New speaker project - Goodmans Magisters



  • edited July 6
    Latest tweaking has been in the digital domain.

    Despite painstaking research into what was sensitivity of the original Magister tweeters (Goodmans DT3), it turns out that they were less than the 91dB that I reckoned on. Hence the replacement 91dB Monacor DT-19SU were a little too sensitive. In fact a lot too sensitive!
    Thankfully, JRiver DSP Studio to the rescue again. As luck would have it, in JRiver's DSP Studio feathure, there is a parametric equaliser facility that includes a "high-shelf" cut. This cuts all frequencies from a selected point to a selected degree. Based on listening this turned out to be -4.9dB from 4910Hz (how's that for accuracy...?! ;-D  (the Magister's crossover frequency to the tweeter is (I think) 5000Hz, so I used that as a guide).

    Ideally of course, I would have got the sensitivity of the tweeters themselves exactly right. ;-)
    Although, tweaking the speaker crossovers themselves to the settings I achieved digitally through JRiver would have been impossible for me.
  • edited August 17
    Latest update.
    The ribbon tweeters are great.
    Also helpful is the results of the time I took to integrate them using the high-shelf cut.
    I'm as happy with the sound of the system as I've ever been. Really natural, revealing, and out-of-the-way. I think the lack of graininess of Col's Class A is really shining through. I'm chuffed to bits.


    ...Not so good is the fact that the speakers are reliant on the digital high-shelf to sound listenable. The 98dB sensitivity of the ribbon tweeters is way louder than the speakers overall. The shelf is now a -12.34dB cut, at 5107Hz using a 0.71Q slope (2nd order, 12dB/octave). Without the shelf, the speakers are 12.34dB too loud in the treble!. X_X

    I'm thinking of putting in an L-pad to make them more portable into other systems, but am not confident the degree of accuracy achieved by the digital high-shelf could be replicated using resistors. Maybe stick the L-pad in to make the speakers generally flatter, then tweak within my own system using the high-shelf....

    As an aside, the experience has left me thinking about the value of digital crossovers generally (if such things exist). Tweaking settings by ear to very fine degrees is surely more effective (and quicker) than using crossover components with relatively wide tolerances.

    Anyway, I must be feeling satisfied with the sound of the Magisters as today I felt driven to start on my next project ... <:-P
  • There are digital (and analogue) outboard crossovers (I'll find links later if nobody else comes up with them in the meantime). The crossovers should come before the power amp, so you're looking at bi-amping or tri-amping - a use for another of your rapidly breeding stable of amps?

    Funnily enough, I was talking about running my Royds actively to Colin earlier this week (I've been wanting to try a proper active bi-amped setup for ages). He came up with the idea of putting an analogue crossover circuit in the amplifier. Basically, I'll have a new quad-mono 25-amp SECA kit, with the crossover in the power amp case, fed from the pre-amp. Fewer boxes and generally neater solution. We'll see if it comes to pass.

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