Modifying Diamond 9.6 crossovers

[derwhalfisch]

So I'm wanting to try bi-amping, but of course there are already passive crossovers in my speakers, and I understand I'll have to remove/replace, or at least modify these before I can make the most of bi-amping with an active (or software, at first) crossover.

The speakers have 'bi-wiring' binding posts, with the +high and +low, -high and -low paralleled by plates. I've traced the two crossovers out, in ignorant noob style as you can see I'm hoping somebody can help me identify the topology so I can determine where I need to cut a trace, add jumpers etc to disable the filters an active cross will provide.

I'm hoping there'll be a way of just skipping the first filter of each unit, drilling a hole and moving those input wires.

I'm not able (easily) to measure the inductance of those big coils, but if it's required knowledge, then I'll find a way :P I can tell you however that the mid/bass crosses at 150Hz, the mid/high starts at 1k, and crosses to the tweeter at 6k.

Cheers for your time, to anyone reading the thread ;P

[giralfino]

I don't think you can find the inductors value if you don't see a value printed on them or if you don't measure. This is specially true for cored inductors, for air core ones you can find the value from the wire diameter and the number of spires. If you want to measure go to that auction site and search for an RCL Multimeter, I bought an inexpensive one from China and it measures inductors very well.

Other things I see are: the resistor are 1.0 Ohm and 3.0 Ohm, the K printed is for accuracy, you need to find also the value of the big film cap (the meter will be useful also here), and finally, I think you have drawn incorrectly the woofer part of the xo: maybe it has the 2 inductors in series, and in between and in parallel the cap + resistor, so it would be a 3th order.

Ralf

[derwhalfisch]

Nope, I'm pretty sure I got the circuits correct. Thanks for the info though, I think I should be able to use some gear at the local air base :P I'm sure the dude there will have suitable meters

[giralfino]

I had a look at the Wharfedale 9.6, and it appears that they are some sort of 3.5 way, (or a 4 way) the first woofer is attenuated by the first coil only, and the second woofer is attenuated by the second coil only (but also by the cap).
BTW, are the 2 woofer identical?

Ralf

[derwhalfisch]

The woofers seem to be identical in construction except for the cone. They are unmarked except for Brand, a date stamp, and 'Model 20154' on the mid and 20155 on the bass.

[PeteMcK]

an interesting problem, how to bi-amp a 3.5way system; I suppose the easiest way is to leave the .5 driver inductor in place (your L1, bypassing L2), otherwise you'd need to tri-amp or convert the system to a 3-way.

your mid/high components need to stay in place, although the 4u7 cap and 1 ohm resistor can be bypassed.

[derwhalfisch]

Okay, thanks giralfino and PeteMcK.

[banjo4ever]

Hi I have a problem with the crossover for the diamond 9.6 crossover. One of the component SPIRIT 305J 220V has been identified as the problem. Can anyone help me with the specification of the same? The help will be highly appreciated!

[Gopher]

No you HAVEN'T got the circuits correct. Giralfino is right - those power resistors are 1 ohm (1R0) and 3 ohms (3R0), definitely NOT 1k ohms and 3k Ohms. The K represents the accuracy tolerance only.

I wouldn't mess with the inductors. The inductance isn't the only parameter of importance - the DC resistance is important too. If you switch to air cored types your DCR will change, as will your frequency response.

My advice:

1. change the cheapo power resistors to Mills MRA-12 non inductive 12W types.
2. change the cheapo non-polarised electrolytics and Spirit film cap to Ansar Supersound (CPA) film types.
3. upgrade the internal wiring to something half decent (preferably what you use to connect the speaker to your amp).
4. take the crossover outside the speaker and stick it in a WOODEN box, hardwiring the cables wherever possible to eliminate expensive fancy dan connectors.
5. don't waste your time bi-wiring. Electrically it makes no difference. Bi-amping WILL make a difference however.

JOB DONE.

[banjo4ever]

@Gopher: Thanks for you input. I will start working on that straight away. In fact I have already changed the cables. I will also look to get the better transistors and capacitors. I have one problem though, I have the capacitance values of all except, the 305J, 220 Volt needs to be replaced with? Should 3.0 Micro Farad 220 Volts should be OK?
I cant measure the capacitance, as it is faulty. (of course I could take out the other crossover and open it to measure the value). Till the time, I get the quality component I will need to replace the faulty SPIRIT 305J.