Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
152.135.148.124
Hello all,I'm considering passively bi-amping my Maggie 1.6s.
I have a Sunfire amp that I plan to use for the bass panels, and I'm considering getting another amp for the mids/tweeters.
What should I look for in the 2nd amp to match well with the Sunfire.
i.e.: Gain, power, etc. Room is 12' x 13' x 9'hi.
Also - If you're bi-amping, what amps are you using?
I did a search and read a lot of posts, but they're pretty much all over the place on similar but not quite the same questions. Thought I could get some help.
Thanks,
Mike
Follow Ups:
In this thread, folks have alluded that there may be no, or little, benefit to bi-amping when using the stock passive xover. Well, after about a year of running four CJ Premier 12 monoblocks, one into each of the four individual panels of my 1.6s, I feel that this doesn't sound better than using just two amplifiers. In fact, it may not sound as good. To me, the net is all downside - no sonic improvement, burning more tubes, burning more electricity, pumping out more heat, requiring more expensive amplifiers that take up more space, and requiring more cabling.
And 140w into each panel is just overkill, I think. Talk about first watt. With a RatShack analog SPL meter, from my listening position I typically listen at average levels of about 85dB, with peaks into the low 90dB range. The amps have it pretty easy.Now, I was just plugging amplifiers into the stock 1.6s. No mods, no active xovers. And, as it turns out, I'm using my pair of old, updated CJ MV-75s in a similar fashion to the way I was using the four Prem 12s. Each of these set ups provides four channels of amplification. With the MV-75s, I have four channels of 75w each, rather than the four channels of 140w I had with the Prem 12s. I can also run the MV-75s as 150w'ish monos. Either way I run them, the MV-75s are more than enough power for the 1.6s. The MV-75s sound different than the Prem 12s, but both provide more than enough power.
This can be a fun journey. you're working with a pretty small room, relatively speaking. So I don't think you need tons of power for your second amp. You'll find lots of discussion about matching the amps and all, but let your ears be your guide. Some claim to hear discontinuity between amps that are not matched. others claim that it is best to have an amp optimized to the task -- delicate and accurate for the treble, and strong/powerful and rhythmiccally solid for the bass panels.My experience was that I preferred the sound with tube amplification. That meant getting a strong tube amp for the bass panel and another less strong one for the tweeter panel. I worked with Davey (Dave Reit) who helped me design and build my crossover based on the Linkwitz Labs MT1 board. This is a cheap and good way to get active crossovers that exactly match the stock internal X/O in characteristics.
The only scary part was lifting the socks on the Maggies to attach new hookup wires directly to the speaker elements. Some put in Cardas or other high quality speaker terminals, while others bypass everything and hook the drivers directly to the amps (bypassing the fuse too). This is what I did.
The end result of this was a spectacular improvement in sound. I've no intention of reverting to stock, although I left my crossovers in place so I could easily return to stock in case I want to sell the speakers sometime. Little chance of that. I'm too happy with the result.
By the way, I recently got Mye stands myself. That too gets a rave review.
Just drop a line if you'd like specifics or help or advice
on my MMG's, I've used the MCintosh 2205 in HP or LP applications, my Tube Dyna in the HP, Dyna 400 in the LP. NAD 2150 anywhere, the Amp section of my HK520 rcvr has been in either/both sections as well. Depending on the crossover - gain matching is level to the attenuators (level controls) at the xover output or amplifier input. I have a home made analog xover, and a older Rane Analog - but I'm using the Behringer Ultra drive now in the system because of the eq. I had to use a little + high treble with the dyna, the other amp combos needed a sloping down signal. I like the Behringer also because I can remove or add a "presence dip" eq (.6Q centered at 3KHz) with just a few button presses. Some recordings seem to already have it, others sound better with it.I liked the sound of the tube HP best - but after eq they all sound pretty good.
Hi Mike,The spec sheet says the crossover is at 600Hz. You haven't specified how many wpc into 4 ohms the Sunfire is, so it's hard to give you a specific recommendation for power required for the mid/tweeter amp. Not less than 75% of the Sunfire, I would say.
The most important thing is that the amp should have about the same gain as the Sunfire ... otherwise you get a mismatch on the volume level of each driver. Yes the best situation is to have EXACTLY the same gain (which is what I have with my IIIa 3-way active setup) but if, say, the Sunfire had a gain of x30 then anything from 28-32 would do for the other amp.
You will get a better sound out of the 1.6s if you actively bi-amp ... and then you would normally have a band gain control with this, which means that amp gain mismatches can be corrected.
Regards,
Use smaller, sweeter (tube?)amp for tweeter panels, temporarily install pot on bass amp, replace with appropriate resistor when system is dialed in. Or....
Buy another amp exactly the same as the existing, and vertical bi-amp.
Thanks, Andy.
The Sunfire is 325/650 wpc into 8/4 ohms.
There's no spec I can see for gain. However:
Max Output Voltage=51Vrms
Input Sensitivity for Rated Output=1.8Vrms
Does this mean that gain = 51/1.8 = 28.3? Hey, I'm just guessing here.
But - Now you've got me thinking about active crossovers, but I think I'll do a little research and post later if I can't figure it out.
I'm also looking at Mye Stands...So many choices, I don't know what my next move will be.
Thanks for the help.
Hi Mike,Yeah, your maths sound about right! I seem to remember my AKSA amps are about the same gain.
Yes, Mye stands - or similar - are a must, IMO.
Read the articles here about active XOs:
http://sound.westhost.com/articles.htmI use Rod's active XO but he only sells the PCBs & instructions ... ya have to do all the work yourself! :-))
Marchand sells active XOs but they also sell the finished product, as well as kits.
Regards,
The calculation is 20*log(Vout/Vin). It's just a coincidence that the value of Vout/Vin is close to the actual value (29.0). It's rare that the max output voltage is specified -- usually you have to calculate it from the rate output at a given impedance where Vout = SQRT(watts*ohms).
IMHO passively biamping is a waste of time because you have the cruddy stock crossover and even if you upgrade the components you still have insertion losses and Rg (all the resistance in the crossover not attributible to the driver) messing up the dampening factor of your amp.
I may be an egoist but at least I don't talk about other people.
As you know, I agree that active is certainly better than passive but I think SOME benefit can be had from passive bi-amping ... as long as you replace the Magnepan stock components with good ones! :-))Regards,
This post is made possible by the generous support of people like you and our sponsors: