Monitor Audio Gold 300 loudspeaker

About a year after settling into my new house, I decided to buy a pair of Monitor Audio Silver 10 floorstanding loudspeakers, which I had reviewed in 2014 for our sister publication Sound & Vision. I wound up buying three of them, with the intention of cannibalizing the drivers and crossover from one to make my own three-way center-channel speaker. But that project was long delayed, and I never got around to doing anything with the third Silver 10: It now sits in a closet as a spare. (The similar but smaller Silver 8 and its replacement, the new Silver 300, were both reviewed for Stereophile by Kal Rubinson, footnote 1.)

In any event, the Silver 10s have been my reference for the past three years, despite being superseded by the Silver 500s in Monitor Audio's most recent Silver line. But there are usually other loudspeakers in for review—an occupational hazard in my line of work—and when that happens, the Silver 10s are set aside.

This time around, the "other loudspeaker" is the Silver 300's big brother, the new Monitor Audio Gold 300 ($7000/pair). It's the flagship of Monitor Audio's Gold line—now the fifth generation of Golds, all models of which have been extensively upgraded. All of the Silver and Gold models were designed in the UK and are manufactured in China.

Design
The Gold 300 is a three-way design employing a pair of 8" woofers, an unusually small, 2.5" midrange, and a 1" folded "ribbon" tweeter that isn't technically a ribbon: Monitor Audio calls it a "Micro Pleated Diaphragm," or MPD. It's a brother to the Air Motion Transformer (or AMT) invented in the early 1970s by Dr. Oscar Heil. Variations on this design, most far smaller than the original, are now widely used in commercial speakers, though it's still far less common than conventional dome tweeters. The design's benefits are a largely resistive load, no significant inductance (dome tweeters have an inductive voice-coil that complicates crossover design), and low mass, the latter despite a surface area that, in this case, is six times greater than that of Monitor Audio's own 25mm gold-colored dome tweeter.

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At barely an inch square, this MPD is one of the smallest tweeters of its type I've yet seen. That isn't a criticism; the smaller the tweeter the wider its dispersion, though this is generally counterbalanced by a reduction in its power handling, thus a need for a higher crossover frequency. To further enhance dispersion, as well as provide a better match at the crossover point to the midrange, Monitor's MPD tweeter is mounted in a shallow waveguide.

Located just below the tweeter is Monitor Audio's new 2.5" midrange driver with a C-CAM cone. C-CAM (Ceramic-Coated Aluminum) has been used in Monitor Audio's designs for several generations. This is the smallest non-dome midrange driver I've ever seen on a speaker. Its claimed linear excursion is ±1.5mm, with a cone breakup two octaves above the crossover point to the tweeter.

The tweeter and midrange are spaced close together on their own aluminum sub-baffle, sealed from behind in an aluminum chamber isolating them from the back pressure of the Gold 300's two 8" woofers. The latter employ Monitor Audio's RDT II (Rigid Diaphragm Technology II) cones, a sandwich construction consisting of a C-CAM front, a woven carbon-fiber back skin, and a Nomex honeycomb core. The combination is said to offer stiffness, light weight, and good damping—and so the dimples used to reduce resonances on the Silver series drivers are apparently not needed. (I sort of miss those dimples here; their golf ball texture offers a unique look that's missing from the new Gold's smooth cones.) Pressure behind the woofer's cones is relieved by holes in the voice coil former—Monitor Audio's Vented Driver Technology (VDT). The magnet structure is vented as well, and the motor assembly has been optimized with Finite Element Analysis (FEA—try to keep up with the acronyms!).

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The drivers are connected via a crossover network using premium-grade polypropylene capacitors and a combination of air-core and lossless steel-core inductors. The crossover points are 650Hz and 3kHz, the slightly-higher-than-typical latter frequency made possible by the small midrange driver, which makes the tweeter's job a bit easier. The filter orders/rolloff rates aren't specified.

As in many Monitor Audio loudspeakers, a threaded rod is fastened to the rear of each woofer; these extend through openings on the cabinet's rear panel, where they are secured on the outside by large, decorative nuts. This not only eliminates visible mounting hardware on the front but also provides increased bracing. Not that the latter's in short supply: The cabinet's 18mm MDF walls are extensively braced.

Two HiVe (high velocity) reflex ports are around back; foam plugs are provided to block them if desired (I didn't). Two pairs of input terminals offer biwire or biamp options. For single-wire/single-amp use, the Gold's terminal shorting links are wire rather than the usual solid metal straps. The cabinet's sturdy outrigger feet can be used with or without spikes. As is increasingly common, the provided spikes are neither long enough nor tapered sharply enough (likely due to safety concerns) to penetrate a carpet.

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While the Gold 300s are no larger than my Silver 10s (not counting the two models' outriggers/plinths), they're significantly heavier. They're also available in four finishes, with tops covered in a soft black leatherette. Our samples were Piano Gloss Black, but if I were buying, I'd take a close look at the Piano Ebony (woodgrain) before deciding.

Setup
The area of my listening space is 16' by 21' with an oddly sloped ceiling at an (estimated) average height of 9'. But the entire right side opens into adjoining spaces, making the acoustic volume the system sees much larger than just the floor dimensions of the room itself. The room is also used in my work for Sound & Vision and is equipped with two projection screens, but they're fully retracted when music is the main event. A flat-screen TV sits between the speakers, but it's positioned well to the rear of the plane of the speakers, and its reflective screen is covered by a small blanket when needed. Most of the floor area is covered with large, thick, unpadded rugs. Books, CDs, and videos cover the back wall on high shelves located several feet behind the listening seat.

The system for this review included a Marantz AV8805 surround-sound processor (limited here to two channels only). This was connected to two channels of the five-channel, John Curl-designed, class-AB Parasound Halo A 52+ amplifier, rated at 180Wpc into 8 ohms with five channels driven (or, more applicable here, 350Wpc with two channels driven into the 4-ohm-specified Gold 300s). The pre-pro and source, the latter a Marantz UD7007 disc player, were connected to the mains via a Tripp Lite Isobar 6 surge suppressor; the amplifier was connected directly to the wall outlet. All of the (IEC) power cords were generic. The Marantz player was connected digitally to the Marantz pre-pro with a Kimber AGDL cable. Unbalanced, vintage Cardas Hexlink interconnects ran from the Marantz pre-pro to the amplifier.

Instead of the AudioQuest Rocket 88 speaker cables I normally use, I switched to a pair of QED Silver Anniversary XTs that haven't seen action here in years, and even then not for long. When I first tried them way back when, in a different house and room, I found them a bit lean. But that quality balanced nicely in this room and with these speakers. The QEDs also use the tightest-fitting banana plugs I've ever experienced. Contrary to their name, the Silver Anniversary XTs don't use silver wire but are simply high-purity copper. And they aren't at all pricey; I'm not a fan of cables that cost as much as, or more than, the speakers they're connected to. (With cables we're talking about subtle system tuning, regardless of their price, not sound changes from another world.)

I set up the Gold 300s about 9' apart and angled them inward to face the listening seat roughly 8.5' away. This is about 2.5' nearer than I've typically used in the past; recent experimentation, including measurements, has shown that this closer listening position resulted in more precise imaging and a smoother (but no more extended) bass response. As with all my speaker reviews, the Gold 300s were located roughly 3.5' from the bay-shaped walls behind them. While the left speaker had a full wall about 4' from its side, the right side of the right speaker did not; it was fully open to another large space adjoining the listening area.

COMPANY INFO
Kevro International
US distributor: Monitor Audio USA
902 McKay Road, Suite 4
Pickering, ON L1W 3X8, Canada
ARTICLE CONTENTS

COMMENTS
beave's picture

From the review: "The design's benefits are a largely resistive load, no significant inductance (dome tweeters have an inductive voice-coil that complicates crossover design)..."

From the measurements: "...the phase angle exceeds +40° above 10kHz, presumably due to the inductance of the MPD tweeter's drive system."

JRT's picture

Air Motion Transformer tweeters exhibit flat resistive impedance response with respect to frequency in the audible frequency range. Not sure about impedance a decade or two higher.

Look at the data sheets of the Dayton Audio AMT series of tweeters.

http://www.daytonaudio.com/index.php/loudspeaker-components/loudspeaker-drivers-by-series/amt-series.html

beave's picture

That's what the review says.

But the measurements show a significant phase angle in the impedance in the highest frequencies.

Bogolu Haranath's picture

That significant phase angle you are mentioning (above 10 Khz) is not the region of the cone upper midrange frequency ........ It is in the MPD ribbon tweeter frequency range :-) .........

beave's picture

My post referenced the tweeter, not the midrange.

JRT's picture

I'm not sure what they might be doing in the crossover in the tweeter's filter network to clean up the tweeter's wave guide response, and what they might be letting happen in the ultrasonics to reduce component count. It does seem to exhibit a high Q low pass rolloff in the top octave, the high Q peak providing a little lift and associated rininging, the peak visible in figures 4 and 5. The associated peaking filter in that top octave shows as a sag in the rising impedance curve in figure 1.

edit: It was pointed out to me that JA1's measurements include some resonance present in the top octave in all of his loudspeaker measurements, and that seems to be obfuscating the behavior of the low pass here.

Bogolu Haranath's picture

There is a little peak at appox. 16 to 18 Khz region in the frequency response, but it is not anything significant ........ I have seen worse 'oil can resonance' peaks and dips in the frequency response of some metal dome tweeters ....... But those peaks and dips are usually above 20 Khz :-) ......

JRT's picture

With exception of a slight psychoacoustic dip in the range of 2kHz to 4.5_kHz, the response appears to be within a few dB of nominal above the baffle edge diffraction step and associated correction.

Bogolu Haranath's picture

That is the famous 'BBC dip' in that frequency ....... But that dip is not much in this speaker ....... Usually that dip is purposefully engineered to be -5 db or more :-) .......

JRT's picture

Psychoacoustic dip at the link:

https://www.linkwitzlab.com/models.htm#H

Bogolu Haranath's picture

Yes .... Your reference mentions the name 'H.D Harwood, BBC research department 1976' ....... Anyway, that dip is popularly known as 'BBC dip' :-) ........

beave's picture

I see a similar response in the datasheets for the drivers you linked to previously from Parts Express. I think it's inherent in the driver.

But I don't see any ringing in figure 9. Isn't that little black slice always there in JA's plots and something he has mentioned as being the line rate of his monitor?

JRT's picture

...for pointing out the issue of the monitor.

Bogolu Haranath's picture

Also, that significant phase angle is not in the crossover region between upper midrange and MPD tweeter, which is 3 Khz :-) .........

JRT's picture

Look in the top octave, not the crossover frequency. They are shaping response up there.

Bogolu Haranath's picture

True ..... There is significant drop-off of FR, say from above 18 to 19 Khz ....... I don't know whether that makes any significant audible difference ...... Look at the TJN's in-room FR measurements ........ There is a lot of drop-off of the FR in the top octave :-) .........

JRT's picture

If the high frequency low pass response exhibits high Q, then the associated peak near the corner of that low pass would provide some lift in the response, and there would be some ringing associated with that.

Note that graphics show eight curves while the keys at the bottom of each identify nine. Regardless that error in identifying curves, the graphics are good enough to show Q affecting peaking and ringing. The brown curves look like textbook 2nd order Butterworth (Q=0.7071) and the yellow curves look like textbook 2nd order Linkwitz-Riley (Q=0.5000).

Source of graphics: https://e2e.ti.com/blogs_/b/analogwire/archive/2015/06/12/is-your-op-amp-filter-ringing-look-at-q

edit: It was pointed out to me that JA1's computer monitor causes a problem that falsely shows some resonance present in the top octave in all of his loudspeaker measurements, and that seems to be obfuscating some of the behavior of the low pass here.

beave's picture

Again, as mentioned above, hasn't JA said that it's an artifact of his video monitor?

JRT's picture

I do appreciate that you pointed that out to me, but did not see your comment before this morning. My comment has been edited to reflect that problem associated with the monitor. I would not want to mislead anyone with erroneous observations.

Bogolu Haranath's picture

BTW ..... Hi-Fi News has reviewed the Monitor Audio Gold 100 bookshelf/stand-mount speakers (EISA award winner) which probably use similar type of tweeters ....... Hi-Fi News measurements show similar type of peak around 15-16 Khz, with a sharp drop-off of FR above 20 Khz :-) ........

Bogolu Haranath's picture

If you want to see how 'oil can resonance' looks like (which I mentioned above), see the Hi-Fi News measurements of KEF R11 (EISA award winner) ......... But, those peaks and dips are way above 20 Khz ...... KEF is one of the companies, which uses Aluminum domes for tweeters :-) ........

Bogolu Haranath's picture

Another example ...... There seems to be some type of filter being used for high frequency roll-off for the GoldenEar speakers ....... GoldenEar also uses ribbon tweeters ....... Look at the FR measurements of GoldeEar Triton Reference by Hi-Fi News ......... There is a sharp drop-off of FR above 20 Khz :-) ........

Bogolu Haranath's picture

Here comes the 'king' of all FR measurements ......... See Hi-Fi News measurements of Dali Callisto 6C ...... Nice 'BBC dip' in the presence region and a sharp drop-off above 20 Khz ...... Very 'dramatic' FR :-) ........

Bogolu Haranath's picture

Interestingly TJN used +1 db boost in the treble frequency :-) .......

JRT's picture

Its a subjective choice in voicing the crossover.

Bogolu Haranath's picture

Goes to show the usefulness of tone controls/EQ :-) ........

JRT's picture

Al₂O₃ aluminum oxide, aka Corundum, aka Alumina ceramic, and in single crystal natural gemstone or synthetic is Ruby and Sapphire.

Al₂O₃ is also the surface coating result of aluminum anodization.

https://sundoc.bibliothek.uni-halle.de/diss-online/04/04H055/t2.pdf

MIL-A-8625
Type I chromic acid anodizing
Type II sulphuric acid anodizing
Type III sulphuric acid hard anodizing

There are processes that can produce a significantly thicker anodize, and some might refer to that as ceramic coating. It probably sells better than anodized aluminum. The Alumina ceramic is more rigid and more brittle than the aluminum substrate. It is more difficult to get a consistent thick layer of Alumina on a thin substrate of aluminum of a controlled shape without breaking the resulting item, because it can be fragile. Ask anybody who suffered through breaking an Accuton diaphragm, not inexpensive.

https://accuton.com/en-home/produkte/lautsprecher/keramik

Bogolu Haranath's picture

Revel is one example company, which uses DCC (deep ceramic composite) Aluminum cones :-) ........

Bogolu Haranath's picture

Additional note ........ The Beryllium dome tweeters used in Revel speakers show almost flat frequency response to 20 Khz :-) ........

Bogolu Haranath's picture

Time for Stereophile review of Polk Audio Legend L800 floor-standing speakers, with SDA technology ..... About in the same price range, $6,000/pair ....... See S&V review :-) .......

ringmeraudioguy's picture

I don’t understand the above commenters, seemingly trying to show their knowledge of test results and exhibiting blatant, ‘I know better than you’ statements. Such pedantry is boring. Just listen to the music!!

Chris Gramer's picture

These "Monitor Audio Gold 300" speakers look markedly different than those being sold by Crutchfield. Does MA reuse model names for multiple generations of speakers?

Example:
https://www.crutchfield.com/p_893G300PB/Monitor-Audio-Gold-300-Piano-Black.html?cc=07&tp=185

Just wondering. Thanks!

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