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In Reply to: RE: 800 W/ch for maggie 20.1 posted by dromney on August 28, 2016 at 13:57:01
I suggest you will get an additional increase in SQ from putting your 2 Macs back into stereo mode and replacing the external passive bass/mid XO with an active XO. Something like a Marchand, if you want an analogue XO ... but I would recommend a miniDSP 10x10Hd unit (which I have just bought to replace my 3-way analogue active XOs) as it gives you DSP to correct room-mode nodes as well as the bass LP/mid HP XO. It will allow you to go 3-way active in the future, if you decide you want to do this, and offers the luxury of having 4 different confg setups loaded that you can flip between, on the fly. :-))
Regards,
Andy
Follow Ups:
I think dromney will benefit from taking out the 20.1 speaker level crossover and replacing it with a line level XO, That would decrease the power loss on bass due to the crossover and may allow the use of a single mac channel for bass vs. the two of them bridged without a loss in bass control dynamics and tightness. Where the benefit would be is that the upper amp on the mid/tweeter would not see anywhere near as much stress without having to drive the bass, so would have better clarity and imaging.
I am not going to suggest the use of a DSP XO universally. If you are not doing high rez digital and vinyl then the DSP is fine. If you are sensitive to the kind of timing and phase issues that an AD/DA loop introduces even at 24.96 then you will want to stick with analog crossovers. I am one of those that are bothered by AD/DA loops. Before committing to a DSP you need to find out if you are one of the people who would be negatively affected in this way.
I am also bothered by high order crossovers, and have gone to extremes to get rid of them since they introduce some of the same time domain and phase issues that bother me with digital. The higher order XOs in the pre .7 series maggies were a bother for me so I eventually took out the high order XO when I had the Neo8 midrange installed and tried it out without a crossover - just playing on its own full range. I now use it either with a standard linear phase/1st order XO or just use it with a high pass an octave below its acoustic rolloff so that it has virtually no phase through its entire output range. It does not have a LP and the tweeter is phased in with a 1st order HP in the top octave as in the ET LFT8 and some Apogee models. With that you have a rather clear window to hear what AD DA loops take away. And so far I have not had good enough results even with more recent 24/192 AD DA which also revealed themselves on the Focal Nova Utopia. I disliked the straight AD DA so much that I could not assess the benefit of the DSP that is the point of the processor. Whatever good it could do was swamped by the initial AD DA performance. .
I am a little curious about bi-amping, which would require active cross-overs. I am not that interested in a digital cross-over, simply because I don't want to transition again analog to digital to analog and the artifacts that come along with that. Bi-amping may or may not improve the sound I currently have. That is one nice thing about have this much power available so that the amps are not stressed even when putting out a lot of bass. The upper range stays very clear. I am pretty happy with the factory cross-over (which I have heard is better than the 20.7s). However, I would like to hear it for myself.
I don't think you need to work hard on the subject of biamping. So far I have found one person to have preferred single amping a maggie. But then he hand tweaked the passive crossover to taste over years. The execution is easy enough once you have the amps at hand. As for the line level XO choices you can get
1. an AR crossover designed for maggies and give them the model and send it in for a checkup and to put in the appropriate components for your model's XO It has an active low pass for bass and a passive high pass for mid/tweeter
2. use a First Watt B4 crossover for max flexibility in choosing both freq and slope,
3. Have Marchand build you an XM 44 with the right crossover to emulate the OEM crossover
4. Do a DIY passive high pass and active 3rd order low pass - or just get a used 3rd order vintage 3rd order XO from Ashly Furman Pioneer Sony Yamaha Accuphase etc.
5. If your budget reaches that far the Pass XVR1 crossover will do an excellent job.
Satie, I am going to look into it. When bi-amping I would use one amp for the bass (one channel for each speaker) and one amp for the mid and highs, correct? It seems that for a single amp dedicated to a channel I would have the majority of the 800W available to support the bass panels on each speaker, and if I bi-amped, I would then be limiting myself to 400W/speaker bass panel? I must not be understanding something about how to apply this, as this seems to actually limit head room.
That is entirely correct. However, you should have the top amp loafing in its best performance where you will find more clarity than you imagined possible. While the bass amp will be often driven to the end of its tether and will be producing some distortion - but the bass panels produce quite a bit of it themselves at the bottom octave - 25-30% at high volume 30-40 hz has been measured. So you don't really care about the bass amp being stretched. The main downside is that it might sag on very low freq loud material and provide woolly bass. in which case you can easily flip the extra Mac for a higher output bass amp - where you don't care about its refinement in the midrange etc..The large Emotiva, XPA and quite a few Pro Audio and Audiophile high power pieces can fill the slot. I use a fan cooled linear Crown 5002VZ for my bass panels. I have clipped everything else including a parallel strapped Classe DR 9 (rated 400W but measured 600), Bryston 4B NRB bridged and stereo.
With all the progression I took with my system I can tell you that active bi-amping made the most difference. I stayed analog using a Marchand XM44. I will say I'm not an engineering expert like a lot of you here are (and I want to say thanks for all of your expertise) I don't measure any thing or make any sort of measurements. I solely fly by the seat of my ears.
With that said I had friends of friends over that were audio experts one of wich had a 200K + system with Magico speakers and he was totally in awe.
Yep.
I am surprised after all these years there is still so much trepidation regarding bi-amping setups. It's an inherently superior scheme with no down-side and considerable up-side. DSP schemes have a different set of trade-offs than analog schemes, but either is superior to the alternative.
Audiophiles are some of the most hard-headed and resistant to traditional paradigm thinking people I've ever seen. :)
Line-level crossover systems with direct-connected bandwidth-limited power amplifier setups have been used for decades. The folks in the pro-audio world have understood the benefits for decades as well.
Oh well.
Dave.
nt
Andy,
I seem to remember reading some criticism of the mini-DSP when they first came out in that they were noisy. I assume that you have not had this problem - would you care to comment?
I married the perfect woman. The downside is everything that goes wrong is my fault.
Hi Neo,
"Noise" from a miniDSP can be either:
#1: hiss from the speakers ... like 'tube rush', say.
#2. or you get an almighty thump through the speakers if you turn it on or off ... and your power amps are on.
I certainly have absolutely none of #1. In fact, I find it hard to make out any degradation from my vinyl now going through a digital device.
I also don't get #2 with my miniDSP 10x10Hd - although earlier miniDSP 2x4 units were notorious for making a thump when they were turned on or off - so you had to be careful to switch off your power amps first. (They have now fixed this problem.)
Regards,
Andy
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