I would not put so many filter capacitors on an amp board. Filter capacitors shunt ripple current to the local ground, which tends to create hums.
Note that there are 2 grounds in your schematic. I suggest you bridge 2 grounds with 10 Ohm resistor on your board. The amp needs signal ground to set up NFB ratio. It won't work if the signal ground is floating in air without signal source connected.
I installed 4A fuses after the secondary windings of the transformer. The amplifier has been working for more than 4 years.
Does someone has an extra set of PCB for sale or the black and white layout for home-brew type PCB?PCB rev 1.2 for A23
@olafk very good layout , nice compact design .....
I think just a few members like my PCB rev 1.1 so I decided to try all in line OT for A23 so here it is .....but not tested !
Regards Alex
I am interested on both option, would love to build this amp the A23.
Greetings gabor
Can I ask what is your heatsink size and rail voltage?
I'm using 2U 300mm sinks and plan to experiment with variable voltage before I make final purchase of transformers.
I will try 45V rails and 4 ohm load and check dissipation to see if its rising to high. Might have to use under 45V
Hello everyone,
I am an inexperienced college student wanting to build the AX11 as my final project for my audio engineering class. However, I am struggling to find all the AX11 version to choose from. I want to choose a version of the AX11 that do not use non-obsolete component like the BD249C, so I can buy easily. That is why I hope people can help me categorized and recommend me a simple AX11 model that I can simulate and build. I only need schematic and not the pcb because I do not have the skill and access to make pcb.
I am sorry if I do not know a better way to find the schematics and posts. All I had done for the past couple days are searching for key words for the post and through apexaudio facebook. If there is a better way to search, I hope you can direct me to a way to find all the model of the AX11.
Here are all AX11 model I have so far:
AX11
AX11F
AX11H-KLASA
AX11NS
AX11S
AX11TEF
AX11CS
the elusive AX11-MK2? that use MJL3281A, MJE340, BD139
and another version like the AX11-TEF using the 2S5200 and MJE340.
If you are so grateful to recommend me a power supply that I can use for AX11 as well, I will very appreciate that. I do not have knowledge on that, and many of the symbol on the schematic doesnt make sense to me (PGND, PRO, squigglely diode, a square with diagonal cross, a switch with dotted line). I am thinking of just using 2 (20V, 3.25A) laptop power supply in series to get +-20V, but not sure if that would work wire in series or the ax11 would work. I have a Technics SB-X1 that is 6 ohms, weird, and 50W peak. Even if I build the Ax11, I still overpowered that speaker. Is there a way to lower the power?
Thank you so much for your help.
I am an inexperienced college student wanting to build the AX11 as my final project for my audio engineering class. However, I am struggling to find all the AX11 version to choose from. I want to choose a version of the AX11 that do not use non-obsolete component like the BD249C, so I can buy easily. That is why I hope people can help me categorized and recommend me a simple AX11 model that I can simulate and build. I only need schematic and not the pcb because I do not have the skill and access to make pcb.
I am sorry if I do not know a better way to find the schematics and posts. All I had done for the past couple days are searching for key words for the post and through apexaudio facebook. If there is a better way to search, I hope you can direct me to a way to find all the model of the AX11.
Here are all AX11 model I have so far:
AX11
AX11F
AX11H-KLASA
AX11NS
AX11S
AX11TEF
AX11CS
the elusive AX11-MK2? that use MJL3281A, MJE340, BD139
and another version like the AX11-TEF using the 2S5200 and MJE340.
If you are so grateful to recommend me a power supply that I can use for AX11 as well, I will very appreciate that. I do not have knowledge on that, and many of the symbol on the schematic doesnt make sense to me (PGND, PRO, squigglely diode, a square with diagonal cross, a switch with dotted line). I am thinking of just using 2 (20V, 3.25A) laptop power supply in series to get +-20V, but not sure if that would work wire in series or the ax11 would work. I have a Technics SB-X1 that is 6 ohms, weird, and 50W peak. Even if I build the Ax11, I still overpowered that speaker. Is there a way to lower the power?
Thank you so much for your help.
Attachments
I have checked those schematics like 5-times and I only see PRO, which could be PROTECT, i.e. input to separated protect board. Please draw or tell me where the others symbols are.
I'm building a quad amp with NX12's. Started up the first board. Sound is good with excellent bass control and dead silent with no signal
When I measured the square wave it produces a ramp past 5khz with the slope angle increasing up to 20khz but no overshoot.
Hmm, probably nothing audible with extended listening in stereo, maybe, maybe not🤔
When I measured the square wave it produces a ramp past 5khz with the slope angle increasing up to 20khz but no overshoot.
Hmm, probably nothing audible with extended listening in stereo, maybe, maybe not🤔
Attachments
Greetings to all.
I'm facing with a strange problem with my AX14 amplifier with 2 op. One channel is ok, have tested the sound also. But the other channels dc offset is unstable, it's bouncing from 20 to 120 mv and above within seconds and it keeps on. I have checked every component thoroughly, desoldered it and again assembled it twice, but the issue is same. All BC547, 2N5401 are matched. Bias set to 50mA (16.5mV).+/-56;V rail voltage.
Connected a speaker, it's producing hissing noise. Kindly help me.
I'm facing with a strange problem with my AX14 amplifier with 2 op. One channel is ok, have tested the sound also. But the other channels dc offset is unstable, it's bouncing from 20 to 120 mv and above within seconds and it keeps on. I have checked every component thoroughly, desoldered it and again assembled it twice, but the issue is same. All BC547, 2N5401 are matched. Bias set to 50mA (16.5mV).+/-56;V rail voltage.
Connected a speaker, it's producing hissing noise. Kindly help me.