Tannoy Monitor Gold 15″ (LSU/HF/15/8) were on my wish list since I discovered coaxial speakers and the theory behind putting two drivers on one axis. Couple of years ago I have become a lucky owner of these beautiful drivers. They were bought from London, from the first owner who in 1968 bought them in Lancaster enclosures. The gentleman used them in his private recording studio for couple of years during 70s. Afterwards, drivers were taken out of the enclosures, with an intention of building better enclosures. This has never happened, and for over 30 years these drivers were waiting for me in storage.
When I first plugged in these monster drivers in hardly optimized test cabinets I was very impressed with their sound. And this was done using crossovers with old electrolytic capacitors. Many hours of soldering and even more hours of wood working after, and I was able to test these drivers with crossovers based on very good quality components and in heavy, sand filled, 25mm thick plywood, 210l bass reflex enclosures. More about building of these can be found in DIY section of this page.
As you gathered by now, I bought these drivers without any enclosures so I was not able to review any particular model of vintage Tannoy speakers that use Monitor Gold drivers (for instance Lancaster or York). Nonetheless, from what I have heard, Tannoy enclosures from the basic range are not very rigid and people who buy them, sooner or later replace them with better quality DIY cabinets. Having heard Tannoy Monitor gGld drivers in many different closed and bass reflex enclosures, I am confident that enclosures used for this review allowed the drivers to show their character and basic sound qualities.
Tannoy Monitor Gold 15in are the largest (and most expensive) drivers in the Monitor Gold range. The “Monitor Gold 15” is a common name, but their factory model name is LSU/HF/15/8. They were are successors to Tannoy Monitor Red 15, and were first launched in 1967. The reviewed pair is from 1968, therefore, from the second year of production. These drivers feature unique ‘Dual Concentric’ construction (visible on the scan of the sales brochure above), which ultimately means that we have two drivers (tweeter/bass) combined in one driver and working on the same axis. This itself would not be so unique as there are many other coaxial drivers out there, however, in Tannoys, the tweeter diaphragm is placed behind the driver’s magnet and the same magnet is used to power both – the bass and the tweeter diaphragms. Furthermore, the tweeter diaphragm is positioned in inverted phase. The airwaves produced by it travel through the PepperPot phase plug, and then, they are ‘acoustically amplified’ in the metal horn throat (inside the magnet) and finally ‘amplified’ further by the bass diaphragm, which acts as a horn extension. Horns can usually be fond in the PA speakers, however, there are number of HiFi manufacturers that use horns with very good results (e.g. Klipsch, JBL, Altec, Lowther) and Tannoy is one of them. This is a rather basic description, but it gives a good overview of how these drivers work. People who are into DIY may find it strange, that a heavy paper cone (LF unit) is crossing over with the efficient HF unit at 1kHz, as this contradicts with best practices that can be found in many speaker building books. But, it works, and it works rather well! Having two diaphragms on one axis (in theory) should result in better pin point imaging than in traditional speaker designs, as the whole frequency range originates at one point source of sound, not from two or three different drivers placed somewhere on the speaker face.
Couple words about their history… Tannoy Monitor Gold range was very popular in the recording studios, in 1970s. Many famous studios (including Abbey Road in London) used these speakers for mixing – check the photo of the right, found somewhere on the internet – pair of Tannoy Lancasters, presumably with MG15 inside. Numerous legendary albums were mixed using these speakers, so if you have a pair at home, you may be hearing the recording in a very similar way to the person who mixed it (this isn’t always a good news though ;). Also, I have found something that indicates that some of the recording studios may have been using these speakers in more modern times. The photo on the left is an inner front cover of the Marchin’ Already album by Ocean Colour Scene. Looks familiar? Recording was made in 1997. Apart from studio monitoring, these drivers were also used in higher end of domestic market. They were used in large horn loaded enclosures like GRF, GRF Professional and Autographs.
|Frequency Response:||23 – 20,000Hz|
|Impedance:||8Ω (5Ω min.)|
|High & Low Frequency Driver:||LSU/HF/15/8 380mm (15″) Dual Concentric with 51mm (2″) Aluminium Dome Compression Driver and 380mm (15″) Paper Diaphragm|
|Free Air Resonance (FS):||26Hz|
|Weight:||10kg (each driver)|
|Price When Launched:||£84 for a pair|
|Equivalent Present Day Price:||£1,380 for a pair|
|Current UK Price:||£1,300 to £1800 for a pair|
Look & Feel of Tannoy Monitor Gold 15″
These drivers, 46 years after they were made, still look very impressive. The baskets are made from a very rigid die cast alloy and are stove enamelled. Diaphragms are made form paper. Interestingly, the diaphragm suspension is an extension of the actual diaphragm (paper) and it is coated with rubbery looking substance, presumably to aid with cone termination and to tune resonance frequency to the desired level. The throat of the horn is made from untreated metal, which when mixed with humid British weather, often results in minor oxidation on the throat surface. The motors are rather large alnico magnets hidden under gold plastic covers. The crossovers are nicely soldered, using components available at the time when these were made. Wires and plugs are rather low quality by modern standards, however, they were probably OK back in the day. Overall, despite the pitfalls, really impressive drivers. Playing with these drivers was like playing with an old Jaguar E Type – classic beauty. Photos below present the drivers after the upgrade of plugs.
Sound of Tannoy Monitor Gold 15″
When plugged in for the first time they were very overwhelming – in a good way though. The presentation of the sound is very different than in the traditional speaker constructions. First thing that I noticed was the soundstage. It was like a massive wall of sound. The soundstage was still there, and I was able to separate the instruments, etc., but the sound was never coming from 10 meters behind the speakers, so not much soundstage depth.
The Tannoy Monitor Gold drivers are very fast and dynamic and when compared with a lot of modern speakers, this can be very nice. Feeling the physical impact of the sound is not something that people are used to these days, especially people who use stand mount monitors for playback. Bass is never floppy or boomy and always stays under control. And it goes deep, very deep. Even at 35Hz using signal generator you can clearly hear the sound.
Midrange and treble sound very good indeed, being very sweet and easy to listen. Saying this, the MG15s are not the most detailed speakers in the world. They are many more speakers that are more detailed and provide better separation, but there are not many speakers that deliver full bodied sweet sound that these Monitor Golds do. What they do best is saxophones (I have never heard Ben Webster’s My Romance sounding so realistic on any other speakers), double bass (Temptation by Diana Krall sounds mind bowing) and vocals, although some of the higher sections may sound a bit edgy – like Tears Behind My Eyes by Spooky Tooth. Where these speakers struggle, is when depth of the soundstage and separation play important role in the track – try Eric Bibb – Needed Time or Chris Rea – Auberge. And don’t get me wrong, they will still sound fairly detailed and easy to listen, however, they are other speaker within this price range that can deliver much deeper soundstage imaging. They are also not the most truthful presenters – there is a degree of sound colouration. But, don’t be put off by this as this is part of their character and part of what makes them special. To me the most important factor when listening is enjoyment and engagement, and these drivers can certainly deliver both.
Regarding amplification, many people (probably due to relatively high sensitivity of these drivers) suggest using them with valve amps. From what I have read, these drivers were designed with transistor amps in mind, hence their 8 ohm nominal impedance. I’ve tried them with both valve and transistor amps and I much prefer their sound with good transistor, mainly due to better dynamics and bass control.
Tannoy Monitor Gold driver are very musical and easy to listen. No the most detailed, and the soundstage depth is far from ideal, but despite these pitfalls, very enjoyable to listen. Overall, sweet sound, with a lot of kick and energy to it.
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