ATC SCM50 SL Clone

[vshvsh]

1. Does anyone knows the distance between the drivers on the original box ?

2. My main problem is that the ATC SM75-150S drivers I have are 4 ohms,
I can recone them but that will costly..

Can I use (or modify) the original crossover design (attached) to work with a 4 ohm mid ?

3. If anyone has box schematics or knows the exact inner box measurements it would be helpful.

[Inductor]

Originally Posted by vshvsh

1. Does anyone knows the distance between the drivers on the original box ?

2. My main problem is that the ATC SM75-150S drivers I have are 4 ohms,
I can recone them but that will costly..

Can I use (or modify) the original crossover design (attached) to work with a 4 ohm mid ?

3. If anyone has box schematics or knows the exact inner box measurements it would be helpful.

@2 Notice that final impedance will drop under 4 Ohms for your amp.
If is just a "sports" diy experience for your own use, I would do it. If a serious 8 Ohms loudspeaker to spec I would change drivers.
If you don't know how to design a crossover (and calibrate all components) don't do it...
You see, it's possible to design a 3-way with a 4 Ohm driver but might not be possible for you changing amplitudes, attenuations, xovers bands and all.

[vshvsh]

I'm using a push-pull tube amplifier (6L6) and the specs says it can handle 4ohms,
you think the final impedance will be lower than 4ohms?

also, the schematics I've attached are for the original crossovers designed by ATC.
the original speaker includes a 16ohm midrange driver and my driver is 8ohm,
this is the only difference.
do you think that it should affect the crossover design or just the amplifier impedance ?

I've built some crossovers before and these are for my own use.
I guess I'll buy cheap crossover components first so I can tune it..

[Inductor]

Originally Posted by vshvsh

...I guess I'll buy cheap crossover components first so I can tune it..

Good, I will have to congratulate you. Yes, they like to use the 16 Ohm from the spec in the specification sheet (page bottom). It is 10.5 Ohms (the 16).
Download Studio Bass Driver Unit specs (.zip)
ATC Loudspeakers. ATC Monitors. ATC SCM. ATC Speakers. Manufacturers of speakers, monitors, drive units and amplifiers.
You will be set at around 7-6 Ohms (more/less crossovers), what will be perfectly fine in your case. You know what to expect... a lot of work.
Can you simulate your work with frd/zma tolls/software?
I guess that first problem you will encounter is the xover frequencies not being adequate for the driver (from a small difference in impedance) all the other being the same.
You can do better than the stock crossover I guarantee you so, anyway...