Jamo Concert 8 Xover Coil Values

[Thomo]

Hi guys.

I just finished tweaking my Jamo xovers. I have rebuilt them on a piece of board mounted externally, hard-wired to do away with the pcb that was originally fitted.

Unfortunately I managed to snap the wire in the coil on the tweeter on one of them

Does anyone know the value of these coils please? I need to buy a couple of replacements, but don't have an inductance meter.

btw, I did solder the wire back together using some Mundorf Supreme solder, but the treble from this channel is veiled compared to the other side.

Cheers, Lee.

[infinia]

Originally posted by Thomo

btw, I did solder the wire back together using some Mundorf Supreme solder, but the treble from this channel is veiled compared to the other side.

Well then maybe Kester SN60 can return the unveiled sound?

Really recheck all schematic connections for errors and watch the coils orientation to one another and/or spacing to reduce cross couplings.

[Thomo]

Originally posted by infinia


Well then maybe Kester SN60 can return the unveiled sound?

Really recheck all schematic connections for errors and watch the coils orientation to one another and/or spacing to reduce cross couplings.

Hi, thanks for the reply. I have re-checked all connections and joint several times. I have removed the coils from the circuit and now both speakers are sounding the same.

I think I've monged the faulty coil removing it from the original board, as they were glued on. I melted the glue as best I could, but...

Cheers, Lee.

[infinia]

Originally posted by Thomo

I have removed the coils from the circuit and now both speakers are sounding the same.

I think I've monged the faulty coil removing it from the original board, as they were glued on.

Pretty sure on this, but I think wonked coils are better than no coils....Use ty wraps and remove the bobbin slowly to get better access? Hell, chewing gum and bailing wire (duct tape) might be useful.

[Thomo]

Yeah, you're right. The xover's for treble are 3rd order, which is a pain trying to work out the value of the coils. I am running them 1st order to make do at the moment with a 10uF cap which I think brings them in at 2500Hz.

I will have a closer inspection tomorrow at the bad coil, which has a lower dcr than the good one from the other speaker. It maybe some of the turns are shorted together and I can fix it.

I have posted the schematic, just in case anyone can think of some improvements/tweaks I could implement. I have upgraded all the components except the coils so far.

Cheers, Lee.

[dlr]

Originally posted by Thomo
Yeah, you're right. The xover's for treble are 3rd order, which is a pain trying to work out the value of the coils. I am running them 1st order to make do at the moment with a 10uF cap which I think brings them in at 2500Hz.

I will have a closer inspection tomorrow at the bad coil, which has a lower dcr than the good one from the other speaker. It maybe some of the turns are shorted together and I can fix it.

I have posted the schematic, just in case anyone can think of some improvements/tweaks I could implement. I have upgraded all the components except the coils so far.

Cheers, Lee.

I measured 0.25mH/1.3ohms for the tweeter coil.

Dave

[Thomo]

Originally posted by dlr

I measured 0.25mH/1.3ohms for the tweeter coil.

Dave

Thank you Dave. You have no idea how happy you have made me on a blustery and grey Monday morning in the UK.



I have been playing about with the values in LSP Cad Lite trying to calculate the coil value. I actually got pretty close (for a complete speaker noob) at 0.20mH.

Thanks again, Lee.