Is it best to use a 5-channel amp for biamping??

My next amp will be a sunfire (not the signature series). Please advice if buying the 5-channel cinema grand and use its channels in a bi-amp configuration will give me better results as opposed to just getting the two channel stereo amp?

Thanks in advance
If you're asking whether bi-amping (active x-over, or passive line-level xover) a pair of speakers is better than driving them in passive form -- you bet.

If I understand the question: you're considering a 5channel amp in order to use 4 of these channel to bi-amp your speakers?? If so, great -- but can you disconnect the speakers' existing x-over and devise another one to precede the amps???
Greg is right on the money. Increasing power potential is always a great thing, but if you can shorten the signal path between the amp and the speakers by removing passive components in the crossover, that will get you even better results. While this would also require some type of crossover between the preamp and amp, the benefits of this type of installation have to be heard to be believed. Sean
But I think he's asking if he can just split the signal into 2 channels to drive a single speaker in bi-wire fashion without doing everything descriobed above to the crossovers...I am curious about this myself.
I meant could he split the signal and use 2 channels to drive a single speaker in bi-amp fashion, sorry.
If a speaker requires that all four binding posts be hooked up in order for all of the drivers to operate properly, one can passively bi-amp with out a problem. There is one hitch to this though...

If the speakers are improperly wired internally AND someone is using two different amps to run their speakers, you could run into big problems.

The reason that i mention this is that this is the exact situation that we ran into with my Father's speakers when we pulled them apart. The lower midrange driver was "cross-wired". In other words, the positive of the midrange was connected to the "high end" binding posts and the negative of the midrange was connected to the "low end" binding posts. Luckily, my Father never tried bi-amping his speakers.

What this would have done is tied the output stages of each amp together electrically. Depending on the design of the amps and the voltages involved, this could result in "smoke". While this was obviously a mistake from the factory, it would have been a costly one for the consumer. In such a situation, i can picture someone standing there with one wire in each hand and blackened soot all over their face saying "what the hell happened???".

In this type of situation, i sincerely doubt that the manufacturer of the speakers wouldn't have stood behind their mistake and paid for the repair of one or both amps. The really bad part is that someone might have the amps repaired and not realize that it was a problem with the speakers, possibly repeating such a disaster.

As such, i would suggest connecting just the high frequency section of the speakers in normal fashion and make sure that all the drivers work as they should. When your sure that this works fine, connect the low frequency section and make sure that all of the drivers used in that frequency range are working okay. Once you've done that, hook the positive to the high end section and the negative to the low end section. You should have silence. If it is silent, connect the negative to the high end section and the positive to the low end section. That too should be silent. If you get sound out of either of these "non-standard" wiring configurations, the speaker has internal wiring problems or is not a "true" bi-wire / bi-amp capable design. Sean
but you can bi-amp off the different channels of a multi-channel, assuming what you described as a possible issue does not exist?
Thanks everyone for your response. I think Arthursmuck understand what I am trying to do. I am sorry I did not mention what speakers I want to biamp. I have the ML SL3, which are design for bi-amping.

I am trying to decide which Sunfire amp I should get:
The 5-channel cinema grand or the 300W two channel.

It seems to me that I might get more out of my SL3 if I use the 4 channels of the Sunfire cinema grand in a bi-amp configuration (two channels per speaker). Has anyone use a 5-channel amp to biamping this way?

I hate to say that anything is an absolute as there are almost always exceptions to every rule. With that in mind, it would be pretty safe to assume that you should be "okay" even with goofy internal wiring in the speaker so long as you were running multiple channels from the same amp. There are some amp designs that i can think of this causing problems with, but none of the multi-channels that i know of use this approach.

As a side note, i did this for a while when the two channel amp that i use for the mains in my HT system was sent back to the manufacturer for inspection and upgrades. I had another 5 channel amp that i wasn't using, so i ran four of its' channels to passively bi-amp the mains with. Since it was from the same manufacturer, there wasn't a drastic change in sonics either way. Sean
so Sean are you saying it's possible that using 2 of the 5 channels off the same amp to bi-amp will not deliver sonically noticeable results due to the channels all being the same maker, sonic signature, etc?
No, no, Arthur-- you'll use FOUR of those channels to bi-amp: one channel for the right woof, another for the left woof, another for the right mid-hi's and another for the left mid-hi's. Total, four.
The difference in sonics comes from driving the speakers' drive units directly, the crossover being behind the amps rather than in front. Cheers

What do you mean by this statement..."The difference in sonics comes from driving the speakers' drive units directly, the crossover being behind the amps rather than in front"?

Are you implying that a 5-channel biamp configuration will be sonically better than a straight 2-channel instal?


Not quite; sorry should have been clearer. A little b/ground first:
Two channel stereo:
your amp receives a full-range signal (i.e. all the frequencies, typically from ~20Hz to ~22kHz) from the pre, amplifies it, and sends it as is to the two speakers, each amp channel providing a signal to one speaker. In turn, the speakers have typically 2-3 drivers on them. Each driver is designed to work best reproducing PART of the full-range signal -- so a cross-over inside the speaker filters OUT (attenuates) certain frequencies and sends the rest to each driver. The result is that the 2-3 drivers, between them, combine to give us the full-range signal that originally left the amp.

NOW, what Sean and I were saying is that, IF you were to filter certain frequencies BEFORE they actually reached the channel of the amp and then connected the amp output DIRECTLY to the driver that works best with said frequencies, the result would be far better because each amplification channel would ONLY be amplifying the frequencies that the driver it's connected to reproduces, i.e., no waste. Also, since woofers eat up most of the energy, you could have one amp channel each for the two woofers (that's two channels) and another channel each for the rest (another two channels). That is active BI-amplification and in our example you need four amp channels to do it, so a 5channel amp is indicated (you even have 1 channel extra).

HOWEVER, if your speakers have a bi-wiring facility (i.e. two pairs of connectors behind each speaker, one mid-hi, one bass) AND these are actually DISCRETELY connected to two separate filters, you can, again use four channels of amplification, each channel connected to each of the speaker inputs (four inputs, two per speaker). BUT, in this case, each amp (a channel is an amp, anyway) would be amplifying the full-range signal part of which, in turn, would be filtered out by the crossover that's inside the speaker -- SO, little improvement (the crossover is a problem-maker!) to be expected usually. Sean also adds that, since it's the same amp (i.e. 4channels of the same amp) you will have the same sonic "signature" all round... if you were to use a different amp for, one of the speakers' sections, then there would be some versatility in roughly choosing the sound you like (soem people like tubes for mid-range, but use ss for the bass region, etc).
Hope this helps!
thanks sean and greg, I've been trying to understand this for sometime, and your explanations have finally made it make sense to me. Sounds to me like I will hold off on bi-amping until I'm ready to add a crossover between the processor and amp. one final question, if I am running N802's, which like high levels of power, would I hear sonic difference running two channels off my amp into each speaker, effectively doubling the power they're receiving? I realize it probably won't be as significant as actively filtering the corssover before the amp, but would it be pronounced given that my speaker respond better to increased power? (my amp is a Krell TAS 200x5)
Thanks for the clarification! I am well versed on crossover /band-pass filters circuitry. I just wasn't clear on the way you used "sonic signature" in this context.

I think I will go for the 5-channel cinema grand, instead of the regular two channel Sunfire.

Thanks again.
I would like to read the response to Arthur's statement regarding the improvement with more power, would like to add a little twist to it.... if your 5 channel amp is struggling to handle the speakers (using one channel per side), so using 2 channels of the 5 for each side (L & R) wouldn't it be expected to have a more noticeable effect (common sense suggest dynamics) with this scenario? Thanks
Increasing power typically results in a more consistent presentation regardless of volume. This translates to maintaining a more cohesive and liquid presentation as spl's are increased rather than the grain, glare and distorton that we experienced when pushing the system with the smaller amp. By removing all of the negative attributes brought about by the limited headroom of the smaller amp, one can listen at higher levels with less fatigue for longer periods of time. That's because you aren't hurting your ears as much due to a reduction in multiple types of distortons. All of this with increased coherency. Then again, going to a bigger amp that lacks proper design and uses lower grade parts may actually sound worse than a lower powered amp that was well built and designed. Quality first, then quantity. Sean
Arthur- IMO using 4 of the Krell's channels should make a difference. I'm assuming the B&W's bass & mid-hi x-overs are discrete (not connected) of course. You should have better control and response in the low frequencies.
Planckscale- sorry for regurgitating what was obvious to you!
Thanks gentlemen!
Don't mention. I appreciate your input.
Let's take the discussion a step further. If I were to split the signal at the amp, and rather than use 2 of the channels on my Krell, use one and run the other side of the split to a tube amp, what type of things would I need to understand in terms of power, crossover, etc., to appropriately match a tube amp to the mid/high connections, and my Krell to the woofer?
But for hybrids like MLs, which Planckscale has, passive biamping has significant advantages.

Passive biamping an ML hybrid separates the stat from the woofer, thus presenting the amps with a less complex load.

The stat panel presents the amp a high impedance at low frequencies and very low impedance (1 to 2 ohms) at high frequencies. The woofer's impedance curve is relatively more flat. Driving them separately makes the amp's job much easier.

I biamp my Aeons with four of the five channels of my Meridian 5-channel amp. This makes the speakers more dynamic - a frequent complaint about hybrids is that they're not dynamic enough.
"I biamp my Aeons with four of the five channels of my Meridian 5-channel amp. This makes the speakers more dynamic - ...."

Case closed! Thanks Jetmphfor
Also, thanks to all for your contributions.
I really appreciate. Through you guys, I have rediscovered music!
I should add that by using your 5-channel amp this way you are, in effect, vertically biamping, which works better for Logans than horizontally biamping. Cheers.
Jetmph: With a Sunfire Cinema Grand, you would be neither vertically or horizontally bi-amping. That's because all of the channels are fed off of one common power supply. If running an amp with a dedicated power supply for each channel, it still wouldn't be vertically or horizontally bi-amping.

Vertical bi-amping implies that one power supply ( or amplifier ) feeds the left speaker while a separate power supply ( or amplifier ) feeds the right speaker. Horizontal bi-amping implies that one power supply ( or amplifier ) feeds the high frequencies of both speakers and a separate power supply ( or amplifier ) feeds the low frequencies of both speakers. Since every section of the speaker is being fed from one common power supply, there is no difference in this case as far as "vertical" or "horizontal" is concerned. So long as the power supply is big enough to feed all channels simultaneously, the biggest difference in performance will be increased dynamic headroom and the reduction of dynamic compression. The sonic results of this should be increased spl capacity and a more cohesive presentation, regardless of volume.

Since the power supply in this amp was designed to feed 5 channels of amplification and only four would be pulling on the power supply, i think that this type of installation with this specific amp should work great. The fact that Planckscale can experiment with the voltage / current outputs for the top end on his ML's is simply icing on the cake. Sean
Jetmph, Sean... keep them coming! I have been contemplating on buying the signature series, but with you inputs so far, it seems the standard Cinema Grand will do just fine in this configuration.

It is interesting to see that everyone here so far thinks that this configuration will work well with the Logans.
It was because of inputs such as these that I was able to buy my first (most probably will be my last) subwoofer - the Bag-End Infrasub-18!

If i was spending the money, i would buy the Signature. Then again, that's me : )

Seriously though, i own both the Signature and non Signature versions of the two and five channel amps. In my HT system, the standard versions worked well but ran out of steam when really throttling the system hard. Bare in mind that they did much better in this regard than some other amps rated for even more power. From there, i went to the Signature versions which gave me more of the headroom that i needed. I will say that there are differences in the sonics between the two channel and the multi-channel and from what my ears tell me, between the Signature and the standard models. In my system, the Signature versions ( both two and five channel ) sounded best.

As to a different point of view, my Dad was running my Sunfire two channel amp for a while with another amp for his center and surrounds. I temporarily brought over my 5 channel Sig and let him run that for a bit while we were getting some other things straightened out with his system. After getting things where i wanted them, i ended up bringing over the standard Cinema Grand and setting him up with that. In his opinion, the standard Cinema Grand was sonically superior to the Signature version. That made me happy, as i thought that the Signature sounded better in my system. As such, we were both happy campers sonically and i didn't have to spend any more money : )

As a side note, the Architectural Series are supposedly slightly beefier than the "full size" versions. This has to do with power supply revisions, etc... Due to the smaller chassis and limited heat dissipation though, they may run slightly hotter.

One thing that i would suggest with ANY Sunfire amp is that you should get some type of solid "cone" type footer underneath them. This elevates the amp off of the support shelf, allowing it to breath better. The "weird" thing about these amps is that they dispurse their heat from the bottom plate, not out of the top or sides. As such, soft footers placed underneath the amp can be damaged from the heat if you stand on the throttle long enough.

I would also suggest a good heavy gauge power cord. Even though these are "high efficiency" amps, they can still pull TONS of current if called upon to do so. If you really want any of these amps to work their best, especially if you have low impedance / low sensitivity speakers, a dedicated 20 amp line is a must.

If buying used, the first or second production run of their amps have permanently mounted cords, all of those produced after that make use of IEC's. While i hate IEC's for their poor connection qualities, they are convenient when it comes to trying various power cords. Sean
Go the the MartinLogan Owners forum and ask for feedback about Sunfire amps. Some are happy; others have issues.
Sean, that was very informative. Do you think the difference between the signature and the standard model is compelling enough to justify spending the extra money? My last amp was an Onkyo Intergra 504, therefore I would think the standard model will be a big upgrade for me.

Jetmph, Interesting site! Thanks.
Planckscale: It is typically cheaper in the long run to plan ahead / think about future moves than to just buy what you can get by with now. If you take that approach, i can pretty much guarantee that you'll end up upgrading later and spending more money doing so. Then again, many of the folks selling the "standard" Sunfire's and Cinema Grand's at reasonable prices are moving up to the Signature versions. Following that path isn't a bad thing ( i did it myself ), but if you've got the money now or can swing the difference in a short period of time, i would hold off and just make one big jump rather than two more costly jumps. Other than that, you can't have "too much" power. That is, unless you're "wreckless" with the volume control : ) Sean

That's what I call "boiling it down" advice!!!!!!
I've been sticking to a lesser amp tweaking the whole system while building the "critical mass" and take the leap!