Soundlab speakers with sub woofers?


Hello, I'm looking for input from folks that have used Soundlab speakers or electrostat speakers with sub woofers. It's thought that the sub woofer needs to be quick in order to keep up with the speed of the panel and integrate seamlessly. Has anyone found a subwoofer(s)that was fast enough to work with an electrostat panel and more specifically Soundlab electrostats? What model of subwoofer worked well and how was the subwoofer integrated into the system?
128x128keithmundy
Hi Bob, You got it almost completely right in your last paragraph- right up to the last sentence... so, you said

The power dissipated by the speaker will fluctuate throughout the audio band inversely proportional to the impedance.

Which is correct. Now all you have to do is understand that the efficiency of the speaker does not also change- it is the nearly the same at all frequencies.

The Sound Lab has an impedance curve that varies by about 10:1 from bass to ultrasonic (30 ohms down to 3 ohms or less). So if the amp makes more power than it should in the highs and less than it should in the bass, it can't help but to impart a coloration.
Understanding your speakers will help when you try to tune subwoofers, whatever the brand, to aid the bass.

The Soundlabs, as well as any other stat or dipole that runs down into the bass, will exhibit reinforcement at some frequencies (constructive interference), cancellation at other frequencies (destructive interference), phase shift (various degrees at all lower frequencies), and there is absolutely no way around those realities of physics. Folks are prone to saying "but oh, you have to hear my system, I have no problems" but that is simply wishful thinking. As long as folks will tend to define themselves by their possessions the "mine is perfect" syndrome will rear its ugly head. But the compromises, fairly big ones, are there at the lower frequencies.

Most folks don't want to use a high pass filter on such a large speaker that is capable of low frequency output(and this is the fatal trap, the ability of putting out low frequency energy, lulling folks into wanting to use it, but this is different than putting out relatively flat, somewhat low distortion low frequencies, which no full range stat can do) but blending will be more difficult if one lets the Soundlab run down low. No matter what the sub, it cannot track the uneven bass of a stat and fill in where needed. Most folks have blamed subs for being "slow" when problems arise when blending a sub, but in reality even a perfect sub will make the problem worse when it is overlapping in frequency coverage with the stats.

By the way, there is no "slow" sub and no "fast" sub. The erroneous terms "fast" and "slow" have arisen when folks have tried to describe the sound of subs that have low ("fast" sounding) or high ("slow sounding) harmonic distortion, or when a low distortion sub overlaps the frequency range of a monitor speaker, creating excess bass at certain freguencies.

If you do not want to put a high pass crossover in front of the Soundlabs you do have an uphill battle. That is not to say that you cannot achieve better results than you have now, but there will be no "MAGIC BULLET". Your best bet will be to obtain the lowest distortion sub you can that also has a variable crossover point as well as the ability to change the low pass slope.

The JL models previously mentioned are an example of good subs that have good adjustability. But they do not come with a high pass crossover for your speakers, should you want to try that route. They do have a new crossover that is sold separately but I cannot speak first hand of the quality.

Remember, it is not possible to beat physics, and if it were there would have been plenty of full range panel speakers with great bass over the years. The Martin Logan CLS, the Apogees, the Soundlabs, and we could go on and on, all had their problems in the bass. The only stats that don't have real, apparent non-linearities in the bass are those that have little bass to begin with so the problems are not as easily noticed. Those are also the ones that are easiest to blend subs with....and it sound here like I am advocating a simple high pass filter on Soundlabs. I am, despite the seeming paradox of having a big speaker and not using the bass from it.

Mrmb heard the MA-1s and MA-2s here on the U-1PXs several months ago in our large custom designed, acoustically symmetric room. Since that time the speaker positioning has been improved, yielding better imaging and mid bass, along with a significant evolutionary improvement in the DAC he heard.

Brian Walsh
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Bob, part of the disconnect here between you and Ralph is due to terminology. Including:

1)Strictly speaking, speaker efficiency refers to acoustic power out vs. electrical power in. It is also commonly used to refer to SPL at a given distance vs. electrical power in. SPL vs. voltage in is sensitivity, not efficiency.

2)When Ralph says that an amp "makes power," he is referring to how much power the amp delivers to the speaker.

3)When Ralph says that a Sound Lab is driven by power, not voltage, he is asserting that for the speaker to produce flat frequency response in its acoustic output, it must receive electrical power (not voltage) at its input that either is or approximates or approaches being flat as a function of frequency.

As you realize, given the huge decrease in the speaker's impedance between the bass region and the upper treble region, no. 3 can only occur if the voltage at the amplifier output terminals/speaker input terminals is NOT flat as a function of frequency.

Also as you realize, nearly all solid state amps will produce output voltages into varying load impedances that are essentially flat as a function of frequency, as long as the amp is operated within the limits of its maximum voltage, current, power, and thermal capabilities.

While on the other hand the interaction of the output impedance of a tube amp and the variation of a speaker's impedance as a function of frequency will result in nearly all tube amps coming at least a little bit closer to supplying power (not voltage) into a varying load that is flat as a function of frequency, when the amp is operated within its capabilities.

Also, the MAXIMUM power capability of a solid state amp into high impedances can generally be expected to decrease in close proportion to the impedance rise above 8 ohms. While that decrease will usually occur to a considerably lesser extent with tube amps, and an increase may actually occur with some amps over some range of impedance increase. Ralph is correct that a solid state amp rated at 600 watts into 8 ohms will generally be able to deliver only about 150 watts into 32 ohms.

Best regards,
-- Al