Core Power Ground Zero

Got hum in your system that you just can’t get rid of? Is it driving you nuts? Have you tried power conditioners, cheater plugs, etc.? Still there? Still mad?

Chances are, there’s some residual DC in your power. It happens. For those of you that think “well, I’ve got clean power where I live,” you don’t. Because even if you live in the middle of nowhere, chances are, there’s something in your house dumping RFI or something back into your power line, and it’s causing havoc with your system. This can be of particular annoyance if you love vintage gear or SET amps and high sensitivity speakers.

Yes, yes, and yes. When the folks at Core Power asked us to review the new Ground Zero, I knew I had a handful of problems that could put this device straight to the test. First stop, my vintage Marantz 2220B receiver. This baby is a humasaurus. It’s always fine listening to the radio, but the minute I plug in a turntable or CD player, the hum begins. The only other thing that worked was plugging the receiver into a dedicated Goal Zero (different company) 2000-watt battery supply. And that’s not going to be convenient or cost effective for everyone. We just tried it because it was here and we were at the end of our rope.

As you can see from the picture, the Ground Zero has one outlet, and a 500-watt maximum capacity. Our past experience with all power products is to keep it a little below max capacity so you don’t stress things out and limit dynamics.

Plug the Ground Zero into your outlet, and your device into the Ground Zero. Listen to your system with the volume control all the way down and adjust that control knob on the Ground Zero for minimum hum. Hopefully, it will get you all the way down to no hum. The Core Power folks have some great measurements and graphs demonstrating this performance, and if you’d like, you can see it here:

Seriously, in less time than it will take you to hook up a scope, you’ll be able to hear what the Ground Zero does. If you need more current capacity, Core Power’s Deep Core 1800 may be the droid you need, but if you’re current and device requirements are minimal, the Ground Zero will get you sorted.

Next stop, vintage tube amp. The Dynaco Stereo 70 to be exact. This is another perfect example of an amplifier that’s been lovingly restored, but still has some residual hum going on. When plugged into our Pure Audio Project speakers, or Zu Dirty Weekends, it becomes bothersome. Quickly installing the Ground Zero offers the same fix. A little twist of the control, and the hum is no more.

Finally, the Line Magnetic LM-805IA integrated. This 48 wpc SET is lovely, but even after carefully adjusting the amplifiers’ hum controls for both channels, some hum still remains. Once you know you can dial it out, you want it gone all the time, right? This worked similarly well, however at maximum volume, when the VU meters were peaking, the slightest bit of compression and flattening started to happen. As Line Magnetic does not list current draw anywhere for this amplifier, I suspect at peak power, I was approaching the limit of what the Ground Zero could handle. At modest volumes, it was just fine, and for those of you with 2A3 or 300B amps, it should be all you need. We will have to get a Deep Core in to investigate with a few bigger tube amps.

When operated within its operational limit, the Ground Zero brings no compromise to the musical signal. Like a good doctor, we want power products to do no harm to the audio waveform. Running through a long playlist of both dynamic rock and classical music, along with a number of delicate acoustic pieces, it’s clear that neither dynamics nor tonality are affected by inserting the Ground Zero.

The Ground Zero works as promised, solves the problems it was designed to address, and is reasonably priced. Right now, Underwood HiFi is offering an intro price of $399 – even better. There’s no point in buying exotic four and five figure power conditioning products for an $800 vintage component, or a budget tube amplifier. For that, we are happy to award the Ground Zero one of our Exceptional Value Awards for 2021. If you’re having this problem, you need one.

As they say at the end of the classic tune, “Hot Rod Lincoln,” that’s all there is and their ain’t no more.

$599 (intro priced at $399)

Something new from REL Acoustics

Tomorrow, REL Acoustics will announce a major
upgrade to their best selling line of subwoofers.

Ahhhh, we’re under NDA, so we can’t tell you till then – but you can probably guess. But we have had the privilege to listen to these for the last few weeks, and we
can tell you that in addition to being sonically stunning (and better than ever – you’d expect no less from REL) they’ve subtly and tastefully updated the look.

Can only show you a sneak peek today.

We’ll have more news on our website, and a quick flyby video on our Facebook and Instagram pages as well.

A full review of the entire group will follow around the first of the month. We think you’ll really enjoy these.

Bowers & Wilkins 702 Signature Loudspeakers

Rocking out with some Slayer, it’s clear that Bowers & Wilkins has produced a winner here. To be honest, I’ve been punishing these speakers for about a solid week now, and it’s clear they have major dynamic ability.

Life isn’t all metal though, (though for some it is) and after seriously breaking these speakers in, an expanded palette of music was in order. Grooving on some Black Devil Disco Club, it’s easy to see that the 702 Signatures have plenty of low frequency ability too.

Bowers & Wilkins has always been a company driven by engineering excellence. I’ve owned a number of B&W speakers since 1980, and they’ve always made fantastic products. Having visited their UK factory a few times now, the level that they implement their engineering vision is second to none. Being a car guy at heart, I’ve always enjoyed the paint shop and the level of finish they are able to achieve. On both of my recent tours to the UK factory in Worthing, my tour guides have always made it a point to say that the B&W factory in China is a mirror image of the UK factory, though it concentrates on the 600 and 700 Series product. 800 Series Diamond product is made in Worthing. These are both huge facilities.

Even a cursory look at the Signature speakers proves that they’ve left nothing on the table, in terms of quality here. Where B&W has somewhat simplified the 700 Series is in the cabinet itself, with a more traditional box shape, instead of the complex, curvy shape of the 800 Series Diamond.

Unpack and setup

If you’re planning on buying a pair of Bowers & Wilkins 702s (Signature or not) read the infographic on the top of the box before you remove your speakers from their packaging. The 702 tweeter is housed in a bullet shaped aluminum enclosure that will be instantly damaged if you just put the box upside down once you’ve opened it. Get a friend to help you unpack your 702s because even though they are not terribly heavy, they are tightly packed and close to impossible to unpack by yourself because their slippery, smooth cabinets are hard to get a grip on. Save the little white rubber thing (that looks a lot like those rubber things they use in a nail salon to keep your toes apart) under the tweeter pod in case you move or ever have to ship your speakers. Trust me on this.

Once unboxed, you’ll also notice a pair of plinths that have been included for safety reasons in certain countries. If you don’t absolutely have to use them, I suggest leaving them in the shipping cartons, as they distract from the sleekness of the 702 Signatures, and B&W says the plinths do not improve the sound.

The last style decision to make is whether to affix the grilles or not. If you have kids, dogs, or a lot of guests, you’ll probably need them, but if you don’t, admiring the 702 Signature sans grilles is quite lovely. High technology doesn’t always look as good as it sounds, but in this case, the 702 Signature succeeds brilliantly. The three woofers, with their subtle chrome rings are just beneath the midrange driver with the big, silver Continuum™ cone, and the tweeter pod at the very top.

And, ooh those cabinets. From the outside, those stepping up to the $6,500/pair Signature series models over the standard $5,000/pair models you get a cool Datuk Gloss finish. I have to say, as a Sonus faber owner, Bowers & Wilkins is right there at the top of the mountain in cabinet finish, offering a level of quality that I’d expect to come from Italy. These speakers are absolutely beautiful to behold. The depth, and smoothness of the finish is outstanding. I’d step up to the Signatures just for the finish.

The Signature models are not just a cosmetic/finish update. Though the spec sheets between the standard 702 S2 and 702 Signature reveal the same numbers – this is the perfect example of specs not telling the whole tale. Thanks to upgraded bypass capacitors in the crossover, the Signatures deliver a more grain free presentation through the mids to the highest highs. The only downside here, albeit temporary, is those upgraded components in the crossovers take a bit more time to be all they can be. Expect a slight edge on top, and a bit of haze and fog through the midband for the first couple hundred hours of use.

To observe this process in action, play the same track every day at the beginning of the day. Make it a track you know intimately. In this case it was Robert Plant’s “Sixes and Sevens,” but I’m sure you have a couple of favorites that you’ll be able to notice the slightest differences. It’s almost as if the 702 Signatures get bigger and smoother sounding as you put hours on the clock.
Sticking with Robert Plant as my go to, shifting forward in time to “All the King’s Horses,” from his Mighty Rearranger album, the backing vocals started out somewhat buried in the mix, yet as the hours went by, I could hear the separation between Plant and the backing vocals much easier and more distinctively.

In our 13 x 18 foot living room, final speaker position ended up with the speakers being about five feet from the rear wall and about two feet away from the side walls. Only a few degrees of toe-in was used, but this and whether to slightly angle the speakers back will depend on seat height and personal listening preferences. Suffice to say that the 702 Signatures were easy to set up and get satisfying sound from quickly. Those needing to place their speakers close to the room walls or corners may want to take advantage of the foam plugs to insert in the rear mounted speaker port.

Other choices

With a sensitivity rating of 90dB/1-watt, the 702 Signatures don’t need a ton of power to be musically involving. Using everything here from the 30 watt per channel PrimaLuna EVO 100 to the mighty Pass Labs XA200.8s, proved a good match. Being that person preferring a more mellow approach, I gravitated more to the combination of the 702 Signatures with the Luxman L-550 Class A (solid state) integrated, the Pass INT25 (also solid state Class A) and our reference VAC Sigma 170i (tubes), but your final sound preferences will determine what you’ll pick. Bottom line, these speakers do not need a ton of power to sound great.

We also made it a point to try the 702 Signatures with a few different sets of speaker cable, from WireWorld, Nordost, Tellurium-Q, and Cardas. Again, all excellent results, how you want to achieve final voicing on your system will determine where you go here. The Cardas Clear cable in our reference system (a touch warm) was more to our taste, but the other three turned in great performances, but are slightly more forward and revealing. My living room is very lightly treated, so this contributes heavily to my leaning more towards a slightly mellow tonal balance.

One small tip, for those purchasing a pair of 702 Signatures: invest in a high-quality pair of jumpers, if you aren’t bi-wiring your speakers. Swapping a pair of Tellurium-Q jumpers in place of the factory issued, flat metal jumpers brought yet another level of clarity in the mid and upper registers.

What’s not to like?

Pretty much nothing really. Your decision will probably be B&W or the other choices, or between the Signature and standard models. However, in terms of what’s available in the $5,000 – $7,000 range that we’ve had the pleasure to audition, the Bowers & Wilkins 702 Signature is a solid player in terms of sound quality, engineering prowess, and aesthetic appeal. Not to mention, as one of the world’s largest speaker manufacturers, you can be sure of a great sales, service, and support network to go with your purchase.

The Bowers & Wilkins 702 Signature
MSRP: $6,500/pair

Please click here to be taken to the Bowers & Wilkins website.

REVIEW: The JBL L-100 Classic

In the 70s and throughout the 80s, the JBL L-100 was a very successful loudspeaker. Having a production run from 1970 to the mid-80s, the L-100 sold in more significant numbers than any other model, and perhaps one of the greatest selling speakers in audio history.

For those squealing about the $4,000/pair cost, a quick look at a currency calculator reveals that the $546 it took to buy a pair of L-100s in 1970 is worth about $3,700 in 2019. By comparison, a brand new Camaro (V8 sport coupe, not a Z28) back in 1970 was about $3,100, and a new Camaro goes out the door, moderately appointed (but still with a V8) is about $45,000. Clearly, JBL has done a better job of keeping pace with inflation. However, to be fair, a 1970 Camaro in great shape will fetch 50 to 100 thousand dollars at auction. A clean pair of L-100 originals about $1,500.

Considering what three to four thousand dollars buys in a pair of speakers these days, the new JBL will not be everyone’s cup of, but the value they do bring to the table is unmistakable. There are definitely more audiophile-y speakers out there, but to this writer, loudspeakers are like buying a painting. Some prefer the French impressionists, while others like Andy Warhol, and yet others like something else.

If you want more resolution and a broader sound field, think about a pair of comparably priced MartinLogans, or Magnepans. If you’d like a midrange that does a better job with the human voice, think about some Harbeths, Grahams, or ProAcs. We all know that there are tons of choices, and $4k/pair is an excellent speaker budget. You should be able to find something you love with four thousand bucks in your pocket.

Just as one person would rather peel out with a nearly 600 horsepower Dodge Challenger than get a wimpy four-cylinder Porsche Cayman S that is only about 300 horsepower (but goes around corners way better), it’s easy to see the attraction. Fun can be delivered within different paradigms and still be fun.

Comparing to the originals

It’s incredibly easy to let a romanticized past get the better of you. And as a boomer to all of you in younger generations, laugh now. Winter gets longer and more treacherous the older you get. It happens. But we try not to play it that way.

With a pair of mint originals at hand to make a direct comparison, it underlines even further what great speakers the new Classics are. The originals still have an unmistakable cool factor, and there are several updated crossover kits on that market that are claimed to make the originals otherworldly, but that has to be another day. One can only tweak so much.

Unlike today’s reimagined muscle cars paying fairly close visual homage to their 70s counterparts, the L100 classic looks incredibly close, whether the grilles are on or off. The pulp cone midrange driver (albeit updated) and woofer (same) are still in place, though today’s 12-inch woofer now sports a rubber cone surround, where the original featured a pleated paper surround. The paper coned tweeter in the original is now replaced by a titanium dome, which incidentally, JBL has done an excellent job at taming.

Best of all, the sculpted foam grille remains. When I sold these speakers back in the late 70s, everyone knew that grille. Whether on purpose or by accident back then, this was part of what made the L-100 an icon. And this charm remains. Foam choices are orange, blue, and brown.

My originals are orange, so it felt like a great idea to get more subdued brown ones this time. Fortunately, your JBL dealer can supply the other colors for $249 a pair, so I foresee some blue ones in my future. (Ed. note: since this was originally published earlier this year in our 100th anniversary issue, I have acquired a blue set, thanks to staffer, Tom Casselli, who now has the orange. Hmmm.)

While many snooty late 70s/early 80s audiophiles dismissed the L100 of the day, it was a much better speaker than many gave it credit for. Unfortunately, most mass-market retailers sold em with a crappy Kenwood receiver (or something else equally dreadful) that didn’t have the current drive to tame the woofer, or the refinement to get a decent top-end response. I always seemed to remember that connecting my pair up to a Conrad Johnson MV50 was pretty rocking, but again, that memory thing.

This time though, I was right. Hooking the original JBL’s up to the PrimaLuna EVO400 monoblocks with a full complement of EL34 tubes is indeed glorious, and in fact, even better than I remember.

Out with the old, in with the new

The L-100 Classics were far and away the hit of the 2018 Rocky Mountain Audiofest, even if they were hooked up to an awfully dry sounding Levinson amplifier. As part of the same conglomo, I’m sure they had to use that sterile, boring Levinson amp, but they should have pulled out a freshly re-capped Marantz 2275, or god forbid, a McIntosh MC275. Sometimes you have to cross party lines to reach the desired result. But I heard enough to get the essence.

Earlier this year, getting a pair of these for review proved nearly impossible. Getting someone at Harman to even pick up the telephone is almost impossible. So, kudos for making this review possible go to Mr. Steve Rowell at Audio Classics for putting this together. I rarely buy a piece of gear before the investigation even begins, but I knew I wanted to get old with a pair of these. Staff member Jessica Sieracki took the vintage ones off my hands after, so onward and upward.

Like several other speakers with a metal dome tweeter, the L-100 is slightly bright out of the box. This went away after about 50 hours of play and is gone entirely by 100 hours. The midrange and tweeter level controls are much more useful than they are on the originals and come in handy fine-tuning to your destination amplifier, cable, and room choice. My living room is a bit livelier than in the main listening room, so a nudge of the tweeter control in the counterclockwise direction is both handy and welcome.

How do they compare?

Now that these speakers have been out for just over a year, the internet abounds with multiple opinions, many centering around the L-100 classic, not being an “audiophile speaker.” It is, and it isn’t. If by audiophile speaker, you mean hyper-detailed, with pinpoint imaging, and pretty much no bass to speak of, then the L-100 classic speaker is not an audiophile speaker.

While attending a demonstration of another manufacturer, the fellow running the show said that when making a speaker, you can go for accuracy, or you can go for something more fun. Clearly, the JBL engineers went for the latter, as these are without question one of the most fun pairs of speakers I’ve ever used.

Like the originals, these are genuinely a garbage in/garbage out speaker. Pair them with  low quality, low-resolution equipment , and they will reveal what is behind them. Mate them to great electronics, and they stand up very well indeed.

The L-100s go deep. A comparable pair of mini-monitors from across the pond sound absolutely wimpy in comparison at first blush. But a side by side comparison with a pair of Harbeth Compact 7s reveals the Brit monitors to be cleaner and less cloudy through the mid-band – you can’t argue with the BBC. Think of the Harbeths as a cool white color rendition and the JBL’s a warm white rendition. I own both, I enjoy both, but if you have to choose one, it’s probably going to be down to your ultimate preferences.

The L-100s definitely go way down deep, but the character of the bass rendered is slightly warm. If you’re listening to classic rock or jazz, this is probably going to be pretty pleasant. Those of you on a quest for the absolute sound, whatever that is, will probably go elsewhere. Much like the originals, plopping a Joni Mitchell record on the turntable and easing back in the couch with the L100 Classics is one of life’s great pleasures. Especially with a good tube amp. I’d highly suggest the PrimaLuna, an MC275 or a VAC amp as my first choices.

The JBLs paint a fairly big sonic picture, but it’s more diffuse. While it expands slightly beyond the speaker boundaries, it’s not all-encompassing the way a pair of panel speakers or a perfectly optimized pair of Falcon LS3/5as can. They don’t entirely disappear in the room all the way, but that’s ok.

One other forgotten aspect is the ability to play at a reasonably convincing level. When the other speakers have long run out of dynamic capability, the L-100 Classics still have plenty of headroom left. Oddly, while they are slightly grainy in comparison to a few other speakers, this does not increase at higher levels. I’d venture to guess that some of the insight gained in studio monitor and sound reinforcement has trickled down to these speakers. If you want a pair of real rock and roll speakers, these will do quite nicely.

At the end of the day, the JBL L-100 Classics remind me a lot of that great American amplifier, the McIntosh MC275. It’s not the last word in any of the standard audiophile qualifiers, but I dare you to have a bad day listening to one. The same goes for the L-100 Classics. I dare you to have a bad time listening to your favorite music, no matter what generation it’s from when you’re rocking a pair of L-100 Classics.

And that’s their charm. Considering I’ve had a pair of the originals in one form or another for the last 40 years, the chance that these will be with me till the end is high. Want a good deal? Show up at the estate sale in 2055. I’m sure our kids will sell em to you cheap.

Classic ride, classic speaks. What’s NOT to love?

Issue 81


Old School:

VPI HW-19 Mk 3 Turntable
By Jerold O’Brien


Venture Electronics Monk Plus IEM’s
By Kyle Dusing

Journeyman Audiophile:

Rotel A14 Integrated and CD14 CD Player
By Andre Marc

TONE Style

Podium XL from HiFi Racks

The Bubble Sofa by Roche Bobois

Snap Power Light Outlet

Orvis WW1 Wooden Propeller

WireSkin Wine Bottle Carrier

42mm Timex + Red Wing Chronograph

Jackson Pollack Puzzle


Spin the Black Circle: Reviews of New Pop/Rock and Country Albums
By Bob Gendron, Todd Martens, Chrissie Dickinson, Andrea Domanick and Aaron Cohen

Jazz & Blues: Eric Hofbauer Quartet, Steve Slagel, and More!
By Kevin Whitehead and Jim Macnie

Bob Gendron’s Rock Reissues You Shouldn’t Miss

Gear Previews

GamuT Zodiac Speakers

MartinLogan Expression ESL 13A Speakers

Exogal Comet DAC


GamuT Di150 Limited Edition Integrated Amplifier
By Jerold O’Brien

SVS SB-2000 Subwoofer
By Jeff Dorgay

Esoteric E-03 Phonostage
By Greg Petan

Franco Serblin Lignea Speakers
By Jeff Dorgay

Plinius Hiato Integrated Amplifier
By Rob Johnson

VPI Prime Turntable
By Jeff Dorgay

Atoll’s HD120 and MA100 Amp and Pre
By Jeff Dorgay