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Old 28th March 2014, 08:49 AM   #11
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If you go that way you need measurement capabilities.

Ralf
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Old 28th March 2014, 09:14 AM   #12
system7 is offline system7  United Kingdom
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Soren, I do wonder if designing an expensive built in 3 way is really what you want to do here.

I would be tempted to do a two way modelled in Visaton Boxsim. For wall placement.

Not hard to give it a smaller than usual bafflestep coil. Maybe 1mH. This thread will give you some idea of a good sounding filter:
DIY with Kef and Celestion

I would think 30-50 Litres reflex with a W200S bass speaker. Tweeter to suit. I use cone tweeters myself. Should come out a bit like the WLM La Scala:

Click the image to open in full size.
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Well, there it is! Best regards from Steve in Portsmouth, UK.
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Old 28th March 2014, 10:14 AM   #13
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by giralfino View Post
If you go that way you need measurement capabilities.

Ralf
I actually have a Behringer ECM8000 mic with a XENYX 302 USB mixer, which Iíve previously used for EQ and active subwoofer integration, but never for passive crossover design.
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Old 28th March 2014, 10:37 AM   #14
soren5 is offline soren5  Denmark
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Originally Posted by system7 View Post
Soren, I do wonder if designing an expensive built in 3 way is really what you want to do here.

I would be tempted to do a two way modelled in Visaton Boxsim. For wall placement.

Not hard to give it a smaller than usual bafflestep coil. Maybe 1mH. This thread will give you some idea of a good sounding filter:
DIY with Kef and Celestion

I would think 30-50 Litres reflex with a W200S bass speaker. Tweeter to suit. I use cone tweeters myself. Should come out a bit like the WLM La Scala:

Click the image to open in full size.
Thanks for the input, Steve.

Everything is relative of course, but I donít think my idea for a 3-way Scan-Speak would be expensive. I picked out some of the cheapest drivers they have. You should also take the budget into consideration and the fact that I donít really need to worry about cabinet finishing as the speakers will be built into the bookcase.

Of course a Visaton 2-way would be cheaper, but it would also give me less sensitivity and power handling, which I think would be nice to have in a large 60m2 room with 3m ceilings.

Anyway, thanks for the suggestion. I will have a look at the thread and the Boxsim software.
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Old 28th March 2014, 10:58 AM   #15
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Some (very) personal ideas about your project.

You never designed a speaker, and nevertheless you want to design a 3-way as a first project. The fact that your plan imply a speaker with tweeter not at ear level, a woofer near the floor and with a BSC unknown, and resonance from the partially void bookshelf are problems on top.

And more important, you are doing this for a friend. Think what can happen if the project won't succeed (and there is a big chance on that). For a friend I'd only build a proved design that he had chosen - period.

If your friend doesn't want a tower on the floor there is enough space on (not in) the bookshelf to place a, well, bookshelf speaker. Some designs even provide a reduced BSC option for this arrangement, see here for an example: Zaph|Audio - ZA-SR71

Ralf
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Old 28th March 2014, 12:04 PM   #16
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Originally Posted by soren5 View Post
Well, Iím intrigued by the idea of designing my own 3-way for this project, but Iím doubting whether I can expect as good results as e.g. the modified ZDT3 sreten suggested?
That is for you to judge. What makes the ZDT3 a good design? If you look at built in 3 way speakers used by studios what do they tend to look like and why? If learning to design a crossover is not something you are going to enjoy then it is probably unwise to pick it up as task.

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Originally Posted by soren5 View Post
Anyway, I was looking at the Scan-Speak Discovery range and there are some interesting drivers. What do you think of something like this?

Sealed 3-way WMT, 55 litres, F3 ~40Hz:
  • Woofer: 10'' 26W/8534G00 - 8 ohm - 89dB
  • Midrange: 5.5íí 15M/4624G00 - 4 ohm - 92.4dB (400-2500Hz)
  • Tweeter: 1Ē D2604/830000 - 4 ohm - 92.1dB
It looks like a solid starting point. You may want to consider woofers with more bass extension, possibly vented that still fit your volume but they will be more expensive.

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Originally Posted by soren5 View Post
If I choose to go this way, I would need some help with the XO design including adjustments for the unusual position of the speakers.
If you have Microsoft Excel (I don't) then you can download Jeff Bagby's set of speaker design programs and almost certainly pick up a fair amount of help and guidance on a forum like the Parts Express one (the help is the main attraction of the software). The software includes both baffle diffraction and I believe location near walls and floors. You can do this immediately using the published curves for the 3 drivers above and see how you get on. When the design has settled you can buy the drivers and repeat using the real curves which might tweak the odd value here and there in the crossover.
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Old 28th March 2014, 12:28 PM   #17
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by giralfino View Post
Some (very) personal ideas about your project.

You never designed a speaker, and nevertheless you want to design a 3-way as a first project. The fact that your plan imply a speaker with tweeter not at ear level, a woofer near the floor and with a BSC unknown, and resonance from the partially void bookshelf are problems on top.
I think those were actually some of the reasons to do my own design, since no proven design is tuned for this apparently unusual speaker placement.

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Originally Posted by giralfino View Post
And more important, you are doing this for a friend. Think what can happen if the project won't succeed (and there is a big chance on that). For a friend I'd only build a proved design that he had chosen - period.
Excuse me Ralf, but Iím just looking for advice here. I was actually on the search for a proven design, but as this turned out to be difficult, andy19191 suggested to do my own design.

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Originally Posted by giralfino View Post
If your friend doesn't want a tower on the floor there is enough space on (not in) the bookshelf to place a, well, bookshelf speaker. Some designs even provide a reduced BSC option for this arrangement, see here for an example: Zaph|Audio - ZA-SR71
Maybe I havenít made myself clear here. My friend and his wife are having their living room redesigned and together with the interior designer, who is also a friend of mine, weíre trying to included (hide) the stereo system inside the custom designed bookshelf. The primary objective here is design aesthetics and not sound quality. In other words, freestanding towers or speakers on top of the bookshelf is not an option. The bookshelf is going to be like I showed in my first post and the speakers will go in there. Iím trying to find the best possible solution given these restrictions.
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Old 28th March 2014, 01:05 PM   #18
soren5 is offline soren5  Denmark
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Originally Posted by andy19191 View Post
That is for you to judge. What makes the ZDT3 a good design? If you look at built in 3 way speakers used by studios what do they tend to look like and why? If learning to design a crossover is not something you are going to enjoy then it is probably unwise to pick it up as task.
Iím sure I will enjoy learning more about passive crossover design

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Originally Posted by andy19191 View Post
It looks like a solid starting point. You may want to consider woofers with more bass extension, possibly vented that still fit your volume but they will be more expensive.
If vented I would probably have to go for an 8Ē given the size restrictions. The 10Ē 26W/8534G00 in a sealed 55 litres gave me an F3 of 40Hz, but I need to simulate more. Perhaps the bass could even be extended with an LT circuit? I will do some more research about this.

Quote:
Originally Posted by andy19191 View Post
If you have Microsoft Excel (I don't) then you can download Jeff Bagby's set of speaker design programs and almost certainly pick up a fair amount of help and guidance on a forum like the Parts Express one (the help is the main attraction of the software). The software includes both baffle diffraction and I believe location near walls and floors. You can do this immediately using the published curves for the 3 drivers above and see how you get on. When the design has settled you can buy the drivers and repeat using the real curves which might tweak the odd value here and there in the crossover.
I have Excel yes, and Iíve actually played around with Jeff Bís software before. I will try to do some simulations.
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Old 28th March 2014, 01:25 PM   #19
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The primary objective here is design aesthetics and not sound quality. In other words, freestanding towers or speakers on top of the bookshelf is not an option.
Then fill the space with a simple 2.1 system. It doesn't make any sense to put a large amount of money on a mediocre system, if you don't have the necessary ability and experience to create a good solution. A 3-way is much more complex than a 2-way, and you have also some constraints on top of that.
But, again, the primary objective is really shared with your friend? What happens if the speaker won't sound good? You should take in consideration the fact that you could not succeed in designing a good sounding speaker. In other words, a failure can easily happen and you are blamed for the not good sounding speaker built into that beautiful and unmovable piece of furniture.

Quote:
Excuse me Ralf, but Iím just looking for advice here. I was actually on the search for a proven design, but as this turned out to be difficult, andy19191 suggested to do my own design.
I gave you my advice, but you don't want to listen. It is quite normal to only listen to what one wants to hear, but a wise person should realize a mistake, and understand if he is up to the task. I don't think that the project is not doable, but is for an experienced designer.

BTW, have you ever asked Troels Gravesen about what he wants to design the speakers you need? (don't know if he do such activities, but you don't have anything to lose).

Ralf
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Old 28th March 2014, 02:01 PM   #20
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Originally Posted by soren5 View Post
If vented I would probably have to go for an 8Ē given the size restrictions. The 10Ē 26W/8534G00 in a sealed 55 litres gave me an F3 of 40Hz, but I need to simulate more. Perhaps the bass could even be extended with an LT circuit? I will do some more research about this.
Extending the bass with circuitry is unlikely to be of much benefit because the driver has a limited linear excursion. A more expensive driver may have twice the linear extension and with the contribution from a port could maintain maximum SPL into the mid 30s.
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