Getting a warm sound? (with simulations)

The quantity and character of a subwoofer’s distortion determines how “warm” it plays, unless we’re talking about the overall tonality of the system, which depends on more than the just the sub.

Edited by Randy Bohannon - 09 December 2022 at 4:52am

Thank you very much for answering my post. I'm especially happy that each of you is addressing the subject from a different angle.

Levyte, I was hoping for a reply like yours. People on this forum have described the sound of the PD1850 in Superscoopers as hard or boomy (though some seem to like it). Thank you for confirming that.
How much can I rely on simulations? Are they accurate enough that if I see strong resonances like the ones in my picture I can expect a certain sound? Or is a simulation too far off reality to make guesses?

People report that sometimes they had a speaker that looked great in simulation but they were disappointed by the results from the real speaker. I guess I could live with that as long as simulation got me into the right direction.

Vertx, thank you for pointing out that a warm sound comes from the way a whole system plays together. What do you mean by dispersion? I found that the bass in sound systems can sound very different from system to system. Some sound systems have beautiful strong basses but I wouldn't say they sound very deep. Is that from an emphasis on upper bass?

Yes, there are some speakers with fairly constant Bl over a wide range of excursion. Compliance is less constant. Would you say a change of compliance will cause harsh distortion inside the range where Bl is still high?

Randy, this is excellent information. So something with moderate low order distortion would be good. Thank you very much. From what I hear, drivers in subwoofers can exceed 10% of distortion more quickly than I would have guessed. Going lower might be difficult.

I don't wish to criticise how other sound systems sound. One of the good things about Reggae sound systems and about scoops is the variety people achieve with a similar kind of setup. I love hearing sound systems who sound a lot different from the sound I'm going for.

I started reading this forum from end to end in early autumn. There are a lot of posts I don't understand due to my lack of information and experience. I appreciate any input you can give me.

Best wishes
Axel

Hmm. So Randy Bohannon had some simulation results that had at least some resemblance with reality while Levyte357 and others found that results are often way off. I will definitely listen to what people tell me about their experiences with scoops.

Here's a question that keeps bugging me: Some people love scoops for their warmth and others love them for their grunt. People design their speakers to give them the character they prefer but I don't understand why both things are possible with the same type of loudspeaker. Now I found a post by Disco Stu in this thread:

https://forum.speakerplans.com/what-is-the-fault-with-scoops_topic12733_post118339.html

It's the eighth post.

He writes that the direct radiating output from a scoop gives audible distortion that emphasizes the upper bass and the horn output gives a deep tone.

Are there scoop designs that lean more into one or the other direction? Or is there a way to modify a design to make it balance direct and horn output differently without getting a bumpy frequency response?

We are using a JBL DSC260 crossover/limiter/eq that we like very much. We also have a parametric EQ we haven't tried out on our sound system yet.

Best wishes
Axel

levyte357- wrote: Twinkle wrote: Thank Levyte, I was hoping for a reply like yours. People on this forum have described the sound of the PD1850 in Superscoopers as hard or boomy (though some seem to like it). Thank you for confirming that. How much can I rely on simulations? Are they accurate enough that if I see strong resonances like the ones in my picture I can expect a certain sound? Or is a simulation too far off reality to make guesses? Axel With regard to Scoops, simulations are a waste of time. Read the Scoop forum, to find nuggets of info, from experienced Scoop system owners, not armchair experts, who never go to Reggae gigs, but ready to quote research papers and simulations. Sound you will get, depends on combining drivers  with right cabs, then suitable amp for the drivers. Then you need quality pre-amp, to shape/add desirable sub warmth. I prefer bass pre-amp AND LMS. Above is just the start, no sims in sight !!!

Spoken like someone who, unfortunately, correlates their inability to understand what’s occurring acoustically to using models properly.

Scoops are not some magical device that defies all logic and >100 years of research and understanding by people far, far smarter than us. In fact, the transmission line is one of the most well-understood concepts in sound.

As I’ve stated many times on here, the bigger problem is that people seem to rarely build what they sim. It’s a cyclical process, refine the model based on what you build, and vice versa. No model will tell you everything that’s happening acoustically, but that’s part of understanding their limitations - and advantages.

It’s a shame some folk have to make out like you need to imbibe some ancient knowledge like a Indiana Jones villain to enjoy them.

Not everyone has a ton of money, time, wood or access to dances & boxes to work purely on trial & error.

To the OP, you can observe the output of the front radiator and horn elements separately in Hornresp. That’s quite handy.
Pick a box & driver combo you have access to listen & hopefully, measure even the electrical impedance of, and work on making the model fit what’s been built.

Then start to correlate behaviours you see in the sim (excursion, group delay, phase angle, magnitude response, etc) with what you hear that you like and don’t like.

Or just spend a fortune on loads of drivers, boxes, and post 100s of winking emojis for years

Again, I wish to thank each of you who has given me advice here. It's good to hear from all the different kinds of experience you've had.

I don't know how to interpret the mocking in this forum. I hope everything is in good spirit.

Levyte, thank you very much for recommending the Wattco Scoop to me. It's intriguing to use something that's both loud and deep-sounding.

I'm undecided about a combination that needs equalisation. We are a loose group of people who will take turns using our stack. It would be good to have something foolproof.

Randy, thank you for encouraging me to use a circuit simulator. I'm starting to write a netlist now.

Some time ago Levyte357 wrote that drivers like the Fane 18XB or the Colossus 18-1000 will work fine in medium to large chamber scoops. People report they had good results with designs like Mykey's Rhino Mk2 and the Eminence scoop. These drivers get criticised for being less loud than higher Bl ones.

We play outdoors in front of less than 100 people. We hope we will have an audience of 300 people from time to time.

The 18XB doesn't have a lot of xmax and the 18-1000 is out of production.

The RNC LF18X401 has parameters that are almost identical to the Fane 18-1000. The only difference is that VAS is higher (274 instead of 238). Does the change in VAS make a great difference? Last week I spoke to a man who designs loudspeaker chassis. He told me no, you can't rely on VAS anyway. What do you say?

Vance Dickason measured the LF18X401 in detail. https://www.yumpu.com/en/document/view/51827472/um12-22-voicecoil-review-by-vance-dickason-dayton-audio
From the article, two samples after break-in, measured two ways:
fs 27.8 Hz ... 31.8 Hz,
Re 5.6 ... 5.7
Sd 0.123
Qms 3.76 ... 5.05 one method, 4.47 ... 5.83 other method
Qes 0.28 ... 0.34
Qts 0.26 ... 0.32
VAS 247.9 ...288.2 one method, 268.3 ... 328.4 other method
SPL@2.83 V 95.5 dB/95.8 dB depending on method
xmax 11 mm

The LF18X401 is also pretty cheap here (290 EUR). We don't make any money with our music so we don't have much we can spend.

There's almost no information on that driver on the scoop forum. People seem to like it in reflex enclosures. Would you recommend that driver to us?