Whole-House Audio, Vintage Style

•December 4, 2017 • 2 Comments

I just set up a simple but beautiful vintage setup in our new reading room: Pioneer SX-1080 and a pair of Klipsch Heresys Series I. I saved the Pioneer from a neighbor and fully cleaned and lubricated all of the switches, panels, and lights. Looks and sounds great. The Heresys just arrived from their first owner, who purchased them in 1984 and is now downsizing pending retirement.

Together the Klipsches with Pioneer is a great pairing. The super-cool power meters on the pioneer bounce along to the music, albeit only a tiny amount given the efficiency of the Klipsches.

I’m impressed with the bass performance of the Heresys given their reputation as a bass-light speaker. The lowest octave isn’t strong but is present, and the mid bass is balanced. Perhaps my wall placement is helping here.

This system is getting a lot of playing time at low levels, pushing background jazz and classical through the house. Some would say the magic of the Heresys are lost in such an application, however I’m finding the opposite – in critical listening these immaculate but middle-aged speakers are missing some of the dynamics and detail of other Klipsches I’ve had, and their polite bass makes them only mediocre party speakers. The horns seem to project well and I’m getting really nice sound projecting through different rooms. The Pioneer’s excellent FM reception is helping here too.

These Heresys are beautiful and deserving of some more attention. I plan on putting in new capacitors and inductors to liven up the sound, and perhaps adding some damping material to decrease resonance and improve bass response.

CAF 2017 Recap

•November 9, 2017 • Leave a Comment



Living in the DC region has its pluses and minuses – there are lots of great free museums, a ton of sports teams to root for, schools are pretty good, and you’re never too far from a protest. And group karaoke is an adult competitive sport. There are also minuses aplenty – traffic is universally horrid at all hours, it’s a swamp (literally and politically), group adult karaoke is REALLY competitive.

One of the unequivocal pluses has to be the critical mass of audio hobbyists and stereo nuts. One of those nuts (using this term as endearingly as possible) is Gary Gill, who has been organizing an audiophile gear and trade show called Capital Audiofest for over a decade. It’s grown into a massive event with almost 100 exhibitors of speakers, turntables, receivers, amps and other assorted audio esoterica. Everything you can imagine is there to see, with an emphasis on high-end gear, extreme performance and impeccable style.


Classic Audio Loudspeakers T-1.5 Reference. 18″ woofer, 15″ midbass woofer, 4″ Beryllium diaphragm midrange compression driver mounted in a wood tractix horn. 

Consumer brands were not well-represented, with a couple notable exceptions – TAD (affiliated with Pioneer) had their Reference line available for demos in two rooms, and Technics brought their new GU-8700 digital integrated amplifier, a couple pairs of their reference speakers, and an all-in-one media player/amplifier, all driven by one of their two latest 1200 series direct-drive turntables.


Technics SB-C700 speaker. Coaxial, designed by HAL 9000


Technics Grand Class SU-G700. I’m a sucker for meters.

I really liked hearing the Grand Class SU-G700 integrated amplifier. It’s a full-digital amplifier, which means it transmits to the speakers in a lossless digital signal, even converting analog input signals to digital using high-performance onboard Burr-Brown DACs. It pushes 70 watts into 8 ohms and 140 into 4 ohms, which is plenty for most speakers. I’d love to carry one home.

The German Physiks speakers were unique – one massive carbon-fiber unidirectional cone sticking straight up, with a woofer stuffed into the base. Kind of a modern take on the old Ohm Walsh speakers, except for $30k+. They sounded great and looked like aliens.

One of my favorite speakers to listen to were the Audio Charney Companions. Each the size and shape of a mailbox, he Companions had one 5″ Voxativ full-range speaker perched on the front of its exquisite woodwork. Looking under the rear of the speakers revealed a 104″ folded horn crafted out of smoothed birch. Running off of a quarter watt of tube amplification, these things roared, pulling rib-scraping cello riffs across the soundscape. They’re rated down to 40hz and my bowels can attest they get down there or farther. Unbelievable.

Turntables came in all shapes and sizes. Prices were uniformly high – the cheapest VPI I sampled was $900 and sounded great. Others on hand reached into six-figure range. I have to say that on these price-no-object systems, vinyl took on a new life. I was amazed at the clarity and color pulled out of the discs. I didn’t even think it was possible, and wonder whether sound engineers mixing some of these revered jazz pressings in the 1960s could ever fathom that some day there would be audio systems capable of completely bringing these artists back into the flesh.

My favorites still have to be the Vanatoo Transparent Ones. They’re small, relatively affordable ($499) powered speakers with integral DAC. They shouldn’t be my cup of tea – no horns, no tubes, no ancient walnut veneers – but they’re happy. They sound happy. Well-rounded, accurate, beautiful imaging and detail, no fatigue at all. 60 watt amps run a 5 1/4″ aluminum woofer and a silk dome tweeter with a passive radiator on the back. They’re tiny, 6x10x8 inches, and that’s even with one of them packing the amp, USB, optical, coax and analog inputs, a set of speaker outputs, a run for a sub, and volume, bass and treble controls. It’s a whole system in the palm of your hand. This is the third year I’ve heard the Vanatoos, and they, more than anything make me question why I obsess with the rest of the audiophile gear. They really sound that good. I took a picture of the new Transparent Zeroes, which are even tinier, pack more tech, and sound excellent as well. I kept coming back to the ones, however.



I don’t remember what these are, other than they are open-baffle arrays. Those are large brass discs hung on there too, to eliminate resonance. I guess that a slight curve to the disc increases their rigidity, so each is slightly unflat. Neat.


These are speaker cords with massive, humungous rare-earth magnets to do something or other. Maybe nanoparticles? They look neat. And it’s been featured on The Discovery Channel.


Showcase of beautiful gear. The stands  themselves are likely worth more than my car.

My second favorite speakers were these Odyssey Kismets. Simple principle – one Scanspeak Revelator woofer and one illuminator tweeter. Put to good use.



Here are the gorgeous Fern and Roby horn speakers with mid-range box. Dipole dual 12″ subwoofer next to it. Amazing craftsmanship.




5 Years and Back to Posting

•November 6, 2017 • Leave a Comment

It’s been over a year since my last post and over 5 since I started this blog. I’m thankful for all of the interest and comments in my posts. I have a lot of speakers and amps to report on since my last post and even more things I’ve learned and want to share with everyone.

I’ll re-commit to posting, and am adding new channels to Silver Face Stereo: You can follow me on Instagram @silverfacestereo and look for my Facebook page .

In the meantime I’ll share a few images from my recent acquisitions, with a promise of reviews and even more gear to come.



Update: CA-2010 is alive

•January 16, 2016 • Leave a Comment

Just back from a cleaning if all the pots and switches, including the coupler on the back. A short demo indicates clean clear and even output from both channels. We’re in business!  Next step: clean the faceplate, knobs and switches and restore the cabinet. 


•January 10, 2016 • 1 Comment

Just picked up a complete Yamaha CA-2010 and CT-1010 integrated amplifier/tuner pair. Everything lights up from beneath a film of dust and grime. I was told one channel is out on the amp. I’m hoping that’s just from corrosion in the pre-power amp coupling switch on the back – a common problem.

Will update after a thorough cleaning.


the offending coupling switch


Yamaha CA-1010 140 watts per channel



Yamaha CT-1010 tuner. Top of the line


Update with Sansui 7070

•December 10, 2015 • 1 Comment
Sansui 7070 receiver after some outpatient circuit surgery to get the lamps glowing

Sansui 7070 receiver after some outpatient circuit surgery to get the lamps glowing

I just found a forlorn Sansui 7070 receiver at a local record store. It’s in pretty good shape – everything is there and it sounds really really good. The lamps in the front didn’t all light up until I banged on the top of the unit. It turns out that the light board is notorious for poor solders. After about 10 minutes of reheating all the solder joints on the board I got all but one lamp to glow. Now it looks great.

The fake plastic veneer on the cabinet is peeling so I’m thinking about replacing it with some real cherry veneer on adhesive backing I have laying around. It should be a quick and nice-looking fix.

I wouldn’t bother if this thing didn’t sound so damn good. On a lark to test I hooked it up to my very power-hungry Polk Lsi7s and was absolutely amazed – this receiver sounds clear, clean, and amazingly pleasant. And it has the current to drive some pretty inefficient monitors. This thing is staying for a while!



I pulled off the vinyl covering from the case and re-veneered with the real cherry I had laying around. Picture below is pre-sanding. Now it’s looking very nice indeed.

Looks so nice I may not stain it.

Looks so nice I may not stain it.

Heritage Klipsches: Cornwall and Forte II

•December 10, 2015 • 2 Comments
Klipsch Cornwall Detail - logo and custom grille on bullnose

Klipsch Cornwall Detail – logo and custom grille on bullnose

I’ve recently had a run of Klipsches come through the house.

First was the pair of Klipsch Cornwall speakers in beautiful naked birch finish that I found in the spring of this year.

Cornwalls are the flagship of the direct radiating bass speakers in the Klipsch Heritage series.

What does that mean in English? It means that Klipsch is all about horns – enclosures which surround a driver and shape the direction of the waves. They are a good way to tune which frequencies are accentuated from a driver, where they go, and how they sound. They also boost efficiency of speaker systems considerably.

Klipsch Cornwall in Builder Birch

Klipsch Cornwall in Builder Birch

The biggest Klipsches in the Heritage series, the Klipschorn, Jubilee, and Belle Klipsch, all use a horn tweeter, midrange (also known as ‘squawker’) and woofer in a folded horn enclosure.

The Cornwall is the largest of the Klipsch speakers below the folded-horn woofer designs. That means its 15″ woofer just sits in the speaker like everyone else’s designs – it’s not hidden within the cabinet.

To get the desired bass, that means the Cornwall is large – 36″ high, 25″ wide, 16″ deep and easily 70-90lb apiece.

Detail of the Klipsch Cornwall Birch finish. Beautiful after 3 decades

Detail of the Klipsch Cornwall Birch finish. Beautiful after 3 decades

The pair I had were made in the 1970s and came in ‘builder’ spec – which meant an unfinished birch veneer and no grille. These models were intended to be sold to installers who would add their own veneers or enclosures. By the time I got my pair it had acquired optional grilles and bullnose (the surrounding of the grille on the fascia) and small risers. Interestingly the grilles were nailed on behind the bullnose – no looking at the speakers from the front.

Cornwall grille detail. No way to get these off.

Cornwall grille detail. No way to get these off.

The grilles were in excellent condition, and the veneers, despite some dust on the lower reaches, were in great shape. I was really worried about the veneers. – birch is pretty soft, and these had survived 40 years with no protection whatsoever. I didn’t want to mess them up. When I got them I didn’t even oil or polish them, just a little warm water on a damp cloth to pull the dust off. They are beautiful.

I liked the sound too. Very smooth and well-balanced. I found them very similar to the Klipschorns I used to have but easier to place since they don’t have the corner-horn placement requirement. The forward-mounted woofer concentrates the bass right with the mid and tweeter.

I didn’t crank these enough to have any problems with too-forward treble or mid, just a very nice presentation.

Even though they are much easier to place and live with than the Klipschorns, these were still too wide for my space and found a new home in a beach house in Deleware.

They came along with a pair of Tangent 5000s, which are seen in the pictures alongside the Cornwalls. The Tangents were a gap-filling model line between the Heritage line and later CF and Reference model lines. These Tangent 5000s were basically a Heresy II with a passive radiator on the back in a much larger enclosure. I bought them because the components and crossover were the same as the Heresys, and I planned on putting them into a smaller and better-damped enclosure and get a modded Heresy. But I couldn’t gel with the sound – even with the larger enclosures there was surprisingly little bass – I suspect that a woofer may have been wired out of phase. The downside to the Tangents notwithstanding their great components was the cabinet-  it was thin and much flexier than the Cornwalls, KGs, or Fortes I would later have. I’m sure they contribute a lot of negative resonance to the tangent’s sound. They left before I could figure out how to re-purpose the components.


Klipsch Tangent next to the Cornwalls

Klipsch Tangent next to the Cornwalls

Then a little later on I came across a pair of Forte IIs in Walnut. In excellent original condition – the grilles had never been off. I bought them from a record store that had accepted them in trade from the original owner.

These I like. Very well balanced with a Tractix mid horn on the front with a 12″ woofer and a 15″ passive radiator on the back. The sound and presentation is exceptionally smooth and well balanced. I’ve heard these described as the best of the Heritage line – advanced and balanced mid and high range horns, good bass response, very good efficiency, all in a manageable size. These are really nice. But alas they could not kick my mighty CF-4s out of the rotation and I don’t have anywhere else for them to go. They were competing for a while against my modded Polk Monitor 7s, but I’ve found that since the Polks’ new crossovers have burned in, they have an amazing synergy with my Harmon Kardon 3380 receiver in my living room and I don’t want to mess up that mojo – I finally have a system with great imaging and detail, good bass (amazing bass for a Monitor 7!) and clarity in a room with terrible acoustics.

Klipsch Forte II in Walnut. Beautiful shape, beautiful sound

Klipsch Forte II in Walnut. Beautiful shape, beautiful sound

Klipsch Forte II walnut veneer

Klipsch Forte II walnut veneer

Tube time: Fisher 500C

•June 22, 2015 • Leave a Comment
Fisher 500C Receiver

Fisher 500C Receiver

This was a long time coming.

With all my tinkering and trying of new stereo equipment I’ve tried to maintain objectivity in the face of what is a very subjective hobby. The internet is full of people who swear by multi thousand-dollar runs of speaker wire, while others maintain lamp cord sounds the same. Class A vs Class B vs Class D vs Tripath amplification – people swear up and down the sides of each. Subwoofers and monitors beat full-range speakers, or vise versa.

There are a few tropes:

Vinyl is more lifelike and warmer

MP3s just suck

Tubes are warmer and richer

Solid state is tinny

I couldn’t even get through writing those without coming up with a million challenges to each one out of my own limited experience.

So it was with a high degree of skepticism and anticipation that I tried one of the heralded heavyweights of vintage hi-fi – the Fisher 500C receiver.

These are tube-powered 35 watt per channel receivers from the 1960s. Search the web- people love these things and they reportedly perform right up there with newer audiophile tube rigs costing thousands more.

The one that came to me has been restored and upgraded with audiophile-caliber parts by local tube audio specialist Bill Thalman of Music Technology Inc (formerly of Conrad-Johnson) and sports Telefunken 12AX7s and a band new matched quad of Electro-Harmonix 7591 tubes.In addition to the recapping, the speaker terminals were upgraded to Cardas gold-plated binding posts and the old ungrounded power cord was replaced with a grounded socket. Sweet.

So this is not a stock example, but one that has had some care and attention lavished on it. And it looks great with a brushed aluminum face, real glass faceplate with immaculate blue “The Fisher” lettering and bird logos, and thick walnut cabinet.

Fisher 500C Receiver top view

Fisher 500C Receiver top view

I was really excited to try it out. At first I hooked it up to my CF-4s and plugged in my iPod for some quick demos. It was neat. I played a few songs and was getting used to the sound. the one real first impression I made was how strong and clear the FM tuner was – hah! Then I went to plug in my CD player to sling some discs and there was a flash and smoke came out of the chassis.

Oh no! Did I just kill this amazing receiver? How? This has never happened before with one of my transistorized amps.

So the 500C went on the bench for a few months while other projects took precedent. But once I opened up the bottom and looked in at the spaghetti mess of capacitors and resistors, I saw some obvious burn damage along the right side of the chassis – the conduit carrying wiring from the front-mounted power and volume switch back to the auxiliary sockets on the back of the amp was burned – somehow the wires had shorted and caused the blackout, maybe taking one capacitor with them.

Fisher 500C receiver. View from the underside. No circuit boards here!

Fisher 500C receiver. View from the underside. No circuit boards here! The blue and white wires running at the top side of the receiver are the new ones from the switch.

Once I replaced the three wires and the capacitor I switched on the receiver and now everything seems to be OK. I’m still a little worried that there may be some more trouble in there and I’m watching for weird behavior or smoke now constantly, but I had it running for an hour the other day with no issues whatsoever.

Detail of the fried power line conduit.

Detail of the fried power line conduit. The new wires are the blue and white ones to the right. They are crossed to limit interference.

And I finally had a chance to listen a bit more closely. Very impressive!

Detail of blown capacitor

Detail of blown capacitor

With the efficient CF-4s, the Fisher doesn’t have to push too hard. Bass is round but not sloppy and displays accuracy. What’s most interesting to me is the soundstage and imaging. Treble is not rounded or cut down – every note is there. It’s not shrill either. Most interestingly I’m picking new notes and elements out of music that I’ve never ever heard before, and in a new way. Some super-accurate solid state amps wow you with the detail but the way this Fisher puts every note, instrument and voice in the right perspective is something different – everything is where it should be, not just highlighted for you to check off the list -“yep, I heard that cymbal, this is a good amp.”

The Fisher lets you listen critically and still enjoy the music, which are often mutually-exclusive things for me.

Interestingly enough when I switched from the iPod Classic to my Sony ES Blu-Ray player the sound changed a bit. Imaging, soundstage and detail were still there. But there seemed to be more forwardness to the treble. I actually turned down the treble knob a bit on the Fisher. Surprising. I wonder now if the accuracy of the Fisher is bringing out a stridency in my CF-4’s horns. I’ve never heard it before but the Klipsch forum is full of mods for damping the resonance in this particular horn and bi-amping the speakers to bring the horns in a more acceptable level with the woofers. So now maybe I have more work to do.

Lots of room to work on everything.

Lots of room to work on everything.

Even my wife was impressed – she was blown away by the Fisher’s performance on CD with the big Klipsches, and remarked that a bit of forwardness in the horns was acceptable for the quality of sound we were getting. She also made a very good observation – it’s a mark of the Fisher’s excellent sound quality that it’s bringing out these deficiencies in such amazing speakers as the CF-4s. We played some of the same CDs then back on my Marantz NR-1403 AVR and there was a definite change in the sound – I heard it as flatter, however perhaps with a slightly wider overall soundstage (at least on CD). My wife heard no comparison whatsoever. She said the Fisher justified whatever price I paid for it.

I love that woman!!!


Fisher 500C reveiver. Rear view with the walnut case removed

Fisher 500C reveiver. Rear view with the walnut case removed

Updates – Tubes, transistors and other things

•June 19, 2015 • Leave a Comment

I’m writing up a few longer posts right now but here’s a quick update of recent developments:

My Fisher 500C was resurrected and I’m playing with it now. More detailed write-up to follow.

Fisher 500C back from the dead and sounding great

Fisher 500C back from the dead and sounding great

I just picked up another Pioneer SA-6500ii that wasn’t working. After some TLC it seems to be doing fine. It needs a cleaning then I’ll play with it some more. it also came with a dirty TX-606 tuner, which looks cool.

Interior of Pioneer SA-6500ii integrated amplifier. Pretty simple and easy to work on.

Interior of Pioneer SA-6500ii integrated amplifier. Pretty simple and easy to work on.



I also just picked up some Electro-Voice LS-12 Wolverine 12″ full-range speakers in some original-equipment enclosures. they look neat. And when I opened them up the Wolverines are in time-warp condition. My initial testing found everything was OK but I’m not sold on the sound yet – in the enclosures there’s a lot less low end than I was expecting. Maybe this is a good time to experiment with open baffles.

Epic – Klipsch CF-4

•May 13, 2015 • 7 Comments
Klipsch CF-4s with the grilles off.

Klipsch CF-4s with the grilles off.


These came home with me shortly after the Klipschorns and my KG-4s left. The Klipschorns were bigger than life in everything – sound, presence, weight – and even though these are speakers of a lifetime for many, I couldn’t warm to them in the end. They were awesome but required a lot of compromises, at least for me in my space. The KG-4s were harder to part with and after I bid them goodbye I regretted it almost immediately. The KG-4s are really ideal for background listening – their lively horn dynamics and ability to hit hard and low compromise them as critical listening speakers at higher levels but do the opposite at low levels. I’ve replaced them with my restored Polk Monitor 7s which I love but don’t project as much bass.

CF-4. Courtesy of Klipsch

CF-4. Courtesy of Klipsch


But then I found the CF-4s. As I started with the Klipschorns I became a lurker on the Klipsch Community forum. Klipsch Community is great – nice folks full of great advice on Klipsch sound systems and many other things. It’s similar to the Polk Forum (which I’ve lauded before) in that aspect. But as much as the Polk folks love to mod their speakers, Klipsch people do too, and they take it even further – replacing components, remodeling horns and tweeter diaphragms, testing new cabinet and speaker reinforcement and damping techniques. Very impressive. But sometimes all of these mods introduce a bit of the ‘Grandpa’s Axe’ paradox – after 5 new handles and a couple new heads, is Grandpa’s axe still the same old tool he’s always had?

CF-4s have a legendary following among Klipsch aficionados. They were envisioned by the legendary Klipsch designer Roy Delgado, who reportedly considered these his favorite design of his career. The legend is that the CF-4, while amazing, strayed too far from the traditional Klipsch Heritage sound, and dealers wouldn’t or didn’t know how to sell them to their clientele. Eventual mods in subsequent model years added sizzle to the tone in a bid to get the dealers back on their side, but high cost (they were almost $4,000 new), expensive components, and low sales numbers led to new models replacing them in 1996, after only 3 model years. CF-4s were the flagship of the Epic line, which also included the CF-3 (dual 10″ two-way, same horn) the CF-2 (8″, different horn) and the CF-1 (6.5″ woofers, 1″ horn)

Closeup of Cherry veneer on my CF-4s. Very thick and nice. A little oil and they gleam

Closeup of Cherry veneer on my CF-4s. Very thick and nice. A little oil and they gleam

The CF-4s paired two 12″ neodynium graphite-cone woofers with a massive 2″ aluminum-domed compression driver in an equally-large tractix horn placed between the woofers. The woofers crossed over at 1500hz into the horn. Klipsch reported a Klipschorn-rivalling 102dB @ 1watt/1meter efficiency, which may not be accurate – these things bump on little watts, but not that little.

The three drivers are housed in stately 44″ x 17″ x 19″ cabinets, which are only dwarfed  by Klipschorns. They weigh about 60lb apiece, which is surprisingly light for their size. And they come with two port holes at the bottom that are big enough to stuff your fist into.

When I first brought these home they were going right into the spot that the Klipschorns had been. Any my first impression was how much smaller they were than the corner horns. When I plugged them in to my trusty Lepai 2020+ amp I was blown away – other than being smaller than the Klipschorns, these speakers gave up absolutely nothing – CF-4s hit harder and lower and provided a much more even tone across the spectrum – no cut outs in the upper bass area like the Klipschorns. Even with almost no experimentation with placement, imaging was uncanny. I was in love.

These are forever speakers for me. I’m not giving these up. They just do everything too well. Well, that’s not entirely the truth. The fact of the matter is, I picked up two pairs at the same time when I found these – both pairs were made at about the same time in the end of 1994, with both having sequential serial numbers for their pairs. I ended up keeping the pair with the earlier serial numbers and the slightly more-dinged cabinets and I traded the other pair for a Fisher 500C receiver. But that’s when the mysteries began.

Remember how I said that Klipsch changed the CF-4s along the way in their 3-year run? Klipsch devotees refer to these as Series 1, 2, and 3 speakers. Series 1 were made how God and Roy Delgado intended, with a balanced sound, 6″ bass tubes in the ports, and a crossover set up to match. They also had Monster wiring inside. Series 2 got shorter ports to raise the box tuning and efficiency to make them hotter. Series 3 got different woofers of lesser quality and standard small-gauge colored wiring inside the cabinet. This all according to legend. Series 1 speakers are revered, Series 2 less so, and Series 3 denigrated. At least on the forums.

The Monolith Beckons

The Monolith Beckons

I thought my speakers’ serial numbers placing them in 1994 automatically made them Series 1, Series 2 didn’t start until 1995. But here’s where things get weird. The pair I traded (with the later serial number) has the Monster wire of Series 1 but it has the shorter ports of Series 2. And it’s hard to tell but it may even have the lighter woofers of Series 3 – one of the woofers died and the new owner replaced it with an identical woofer reportedly taken out of a pair of CF-4 Series 3 speakers. My pair has the longer port tubes but has colored internal wiring. And the woofers look the same as in the other pair. Both sets of speakers also have horn material which is a dark color, as opposed to the grey reportedly used on the earliest CF-4s.

People who know CF-4s know all of these little details like it is gospel. Amazing, I know. But that doesn’t explain how my speakers became such a mismatch according to the lore.

So I really don’t have any idea what series speaker I have. And at this point I don’t care. I’ve stopped reading the forum posts which say one pair is better or worse than another. I know that these speakers are something very very special. And when I’m ready there are a host of very cool mods that I can employ to take these to the next level, including cabinet damping, dynamat on horns and baskets, crossovers, and even new (even more humongous) horns. I’ll be ready.


UPDATE: I looked inside the other speaker and it has the clear-coated wiring reportedly used in the Series 1 CF-4s. So now who knows what these are. they still sound great.