Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
71.62.217.11
In Reply to: RE: MMGi crossover update posted by jazzbeat on July 28, 2021 at 02:53:38
Well both speakers use 1st order filters for the LP and HP, so the slopes are the same but obviously the XO point of the MMGi is lower. That should take some strain off the woofer but not very much. The impedance of the MMGi is also nearly flat at 4 ohms and should be very easy to drive. The MMG has a impedance peak at the XO point, just like the 1.6, but again it should not present any problems.
I married the perfect woman - the downside is that everything that goes wrong is my fault.
Follow Ups:
I am inclined to disagree with your observation. The MMG uses a 2nd degree crossover on the bass / mid panel and 1st order on the tweeter. As mentioned earlier the amplifier had a difficult time powering the bass mid panel compared to my ET LFT 8s. Magnepan 1.7's, as well as orginal MMGs. As I did not notice however very obvious the 110 UF capacitor across the woofer and in such directly across the power amplifier output is not a great thing.
Generally in a 2nd order crossover the capacitor serves a secondary function in creating the low pass condition . Anything above say the 25 uf in this position is similar to driving a difficult ESL speaker.( most electrostatic speakers present a high capacitance load ). I am tempted to revert back to the orginal MMG crossover over time. The bass in my opinion with this version MMGi is not a winner.
I'm inclined to think you don't know what you're talking about.The pictorial you posted is a parallel network and the newer MMG's are series networks. Regardless, a 110uF (or large value) capacitor does not appear directly across the amplifier terminals in either case.
Any version of MMG crossover from original to present day is a benign impedance load for any decent amplifier. They are power hungry, but that's because of low efficiency and not an exaggerated or reactive impedance load.
Dave.
Edits: 07/28/21
Yes, But even in a series network it is second order with the values of the (mostly resistive) impedance of the alternate "driver" in parallel.
Nope, it is first order as the slopes of the filters are -6db per octave. The order of the filter is equal to the number of reactive components. Caps in parallel or coils in series are summed and count as one reactive component.
I married the perfect woman - the downside is that everything that goes wrong is my fault.
Sorry for the confusion but it is partly Magnepan's fault :). There are actually 2 versions of the MMG XO. The original had a 1st order LP and a 2nd order HP and, around 2000, they change to having both filters 1st order. They never changed the speaker designation. I just assumed you had the "newer" version.
I will recalculate and post and edit when I get free. Regardless the Bode diagrams are only the electrical response and not the acoustic response. Your ears hear what they hear.EDIT: A closer exam of the picture you provided seems to show all three caps wired in parallel (total capacitance =110.5 uF). I am pretty sure the crossover topology was changed to a 1st order series with capacitance across the woofer and inductance across the tweeter. This is in line with the rest of the x.7 family, the LRS and, interestingly, the SMGa which was the forerunner of the MMG and LRS. The inductor is not marked so I am not able to do the calculations.
I married the perfect woman - the downside is that everything that goes wrong is my fault.
Edits: 07/28/21 07/28/21 07/28/21
Hi thanks for the response. I will work with room setup at this end as well. I could be missing something . I did enjoy the sound I received in the overall sound but remember more bass response from the 1995 era MMG.
These are better in the bass with time. Have to believe the previous owner did not break these in. Curious hour many hours before these start to open up ? Thanks in advance.
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: