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Old 15th June 2013, 06:34 PM   #21
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Quote:
Originally Posted by jReave View Post
Here's the idea in graphic terms. We can roughly equate the driver's step response with it's transient response. First up is the Audax HM100 which you are trying to match the woofer to. Then follows the Seas L16RN-SL sealed with Qtc=.707 and then Qtc=1.25. Last is the RN-SL ported in 28L.
All of the above, especially the graphics, help explain a lot - thanks!

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BTW, how many subs do you have?
One right now, a Rythmik F12. I plan to get a second.


Are there other woofers that might be a compromise of the transient response of the seas with the sensitivity of the Audax (also about the same price)?


btw. Where in Canada are you (I'm in Calgary)?
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Old 15th June 2013, 06:55 PM   #22
AllenB is online now AllenB  Australia
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Quote:
Originally Posted by rick240 View Post
So does that mean that if designing for rear wall reinforcement that BSC is actually not a 4db or so sensitivity ramp with lower frequencies higher, but a plateau, with only the ones that wrap to the side needing to be higher?
For the most part all frequencies below this point will wrap. There will be some ripple in the diffraction response and the subsequent reflections will cause comb filtering down to the point where the wall causes clean reinforcement. Within this range you may have issues but there are ways to minimise them.
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Old 15th June 2013, 07:02 PM   #23
jReave is offline jReave  Canada
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Unfortunately, I find myself presently in the greater Toronto area. Uhg. I used to live in Whistler - now that was something special.

The reason I asked about 2 subs is because of LF localization. If you have 2 of them, they can be placed beside your mains (altho with other trade-offs possibly) and then you may xo a little higher than 80Hz without a problem, which would bring the Audax woofers sealed back into the running, for example. But if memory still serves, the Rythmik's don't like to go that high.

What was your goal for box volume for the 2 woofers?
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Old 15th June 2013, 08:33 PM   #24
Jay1111 is offline Jay1111  United States
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While personally I think the whole sealed/ported argument is a little ridiculous. and older then dirt. If you're swayed by it, there are plenty of 6.5" woofers with an acceptable roll off and decent sensitivity.

The Madisound Speaker Store
Click the image to open in full size.

Click the image to open in full size.


A pair in 1 ft3 sealed gets an F3 of 67hz.
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Old 15th June 2013, 09:37 PM   #25
jReave is offline jReave  Canada
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Just stating my preference for sealed and thinking it would be the better choice for this project not only because of the improved transient response but because of size considerations as well.

Jay, that ScanSpeak is a nice affordable driver but I'm wondering if the larger outside diameter (180cm vs 146cm for the Seas) and box volume (for the pair, 28L vs 16L for the Seas) might be unsuitable for the OP's application of a bookshelf 3 way. I'm figuring baffle dimensions and box volume (or WAF in other words) might be a prime consideration and I'm trying to find out that parameter right now before I make any more recommendations.
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Old 16th June 2013, 01:43 PM   #26
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That ScanSpeak looks quite interesting. As I am sure you guys have listened to many more drivers than I have, I have a question: looking at ScanSpeak, for a design where the woofer's role is 80 - 500Hz, what would a Revelator or Illuminator provide over this Discovery (Discovery has obbvious price and sensitivity advantages, and appears to have flatter FR)?

As to size, I had been assuming that with two woofers, a mid and tweeter, along with a front slot port (I had assumed i would need a port, and with against the wall placement it would have to be front ported) that these would be just under 24" tall. And of course, for WAF if they could be closer to 20" would be better (so if sealed works that would eliminate an inch or two).

Jay, the parameters in your show quite a bit lower efficiency for the 8434 than at Madisound - why? Are those Zaph's measurements?
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Old 16th June 2013, 06:12 PM   #27
Jay1111 is offline Jay1111  United States
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Quote:
Originally Posted by rick240 View Post
That ScanSpeak looks quite interesting. As I am sure you guys have listened to many more drivers than I have, I have a question: looking at ScanSpeak, for a design where the woofer's role is 80 - 500Hz, what would a Revelator or Illuminator provide over this Discovery (Discovery has obbvious price and sensitivity advantages, and appears to have flatter FR)?

As to size, I had been assuming that with two woofers, a mid and tweeter, along with a front slot port (I had assumed i would need a port, and with against the wall placement it would have to be front ported) that these would be just under 24" tall. And of course, for WAF if they could be closer to 20" would be better (so if sealed works that would eliminate an inch or two).

Jay, the parameters in your show quite a bit lower efficiency for the 8434 than at Madisound - why? Are those Zaph's measurements?
Those are Zaphs measurements.

Quote:
Also note that the SPL number on the T/S parameters is an efficiency number based on one watt. Additionally, this number is calculated rather than actual. The SPL shown on the response graphs is a sensitivity number based on 2.83 volts and is actual rather than calculated. If you want to "believe" one, the SPL shown on the response graphs would be best to use.
The fiberglass cone SS developed is pretty great, showing an incredibly damped top end. The motor design is much more basic, there is rising distortion in the mid range, but as a woofer that wont be an issue. The higher end SS's have lower overall distortion, more xmax, and usually stronger motors.

Last edited by Jay1111; 16th June 2013 at 06:14 PM.
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Old 16th June 2013, 08:58 PM   #28
jReave is offline jReave  Canada
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Rick, I'm going to apologize in advance because I think I'm going to muddy the waters a bit for you here.

First let me say that I like your choice of the Audax and Seas for your purposes. The way you want to use them makes good use of their strengths. Again, I'd probably look at a different tweeter though.

If you went with internal dimensions of something like 7x20x11 inches, you get about 25L to play with. You need about 16L sealed for the 2 Seas, maybe 2L for the Audax and now you have 7L left over for bracing, driver volumes, xo's, internal mid chamber walls, wall damping etc. So something like that should easily work nicely especially with the xo's being handled by a professional.

However, I haven't heard them myself. I know theyre good but I dont know exactly how good. Tony Gee likes the Seas in this monitor http://www.humblehomemadehifi.com/do...nitor_copy.pdf, and Linkwitz uses it in his PLUTO-2.1 omni-directional loudspeaker. What I do know is what I use the Revelators in Zaph|Audio - ZD5 - Scan Speak 15W8530K00 and Vifa XT25. Im running them sealed in the best cabinet I could build, crossed to a sub at 80 Hz and they are jaw droppingly good - detail, dynamics, imaging, instruments and voices emerging out of an inky dark, soundless background.

Now, let's stop for a second and do some accounting.

Using current prices at Solen:
Audax = $93
Seas = 2 x $99 = $198
And Im going to add in a guestimate of the extra xo for a 3-way = $50
So youre looking at around $340 to cover between about 80 to 2500 Hz.

Now here are a few of the big boys that you can get for the same kind of money that will cover the same range.
https://www.solen.ca/pdf/scan/18w8531g00.pdf - $228
https://www.solen.ca/pdf/sb/Satori/mw16p.pdf - $284
The Madisound Speaker Store - $320 (from the States tho and will probably need more work in the xo to kill the HF resonance)

All of those will go below 80 Hz sealed in volumes that will work for you. You'll only need 1 and use it in a 2-way, but believe me, that will be more than adequate.

You should take a serious look at the Kairos using the Satori by a very well respected designer - http://meniscusaudio.com/images/The%...ff%20Bagby.pdf. Yes I know it's ported, but you could just as easily change that to a sealed allignment.

Not that I think that distortion measurements tell the whole story, but they are a good starting point. Below are the graphs for the Seas L16RN-SL again, then the Scan Discovery again, then the Revelator 18W8531G00, followed by the Satori and then the Scan 18WU4741T (the 4 ohm version). Look in particular at the 3rd harmonic in the usable frequency range. The winner is number 4.
Attached Images
File Type: gif Seas-L16RN-SL-HD.gif (20.1 KB, 71 views)
File Type: gif Scan-Speak-18W8434G00-HD.gif (21.8 KB, 71 views)
File Type: gif 18W8531G-HD.gif (22.8 KB, 71 views)
File Type: gif Satori-MW165DC-08N36-DA00-HD.gif (24.3 KB, 12 views)
File Type: gif Scanspeak-18WU4747T00-HD.gif (23.0 KB, 13 views)
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Old 17th June 2013, 12:21 AM   #29
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I hope people won't mind if I approach this differently. On the technical details and components you seem to be getting good advice. But I think as much as we need to consider the technical aspects and components, we need to treat this as if you were going to a HiFi shop and buying speakers. You still need to make the same consideration.

When advising people on buying audio equipment is

- Budget
- Circumstances
- Goals

Under Goals would be preferences and priorities. Can't get what you want until you know what you want.

So, start with Budget, because that really defines the entire project.

Next, Circumstances, in what size room and for what type of music will the system be used? Further how do you listen - loud, modest, etc..? What type of music do you listen to - Rap/Dubstep/Techno/Club - have very different requirements than Jazz or Classical.

What are your priorities? That is, how big can the speakers be? Do you stress bass weight over clarity, or would you sacrifice a degree of bass weight if it brought you absolute clarity?

Tied in with this are preferences, they are similar, but not quite the same. Myself I prefer Floorstanding/Tower speakers, that's just the way it is. I prefer large drivers, though in today's market, 10", 12", and 15" bass drivers are all but gone. But it is still what I prefer.

Approaching a project in this fashion informs the design. It informs the choice of drivers. It informs the cabinet design.

In your original design, you were, based on the information I found, you are looking at 5" bass drivers and 4" midrange drivers? I'm not sure if that creates a balanced system. Though certainly it can be made to work.

Next, consider the cabinet. Starting with a 5" or 6.5" woofer, if we want the cabinets somewhat proportional, can you squeeze an additional 4" speaker on the front face and still maintain reasonable proportions of dimensions?

Next, why a 3-way? Personally I prefer 3-way because it make driver selection easier. With a midrange you can limit each driver to its optimal range. But the design is slightly more dicey.

Next, the drivers have to be relevant to the design goals. The drivers for a 3-way Low-Bass, Mid-Bas, Tweeter system are much different than Woofer, Mid-Range, Tweeter, which in turn are different than a Woofer, Tweeter, Super-Tweeter design.

Any decision is the right decision if it meets the design objectives. In your case you seem to be looking at a Woofer, Mid-Range, Tweeter configuration.

So, we start there. Assuming you can come up with workable cabinet dimensions, you are probably better off with a 3" Cone Midrange or a 2" dome Midrange.

Though not etched in stone, using the Golden Ration (1.618), each progressively longer cabinet side should be 1.62 larger than the previous.

So, if we assume a 6.5" bass driver, we need a cabinet of about 8" wide. So, 8" x 1.62 = 9.62" Deep, 9.62" x 1.62 = 15.58" High. Again, not etched in stone, but it sets a starting point.

So, dimensions (ball park) 8" x 9.62" x 15.58".

Is that enough room for a 3" or 4" Mid-Range driver combined with a 6.5" bass driver. Do keep in mind it is possible to get very good yet very small tweeters. Here is an example -

Dayton Audio ND16FA-6 5/8" Neodymium Dome Tweeter 275-025

Vifa BC25SC55-04 1" Square Frame Tweeter 264-1024

Dayton Audio ND20FB-4 Rear-Mount 3/4" Neodymium Dome Tweeter 275-035

There are still small but more expensive higher quality tweeters available. This just illustrates the point.

What I'm getting at is that you need to work out the design in concept weighing all the factors of price, goals, circumstances, etc...

Then you need to examine the mechanical realities. To use an extreme example, you can't want a 10" bass driver and still demand a tiny cabinet. The physical reality has to match the conceptual reality.

Then once you have the concept, you start searching for drivers that serve both the budget and the design concept combined with the physical realities.

One additional think to consider for Bass Reflex (ported) cabinets is - do you actually have room for it? Likely with a 3-way, the port is going to need to be on the back. The Port Diameter and the Port Depth will depend on the size of the cabinet and the frequency you want it to resonate at.

As an example, take a Dayton Classic 6.5" bass driver -

Dayton Audio DC160-8 6-1/2" Classic Woofer 295-305

It has an (fs) resonance frequency of about 34hz. That is roughly the range where you would want the cabinet to resonate, and that pretty much reflects the lowest frequency the speaker is capable of.

Take the cabinet dimension I gave you, which are internal dimensions. Then subtract an estimate of the Woofer volume (space) from the cabinet volume. Now use that volume to determine the diameter and depth of the port necessary to make that size cabinet resonate at the desired frequency.

You have about a 0.75 ft cabinet. We will subtract .015 Ft for the volume displaced by the woofer. That leaves 0.6 ft.

Using this port calculator -

LinearTeam

Let's see what the possibilities are -


A single 3" diameter port tuned to 36hz would need to be 22 inches long.

A single 2" diameter port tuned to 36hz would need to be a modest 9.4 inches long.

A single 2" port tuned to 45hz would need to be 5.5 inches long.

One additional consideration, the Vas specification of the Dayton speakers is 0.87 ft. For what it is worth.

Things to consider.

LinearTeam

Before you start choosing drivers, you need to take all these things into consideration.

First, treat it like you are buying a speaker and consider everything you would consider when doing that.

Next, work out the physical realities with potential drivers you are considering.

Next, work out the crossover frequencies relative to the drivers you have pick and that are consistent with the design concept.

I don't know if this is any help, and you are free to accept it or reject it as you see fit. But do give it some consideration.

For what it is worth.

Steve

Last edited by BlueWizard; 17th June 2013 at 12:36 AM.
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Old 17th June 2013, 12:31 AM   #30
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Originally Posted by jReave View Post
Rick, I'm going to apologize in advance because I think I'm going to muddy the waters a bit for you here.
I came here asking for thoughts and opinions of those who klnow more than me - I appreciate all of them.

The reasoning for a 3-way is that I want the centre speaker to be a W-T/M-W instead of an M-T-M for both midrange clarity and reduced comb filtering issues.

So to get perfect timbre match across the front, that means the L/R mains are also 3-way, with the same drivers.

That's my thinking - as flawed as it may be

I'll look into the other suggestions more too.

Thanks for all feedback and suggestions.
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