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Not satisfied with my 8 RCF 4Pro subwoofers, need help going lower.
Not satisfied with my 8 RCF 4Pro subwoofers, need help going lower.
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Old 6th January 2019, 10:31 PM   #1
Jay Michael is offline Jay Michael  Canada
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Default Not satisfied with my 8 RCF 4Pro subwoofers, need help going lower.

Greetings everyone. We host a festival 10 years running in Alberta Canada plus host periodic indoor events. Our current fleet of 6 - RCF 4Pro4001 tops and 8 - RCF 4Pro 8001 subwoofers have served us well over the last 10 years but our musical preferences have evolved over the decade and we are finding our subs just don't go deep enough for some of the modern bass music some of our artists play, they really just fall flat below 40hz or so. Our crowd coverage for the most part maxes at 300 people, typical would be 150-250 people for most shows.

Looking for advice on how to reinforce our system to cover those lower frequencies. Our current system sounds fantastic for house, techno and live music, I am not interested in selling the system and starting over with something new (couldn't afford it, mortgage, kids etc). I'm 25 years into this game and I doubt we have many years left hosting events and what we would get for our system probably wouldn't get us much new modern gear.

So whats my options here? Can I build something to compliment what I already own? Something that could just cover the really low stuff, 25 to 40 hz or so? I know this is not an ideal way to deal with this problem but I'm looking for opinions if its possible and if so what should I be looking for in plans. My subs are bass reflex so I would assume I should stay with bass reflex projects... or would it be possible to use a folded horn design? I know time alignment would be required.

Thoughts? Opinions anyone? Is this a fools idea?

Thanks ahead to anyone willing to chime in
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Old 7th January 2019, 12:19 AM   #2
GM is offline GM  United States
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The most obvious I guess since not familiar with active subs is to buy [8] more of them, all [16] stacked as a central sub system or at least stacked across the floor to create a line array to drop the system a 1/2 octave [0.707*40 = ~28.28 Hz].

Another would be a couple of simple tapped horns using one or more [each] of the latest version of these that apparently load DSL's one off [AFAIK] Matterhorn: https://www.mtx.com/9515-22-car-audio-subwoofer

danley matterhorn - Google Search

Having had some experience with MTX, if the RCFs have good enough resale value, I'd build some ~20-80 Hz THs and sell off some/all to fund them depending on if you'll need any mid-bass 'fill'.

GM
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Old 7th January 2019, 01:40 AM   #3
weltersys is offline weltersys  United States
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Quote:
Originally Posted by Jay Michael View Post
1)Can I build something to compliment what I already own? Something that could just cover the really low stuff, 25 to 40 hz or so?
2)My subs are bass reflex so I would assume I should stay with bass reflex projects... or would it be possible to use a folded horn design? I know time alignment would be required.
3)Thoughts? Opinions anyone? Is this a fools idea?
Jay,
1) According to the RCF spec sheet, the 4Pro8001 rolloff begins at 60 Hz, and is around -10 dB at 45 Hz, so there is definitely another octave extension below their tuning frequency required to reach down low, which does make a case for a dedicated sub-system for house & techno EDM.
2) Bass reflex could get the job done, but tapped horns being around 6 dB more sensitive could do it with about half the power and driver count, though would require slightly more cabinet size. Since cost is obviously an issue, TH are the way to go, unless you have room for even larger FLH (front loaded horns).
3) Having used my Keystone tapped horn design for some EDM music, I've found that the response to 35 Hz was a good compromise between size and extension. I've not heard a lot of music where the lack of <35 Hz makes much difference, but it is becoming more common now.
If you want to get down to a bit below 30 Hz, Josh Ricci's Othorn would give similar output, but costs considerably more in drivers, amplification, size & build complexity. To make it to 25Hz, Josh's Gjallerhorn would do the trick, again at another large increase in drivers, amplification, & size.
Any of the three TH designs could make 100 Hz, making the 4Pro8001 redundant.
If using the Keystone or the Othorn, the extra crossover point would just make typical set up more complex, and I would not bother with using both.
The Gjallerhorn would be my choice if actually wanting to split the <100 Hz range in two.

Even though the LF response of the 4Pro8001 is lacking, the 50-80Hz "punch" will continue to make it a viable small system sub, you could probably finance some to most of an upgrade (depending on how low and loud you decide to go;^) ) selling them after completion of a more capable sub-system.

Art
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Old 7th January 2019, 04:30 AM   #4
Jay Michael is offline Jay Michael  Canada
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GM, thanks for your thoughts. Your first comment for sure went over my head. How would an additional 8 subs get me down to 28hz? Am I not limited by the design of boxes? Ill take a look at your other suggestions, thanks for those. One of my fears around switching to different boxes outright is the loss of the nice mid bass punch these RCF units have. In my research it seems there is often a trade off when getting something that can play down to 35 or 35 hz you probably loose that punchier mid bass performance.... As such Im trying to research if there is a reasonable option to integrate other subs into my current set up... sort of a mid bass, sub bass two way scenario. When I first purchased these subs the style of music we were all really into demanded that mid bass punch and they really do sound awesome for that... Id hate to loose it as we still program a bunch of that sound at our events.

Weltersys. Thanks for chiming in, digging into your suggestions now. Your keystone sub looks pretty interesting, and wow over 100 pages to read through haha! As I replied to GM perhaps I am looking for a subwoofer solution that doesn't exist? These RCF subs really punch nice for progressive trance and techno which is why I bought them in the first place. Its just frustrating to hear some bass music tracks playing on them where I can tell they are missing much of those deeper notes. If my only solution is dump the RCF's to finance something more applicable I guess I could list them up to see if there is any interest, they are pretty minty still... But still hoping to find an alternative solution where I could invest perhaps 2-3k into some cabinets that could integrate into what I already have.... Just not sure if thats feasible. I have come across a few companies in the home hifi world that offer a mid bass and sub bass complimentary set of components to do what Im looking for. The search continues
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Old 7th January 2019, 09:00 PM   #5
chris661 is offline chris661  United Kingdom
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I'm not sure I see how they'd get down to 28Hz, either. They're ported boxes, so the tuning frequency is fixed by internal mechanics.

+1 on Art's suggestions of looking at tapped horns.
Your main speakers have a 15" bass driver, so I think the Orthorn would be the way to do it.

Chris
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Old 7th January 2019, 09:26 PM   #6
GM is offline GM  United States
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Much greater acoustic coupling efficiency allows significant EQ shaping, making it quick/easy to gain some extra LF, though of course it's not cost efficient, so would be better overall to have all cabs tuned to ~28.28 Hz in such a system and best overall to switch over to TH or similar as either a standalone sub system or partial/complete wide range replacement.

**WRT EQ, etc., electronics, this is what Danley Sound Labs [TH inventor] uses AFAIK: Xilica | Networked Audio DSP & Control Solutions

Don't keep up with the various prosound build threads, so can't help there beyond designing from scratch with driver specs based on desired bandwidth, peak SPL.

GM
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Last edited by GM; 7th January 2019 at 09:32 PM. Reason: **
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Old 8th January 2019, 08:44 AM   #7
chris661 is offline chris661  United Kingdom
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Quote:
Originally Posted by GM View Post
Much greater acoustic coupling efficiency allows significant EQ shaping, making it quick/easy to gain some extra LF, though of course it's not cost efficient, so would be better overall to have all cabs tuned to ~28.28 Hz in such a system and best overall to switch over to TH or similar as either a standalone sub system or partial/complete wide range replacement.
Even for ported boxes..?

I managed to fold the cone on an expensive driver by driving it hard below tuning, so I'd really hesitate to try to get those RCF boxes to go to 28Hz.

Chris
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Old 8th January 2019, 09:09 AM   #8
steveu is offline steveu  United States
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A ported box sacrifices any output below resonance in order to produce a strong flat bass down to resonance. Professional high efficiency drivers are not designed for super low frequencies. There are problems with large room acoustics at lower frequencies so they are often deliberately removed, so a Thiele-Small ported box is usually a great choice. But if you actually want <60Hz bass, a sealed box is the simplest thing. A transmission line box is the only thing that extends a driver range below resonance, but such things are not portable. There have been drivers larger than 18" that may give you what you want, but they are not efficient and will not make high sound levels. A horn for 40 Hz would have to be ~16 feet wide, ~32 feet for 20Hz.

Thiele/Small parameters - Wikipedia

BTW, I fixed amps in Edmonton back in the 80's. While I loved the work, it just didn't pay.

Last edited by steveu; 8th January 2019 at 09:23 AM.
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Old 8th January 2019, 01:08 PM   #9
chris661 is offline chris661  United Kingdom
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Quote:
Originally Posted by steveu View Post
But if you actually want <60Hz bass, a sealed box is the simplest thing.
Having actually tried using sealed boxes for PA systems, my recommendation is this: don't.

Sealed boxes leave a lot of output on the table. Run the simulations and see what you think.

Chris
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Old 8th January 2019, 10:25 PM   #10
Think is offline Think  Netherlands
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Not satisfied with my 8 RCF 4Pro subwoofers, need help going lower.
Boost 3dB @40hz, cut 10dB from 50hz up and run them with more power or put them together in a corner or at least against a wall.


// the rolloff is so big, stuff the ports with socks/towel (the tuning will go down) or close it completely.

Last edited by Think; 8th January 2019 at 10:38 PM.
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