Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
75.54.226.78
I am currently running a pair of Magnepan IIIas with a pair of Carver M 1.0-t amps in bridged mode for 1000 Watts to each speaker. Do you think if I purchased an ART 311 active crossover to biamp the Maggies that it would make a difference? Biamping would bring the Carvers back to 500 Watts in stereo mode. Any thoughts would be appreciated before buying a crossover that may or may not make a difference.
Follow Ups:
On the suggestion of the good Mr. andyr, I am waiting on the First Watt B4 which is Pass's new inexpensive electronic XO. I could not afford the XVR-1 which seems like a great unit. First Watt also has other devices in their "B" series that would help in a biamp application and you may want to check them out.
I have an MG III which I am upgrading, but in the process I picked up some demo 3.6's. I have tried in full range mode and passive high level biamp mode (as I await the B4). I much prefer the biamp mode.
The long awaited First Watt B4 is shipping, here is the link to the PDF Manual
http://www.firstwatt.com/pdf/prod_b4_man.pdf
Russ
Ideally, you will have a Marchand XM44 with original or tweaked XO parameters. Better yet, if you are willing to do some work on it, you can develop a line level passive XO (PLLXO)- which is much purer in sound, while using a commercial XO for bass low pass. I suggest an Ashly XR1001 for this since it can be adjusted to have a lower Q than the steep standard 4th order XO. Davy with a little help from Neolith and me worked out a PLLXO for 3.x models.
That said, for "quick and dirty" results, there is a significant improvement to be had just sticking in any decent commercial LR4 crossover. The Rane and Ashly models are best, the Ashly is more flexible. But if you insist on going cheap, then the Behringer XO is better for home use and costs the same or less than the cheapo ones.
You can also use DSP based crossovers, cheap ones are available from Behringer (which can be upgraded to audiophile level by Tweakaudio, cullen circuits, and Endler Audio). Then there is the BSS 360 and 366. Others are the Ashley Protea, and the higher end dbx units. There are audiophile DSP XOs from DEQX and Lingdorf (sp?) as well as the mini DSP.
Biamping is not as simple as plugging two amps into some crossover unit. I have always biamped my Maggies going back to 1980 and have learned a lot in the process. Besides close attention to the gain of the amps, it is important to get the correct crossover point and filter order and slope. Most commercial units such as Art, Rane or Behringer are designed for music bands (pro) not home systems and don't give you the flexibility that you need. IMO the active XO should simulate the OEM passive crossover. After all, Magnepan (as do most speaker manufacturers) spends considerable time getting their XO's right before going to the expense of bringing out a new speaker. As AndyR says you need either to buy a Marchand XM-44 and specify the exact crossover parameters that you want or go DIY. Both will work but DIY is about 1/10th the cost. I should add other choices are a DSP unit or a computer set up, neither of which I have any experience.BTW if you are interested in going DIY or with the Marchand XM-44, I can give you the component values to simulate the OEM XO. I currently have my IIIa's biamped with the Marchand.
On the violin: "Heaven reward the man who first hit on the idea of sawing the innards of a cat with the tail of horse."
Edits: 02/10/12 02/10/12
"Biamping is not as simple as plugging two amps into some crossover unit. I have always biamped my Maggies going back to 1980 and have learned a lot in the process. Besides close attention to the gain of the amps, it is important to get the correct crossover point and filter order and slope."
Then you might/should also know that this is exactly what Magnepan/Audio Research Corp did back in the days of the Tympani 1C (and Tympani IIIA). ARC marketed a EC2/a two-way tubed cross-over (frequency set at 1000 Hz, IIRC)for use with the Tympani 1C and EC4a three way for the Tympani IIIA. DIYers could change the X-O frequencies with the right parts and a soldering gun.
Importantly, it sounded perfectly fine.
My first listening to Magnepan's were Tympani I-D's that were driven with ARC amps and the EC-4a. It was an epiphany and I went out the next week and got my first Maggies (SMG's). I kept them for about 6 months and then got Ia's. As soon as the IIb's hit the market, I traded up and began biamping. That was 1980 or '81.
On the violin: "Heaven reward the man who first hit on the idea of sawing the innards of a cat with the tail of horse."
The Magnepan Specification page indicates that the 1D was introduced in 1980. That about conicides with the time ARC went to their 'analog module' components and claiming they would never again ever manufacture tube equipment. I'm curious as to which ARC amp was use to drive the IDs you listened to. Was the ARC D-79 (tube) amp (http://www.arcdb.ws/D79/D79.html still availablefor purchase at that time? I don't think any ARC tubed amp at that time had the necessary current to adequately drive the 4-ohmed Tympani 1D (and my D76As certainly did not.)
You may want to read this thread before considering the MINIDSP route.
http://www.audiocircle.com/index.php?topic=93469.0
At this rate, I may just stay with my bridged amps each powering one speaker.
Take my post above in mind. You can get started with a simple commercial crossover, once you learn what is going on you can proceed further with a simple PLLXO, it is very simple. If and when you want to do something more complex with a DSP unit, get one that can actually do audiophile quality output.
I know this has been discussed before, but I did not pay much attention because I don't see any issues as far as gains. It seems to me that the level adjustment on the crossover is a gain adjustment. It that's correct, then you adjust it to match the gains of the high and low amps and nothing else to be concerned with as far as gain. Am I missing something? I'm enjoying my sound.
Basically, correct. Most units have gain controls to compensate when the amps have different gains. If you don't compensate then the balance of the amps will vary as you alter the input signal strength from the preamp.
Gain is not the same as sensitivity but the two are related and has nothing to do with the wpc. A lot of manufacturers report sensivity but may not specify gain. G = 20*log(Vo/Vi). Vo can be calculated from the power rating (maxium output before clipping) using P=IE and Ohm's law E=IR (or I=E/R) as SQRT(P*R) and Vi is the sensitivity, invariably reported at 8 ohms.
Since manufacturers often "cheat" when they report maximum power, the gains may still need some adjustment even if you have calculated the amps to have the same gain.
On the violin: "Heaven reward the man who first hit on the idea of sawing the innards of a cat with the tail of horse."
Edits: 02/11/12
After doing a bit more reading, I may go the MiniDSP route. Looks like it will do the correct crossover slopes, etc. I am just not sure how much of a benefit I will realize vs. when I tried using the biamp feature of my Pioneer Elite AV receiver. It has the capability to split the signal and create a flat response using the built-in mike. But I am assuming the crossover slopes and pts. the Pioneer is using aren't the factory specs that Magnepan recommends with my IIIas and that is the reason why I didn't hear any benefits.
Unfortunately Magnepan's suggestion of a 3rd order LP at 300 Hz and 2nd order at 500 Hz does not produce the same result as the OEM speaker level XO. I was not pleased with those value and went to a symmetric L-R at 400 Hz, and then 340 Hz. I then designed a custom crossover that simulates the original and had Phil Marchand send me the boards -- success.
On the violin: "Heaven reward the man who first hit on the idea of sawing the innards of a cat with the tail of horse."
Everyone,
Thanks for your thoughts and feedback. I am already pretty happy with the way my system sounds with a Carver amp powering each Maggie. I just wasn't sure if I could use any old crossover. I didn't have very good luck using my Pioneer Elite receiver's biamp option. Didn't seem to do much. But realize now this is passive biamping and not true active biamping.
I also have IIIas and a Pioneer Elite receiver, and was using Carver amps because the Pio isn't rated for 4 ohms. The built-in EQ program never worked well w/ the Maggies--maybe the reflections confused it.
I ran a single M-1.5t, tried a single M-4.0t, and actively biamped w/ the 4.0 on top and the 1.5 on bass. I never considered bridging because the speakers are already a 4-ohm load (not even sure you can bridge a 1.5, but I do have another one). Biamping is by far the best of the three.
Reflecting on the succession, the 1.5 was maybe a little grainy, the 4.0 more musical and more forward but the bass wasn't as tight. For biamping I use a Pass XVR-1 and duplicated the factory slopes. With biamping I got more headroom, the smoothness of the 4.0 and the tight bass of the 1.5 (but even better than the 1.5 alone). Clarity and detail improved, imaging sharpened, and the soundstage opened. How much of the improvements would have come from just upgrading the Maggie external XO components is unknown. At some point I swapped in a recapped 1.5, which also helped the bass, and added tweeter chokes which reduced grain.
The Carvers were recently replaced w/ a Sunfire Sig II, and there's one channel left over for a Maggie center. More detail and better bass control, and the music just sounds more live. If things ever settle down I'll take some measurements.
BTW, how did you achieve passive biamping? At least on my VSX-92tsh, Front Biamp hides the graphic eq option for the rear surrounds, so you can't even try to use the built-in eq to rig a (really) crude XO. Did you open up the external XO box and split the high- and low-pass, with one channel to each?
Dave
--it's close enough for jazz...
Dave my Pioneer Elite in biamp mode has the capability to adjust the eq. I agree the Pioneer is probably being tricked by the nature of how Magnepans are designed.
you need to use something other than the ART 311 active crossover. You need one which will be able to give you asymmetric slopes - eg 18dB bass LP combined with 6 or 12dB mid HP. It is also nice to have the ability to finely adjust the -3dB "knee" frequency ... a knob that gives you, say 200Hz, 300Hz and 400Hz is not going to be good enough.
Something like a Marchand XM44 would be a good choice, if you are not into DIY (you get different plug-in modules from Phil M for each slope/frequ you want).
Or you buy a sophisticated digital unit like one of the DEQXs (which also offers phase correction and room correction).
Regards,
Andy
Bi Amping with an active crossover is much better then biamping with the stock passive crossover. Your amps will have more headroom and better damping control of the maggie panels.
Look into the minidsp for active crossover duties. I am really enjoying my minidsp with my maggie 1.6's. It is very inexpensive for the power you are getting.
read here-
http://www.audioasylum.com/cgi/vt.mpl?f=mug&m=184970
Well. I do not think it will be an upgrade... First, the crossover slopes of the IIIa are different for the low- and high-pass legs (18 dB and 12 dB/octave). I would advice to use similar slopes for an active filter. Second, the ART crossover does not seem to be a candidate for sound quality. Lot of potentiometers and switches in there that have will degrade the sound. Something simpler and purer would be better. Unfortunately, they are rare and you will probably have to build yourself or let someone do it for you.
A good start would be reading this:
http://www.integracoustics.com/MUG/MUG/tweaks/AndyR/
Roger Gustavsson
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: