Author Topic: Luxman CL32 recap  (Read 483 times)

Offline fdlsys

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Luxman CL32 recap
« on: January 02, 2022, 06:30:55 PM »
This was a small safety & sanity restoration project.

When I bought the preamp it had one of the 4-cap bank replaced in the most unusual way. Probably using the first cap in the drawer matching the spec. Except for being axial, not radial, so implementation was... hmmm... potentially lethal.

I always open the vintage equipment before I power it up, just in case. In this case, it was a life saver. Since I didn't have a matching radial 33uf/350v handy, I inserted a piece of foam under the bent uninsulated leg hoovering over the 3 unrelated solder points on the PCB by a few microns.



I used it like this for quite a while and then used something else, and something else, until I found the time to replace all caps in that bank. Simple rule of thumb - if one in the bank was bad, the others must be marginal at best.

This is what I saw after I took them out. All 3 original radials leaked electrolyte.



So, 4 modern high temp low ESR EL caps and two best Wima MKP4 (why not...) later, safety and sanity were restored.





After:



At this point, I must mention Luxman's design ingenuity, being able to fit a 7 valve preamp with an amazing set of built in features into a box that is about 1/4 of the volume of equivalent ARC and half the volume of Conrad-Johnson preamps from the same era. Neither of which had half of the inputs, adjustments and switchgear functions that this little marvel has.

At the same time, working on it is as easy as top off, bottom off, everything accessible.
Quality of switchgear is beyond reproach. Rotary switches are open so they can be spray cleaned or the wafers taken out and serviced or replaced.

A few photos to demonstrate just how marvelous this little thing is.













Late great Tim de Paravicini told me that he can't remember being involved in the CL32 design; there was another engineer, Japanese, that was working on preamps during Tim's stint at Luxman when he designed the famous MQ3600 and a few other power amps based on the same valves and topology.

But the amount of pure genius that can be found in details of this preamo just screams Tim dP to me.
« Last Edit: January 02, 2022, 06:39:41 PM by fdlsys »
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Offline fdlsys

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Re: Luxman CL32 recap
« Reply #1 on: January 02, 2022, 06:48:15 PM »
And here it is, paired with MQ3600, a cult Tim dP power amp design, originally built for bespoke NEC TV valves but designed in such a way that it could be easily converted to use KT88.
In the meantime, the KT120 became mainstream, so that's what I decided on.
With greatest respect and all thanks to our own valve guru and unsung (enough) hero Alan Hobkirk who did the actual conversion because I was sweating crocodiles at a thought of me poking into a 400v+ circuit.













PS: benefit of using KT120 - at 2/3rd od their max bias they push the same power as the original valves so even with all the heat they generate, they will likely last many 1000s of hours.
« Last Edit: January 02, 2022, 06:51:38 PM by fdlsys »
The four building blocks of the universe are fire, water, gravel and vinyl. Dave Barry
Come back when you’ve lived a little. Miles Davis

Offline fredeb

Re: Luxman CL32 recap
« Reply #2 on: January 02, 2022, 11:24:32 PM »
Absolutely beautiful equipment and restoration work Mike ! Nice !


...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
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Online FranZAR

Re: Luxman CL32 recap
« Reply #3 on: January 03, 2022, 07:24:28 AM »
Excellent work Mike. Glad they ended up with you.

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Offline HH NS1000

Re: Luxman CL32 recap
« Reply #4 on: January 04, 2022, 05:50:03 AM »
Stunning Mike.  :2thumbs:
If you don't understand your own perceptions you cannot really make any sensible judgements.....or should I say you would not really fathom the conclusions you come to.

Online El Sid

Re: Luxman CL32 recap
« Reply #5 on: January 05, 2022, 11:00:05 AM »
And here it is, paired with MQ3600, a cult Tim dP power amp design, originally built for bespoke NEC TV valves but designed in such a way that it could be easily converted to use KT88.
In the meantime, the KT120 became mainstream, so that's what I decided on.
With greatest respect and all thanks to our own valve guru and unsung (enough) hero Alan Hobkirk who did the actual conversion because I was sweating crocodiles at a thought of me poking into a 400v+ circuit.




PS: benefit of using KT120 - at 2/3rd od their max bias they push the same power as the original valves so even with all the heat they generate, they will likely last many 1000s of hours.

Beautiful! I may just have to nick them next time I visit....

Offline humfr33

Re: Luxman CL32 recap
« Reply #6 on: January 10, 2022, 11:43:11 AM »
Well done on the restoration of a stunning piece :) I am going to be starting my first restoration project soon - I am going to take my time and make sure I don't bite off more than I can chew.