Intriguing Luxman MQ60 valve amps on ebay....

pmcuk

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https://www.ebay.co.uk/itm/115983484809 Cheapest at £850, and might take an offer.

Luxman amps have a wonderful reputation - very fine output transformers. They were thousands new. The problem with this model is that the output valves are Matsushita 50CA10 triodes running off 50V heaters. There is data on Franks site including curves. But these are uber rare and silly money and the reason why several of these amps are up for sale.

https://frank.pocnet.net/sheets/084/5/50C-A10.pdf

Good YouTube video on it



I'm intrigued by these amps. If I got my itchy fingers on one I would first listen to it for a while and then swap the output tubes for something more common like 6V6, 6L6 or EL34 in triode. I'd be tempted to use EL12n valves in triode myself. They would need a 6.3V supply but that could be outboard in a box.

Even better would be push-pull 2a3 valves if a pair fitted width-wise. Output transformers are 5K. The other thing that has to be done is to use an external step-down transformer since Japanese voltage is 100V. The mains transformer could be swapped for e.g a Hammond model but much cheaper to avoid that.

I actually have a mains transformer for push-pull 2a3 valves that would be a perfect replacement, and that would be a super duper amp. If anyone is interested in such a project let me know and we can arrange a very favourable price for it.

A bit of modification and you would have a seriously nice valve amplifier indeed for under £1,000. Couple of others in the UK priced at £1,200. I'd be interested myself except that it would be too heavy for me to work on these days.

Luxman MQ60.jpeg
 
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bencat

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Anything running 100v is a No for me plus these were Luxman Kit amps DIY made from Luxman parts .
 

pmcuk

Wammer
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Sep 12, 2015
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Kensington, London
HiFi Trade?
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Anything running 100v is a No for me plus these were Luxman Kit amps DIY made from Luxman parts .
There's loads for sale, mostly in Japan. Some of these were kits named KMQ-60 and some were factory made named MQ-60. This £850 one is just marked "Custom" and looks like it's factory built - very neat wiring. Or a good builder.

Very good transformers so I think it's worthwhile keeping them and making a second outboard box which would sit just to the right of the chassis with the 230-100V step-down and also a 6.3V supply, basically just a 6+6V toroid to supply the heaters of the EL34 output tubes, which look like the best choice in triode for a 5K PP OPT. 4 way umbilical which could use e.g. a 4 way Speakon to connect to the outboard supply.

This wouldn't be much work at all, make the outboard box and change the 4 sockets to octals for the new output tubes. The operating point of the original output tubes would be similar to using EL34s - it would just need swapping the cathode resistors. You would get a top class EL34 amp for under £1000 with great iron and standard valves. Looks good too.
 
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pmcuk

Wammer
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Sep 12, 2015
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Another look on eBay reveals that this amp can and has been modified as above. This mod uses 6550 tubes in the output and a new mains transformer, which is larger than the original. Very tasty but the original mains transformer looks better. Input tubes are EF86 and ECC85 or 6N1P. These are actually written on the top plate so may be a variation. All very intriguing. There are 24 of these amps on eBay because of the output tube rarity, mostly in Japan and most over £1,000.

https://www.ebay.co.uk/itm/115981686756

Luxman MQ-60 6550d.jpeg Luxman MQ-60 6550g.jpeg
 

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