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Bass tamer: Velodyne SMS-1

I might have mentioned that I have a relatively new pair of Merlin VSM-MXR speakers? Yes? Well, I do. And they’re awesome. The immediacy and intimacy of them are just crazy-good. They’re also wicked-fast and tonally spot-on. The bass is fast and tight, except when it’s not supposed to be, and it’s surprisingly deep for what’s essentially a 2-way bass-reflex monitor with an integrated stand that’s filled with an enormous amount of sand.

But that bass, while fast and tight (except when it isn’t), isn’t cavernously deep. In fact, the sound of the Merlins is almost definitely not “big speaker” sound — they sound more like point-sources than line-sources — so when you’re asking about room-shaking, gut-punching bass, the Merlins are really not up to it. And this is by design! The speakers do have a long-throw woofers, but still, 6″ is still just half a foot. There’s just so much they can do, and if you don’t like it, well, blame physics.

Or get some subwoofers.

When I bought the speakers, I knew about the BAM and the integrated roll-off for all frequencies below 29Hz. It’s there to eliminate any weird cabinet interactions, and in part, it’s why the speaker sounds so effortless.

But it’s still a problem. Especially if you’re looking to add that last octave back into the room.

So, what to do? Well, there really aren’t a lot of options. Let’s revisit a second.

  1. You could use a line out on your preamp to feed your subwoofers. The problem with this approach is the BAM. Where is it sitting? If it’s between your preamp and your amp (with separates), you’re good to go … except … the BAM isn’t supposed to go there. And in fact, if you don’t have clever grounding, its really quite likely that leaving a BAM here will in fact introduce a rather nasty ground loop and it’s hum. Bobby P, the head wizard over at Merlin, suggests that the BAM never be put here. Instead, he recommends buffering the BAMs output with a preamp — which means putting the BAM between your source and your preamp. But doing so means that all signal entering the preamp filters out all the low frequencies long before you can send a signal to your subwoofers. Oops.
  2. You could use a tape loop. This is option #2 with the BAM, and is Bobby’s least favorite implementation, even if it is the most flexible. A tape loop isn’t terribly fashionable these days, however. Plinius, for example, ditched the tape loop on it’s top-of-the-line Tautoro. Ayre did the same when moving away from it’s K1-xe. So, assuming you can find a preamp that sports a tape loop — a venture which looks ever more unlikely — you’re in business. BUT … the way a “real” tape loop works is that it’s an alternative path for the entire signal. All signal is shunted out the TAPE OUT, processed or affected there, and then sent back into the preamp via the TAPE IN, which is then eventually handed off the amp. So far, so good — but a LINE OUT on a preamp happens after the signal shunt of a tape loop (and the volume control, too), so any signal is still attenuated by the BAM. Rats.
  3. You can not use the BAM and simply use the EQ/XOver on the subwoofers. This blows. Don’t do it. The BAM adds so much sophistication to the sound of the Merlin floorstanders that without the BAM, they sound broken.
  4. You’re SOL.
  5. Get subs with a rather sophisticated built-in EQ. Unfortunately (at least in this case), the Merlins are wicked-fast, so your average run-of-the-mill subwoofer is going to be too slow and therefore muddy up the sound of your Merlins. To combat this, you’re going to have to be looking upmarket, like, say, at the JL Audio Fathom series. Going this route means that you should expect to spend more on the subs than you did on your Merlins. Which seems silly.
  6. Buy whatever subs you want and get yourself an outboard EQ system, like the Velodyne SMS-1.

My Velodyne SMS-1 showed up today. It took about 10 minutes to unpack and plug in and run through the EQ process. I went with the highest Q I could get (fastest response) and I ended up setting my pair of Rythmiks (it can handle up to three subs, but the signal is summed and not stereo) to run as high as 100Hz due to some persistent room nodes at 40Hz and 63Hz, and finally, I eliminated the crossover in the SMS-1. It went through a few test sweeps and Shazam!

I’m now plus/minus 3db all the way down to 20Hz.


How’s the sound, you ask? Much more integrated. Dare I say that it’s now seamless? The biggest change is now the sound doesn’t seem bass-heavy, lumpy, or boomy in any way. Bass notes are clean, distinct and have visceral punch. Mids are still uncluttered. Mid-bass is very dynamic, but now has serious body, which was a problem up to now.

It’s staying!

Honestly, I’ve been delaying purchasing this box because Velodyne released their upgraded Digital Drive Plus subs last fall, and I figured it would just be a matter of time before they released the same functionality in their stand alone unit. But, alas, it seems they have no intention of updating their SMS product, at least, no time soon. Oh well. Why did I care? Well the “Plus” has a USB out so you no longer need a TV/monitor to navigate the menus. Which would have been nice. Also, they apparently got WAY more granular on the EQ, making it much easier to get flat-as-a-board integration.

Well, no matter. The “old” SMS-1 works a treat. It has all the cables you’ll need, including component and s-video out as well as a nice microphone, stand, and a long XLR cable. I think they retail for about $450 online at a variety of shops.

Is it perfect? No. Ideally, I’d rather have a device that EQ’d each sub separately. Oh well. Maybe they’ll release a super-duper version next year.

In the meantime, get one! It’s totally worth it. Pretty minimal investment to make a rather dramatic impact to your system’s overall bass performance, actually. Highly recommended.

About Scot Hull (976 Articles)
Founder, Editor and Publisher at Part-Time Audiophile and "The Occasional Magazine"