View Full Version : Active Crossover for M30
06-03-2009, 03:12 PM
I?m interested in a active crossover for my pair of M30. Do you think this is a good idea and is it available?
As a matter of interest how would you commence the design and what test equipment would you be using?
It is absolutely impossible to make a successful active crossover for a passive speaker unless you have an intimate knowledge of the entire speaker's drive units, dimensions and current crossover network. I've covered that here (http://www.harbeth.co.uk/usergroup/showthread.php?p=4579#post4579).
06-03-2009, 04:38 PM
thanks for your quick reply!
A friend of mine (who knows a lot more about electronics than me) has recently activated a pair of ATC SCM 50. He?s a recording engineer and has ordered active crossovers from ATC which was possible. The result is stunning. So I thought it?s a good idea to activate my M30 too (with the help of my friend). I?ve read in your prospect for Pro-User there?s an active version of the M30. So you?ve already developed an active crossover for the speaker. Is it possible to order this seperately and use it to activate my M30?
I regret that I can't offer you an active version. If your friend was supplied with active filters from the factory then, of course, he should be able to activate his passive speakers. But as we can't supply the active electronics then you would need to start the project from the very beginning - and that means months of work.
06-03-2009, 05:49 PM
what a pity! Perhaps you can offer it sometimes in the future. There must be a reasen why so many pro?s use activated speakers. In my experience there?s much more control.
08-03-2009, 01:14 PM
Being an ATC owner (of 100A's once and currently 20ASL Pro's), I'd say that "activating" the 50's is the best thing that could have been done with them!
It's not for me to go into any real detail of another company's products here, but I think I can say that there is a definite need for exact driver matching in three way ATC's that use their dome mid driver, especially in the phase matching at the crossover point between bass and mid unit (easy to set if you know what you're doing and have the proper test equipment to do it). The active amp packs allow this, as well as the usual fine level adjustments normally seen. Remember too that the amps are specifically designed for the 16 Ohm driver load too.
For years, I thought that "active" was automatically better, the losses in a passive crossover being far greater than any well designed active circuit, but having recently inherited some old Spendor BC2's (with later bass units) and having owned BC1's, Yamaha NS1000's and Harbeth HL5's in the past, I'd confirm today that a well designed passive speaker where all the design parameters have been carefully mixed together doesn't lose anything that a well specified driving amp can't cure to be honest (in my opinion, some other active speaker manufacturers seem to cripple their passive crossovers to make active a necessary upgrade, making the active option part of their costly upgrade path. Not many have the ability to do it properly as a matter of course [Meridian/ATC/Harbeth M40's?]).