69 replies to this topic

[Paul Spencer]

I've been planning this for ages and I'm not sure when I will get a chance to build this beast, but it will hopefully be soon! This is a tapped horn sub with two Rythmik 12" servo sub kits. On their own the Rythmik subs don't have the same headroom as active 106 db horns. But two of these tapped horn loaded and hidden away under the floor can put out 97 db all the way down to about 15 Hz. So I gain about 6 db sensitivity, which means half as many drivers and half as much power. I've managed to come up with a semi-sane box that is around 400L ... 400 x 600 x 2250mm.



Max SPL



More
http://redspade-audi...d-horn-sub.html

Dual opposed reduces vibration - needed when connected to the floor. I'm planning a hole in the floor under the bass traps.

I might have to use ply this time to keep the weight down. Installing it will be interesting. I have sandy soil and I will have to move it over sand under the house.

[:) al]

holes in the floor ? why not just go IB ? dont think ever come across anything like norpus' IB 18s he had hidden under his floor !

[Paul Spencer]

IB is a low sensitivity option that requires a lot more power and drivers to achieve my goals. 78 db 1w1m @ 20 Hz! .... I think I like 97 dB a lot more

Don't get me wrong, IB is a great option for those who have the budget to buy enough power and driver displacement to hit their targets, but it's not a good match for my system on a budget. With the Rythmik kits, there is also no real performance advantage with IB.

Edited by Paul Spencer, 22 January 2012 - 03:29 PM.

[Drizt]

I agree i reckon norpus IB is as good as it gets, no need for anything more. Its just so clean with more output than anyone would ever need.

[Paul Spencer]

I'm also not keen in half of the output going outside - that is the major downfall of IB. I'm sure Norpus has great subs, but this is my bloody thread!

[:) al]

IB is a low sensitivity option that requires a lot more power and drivers to achieve my goals. 78 db 1w1m @ 20 Hz! .... I think I like 97 dB a lot more

Don't get me wrong, IB is a great option for those who have the budget to buy enough power and driver displacement to hit their targets, but it's not a good match for my system on a budget. With the Rythmik kits, there is also no real performance advantage with IB.

sorry but reading your post paul I have to say ...bulldust ! hehe seriously while yours is a text book answer it doesnt bear out in reality. IB low sensitivity ? norpus' twin 18s were at one stage going off a spare channel of his elektra T7. thats 185w. Last I remember seeing on JAs military grade spl meter was something along the lines of what was it 120-130db ?... and if thinking its all being lost outside the house inside you could ride the floorboards as the bass waves went through or it was maybe my eye balls vibrating I cant remember hehe

for something on a budget you honestly cannot beat IB either !

yeah sure IB not everyones thing, not for me either, but for budget and power needed for displacement I could not disagree with you more

[Paul Spencer]

If you want to debate IB you are welcome to create another thread for it. This is a thread about my upcoming project, not about Norpus' subs.

I already have the subs and they don't meet all of my performance goals, hence this project. There is nothing to be gained from IB mounting these subs. In order to meet my goals, I either need more power and displacement, or horn loading. I've chosen the latter.

In an IB, these drivers would each have 85 db 1w1m or 88 for the pair. The tapped horn version adds 6 db, which is like doubling up at the cost of building the box. I've also been wanting to build a tapped horn for ages, it's long overdue.

sorry but reading your post paul I have to say ...bulldust ! hehe seriously while yours is a text book answer it doesnt bear out in reality.

Norpus, in your example there could be many things going on, but it's not relevant to what I'm doing here.

IB low sensitivity

Yes, it's a simple fact. An IB sub is like a sealed box except the lack of a sealed air spring means less power is generally required compared to a sealed box. However, the sensitivity is no greater and it rolls off like a sealed box. So by 20 Hz you have low sensitivity. Now of course the room will have a massive impact, more so than driver sensitivity, and we will have big peaks and dips as a result. And with various SPL meters you get different results depending on the ability of the meter to deal with peaks and how fast they can register. That isn't my interest here.

If I were to look at things in that way, then someone could probably show from SPL meter readings that an ML1 is all anyone would ever need. My experience indicates otherwise!

for something on a budget you honestly cannot beat IB either !

That isn't true at all. Compared to a vented box you need twice as many drivers for the same result. The only thing about IB that saves any money is the box, but that just happens to be the cheapest part of all! IB is expensive in terms of the drivers and amps - the expensive bits.

In terms of bang for buck, dipoles are the worst, followed by sealed boxes and IB. Horns are in fact the best in this regard because you save on the things that cost most (drivers and amps), and pay for the result with a big box (the cheap part of a DIY project).

yeah sure IB not everyones thing, not for me either, but for budget and power needed for displacement I could not disagree with you more

I'm not anti-IB, it's just that it doesn't make sense here. If I had a bigger budget and no problem with the associated sound leakage, then IB would be a consideration.

[Drizt]

Ib is the ultimate in my book but its not for everyone. Good luck with your project paul. Are you concerned at all at the extremely ragged response at the upper frequencies? That is what puts me off horn subs.

[Paul Spencer]

Ib is the ultimate in my book but its not for everyone.

In the right system, I'd say horn loaded and IB are the two main ultimate sub choices. If you really wanted extreme then you could do a single massive sub bass horn augmented with multi sub IBs. You could have the best of everything.

Are you concerned at all at the extremely ragged response at the upper frequencies? That is what puts me off horn subs.

Not really concerned, this is intended to be a narrow bandpass device anyway, which also reduces the power demand. I may cross as low as 40 Hz. If it were a front loaded horn I could get it smooth all the way up, but there's no way to deal with such a big mouth!

[:) al]

Oh well I butt right out your thread then thanks ! Hehe You never mentioned these a done deal had drivers cabinets the lot . All you mentioned was a plan and making holes in the floor. Is why I mentioned IB as seen a great result for very minimal outlay and for me in the performance stakes. And especially when you say
That is not a sub this is a sub. Well norpus' falls in that category.

But yeah was only a suggestion and know full well not for everyone, leave you to it ...good luck an sure will be all you want it to be abs more.

Edited by :) al, 22 January 2012 - 05:45 PM.

[kdoot]

Awesome concept. I so wish there were a less bulky way to get 20Hz in my room.

If you do actually build this, please blog it with pictures along the way. Burying under your floor? So cool.

[Drizt]

Awesome concept. I so wish there were a less bulky way to get 20Hz in my room.

If you do actually build this, please blog it with pictures along the way. Burying under your floor? So cool.

My subs with eq are flat to 10hz and i get 110db there no probs. You dont need massive subs as power and brute force can get you there. High sensitivity is not the be all and end all.

[Mika75]

What about Regenerative Transmission Line™

http://www.wisdomaud...om/pdfs/RTL.pdf
http://www.wisdomaud...tasheet_USA.pdf

At frequencies at and near 20 Hz, the trans-ducer is loaded by the tuned pipe, substantially reducing the cone motion and distortion (by a factor of 10) while generating the magnified energy (approximately 9 dB more than the direct output of the driver cone) to the exit of the pipe opening.

[Drizt]

LLT is also a winner.

But paul has chosen his path, good luck with it.

[Paul Spencer]

I actually did the write up on the blog where I mentioned about having the kits already ... forgot that when I started this thread.

A sealed sub will get 20 Hz, it's just inefficient. A vented sub will get to 20 Hz, but it simply extends the efficiency down lower by avoiding earlier roll off. A tapped horn has the extension of the vented box, but increases the efficiency across the entire (yet reduced) bandwidth.

I was looking at a design for Happy Pants with some pro woofers, hoping that the TH would go better as it would have been a fun build. But as it turned out, I couldn't get a better result in the sims than a vented box which could be smaller.

Mika,
That is a tapped horn marketed under a different name.

[Antripodean]

Paul, just to stir you a little bit I would go with a FLH as I understand they have less resonant peaks than a TH. A TH needs more EQ to flatten response. They are very close on efficiency. For example, Lil Mike's F-20 would get to 20Hz and use a pair of 10" drivers. We should do a dual build and see which comes up trumps

[Paul Spencer]

Hi Roger, I'd LOVE to do a FLH, but mouth size is the issue. The opening has to fit between floor joists! This thing only needs to cover 15 - 40 Hz so all that nasty stuff can just be filtered out. In a less constrained situation I'd do a huge built in FLH with bricks! You can get a smooth response and a wider bandwidth. I could probably get one to go into the midrange to cross to the Synergy.

[MichaelWC]

What a great project Paul. I have always been interested in the added sensitivity that can be had by loading a sub in a horn type arrangement. Great match for high sensitive speakers as well. Slightly smaller in size, but the Spud from Danley Sound has always interested me. I will be watching this with great interest. Thanks for sharing.

Cheers,
Michael.

[joz]

Oh well I butt right out your thread then thanks ! Hehe You never mentioned these a done deal had drivers cabinets the lot . All you mentioned was a plan and making holes in the floor. Is why I mentioned IB as seen a great result for very minimal outlay and for me in the performance stakes. And especially when you say
That is not a sub this is a sub. Well norpus' falls in that category.

But yeah was only a suggestion and know full well not for everyone, leave you to it ...good luck an sure will be all you
want it to be abs more.

Al, about IBs not being for everyone.I think you have a point.
Norpus' neighbours don't like them.
In Pauls case i'm sure sound leakage would be less of an issue. Also he has no large box in his room and plenty of extension.

[Paul Spencer]

Well, there is now a plan and it's going ahead on the weekend!



Yes, two bass horns there. F20 and T20!

[henry218]

wow,

paul, i guess u'll make some enemies this weekend

cheers
henry

[Drizt]

Paul, do you have a more detailed plan we can have a look at for the second one? Where is the mouth for instance?

[Paul Spencer]

There isn't much more detail involved here. T20 on the right is shown in plan view with the mouth at the top in between drivers ... whilst F20 can be oriented in a few ways.

The mouth is over the magnets. I'll probably add bracing before the top goes on. The least simple part is the installation, where it has a neck that connects to the floor at an angle. It will be a hole in the floor right in the corner, under the bass traps with my Synergy horns and bass bins flush with the front of the traps.

To give an idea of size, F20 is 1500 x 750 x 500. (562L gross) T20 is 2200 x 600 x 400 (528L gross) ... T20 being more slim has more surface area, uses more material. It has more output due to the drivers, but is less efficient.

[ryzaa]

Hey Paul, its good to finally see some of your goals with horn loaded subs being achieved here.
Once it is completed., I hope you enjoy your increased low frequency extension. Just dont get lost trying to make it as loud down low as you can, the neighbours dont normally enjoy it that much

[Paul Spencer]

I actually get 15 Hz extension already, but there is some EQ cheating and some room gain to get there. With the horns I'll have more headroom.

The woofers that I already have could actually probably annoy the neighbours more. The subs will only go up to 40 Hz, they will probably get lost outdoors, but the woofers run 40 - 250 Hz and they also have more output.

Edited by Paul Spencer, 05 February 2012 - 04:30 PM.

[19hZ]

is this in progress? photos?

[Paul Spencer]

All the timber was cut yesterday ... they are on the blog! I didn't get to start assembling because I was working on 3 other boxes! It's actually not a difficult build and I'll probably have them all done (minus finishing) by the end of next weekend. The tricky part with T20 is the installation, the build is dead easy, especially since I'm not being fussy on looks and precision in terms of angles and fit. Construction adhesive can be a good friend!

[blackfox]

Paul it looks like you have been an extremely busy man since I spoke to you last, I'm looking over the photos of the builds as we speak. looks great!

[Paul Spencer]

Yes very busy! I'm hoping to get my tapped horns installed this weekend. Assembling is quick and easy, installing is where it gets interesting!

[Peter the Greek]

You're going to enjoy these Paul. I am helping a mate build his room at present. He's got two of the Danley DIY kits - thumping, absolutely thumping.

They are the first tapped horns I have heard. I prefer sealed subs, but the bass from these things is extradinary

[Paul Spencer]

Don't ask me why but I've been putting my head inside these bass boxes and making funny noises. I can get them to sound like a foghorn! I'm not surprised with the F20 because it's an undersized horn and can't run up high. Out of all the recent bass projects, only my 60L sealed bass bins will run up high. They will be stuffed full of damping, mass damped internally. Going up to 220 Hz or so.

What do you like better about sealed boxes? Tapped horns are really fussy about their top end, things get ugly so you have to cross them lower, steeper slopes, etc. They have funky things going on if not integrated right.

That looks like a fun setup there!

This is F20, a front loaded horn


with a 12" driver on top for some sense of scale.

What are the mains?

[Peter the Greek]

I cant quite put my finger on it - certainly after the first round of calibration is was much better "tighter". When we pushed them really hard I though I could hear them "chuffing" a bit

I think your two pronged approach will work nicely with your "little" sealed subs doing the higher stuff.

Got any new pics of your room or is it all still work in progress?

[Paul Spencer]

I have a lot to do before I take photos in there

[Paul Spencer]

Well, I've had a chance to fire up F20 and it definitely is a beast. It's actually a front loaded horn, but similar in size. Initial run had it sounding kind of PA like. The bass had that pro sound chunkiness to it, fun for rock music but I know in that state it won't do all. So a couple of measurements and a quick integration and it's no longer so readily recognisable as any particular type of bass. Integration can totally change the character of the bass, very quickly! It wouldn't surprise me if my tapped horns came out similar. Surprisingly the box really doesn't seem like it could benefit from being any more solid. It's light enough that anyone could move it around, despite being huge. There is a sense when playing it that this thing could hit with an almighty big stick!

[mr-happy-pants]

Hit me with rhythm stick
Hit me
Hit me

hiiiiiit me!

[Paul Spencer]

It definitely hits with a rhythm stick!

[Paul Spencer]

Progress today:
http://redspade-audi...pped-horns.html

[gainphile]

Well, I've had a chance to fire up F20 and it definitely is a beast. It's actually a front loaded horn, but similar in size. Initial run had it sounding kind of PA like. The bass had that pro sound chunkiness to it, fun for rock music but I know in that state it won't do all. So a couple of measurements and a quick integration and it's no longer so readily recognisable as any particular type of bass. Integration can totally change the character of the bass, very quickly! It wouldn't surprise me if my tapped horns came out similar. Surprisingly the box really doesn't seem like it could benefit from being any more solid. It's light enough that anyone could move it around, despite being huge. There is a sense when playing it that this thing could hit with an almighty big stick!

Very nice. How do you actually use one of these beasts? My understanding is that the impulse from the woofer will take some times to reach the mouth, hence a delay is required for the rest of the speakers (subject to placement) ??

[Paul Spencer]

There is about 4m of extra path length, but that is easy to compensate for. When you see it, time alignment won't be the first thought!

[joz]

Paul, you have to much free time!

[Paul Spencer]

Joz, every DIYer has to at least build one sub bass horn.

[Paul Spencer]

Now being trialed in the room:



Dual opposed to reduce cabinet vibrations:



Each driver has a removable panel to install the drivers:



I didn't skimp on bracing:



Although I did skimp on looks and neatness (it doesn't matter for an under the floor install). Haven't had time to measure and integrate it properly, or a good listen. I just did a quick run. Well I now have window issues! I knew they rattled around 20 Hz, but it is normally so rarely an issue.

[Drizt]

Pretty damn cool Paul.

[Peter the Greek]

Well I now have window issues!

Its funny how this works. When we calibrated my mates place, his gutters rattled at I think it was 36hz, not 35, not 37, just 36. Didn't rattle at anything down to 10hz

[Paul Spencer]

I have a heater that is even worse. I know from running test tones in the past that the old sash windows rattle around 20 Hz. Nothing a few bit of cardboard won't fix for now until I replace the windows.

The beauty of ply is that this thing is huge, strong and very well braced yet I was able to move it into the house unassisted without it being a test of strength at any point. Not bad considering it's 2.25m long so has to be angled to fit through doorways. I'm glad I didn't make it 2.4m as originally planned!