I am just a bit obsessed with vintage Yamaha amplifiers

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Sometimes I talk about things other than cars and gaming. Here is my current obsession with vintage Yamaha amplifiers such as the CR-800 and MX-1.

1972. The year of the final Apollo mission, Watergate Scandal and the premiere of Pink Floyd – The Dark Side of the Moon at the Dome in Brighton. After a technical hitch that meant everyone had to wait a day to hear the album in its entirety.

It was also the year Yamaha started selling integrated amplifiers, first of which was the CA-700 (CA short for Class A). With musical instrument expertise hard-wired into its DNA, the resulting trademark ‘natural sound’ made sense.

How would I describe Yamaha audio presentation? Verging on bright (sometimes too much with some speakers). Musically accurate. Detailed. Involving. Flat in EQ. Though not instantly loveable, it can be hard to go back to warmer competitors.

My journey into HiFi started with Pioneer, Technics and JVC, the makers of the HiFi separates I inherited from my late grandfather. Those dark wood mid-range JVC bookshelf speakers may not have been top of the range, but they sure did belt out a great sound. From home to barn parties – Somerset upbringing for the win – they were fabulous.

Without sounding a bit old and millennial (both true), it is sad knowing that many music fans only ever use low quality headphones and speakers. Even a cheap charity shop HiFi setup from decades ago can provide a wonderful sound and look great.

Vintage Yamaha amplifiers in particular, with their silvery boxes of audio encased in wood (solid or veneer), look timeless. I would hazard a guess that pleasant aesthetic helped ensure proud owners took care of them.

It is also no coincidence that its more recent offerings such as the A-S501 and cheaper A-S301 have stuck with big, smooth-operating dials, chunky switches and flat metallic surfaces. Black as opposed to silver, mind you.

Yamaha-ppy

It was on What HiFi‘s recommendation that in 2011 I purchased a Yamaha A-S500 (superseded by the A-S501). Paired with Tannoy Mercury V4 floor-standers, it really was (and still is) a great performer for the money.

The resulting sound did not shake the room to bits. By being reserved and accurate with the lows, however, they felt that much sweeter when delivered. You could listen to this setup all day with zero ear fatigue.

Rolling on to 2024, I dug out the Yamaha A-s500 and connected it to an Asus Xonar Essence STX sound card (the ST version does not play nice with PCI-E slots). I then bought some black KEF LS50 speaker from deepest, darkest Wales.

An audio soundcard, you say? Before you complain, I spent two days going A to B between the Xonar Essence STX and original Chord Mojo. At this level of HiFi and with a variety of audio sources, both sounded identical.

Now, those uniquely styled LS50 speakers have a cult following. Mine are the original design, which reviewed favourably. But they were replaced by the slightly superior Meta version and then the LS50 Wireless I and II, which have two powerful in-built amplifiers.

Some have criticised the LS50 sound as bright and lacking in bass. The reality, though, is that – like Yamaha amplifiers – the sound is accurate, exciting and not always flattering if the source is low quality. But to say there is no mid-range or low-end is a user error issue and most music sounds glorious.

What I would say is that the 85-watt Yamaha A-S500 can power the difficult-to-drive KEF LS50 (85dB speaker sensitivity versus 91dB for the Mercury V4). However, I wanted to see why KEF went with two amplifiers for the LS50W – a 280-watt class D and a 100-watt class A/B.

So I purchased another two vintage Yamaha amplifiers. First came the admittedly weaker 1974 CR-800, acquired during those oh-so-fun lockdowns. It looks fantastic, pumps out 45 watts at 8 ohms and is uncharacteristically warm for a Yammie.

Some say it is one of the best-sounding Yamahas ever. While I cannot confirm or deny that bold claim, I am curious whether it has ever been serviced. If not, inside are 50-year-old capacitors, transistors, relays and solder joints. With some work, it would probably sound even nicer.

Unfortunately, there is some crackling and static in the background. There is also a pop when turning it off, which is likely (and hopefully) down to a dirty protection relay. The plastic cover looks tarnished and the metal contacts are brown. It can also be because of blown bulbs, all four which are sitting on my desk ready to be fitted.

That is why I bought a replacement Finder 55.12.9.012.0000 from eBay (alternatively, the MY2-02-DC12). Due to the fact the protection relay is oriented sideways inside the CR-800 and has a tight-fitting cover, desoldering and removal is best for a repair.

Supposedly, there is a tool you can make to remove the troublesome plastic housing. In doing so, I would be able to use card/sand paper and Deoxit contact cleaner. However, given the age I shall start afresh and get busy with my new Miniware TS101.

Deoxit for the win?

While learning how to solder without causing a major fire and third-degree burns, I set about cleaning switches and potentiometers (pots for short). Servisol 10 was my go-to in the past, which did okay.

This time, I thought I would try much pricier Deoxit D5. Just a quick spray, work the switches and dials then let it dry. To finish, an additional blast of Deoxit F5 Faderlube on the pots to ensure lubrication of those moving parts. Some say D5 can be a bit harsh on its own.

Annoyingly, Deoxit D5/F5 does not come out well using the supplied red tube, but I suspect it will last years. Just aim it in the pot holes (not of the tarmac variety) and keep some kitchen roll or a microfibre cloth under to catch wayward drips.

Upon powering on the CR-800, the pesky background static was still present. I need to confirm whether both speaker connections do it or it is a global thing, as this will help me narrow down the issue if it is not the aforementioned protection relay.

Removing the associated PCB is easy as two comically long screws hold the heatsink in place. There are, however, various cables at the bottom that are short and un-pluggable. I should have better luck with the heatsink detached.

Welcoming the MX-1 and CR-800 vintage Yamaha amplifiers

Following on from the CR-800, I purchased a Yamaha MX-1. Nothing to do with motocross though Yamaha does also have that pedigree. Why? Because I wanted to see how much of a difference it would make, if any, to the LS50 speakers.

If you think of the CR-800 as a grenade and the A-S500 as a bomb, the MX-1 is nuclear fission. This ugly unassuming 24kg Japanese monster may only have three buttons, but it is an absolute audio weapon.

It can drive 200 watts into four speakers at 8 ohms, with a frequency response of 20Hz to 20kHz. Total harmonic distortion is 0.008 per cent, while the signal-to-noise is 125dB.

Where the Yamaha MX-1 differs from most amplifiers, particularly newer stuff, is that it can drive speakers at both 4 ohms and 2 ohms. The former getting 260 watts and the latter 320 watts. Enough to power just about any home speaker.

In short bursts, there is enough headroom to melt your face with 1,200 watts. No wonder it weighs a ton. This is mainly because of four heavy duty capacitors, twin-transformers, chunky metal construction and damping material upon which everything else is mounted.

Being a Japanese import means I had to order a sizeable step-down power transformer (from 230V to 100V). Most options in the UK are specced for 110v (10 per cent more than necessary). Hence why I had to go with one from Airlink.

Power to the power amp

Specifically, a pricier version to incorporate an isolated design and 2,000VA to keep the MX-1 happy. Codename: UK-JA2000-ISO.

When all 12.7kg of transformer arrives I shall be comparing three generations of Yamaha amplifier using my Tannoy Mercury V4, KEF LS50 and Mission LX-2 speakers. Will the MX-1 blow everything else out of the water? I am curious to hear.

In the meantime, I shall focus on the CR-800. Maybe the MX-1 will also need some repair loving though I was told it has been serviced since its release in the early 90s and no capacitors look ready to leak.

Suffice to say, I will be purchasing an ESR meter, multi-meter and probably some other testing equipment to see (well, hear) the lay of the land. Farewell, precious spare time.

Yamaha A-S500 vs MX-1

When the Yamaha MX-1 came out, it was towards the tail-end of the HiFi heyday. Consumers were changing their tune about two-channel stereo and sales were not as impressive as they used to be. Production lasted a decade, but it was never given the marketing boost of its predecessors such as the MX-2000, MX-1000U or even the ultra-rare and legendary MX-10000.

But the MX-1 was no afterthought, as the specs I mentioned earlier show. It was built to power just about any home speaker effortlessly, regardless of the rating. HCA, short for Hyperbolic Conversion Amplication, is said to give you up to 30 watts of Class A amplification without the associated heat and power consumption.

I am unsure if many people could differentiate Class A and Class A/B, let alone afford the equipment where you might be able to. But I have hooked up my LS50 speakers to the MX-1 and first impressions are great.

But first, connecting straight to my Asus Xonar Essence STX sound card has one minor issue. With the MX-1 gain at maximum as recommended in the manual, maximum sensible volume is about 30 in Windows 10. A pre-amplifier such as the CX-1 or CX-2 would be lovely, but unfortunately I am not made of money.

Anyway, the MX-1 started up without any fuss and the Airlink transformer it is connected to does not make any noise or audibly affect the sound. Not sure it will any design awards though, but reliable and clean power is the aim and it seems to deliver.

How does the MX-1 sound compared with the A-S500? Well, I will say that the MX-1 was considerably more expensive at launch (the somewhat weaker MX-2 would be more comparable) so there are a few things that come to mind. One is that the A-S500 really does kick butt for the money. The difference is not really night and day.

The AS-500 is clear, precise and has some bass slam. Its 85-watt output enough to get a strong performance out of the LS50s. But with the MX-1, the bass is a little tighter, stronger and there is greater mid-range punch. I would hazard a guess the LS50 speakers, not built as a party speaker, are perhaps not best to highlight the massive output difference of the two amplifies.

What else comes to mind is the Yamaha sound is consistent across the decades and that to have top-end performance of times gone by for a few hundred dollars really is amazing. Amplifier technology improvements do make the modern stuff hard to beat though there are still many vintage and later bargains to be had.

Anyway, I still have many songs to listen to using the MX-1. So far, I am happy but I shall need some more ‘scientific’ A/B testing to make a more informed decision. Maybe those extra watts will be more noticeable through the Mercury V4 floorstanders.

To be continued (I will update this post as I go)…