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LJM Audio

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#341
chanaka1989 said:
Hello nigelwright7557!

Thank you very much for your help. It seems like almost all the zener diodes have become faulty. I think it happened because I interchanged the vcc and vee 🙁

I can find IN4148 zener diodes easily so is it possible to replace 5v6 and 15v zener diodes with IN4148s? Also do you have any idea about the other faulty items which caused by the interchange of vcc and vee. I'm going to change both mosfets and irs2092.

Update:
I got the speaker protection part working (atleast the relay works) but the blue led doesn't come on. Connected a speaker and I can barely hear continuous pops from the speaker.
(Replaced a 5v6 zener diode with IN4148 and a 15v zener diode with a IN4148 zener diode)
Click to expand...
I can't judge what is specific parts damaged.
And L15D - PRO transistor is not universal.
Can't replace.
 
#343
I bought L-15D-pro kit from zoe_tsang on ebay. It was very nicely packed. But when I started to assemble the kit I noticed that for all capacitors that are labeled on board as 22uF I got 220uF. I believe it's a mistake at packing the kits, or should I put in those 220uF capacitors?
 
#345
I contacted Zoe and it was said to me that she spoke to people that prepare the kits and explained to me, that I should use 220uF indeed. The sound should be better she said. Than I made also contact to ljm_ljm and he said that I could use 220uF and the voltage of them should be 16v or above. He didn't say anything about sound quality. I had at home some non polarised 22uF capacitors and put those in. I don't dare to put 220uF in.

I also run the module at +-40V instead of +-50V. Should I change any other components at this running voltage?
 
#346
Update a few pictures about the appearance of connection diagram.
 

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#348
speaker protection

chanaka1989 said:
Thanks for your support. I ordered a L15D kit (without speaker protection)
Do I need to use a separate speaker protection circuit or it isn't required for L15D?
Click to expand...

Hi Chanaka ,

Your L15D amp should work fine without protection , but to protect your speaker(s) against any failure of the amp it is advisable to add an external DC speaker protection circuit .

Cheers ,

Rens
 
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#349
Voltage

ID_ said:
I contacted Zoe and it was said to me that she spoke to people that prepare the kits and explained to me, that I should use 220uF indeed. The sound should be better she said. Than I made also contact to ljm_ljm and he said that I could use 220uF and the voltage of them should be 16v or above. He didn't say anything about sound quality. I had at home some non polarised 22uF capacitors and put those in. I don't dare to put 220uF in.

I also run the module at +-40V instead of +-50V. Should I change any other components at this running voltage?
Click to expand...

It should run fine on +/- 40V The minimum pull in voltage for the Songle relay is 75% of the 48V , that's 36V . The 220uF caps make not much difference , except for the input cap , it will lower your low frequency cutoff , a 22 uf non polarized should be fine there , but the 220 uF would do no harm either , maybe a bit of a "thumb" at start up , depending on your source .

Cheers ,

Rens
 
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#350
Hi

I've decided to build L15D power amplifier (not the pro version) using a smps psu.
Thinking of SMPS300RE as the psu is it enough for powering 2 boards ?
What voltage input should i choose 45v or 55v (audio quality is top priority).

Thanks !
David
 
#351
motorica said:
Hi

I've decided to build L15D power amplifier (not the pro version) using a smps psu.
Thinking of SMPS300RE as the psu is it enough for powering 2 boards ?
What voltage input should i choose 45v or 55v (audio quality is top priority).

Thanks !
David
Click to expand...

Hi David ,

Depends on your speaker impedance . In my experience and reading all the international forums , the L15D seems to sound slightly better in the higher voltage region . Your mentioning 55V , if you use 4 ohm speakers I would go for a 500 or 600w power supply and run them in reverse phase .

Cheers ,

Rens
 
#353
motorica said:
Thanks for the reply Rens

My speakers (monitors) are rated 6 ohm, any reason why i should operate them in reverse phase ?

Hard to decide between l15d and IRS2092 Modular Amplifier from connexelectronic
Connexelectronic

Thanks !
David
Click to expand...

Reverse phase is to avoid bus pumping as the L15D has a very limited protection set , but sounds real good .
Have a look at this combination , fully protected including DC fast off and power supply and good specs and price .
Connexelectronic

Cheers ,

Rens
 
#357
Let me +1 Connexelectronic amplifiers.
Connex amplifiers will sound the same as the other irs2092 as they all share the same schematic and key components. Connex benefits are larger caps, better pcb layout, output filter inductor really able to sustain the rated power, less noise, smaller form factor.


doctordata said:
Reverse phase is to avoid bus pumping
Click to expand...
How do you do that ? I can only think of reversing the phase of 1 channel which requires an additional circuit.
 
#358
drahcir said:
I recommend that you guys use an external speaker protect for this board,dont rely on the internal protection,trust me it cost me a pair of vifa tweeters :banghead::banghead::banghead:

Sent from my Desire HD using Tapatalk 2
Click to expand...

This board uses a DC sense circuit that switches the power supply off instantly when any DC is detected on the output , which is sufficient when you use the amp in full range mode ( different story when you use the amp in an active setup as mid or high amp )

Cheers ,

Rens
 
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