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Old 28th November 2013, 10:41 PM   #41
sreten is offline sreten  United Kingdom
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Hi,

AFAICT the Q35s are very unlikely utilising the full cabinet
volume and very probably have a sealed off bottom section
just begging to be filled with sand, easy to find that out.

rgds, sreten.
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Old 29th November 2013, 05:20 AM   #42
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They are sealed up. I did consider taking a jigsaw to them, making some measurements, and remaking the cabinets, but decided against it.

If I am going to go to the trouble of making new cabinets, I want a step-up in quality.

Taking into account your help, I still can't find the right speaker design.
I am heavily constrained by size - especially height and width.
If I take the design of a floorstander - for example the amiga or one of Troels' designs, and reduce the high by effectively taking the bottom off, can I simply make the deeper to maintain the volume without any detrimental effects?
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Old 29th November 2013, 05:20 PM   #43
jReave is offline jReave  Canada
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Quote:
Originally Posted by IanT1967 View Post
If I take the design of a floorstander - for example the amiga or one of Troels' designs, and reduce the high by effectively taking the bottom off, can I simply make the deeper to maintain the volume without any detrimental effects?
Essentially, can you do the same thing to other speakers as Zaph is suggesting with the ZD5 - change it from a floorstander to a stand mount?

It may in effect depend on the exact changes that you make but for the most part you can probably get away with it without a noticeable difference. The rule of thumb is that perceptually, we need a minimum change of 3db to notice a change in volume level (although for some, it may be about half that). This is why if a speaker's frequency response is measured as within plus or minus 3dB, then it's considered close enough to flat for our ears.

Below you can see the actual diffraction effects of the ZD5's large vs small baffles (floorstander is blue). Never mind the specific shape of the graphs (that is corrected for by the xo), but to answer your question, you should notice that there is really very little difference between them - less than 1dB difference at any given frequency (note the dB scale used).

Now if the largest change (the increase at about 1000Hz) also happens to coincide with an existing peak in the speaker right in that area and thereby increase it to something more noticeable, then yes, that might be a detrimental change. So it may be helpful to do a quick simulation for the actual speaker you're considering and compare it to its measured FR. If the changes are all within the smallest of margins, then you should be good to go.

I'm wondering now if a small high end 3-way monitor might be something that will work for you, but then again, they all may be too wide to be acceptable. Three builds come to mind but there may be more. In no particular order:

The Finalists - Speaker Design Works
The Statement Monitor - Statements_Monitor
The 3-way Classic - 3-Way Classic

However given your goals and constraints as I understand them and only wishing to build once, as much as I know that the ZD5 is going to be a big step up from your Kefs, I think the speaker that fits your requirements best would be something using the Satori driver. It's a cleaner and lower distortion driver than the ScanSpeak and it will have a little bit more authority in the bass department. And they just knocked a $100 off the price per driver this fall making them less expensive than the Scans now too.

Adelphos / Pair
Kairos (Pair)
Attached Images
File Type: gif BD flr vs stand.GIF (68.2 KB, 96 views)
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Old 29th November 2013, 05:50 PM   #44
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I have built several of the speakers designed by guys on the different forums including the ZD5s, the Amigas, Jeff Bagby's Continuums among others. The crossover for the ZD5s takes up a lot of real estate and did not fit in the sealed cabinet. That being said, those speakers and the Continuums are my favorites for being easy to listen to for long periods of time.
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Old 29th November 2013, 07:01 PM   #45
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Far too wide for what I would get away with .
I will have a look at the others later.
Ta.
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Old 29th November 2013, 10:05 PM   #46
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I can't find much about the Kairos, but am not keen on the look of them.
I can't find anything about the Adelphos build at all.
Does anyone have a link to the build details of these?

Ta.
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Old 29th November 2013, 11:44 PM   #47
jReave is offline jReave  Canada
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The Adelphos are an alternative to the Kairos. They use the same drivers as the Kairos but they are in a cabinet that does not have the slanted front baffle. Easier build and different aesthetics. As such, the drivers' acoustic centers are not physically in the same vertical line and Jeff B therefore had to use a different xo to get them right.

Sorry, I didn't realize that the Adelphos had no real documentation to them. Apply most of what you read about the Kairos to the Adelphos (well, besides the time aligned slanted baffle stuff.....), although I think Jeff does have a small preference for the Kairos (I think I've read that but I'm not 100% sure - I certainly don't want to misconstrue anything that he has shared with the DIY community).

The Satori is a 6 1/2" (165mm) driver so it looks like the cabinet is in the neighborhood of about 9" - 9 1/2" wide. Jeff also notes that Mark at Meniscus is flexible and will sell the plans and xo's only if you are able to get the drivers elsewhere.

If that's still too wide, you are really back into the 5 -5 1/2" driver territory again..... so back to the ZD5 and perhaps a few other choices as well. If it's a stand mount, then I would think that you'll want to go below its 60Hz F3 and therefore will need a sub (or 2). If a floorstander is ok, then its F3 of 30Hz should be fine since you don't need to push it for volume.

You could also consider making 2 side-firing subs in a narrow cabinet and putting those under the sealed ZD5's if that would be allowed. Or a narrow floorstander with a side-firing woofer. Almost the same thing but i think your amp will like the 1st option better.

Last edited by jReave; 29th November 2013 at 11:47 PM.
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Old 1st December 2013, 10:44 AM   #48
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In an earlier post, sreten said that R0 of the ZD5 should be rated at 10W.

Putting the crossover circuit into LTspice, and assuming a maximum input of 20Vrms, I get a maximum current of 2.8A through R0. This would require ait to be rated at 40W. Maybe I have made a mistake in the simulation, but if I have I can not see where.

I know this is unlikely to happen, but with a 3 year old, the volume could be turned up full.

Am I doing something wrong?
What assumptions do people make when deciding on the ratings of components?

Everything I design for work (Test equipment) needs to be designed for not what should happen, but what could happen. Do people follow this philosophy when designing speakers for home?

Again - I am concerned about where does all the heat go in this situation? I have no idea of the thermal properties of MDF, but suspect it does not conduct that well. Has anyone measured the internal temperature of their cabinets?
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Old 1st December 2013, 11:16 AM   #49
sreten is offline sreten  United Kingdom
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Hi,

If height is a problem a standmounter won't help as
correct tweeter height is the same as a floorstander.

http://www.humblehomemadehifi.com/do...Tempo_copy.pdf

You could squish the height a little and adjust depth
for the correct volume and use an on-axis design.

If its going to be low and angled baffle or construction
could help, though you can tilt a normal standmounter.

Yes you can "chop" the bottom off and add it to the depth.

A 10W wirewound can easily handle 200W peaks and
quite frankly your tweeter will fry way before it does.

FWIW running a 100W amplifier into mild clipping into
a speakers with decent quality material, the average
power into the speaker will be less than 30W.
(Peak power across the resistor will be < 30W.)
At normal listening levels much less, a few watts.

rgds, sreten.
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Old 1st December 2013, 11:58 AM   #50
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So if I work on the 'rule of thumb' that the resistor for music rating only needs to be 25% of rating required for a continuous sine wave I should be okay?

Does this mean it is safe to assume average current through the resistor in a music signal can be simplified to 50% of a continuous sine wave?

... and using the same assumption, inductor wires need to be rated to carry only 50% of what they would need for a continuous sine wave?
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