crossover bypass

[back]

hello guys.

can anybody coment how this crossover works?


i would like to know what should i bypass to use an active

crossover.

thanks george.

http://www.infinity-classics.de/infi..._crossover.jpg

[sreten]

http://www.davidsaudio.com/Infinity_...Manual0001.pdf
http://www.davidsaudio.com/Infinity_...ummary0001.pdf
http://www.infinityclassics.de/Renai...ical_sheet.pdf

Hi,

I had a quick look at it and cannot work out what is going on.
Bi-amping is straightforward but the bass crossover is weird.

/sreten.

[back]

thanks the links are helpfull.

[sreten]

Hi,

Both coils have capacitors in series with them which is strange.

Your best bet might be to leave it as it is and set your active c/o
beyond the nominal c/o point of the bass unit which is 200Hz,
e.g. say 4th order L/R at 1kHz.

It may be possible to leave the components for the 2 ohm coil
in place and drive the 4 ohm coil directly but it will be different.
(i.e. 4 ohm direct || 2ohm with its c/o components)

Attached is a sim assuming resistive loading of the network,
this will be clearly wrong around the bass unit resonance and
wrong in other places due to inductance and coupling of the
coils, I've no idea what a correct equivalent circuit looks like.

Green = 4 ohm drive, Brown = 2 ohm drive.

/sreten.

I think even Svante's Basta! might struggle with the Watkins unit.
(This speaker simulator is very good at driver/crossover interactions).

[sdclc126]

If you are looking to replace the passive XO with active don't you just want to "bypass" the passive altogether? You can model a new XO for the active with software.

[sreten]

Originally posted by sdclc126

If you are looking to replace the passive XO with active
don't you just want to "bypass" the passive altogether?
You can model a new XO for the active with software.

Hi,

So how would you wire up the two coils on the Watkins unit ?
Or use two power amplifiers one for each coil ?
What software do you suggest ?

(Our posts probably crossed ....)

/sreten.

[sreten]

Hi,

This is what happens if you take out the two series capacitors.

It may be possible to drive 4ohms direct and remove the 882uF
from the 2 ohm drive network, and then add a subsonic filter.
Its very hard to say what happens with the real drive unit.

/sreten.

[speakerdoctor]

I believe the objective of bi-amping is to use electronics to control the crossover points. This approach negates the need for ANY passive components.
Trying to salvage the dual VC concept with active bi-amping is asking for trouble and probably not worth the hassle.

Attached is a suggestion to bypass all the passive compnents and wire your speakers inputs from your amps directly to neg and the 4 ohm taps of the woofer.

[sreten]

Originally posted by speakerdoctor

I believe the objective of bi-amping is to use electronics to control the crossover points.
This approach negates the need for ANY passive components.

Classic "bi-amping" uses all the crossover components.
The point is reduced current demands, e.g. a valve mid/treble
amplifier will still be swinging the bass voltages, but not the
current it would normally, reducing e.g. intermodulation.

Originally posted by speakerdoctor

Trying to salvage the dual VC concept with active bi-amping
is asking for trouble and probably not worth the hassle.

Attached is a suggestion to bypass all the passive compnents
and wire your speakers inputs from your amps directly to neg
and the 4 ohm taps of the woofer.

This is hard to say. What parameters / alignment will the driver
have when driven by a voltage source into its 4 ohm coil ?
The result could be overdamped / no real bass at all ....

/sreten.

The zip attachment is not readable.

[speakerdoctor]

Strange, I had no trouble opening it. It opens into a M'Soft Word .doc file. The file has the orig. poster's schematic which I've altered to simply show the passive components disconnected from the circuit and the + input connected directly to the 4 ohm red tap and neg. input going directly to the - tap on the woofer. It's a simple change the owner could try.

An active crossover is an adjustable device allowing the owner to optimize the woofer sound using a combination of the amp and e-xover controls. No need for the passives. If the passives stay in the circuit you might as well simply bi-wire instead.