LJM Audio

ljm_ljm · 2012-03-09 4:14 am

back said:
hi can it take 75volt?

i already have a toroid i would like to use.

No problem.It can use the +-75V

sdman · 2012-03-09 1:45 pm

I still don't see a schematic.
Why don't you admit you don't have it or won't supply it
Quit jacking with us.
If you are going to sell amp kits, do it right.

ljm_ljm · 2012-03-09 3:49 pm

Circuit often changes the changes.Can not be used as the correct design.
May refer to #5.
In the KIT, not with the document.

ljm_ljm · 2012-03-09 4:11 pm

alkasar said:
Happy new (chinese) Year ljm

Laugh.
Is done and leave for some time. The work is very busy, as well as there is no time to DIY and to forums.

Was too busy

sdman · 2012-03-09 7:46 pm

Let's see the correct design and do away with all the excuses.

Man!, you are dancing all around the right answer and solution.

solviken · 2012-03-09 8:49 pm

So is there anyway to BRIDGE two of these modules? and what would the power rating be?

solviken · 2012-03-09 9:59 pm

Just forget the last post.. postet it in the wrong forum, was supposed to be in the L25D

trunkline · 2012-03-17 2:49 am

I have a chassis with preamp and a PSU of +-DC 53V . I have only to decide for the power amplifier and protection circuitry.

What provides better sound, an Class A / B amplifier as the L7 or a classe D as the L15D?
If you prefer the class D, which is the difference between modules and the module L15DX2 L15D (other than being double)? Why the larger size of the L15DX2 caps ? Which is better?

Idefixes · 2012-03-18 9:25 pm

hi ljm,

Could you give the heatsink thermal resistance carateristics that you involve in L15D ver.3?

Marc

soren5 · 2012-03-19 10:18 pm

L15D for active 2-way?

I’ve been lurking this and the L20D thread for some time and have a few questions about the boards. I’m building an active 2-way bookshelf speaker with a full range driver and a bass woofer where I plan to use the 2 x L15D boards + 1 x SMPS inside each speaker. The full range driver is 8 ohm 20W and the is woofer 4 ohm 150/300W (nominal/peak). For power supply I’m planning to use the SMPS300RE +-45V.

Will the speaker drivers’ impedance difference be a problem for the L15D boards + SMPS300RE?
Although the SMPS300RE is not taking advantage of the L15D’s full potential (as opposed to e.g. the SMPS500R), will this SMPS be sufficient considering the speaker drivers I’m using?
Is the heat generated from the boards so high that I need to vent the speaker enclosure or even place external heat sinks?

Thanks for the advice.

ljm_ljm · 2012-03-22 5:15 pm

trunkline said:
I have a chassis with preamp and a PSU of +-DC 53V . I have only to decide for the power amplifier and protection circuitry.

What provides better sound, an Class A / B amplifier as the L7 or a classe D as the L15D?
If you prefer the class D, which is the difference between modules and the module L15DX2 L15D (other than being double)? Why the larger size of the L15DX2 caps ? Which is better?

L15DX2 higher than the L15D performance difference is not particularly large.

Distortion smaller.

Analog amplifier L7, its wide range of applications. No fixed rules on the voltage.

Are free to use, L7, very durable

ljm_ljm · 2012-03-27 12:49 pm

soren5 said:
I’ve been lurking this and the L20D thread for some time and have a few questions about the boards. I’m building an active 2-way bookshelf speaker with a full range driver and a bass woofer where I plan to use the 2 x L15D boards + 1 x SMPS inside each speaker. The full range driver is 8 ohm 20W and the is woofer 4 ohm 150/300W (nominal/peak). For power supply I’m planning to use the SMPS300RE +-45V.

Will the speaker drivers’ impedance difference be a problem for the L15D boards + SMPS300RE?

Although the SMPS300RE is not taking advantage of the L15D’s full potential (as opposed to e.g. the SMPS500R), will this SMPS be sufficient considering the speaker drivers I’m using?

Is the heat generated from the boards so high that I need to vent the speaker enclosure or even place external heat sinks?

Thanks for the advice.

It should use the L15D + - 45V DC power supply.

The L15D the fever is lower than the L20D 25D. He can be full of power without the need to increase the radiator.

ljm_ljm · 2012-03-27 12:53 pm

solviken said:
So is there anyway to BRIDGE two of these modules? and what would the power rating be?

Recommended to use this.

Its circuit by IRAUDAMP7S.

It can achieve 500W power 8 OHM

ljm_ljm · 2012-04-01 4:09 pm

noah katz said:
ljm_ljm,

With the heat sink vertical on the board it doesn't look like convective airflow over the fins will be very good, since the board underneath blocks it.

Do you know what is the maximum average power that a module can dissipate when in a closed box?

And how much if the box has ventilation holes above the heat sink?

Also , what are the dimensions of the board? I searched but didn't find them, and the ebay vendors don't give them either.

Thanks

Marked on the front of the reference map detailed size chart I can find.

L15D fever is relatively small in actual use, almost no temperature.

trunkline · 2012-04-18 11:15 am

According to the datasheet of the original IRAUDAMP7s has multiple protection features that have not been included in LJM designs.

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Over-current protection (OCP),

high side and low side MOSFET

Over-voltage protection (OVP),

Under-voltage protection (UVP),

high side and low side MOSFET

DC-protection (DCP),

Over-temperature protection (OTP)

Anyone know if its necessary in original (or ebay copy ) IRAUDAMP7s amp add another protection circuit as a delay for anti-plop or similar?

alkasar · 2012-04-18 11:24 am

trunkline said:
According to the datasheet of the original IRAUDAMP7s has multiple protection features that have not been included in LJM designs.

Anyone know if its necessary in original (or ebay copy ) IRAUDAMP7s amp add another protection circuit as a delay for anti-plop or similar?

Cristi's latest IRS2092 designs are supposed to include multiple protections.
Connexelectronic CxD400
Connexelectronic CxD300

The detailed description is not yet on the website.
Speaker protection board, including anti-pop delay are easy to find on ebay.

ljm_ljm · 2012-04-19 5:39 pm

In fact I have a design similar products.

But after testing his performance is not the L15D good, so I gave up.

I repeated the same reference design based on the IRAUDAMP7S.

But every time the failure of the test in all SMT less than the performance of L15D.

400K HZ PWM frequency. Inductors, capacitors, filters.

Waveform distortion. L15D DIP parts. Distortion is very small.

At present, I still have no way to using SMT instead of DIP.L15D version.

ljm_ljm · 2012-04-19 5:41 pm

SMT test the performance of the oscilloscope performance.

Not a substitute for L15D, maybe I can be solved in the future so that it can be smaller.

ljm_ljm · 2012-04-19 5:44 pm

We need to understand is that the MOSFET temperature is not low.

As the voltage increases. Fever is obvious, because it has a quiescent current.

Therefore, the larger the heat sink must be equipped with.

ljm_ljm · 2012-04-19 5:57 pm

SMT version of the oscilloscope, the picture.

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