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Multi-Way Conventional loudspeakers with crossovers

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Old 9th January 2013, 07:01 PM   #41
Siggma is offline Siggma  United States
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Quote:
Originally Posted by tuxedocivic View Post
DrNick - RE Post 31.
That looks great. Nice cross over point.
Yea, right on target. Slopes are right where I want them, for the most part.
Quote:
Good driver integration. Very flat response.
Not really, the woofer has a 2 db hump where it begins to roll that needs to be ironed out. Probably needs a little more inductor and a little less cap or just more inductor. Probably going up to 1.5 or 1.7 on the inductor and maybe a little adjustment on the cap will take care of it. The slope is too steep though, I don't know why I was modeling an LR4 on the woof.
Quote:
Relatively simple cross over.
Yea, it's actually very simple. I have an LR4 slope on both drivers with only 4 components. I think I'll need to reduce the woofer slope to get the phase where I ultimately want it. Symmetric crossovers never work on a flat baffle. They often work with LR4 on tweet and Butterworth second or Butterworth third on woofer, depending... It will fit though, no doubt about it and probably with only 4 components and an L-Pad.

Look at impedance though. I should have displayed electric phase too to see if there were any high angles. Amps don't like low impedance with large phase angle. The impedance itself isn't as big a deal as the phase when the impedance is low like that. I need to find a different set of L-Pad resistors to pad down the tweet. It's modeled using like a series 2.5 and a parallel 1.4 or something stupid like that. The issue is that with different resistors the phase changes too so it's a "gotcha" situation that could have been avoided if I'd chosen an 8 Ohm tweet. But there are always -alternatives-. And no you can't just do with a series before the crossover, it messes with the fs of the tweeter just like it would with a woofer. With the fs close to crossover like this is with large resistor values it will raise the Q and create a peak in the response. A proper L-Pad pads the tweet while maintaining the correct source impedance for the crossover that's behind it. Impedance is a two way street... ... And it's not purely resistive...
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Last edited by Siggma; 9th January 2013 at 07:04 PM. Reason: added humor, sp
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Old 9th January 2013, 07:22 PM   #42
Siggma is offline Siggma  United States
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Quote:
Originally Posted by tuxedocivic View Post
DrNick - RE Post 31.


That looks great. Nice cross over point.
Woops, thought you were talking to me...
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Old 9th January 2013, 09:30 PM   #43
DrNick is offline DrNick  United Kingdom
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Quote:
Originally Posted by tuxedocivic View Post
DrNick - RE Post 31.


That looks great. Nice cross over point. Good driver integration. Very flat response. Relatively simple cross over. Just to be clear though, you did enter driver offsets? Woofer z should be something like -0.025 if using the newer version of PCD. The older version should be 25.0 or something iirc.

This shouldn't make a terrible difference, it's probably fine.
There's always one more thing. I had mentioned this in a previous post and then forgotten. So, here is version 4, with the woofer at -25 mm in z.

Click the image to open in full size.

and with the tweeter reversed

Click the image to open in full size.

This is using this session file, and frd and zma files.

http://www.drnicholas.plus.com/Satellite/Satellite%204th%20with%20offset.csp

http://www.drnicholas.plus.com/Satel...0miniphase.frd

http://www.drnicholas.plus.com/Satel...0miniphase.zma

http://www.drnicholas.plus.com/Satel...ransformed.frd

http://www.drnicholas.plus.com/Satel...20modified.zma

The new crossover has only one inductor, so it is now third order electrically. As there is only one, I've changed it to have a lower resistance.

L2 2.00 mH, 0.1 Ohms
C2 12.00 uF

With a parallel leg over the woofer containing C 20 uF and R 20 Ohms. Before C2 was 15 uF, we had another inductor and only a 10 Ohm resistor in the parallel leg, so not a huge change, just enough to get the phase back in line.

The tweeter is crossover is unchanged from before, and has a third order section

C9 15 uF
L9 0.2 mH 0.2 Ohms
C10 25 uF

with a series resistor 2 Ohm after the crossover, and parallel resistor over the tweeter of 2.5 Ohms.

Thanks for reminding me of this! I'm hoping this thread will be insturctive, as everyone else can learn from each mistake I make.

Last edited by DrNick; 9th January 2013 at 09:34 PM. Reason: Spelling!
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Old 9th January 2013, 10:40 PM   #44
DrNick is offline DrNick  United Kingdom
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Originally Posted by Siggma View Post
Are you thinking of this pair up as a possibility? Can you get these drivers at decent prices?
I'm probably going to model a larger 6" or a metal cone 5.5" driver next, just to see what difference I can find from going up one size or a little in price, and to think what I might end up using for the main front speakers. I like the idea of the Seas U16RCY unit, as it fits in the same size cutout as most 5" drivers (12.6 cm), but has a larger piston area (99 cm2) than most, so the bass in a sealed box is better, so anything else will have to have more in the bass than this one, or fit in an even smaller box.

I've started modelling things in WinISD to check box sizes and the bass end. I looked at the CA18RLY 6.5" driver, but it needs 28 lires in a sealed box, so I might just try some other models.

All the best,

Nick.

Last edited by DrNick; 9th January 2013 at 10:43 PM.
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Old 9th January 2013, 10:49 PM   #45
Siggma is offline Siggma  United States
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Default SIGGMA-VV51-HT

Anyway, DrNick, here is the enclosure for the Visaton HT Sat along with speaker board before gluing it in place. I sprayed the interior with Quiet Kote to reduce any panel ringing and chamfered the interior of the woofer mount to reduce any compression that might occur. Tweet and woof will be surface mounted and I'll just have to live with any peaks and dips for now. I'll glue them up tonight and be ready for measurements in the morning. I'm also going to spray the back of the baffle before I glue them up. I'll get a pic if I can.

The official name of this is the SIGGMA-VV51-HT. SIGGMA (me) VV51 is Visaton 5" Vifa 1", HT.
Attached Images
File Type: jpg IMGP2704.jpg (299.7 KB, 62 views)
File Type: jpg IMGP2708.jpg (423.2 KB, 59 views)
File Type: jpg IMGP2709.jpg (240.3 KB, 57 views)
File Type: jpg IMGP2713.jpg (323.0 KB, 18 views)
File Type: jpg IMGP2714.jpg (295.1 KB, 16 views)
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Last edited by Siggma; 9th January 2013 at 10:58 PM. Reason: mention baffle
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Old 9th January 2013, 11:25 PM   #46
Siggma is offline Siggma  United States
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Forgot one picture. I added 1/2" round over on all baffle sides on front to reduce diffraction.

BTW, that Quiet Kote work GREAT. It sounds dead even banging on the outside. I might not even need any stuffing in the box. It will be even better once I get the box glued up. You can see my temporary cardboard crossover in the background...
Attached Images
File Type: jpg IMGP2717.jpg (324.8 KB, 19 views)
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Last edited by Siggma; 9th January 2013 at 11:52 PM.
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Old 9th January 2013, 11:34 PM   #47
Siggma is offline Siggma  United States
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Quote:
Originally Posted by DrNick View Post
I'm probably going to model a larger 6" or a metal cone 5.5" driver next,
You might check out the Visaton AL-130 Aluminum cone driver. It probably fits your specifications. It's a tad more expensive but has been successfully used in several projects. Paired with one of the less expensive Vifa tweets if I recall correctly, so there is a crossover designed for it somewhere. Yea, here's a goo link: TQWT Visaton AL130 & G20SC Finished!
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Old 9th January 2013, 11:50 PM   #48
DrNick is offline DrNick  United Kingdom
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Originally Posted by Siggma View Post
Anyway, DrNick, here is the enclosure for the Visaton HT Sat along with speaker board before gluing it in place. I sprayed the interior with Quiet Kote to reduce any panel ringing and chamfered the interior of the woofer mount to reduce any compression that might occur. Tweet and woof will be surface mounted and I'll just have to live with any peaks and dips for now. I'll glue them up tonight and be ready for measurements in the morning. I'm also going to spray the back of the baffle before I glue them up. I'll get a pic if I can.

The official name of this is the SIGGMA-VV51-HT. SIGGMA (me) VV51 is Visaton 5" Vifa 1", HT.
Cool, love the rounded baffle! I really appreciate seeing these, as I am going to have to wait till Next month at the earliest to go shopping for hi-fi again, so it may be a while before I can get going on whatever I end up making.

One thing I'm pondering is that the drivers that appear to work best in small enclosures when you model them in WinISD are often those intended for vented cabinets, but is this really true? As an example, the Seas CA18RLY is designed to work best sealed, and appears to give a flat response in 28 litres. The CA18 RNX, with the same cone (or very close) but a beefier magnet, gives less bass when sealed, but models with a flat response in 8 litres. The U16RCY that I'm looking at also appears to be a bigger magnet design that most people would be using in a bass reflex design. is there any problem going sealed with drivers like this?

Cheers,

Nick.
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Old 10th January 2013, 12:07 AM   #49
Siggma is offline Siggma  United States
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Quote:
Originally Posted by DrNick View Post
Cool, love the rounded baffle! I really appreciate seeing these, as I am going to have to wait till Next month at the earliest to go shopping for hi-fi again, so it may be a while before I can get going on whatever I end up making.
That might be better for you since it will give you a chance to "due diligence".

Quote:
One thing I'm pondering is that the drivers that appear to work best in small enclosures when you model them in WinISD are often those intended for vented cabinets, but is this really true? As an example, the Seas CA18RLY is designed to work best sealed, and appears to give a flat response in 28 litres. The CA18 RNX, with the same cone (or very close) but a beefier magnet, gives less bass when sealed, but models with a flat response in 8 litres. The U16RCY that I'm looking at also appears to be a bigger magnet design that most people would be using in a bass reflex design. is there any problem going sealed with drivers like this?

Cheers,

Nick.
The drivers you reference will have a different Qts. One will be higher (vented) and the other will be lower (sealed).
As for the question; No, many drivers will model for either sealed or vented but a sealed design might require too large an enclosure or a ported might require too low a tuning for a particular enclosure size, like the port is too long or the box is too big etc. Generally speaking high Qt (.4 and up) speakers go in vented enclosures and low Qt do best in sealed but that's a very general rule. Most of us wouldn't be using a high Qts driver in an enclosure. Usually those with a Qt over .6 are intended for open baffles. If the drivers Qt is high a small enclosure will raise the fc, and usually f3 as well, too much, unless you want or like a finished Qts over .7. What they are giving you (the colored slider thing) is the EPB (efficiency bandwidth product) which is a calculation that includes the Q and fs and maybe something else. It's a better predictor of enclosure use. But just because a driver has a high EPB doesn't mean you can't or shouldn't use it in a sealed enclosure. You can put any cone driver in either type of enclosure and get useful results with the exception of horn drivers which are specially made for horns and contact transducers (bass shakers) and other exotic transducers.
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Last edited by Siggma; 10th January 2013 at 12:09 AM. Reason: sp
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Old 10th January 2013, 03:32 PM   #50
Siggma is offline Siggma  United States
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SIGGMA-VV51-HT update.

I glued up the boxes and took a measurement this morning. Not good. I'm seeing a 5 db peak in tweeter response around 1.5K that's either from baffle edge diffraction or the woofer ring. Note the blue tweet response in the second image matches the predicted peak in the third image.

On the plus side, from the tweeter position my tweet and woof are only 2mm apart in time. The woof is actually ahead of the tweeter now. But that's at the new tweeter position.
Attached Images
File Type: jpg New Box First sim.jpg (610.0 KB, 22 views)
File Type: jpg new Box tweeter response.jpg (551.6 KB, 15 views)
File Type: jpg Baffle diffraction sim.jpg (334.6 KB, 12 views)
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Last edited by Siggma; 10th January 2013 at 03:37 PM.
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