Hello all,
I've been given two of these woofer, almost for free:
KT 100 V - 4 Ohm | Visaton
Since I have them, I was thinking to build a small subwoofer to be added to my HiFi system.
The idea was to build a small cabinet that could fit under a furniture, so it will be practically invisible.
To increase the perfromance and even reduce the size, I'm contemplating the idea to mount the two woofers in an isobaric configuration:
Isobaric Subwoofer Design — VUE Audiotechnik
I do prefer the vented cone to cone solution.
So, I simulated the thing with WinISD, and it seems to be flat down to 30Hz, with a cut-out frequency (at -3dB) of about 26 Hz.
Mounted in a 11 Liters vented box.
The simulation seems interesting.
Before to start the construction, however, I'd like to hear from you what do you think about this idea.
Anyone here with real experience with these drivers?
What do you think about the idea to having two small drivers in isobaric configuration?
Could someone simulate the configuration (on the maker site you can find the relevant driver Thiele-Small parameters)?
Any suggestion, doubt, idea?
Do you think is it worth to build such a subwoofer?
Thank you in advance.
I've been given two of these woofer, almost for free:
KT 100 V - 4 Ohm | Visaton
Since I have them, I was thinking to build a small subwoofer to be added to my HiFi system.
The idea was to build a small cabinet that could fit under a furniture, so it will be practically invisible.
To increase the perfromance and even reduce the size, I'm contemplating the idea to mount the two woofers in an isobaric configuration:
Isobaric Subwoofer Design — VUE Audiotechnik
I do prefer the vented cone to cone solution.
So, I simulated the thing with WinISD, and it seems to be flat down to 30Hz, with a cut-out frequency (at -3dB) of about 26 Hz.
Mounted in a 11 Liters vented box.
The simulation seems interesting.
Before to start the construction, however, I'd like to hear from you what do you think about this idea.
Anyone here with real experience with these drivers?
What do you think about the idea to having two small drivers in isobaric configuration?
Could someone simulate the configuration (on the maker site you can find the relevant driver Thiele-Small parameters)?
Any suggestion, doubt, idea?
Do you think is it worth to build such a subwoofer?
Thank you in advance.
Attachments
Its never a waste of time if you learn something.
Even if the result is not perfect.
While ago friend gave me sony ht full set. Five little plasticky crappy shiny boxes with subwoofer. I did not throw the thing out, but evaluated. Small boxes had only one little fullrange, while not bad, not good either. Since I had many of them, I added tweeters and made mtm, just a stereo pair.
Subwoofer had just one woofer, not too big, likely ~5", its rubber surround felt very hard, it had almost solid cone, flat dust cap, but it made surprising amount of bass. I used it under the desk in my office, till I gave it to a friend. I was shocked to hear it in his living room, placed in corner, reinforced by walls, it handled quite well. He had nothing before, just tiny built in speakers in the flat screen tv, so you can imagine he was a happy camper. I gave him 2.1 chip based amplifier, with built in active crossover and separate volume for sub, so he could set the sound to his liking. I built better bookshelfs for him later, he is very happy with the sound.
After that experience, I would not discard small woofer. For quiet listening in the office, hiding under the desk, it may be just fine.
Cheers!
Even if the result is not perfect.
While ago friend gave me sony ht full set. Five little plasticky crappy shiny boxes with subwoofer. I did not throw the thing out, but evaluated. Small boxes had only one little fullrange, while not bad, not good either. Since I had many of them, I added tweeters and made mtm, just a stereo pair.
Subwoofer had just one woofer, not too big, likely ~5", its rubber surround felt very hard, it had almost solid cone, flat dust cap, but it made surprising amount of bass. I used it under the desk in my office, till I gave it to a friend. I was shocked to hear it in his living room, placed in corner, reinforced by walls, it handled quite well. He had nothing before, just tiny built in speakers in the flat screen tv, so you can imagine he was a happy camper. I gave him 2.1 chip based amplifier, with built in active crossover and separate volume for sub, so he could set the sound to his liking. I built better bookshelfs for him later, he is very happy with the sound.
After that experience, I would not discard small woofer. For quiet listening in the office, hiding under the desk, it may be just fine.
Cheers!
"Meaningful SPL" and "a lot of air" are relative terms.
A 1" dome tweeter can reproduce 1Hz, quietly. There are lots of people that are content with the speakers built into their TV, with diaphragms measuring 1"x2", and likely with less than 1mm of Xmax.
A couple of 4" woofers will be a useful step up from that sort of thing, but they'll never keep up with a couple of 18"s in sheer output. They're different products for different uses.
FWIW, I'm using a pair of 4" coaxials in sealed boxes and getting flat down to 35Hz with some EQ. It's a desktop system, so outright SPL isn't a concern.
Chris
For your stated use your subwoofer will not be man enough for the job. According to the data sheet you have a driver with a SPL of 80dB (-10dB @ 30Hz). It's a 25w driver. Somebody else can do the math but I'm guessing the maximum SPL of the driver at sub frequencies is around 87dB. (90dB for both drivers being driven by an amp capable of 2 ohms. Or a stereo 4 ohm amp.
You state the you're trying to augment your existing hi-fi. A pair of bookshelf speakers are likely to produce a 1 watt output of over 90dB. For your sub to create a flat bass extension it will need to be cranked up to full power when your main speakers output is 1 watt each.
The sensitivity rating of your drivers is the lowest I've seen. The are many 4" drivers that will achieve the same volume using only 25% of the power.
You state the you're trying to augment your existing hi-fi. A pair of bookshelf speakers are likely to produce a 1 watt output of over 90dB. For your sub to create a flat bass extension it will need to be cranked up to full power when your main speakers output is 1 watt each.
The sensitivity rating of your drivers is the lowest I've seen. The are many 4" drivers that will achieve the same volume using only 25% of the power.
Surtsey,
The datasheet sensitivity number doesn't really apply here: we're operating in the Thiele-Small region, where the cabinet + driver combination will determine the sensitivity.
I threw together a quick 4th order bandpass using Hornresp. It's not a small box, at 33L internal. It does, however, manage 84dB at 2.83v with the drivers in series. ie, 1w into the 8ohm (nominal) load. The bandwidth is approx 40Hz-90Hz.
Pushed against a wall or into a corner, the SPL would increase dramatically, and might turn it into a useful little subwoofer.
Rear chamber = 24L
Front chamber = 7L
Port = 44cm^2 area, 46cm long.
There are certainly better drivers in the world, but these aren't entirely useless.
Chris
The datasheet sensitivity number doesn't really apply here: we're operating in the Thiele-Small region, where the cabinet + driver combination will determine the sensitivity.
I threw together a quick 4th order bandpass using Hornresp. It's not a small box, at 33L internal. It does, however, manage 84dB at 2.83v with the drivers in series. ie, 1w into the 8ohm (nominal) load. The bandwidth is approx 40Hz-90Hz.
Pushed against a wall or into a corner, the SPL would increase dramatically, and might turn it into a useful little subwoofer.
Rear chamber = 24L
Front chamber = 7L
Port = 44cm^2 area, 46cm long.
There are certainly better drivers in the world, but these aren't entirely useless.
Chris
Agreed. It's a big box for a couple of small drivers, and a good 8-10" driver would have a huge performance advantage. Even the cheap MCM long-excursion woofer (55-2421) in a sealed box would demolish the 4th order bandpass I posted on the previous page.
Trying to make the most out of a given driver/cabinet/volume/whatever keeps the tools sharp, though, so I'm happy to have a go when time permits.
Chris
Trying to make the most out of a given driver/cabinet/volume/whatever keeps the tools sharp, though, so I'm happy to have a go when time permits.
Chris
Wel, i don't agree, you can get a satisfying bass out of smaller drivers. I do it with a 6" fullrange in a big MLTL, and get a good bass out of it to about 32Hz F3 in a room of 3.5x6x2.5m. But that driver, the Mark Audio CHN110, has decent xmax (8mm) and BL (5.82), and i use a huge cabinet that emphase the bass (see pic of the cabinet, still in prototype phase).
That Visaton does not have the xmax or BL to do that, and a 4" cone is very small, so very hard to impossible to get loud bass out of it. Even in an TL type of cabinet it won't give loud bass. And it's true that a bigger cone can do it easier. But you can get a decent bass out of the right small cone in the right cabinet.
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You seen to have a weird obsession with Xmax to the point you exclude all other options. I can't only guess the volume of your enclosure but I surmise that I can rotate your design by 90 degrees, install two, bargain basement 10" drivers and surpass your 32Hz output by 10dB.
Contrary to the popular mantra, "Watts are cheap" - they are not. Your system would require 10x the power to produce the same amount of bass - not cheap.
Contrary to the popular mantra, "Watts are cheap" - they are not. Your system would require 10x the power to produce the same amount of bass - not cheap.
I go by specs, not by guessing. And yes, 10" woofers will give more bass than a 6" fullrange driver. Especially 2. How much bass is determinded by how much air you can move, and a bigger cone (10" vs 6") moves more air than a smaller one with the same xmax. So when you want to use very small cone drivers, you need more xmax to give the same bass. And BL is important to show the motor strength to move the cone. What i wanted to say is a 4" cone with little xmax won't give loud bass. Silent is possible if you force it, but loud will never happen. Just like the volume of my 6" fullrange is limited if you tune it that low.
And tha cabinet is big because it's a MLTL, in a reflex i can't tune it that low, but even a bit higher the box will be much smaller. But the group delay will be longer and so the sound more smeared (i'm picky now). If that is no issue for you (and for most it isn't), then use a reflex, and don't bother the complex calculations for an MLTL or the big size. But for that matters...