinct bass.

But I also like to live with a speaker for months and see how it sounds over time. I listen for the occasional odd sound that I never heard before. I listen for breakups or screeches. I listen for anything unusual that shouldn't be there. Sometimes, I find those after a long time. Not very often these days, and not with the larger manufacturers that have good quality control. But I have run into that from time to time, especially from low-production run companies. I've also seen unit-to-unit variations from smaller shops, but again, not from the companies we're working with here, which are JBL, Eminence and B&C.

One other thing I learn only after an extended period of time is the level of listening fatigue. Most of us have been to a concert that was so loud we noticed we had temporary tinniuts after we left. But I think few of us have experienced the same thing from exposure to a lower volume level from a longer period of time. This is something I've learned, and I first found it after a three-day trade show.

What I found is that speakers without shorting rings often sound great to me for an hour or two. I can't tell the difference between the speaker with a shorting ring and another similar driver without the shorting ring. I can measure the lower distortion, but when listening at one or two watts, I just can't hear it.

But when I listen to the speaker all day long for three days - like I do at a trade show - I find that I get temporary tinnitus after the show from the speaker without a shorting ring, even if I've always listened at a moderate one or two watts the whole time. So I found that listening fatigue wasn't just from high power levels, it was a function of time and SPL.

To give a specific example, a four π speaker with an Omega 15 driver sounds great to my ears. I'm not sure that the 2226 really sounds clearer to me. I may think it sounds cleaner, but that might be the psycho-acoustics of my knowing that it measures better, having lower distortion. The truth is that at one-watt, both have such low distortion that it's inaudible, and both sound great.

But if I listen to the four π speaker with an Omega 15 for a whole three-day long show, when I leave the show, I don't really want to play the radio going home. I have listening fatigue and I need a break for a day.

I don't get this listening fatigue from the JBL 2226. I also don't get it from the Eminence Definimax 4012HO in the three π speaker. I've done lots of shows with each of those and left refreshed, and played music on the trip home.

So those are some of the kinds of things I don't know about the new midwoofers yet. I'll only know over the course of time.
Re: Definimax 4012HO - End of Life [message #91087 is a reply to message #91084] Tue, 15 October 2019 06:33 Go to previous message
paulp1960 is currently offline  paulp1960
Messages: 2
Registered: October 2019
Esquire
Many thanks for the detailed reply Wayne. I will get around to ordering crossovers and waveguides from you soon.

Regards,

Paul
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