I recently received a pair of L20D amplifiers (assembled) from ebay. On the back of the board it says 'please add the tin thickness' with arrows pointing to exposed tracks. Am I supposed to tin these with solder? I was looking at LJM's photos at the start of this thread and he does not appear to have tinned his.
You can ignore it.
This is can use tin, increase the PCB conductive performance. Reduce resistance.
The bare position can be through the larger current.
You can ignore, use directly.
Attachments
I have recently purchased L25D modules on eBay. This weekend I was using them and approx. 20 minutes after using there was a cracking sound and the module shut down. One speaker element (expensive and out of production
) was damaged - the voice coil was burnt right off.The module was quite hot when this happened and I could feel the difference in heat compared to the intact module. It was not possible to power up the damaged module, but as far as I can see there is no damage to the PCB or burnt components on the board.
The ebay seller told me about the potential batch problem of 4020.
Very unfortunate and I am angry at my self for not testing the modules for longer with some cheap speakers... or using a speaker protection PCB.
Because it is not a common value, like 0.775V, 0.9V or 2.0V.
But actually it is not a big problem, I must set the output level of my DAC with appropriate resistor divider. The only thing is that I shoud know the real value.
I will make some test measurement to determine that....
As I understand it, the L series amps are based on the IR designs but unlike the IR reference designs, the LJMLJM versions are actively supported by LJMLJM himself.
L20D quality
Hi All
I've just completed an L20D build bought from Along on Ebay. It sounds OK, but definitely doesn't seem to live up to the high standards I've ben reading about in this thread. I feel I'm going wrong somewhere - perhaps power supply.
I'm using a 300VA 50V dual output toroid using a chipamp power supply board. I'm using MUR860 diodes and 2 x 10,000uF 100V Caps (one per rail). Compared to my reference amp (Rega Mira 60W integrated) it sounds a bit choked or lacklustre. This is my first listen to Class D amps so I'm not really sure what to expect......but I guess I was expecting a lot of headroom and a bit more 'hi fidelity'. Any suggestions very welcome!
Hi All
I've just completed an L20D build bought from Along on Ebay. It sounds OK, but definitely doesn't seem to live up to the high standards I've ben reading about in this thread. I feel I'm going wrong somewhere - perhaps power supply.
I'm using a 300VA 50V dual output toroid using a chipamp power supply board. I'm using MUR860 diodes and 2 x 10,000uF 100V Caps (one per rail). Compared to my reference amp (Rega Mira 60W integrated) it sounds a bit choked or lacklustre. This is my first listen to Class D amps so I'm not really sure what to expect......but I guess I was expecting a lot of headroom and a bit more 'hi fidelity'. Any suggestions very welcome!
I've used +/-72Vdc with both lps and smps on L20D and L25D and they sound excellent with my Swan F2.2 speakers. Perhaps it's your lower supply voltages, I haven't tried 50Vdc rails so can't confirm if there'll be a performance drop. It seems more appropriate for L15D.
Then again, the modules have very low input Z, ca 3kR. Make sure your source is a good match for that.
Then again, the modules have very low input Z, ca 3kR. Make sure your source is a good match for that.
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I have the PGA2311 inside the amp - so it's essentially an integrated amp. I guess this means it's not the pre. Perhaps I am just used to class AB amps......I'm just finding that it is lacking in top end sparkle. Would you describe it as being a touch on the dark side?
Would changing the caps mentioned early in this thread help? Or any other mods?
Cheers
Would changing the caps mentioned early in this thread help? Or any other mods?
Cheers
I had a look at the PGA2311 spec sheet and it does have an inbuilt opamp stage that claims to drive 600R loads without buffering. Perhaps it's the implementation/sound of this preamp that's underwhelming? You might want to give it time to run in though.
No the L20D does not sound dark. It does have an input decoupling cap that's not of the best quality and this does make the sound 'warmer'. If your source outputs a DC-less signal, you could short the cap. I did that and there's a noticeable improvement in detail and sparkle. Just remember your amp is now DC coupled and test all sources for DC Offset before connecting. Otherwise, change to a better, bipolar cap. I've used K73-16 russian ex military caps, they're cheap and actually pretty good.
No the L20D does not sound dark. It does have an input decoupling cap that's not of the best quality and this does make the sound 'warmer'. If your source outputs a DC-less signal, you could short the cap. I did that and there's a noticeable improvement in detail and sparkle. Just remember your amp is now DC coupled and test all sources for DC Offset before connecting. Otherwise, change to a better, bipolar cap. I've used K73-16 russian ex military caps, they're cheap and actually pretty good.
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I swapped out the 33uF little cans for some cheap 22uF NP caps and there is definitely a touch more presence. Sounds pretty darn good actually. I wonder if it's worth swapping out the other little electros?
if it lacks anything it's musicality.....and that's not something that is easy to measure. I'll give it a listen for a few weeks and I might change my mind though.... thanks for the help.
if it lacks anything it's musicality.....and that's not something that is easy to measure. I'll give it a listen for a few weeks and I might change my mind though.... thanks for the help.