| Nuuk |
As you may have seen, I now have my Goodmans 201's in their new open baffles so I am turning my attention to the bottom end.
The plan was to get four 12 inch drivers and use them in a W baffle with an amp each and some EQ. Thinking about it again though, this seems an expensive way (for me anyway) to get bass from around 65Hz down to 40Hz (the realistic limit for this configuration according to SL).
An alternative is to go with a single driver on each channel a la NAO This means half the number of drivers and amps, leaving funds for a possible sub to get down even lower.
I think that my chosen driver, the Alpine SWE1250 would work in either system.
Or, how much quality would I loose by building an ELF system (perhaps one per side) to go up high enough to 'meet' the 201's at around 65Hz?
Does anybody have any comments on this issue to help me make a decision? |
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| Guss |
You don't need to reach fully 65hz because the rolloff of your speakers together with your sub will complete the spectrum...at a certain point...
The elf seems to emphasis the lowest end which you barely would hear and most of the records still miss that part exept maybe for techno and/or rap... Even if the thing is tweakable (he used the amp I think to get that response so far ) you should consider a something tuned say at 30hz where you can enjoy the 40-50 region...There is a lot of diy sub projects on the net actually, try seatching for what you want exactly, maybe there is one for you out there. |
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| Mats J |
I can't seem to find anything on the Alpine SWE1250. the closest I found was swe1241. Could you provide a link or something?
Thanks,
Mats |
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| kelticwizard |
Nuuk:
Is there any good reason a ported, sealed, or Transmission Line enclosure cannot meet your needs?
Mats:
Here is the link to Alpine USA. I clicked "Products" and the thing took so long to load, (I use dialup), that I said the heck to with it.
If Nuuk or anyone has the Thiele-Small specs for the Alpine SWE 1250, please post. :) |
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| Nuuk |
I wanted to avoid a boxed sub if possible and use dipole as people rave about the better quality of the dipole, and it should be less of a problem in my room which is 4 by 3 metres (12 feet by 14) And of course, the main system is dipole.
It seems that Alpine driver is the SWE1241 (not sure how I got 1250 :confused: ) and here are the specs as it does take a while to get them off the site.
Alpine SWE 1241
Thiel Small Parameters
Coil Height (Hvc) : 33.4mm
Cone Area (Sd) : 490.87 sq. cm
D.C.Coil Resistance (Re) : 3.6 ohm
Electrical Q (Qes) : 0.70
Equivalent Suspension Stiffness (Vas) : 61 liters(2.3cu.ft.)
Free Air Resonance (Fs) : 31Hz
Frequency Response : 26Hz - 1kHz
Gap Height (Hag) : 10mm
Impedance (Nominal) : 4 ohm
Inductance (Le) : 2.78mH at 1kHz (0.86mH at 20kHz)
Linear Excursion (X linear) : 11.7mm
Maximum Excursion (X peak) : 23.4mm
Mechanical Excursion (Peak-to-Peak) : 40mm
Mechanical Q (Qms) : 9.68
Sensitivity : 89 dB/W/M
Total Loudspeaker Q (Qts) : 0.66
Features:
Woofer
Bumped Backplate
Custom High-Strength Steel Basket
Designed and Engineered in the USA
Dual Progressive Nomex® Spiders with Integrated Tinsel Leads with Edge Control
High Excursion 3/4" Santoprene Surround
High Strength Brass Voice Coil Bobbin
Kevlar Reinforced Pulp Cone
Oversized Parabolic Dustcap
Specs:
General-Subwoofers
Diaphragm Material : Kevlar Reinforced Pulp
Magnetic Weight : 64oz.
Mounting Depth (top mount) : 159mm (6.4”)
Mounting Diameter (top mount) : 274mm (11”)
Recommended Box Types : Sealed/Bandpass
Recommended Sealed Box Volume : 0.8 – 1.7 cu. ft.
Spider Material : Dual Oversized Nomex
Voice Coil Diameter : 38mm
Power Handling
Power Handling Capacity (Peak) : 600W
Power Handling Capacity (RMS) : 200W |
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| Nuuk |
| quote: | | You don't need to reach fully 65hz because the rolloff of your speakers together with your sub will complete the spectrum...at a certain point... |
That's right Guss. I think that Rod Elliot suggests going to about 0.75 of the -3db point of the main drivers. |
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| kelticwizard |
Nuuk:
Well, as you pointed out, really deep bass is hard to get from a dipole.
At any rate, all that is required is to take a board, a stand that allows the board to tilt back for the board to keep it's balance, and see how it sounds.
With an Fs of 31 and a Qts of .7, your speaker in a true Infinite Baffle, (where the box affects the speaker not at all) would be -3 dB at 31 Hz, which is very good.
You don't have any closet doors handy to mount these in, do you? That would save a lot of trouble. :)
Otherwise, what I would do is to take a closed box of 2.3 cu Ft or larger. The sealed system in the closed 2.3 cu Ft box will remain at the midpoint all the way down to 42 Hz, with a respectable Qtc of 1.0. If you want, you can make an aperiodic vent and lower the Qtc even further.
Try the experimental slanted board first-easy enough to do, I would think. ;)
Kuei did his in acrylic, but the principle remains-one slanted board to a single base board.
http://www.diyaudio.com/forums/atta...p?postid=234863 |
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| Nuuk |
| quote: | | Kuei did his in acrylic, but the principle remains-one slanted board to a single base board. |
That's Kuei's full-range unit, not his bass woofer!
I'm leaning toward the U baffles but in my case they would be firing through the main baffles and I wonder what effects this may have on performance?
http://nickw.worldonline.co.uk/etc/gob&woofer.jpg |
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| Timn8ter |
| Does anyone have one of these? |
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| Nuuk |
| quote: | | Does anyone have one of these? |
Aaarrgh, not another option :bawling:
Well it looks good on paper but.......
And of course, for those of us outside the US, it would be a case of finding suitable drivers. I think for now, I would rather keep things a bit simpler but it would be good to find out more from somebody who has actually heard one. |
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| Nuuk |
To move this topic on a bit, can we assume that I will use the U baffle configuration with say the Alpine SWE1241 driver.
Now what about crossover and EQ? I assume that that an active crossover would be best between the 201's and the 1241's but is their an ideal type?
I have a circuit which was used to EQ the bass section of an active three-way speaker but the bass section was two drivers in a sealed box so I doubt it will be useful for the U baffle. The slope of that closed box was exactly 12db/octave but what would it be with the U baffle? |
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| qi |
dipole is the latest fad.
It does not go low.
Use a sonotube, dude... |
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| Nuuk |
| quote: | | dipole is the latest fad |
Thank you for this valuable information. ;)
| quote: | | It does not go low. |
I am building some woofers not a sub! :smash:
| quote: | | Use a sonotube, dude... |
Not for this application. :whazzat: |
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| qi |
Actually I really like your orignal idea (ELF aka EAS).
I have two 18" CTS subs in 3' x 3' x 3' enclosures just waiting to be EAS'd.
You start and I will follow your lead... :) |
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| sfdoddsy |
I'm all in favor of dipole bass, but I may be misunderstanding what you are trying to do. Is it to extend the bass response of you speakers down to 40Hz, or to get really good deep bass response?
If it is the former, I can't really see the point of the added complication of going dipole. If the latter, go dipole but use drivers that will make a difference. You need xmax for dipole bass whther you use high Q or active EQ.
A Stryke AV15 a side would be my suggestion.
However, given the room size, your resonance thingie would be about where you are planning to cross over, so you may as well just go for sealed monopoles.
Cheers
Steve |
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| Nuuk |
| quote: | | Actually I really like your orignal idea (ELF aka EAS). |
| quote: | | However, given the room size, your resonance thingie would be about where you are planning to cross over, so you may as well just go for sealed monopoles. |
Well, I was just looking to extend the bass response but if the main panels go down to around 65Hz, maybe it's better to go for the EAS (ELF) system and go all the way down to sub levels. I guess dipole bass quality is more important when going up into the 200-300Hz frequencies.
These are the T/S specs for the SWE 1241:
Thiel Small Parameters
Coil Height (Hvc) : 33.4mm
Cone Area (Sd) : 490.87 sq. cm
D.C.Coil Resistance (Re) : 3.6 ohm
Electrical Q (Qes) : 0.70
Equivalent Suspension Stiffness (Vas) : 61 liters(2.3cu.ft.)
Free Air Resonance (Fs) : 31Hz
Frequency Response : 26Hz - 1kHz
Gap Height (Hag) : 10mm
Impedance (Nominal) : 4 ohm
Inductance (Le) : 2.78mH at 1kHz (0.86mH at 20kHz)
Linear Excursion (X linear) : 11.7mm
Maximum Excursion (X peak) : 23.4mm
Mechanical Excursion (Peak-to-Peak) : 40mm
Mechanical Q (Qms) : 9.68
Sensitivity : 89 dB/W/M
Total Loudspeaker Q (Qts) : 0.66
Of course, if I go for the EAS selaed boxes, I presume that removes the necessisty for a highish Qts or is that still a requirement?
Using one per side, I think 12 inch units would suffice and be much more easy to accomodate. Rod Elliot reported very good results with a single 12 inch driver in EAS mode.
The other advantage with the ELF is no crossover.
| quote: | | I have two 18" CTS subs in 3' x 3' x 3' enclosures just waiting to be EAS'd. |
Qi, as I understand it you have to size the enclosure so that the subs roll of at the correct frequency to compliment the output from your main speakers so you may be looking at rebuilding those cabinets.
I'm back off to ESP for yet another thorough read.......:h_ache: |
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| qi |
Nuuk:
I think if I run (as-is) that 20 Hz test and it passes (no 60 Hz harmonics, no sound at 20 Hz -- but cone movement) I then can proceed down the EAS path.
Otherwise, I will remove the driver, attach it to a 1 1/2" x 24" x 24" plywood mounting panel and place a 72' x 12" fully stuffed sonotube on top (routing the panel to fit the sonotube). This seems like a cheaper, easier (albeit less elegant) way to go (google: "el-pipo" for details) than building new enclosures.
I wonder how my better-half will react to missile silos in the family room... :D |
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| Nuuk |
Well, I don't have a better half but neither do I have room for those industrial chimneys in my living room so I know what my preference is there ;)
That's one appeal of the EAS system, it's very compact for a sub that goes as low as it does.
What is the general opinion about having a single sub and having a pair (on for either channel).
I have just measured the new baffles and they are fine down to 74Hz before they drop away. Would I be able to tell between a single sub and a pair of them at 74Hz? |
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| qi |
A single sub can used if placed VERY CAREFULLY and OPTIMALLY.
If you can, go with two (google: "PERFECTIONIST AUDIO").
"bass is non-directional" (boy, do I have a bridge for you) |
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| BAM |
I have my Stryke AV12 driver now. It is a fabulous part. Everything about it says "craftsmanship". My hat is off to the folks at TC sounds for producing such quality drivers. You may want a HE15 for an URPS (Under Resonance Principle Subwoofer -- like the ELF/EAS) becasue they eat driver excursion for lunch. Also, contact Stryke's proprietor, John Janowitz, and see how much power you can safely power a HE15 with, and get a pro amp that can supply that, because you will need all of it. A HE15 should be cheaper than an Adire Tumult. It has slightly less excursion, but it will be potent enough to handle everything you throw at it.
In addition, make sure that your box is built of double-layered 3/4" MDF and add at least two internal shelf braces. think about making it strong enough that an elephant could tap-dance on top. With all that power being fed to the driver, the enclosure needs to be unshakable. It will weigh a ton, but for a subwoofer that's a very GOOd thing. |
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| BAM |
| I've killed this thread... |
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| Nuuk |
| quote: | | I've killed this thread... |
I hope not :bigeyes:
I did some more research last night and notice that Joe Rasmussen is another who prefers two subs to one. He states that if using one, it must be placed exactly between the two main speakers which in my room would not be practical. So it looks like whatever I build will have to be a two box affair.
I have aways been of the opinion if the main speakers go down to about 40Hz, you can get away with a single sub. Above that no. |
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| richie00boy |
If you want a demo of a single sub setup, you are welcome to come over to my place and have a listen. My room is 12 x 17 so not too unlike yours. I have my sub slightly to one side and it's fine. In fact it's so good I'm thinking of not bothering with a dipole sub now. I think it's crossed over at 80Hz, but I need to check that with a test tone sweep. However, my mains go down to at least 50 Hz.
The sub is a cheap affair using a £30 12 incher from BK Electronics, one of their 100W MOSFET amps and a Linkwitz Transform. It's plenty loud enough for music, but just almost runs out of steam with films at my desired listening level. |
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| Nuuk |
| quote: | | However, my mains go down to at least 50 Hz. |
I think that is why you find that one sub works but I certainly wouldn't mind a listen. Where exactly are you? |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Nuuk
Well, I was just looking to extend the bass response but if the main panels go down to around 65Hz, maybe it's better to go for the EAS (ELF) system and go all the way down to sub levels. I guess dipole bass quality is more important when going up into the 200-300Hz frequencies.
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It certainly works fine for me.
| quote: | Originally posted by Nuuk
Of course, if I go for the EAS selaed boxes, I presume that removes the necessisty for a highish Qts or is that still a requirement?
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No, for ELF the requirement is a Driver with a Qt & Fs that is comparably low, so that when build into the box the Qt is 0.7 and the Fs about the same as the speaker it is meant to match. Of you can use the Linkwitz "poles & zeros" EQ and a normal (adjustable) lowpass filter.
| quote: | Originally posted by Nuuk
Using one per side, I think 12 inch units would suffice and be much more easy to accomodate. |
Yup. A pair of 12" in one appx. 16" cube woofer works fine here.
Sayonara |
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| richie00boy |
| Warminster - half way between Salisbury and Bath. I think it's probably about an hour for you, maybe slightly more? |
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| Nuuk |
And to you Mr KYW - I thought that you would never get here ;)
Thanks for the clarification on the EAS driver requirements and your experience with open baffles+subs.
Are you using EAS/ELF or are your subs just sealed box types with crossovers? |
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| BAM |
You know how Bose Acoustimass modules put out a ton of midbass? Well, when I got a set of Cambridge Soundworks Ensemble IVs for my parents' house, I found that the little bass module also was putting out more than its share of midbass. On the Bose web site, they say that the best placement for an Acoustimass module so as to not screw up the image as badly is to put it along the front wall, with the port firing along the wall. Perhaps with a single subwoofer, you could also do this. I tried it with the little Ensemble bass module and it really helped the midbass to seem to come from the little speakers. (dangerous words...)
I still like my dual AV8-TL's idea. But if you've got the time and money, I would say do dual EAS/ELF/LT subwoofers. Make sure you are using powerful, high-excursion drivers, though. |
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| Nuuk |
| quote: | | Warminster - half way between Salisbury and Bath. I think it's probably about an hour for you, maybe slightly more? |
Ah - UFO country eh? At least it used to be! :apathic:
Yes, it is about an hour, or used to be before some idiot came up with the idea of 20mph speed limits in every village along the way. Soon it will be quicker to go by stage coach!
Well, I'll have to think about borrowing a car and get back to you on that one but the above post has swung me toward two of whatever I decide to go for. |
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| Nuuk |
| quote: | | put it along the front wall, with the port firing along the wall. |
Thanks BAM (your post appeared while I was replying to Richie).
That is not really an option for me in my listening room.
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| richie00boy |
| quote: | | Ah - UFO country eh? At least it used to be! |
That is sooo spooky! I've only been living there about 18 months and knew nothing of the UFOs. Then only this morning on the way in to work I found out! And now you mentioned it too!
Good luck with your sub project. As I said, mine only just runs out on films so am looking to build something new that doesn't break the bank. I may go with a 15 incher and try to make it into a table or something, or possibly use the two 12 inchers I have now (only 1 in use though) and build 2 smaller units.
As KYW said, dipole-suited T/S specs are not really that great for a boxed sub. I will add to that that you should not place the sub closer to you than half the distance of your mains - otherwise you can tell where the sound comes from. That was in a different house though, I suppose I should try again in this house and see... |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Nuuk
Are you using EAS/ELF or are your subs just sealed box types with crossovers? |
I use Equalised with passive Poles/Zero PLUS adjustable EQ (0...+6db @ 20...40Hz) and a 3rd order adjustable LPF, using the Thomessen Module from Germany.
So it is not EAS/ELF but a mixture.
If I where to build my own Amp and build the Sub for a Specific system I'd probably measure my Speakers in room (-6db point is required, not -3db) and then select box and driver to give a matching Sub using EAS (dual integrator).
I have attached a little Excel (97 or above) Spreadsheet that calculates EAS systems based on the integrator being Rin = 10kOhm; Rfb = 470kOhm; Cfb = 100nF. I have included two pieces of "best guess fudge" for the responses of the open baffled Supravox and Axiom plus some subs.... I tried to attch the zipped up file - it's too large. Hence if you want the file, e-mail me at work (strictly Nuuk only, all others will be ignored).
Sayonara |
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| Nuuk |
| Thanks KYW, I have (hopefully) sent an email to your work address. |
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| Nuuk |
| quote: | | I will add to that that you should not place the sub closer to you than half the distance of your mains - otherwise you can tell where the sound comes from. |
Thanks again Richie. I hope to fire the woofers through the main baffles so that the subs are somewhat concealed. With the width of the baffles, there is no option to place them to the side of the main baffles.
I had thought of building the sub boxes onto the back of the main baffles but guess that would add vibrations that may affect the main driver. So I am thinking of placing a separate sub box imediately behind the baffles, possibly 'connected' with something that won't transfer all the vibrations. :smash: |
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| Nuuk |
| KYW, I just had my email returned as undeliverable, recipient not known. The address I used was your nhs one! |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Nuuk
KYW, I just had my email returned as undeliverable, recipient not known. The address I used was your nhs one! |
Probably the old one. I have changed my job since, though still NHS. E-Mail me through this site and I'll send on tuesday or the "bare" version without the data I prepared earlier from home....
Ciao T |
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