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Old 28th March 2014, 06:45 PM   #21
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by giralfino View Post
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.
Perhaps Iím not explaining myself well enough, but Iím not looking for a mediocre system. And maybe I donít have the necessary experience to create a better than mediocre system, but thatís why I come here for help. Iím interested in building the loudspeakers myself and not simply purchasing a cheap 2.1 system and be done with it.

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Originally Posted by giralfino View Post
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.
Yes, I have explained my friend that bookshelf placement is not ideal for speakers, and he is aware of that. Failure is of course a possibility, but with my own experience in loudspeaker design combined with the help from both literature and other members of e.g. diyAudio, I am confident and positive that I will succeed.

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Originally Posted by giralfino View Post
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.
So what exactly was your advice? Going back through the thread I see only two suggestions from you: 1) free-standing tower speakers, and 2) Zaphís ZA-SR71 with reduced BSC and placed on top of the bookshelf. Both of these suggestions disregard the design criteria to have the speakers placed inside the bookshelf. Donít get me wrong here, Iím not saying I donít appreciate your input, but donít tell me I only want to listen to what I want to hear. I will consider all advice that respects the criteria described.

I understand you advise against making my own design. I am also skeptical about this approach, and that is why I was originally looking for a proven design. Since it seems to be difficult to find, perhaps I could take an existing design and adjust it for the unusual placement of the speakers. Before starting this thread I was looking at the 3-way SB 23/3 design made by the German DIY speaker guru Udo Wohlgemuth. As far as I understand this design was made to be placed near the back wall. What do you think about purchasing this design and adjusting the XO accordingly?
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Old 28th March 2014, 07:53 PM   #22
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Quote:
Originally Posted by soren5 View Post
Before starting this thread I was looking at the 3-way SB 23/3 design made by the German DIY speaker guru Udo Wohlgemuth. As far as I understand this design was made to be placed near the back wall. What do you think about purchasing this design and adjusting the XO accordingly?
SB Acoustics are good value drivers but this design probably has insufficient output at low frequencies for your room. Consider the "standard" SPL level of about 85dB average with peaks of around 20 dB. This is about the level in a cinema, the monitoring level in a studio and about the level to hear a "correct" tonal balance. One can argue +/- 5dB so it is only to get a feel. In your room the listening distance is perhaps 4m. If you compare the ported response of the SB Acoustic 8" and the 10" you will see the former has a significantly lower SPL because of the cone area but also exceeds the linear excursion limit over much of the range below 80Hz. The 10" is substantial better in this respect and approaches the required SPL to handle peaks cleanly.
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Old 28th March 2014, 08:42 PM   #23
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by andy19191 View Post
SB Acoustics are good value drivers but this design probably has insufficient output at low frequencies for your room. Consider the "standard" SPL level of about 85dB average with peaks of around 20 dB. This is about the level in a cinema, the monitoring level in a studio and about the level to hear a "correct" tonal balance. One can argue +/- 5dB so it is only to get a feel. In your room the listening distance is perhaps 4m. If you compare the ported response of the SB Acoustic 8" and the 10" you will see the former has a significantly lower SPL because of the cone area but also exceeds the linear excursion limit over much of the range below 80Hz. The 10" is substantial better in this respect and approaches the required SPL to handle peaks cleanly.
Good point! I did some sims for the Scan-Speak 10'' 26W/8534G00 in a 55L sealed enclosure. Attached you can see it compared to the 8Ē 22W/8534G00 in a 55L vented enclosure. It seems that I would get better SPL and lower extension for the 8Ē vented compared to the 10Ē sealed Both drivers are shown at 20W input. What would the benefit be of the 10Ē driver besides the greater power handling?
Attached Images
File Type: png Screen Shot 2014-03-28 at 20.27.24.png (465.9 KB, 173 views)
File Type: png Screen Shot 2014-03-28 at 20.28.56.png (484.8 KB, 139 views)
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Old 28th March 2014, 09:31 PM   #24
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Quote:
Originally Posted by soren5 View Post
Good point! I did some sims for the Scan-Speak 10'' 26W/8534G00 in a 55L sealed enclosure. Attached you can see it compared to the 8Ē 22W/8534G00 in a 55L vented enclosure. It seems that I would get better SPL and lower extension for the 8Ē vented compared to the 10Ē sealed Both drivers are shown at 20W input. What would the benefit be of the 10Ē driver besides the greater power handling?
Look at the maximum SPL plot for your ported 8" SB and the sealed 10" SS. Now look at the ported 10" SB (SB29NRX) which you may have to add. This is the point I was trying to make earlier about the benefits a more expensive 10" driver may bring. Not extending to lower frequencies but being able to cleanly play the low frequencies the small signal transfer function shows.
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Old 28th March 2014, 10:14 PM   #25
sreten is offline sreten  United Kingdom
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Hi,

What part of the ZD3C design do people not understand ?

A mid treble design axis 12" above the tweeter with the
tweeter above the mid unit - that sounds good to me.

Reduced BSC should help it survive in that location and
tone controls used modestly can tweak the bass balance.

There will be some inevitable cavity effects from the
adjoining units, but you can't design / predict for that.

I'd also use just one port, tuned lower, to say 33Hz
to go lower and increase the bass droop somewhat.
I'd offset the drivers and put the port between them.

A rather wacky idea would be to build boxes to fit
in each hole about 1cm less all round and then
line the hole with 1 cm foam with stiffer stuff
on the bottom of the hole to take the weight.
The boxes would not have to look pretty.
Its not half as daft as it may first seem, you'd
be decoupling all the large structure issues.

Regarding the 2cm issue, build grill frames 2cm
thick but extensively bevel the inside edges and
add a 1cm bevel to the outside front edges.
Recess the baffle 1cm in the hole.
(Is it really 2cm ? It seems a lot for a 2" ...)

rgds, sreten.

YMMV but short of measuring drivers in the
actual holes is hard to predict more. With
straight ahead speakers you need wide
horizontal dispersion, the SD3C excels,
and has the right control of vertical.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 28th March 2014 at 10:41 PM.
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Old 29th March 2014, 01:04 AM   #26
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by andy19191 View Post
Look at the maximum SPL plot for your ported 8" SB and the sealed 10" SS. Now look at the ported 10" SB (SB29NRX) which you may have to add. This is the point I was trying to make earlier about the benefits a more expensive 10" driver may bring. Not extending to lower frequencies but being able to cleanly play the low frequencies the small signal transfer function shows.
Right, I think I understand your point now. Here are the max SPL and transfer function sims of the 8Ē SS ported, the 10Ē SS sealed, the 8Ē SB ported, the 10Ē SB sealed, and finally the 10Ē SB ported. All cabinet volumes are 55 litres. The most expensive of the four, the 10Ē SB, also seems to be the one that plays the loudest and goes the deepest.
Attached Images
File Type: png Screen Shot 2014-03-29 at 01.01.58.png (480.5 KB, 128 views)
File Type: png Screen Shot 2014-03-29 at 01.01.29.png (476.9 KB, 120 views)
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Old 29th March 2014, 01:48 AM   #27
sreten is offline sreten  United Kingdom
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Hi,

Obsessing on bass is a great way to build a bad loudspeaker.
It only matters when everything else is very good to excellent.
Don't do it building anything for somebody else, be sensible.

rgds, sreten.


Don't get me wrong, I like good bass, but I'm pragmatic
about what matters and what is reasonable in context.
If you lose the big picture, you are not going to do well.

Loudest and deepest in a sim doesn't tell you anything,
compared to actual reality, sims don't do large signal.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 29th March 2014 at 02:11 AM.
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Old 29th March 2014, 01:55 AM   #28
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by sreten View Post
What part of the ZD3C design do people not understand ?

A mid treble design axis 12" above the tweeter with the
tweeter above the mid unit - that sounds good to me.

Reduced BSC should help it survive in that location and
tone controls used modestly can tweak the bass balance.
I thought the ZD3C looked great. You also seem to know what youíre talking about. I think they could work well for this project.

Quote:
Originally Posted by sreten View Post
I'd also use just one port, tuned lower, to say 33Hz
to go lower and increase the bass droop somewhat.
I'd offset the drivers and put the port between them.
Isnít 33Hz too low a tuning for these drivers? Or is that because of the in-bookshelf placement? Iíve attached a quick sim of the two RS180S-8 in a ported 55 litre enclosure tuned to 40, 35, and 30Hz.

Also, may I ask why you want to offset the woofers and place the port between them? I donít have much space on the baffle, and I donít think I should move the upper woofer closer to the mid? It could look something like the attached drawing.

Quote:
Originally Posted by sreten View Post
A rather wacky idea would be to build boxes to fit
in each hole about 1cm less all round and then
line the hole with 1 cm foam with stiffer stuff
on the bottom of the hole to take the weight.
The boxes would not have to look pretty.
Its not half as daft as it may first seem, you'd
be decoupling all the large structure issues.
I like it this idea! Makes sense to me.

Quote:
Originally Posted by sreten View Post
Regarding the 2cm issue, build grill frames 2cm
thick but extensively bevel the inside edges and
add a 1cm bevel to the outside front edges.
Recess the baffle 1cm in the hole.
(Is it really 2cm ? It seems a lot for a 2" ...)
17mm to be exact. I guess I could make the grille frames out of 19mm MDF then. I will get back with some 3D drawings later to make sure Iíve understood your suggestions for beveling the edges.
Attached Images
File Type: png Screen Shot 2014-03-29 at 01.27.24.png (356.9 KB, 113 views)
File Type: png ZDT3-soren2.png (19.3 KB, 16 views)
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Old 29th March 2014, 02:47 AM   #29
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK
Hi,

Basically line up the bass drivers with the mid/treble
or so and move the port to the left in your drawing,
for the left speaker, right would be mirror imaged.

Due to the grille you'll probably need to move the
T&M down somewhat to give room for the bevels.
There is no issue moving the drivers closer together.

Port tuning is an art in itself. What are the 3 major
room mode frequencies L&W&H of the intended room ?
Very often the square root of M1xM2 works well.

Sometimes you just tune low, below M1 if it works.
LxWxH of the room majorly affects bass response.

The placement here will exacerbate L and H, W less so.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 29th March 2014 at 03:13 AM.
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Old 29th March 2014, 01:13 PM   #30
soren5 is offline soren5  Denmark
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Quote:
Originally Posted by sreten View Post
Basically line up the bass drivers with the mid/treble
or so and move the port to the left in your drawing,
for the left speaker, right would be mirror imaged.

Due to the grille you'll probably need to move the
T&M down somewhat to give room for the bevels.
There is no issue moving the drivers closer together.
I havenít moved the drivers closer together in the attached drawing, just moved all drivers slightly down. Should I move the MT closer to the woofers, and perhaps the woofers closer together? By the way, what would you say is the minimum port diameter if using one port?

Quote:
Originally Posted by sreten View Post
Port tuning is an art in itself. What are the 3 major
room mode frequencies L&W&H of the intended room ?
Very often the square root of M1xM2 works well.

Sometimes you just tune low, below M1 if it works.
LxWxH of the room majorly affects bass response.

The placement here will exacerbate L and H, W less so.
Not sure what you mean by the three major room modes. The LxWxH of the room is 9.26 x 4.06 x 2.73 m. Iíve attached the floor plan of the living room and kitchen, which is one open space. The Ďwallí between the two rooms has been replaced by a ceiling beam. The loudspeakers position are marked with red squares.
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File Type: png ZDT3-soren3.png (19.8 KB, 21 views)
File Type: png Floor plan.png (91.9 KB, 36 views)
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