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In Reply to: RE: Current Maggies run full range compared to high pass and subs. posted by ColinB on December 28, 2020 at 17:23:48
The benefit of high-passing the speakers has been known for decades. This is hardly a secret revealed.
The guy in the video doesn't seem to know much about the speakers actually.
Around seven minutes in he completely mischaracterizes what the buttons are for. :)
It was impossible to take him seriously after that.
Dave.
Follow Ups:
The guy in the video is a hack that sells a lot of useless expensive kits to unsuspecting naive Magnepan owners.It looks like his website is down, but if you read some of his verbiage, you get the idea.
"...
3) Place mini AudioFoil (did he misspell Audiofool ???) speaker cables between xover and panel
4) Poop your shorts at the gains you receive.
5) Clean yourself up and go back for listening.
..."https://www.verastarr.com/magnepan-fuse-bypass
The subs in his videos are Danny Richie's DIY Servo Sub kits from GR Research.
https://www.gr-research.com/diy-subwooofer-kits.html
Edits: 12/28/20
He seems like a complete clown to me. Oh well.
Thx.
Dave.
Thanks Dave,
Ah yes. I remember now that the buttons are for tensioning the panel to a certain freq, not for what he says.
Is there a chance the speaker amp is clipping a bit at the start when the speakers are run full range? Or is this just all likely down excursion issues/IMD when run full range?
How about the max vol capability of the current Maggies range with 1st order XOs compared to the older range with higher order XOs.? (When run full range)
Cheers
Colin
There's a certain amount of IM distortion "built in" to the speaker because of the mechanical crossover between the drivers. You can see this by exciting the woofer transducer and monitoring voltage on the tweeter transducer. (Or vice-versa....although not nearly as easy to see.)The "first-order" series crossovers obviously broaden the drive levels to each transducer and "blend" the drivers even further. And the single-ended operation causes more even-order distortion components. These are speakers not without significant distortion. :)
The electro-mechanical nature of these transducers has an inherent 2nd-order roll-off below resonance. Including dipole cancellation you net an approximate 3rd-order roll-off. Thus, I think it's appropriate to add a first-order electrical filter to the power amp drive that matches up (the best you can) with that 3rd-order roll-off point.
You then have a 4th-order acoustic roll-off which can be matched up to a subwoofer low-pass pretty well.That's my preferred way to operate the smaller Maggies.
Higher-order crossovers are popular too but, to me, it's difficult to blend them correctly.That said, and all other things being equal, rolling off the bass frequencies to the main panel will reduce all forms of distortion from the speaker....driven at the same nominal SPL level. That's just basic physical limitations at work.
Dave.
Edits: 12/28/20
But surely, Dave, if you do it this way ... you're not actually cutting off much low end from the Maggie bass panels? So you're still getting into single-magnet distortion territory.
Whereas if you cut them off higher - say 60 or 80Hz (with a 24dB L-R filter) - you avoid getting into excessive distortion territory ... plus reduce the load on the amp.
Andy
Yeah I had thought about this possibility too. I would probably try both methods and see if the first order method at bass roll off makes enough difference regarding distortion and max vol capability/congestion etc. I would imagine it would not be as good as a higher order electrical XO at higher freq but it might help somewhat compared to running the speakers full range, anc could make enough of a difference.
Better potential integration with a sub sound like a good positive of the first order method, and I suspect the bass extension and output of the speakers might not be too much different to running the speakers full range, which gives you the option of not using a sub too (if you want too) which isn't possible with the other method.
Perhaps this depends on which active path you go down?
Certainly with an analogue active filter, it would be difficult ... but my miniDSP unit (initially a 10x10HD) and now a nanoDIGI) enables me to store 4 configs and select one of them 'on the fly'.
So one config is "bass panels full range and subs off" - which is easy to compare against "bass panel / sub XO at 80Hz, 24dB L-R".
Andy
Yeah good point. The newer Minidsps are v flexible for sure. Those presets sound v handy. You could also try the first order HP either subs method mentioned above and compare to quickly to the others.
I'd probably still prefer to go down the HP PLLXO route with analogue active LP XOs though, but it's more work and no easy way to switch quickly to compare.
You are always in "single-magnet distortion territory" with these speakers. (Unless you have 20-somethings.)
There are advantages in higher-order/higher-slope schemes. (I don't believe I said otherwise.)
Yes, distortion would be further reduced, but you don't have the best integration (in my opinion) between main speakers and sub-woofers using that approach.
As you know, there are trade-offs at every turn with speaker systems. :)
Dave.
not using your suggestion of a 6dB HP filter which coincided with the intrinsic low end roll-off of the bass panel ... but, rather, moving the roll-off higher.
The fact that you do this forces you to use a higher-order HP filter, as you need to compensate for no longer having the "intrinsic low end roll-off".
Andy
That's interesting. Why would the integration potentially be better with the first order HP at speaker bass roll off freq method? because the XO is at a lower frequency and the ear is less sensitive to phase issues etc there?, or for another reason?
Thanks for the info. Much appreciated. That's a handy tip to get effectively a 4th order acoustic roll off. I assume a pllxo (single cap) to get that first order HP before the power amp is ok to use? Might this method produces better blending with a standard kind of sealed box sub or would you really still need dipole subs and eq etc?
I have had good luck with a minidsp to perform biamping and subwoofer blending.
Looks good, but how did you get the HSU subs to blend well? Those subs are ported and would surely be quite a lot slower than the Maggie panels. I only found sealed box subs to work ok (but still with some issues...). I prefer the bass from the Maggies panels as it's faster etc and better integrated. I really want a 20.x or the 30.7 and run them full range, but this looks like a good solution for a smaller model like the 1.6.
having four subs evens out the bass response in the room. The nanodigi crossover I have set is 24/db which also helps to keep the bass out of the magnepan response region of the 1.6's. Kinda of like my own version of the swarm system.
http://www.audiokinesis.com/the-swarm-subwoofer-system-1.html
Yes using many subs definitely evens out the bass response and is nice. What I meant was a ported sub won't stop and start like a sealed one can and is even further behind a Maggie panel in that regard. Would be interested to hear this setup. Appreciate that keeping the Maggie freq range separated from the sub range would help integration though. If it was me I'd probably only be using sealed subs though, based on my previous tests with different sub types.
Satie (is he still around?) used to recommend using bipolar sealed subs if using box subs. He reckoned they integrated better with Maggies than one driver box subs. Vanderstein used to make a few bipolar subs.
The 2 HSU TN1220's in my setup are tuned at a very low frequency, something like 18hz. So an octave or so above that they behave similar to a sealed subwoofer.
The 2 SVS SB-1000's are sealed.
The sound especially in the base region is very natural and seamless sounding in my setup.
I have a significant amount of bass trapping in the room.
Sounds interesting. Using ported and sealed subs together, and getting both of the types of bass radiation patterns.
In the past I could never get ported subs (on their own) to integrate well with some Maggie 3 series . I used some big ones too that were tuned very low. They were just too slow. Like a dinosaur! I got much better results from not so big sealed subs. The REL strata III worked quite well but was still a little slow. Quite a few people used to use those IIRC.
Mind you I have little experience of using integrating subs with a minidsp and having the ability to tune it so much there.
Sounds interesting. Using ported and sealed subs together, and getting both of the types of bass radiation patterns.
In the past I could never get ported subs (on their own) to integrate well with some Maggie 3 series . I used some big ones too that were tuned very low. They were just too slow. Like a dinosaur! I got much better results from not so big sealed subs. The REL strata III worked quite well but was still a little slow. Quite a few people used to use those IIRC.
Mind you I have little experience of using integrating subs with a minidsp and having the ability to tune it so much there.
It's the low-pass behavior of the subs that necessitates the type of integration. This is defined (and not alterable) in many cases, so you'd probably want to try and match that.....whatever it is.
Whether the sub is dipole or sealed-box is another aspect. I think it's preferable to use dipole subs, but box subs are much more available and easier to get started with.
Dave.
Thanks for the info. I see. So if your sub's own control had a 4th order LP, for example, the method of first order on the Maggies at their bass roll of point might work ok?
Would a PLLXO (single cap) be ok to use before the speaker power amp to get that 1st order HP or would you be better off using something like a minidsp?
This 1st order HP method you suggested obviously doesn't have as much filtering as if you rolled up the Maggies higher up, say at 80 Hz with a 4th order active HP. Is the former method sufficient in removing enough low frequencies in the signal to protect against excursion, and get a fair amount of higher max volume?
Appreciate dipole subs will integrate better than box ones. I tried an open baffle sub before in my system but it never worked well. Looks like you need quite a few very light drivers, and preferably a servo amp. That GR research sub setup isn't too cheap I guess..
A simple capacitor in front of your amplifier will yield the first-order slope, but that only works correctly if you're using the natural roll-off point of the Magnepan's.
If going up higher, like maybe 80Hz, then it's a different scheme and you'd need to adopt a different approach.
A low frequency first-order filter isn't going to help out too much on bandwidth-limitation relative to a 4th-order electrical filter at 80Hz. If a person is looking to play the main speakers a good bit louder than they're capable of driven full range, then the higher frequency/order crossover is preferred. But, (smaller) Magnepan's are limited in their SPL capability anyways, so you can quickly get to the point of diminishing returns.
Dave.
Thanks Dave.
Yeah that's what I thought. In that video I guess the 4th order active Hp he uses later on in the vid is providing a bit more max vol without distortion, but the small Maggies have limited vol anyways so probably not a huge different to using a first order at Maggies bass roll off freq as you suggest.
I was curious as to whether the distortion you can hear when he runs the Maggies full range at the start of the vid is all due to max panel excursion etc, or if the speaker amp might be clipping a bit too. Guess there is no way to know for certain without measurements.
Thanks for the first order HP tip at the Maggie bass roll off point. It might provide a touch more max vol, less congestion, a bit of driver protection, and might also make sub integration easier. I'll be trying that in the future with the bigger Maggie models. I would assume that the bass extension of the bass panel when run like that is similar or not too much less than when the speakers are run full range, which is handy. Might not need a sub so much like that with a bigger model.
Can use a Pllxo too which is cheap and sounds good.
I've read your comments with interest on this ... when you've referenced crossovers you're referring to analog not digital implementations, correct?
with regards,
Yes either will work. Digital XO like a minidsp etc or an analogue active XO, or a PLLXO (passive line level XO) which in this case (as it's just a first order high pass required) is just a small line level cap in between pre and power amp. The Pllxo would be my preference as you can use a polypropylene or polystyrene film cap. Very good sound and cheap compared to an active XO that would be comparable.
I bumped into a line level Xover aficionado on high eff. a few days back
never tried them myself
thanks!
regards,
Welcome. Did that guy mean the passive line level type (PLLXO)? I played with these quite a bit a few years ago. They can be very good for cheap money.
One problem I found when biamping the older Maggie MGIIIas and 3.3Rs (which require a 3rd order low pass on the bass) is that when using an HP PLLXO, you can get phase matching issues if you are using a digital crossover for the low pass as digital XOs have a delay. The high pass comes in just before the low pass, although you can phase match it up a bit better by playing with the delay on the digital XO. Although I never tried it (but want to) using a 3rd order Active XO with opamps like a Marchand for the low pass might be much better than a digital XO as there is miniscule delay I believe. You can't easily use a 3rd order low pass PLLXO to complement the high pass PLLXO as there is too much insertion loss with 3rd order.
With the current *.7 Maggies (for biamping) I would assume it would be ok to use a PLLXO for the low pass too (as the speakers use all first order slopes), and you could then adjust the level balance with a pot on the high pass.
he stressed that PLLXO was the 'clear' winner of crossovers, money no object
unless I read him wrong
all I could respond with was that I miss tone controls, which totally misses the point of course ... as it turns out some find my sparkling wit rather dull, knuckle dragging troglodyte that I am
<> ¯\_(ツ)_/¯ <>
with regards,
Haha. I miss tone controls sometimes too :-)
I used to use Wima FKP1 caps (film and foil polypropylene) for the high pass PLLXO. Cost about $3 each and sounded v good. More exotic cap options would have improved things more.
I never got as good sound as a PLLXO when using an active XO or digital XO on the high pass instead.
No, either way (analog or digital) can work.
Dave.
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