Review and Measurements of L20.5 Loudspeaker Amp

[Biblob]

Great, looking forward to it!

 

[maty]

Finally, I want to say... I can't hear the obvious distortion

Maybe you need good/very good recordings. Just now, an exceptional vinyl rip.

Elton John - Goodbye Yellow Brick Road (1973), Vinyl x2, EMI-Odeon / Zafiro, Spain

https://www.diyaudio.com/forums/music/6958-playing-listening-post5821248.html

 

[Chilli]

Nice going. Such a pity, as I was in Shanghai a couple of weeks ago. Really interested to see your measurements on speakers over there. Esp the cheaper ones. Many years ago I bought a pair of hivi speakers. Are you thinking of measuring made up speakers or separate drivers tweeters?
I will look into this amp and the modification shown.

 

[bunkbail]

I'll send amir a pair of L20.5's in a couple of days

Did you followed up on this idea with amirm? I'm interested in this amp myself.

 

[cookiefactory]

Interested as well!

 

[bigjacko]

Any update on this? If you are in China probably easier to send it to wolfx to measure if he is interested in this amp.

 

[Eenaii]

You say not to use switching power supply. Why is that?

 

[AlexScan]

I re-birth the topic... i have two L20.5 in a DIY amp with a very big SMPS (1200w, on Aliexpress) + adding very lot of capacitors (+12000µF per rail)

Anyone make a good measurement of this amp ?

The MODification is effective or not ? ... the conceptor LJM tell on DIYaudio that is just a wire, zero change for him...

With a few hours of test i find the medium very pleasant (a bit much forward maybe) but the bass wass not very tight...

I remove the input cap and I think the sound is worse without it (this is the first time i remove a input cap and loose sound quality...) ... This week is re-put the input cap and make the MOD...

 

[mslim]

Which one is better?

LJM L12-2 vs LJM L20.10 ?

Any measurements?

 

[mslim]

Why is the L20.5 mentioned here when the latest version is L20.10? Any difference?

 

[carlmart]

Anyone can confirm if this is the LJM L20 schematic, in version 5 or 10?

What is exactly the mod that was made to the original modules?

Any asc simulation files to play with?

 

[maty]

https://www.diyaudio.com/forums/vendor-s-bazaar/180625-ljm-audio-post6169008.html

LJM-Audio L20.5 Amplifier by Saarmichel, with measurements.

Optimized pictures. Too big, better as attachs.

 

[mslim]

I saw this and I’m there as well. Does it measure well based on what the builder measured? I only understand a bit and mainly what is measured here by ASR.

Also the use of SMPS here is interesting as the original design calls for the use of linear power with LJM rectifier board and speaker protection board (not sure how that affected the measurements).

This is about half the price of an IcePower class D amp here.

 

[maty]

I saw this and I’m there as well. Does it measure well based on what the builder measured? I only understand a bit and mainly what is measured here by ASR.

Also the use of SMPS here is interesting as the original design calls for the use of linear power with LJM rectifier board and speaker protection board (not sure how that affected the measurements).

This is about half the price of an IcePower class D amp here.

Yes it measures quite well. Of course, I would use yes or yes Cresnet SMPS.

https://www.diyaudio.com/forums/vendor-s-bazaar/281413-audio-smps-units-sale.html

https://www.micro-audio.com/index.php?route=product/category&path=59

 

[AlexScan]

I make the modification see on page one and one my L20.5 burn at startup (maybe the two)... i miss something ?

 

[Nebbermind]

I make the modification see on page one and one my L20.5 burn at startup (maybe the two)... i miss something ?

Do you mean the output transistors fried?
Oh dear! There are 8nos. on each board, right?

 

[DaveFred]

Yes it measures quite well. Of course, I would use yes or yes Cresnet SMPS.

https://www.diyaudio.com/forums/vendor-s-bazaar/281413-audio-smps-units-sale.html

https://www.micro-audio.com/index.php?route=product/category&path=59

Why Cresnet SMPS?

LJM mentions not to use an SMPS with the 20.5. I wonder why that is?

 

[AlexScan]

Do you mean the output transistors fried?
Oh dear! There are 8nos. on each board, right?

I don't know if transitor or other thing fried but one module "make sparks" at power ON.

I let him down, I concentrate myself on building TPA3255 modules with my friend Jlester on DIY audio.