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Multi-Way Conventional loudspeakers with crossovers

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Old 16th July 2008, 09:03 PM   #1
ceebmoj is offline ceebmoj  England
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Default new cabnets for b&w dm220

hi all,

I have just got a pair of b&w dm220 the cabinets are very scruffy but the cones seam to be good. are there any cabinets I can build to repace the exsisting cabnets?

blake
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Old 17th July 2008, 12:41 AM   #2
Shaun is offline Shaun  South Africa
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You could rebuild the existing boxes with same dimensions. DM220's are known to benefit from added internal bracing.
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Old 17th July 2008, 11:32 AM   #3
ceebmoj is offline ceebmoj  England
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hi there,

sounds like a good idea is it the volume of the cabinet that is most important i.e. if I wanted something a bit slimmer if I keep the same volume would that be ok?

Blake
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Old 17th July 2008, 11:59 AM   #4
sreten is offline sreten  United Kingdom
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Hi,

Have you considered refinishing the original cabinets ? Getting
an MDF box to look nice I'd suggest is considerably more difficult.

Click the image to open in full size.

For a slimmer (floorstanding ?) version you would need to rotate the drivers.

Unless you think the bass is dry the internal volume of the new version
used with the original port will not be too critical, e.g. 25% bigger will
be somewhat dryer and more extended.

/sreten.
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Old 17th July 2008, 12:20 PM   #5
Shaun is offline Shaun  South Africa
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The original orientation minimises centre-to-centre spacing to reduce lobing in the crossover region. This case is worse due to the big transition between driver sizes vs crossover frequency. If I were rebuilding those speakers, I'd consider adding a smaller midrange driver, such as the Dayton RS-52. But this is a bigger project than you are describing.

The B&W DM110 is a bass reflex loudspeaker with only a single woofer. I'm speculating that it might be the same woofer as used in the DM220's. If this is so, it could indicate that the DM220's woofer are suitable for bass reflex, too... in this case, I would also make it a bass reflex enclosure.
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Old 17th July 2008, 12:49 PM   #6
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by Shaun
The original orientation minimises centre-to-centre spacing to reduce lobing in the crossover region.
Not in the DM110, my opinion is its styling, and not very stylish.

Quote:
Originally posted by Shaun
The B&W DM110 is a bass reflex loudspeaker with only a single woofer. I'm speculating that it might be the same woofer as used in the DM220's. If this is so, it could indicate that the DM220's woofer are suitable for bass reflex, too... in this case, I would also make it a bass reflex enclosure.
I cannot remember if the DM220 is rear ported or not.
I suspect thinking about it that its not.
However if my brain cells are working correctly I recall the
220 drivers are rear coated whilst the 110 driver is not.
They are certainly versions of the same basic driver / chassis
/ magnet but if it is not vented, venting it is likely a bad idea.
(or might not be if TS parameters can be measured).

Either way if the bass is not already dry the box can be bigger.
If it is sealed, a vented version will likely need to be x2 volume.

/sreten.
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Old 17th July 2008, 02:47 PM   #7
ceebmoj is offline ceebmoj  England
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hi all,

thanks for the info. However what is dry bass?

I had a quick look at the speakers an thaer does not look to be any ports

Im very new to this the reason for rebuilding is that the cabinets are scruffy and I think that I can build something that looks better than the original cabinet.

blake
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Old 17th July 2008, 03:13 PM   #8
sreten is offline sreten  United Kingdom
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Hi,

Dry is subjective term like tight / loose, lean / fat. A speakers bass
can be extended but at the same it becomes lighter (but tighter).

For a sealed box there is nothing much to go wrong. The internal
volume is not critical, it is up to you how much you brace it etc,
and whether you use MDF, plywood or something more exotic.

It is a 2.5 way, so the top two drivers need to be closely spaced,
the lower bass unit can be moved down a floorstander if wanted.

If you have the skill an angled back floorstander will reduce the
hieght of the box needed for the tweeter to point at your ears.

/sreten.
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Old 17th July 2008, 04:06 PM   #9
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These are sealed boxes.

Slowly and gently press in one of the bass cones and the other will move out!

I love mine, even though it is cheap 70's chip-board with plastic veneer.

Unfortunately one of my drivers has sagged and the voice coil scrapes sometimes.

If you want a good home for a drive, throw it in my "skip"
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Old 17th July 2008, 04:18 PM   #10
ceebmoj is offline ceebmoj  England
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Hi,

thanks for the input guys. So if I have this right the important things for me to have in a new cabinet are as follows.

1. The smallest speaker (tweeter ?) should be at ear level when listening?
2. The order of the cones is not important?
3. The smallest speaker and the second speaker should be close together.
4. the new cabnet should be nice and rigid.
5. The volume of the speaker is not to important as long as it is simaler to the existing cabinets it will be ok

blake
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