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A review of the THIEL SCS4 Loudspeaker

Innovative design and high-end sound


Steve Kindig

Steve Kindig has been an electronics enthusiast for over 30 years. He has written extensively about home and car A/V gear for Crutchfield since 1985. Steve is also a volunteer DJ at community radio station WTJU, where he is a regular host of the American folk show "Atlantic Weekly," as well as the world music program "Radio Tropicale."

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The THIEL SCS4 is a high-performance bookshelf speaker. It's the company's most affordable model designed primarily for music. I'd been very impressed by the innovative design and striking sound quality of THIEL's flagship model CS3.7s when I reviewed them in May, 2007. While those 3-way towers did many things extremely well, I suspected that they were simply too much speaker for my room. The compact SCS4s are physically much more like my own speakers. Could less turn out to be more?

Not just another "box" speaker

The SCS4 is a 2-way speaker, but its design is unconventional. A 6-1/2" aluminum cone woofer handles the mid and low frequencies, and if you remove the speaker's grille, the woofer is all you see at first glance. But if you look more closely, you'll spot the 1" aluminum dome tweeter mounted coaxially inside the woofer. This design maintains the proper time alignment for the high and low frequencies, ensuring that everyone in the room hears the sound from both drivers at exactly the same time. It also allows both high- and low-frequency sounds to originate from the same spot, approaching the speaker ideal of a true "point source," for more focused imaging.

THIEL SCS4 bookshelf speaker
The SCS4's coaxially mounted tweeter ensures tight, precise imaging.

Two things you can count on with THIEL speakers are top-quality components and exceptional cabinet construction. Both the woofer and tweeter were designed from scratch by THIEL. The cabinets and driver materials exhibit extraordinary stiffness, which minimizes the unwanted vibrations and resonances that are the enemies of accurate sound reproduction. The cabinet is constructed of one-inch MDF and reinforced with plenty of thick bracing. A quick knuckle rap on the sides showed these cabinets are sonically inert. In addition, the entire front baffle is made of die-cast aluminum to further resist resonance.

My review pair of SCS4s featured a satiny black ash finish (natural cherry is also available). The stylish perforated metal grilles are held in place by magnets. The SCS4s' coaxial design means they can be placed either horizontally or vertically — in an all-SCS4 home theater setup, you could lay the center speaker on its side and still maintain excellent tone and imaging consistency.

Setting them up

I'd first heard the SCS4s in Crutchfield's training room. (Originally a 3-car installation bay, the room has received some acoustic treatments in recent years, but still presents a challenge to visiting trainers.) The SCS4s were paired with THIEL's matching SmartSub® SS1 powered subwoofer and PX05 passive crossover. With a Denon A/V receiver supplying the power, we listened to a few CD tracks. Even in that large room the sound was impressively clean and full. When THIEL asked if I'd be interested in trying out the SCS4s at home, I jumped at the chance.

Carting them over to my house and hooking them up required considerably less effort than THIEL's imposing CS3.7s had. Initially, I simply replaced my beloved ACI Sapphire III bookshelf speakers with the SCS4s: same position and same amount of toe-in. They were spaced 8 feet apart and 8 feet from the center of the sofa where I normally sit. My listening room measures 13-1/2 feet wide by 24 feet long, with a ceiling just under 8 feet. The speakers fire into the length of the room. I placed the SCS4s on the same 24-inch stands I use for the Sapphires (bookshelf speakers perform best on high-quality stands). You can read about the other equipment I used for this review at the end of this article.

As high-performance speakers go, THIELs are not particularly "high maintenance." The SCS4s impedance is rated at 4 ohms, which means you'll get better sound if you drive them with a high-current amplifier. I'd recommend using at least a high-quality receiver with them. Their ability to resolve low-level detail and present a 3-dimensional soundstage will only be helped by pairing them with good separates. The better your source and electronics, the better these speakers will sound. The SCS4s' coaxial driver placement also means that these speakers are less fussy about placement. You don't have to spend a lot of time moving them around to get great sound.

One other connection note: While many high-end speakers provide dual sets of terminals for bi-amping or bi-wiring, THIEL speakers do not. Jim Thiel's sophisticated crossover networks are designed to optimize energy response and tonal neutrality, and he doesn't want any unnecessary cabling interfering. Instead of buying a second set of wires, Jim recommends upgrading to one set of higher-quality cables.

Listening impressions — the start of something good

This particular pair of SCS4s had been used for training sessions for a few months, so they were already well broken in. To get a general feel for their sound, I began by listening to a few discs that had been spending a lot of time in my player recently. I expected to have to experiment with the volume and crossover settings on my ACI Titan powered subwoofer, to match up better with the THIELs, but the system sounded very smooth and balanced from top to bottom, with no hint of boominess in the bass. So I just sat back and soaked in the sounds.

What immediately struck me was a profound sense of clarity and effortless transparency. The SCS4s brought the music closer, allowing me to hear further into the mix on every recording. High frequencies were extended, but with no trace of edginess. The midrange was extraordinarily pure and detailed, with a palpable sense of presence. The SCS4s clearly outperformed my Sapphires in their reproduction of midbass and upper bass, sounding both more extended and more articulate. It was easier to pick out the melody in acoustic and electric bass lines. The SCS4s are bass-reflex speakers, with ports in their cabinets to extend bass output. Bass-reflex speakers used to have a reputation for woolly, "one-note" bass, but advanced designs like the SCS4 have left those limitations far behind.

Some high-end speakers are too "polite" for my taste — or maybe a better word is "uninvolving." They can reproduce the notes, but seem to polish away some of the music's rough edges: the hum of a guitar amp, the clicking of plastic picks against steel strings, or a singer's intake of breath. But the SCS4s always sounded robustly musical, providing an open window, a raw feed, a direct conduit to the performance. Their remarkable clarity made it easy to track multiple threads in the music. From the fluid Afropop of Tama's Nostalgie to the breakneck bluegrass of Carrie Hassler and Hard Rain, the sound had a cohesive 3-dimensionality that bordered on the physical. The Carrie Hassler CD in particular packed blazing instrumental runs that fairly leaped from the speakers.

On well-engineered recordings, the SCS4s created an open, spacious, densely textured soundstage that extended from wall to wall and floor to ceiling. Soundstage height was better than I'm used to, while soundstage depth was simply the best I've heard in my room, seeming to extend several feet beyond the wall behind the speakers. When I played Eric Clapton's acoustic version of "Layla" from his Unplugged CD, this track's relaxed, atmospheric vibe washed over me, and as soon as it finished, I had to hear it again. And again.

Listening impressions — further sharpening the focus

My colleague and fellow audiophile Dave Bar joined me one evening for some listening. I trust Dave's ears at least as much as my own, and while he was immediately impressed by the SCS4s, he also loves to tinker with speaker placement and other fine-tuning, so we tried a few things. After a few rounds of shifting the speakers then listening some more, we ended up with the SCS4s spaced a little closer together with a bit less toe-in, but left their distance to the sofa unchanged. This new placement sacrificed a bit of soundstage depth in exchange for a larger sweet spot and improved overall balance.

I also tried turning off my subwoofer, and the sonic picture grew clearer still. The sub had actually been "slowing down" the SCS4s in the midbass region. By that I mean that the overall sound grew noticeably more lively and nimble when I switched off the sub. With a lot of trial and error I probably could have tweaked the subwoofer's settings to create a more seamless transition from my sub to the SCS4s, but the THIELs' bass was surprisingly taut and tuneful for their compact size. Near the end of the review period, I dug out my trusty bass test disc and found that in my room, bass response was still strong down to a surprising 42Hz, but rolled off swiftly and was nearly inaudible at 35Hz. For listening to music, many people will be more than satisfied with the SCS4s' bass performance.

Dave and I continued playing familiar tracks and several times one of us said, "That's the best I've ever heard that sound." And as it got later, the music got louder. Little Feat's remastered Waiting for Columbus is one of the best live recordings ever, both musically and sonically. The southern-fried swamp boogie of "Fat Man in The Bathtub" put big smiles on our faces. The differences between the SCS4s and my Sapphires weren't night and day, but they were consistent and unmistakable.

So accurate, they expose system (and setup) weaknesses

I continued to enjoy the SCS4s, but I began to notice that something was slightly amiss: the entire soundstage seemed to pull a tiny bit to the right. It was subtle, but I noticed it on several recordings. When I checked my preamp's balance setting, I was surprised to find it tilted rightward. I don't know how long it had been like that or how it got that way. Probably me, but I also have folks over to listen pretty often and the remote gets passed around. It's easy to hit the wrong button. The point is that the SCS4's supreme detail and spatial accuracy made this setup flaw obvious. Once the balance control was correctly centered, the soundstage locked in even more.


Obviously, I was bowled over by the THIEL SCS4s. They've allowed me to enjoy the the best sound I've ever heard in my room. And frankly, as a diehard audiophile and 24-year Crutchfield veteran, I'm thrilled that we're carrying speakers of this caliber. At $2000/pair, the SCS4s aren't inexpensive, yet their exceptionally realistic presentation of recordings makes them a true high-end value. Their sound bears a strong family resemblance to that of THIEL's flagship CS3.7, but in a much more compact and versatile package. If the idea of experiencing your favorite recordings in a deeper way appeals to you, THIEL's SCS4s deserve your serious consideration.

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