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Author Topic: Crossing Over Subs at 180 hz  (Read 11315 times)

Mischa Steiner

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Crossing Over Subs at 180 hz
« on: May 03, 2014, 01:27:31 PM »

Hello all,

I found an excellent deal on a pair of Turbsound Flashlight tops, but they need to be crossed over at 180 hz, which is way higher than most tops. I don't have the budget to run a pair of kick bins in between them and the subs.

Is it reasonable to cross subs over around 180 hz? What subs will work crossed over this high and still pound down low? The Danley TH115s say they run up to 200 hz—do they sound good doing it? The only subs I've heard run that high are Voids, Turbosounds and Funktion Ones. Those are all out of my budget unless I get a pair of used F215s on ebay, and I don't think -3 db at 55 hz is going to cut it.

Thanks in advance!
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Art Welter

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Re: Crossing Over Subs at 180 hz
« Reply #1 on: May 03, 2014, 02:15:32 PM »

Hello all,

I found an excellent deal on a pair of Turbsound Flashlight tops, but they need to be crossed over at 180 hz, which is way higher than most tops. I don't have the budget to run a pair of kick bins in between them and the subs.

Is it reasonable to cross subs over around 180 hz? What subs will work crossed over this high and still pound down low? The Danley TH115s say they run up to 200 hz—do they sound good doing it? The only subs I've heard run that high are Voids, Turbosounds and Funktion Ones. Those are all out of my budget unless I get a pair of used F215s on ebay, and I don't think -3 db at 55 hz is going to cut it.

Thanks in advance!
The TH115 will work with a 180 Hz crossover, but front loaded drivers would probably sound better that high.
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Mike Kirby

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Re: Crossing Over Subs at 180 hz
« Reply #2 on: June 24, 2014, 08:34:20 PM »

I feel this question is related to more of a personal assesment of the cabinets themselves, folded subs tend to be quite live at around 160hz, if this is the case then you may be better off crossing them over a little lower to shift the live frequencies into the top cab's. Of course this also depends on the type of crossover and roll off of the crossover points.
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Tim McCulloch

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Re: Crossing Over Subs at 180 hz
« Reply #3 on: June 25, 2014, 07:36:47 AM »

I feel this question is related to more of a personal assesment of the cabinets themselves, folded subs tend to be quite live at around 160hz, if this is the case then you may be better off crossing them over a little lower to shift the live frequencies into the top cab's. Of course this also depends on the type of crossover and roll off of the crossover points.

What is "live" and what does it look like on a technical specification?
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Ivan Beaver

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Re: Crossing Over Subs at 180 hz
« Reply #4 on: June 25, 2014, 07:54:20 AM »

The TH115 will work with a 180 Hz crossover, but front loaded drivers would probably sound better that high.
As usual-everything is a compromise.

The Tapped horn was designed to have a smooth response down low.  The trade off is that higher up-it can get a bit "wonky" with dips and peaks.

The Tapped horn is designed to be used as a sub or generally below 100hz-not a "bass cabinet" as in years past.

Art is right-a direct radiator would sound smoother that high-but not be as loud-so once again there is a tradeoff.

And how much different?  That is in the ear of the user.  To some it may be a big deal-to other no big deal.  It just depends on where the bar is set.

Of course the best way is to simply try it and it may be just fine.

As with many things-there is a lot to the "character" that does not show up on a spec sheet or some simple measurements.
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Mike Kirby

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Re: Crossing Over Subs at 180 hz
« Reply #5 on: June 25, 2014, 05:23:20 PM »

What is "live" and what does it look like on a technical specification?

A peak at the resonant frequency of the cabinet..........It is sometimes difficult for me to place my thoughts into words that others will understand, I have had no technical training but I have 33 years of practical experience behind a desk in a live situation mixing most Australian national acts as well as many international touring bands, I tend to operate by feel than by technical knowledge :)
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Tim McCulloch

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Re: Crossing Over Subs at 180 hz
« Reply #6 on: June 25, 2014, 07:19:33 PM »

A peak at the resonant frequency of the cabinet..........

Thanks, Mike, that helps.

Not sure I'd be interested in a cabinet resonance as part of the desired tone production, but certainly those audible artifacts have to be taken into account in set up and voicing.
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chuck clark

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Re: Crossing Over Subs at 180 hz
« Reply #7 on: August 13, 2014, 11:30:07 PM »

Quote from: Mischa Steiner link=topic=149584.msg1372543#msg1372543 date=139913805 The only subs I've heard run that high are Voids, Turbosounds and Funktion Ones.
[/quote


Huh?  This is kind of a non-issue.  front loaded subs used to respond up to 1 k hz and even old folded horns like the PE 36 Cerwin Vegas were good up to 300 hz.  It wasn't until they started making band pass (one-note) boxes and much heavier moving mass drivers that the higher bass frequencies became diminished in response. It's that bottom octave that's a real challenge.  Heck get you a bunch of old Peavey FH-1's with black widows and give them 600 watts each and they'll knock your legs out from under you @ 80 hz.!  They start rolling off below that so THAT's where things get more difficult.  Relax.  Just about any good double 18 you care to name should work fine for you!
Chuck
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Guy Graham

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Re: Crossing Over Subs at 180 hz
« Reply #8 on: August 28, 2014, 08:00:56 AM »

Hello all,

I found an excellent deal on a pair of Turbsound Flashlight tops, but they need to be crossed over at 180 hz, which is way higher than most tops. I don't have the budget to run a pair of kick bins in between them and the subs.

Is it reasonable to cross subs over around 180 hz? What subs will work crossed over this high and still pound down low? The Danley TH115s say they run up to 200 hz—do they sound good doing it? The only subs I've heard run that high are Voids, Turbosounds and Funktion Ones. Those are all out of my budget unless I get a pair of used F215s on ebay, and I don't think -3 db at 55 hz is going to cut it.

Thanks in advance!

The original high crossover point for Flash and Floodlight tops was based on the limitations of the original processing technology available, when they were first designed over 20 years ago.

I don't recall the details exactly, but you should find more info and modern examples of how folks are currently using these boxes if you search the web. I know a local venue that gets a great sound out of a pair of Floodlights over more modern TSW-218 subs. This works great in a long, narrow room.

The original 180Hz point was used because the slope was lower than commonly used these days - I think 12dB/octave. Hence the corresponding bass boxes were also crossed over at a point that allowed the underlap gap between the bass and low-mid drivers xo points to fill in the frequencies between them.

My experience of folks using Flash/Floods these days is that the low-mid driver in the top box can be crossed over lower than 180Hz, using a steeper slope. Hence you don't need bass boxes/subwoofers that go up that high.

I would query what application you plan to use a pair of Flashlights for? They have a pretty narrow dispersion, as they were designed to be arrayed in multiples. The non-skeletal version's cabinet is built with the correct trapizoidal dimensions so horizontal arrays could be tight packed for consistent coverage.

Sent from my GT-I8160 using Tapatalk 2
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Art Welter

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Re: Crossing Over Subs at 180 hz
« Reply #9 on: August 28, 2014, 04:40:12 PM »

1)The original high crossover point for Flash and Floodlight tops was based on the limitations of the original processing technology available, when they were first designed over 20 years ago.
2)The original 180Hz point was used because the slope was lower than commonly used these days - I think 12dB/octave. Hence the corresponding bass boxes were also crossed over at a point that allowed the underlap gap between the bass and low-mid drivers xo points to fill in the frequencies between them.
3)I would query what application you plan to use a pair of Flashlights for? T
Guy,

1) 24 dB per octave crossovers have been available since the 1970s, and were used for Flash and Floodlight tops.
2) Crossover points in the 180-250 range were common because small mid-bass horns response drops off  below that range.
3) The OP has not been back since May 03, 2014, don't expect your query will be answered, but he wanted high efficiency for an off-grid application, an "Art Car" to be used at the Burning Man Festival, taking place Aug 25 - Sept 1, 2014.

Art
« Last Edit: August 28, 2014, 04:47:18 PM by Art Welter »
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Guy Graham

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Re: Crossing Over Subs at 180 hz
« Reply #10 on: August 28, 2014, 06:08:37 PM »

Guy,

1) 24 dB per octave crossovers have been available since the 1970s, and were used for Flash and Floodlight tops.
2) Crossover points in the 180-250 range were common because small mid-bass horns response drops off  below that range.
3) The OP has not been back since May 03, 2014, don't expect your query will be answered, but he wanted high efficiency for an off-grid application, an "Art Car" to be used at the Burning Man Festival, taking place Aug 25 - Sept 1, 2014.

Art

Thanks for correcting me Art - I'll have to be more careful in future about accepting information from supposed experts without question!

I still see a few Floodlight rigs going, but never with what I understood was the original matching bass cabinet. The sound quality has varied as much as the variety of subs I've seen used.

I assume what I was told about the old 21" & 24" Turbo sub drivers being very expensive to replace/recone is correct?

I did think I had read in threads both here and SF.net that some users were crossing over a fair bit lower than 180Hz, when using different processing to the original provided by Turbosound. Is that possible or another thing I've  misunderstood?

Many thanks for correcting my misinformation, Guy

Sent from my GT-I8160 using Tapatalk 2
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Ivan Beaver

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Re: Crossing Over Subs at 180 hz
« Reply #11 on: August 28, 2014, 08:01:34 PM »



I assume what I was told about the old 21" & 24" Turbo sub drivers being very expensive to replace/recone is correct?



I heard a number of years ago I heard (but cannot confirm) that it around $600 to recone them.

They are very impressive looking drivers.  I have never reconed one.

I doubt that helps much-but is all I can offer
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Guy Graham

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Re: Crossing Over Subs at 180 hz
« Reply #12 on: August 28, 2014, 09:11:54 PM »

Thanks for the info!

Out of interest, could you expand on what you describe as "impressive"?

Also just to clarify another area where my understanding may not be correct - is it not the case that a modern high-power 21" driver has TS parameters with a much greater Xmax than a much older driver such as the Turbosound sub in question?

Many thanks, Guy

Sent from my GT-I8160 using Tapatalk 2
« Last Edit: August 28, 2014, 09:14:13 PM by Guy Graham »
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Ivan Beaver

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Re: Crossing Over Subs at 180 hz
« Reply #13 on: August 28, 2014, 09:20:43 PM »

Thanks for the info!

Out of interest, could you expand on what you describe as "impressive"?

Also just to clarify another area where my understanding may not be correct - is it not the case that a modern high-power 21" driver has TS parameters with a much greater Xmax than a much older driver such as the Turbosound sub in question?

Many thanks, Guy

Sent from my GT-I8160 using Tapatalk 2
The magnet is REALLY large.

Just because a driver has more xmax does not mean it will work properly in a horn cabinet.

The Turbos are short horns-and don't work like a "normal horn".  So the parameters will be different.

Also just because a driver has a larger diameter does not mean that it will have a deeper low freq response.  In fact if you look at most of the 21" sub cabinets on the market you will find that the unprocessed response does not go very low.
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Ivan Beaver
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Art Welter

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Re: Crossing Over Subs at 180 hz
« Reply #14 on: August 29, 2014, 11:55:57 AM »

I did think I had read in threads both here and SF.net that some users were crossing over a fair bit lower than 180Hz, when using different processing to the original provided by Turbosound. Is that possible or another thing I've  misunderstood?
Guy,

"Some users" do things that are simply wrong, crossing below a horn's Fc would be one of those things, even though it is very possible (and easy) to do.

Without seeing the measured raw response of the particular Turbosound cabinet, I really can't say whether 180 Hz is too low, but if the original crossover point was higher, there was a good reason for it.

Art
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Guy Graham

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Re: Crossing Over Subs at 180 hz
« Reply #15 on: August 30, 2014, 06:20:54 PM »

The magnet is REALLY large.

Just because a driver has more xmax does not mean it will work properly in a horn cabinet.

The Turbos are short horns-and don't work like a "normal horn".  So the parameters will be different.

Also just because a driver has a larger diameter does not mean that it will have a deeper low freq response.  In fact if you look at most of the 21" sub cabinets on the market you will find that the unprocessed response does not go very low.

Ivan, I think I understand a bit better now...

The Turbo driver is impressive as it has a very large magnet and voice coil, so has good Bl - which is a more significant TS parameter in this case, compared with Xmax for example.

The "short horn" is compromised by the flare length. The benefit of acoustic pressure created by the sealed rear chamber is maximized by the capabilities of this driver.

Hence this design produces a substantial output and remains efficient. However it does so in a more compact box than a conventional horn design, so there must be a compromise here...

Apologies for throwing my work out and expecting others to go to the trouble of correcting it - I'll not be offended if you just suggest I go and study some more!

Thanks for your patience, Guy

Sent from my GT-I8160 using Tapatalk 2

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Ivan Beaver

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Re: Crossing Over Subs at 180 hz
« Reply #16 on: August 30, 2014, 07:03:18 PM »

. However it does so in a more compact box than a conventional horn design, so there must be a compromise here...

The compromise is low freq extension.  In order to get low freq out of a horn it has to be long with a large mouth.  No way around that.

When the mouth is to small-the driver does not have a good "acoustical transformation" between the driver and the air.  So the response gets ragged down low.

When you add multiple horns together, they all "work together" to form a larger mouth, so the response "fills in" making it flatter to where it should be. 

While the actual response may go lower (but nowhere near as much as people would like to think), usually a Hz or 2, it is the fact that the "ragged response down low" fills in that makes people "think" it goes lower in multiples.  But in reality it is just smoother/flatter down to the cutoff.

HOWEVER it is my "understanding" that the "turbo device" does not work like a normal horn with regards to loading.

I remember reading back in the 80s that the engineers at Turbo sound had heard about the advantages of horns-but did not understand everything involved in how the concept worked.

So they came up with their own "idea", which was carried across to all of the products-just different sizes for different drivers.

I am just repeating what I remember and cannot comment on how well the "turbo device" works or doesn't work as I have only limited direct experience with them.

But I am not aware of other people who are using the same concepts to build bass horns.  Even in the DIY community that works real hard a copying designs that have been proven to work.  For example taking a "concept" and adding their own "twists" to it (different drivers-different horn flares-different throat loading etc)
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jason misterka

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Re: Crossing Over Subs at 180 hz
« Reply #17 on: August 31, 2014, 12:46:27 AM »

We still have twenty of the TSW-721 boxes and use them often.

From a conversation I had with our Turbosound rep probably fifteen years ago, these subs were not designed to be used in a stack of less than six.  I use them in smaller stacks when necessary but understand that there are compromises  of course. 

There are better subs out there but these have great dimensions for truck packing in different sized truck boxes.  They are also very flexible with regard to stacking options for point source PA, and for making fun cardioid or endfire arrays.

We also cross them over at 80hz or 100hz now, since we don't have Floodlights anymore. Even crossed at 80hz they put out plenty of out-of-band information between 150-200 that often needs a little attention.

Downside is the repair.  Avoid whenever possible. Shipping those magnets to a reconer can be very expensive.  The good news is that in the last six months, Turbosound parts and service has become a real asset again and have had everything I have needed in stock in the US.  There were some dark days previously....
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ProSoundWeb Community

Re: Crossing Over Subs at 180 hz
« Reply #17 on: August 31, 2014, 12:46:27 AM »


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