Are you planning to remove the grill to bypass the internal crossover for active bi-amping? It probably took Magnepan quite a lot of time and expertise to dial in that sound. Unless you're willing to spend hundreds of hours tweaking the frequency and slopes you will end up with a different sounding speaker than what Magnepan intended. You probably will like it better as you are self tuning it to your taste though. |
Yes I would bypass the crossover's completely.Hoping theres somebody out there thats done it that can help.+Pluses+,extra power,24db slope verses 6&12 db slope.I have everything to do it,if it's going to improve I want to do it. |
I have everything to do it,if it's going to improve I want to do it.
then why the heck are you asking - just do it! your system, your ears & your satisfaction. do it & ascertain for yourself if it's an improvement or not. why are you asking others for approval? study the present x-over & figure out if there is a phase reversal or not & figure out how your new x-overs will plug into the speaker seemlessly. Also figure out how you will reverse the whole thing & bring it back to factory spec. (BTW, I've noted your user-name so that I don't buy your specific Maggie 1.6s ;-) ) |
The woofer and tweeter crossover slopes are different (as you mention) but the break frequencies are also different. If you use a L/R crossover the break frequencies will be the same. Who knows how the speakers will sound. |
Do a search over at the "Asylums". Some suggest asymmetric slopes or xover points. With the Rane, or other 'pro' analog xovers, steeper curves than 12dB/octave are cascaded and introduce more noise. |
Hi Ngjockey,I went to Asylums and all over the web and found nothing on the subject of high slopes and noise.Do you know any other sites or pacific treads at Asylums dealing with noise.I thank all the plus factors outweigh the asymmetric slope but noise and how much?Quite a few people have gone active.I just want to try and get info before taking apart my Magnepans.Have you dealt with this before or heard any systems done active 24db? Chris at Rane nothing but++++ on active 24db.Any help or info appreciated. |
Don't have an issue with op-amps but doesn't it make sense. in general, that two in series will be twice as noisy as one? Whether that's noticeable depends on the implementation. |
Had the 1.6 and did exactly what you are considering - biamped with 24 db slopes. This was a few years ago and I can't remember the xover frequency but I am guessing it was around 1.5k. It was much more transparent with tighter bass. I played with the phase of the tweeter and I think I preferred normal phase. It's pretty easy to try this yourself. The speaker also becomes much more efficient.
G |
Thanks Grege,I'm going to hook up one channel passive,straight shot right out of my preamp to one amp to passive crossover.No other sub, Magnepans only.Then on the other side I'm going to hook up two way active, Magnepans only no other sub.Back and forth with balance.May the best crossover win. |
Sounds like a good plan Swordshield. Please report back your findings. That QR tweeter can go WAY lower than the standard passive xover, I think I went as low as 900 Hz with interesting results. |
I sure hope your wrong about freq.Manuel says 600Hz.Just got them going tonight,got the active set around 750Hz ,I thought for good measure to start out at.I want to retube my amps(just got amps- old tubes) before I make any conclusions.My mag .5's crossed over at 1000 Hz.I just set my 1.6 (active side) at 1000Hz [you freaked me out],were did you come up with this 900Hz.Manuel says exactly--- CROSSOVER SYSTEM Acoustical 600Hz, am I misinterpreting something here, is the word acoustical saying something I don't know.Don't want to fry them.Again (please) were did you get 900Hz? |
The electrical crossover is 1600 (maybe 1500).
The accoustical crossover is where the woofer and tweeter SPLs are equal. If you have a spectrum analyser, connect the tweeter with inverted polarity and look for a deep notch in the frequency response.
The inverted polarity of the tweeter is correct for the stock tweeter crossover (12 dB). For a L/R 24 dB crossover normal polarity is correct. (Otherwise you get that deep notch). |
Stereophile test shows x-over freq to be 600hz.
Knee frequencies are +- about 100hz from that.
Hi pass is 6db oct consisting of caps ONLY
Lo pass? 12db per octave and includes an inductor.
http://www.stereophile.com/content/magnepan-magneplanar-mg16qr-loudspeaker-measurements
As kind of an aside, I think this accounts for the tweeter sounding better on the inside, being 90degrees out of phase with the bass part of the driver. The tweeter being a couple inches closer to the listener, straightens that out.
Also, please note that this is NOT a difficult load. Very flat impedance with only a peak at crossover while phase angles remain moderate. Low sensitivity? Sure, but this is a line source / dipole and will react to a room somewhat differently than a box with forward facing drivers of similar electrical measure.
Best of luck with your experiment. Please post some results when available. |
Magfan... Yeah. I got ir backwards. It is the woofer that is 12 dB slope, and the tweeter 6 dB.
As to the crossover frequency, 1600 is what you get from calculations using the values of components in the crossover. The accoustic crossover includes mechanical characteristics of the drivers. No doubt that the accoustic frequency is what matters when listening to the stock speaker, but for designing a new crossover the electrical crossover is important.
By the way, I am a bit leary of driving any tweeter directly from a power amp. Power amps are apt to output nasty thumps. |
With 'ya on the thumps. A nasty thing to do to a tweeter. How about a turn-on delay relay? That help?
As for the x-over. I'm going with the measured results from Stereophile. The 2 drivers have very equal output at about 600 hz +-20hz. They are individually several db below 'average' output, and so the sum is pretty flat thru the passband. (right term?)
Also, consulting the measured data, it makes me even more convinced that changing the inductor to an ultra low DCR value is a mistake, raising output below crossover. This is already shelved UP vs the above-crossover frequencies.
Stock inductor is 16ga, iron core, of 0.40ohms DCR. You can easily buy an inductor in various configurations, down to <0.20 ohms DCR. No thought is apparently given to coil shape optimization.
My simulation yields a 14ga coil with as many turns as layers.....theoretically near-perfect. And, it is aircore with a DCR of about 0.38ohms, and will be inaudibly louder than stock. But, with near-zero chance of saturation at the very highest levels. The OTHER advantage of my coil, is that it uses Standard values of PVC pipe for the core. |
Magfan... I redid my crossovers using an aircore inductor with lower DCR (don't remember the value). However, if it slightly boosts the woofer output this means that there is less need for a tweeter pading resistor. Overall results are good. The speaker measures flat, but by the time that room equalization is done flat response is not needed. |
Darn it Eld, you are right! Less need for padding resistor, if you were so inclined in the first place!
In my case, I kept away from the urge to install one by the simple method of flipping my panels around and listening to the pole piece side. This is the 'old' orientation, changed in the 90's for some reason.
I find the 'old' orientation to be less beamy, less strident and having a wider sweet spot. This is with tweeters 'in'...formerly they were 'out'.
Please, call me Mag. That magfan things sounds so....formal!
Now the 10$ question.....When you redid your crossovers, what CAPS did you settle on? For reasons of cost / benefit, I'm thinking Clarity SA. with maybe a more 'premium' by pass of 0.1or less. |
Mag... I used Hovland. For best bang for the buck, and ease of work, I would recommend leave the Solens alone and put the $$ into a good inductor. |
