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Old 21st December 2006, 04:10 PM   #1
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Default Q on Heybrook HB2 XO

Here's a schematic of the XO for the Heybrook HB2's -- the woofer for this one was destroyed by too much teenage activity so it is in the woofer replacement facility -- why is R1, C2, L3 connected to the tweeter "+" ? when I simmed it I note that it "shelves" the response. The tweeter seems to be the standard, government issue Audax 1"

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Here's what the actual response into a resistive load looks like:

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Old 21st December 2006, 04:45 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

as drawn R1, C2 and L3 make no sense at all, especially as R1 is 560 ohm.

I suspect they are across the tweeter, r1 = 5.6 ohm
tuned to fs of the tweeter to flatten its impedance.

/sreten.
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Old 21st December 2006, 05:15 PM   #3
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I have checked it twice and measured the value of R1 - 560 ohms - I posted this as I thought they may have made a mistake.

I redrew the schematic to better illustrate the tweeter connection.
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Old 21st December 2006, 06:42 PM   #4
sreten is offline sreten  United Kingdom
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Hi,

well the L & C component values look right for the job.

R = 560R is completely pointless. Where its wired across is pointless.

Screw up ? hardwired ?

/sreten.
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Old 21st December 2006, 11:08 PM   #5
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No, I am not kidding:

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Old 22nd December 2006, 10:06 PM   #6
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Hmmmm, here's a pair of phase-gain plots of the Woofer section of the Heybrook XO -- the first with R1, C2, L3 connected as illustrated, the second with the network disconnected:

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Old 27th December 2006, 12:25 PM   #7
Svante is offline Svante  Sweden
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I agree with sreten that it looks completely pointless to have them connected as in the diagram. It looks as if someone has misinterpreted a circuit diagram (twofold, first the 560 ohms, then where they are connected).

Is the diagram an original heybrook diagram or is it drawn from the actual components in the box? Are the components connected the same way in both speakers?
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Old 27th December 2006, 03:30 PM   #8
ch83575 is offline ch83575  United States
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Easy there guys! I think you should be a little slower to assume that jackinnj cant even follow some wires! This circuit might not be familiar to you, but it obviously does something and I think jackinnj's idea here was to spark a conversation about it, not get accused of being stupid.

I mocked up the crossover both ways and the additional components are very interesting to me. They seem to be making the electrical phase more symetrical and closer to the a standard 4th order target (i cant tell which one). I am still new to this so I am not sure if I am even on the right track, but at least I give my fellow DIYers the benifit of the doubt .

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Click the image to open in full size.

-Chad
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Old 28th December 2006, 02:05 PM   #9
sreten is offline sreten  United Kingdom
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Hi,

As far as I'm concerned I can't see any audible point of the circuit.

If R should = 560R then the type of inductor is totally wrong.

If you redraw the circuit to look like a normal crossover it
looks like a blatant wiring and a component selection error.

The question was have they made a mistake, the answer IMO is yes.

Fc of the circuit is 1950Hz, which could easily be the tweeter Fs.
In that case it shoulds in parallel with the tweeter, R = 5.6 R.

Its also possible at 2K its there to control a bass unit resonance,
or shape the response. In that case it shoulds in parallel with the
bass unit, but R ? who knows ? 5.6R is the place to start.

But usually the latter is a series circuit (for good reasons), and
as the tweeter has a zobel my money is on the former option.

/sreten.

Are both speakers the same as Svante asked ? (probably are)
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Old 28th December 2006, 02:15 PM   #10
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by ch83575
Easy there guys! I think you should be a little slower to assume that jackinnj cant even follow some wires! This circuit might not be familiar to you, but it obviously does something and I think jackinnj's idea here was to spark a conversation about it, not get accused of being stupid.

I mocked up the crossover both ways and the additional components are very interesting to me. They seem to be making the electrical phase more symetrical and closer to the a standard 4th order target (i cant tell which one). I am still new to this so I am not sure if I am even on the right track, but at least I give my fellow DIYers the benifit of the doubt .

-Chad
Hmmm.......

The only person jumping to assumptions round here is you.

/sreten.
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