How Hsu Subwoofers match Martin Logans

[Sasha_G]

A number of people have been asking how Hsu subwoofers match Martin Logan Speakers. For those who don't know, Martin Logan makes high end curved electrostatic speakers. It is hard to get electrostatic speakers themselves to go down deep enough to reproduce bass because the size of the electrostatic speakers must increase to giant sizes to reproduce those frequencies. Often, these speakers will go down deep, but not down to 20 Hz at the limits of human hearing.

Electrostatic and full range ribbon speakers have low distortion and a number of other characteristics that leads listeners to label them as "very quick". Our subwoofers also
have low coloration, high accuracy, and good tight bass that can keep up with the high speed of electrostatics and full range ribbons.

Most electrostatic and full range ribbon speakers go deep, but not all the way down to 20 Hz--let's use 30 Hz as an example. When you need a subwoofer to do 30 Hz and down, several things are important.

1) The subwoofer's crossover must have a steep slope so the bass gets out of the way quickly. All our amps use a stacked potentiometer design in the crossover section that results in a steep slope and rapid elimination of the bass where you don't want it. That slope is 24 dB per octave. Other crossover sections in some other subs claim the 24 dB per Octave slope, but at the lower frequencies the slope actually becomes less steep. This is common even in some very expensive subwoofers because they used a cheaper crossover design on the inside of the amp where important work is done.

2) If you are buying a subwoofer to only play below 30 Hz (for example), it should do so well. Hsu TN subs are an excellent choice because they go down to around 15-16 Hz plus or minus 3 dB.

The Martin Logan website is here:

http://www.martinlogan.com/

[VTrogue]

Would it make more sense to have your crossover at a much higher frequency? Most ribbons go down to around 40/50 hz but i would much rather listen to your base then the average base coming from a ribbon speaker. This would also take some of the strain off of the ribbon speakers...........would a 80 hz crossover be better?

[Sasha_G]

Many Martin Logan's have their own bass units built in and go quite low. Their owners might prefer to use the built in bass unit. That is why I used 30 Hz as an arbitrary example. Since many electrostatic and full range ribbon speakers only go to 50 Hz, the subwoofers would need to be set at 50 Hz for those speakers.

Keep in mind that I'm refering to a preamp setup. If you are using a Dolby Digital Receiver, than the receiver will usually be doing the crossover duties, not the subwoofer.

A *higher* crossover than the speaker's bass response makes sense when you want to spend a litte more to reduce the demands on the main speakers. Many people prefer the sound of our bass more than the standard electrostatic bass. In this case you would need to use what is called a "high pass filter" to keep the bass out of the mains, and let the subwoofer do the bass duty from that point on.

We offer two solutions, depending on your setup.

If you are using:
Preamp + Hsu Amp Powered Sub
Then you need....
The Hsu High Pass Filter http://www.hsustore.com/high-pass.html

If you are using:
Preamp + a TN Series sub + non-Hsu amp
Then you need...
The Hsu High End Crossover: http://www.hsustore.com/highendcrossover.html

The frequency used should not be any higher than 80 Hz, because bass begins to become more directional and localizable then. Some people are more sensitive to bass direction than others, maybe because they can discern slight differences between the volume in the left and right ears more. For 99% of the people, I would say no higher than 80 Hz would be best.

[kalleda]

I've just bought the martin logan Aeon i, Script and Cinema speakers and have been told that one needs to get a "fast" sub for this setup. Was wondering if anyone could help point me to the right HSU sub for this setup. I plan on using it for both music (mostly) and HT. The room size is about 15 X 18 ft. I do not listen to music very load.

[Lwang]

Would it make more sense to have your crossover at a much higher frequency? Most ribbons go down to around 40/50 hz but i would much rather listen to your base then the average base coming from a ribbon speaker. This would also take some of the strain off of the ribbon speakers...........would a 80 hz crossover be better?

It would depend on the type of speaker you have.

With Martin Logan hybrids, they are basically using cone drivers in the bass region, so they by themselves would go pretty low already. But at the same time, integrating from cone woofer to cone subwoofer would not be as hard an issue.

But if you get the higher end Martin Logan speakers, they have a variation of the dipole woofer, so integrating from a dipole woofer to a monopole subwoofer would be a little trickier.


As far as integrating with a full range ESL or planar magnetic, it is not whether those drivers could not handle the low bass, thereby letting the subwoofer take over early on. It is the fact that going from a boxless/open baffled, whole membane drive, dipole design to a driver that is housed in a resonance inducing enclosure. There is a drastic difference in the way the driver pressurizes the room, and crossing over at a too high a freq would change the nature of the bass produces being perceived by us. That is why it is often preferable to cross the sub at a as low freq as possible.

Some people prefers to bass augment the speaker's bass, letting the sub take over where the speakers starts to roll off. This might not increase the headroom much, but those speakers usually roll off naturally below the operating freq, with the only limiting factor being slapping of the membranes.

Other people would bi-amplify or use bass management to reroute the bass to the subwoofer. But Dolby's 2nd order high pass for the mains seems to be inadaquate for this situation from preventing ultra high excursion bass from still reaching the main speakers. Either way, you want the subwoofer to be completely out of the way, much before we even reach 80hz.