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Deleted member 148505
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Deleted member 148505
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Deleted member 148505
Unmodded SKA GB150D with dual source resistors and speaker protection.
Size: 3" x 4.9"
I noticed on the SKA web site they mention that the amp can be "converted" to deliver up to 50W into 8R under class-A operation. Can you board also be configured that way?
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Deleted member 148505
I noticed on the SKA web site they mention that the amp can be "converted" to deliver up to 50W into 8R under class-A operation. Can you board also be configured that way?
CMIIW only resistor values are needed to be changed in order to operate it in high bias push-pull class-A mode. 50W into 8R requires 3.4A quiescent current, large heatsinking is needed and power supply should be very good, to be able to run it in class-a mode.
I'm using the "public" released schematic, but with individual source resistors for each mosfet. I also included the following features on the PCB:
- Speaker Protection Circuit/Power on speaker delay.
- MKT or Back to Back Electrolytic for Input Cap.
- Input Capacitor can be bypassed by a jumper (like jumpers in computer motherboard/hdd).
- Uses E-B-C small signal transistors. (2n5401/5551)
- Thermal sensing transistors on top of Output Mosfets.
Regards,
Lester
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Hi JLester,
It was good to meet you and bought 2 of your amps, though I have not installed it yet, I will surely let you know results after.
best regards
Erick
Yes, thanks for dropping by Don't hesitate to contact me if you need help.
Hi JLester. I'm hoping you can advise,
I have 2 of your Audiophile-250 boards, sharing an enclosure with 2 LJM L25D boards. Each amp channel has a separate, linear power supply, only connecting on the mains side.
I've had no issue sharing both JLAudio boards 12VAC off of a single transformer so I assumed that I could also use that transformer for another speaker protection board that I'm using with the L25D's which also takes 12VAC, however when I do I get an (extremely loud) 60Hz buzz through all amplifier channels. (ground loop?)... When I lift the earth connection, temporarily, nothing changes.
My temporary solution was to add another 12vac transformer to power the external speaker protection board. The buzz is gone, but I'd really like to simplify the layout as much as possible.
Can a single 12VAC supply with sufficient current not power the external SPboards as well as the JLA's?
Thanks
Sent from my Nexus 7 using Tapatalk
I have 2 of your Audiophile-250 boards, sharing an enclosure with 2 LJM L25D boards. Each amp channel has a separate, linear power supply, only connecting on the mains side.
I've had no issue sharing both JLAudio boards 12VAC off of a single transformer so I assumed that I could also use that transformer for another speaker protection board that I'm using with the L25D's which also takes 12VAC, however when I do I get an (extremely loud) 60Hz buzz through all amplifier channels. (ground loop?)... When I lift the earth connection, temporarily, nothing changes.
My temporary solution was to add another 12vac transformer to power the external speaker protection board. The buzz is gone, but I'd really like to simplify the layout as much as possible.
Can a single 12VAC supply with sufficient current not power the external SPboards as well as the JLA's?
Thanks
Sent from my Nexus 7 using Tapatalk
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Deleted member 148505
I laughed as I took this picture because visually its a mess.
You're correct. I didn't have the grounds tied together. I've just tied the ground planes together from the 3 sets of capacitor banks and I believe it has made the system a bit quieter on a whole, it didn't solve the buzz. With the additional transformer I only hear a clean hiss. When I combine the 12v I get the same loud buzz.
I doubt that this image will help. I'll try to draw a simplified schematic this afternoon.
Thanks
You're correct. I didn't have the grounds tied together. I've just tied the ground planes together from the 3 sets of capacitor banks and I believe it has made the system a bit quieter on a whole, it didn't solve the buzz. With the additional transformer I only hear a clean hiss. When I combine the 12v I get the same loud buzz.
I doubt that this image will help. I'll try to draw a simplified schematic this afternoon.
An externally hosted image should be here but it was not working when we last tested it.
Thanks
Not related but I've just discovered that I've created a nice short in the way I mounted my torroids.
I'm changing the entire layout so please disregard this issue.
Thanks,
Justin
That's right, you made a shorted turn. There should not be an electrical conductive path that passes through the center of the toroid and around the outside.
Mount the two transformers on top of each other with a single bolt down through the chassis bottom. This was done for instance on the Aragon 4004 MKII amplifier:
Thanks Charlie.
I've just done the same, but with a wooden base. This is all going into a sub once it's done.
I've just done the same, but with a wooden base. This is all going into a sub once it's done.
An externally hosted image should be here but it was not working when we last tested it.
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Would love your opinion on the sound quality of the SKA bords vs the the audiophile 250D boards!
Haven't heard the GB150D yet. JLAudiophile-250D is very good sounding specially when paired with a good preamp.
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A client requested me to replace the busted amp section of Krell kav-400xi.
The result: zero noise and very good sounding amp
The result: zero noise and very good sounding amp
Attachments
Hi guys,
Did anyone compare JLAmp1000D with L25D from LJM ?
Also I found this one (quite cheap with protection and capacitors included):
Yuan Jing Audio - IRS2092 Class-D Mono Amplifier Board [350W+350W] + Speaker Protection - $48.10 - Class-D & T
Anyone experienced with this one?
Did anyone compare JLAmp1000D with L25D from LJM ?
Also I found this one (quite cheap with protection and capacitors included):
Yuan Jing Audio - IRS2092 Class-D Mono Amplifier Board [350W+350W] + Speaker Protection - $48.10 - Class-D & T
Anyone experienced with this one?
Upcoming products:
Auto power on based on music signal detection.
My Ref Rev C
IRAUDAMP9 based mono class-d amplifier.
Nice. Any idea when the power-on PCB will be available?
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Deleted member 148505
Nice. Any idea when the power-on PCB will be available?
2 to 3 weeks from now
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