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In Reply to: RE: Great result ... posted by andyr on July 11, 2020 at 20:35:06
Andy, I have the 3.6R high passed at 200 Hz. Not using the external Magnepan crossover boxes. The house curve I created was eq'ed from 20Hz to 8000Hz with cuts only, no bumps. Not sure if this answers your question.
In regards to the GR OB/subs they integrate amazingly well with the 3.6Rs as suggested by Tim (emailtim). I would urge any Magnepan owner to consider them for sure. Phase was pretty easy to match with the Rythmik phase/delay dial requiring a 90 degree setting.
Rythmik amp plate also has a single PEQ feature which I used to tame one of my room modes prior to using the FIR eqs. as a final adjustment.
I did not have a choice regarding the wall construction...but a reminder that porous cement blocks on walls have a higher absorption coefficient of sheet rock. Additionally, the picture does not show that I have a total of 20 absorbing panels in the room with the back wall totally absorbant. My R60 is 534ms.
Seems a bit of a shame?
Now, you said " Phase was pretty easy to match with the Rythmik phase/delay dial requiring a 90 degree setting "; I'm very interested to know what process you followed to decide on the Rythmik phase being set at 90 deg.
(Is this something you can see from the REW graphs?)
I pretty much followed this procedure using REW in addition to lots of coaching from emailtim.
Here is Shumi's zoomed-in overlapping XO region phase plot of the right main(mid+high) and sub using Magnepan's 3.6 stock asymmetric overlapping points/slopes with the additional 90 degree Rythmik amp phase fine tuning.
Frequency Dependent Windowing has been added.
Note the matching slope and phase from [100-400]Hz through out the XO's driver overlap. The gold plot is all 3 drivers measured together.
Spent most of yesterday into the night evaluating 80,vs 90, vs 100 Hz croosovers with 3.6rs bass panels on, versus 3.6 bass panels off with lp at 250/18 and hp at 200/6.
I used mostly this reference recording for assessing changes. I know this recording extremely well.
Could not really make out huge differences in bass or other frequencies for 80,90,100 with bass panels on. Bass was ok, but I could barely make out the shakers on the right and the viola and violin did not appear to be separated by much space. Rebecca sounded ok. Piano appeared perfectly centered with the 3.6rs bass panels on. I was not prepared for the significant difference I found when I turned the bass panels off (took the external boxes off) and used the 10 B to bi-amp. Bass was punchier, deeper, and each note appeared well defined with bass being provided solely by the ob/servos subs, shakers came to life on the distant right even noticing that each shake was a bit different than the previous one, piano shifted slightly to the left and violin and viola appeared more separated. Guitar sounded better defined. With this configuration I thought I could even detect a spot in the recording where I thought Rebecca turned her head slightly while singing. I also tried subs on the outside of the speakers but did not gain anything at all in terms of minimizing room modes or anything else.I am done. I shall retain this configuration and not look back. This is what works for me in my room, with my equipment, and listening position.
Thanks for the update.
That instrument layout image is very cool. Never seen the sound stage information published before. More companies should publish that information.
If you have the 3.6 high passed at 200 Hz, you are hardly using the bass drivers of them as the mids are used to 200 Hz (if you have not chosen a different cut-off).
"... Not using the external Magnepan crossover boxes. ..."
He is not using the bass panels.
He is using the 3.6's OEM overlapping asymmetric XO points and slopes (LP250/18dB HP200/6dB) to actively biamp the stereo triple subs. He used the servo sub's plate amps phase adjustment to fine tune the phase matching.
I am doing a similar arrangement with my 20.1's but with different XO point slopes.
This has been done before and the following is the first time I am aware of. This image is from an old defunct/archived audio forum where a guy's bass panels went south. Considering the shipping costs for 20.X bass panel repairs, he made stereo OB/Dipole line arrays to replace the bass panels and gained extra extension in the process. If memory serves, he used 10" drivers here.
Not using the bass drivers of the 3.6 or the 20.1? A bit of waste to me. I think it would be okey to crossover at 80 Hz or so for the 3.6 and a bit lower for the 20.1.
I agree, the 80 Hz crossover needs to be evaluated for sure. My original plan was to start with that and then move up but I decided as a first step to try 250 Hz.
Here is an interesting video from Mike, the OCDHIFI guy who knows Magnepan speaker also recommending an 80 Hz crossover. Yes, Mike needs a belt for his pants!!!! He also has GR subs.
It allows for the subs to be placed outside of room modes without tainting imaging (don't have to move mid/tweets) which is a plus.
It also gets the bass coloration off the midrange and increases dynamic range in the bass/sub region.
FWIW, I get much better midrange clarity with my 20.1's doing this. I have also done it with my 3.6's.
Don't knock it until you have tried/heard it.
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