LJM Audio

[doctordata]

L15D ?
I know that some Connexelectronic amplifiers do have an addtional opamp at the input.

L15D is single ended , I was referring to the CxD2160 from Connex .

Cheers ,

Rens

 

[dublin78]

Hi

I am thinking of using three pairs of these boards for a minidsp based active system:

Woofer: 8ohm 88dB
Midrange: 4ohm 90dB
Tweeter: 4ohm 94dB

I would like to power them with Connex SMPS800 at +-50vdc

Any problems with this?

 

[arlis]

I think that should work fine.

 

[elb]

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

Hi Rens,
could you please explain why you would reverse phase 4 ohm speakers when supplying the L15D with 55v,

Thank you in advance.

 

[doctordata]

Hi Rens,
could you please explain why you would reverse phase 4 ohm speakers when supplying the L15D with 55v,

Thank you in advance.

In order to avoid bus pumping with the high currents with 4 ohm speakers it is advisable to run one of the stereo channels with a phase inverter ( and reverse the polarity of the speaker on that channel ) .

Cheers ,

Rens

 

[elb]

In order to avoid bus pumping with the high currents with 4 ohm speakers it is advisable to run one of the stereo channels with a phase inverter ( and reverse the polarity of the speaker on that channel ) .

Cheers ,

Rens

Thank you for the explanation,much appreciated.

 

[umut1001]

There are 2 types of l15dx2 class d amps.One of them is green and other is blue.Is there any quality difference of them ?Maybe pcb quality ?

 

[chanaka1989]

I'm planning to use a L15D module for my subwoofer. Is there any modification which can be made to use it as a sub woofer amplifier? Or is it better with the default configuration? Please help

 

[doctordata]

I'm planning to use a L15D module for my subwoofer. Is there any modification which can be made to use it as a sub woofer amplifier? Or is it better with the default configuration? Please help

Just make sure you have plenty of rail buffering ( at least 10.000 uF per rail ) and use short and heavy gauge wiring for power and speaker wiring and the standard L15D should work fine .

Cheers ,

Rens

 

[chanaka1989]

Just make sure you have plenty of rail buffering ( at least 10.000 uF per rail ) and use short and heavy gauge wiring for power and speaker wiring and the standard L15D should work fine .

Cheers ,

Rens

Thanks
One more question about cables. I have used the following type of cable for interconnections.



Is it sufficient?

 

[Max Woof]

Hi,
I am thinking to use 2 toroidal transformers, 34 volt 400VA each to drive 4 ohm speakers. From what I understand this should give me 48 volt rails, suggested for 4 ohm speakers. What do you think- is it a little too much or what ?

 

[ljm_ljm]

LJM New Small toys GC LM3886

Small toys

Take a look at first.

Pictures than text easier to understand.

 

[ljm_ljm]

3886 PDF The standard circuit.

No input capacitance. Use direct input.


ljm_ljm@foxmail.com

 

[Philfr]

Hi,
What difference with your LM3875 ?
I build :

An externally hosted image should be here but it was not working when we last tested it.

Please note that it's works with 28 volts, cause relay are 24 vdc.
It does the job for the cheaper price !
Why softstart with LM3886 ?
Phil.

 

[AndrewT]

.....................Why softstart with LM3886 ?.............

Has the advertisement mentioned soft start for the LM3886?

Soft start is usually for the transformer.

Speaker isolation and delay is different.

 

[Mooly]

Moved to Vendors forum. Please restrict all future similar posts to this one thread.

(ljm_ljm, this thread, like many of your others, seems more commercially orientated ... lack of build details, sharing of circuit information and so on)

 

[ljm_ljm]

Hi,
What difference with your LM3875 ?
I build :

An externally hosted image should be here but it was not working when we last tested it.

Please note that it's works with 28 volts, cause relay are 24 vdc.
It does the job for the cheaper price !
Why softstart with LM3886 ?
Phil.

LM3886 LM3875 they are fine.

Relay is through the half-wave rectifier, plus LM7824 for use in relay power supply.

So no problem.

LM3875 now, here I seldom buy chips.

LM3886 more. As for the voice. I think they are close to.

Maybe LM3886 speed faster.

 

[ljm_ljm]

Moved to Vendors forum. Please restrict all future similar posts to this one thread.

(ljm_ljm, this thread, like many of your others, seems more commercially orientated ... lack of build details, sharing of circuit information and so on)

In my introduction illustrates it USES LM3886 PDF circuit in detail.

It is very simple. I want to discuss this circuit. Rather than sell it at the BBS.

I don't have international account. If someone buy it from China. I would be happy to explain some problems for others.

As long as someone ask. All can get the exact answer.


Thank you very much for your help I placed it in the right place.

Because I really don't know where it should be given.



Can refer to the official information about circuit. The following diagram is introduced.

I appropriately increased input LPF, as well as Zobel network.

 

[Philfr]

Hi,
Few questions from newbie :
1 can remove Rb 1 Ko (input resistor) ?
2 gain is 21 ?
3 is that "speaker protection" works when a DC signal is at input ?
4 where buy it to China from Europe ?
5 relay is 24 vdc ?
Thank's.
Phil.

 

[ljm_ljm]

Hi,
Few questions from newbie :
1 can remove Rb 1 Ko (input resistor) ?
2 gain is 21 ?
3 is that "speaker protection" works when a DC signal is at input ?
4 where buy it to China from Europe ?
5 relay is 24 vdc ?
Thank's.
Phil.

1 don't delete R1, in fact, behind the product R1 and a capacitance. 15 pf.
It with R1 LPF filter.
2 gain = 21 voltage amplification.
3 have a dc voltage output. Will cut off the output.
4, can use the TAOBAO net. I can only use it. Can I email to ljm_ljm@foxmail.com
5. Relay use 24 v dc voltage. But it passes through a LM7824 voltage regulator IC. The half-wave rectifier.
Suggested that the transformer use AC24-0 to 24