I bought a couple of kits, reverse engineered the PCB and have created schematic. Should I publish here?
I'd be interested. Yes, please. 🙂
Can anyone tell me what is the sound quality of the L15D?
Normally the class D sound worse treble.
What would you advise me?, Build a class AB amplifier with mosfet or buy ljm L15D Class D.
to amplify studio monitors.
Thank you.
I'm using L15DX2 as my home amplifier.
Use the computer as a source of sound, PMC FB1 + as speakers.
Its performance is very good.
If you like class AB. A simple small amplifier L6 is very good,
Perhaps you might check out the recent upgrade offered for the PB1+ (now called the PB1i with it's new 'tweeter') - really nice speakers - very good to hear that the L15D suits them so well.
L-15D mounting 4019H & D669 on heatsink
Hi Everyone,
Nearly finished soldering the L-15D modules, but I'm a bit confused about how to mount the 4019H and D669 to the heatsink. The confusion started when looking at pictures of the L-15D Pro on ebay, where it was clearly stated that insulation should be used. Is this needed for the L-15D as well? Or can they be just mounted to the heatsink directly?
Hi Everyone,
Nearly finished soldering the L-15D modules, but I'm a bit confused about how to mount the 4019H and D669 to the heatsink. The confusion started when looking at pictures of the L-15D Pro on ebay, where it was clearly stated that insulation should be used. Is this needed for the L-15D as well? Or can they be just mounted to the heatsink directly?
Can anyone help me answering my previous question. I know it must be a stupid newby question, but I cannot figure it out. I've looked at the IRF documentation on the 4019H and at the reference design document for IRAUDAMP7D, but could not find any information regarding the insulation. I'm an audio hobbyist looking for help.
Thanks in advance.
Arnoud
Thanks in advance.
Arnoud
Can anyone help me answering my previous question. I know it must be a stupid newby question, but I cannot figure it out. I've looked at the IRF documentation on the 4019H and at the reference design document for IRAUDAMP7D, but could not find any information regarding the insulation. I'm an audio hobbyist looking for help.
Thanks in advance.
Arnoud
I purchased a pair of completed L15D's and they did not have insulating pads on the devices, so you are probably fine without. Notoriously, they also did not have any heat sink compound, which I made sure to add before firing them up.
Depends on the package. Does your 4019H have a metal back ? if yes, an insulation is needed.Can anyone help me answering my previous question. I know it must be a stupid newby question, but I cannot figure it out. I've looked at the IRF documentation on the 4019H and at the reference design document for IRAUDAMP7D, but could not find any information regarding the insulation. I'm an audio hobbyist looking for help.
Thanks in advance.
Arnoud
Seems to me that IRFI4019H is in an insulated package, so no need for insulation pad.

However, I would definitively put thermal paste !
edit: oops, response crossed MrSlim 😉
Hi MrSlim & Alkasar,
Thank for your replies. I will mount them with some thermal paste to the heatsink. 🙂
Thank for your replies. I will mount them with some thermal paste to the heatsink. 🙂
L7 Amp
I too have bought the kit and have reversed engineered the schematic. I'd like to compare mine with others. What is the verdict on sharing?
I'm using the L7 to replace a blown power amp in a Janis Interphase 1A subwoofer amp. I'm almost ready to power up. I'd like to cross check my schematic before doing so. I plan to power up slowly using a variac, but am not sure what to look for on the output mosfet voltages. i.e. if they were bipolars, I know I can watch for the Vbe's to come up to 0.7. Any tips?
I too have bought the kit and have reversed engineered the schematic. I'd like to compare mine with others. What is the verdict on sharing?
I'm using the L7 to replace a blown power amp in a Janis Interphase 1A subwoofer amp. I'm almost ready to power up. I'd like to cross check my schematic before doing so. I plan to power up slowly using a variac, but am not sure what to look for on the output mosfet voltages. i.e. if they were bipolars, I know I can watch for the Vbe's to come up to 0.7. Any tips?
How this L15D performs on low power levels 5-10W ?
I'm not sure how much power i'm using whilst listening to my music, but I doubt I ever reach 5 - 10 Watt RMS 🙂
It sounds pretty good on my Dynaudio Audience72SE. When compared to a lyngdorf TDAI 2200 it lacks a little refinement (harsher highs), but for the money i think it is unbelievable. There is a little white noise when you put your ear close to the tweeter. According to the specs it should be dead silent. The amps are connected to a connexelectronic SMPS 800RE powersupply and they get their signal from a Emotiva XDA-1 DAC. This is all rather subjective. Will post more factual information later.
Hi, right now I'm testing L15D amp, I have to say, it sounds very good at low volume levels, I am satisfied 🙂
Anyway the output inductor is quite hot, is it normal ? My idle current consumption are -50mA and +30mA (+/-55V). I have L15D kit (and all components) from eBay zoe_tsang shop. Inductor is square type OFC? 14A / 0.012Ohm. Thanks.
Anyway the output inductor is quite hot, is it normal ? My idle current consumption are -50mA and +30mA (+/-55V). I have L15D kit (and all components) from eBay zoe_tsang shop. Inductor is square type OFC? 14A / 0.012Ohm. Thanks.
Please share complete L7 schem and pcb
Nice small Amp, sch. & pcb 2.
Regards zeoN_Rider
Inductor is will have some fever. Especially in under the condition of no sound output.
PWM 400 k close to power supply voltage (+ - 50 V) signal continued through the inductor, reduce to 0.5 V.
But we can ignore it.
PWM 400 k close to power supply voltage (+ - 50 V) signal continued through the inductor, reduce to 0.5 V.
But we can ignore it.
Hello, I bought to Along1986 the kit L15D ver3 last year (two boards) and I have the same problem with the two boards: the positive supply voltage rises gradually from +52 to +72 volts vots and negative supply down from - 52 volts to -38 volts, thereby raising the temperature of the resistance of 3K3 which feeds the zener 5V6 on positive supply.
I built the two boards and I guess I made a mistake when placing components, LJM, can you send me the schematic and component mask? can it happen by self oscillation?
Test condition:
Power supply: +/-52 volts, linear
Input: no signal, open.
Output: 10 ohms load and without load.
Blue Led: ON
Signal at output: ~400Khz, 400 mV p-p
Sorry for my bad English.
Regards,
Daniel.
I built the two boards and I guess I made a mistake when placing components, LJM, can you send me the schematic and component mask? can it happen by self oscillation?
Test condition:
Power supply: +/-52 volts, linear
Input: no signal, open.
Output: 10 ohms load and without load.
Blue Led: ON
Signal at output: ~400Khz, 400 mV p-p
Sorry for my bad English.
Regards,
Daniel.
Last edited:
Hello, I bought the kit to Along1986 L15D ver3 last year (two boards) and I have the same problem with the two boards: the positive supply voltage rises gradually from +52 to +72 volts vots and negative supply down from - 52 volts to -38 volts, thereby raising the temperature of the resistance of 3K3 which feeds the zener 5V6 on positive supply.
Daniel.
This sounds like bus pumping. It is most prone when applying a sine wave especially low frequency.
When inputting normal music it should be fine.
the positive supply voltage rises gradually from +52 to +72 volts vots and negative supply down from - 52 volts to -38 volts,
Daniel.
Looks like a PSU problem to me , no signal no buspumping .
check your transformer centertap to ground connection .
Cheers ,
Rens
- Home
- Vendor's Bazaar
- LJM Audio