What should I upgrade?

Is it possible to bridge my s300 so it outputs 600w and buy another s300 to bridge? If so, how does one "bridge" an amp?

Hi Devon,

No, a fully balanced stereo amplifier such as yours can in a sense be thought of as being two amplifiers on a single chassis, each of which is already bridged. By that I mean that each channel contains two amplifiers, one of which amplifies a signal that is inverted in phase relative to the signal being processed by the other amplifier, with the speaker being connected between the "hot" outputs of the two amplifiers. That results in twice as much voltage appearing across the speaker, relative to what a single-ended (unbalanced) amplifier with otherwise identical characteristics would provide.

So bridging a single speaker between one of the output terminals of one channel and one of the output terminals of the other channel, with the inputs to the two channels wired out-of-phase relative to each other, would not result in any added power capability.

Also, fyi, bridging results in the amplifier seeing the speaker impedance divided by two, so your nominally 4 ohm speakers would be seen as 2 ohms, which many amplifiers cannot handle. A major reason that Bel Canto specifies a 4 ohm minimum speaker impedance for your amplifier figures to be that the factor of 2 applies in the case of fully balanced operation as well.

Regards,
-- Al

Devon -- Some fundamental questions which I don't think have been addressed so far:

1)How far is your usual listening position from the speakers?
2)How far are the speakers from the wall behind them?
3)How far apart are the speakers?
4)What is the distance from each speaker to the nearest sidewall?

Regards,
-- Al

Hi Devon,

As we've seen, a case can be made for many different approaches. But here is my take, and I'll qualify it by saying that my experience with Maggies is fairly limited (several listening sessions at a friend's house, to one of the older, larger Maggies driven by Audio Research tube electronics, and integrated fairly successfully with a Sunfire subwoofer).

Your 8 to 12 foot listening distance leaves me much less inclined to recommend higher amplifier power than I was initially (based initially on the size of the room and the relative inefficiency of the speakers). And consider too that the upgrade you were initially asking about, from 300W to 500W, is only an increase of a little over 2db. I think that the clincher (in terms of not upgrading the amplifier power, at least for now) would be if you are satisfied with the volume you can achieve in the mid-range frequencies.

I think that a significant contributor to the bass shortcomings you are sensing is likely to be the 3 to 5 foot distance to the wall behind the speakers. That will result in a partial cancellation of bass frequencies centered in the area of roughly 70Hz. (The approximate formula is 86Hz divided by the distance to the wall in meters, and the effect is known as "1/4 wave cancellation"). That occurs because the reflection of the sounds at and around that frequency, that are radiated towards that wall by the speakers, will re-arrive at the speakers approximately 180 degrees out of phase (i.e., inverted) with respect to the original wavelaunch, and will therefore subtract from the original wavelaunch at and around that frequency.

Fixing problems in the deep bass region via room treatments is problematical at best, because the long wavelength of those frequencies makes them difficult to absorb. Moving the speakers further from that wall, if possible, would certainly help though, by lowering the frequencies which would be affected. So I would suggest trying that first, if it is practical to do so. Doubling the distance would get most of the affected frequencies below the speaker's 3db bandwidth point, which I feel pretty certain would produce a significant improvement.

If it is not practical to do so, or if doing so does not result in adequate improvement, considering that you undoubtedly have significant attenuation centered around 70Hz due to room effects, and considering that the speakers themselves are specified to be down as much as 3db at 40Hz, my strong instinct would be to add a subwoofer (or two). I would consider things like optimizing cable selection to fall within the realm of fine tuning the system, but I think that the issues I've mentioned are more fundamental and need to be dealt with first.

Regards,
-- Al