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new layout for LFA 50A

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J

JEP

Member
Joined 2005
#1
A few years ago I fully redid the layoutdesign for my elektuur lfa50a.
the componentplacement is about the same but there is more room voor biggercaps and foil c's. I also made a large board for the big powercaps. As you can see on the attachment. So there are almost no wires anymore. I think that looks very cool. And the best thing is its sounds really great too.

I have an 2sk389 as inputdifamp because 2sk146v was not avaliable anymore. And no inputcap. Because my preamp has outputcaps. But I can always put room for one on the layout if you want one.

Let me know, Roy

To me the lfa50a is a great amplifier
 

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#2
roy algra said:
A few years ago I fully redid the layoutdesign for my elektuur lfa50a.
the componentplacement is about the same but there is more room voor biggercaps and foil c's. I also made a large board for the big powercaps. As you can see on the attachment. So there are almost no wires anymore. I think that looks very cool. And the best thing is its sounds really great too.

I have an 2sk389 as inputdifamp because 2sk146v was not avaliable anymore. And no inputcap. Because my preamp has outputcaps. But I can always put room for one on the layout if you want one.

Let me know, Roy

To me the lfa50a is a great amplifier
Click to expand...

Looks great! I have the LFA50-OA as well, but in the original configuration. Great sounding amp!

Scanspeakman
 
#3
Hi scanspeakerman,

I have it for 15 years now but never had a thoughd about replacing it. A friend of mine Who has worked for an highendstore who has had a lot of amplifiers in his system had them on loan for a while said that overal the lfa50a was the best amp for his system.

Its a real great amp.

Thanks roy
 
#4
Hi Roy,

I am using the amp for about the same period I guess. Seems indestructable. Only other amp I am considering is the Elektor Extrama but I am not able to find any topics on the net displaying the results of some who has build the Extrema.

I am planning to give the LFA50-OA an overhaul in the next few months (slitfoils for the big powercaps, some panasonic fc's in other positions etc). I'll probably post some pictures when I am done.

What kind of pre-amp are you using with the LFA50-OA?

Scanspeakman
 
#8
The parts are not that hard to find, there's still someone active overhere who offers a replacement for some of the CRD's you need.

Major issue with the design is the heatsinking for power levels above 50W, my strong advice is to use fan operated high performance heatsinks.
A big help is the availability of Kerafol insulating foil, 7.5'' x 7.5'' sheets can be ordered from Conrad. (one of EUVL's great pointers)
I originally used thin aluminum oxyde TO247 insulators, adapted to size to fit under the big Sanken cases.
The Kerafol sheets are easy to slice into MT200 case sizes with an office paper cutter, saves quite a few temperature points compared to Mica, any other insulator sheet make is not to my liking.

Second item would be what preamp to use with this power amp.
Logically speaking, the preamp deal would also have to be a balanced package, very low on distortion, high on dissipated watts.

You wouldn't be the first overhere to build it, but the first to comment on it.
 
#14
Hi Guys,

I also have the LFA-50 for many years now😉, but mine started to act strange.
Build it in 1996. One of my channels is not working properly anymore.
When i cranck up the volume of the pre amp, it wil boost in suddenly, when i put the volume down again it will stop working again. Sometimes it will stay working all the time.
When i want to listen to music, i first have to play very loud to get both channels working😕. And then see what it does when i put the volume down again.
Many times i am listening in mono now, because i can't get one channel working properly
Very irritating😡, what do you think is the cause of this. Are my output Transistors dying?
Has any of you guys the same problem.
In the meantime i already started building the Extrema Amp. But would like to fix this lovely amp till the Extrema proofs to be a better amp😀.
 
#17
Hello,

I saw that You projected a new layout pcb for LFA -50 A class amplifier. I know that it was a few years ago but I wondering about build this unit.
Is this possible that you could schare a file PCB for this unit?
Could you compare LFA - 50 to something?
On first i was thinking to build LFA - 150 but in past i build a few typicall A/B class amplifier and i wondering about A class construction.
I have experience in building and repair amplifiers.
 
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