Looking for Powerful LFE? - Enter the DIY GJallarhorn Sub

[Mushroom01]

That's right, if you only want to use one 18" driver, extract some of the loudest, cleanest, LFE bass in the 16 - 60Hz range...... then this DIY project could be for you!

This could be the ultimate anchor sub for punchy, higher frequency subs?

 

 

Built & tested by Data-Bass.com back in 2011, it certainly packs a punch. Also designed to fit a 21" driver!

http://www.data-bass.com/data?page=system&id=45

 

 

 

 

It's like.........putting a Lion in a cage......then poking it......continuously...... with a cattle prod....  

Put one of the best performing 18" subs (TC Sounds LMS Ultra 5400) available from the year 2011, into a low tuned, Tapped Horn and here's the results.

 

 

Further measurements Listed at the below link.

http://www.data-bass.com/data?page=system&id=45&mset=42

 

If you want powerful LFE....You can't tell me it's not a tempting DIY project....   No, i won't be building it........i like my house on it's current foundations... One sealed 18" & a BF table Tuba is enough for me thank you....

Edited November 24, 2016 by Mushroom01

[jamiebosco]

Yeah, they put out some huge bass....122dB at 20hz at 5.6% distortion is incredible for one sub!

[Guest Peter the Greek]

I'm yet to hear a horn sub that I dont notice/hear noise at the port/vent.......perhaps they haven't been calibrated 100%, but I must have listened to 3-4 now. Some DIY, but two where Danleys...yeah, must be the set up.....

[megamond]

Be interesting to compare the same driver in a 6th order bandpass arrangement.

[davewantsmoore]

3 hours ago, megamond said:

Be interesting to compare the same driver in a 6th order bandpass arrangement.

 

A little more (insignificant) output than a vented box, but likely heaps worse ringing and amplifier load.

 

 

I've never been able to move beyond either sealed box, or front load horn.

[megamond]

To my ear, there's a lot to be said for non-pistonic pure Helmholtz resonators, regardless of a waterfall graph, something in the psychoacoustics picks up the piston IMHO.

 

[almikel]

2 hours ago, megamond said:

To my ear, there's a lot to be said for non-pistonic pure Helmholtz resonators, regardless of a waterfall graph, something in the psychoacoustics picks up the piston IMHO.

 

Hi megamond,

I'm not sure what you're saying?

The maths regarding a typical ported box (helmholtz resonator) is based on the driver acting as a piston.

What is a "non-pistonic pure helmholtz resonator" ?

 

cheers

Mike

[almikel]

5 hours ago, davewantsmoore said:

I've never been able to move beyond either sealed box, or front load horn.

Hi Dave,

I'm assuming Infinite Baffle would be in there somewhere?, and Front Loaded horns get too big at low freq?

 

On 11/24/2016 at 9:21 PM, Peter the Greek said:

I'm yet to hear a horn sub that I dont notice/hear noise at the port/vent.......perhaps they haven't been calibrated 100%, but I must have listened to 3-4 now. Some DIY, but two where Danleys...yeah, must be the set up.....

Hi Peter,

you may be right - esp if you've heard 2 x Danleys that demonstrate that...

 

My tapped horn sub doesn't seem to add noise, but it might be.

At the listening position you can tell easily whether the sub is on or off.

At he listening position you can't locate the sub - all the bass "appears" to come from the main speakers.

When you put your ear close to the mouth of the horn, ihe output is very clean - but who can determine a "horn sound" at 20-50Hz????

 

cheers

Mike

 

 

 

[davewantsmoore]

15 minutes ago, almikel said:

I'm assuming Infinite Baffle would be in there somewhere?

 

It's a sealed box.

 

16 minutes ago, almikel said:

and Front Loaded horns get too big at low freq?

 

They do get big, although in small rooms (boundary loading) they can be made smaller than the math says.

 

20 minutes ago, almikel said:

who can determine a "horn sound" at 20-50Hz????

 

 

It can be very hard to tell on program material  (cos you don't know what it is supposed to sound like, and you end up choosing what you "like").

 

Measurements can show the ringing....  but generalisations are very difficult.  Where the bandpass filters are placed, and the room, both have an enormous effect.

 

[Nada]

28 minutes ago, davewantsmoore said:

They do get big...

[megamond]

"The maths regarding a typical ported box (helmholtz resonator) is based on the driver acting as a piston."

 

Not in a 6th order bandpass and above, the driver diaphragm doesn't interact directly with the room at all, it's a completely helmholtz cavity interaction with the room.

It may be a backwave issue - I'd have to try a TL or tapped horn, as open baffle and quasi open baffle sound reasonably OK IMHO.

If you listen to live music often and compare e.g. the kickdrum across the subwoofer to mains there are incredible dynamics, particularly if using low compliance (tight suspension) mains, will really test the subs.

Doubtful many home systems would stay with a modern 15" PA main capable of f3 40Hz and efficiency c. 100db/W that Cerwin Vega approached a while back (or 15" JBL studio monitors).

Ditto a double bass - as someone once said - have you heard an actual double bass played in a home?

 

[almikel]

 

 

 

2 hours ago, almikel said:

Hi Dave,

I'm assuming Infinite Baffle would be in there somewhere?,

 

1 hour ago, davewantsmoore said:

It's a sealed box.

Pure gold - a sealed box of infinite size - but the neighbours may not approve when they discover they're inside the box 

 

1 hour ago, davewantsmoore said:

Measurements can show the ringing....  but generalisations are very difficult.  Where the bandpass filters are placed, and the room, both have an enormous effect.

 

agreed

The outdoor measurement of my tapped horn sub shows significant ringing at 90Hz or so as expected (and 50hz power supply hum)

 

In the room, I run the sub with a 48dB low pass Xover at 50hz.

The waterfall below is taken at the listening position.

As expected the sub gets much lower in the room.

The low pass takes out the ringing at 90Hz - although there's something going on around 73Hz (down near the noise floor).

 

This is not the current setup, but early curves of the sub in the room - I've tweaked EQ since then to get a smoother response - I can't find the files on this PC.

 

Mike

 

 

 

 

 

[almikel]

21 minutes ago, megamond said:

"The maths regarding a typical ported box (helmholtz resonator) is based on the driver acting as a piston."

 

Not in a 6th order bandpass and above, the driver diaphragm doesn't interact directly with the room at all, it's a completely helmholtz cavity interaction with the room.

 

Ok - I understand what your saying - but even with a "6th order bandpass and above" the driver is still interacting with the room via the transfer function of the speaker in the room. The helmholtz cavity connected to the room is also connected to the driver and becomes part of the overall transfer function of the speaker.

 

48 minutes ago, megamond said:

It may be a backwave issue - I'd have to try a TL or tapped horn, as open baffle and quasi open baffle sound reasonably OK IMHO.

 

compared to "6th order bandpass" ?

I'd expect both open baffle and quasi open baffle (I'm not sure what quasi means in this context) to sound very different to a "6th order band pass" sub in a room - they have very different radiation patterns.

 

An open baffle will have a dipole radiation pattern - not very effective for sub frequencies "in room" as the front wave interacts with the back wave to cancel each other.

 

A "6th order bandpass" with a single outlet, or direct radiator (sealed), or front firing ported direct radiator, or tapped horn, or front firing TL - all will be omni directional at sub frequencies...although a "6th order bandpass" may have some funky stuff going on in both directions - as with rear firing ports, everything gets more complicated...

 

1 hour ago, megamond said:

 

Doubtful many home systems would stay with a modern 15" PA main capable of f3 40Hz and efficiency c. 100db/W that Cerwin Vega approached a while back (or 15" JBL studio monitors).

 

YMMV, but I've not come across any Pro drivers that can maintain an efficiency of 100dB/W down as low as an f3 of 40Hz once they're in a box.

Sure most pro drivers can get to 40Hz in a box (sealed, ported, or "6th order bandpass") - but they need EQ and they sure aren't 100dB/W down there.

 

I run Acoustic Elegance TD18s as my mid bass - 98dB/1W/1m  - an F3 in my boxes around 95 Hz - I push them down to 40Hz or so with EQ - thay ain't 98dB/1W/m down there. Not many (any) Pro drivers are.

 

 

cheers 

Mike

 

[megamond]

"Ok - I understand what your saying - but even with a "6th order bandpass and above" the driver is still interacting with the room via the transfer function of the speaker in the room. The helmholtz cavity connected to the room is also connected to the driver and becomes part of the overall transfer function of the speaker. "

 

Yes, I'm aware of equivalence circuits, but that's basically looking at the input, not the output.

 

Horns and TL's are matching the driver's acoustic impedance to the room (solid to gas); a tapered horn-like port (2 of) on a 6th order bandpass (dual ports in push-pull alignment not unlike the JBL TCB) - e.g. the Nexo bandpass subs, now in 12' and 15".

'6th order' is the efficiency factor, mathematically.

 

Of course, a tight suspension 15" main is not flat to 40Hz; the 80Hz plus octave is what conveys bass 'power', as I'm sure yours do, and in-cabinet the efficiency will be well above 90dB/Watt/m in this region - with power handling of hundreds of Watts, leaving home subwoofers in the dust.

 

[davewantsmoore]

17 hours ago, megamond said:

have you heard an actual double bass played in a home?

 

Indeed.   This is why I tend to believe that a decent home systems needs to be ~100dB/w @40hz.

 

17 hours ago, almikel said:

although there's something going on around 73Hz

 

 

Some type of rattle/buzz?!?

[davewantsmoore]

15 hours ago, almikel said:

I'd expect both open baffle and quasi open baffle (I'm not sure what quasi means in this context) to sound very different to a "6th order band pass" sub in a room - they have very different radiation patterns.

 

There is no "radiation pattern" as such, at bass frequencies - it is just the modal excitement in the room.

 

The differences as to how a mono and dipole excite the steady state modal field are over-exaggerated.....  although there are some other differences which makes the "envelope modulation" performance of a dipole, superior....   OTOH, a dipole is less efficient at low frequencies.

 

Really.... The key is sufficient efficiency, and then good placement and EQ.   The things that "typical" systems do not have (usually at all).

[davewantsmoore]

17 hours ago, almikel said:

efficiency of 100dB/W down as low as an f3 of 40Hz once they're in a box.

 

Indeed.   I was assuming multiple drivers.

 

I have 7 speakers playing 40Hz.     5 sealed boxes (pretty low efficiency), and 2 front loaded horns  (which are more than -6dB by then,  as they're 50Hz horns).

Edited November 28, 2016 by davewantsmoore

[megamond]

55 minutes ago, davewantsmoore said:

The key is sufficient efficiency, and then good placement and EQ

Precisely.

[almikel]

On 11/28/2016 at 3:52 PM, davewantsmoore said:

 

Some type of rattle/buzz?!?

yes lots of those unfortunately - windows/room - I only notice them when running tones/woop woops

 

On 11/28/2016 at 10:11 AM, megamond said:

the 80Hz plus octave is what conveys bass 'power', as I'm sure yours do, and in-cabinet the efficiency will be well above 90dB/Watt/m in this region - with power handling of hundreds of Watts, leaving home subwoofers in the dust.

 

I was so blown away with the bass "slam" delivered by my TD18 mid bass drivers that I didn't consider a sub necessary until I listened to another SNA member's setup that hit 20Hz easily - actually made the hairs on my neck stand up on some organ music.

As you say, that bass slam isn't at sub freq, but the after building the tapped horn sub, the weight in that bottom octave is something you don't want to give up - you hardly know it's there, until you turn the sub off (music dependant of course).

 

On 11/28/2016 at 3:52 PM, davewantsmoore said:

 

Indeed.   This is why I tend to believe that a decent home systems needs to be ~100dB/w @40hz.

with sub or subs and mains adding to the mix, how would you go about determining if you were achieving this goal? (genuine question) - and is the main concern thermal/power compression so decent dynamic range in the 40Hz range (edit) isn't compromised?

On 11/28/2016 at 3:58 PM, davewantsmoore said:

The key is sufficient efficiency, and then good placement and EQ.   

 

On 11/28/2016 at 4:54 PM, megamond said:

Precisely.

I agree also, but then the differences in the type of speaker (sealed/ported/tapped horn) should become less important if efficiency/placement/EQ is managed - obviously no easy task:

• sealed and ported boxes may require multiple drivers/boxes to increase efficiency
• tapped horns get big and front loaded horns get really big at low freq

In my (limited) experience, subs sound the same once EQ'd the same (assuming no port chuffing or driving beyond capabilities) so regardless of type, once the efficiency/placement/EQ is sorted (I'm assuming this includes time alignment and integration with mains) then a successful outcome should be possible with any sub/subs?

 

Hoffman's iron rule works against us - my large tapped horn sub (2400x400x300mm) has limited placement options in my room, but has good efficiency (the plan to mount it outside the room hasn't quite been executed  ).

My tapped horn has 2 x 12" drivers and has the output of 8 or so similar drivers in sealed boxes (with bigger amps)

http://redspade-audio.blogspot.com.au/2012/02/how-does-sensitivity-of-tapped-horns.html

• Fitting 8 sealed boxes into the room would be a challenge.
• Fitting 8 ported boxes harder.
• Infinite baffle takes up least room, but you need to get placement right on the first try (or get good at patching holes) - and deaf or very understanding neighbours ...

 

I think many sub options can work very well, and it's not so much which sub or type, but the effort spent in integration that makes the difference - and efficiency/placement/EQ is a big part or good integration.

 

cheers

mike

 

 

 

 

Edited November 30, 2016 by almikel
typo

[megamond]

On 30/11/2016 at 11:45 PM, almikel said:

I was so blown away with the bass "slam" delivered by my TD18 mid bass drivers that I didn't consider a sub necessary until I listened to another SNA member's setup that hit 20Hz easily - actually made the hairs on my neck stand up on some organ music.

As you say, that bass slam isn't at sub freq, but the after building the tapped horn sub, the weight in that bottom octave is something you don't want to give up - you hardly know it's there, until you turn the sub off (music dependant of course).

Definitely - there's two octaves below 80 Hz that can't be ignored, but 80 Hz gives the 'slam' in the chest (bottom end of the male voice).

IIRC 40-80 Hz gives bass 'deepness' and 20-40 Hz is 'rumble'.

I believe, however, that most music recording is rolled off at 34 Hz to avoid excessive rumble.

 

[megamond]

On 30/11/2016 at 11:45 PM, almikel said:

In my (limited) experience, subs sound the same once EQ'd the same

Interesting.

I've read an Audio Recording Engineer opining that there are two camps of hearing ability - those who can/can't hear the 'missing fundamental' - to my ears, sealed/ported/bandpass all sound different and the bandpass definitely rattles the house the most - it may be the 45 Hz lower tuning lobe coupling with the room/house - comparable to a DD18 in a review.

[almikel]

hi mm,

the room plays such a big part below 80Hz, if you EQ any sub in the room to the same response, IME the differences in sub type disappear.

In your example of a bandpass sub rattling the house most, the "in room" response was likely different.

 

This of course assumes the subs (and amps) you're comparing are capable of the SPL you ask of them.

 

I've always leaned towards sealed and IB due to their lower group delay, but with DSP and the ability to delay the mains, group delay is much less of an issue.

 

I built a Tapped Horn sub (higher group delay to sealed/IB) and I'm happy with the results after integration.

Being very large it just cruises with moderate amps (Hoffman's iron rule applies), but IMHO, any other sub within it's SPL limits with good integration could achieve the same outcome - YMMV.

 

cheers

Mike

 

 

 

 

[davewantsmoore]

11 hours ago, almikel said:

the room plays such a big part below 80Hz, if you EQ any sub in the room to the same response, IME the differences in sub type disappear.

 

In broad terms, this is very true.

 

The reason is that before the subwoofers are placed in the same location, and EQed to the same response .... they are so incredibly different in response,  that reason they sound different is not so much because they are sealed, ported, horn, etc......  it is because of the enormous differences in response caused by the (lack of) EQ/placement.

 

Of course, all of this is for subwoofers that are operating where this is no significant distortion (which could tell them apart from each other)..... which is obviously not always the case.

[megamond]

On 16/12/2016 at 11:04 AM, davewantsmoore said:

Of course, all of this is for subwoofers that are operating where this is no significant distortion (which could tell them apart from each other)..... which is obviously not always the case.

Was reading a forum on a PPSL 6th order saying that the 6th order acoustic filtering gave a cleanness they hadn't heard before and so IMHO 6th order bandpass is the same, distinctive of EQ.

http://www.audioasylum.com/cgi/vt.mpl?f=hug&m=150804&VT=T

[davewantsmoore]

Yes.  The acoustic low pass filter will remove any distortion products (high frequencies) created by the driver.    Ideally you would not have the in the first place, of course.

 

These type of enclosures are incredibly difficult to design well IMHO.    The allure of the sealed box, or front loaded horn is still very strong