B&W 804 Nautilus, crossover schematic filter - diyAudio
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Old 23rd February 2009, 09:29 PM   #1
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Default B&W 804 Nautilus, crossover schematic filter

Can anyone of you guys point me to (link, email, whatever) schematics crossover filter of B&W Nautilus 804 ?

Thanx in advance

Giuseppe
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Old 27th February 2009, 08:52 AM   #2
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Hi,

There has been a 'Boxenklinik' article about the nautilus 804 in "Hobby Hifi", where they designed a new filter for it.
Interesting loudspeaker magazine.

Sorry, no scanner here.
I think you can buy back issues.

http://www.hobbyhifi.de/Archiv/07/04_07/04_07.html

I cannot remember if the original schematic was in the article.
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Old 27th February 2009, 01:21 PM   #3
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Many thanks, the information was very useful, the journal contains the schema.
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Old 28th February 2009, 11:36 AM   #4
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I think the filter shown in the article is the one designed by HH, not the original.
Are you going to try the new one?
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Old 29th December 2012, 06:35 PM   #5
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Has anyone tried modding N804 crossovers ?

I've looked for a copy of Hobby HiFi April 2007 - but no luck.

Any suggestions ?
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Old 29th December 2012, 09:59 PM   #6
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The Nautilus 804 has 3 crossover boards - one for the tweeter, FST mid range unit and one for the 2 LF drivers.

All 3 crossover boards can be accessed by removing the LF drivers.
So the FST mid range unit does not need to be removed to get access to the mid or HF crossovers

The HF crossover board has
L1 - small air core inductor
C1 - 4.7 uF length = 1 3/8"
C2 10 uF length = 1 3/4"
R1 = 2R2 11 watts - with Bennic inked as the make

My experience with commercial wire wound resistors - used for audio - is that they sound harsh.
A harsh sounding resistor, in series with a Nautilus metal dome tweeter, is less than ideal.
So replacing the 2R2 resistor with a Mills or Mundorf would probably improve the sonics.

Replacing the 4u7 cap with a Mundorf Supreme or Silver Oil would certainly make an improvement - however, I'll have to check if one will fit.
Another option maybe replacing it with a Mundorf EVO gold silver oil cap.
But have yet to hear the new EVO gold silver oil caps

Here is a photo of the Nautilus 804 HF board.
.
Attached Images
File Type: jpg img_0917_2.jpg (487.8 KB, 198 views)
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Old 29th December 2012, 10:45 PM   #7
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ancestrale,
Unless you have the exact same drivers which I would doubt why would you want to clone that crossover? Just from the simple description of it it doesn't sound like anything special, actually sounds rather like a crude 1st order network. As for all the hype about oil filled whatever save yourself a lot of money and buy some good polypropylene capacitors and quality large gauge inductors.
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Old 29th December 2012, 11:41 PM   #8
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Quote:
Originally Posted by Kindhornman View Post
As for all the hype about oil filled whatever save yourself a lot of money and buy some good polypropylene capacitors and quality large gauge inductors.
Thanks for your response.

Moving from the original B&W Nautilus series from the 1990's, to the Diamond series,
B&W improved the crossover components to upper end Mundorf's in key locations.
They used regular MKP's in non critical locations.


With my B&W 603 s2's, I replaced the caps in series with the tweeter
with an AuriCap and a Mundorf Supreme.
The series resistor was replaced with a Mundorf metal oxide.
The AuriCap and Mundorf Supreme seem to complement each other quite well.
I made these changes one at a time, and each change, for whatever reason, reduced harshness.


As you've pointed out, an original intent, of opening up my N804's,
was to see if the inductors connected to the LF drivers, could be replaced
with ones that have a lower resistance.

However, looking at the LF board, I can't see any markings for the inductor values.
So they would have to be pulled out and their values measured.
I'd use a frequency sweep of an LCR circuit and find the resonance.

If they were to be replaced, almost certainly ferrous cores would be needed.


Here is a photo of the N804 LF crossover board.
Attached Images
File Type: jpg img_0886-2.jpg (495.4 KB, 166 views)
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Old 30th December 2012, 12:02 AM   #9
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The diameter of the magnet wire, on one of the LF inductors, consistently measures at 0.044"
This converts to 17 awg - but I would have expected an even gauge like 14, 16 or 18 awg.
However, 0.044" is the diameter that consistently comes up.
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Old 30th December 2012, 12:54 AM   #10
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Uunderhill,
This is my opinion and I am sure there are as many of those and people who will answer this thread. If you want to improve the sound of your B&W speakers I would look at a few things. As you have seen B&W like most manufacturers look where they can cut corners. One is in the quality of the crossover components. I would think about air core inductors for an improvement and not an iron core inductor. This is a cost saving move, a larger wire diameter and no iron core will take the core saturation out of the picture that you now most likely have. Yes you would have to take the inductor out to get the value. If you really want to make a significant difference you would be much better off trying to add a Zobel network to the devices to flatten the impedance rise in the devices. The next move up as far as I am concerned in a passive crossover would be to go to 4th order crossover designs but that would be a major change and unless you can measure the speaker parameters that would be a shot in the dark. I can't help you go past this point as I don't have any specific information about the devices.
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