FS Marantz power amp (Sanken LAPT 2SA1303/2SC3284)
Oct 13, 2009 at 1:31 PM Thread Starter Post #1 of 19


Headphoneus Supremus
Jun 30, 2006
Marantz SM500U Power amp, Sanken LAPT 2SA1303/2SC3284. I am the second owner of this amp and purchased it for use in a system that never materialized so it has sat in the box for the last several months. I did hook the amp up in my living room and it is a very nice amp, just not as synergistic with my speakers as my receiver so I chose not to keep it there. Asking Sold shipped.

Excerpt from original FS thread:

So, there's a bit of a story behind this amp. I purchased it around 5-6 years ago and was a result of a lot of looking around for a commerical amp that used the Sanken LAPT (large area parallel transistor) ring-emitter bipolar output devices (yum!). Part numbers are Sanken 2SA1303/2SC3284.

This amp was designed in Japan, unlike a lot of Marantz gear at the time. This was their first attempt move away from their then cash cow of home theater and back into 2-channel audio... well, that didn't really work, but hey this was one of the nice designs that out of this. In fact, you'll notice that a lot of the board isn't populated, that's because they shoe-horned this design into another board, from what I can tell. The transformer alone is extremely impressive and very heavy. Likewise, the heat sink is overkill and could allow one to increase the bias quite easily. The output devices are known for their midrange and highs, and this is what impressed me about this amp. Large 10,000uF Elna Audio caps are used and are visible in the pictures below.

I've used this with a Stax transformer box and I've driven both Vandersteen and Magnepans with this, despite the impedance rating. I'm not sure I'd recommend it, but hey. I think the best use is with a Stax transformer box and in this role it sounds very nice. I'm hoping someone buys it for this reason alone Extra points if you mod it and just locate the transformer inside the case!

Condition is fair, there are 2-3 deep scratches on the top of the faceplate and the back of the case, but the front is clean. I'm not going to scrutinize it much further, I'd rate it a 6/10 probably.

I have a Marantz double box, but it's unclear whether this box was for this particular amp, but it fits quite nicely.

I'm looking for $200 and you pay *actual* shipping and *actual* PayPal fees. I'd guess the weight to be 40 lbs or so.

A few last things. The model number is SM500U, but there is very little about this amp available that I could find. It was tough to find 5 years ago and that still seems to be the case. I remember paying $500-$750 for it back then (the range because I cannot remember if I got a tuner in it as a package deal or not).

Mar 25, 2010 at 6:26 PM Post #12 of 19


100+ Head-Fier
Oct 15, 2008
You mention you used it on your magnapans but would not reccomend becasue of impendedence issue.
I have a pair of magnapan IIa and am looking for an inexpensive amp to drive them. I saw your ad and then got concerned about using it.
What was meant bu the statement about using the amp for magnapans?

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