Hi,
just sent for a chinese JLH 10 watt amplifier kit.
I intend to see what it sounds like using better parts than come with the kit.
The power transistors are 2n3005. I think these can take quite a large voltage.
My question is can the wattage be increased and how would I do it.
Is it just more DC voltage in and higher rated caps etc.
cheers and Happy New Year.
just sent for a chinese JLH 10 watt amplifier kit.
I intend to see what it sounds like using better parts than come with the kit.
The power transistors are 2n3005. I think these can take quite a large voltage.
My question is can the wattage be increased and how would I do it.
Is it just more DC voltage in and higher rated caps etc.
cheers and Happy New Year.
No.
Read up on some basics about electronics. Check out Rod Elliot's ESP site which has some good articles from basics about amplifiers and electronics.
For now, just build the amp as it's meant to be. Putting faster transistors in might introduce instability. When you understand a bit more then you can play about with it. Nothing worse than trying to get a kit working when you don't know.
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hi ritchie, your post came through to my email unedited.
I do have a clue about what I'm doing, repaired Exposure amps repaired Linn amps, built other JLH designs Chiarra pre amp power supplies etc. Built a pair of Isobariks from scratch!!!! Been swapping systems for 40 years.
Had a couple of magic smoke incidents but haven't we all.
As I asked, just unclear regarding the theory of output wattages.
I will read.
cheers
I do have a clue about what I'm doing, repaired Exposure amps repaired Linn amps, built other JLH designs Chiarra pre amp power supplies etc. Built a pair of Isobariks from scratch!!!! Been swapping systems for 40 years.
Had a couple of magic smoke incidents but haven't we all.
As I asked, just unclear regarding the theory of output wattages.
I will read.
cheers
Hi
there is a table featured in an update to the original design that seems to suggest that the output wattage is dependant upon the input voltage of the transformer. As the input voltage rises the output wattage rises.
The Class-A Amplifier Site - JLH Class-A Update
a secondary voltage of 30v will give 60 watts into 8 ohms.
Could I stand corrected or is that my original thought from my post.
there is a table featured in an update to the original design that seems to suggest that the output wattage is dependant upon the input voltage of the transformer. As the input voltage rises the output wattage rises.
The Class-A Amplifier Site - JLH Class-A Update
a secondary voltage of 30v will give 60 watts into 8 ohms.
Could I stand corrected or is that my original thought from my post.
Input voltage to the transformer - I think you mean transformer secondary voltage (input voltage to the amplifier).
The table does show that 30V gives 60W into 8R, but you can't do this with the standard circuit. Notice the high power circuit has a different design (uses constant current sources) and with two pairs of output transistors still is only safe for 40W. Also the split power supply means there are two secondaries (each 30V using your example). You would need another pair of output transistors, and possibly some increase to the current in the voltage amplifier stage, again which takes some knowledge of the implications and may result in instability.
The table does show that 30V gives 60W into 8R, but you can't do this with the standard circuit. Notice the high power circuit has a different design (uses constant current sources) and with two pairs of output transistors still is only safe for 40W. Also the split power supply means there are two secondaries (each 30V using your example). You would need another pair of output transistors, and possibly some increase to the current in the voltage amplifier stage, again which takes some knowledge of the implications and may result in instability.
hi ritchie, I meant the input voltage to the board from transformer,secondary.
1969 version, if I'm limited with this design I'll try to get as many watts as poss. I think the limit may be 15 watts.
I'm actually pretty impressed with it. Hard to believe so few components can give such good sound. I built mine to test out using a server power supply for audio. I haven't installed it in a case yet because I want to try some different power supplies with it first. The server power supply is way over kill at 47A but it puts out 26VDC which the amp seems happy with. I used MJ15003 outputs. Mine was not a kit. It was built using the Jim's Audio boards.
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