Tannoy Berkeley (HPD385A), Review

Seeing how it’s been a little while since I’ve done a brief review of any of my speakers and my plans to go camping this weekend fell through, I dug my Tannoy Berkeleys out of storage.

I’ll forgo posting the history of Tannoy and the dual-concentric as it has been posted on several websites devoted to the drivers. If you’re interested, it’s worth a read of a company that started with a basic coaxial driver concept in 1947 and stuck with it with a few upgrades for nearly 60 years.

For nearly the first three decades, Tannoy went through several series of their famous dual-concentric drivers, such as the Black, the Silver, the Reds and the Gold series (so identified by either the color the basket was painted for the first two and the color of the magnet cover for the others), with the 15” being the flagship model. However, these series were all nearly identical with only minor variations in the actual drivers. They had accordion pleated surrounds and thick paper cones that made for very limited bass capabilities and were plagued by a significant amount of midrange coloration when the 14” nominal cones were asked to output above 1kHz. To correct these deficiencies, the crew in Scotland decided to undergo the first major redesign of the dual-concentric in the early 1970s that became the first HPDs.

To correct the cone breakup and subsequent coloration, the cone was made thinner and Girdacoustic struts were added to the back to keep the weight the same while making for a much stiffer structure. (Common knowledge in support of the Golds has it that these struts added weight, but the technical documents I’ve read [and subsequently cannot find again] indicate that the cones in the Golds and HPDs are the same mass. The majority of Tannoy owners do prefer the midrange colorations of the older units to the more accurate HPD and later series, oddly enough.) To compete against the new deep bass capable speakers coming out in the ‘70s, the pleated surround was replaced with foam dropping the Fs several octaves to a mere 14.7-20Hz (depending on what documents you refer to) and the voice coil was upgraded to allow higher power handling (quadrupling it to 85 watts continuous). While they were at it, the high frequency diaphragm was upgraded for increased power handling and extension to 20 kHz instead of the old 14-16 kHz limit. They did decide to keep their original special blend titanium enriched AlNiCo magnet, common to both the bass and treble diaphragms, and pepper pot tweeter thus preserving the phase coherent design.

I picked up my pair of Tannoy Berkeleys at a local Goodwill for $40 a while back. The voice coil on one was rubbing, but I eventually figured out the easy remedy of simply unbolting the spider (being that Tannoy firmly has its roots in the professional market, the cones are bolted in to be field replaceable) and realigning the voice coil to account for thirty years of suspension sag.

Since then, I’ve been fond of this original garage sale price tag that the Goodwill pricer decided to follow:


The Tannoy Berkeley is the second model down from the top of the very first run of the upgraded HPD drivers. Each 98 liter ported enclosure houses a 15” HPD385A dual-concentric driver. At a specified weight of 90lbs per enclosure, each driver accounts for a whopping 1/3 of the total system weight (the HPD385A is spec’d at being just a touch over 30lbs). This means that the cabinet is particularly light weight for such a heavy weight driver and so the panels are easily put into motion once the driver gets going with stronger transients.

Tannoy Berkeley in teak veneer with “sand” colored grills (the top grill covers the driver; the bottom covers the ports and treble level controls to allow adjustment without removing everything or to show the driver off without seeing the ports):


Berkeley sans grills:


HPD385A in situ (tweeter is hidden behind acoustically transparent dust cap):


Schematic diagram of the driver displayed right on baffle:

The woofer cone acts as a continuation of the tweeter horn flair. The distance between the HF diaphragm VC and woofer VC is a particular fraction of the crossover frequency wavelength. When the HF is connected inverse of what one would normally expect, the phase of the wave front is coherent at the horn/woofer transition. Later models using shallower ceramic magnets did not have the advantage of this mechanical alignment and needed a rather messy circuit added to the crossover that didn’t quite work as well as desired.

Rear view of the DC:

Pretty nice looking woofer overall with a very hefty cast iron basket and cosmetic attention paid even to the typically hidden magnet cover. The earliest models used silver hammertone paint. The Gold series used off-white paint and a gold magnet cover, the HPDs reversed this color scheme. You can see half of the Girdacoustic struts on the back of the cone; the other four are beneath the basket sections. The screws around the frame hold the metal and foam gasket to clamp the surround foam in place. The spider is also held in place by four bolts making the complete woofer assembly field replaceable.

Magnet cover label:


The somewhat unusual connection scheme that allows an easy to remove/install plug handling both woofer and treble connections:


Side view with magnet cover on:


Side view with magnet cover off revealing the 4” diameter slug of AlNiCo (they did not skimp in materials cost for this, built quality is excellent throughout):


Magnet and HF diaphragm cover rear view:


Regarding the sound, it’s difficult to give an accurate representation of what the drivers can do. Whereas Paul Klipsch is known to have called his company a ‘furniture maker’ as they excelled in building good cabinets for average drivers, Tannoy built excellent drivers and crammed them into mediocre boxes. The Berkeleys are constructed of ¾” particle board for the majority of the box with an extra layer in back of the top half of the baffle for the driver and a single board bracing baffle to back. While the fit and finish is very good, the panels regularly get to buzzing with stronger passages and add obvious coloration to the sound. As the box is also ported, the bass has a humped response in the “wow” region (50-80Hz) and has the typical ported sound, one note tubby sound with a sharp drop-out of much deep bass.

The lower midrange is depressed a bit in output and more than a little congested sounding to me, as is pretty typical of speakers crossing over around 1kHz especially those using larger drivers. This effect is fairly minor and I would likely have not noticed it so much had I not become accustomed to my Flatlines. However, as I had, this artifact is distracting and takes away significantly from the quality of sound as I’ve come to appreciate how important the midrange is to realistic sounding vocals and instruments. Part of this is likely contributions from cabinet vibrations that add a wooden, boxy sound to the midbass/lower midrange. Also, the crossover is stock and while the quality of the original caps was quite high, more so than the more typically used electrolytics of the day, they have likely gone out of spec and an upgrade here could improve this congestion and slight disparity in sound between the cone and horn.

As the frequency increases, the on axis output increases as well to a pronounced “honk” at just shy of 3 kHz and hole just above it. Due to the shape of the horn machined out of the bass driver’s pole piece, the tweeter would naturally have a nasty spike in response right here – something that would make for a severely fatiguing speaker as human hearing is most sensitive at this same frequency. To combat this, the folks at Tannoy added a notch filter to flatten the peak. (Later series used a tulip waveguide to counter the peak, but it came at the sacrifice of quality in the rest of the treble range, which is why the top model, the Westminster, uses a near direct clone of the HPD385A for its driver [with a different surround to maintain the foam’s benefit, but without the risk of rot].) The result wasn’t entirely successful making for a sharp rise and sharp dip immediately following. After this, the horn’s saw tooth response dominates, but the peaks and dips are less pronounced than a great many other horns of similar vintage. On axis, the treble is fatiguing for its steady string of peaks and dips and particularly for its rising response. However, when the listener sits 15 degrees off-axis as the Tannoy literature suggests, the response smoothes out and flattens a great deal making for a tamer sound. The rise is evident in this graph from a contemporary review of the Berkeley (the sub-70Hz is missing due to inadequacies with the anechoic chamber as mentioned in the review).



Despite these shortcomings, the overall sound quality is quite good. The Tannoys are surprisingly revealing and transparent for dynamic drivers and best vintage Magnepans in the lessened veiling. One of the areas where they excel is imaging thanks to the dual-concentric design that makes for minimal smearing of the soundstage thanks to the physical coincidence of the drivers and the phase coherency (though not time aligned). The optimal listening distance can be anywhere from 20 feet back to within a foot thanks to the lack of a need for the blending of output from disparate drivers. It’s no surprise that Tannoy DCs were the studio monitor of choice thanks to this and the overall quality of sound for the major label studios in Britain (interestingly according to Steve Hoffman, the Altec 604 was only used over there because the British studios desired to break into the American market and so chose the “inferior” Altec [all but the most recent series of 604s have a nasty upper midrange peak that makes the Tannoy honk mild in comparison] as that was what US studios were using). Once you hear Abbey Roads produced albums through Tannoys, you’ll suddenly understand that that’s the way the music is supposed to sound.

Another strong suit of Tannoy DCs is in the ability to well reproduce instrument body. The midbass regions are oft overlooked, but this is where the sonic size of a piano and the sound of a guitar body are to be found. The large cone allows strong transients here and make for a more realistic aural recreation. This is why these drivers are considered some of the very few dynamic drivers that can realistically recreate the sound of a piano to the point where the differences are indiscernible in an adjacent room and is something Hoffman emphasizes as a requisite for good sound. Also thanks to the large driver, the Tannoy DC is a strong non-horn performer for visceral impact with sharp transient response.

The Berkeley being rated at somewhere between 91dB/w/m and 95.5dB/w/m depending upon what literature you refer to allows for a wide choice in amplifiers. While this efficiency range puts them borderline compatible with SETs and the Sonic Impact, the large cone performs best with an amplifier capable of high current output. So, high powered (100-200wpc) solid state amplifiers tend to sound the best in my experience. Small tubes such as the 6BQ5, while having the power to provide satisfactory volume, simply cannot control the large cone and make for flabby bass with lousy transient response.

As is often the case in this hobby, a type of group think often develops among fans of some particular piece of gear or other. When this is combined with the general tendency of a portion of our number to believe that older and more colored is automatically more musical, more accurate and advanced models tend to be overlooked for their older variants. Such is especially the case amongst ‘Tannerds’. As such, Golds and older DCs are much more strongly sought than the more modern sounding, cleaner HPDs. For the budget minded hobbyist, this means that the 15” HPDs (essentially the same driver being used in Tannoys newest, most expensive TOTL offerings) can be picked up for less than the cost of smaller sized Golds and the like making for an awesome bargain. A set of 15” HPD385As in great shape can be picked up for ~$800 with cabinets. If the foam is rotten, the price can be lower thanks to a misconception that there are no appropriate refoam kits available for this driver. Speaker Bits in Australia claims to be the only supplier of the appropriate kits for the Scottish built speakers and sold the surrounds in the past for a whopping $270/pr, but prices seem to have dropped appreciably. Most Tannerds are under the illusion that anything else just won’t work. With a little searching, the same fit and quality replacement surrounds (HPD surrounds are tear drop shaped in cross-section, not half-round, have a special angled lip, very flexible, and are an odd size) can be found for $30 at places such as Audio Atlanta giving the impoverished audio enthusiast an advantage over those who would believe the myths.

If you’re the least bit handy and can built a set of thick walled, reinforced cabinets, the HPD series is a relatively affordable way to get sound on par with tens of kilobucks speaker systems for under $1000.

- JP

I'd really like to hear those some day. Nice writeup.

- Have you heard the Altec 604's? Is there comparisons or are these a lot different?

K

I've not yet had the chance to personally hear the 604s. However, there are graphs showing their response on the internet seeing how both saw widespread use as studio monitors. I've read more than a few comparative reviews between the 604s and Tannoys. Steve Hoffman has made a point to discuss why the Tannoys were more accurate monitors compared to the spiky response of the "inferior" (quoted) Altecs. Oh, I also had the chance to spend ~3 hours total over several phone calls discussing and comparing Altec A7-500s, 604s (of varying series), and Tannoys with a gent (who bought my Altec drivers) up in Bellingham who's one of the guys who upgrades old Altecs and helped design his company's own new series of 604 soon to be released where they made it their primary objective to cure this peak and associated faults. I learned a lot about coaxial speaker design and Altecs in general through those and the difficulties in overcoming the weakness of the original 604 design and how much better the most recent variants sound compared to the old.

For comparisons, the 604 was a separate compression driver feeding a regular horn bolted onto the pole piece of one of their 15" woofers. There's a fair bit of interaction between the wavefront from the cone at the upper frequencies with the big hunk of metal sitting in the middle of it. Plus, the disparate drivers bring some of their own issues to the table. As you can see, the Tannoy DCs were designed such that both drivers were integrated (the woofer is the treble's horn and the motor is partially shared) with one another to smoothly transition from one to the other. However, the Tannoys do suffer some Doppler distortion when high output and thus excursion comes into play, which is another reason why the 15"ers are preferred over the smaller models as the cone moves less for a given output making this distortion negligible.

Still, I'll say that the Tannoys outside of their big horn enclosures are not the last word in fidelity and aren't wholly deserving of the blind loyalty they've garnered.

- JP

i'd like to add my, albeit non-technical, take on these speakers.

JP's pair are the only Tannoy's i've ever heard, they were being driven with his T-Amp, and it was only for a short while. even so, i was immediately struck by their over all "well-rounded" sound. even after JP explained, in great detail, where the speaker fell short, i could'nt find any shortcomings in the sound.

this speaker met all my criteria, it is very well balanced with a high order of clarity, detail and refinement. all in all a very good speaker.

great pics JP!!

as far as the write-up, not too sure what that all means soundwise, but, see if you can find a pair of Electrohome PA100Mk1's to power them badboys!

What a great review.
Lots of info. One of the best speaker reviews i ever read in years....
Many thanks for this work of art review statement. Really, i do not know many forums like our forum... in so many areas concerning sound and hi-fi.
Your review move me in a very emotional way. Tanx.