Luxman SQ38FD

[Ninox 8]

I have been gifted a Luxman sq38fd. From original owner bought in the 1970s. 
It has some problems and I wanted to know if people think it’s worth going down the rabbit hole of repairs. 
1. strong burning smell when turned on and one 50CA10 valve glows like the fires of hell. 
2. volume switch crackling

3. Stereo / mono switch just cuts out sound occasionally. 
4. it has new preamp valves - woohoo!

 

so I am asking cause I don’t know the endpoint an amp like this gets to. I want to use it with my Klipsch Forte III speakers. If it’s a magical sound and the right repairs give years of happy listening I will go ahead but I am unlikely to want to spend heaps on average. For example a set of 4 50CA10 tubes can be $900 on the net. That might be US$.

Thanks

[VanArn 611]

The safest course is to have the Luxman converted to use EL34 output valves.  This will involve the fitting of a filament transformer and other modifications. This should be less costly than trying to use  NOS valves or replicas from Chinese sources.  

[Ninox 8]

14 minutes ago, VanArn said:

The safest course is to have the Luxman converted to use EL34 output valves.  This will involve the fitting of a filament transformer and other modifications. This should be less costly than trying to use  NOS valves or replicas from Chinese sources.  

Thanks very much. Do you know anyone who does this around Sydney?

[VanArn 611]

Possibly Rage Audio  in Sydney could be contacted, otherwise you may have to send your amplifier to Melbourne.

[Ninox 8]

Thanks - the original owner says he might have a box of 50CA10 tubes somewhere so I see if that turns up and if not - off to Rage (should they be interested!)

[muon* 2,711]

Likely needs a going over, and if all original some caps would likely need replacing and controls and connectors cleaned.

 

Nice amp and worth restoring IMO, some nice iron in these old Luxman amps.

 

That conversion Van suggests would future proof things as far as valve replacement availability goes.

Edited December 6, 2020 by muon*

[xlr8or 620]

10 minutes ago, muon* said:

Nice amp and worth restoring IMO.

 

Fully agree. This amp is definitely worth restoring. Just did some tinkering to my Luxkit A3600 power amp yesterday and can now use KT120's for the 8045G, which like the 50CA10 is unobtainable. My mod involved adding an 8.2 kohm 3 watter to the bias circuit before the 30 kohm pots, which each split into 10 kohm pots for the push pull pair. Not digressing, 50CA10's do come up on Yahoo Aleado from time to time and at a good price. Use Jauce as your proxy and you're in business.

 

I would retain all original aspects of the circuit including the use of the 50CA10 tube as on-sale value would be significantly higher. Try reaching out to Chris at Kimal Electronics for restoring it back to its original condition. Can help with circuit diagram if needed.

[muon* 2,711]

Good point on originality and value

[Ninox 8]

Thanks everyone - the original owner has found three more 50CA10 which is optimistic. I’ll let you know how I go. 

[Ninox 8]

The amp was serviced by Chris at Kimil and now sounds amazing. Incredible beautiful midrange. All knobs and buttons working and absolutely silent. Through the Klipsch ForteIII its a very appealing presentation.