@MattHauck : I assume you meant Q3. Please confirm the values of the resistor values for R4 and R15 and measure the DC voltage drops across them as well.
And please post photos as Jim suggested.
And please post photos as Jim suggested.
Please Check without power with a ohm Meter if there are Connection e.g. GND or Power on all Points Where They should. And Check if there are Shorts where They dont allowed to be. -E.g. Plug, connector etc.
Power on and Check all DC values Are correct.
then send Signal and Check with Oszi
@6L6 Pics attached, thanks all!
@Dennis Hui I did indeed mean q3, not q4. Reading 10.6 V across r4 (10.7 on the left side for reference). Reading 4.4 V across r15 on both sides.
@DIYHarry I have checked the connections that are obvious to me, but, I am a neophyte here, so I'm sure I'm missing ones that could explain what is going on.
As I was taking the pics, I noticed that the joints on q3 were a little messy, so I cleaned those up already. I tested afterwards, and the situation has only gotten stranger.
When I take the input directly from the headphone port on my MacBook Air, both channels work, with the right a little quieter. But, when I use my DAC (Khadas Tone 1, connects and powered via USB from my MacBook), there is NO sound on the right channel. When I switch sides on cables to make sure it is not the input from either the laptop or the DAC, I get the same: Line in from laptop- quieter on right channel of ACP+ and input from DAC, no sound at all from the right channel.
Is something creating resistance in the right channel that the headphone out is able to overcome with higher voltage compared to the line-level out of the DAC?
I only get more confused!
@Dennis Hui I did indeed mean q3, not q4. Reading 10.6 V across r4 (10.7 on the left side for reference). Reading 4.4 V across r15 on both sides.
@DIYHarry I have checked the connections that are obvious to me, but, I am a neophyte here, so I'm sure I'm missing ones that could explain what is going on.
As I was taking the pics, I noticed that the joints on q3 were a little messy, so I cleaned those up already. I tested afterwards, and the situation has only gotten stranger.
When I take the input directly from the headphone port on my MacBook Air, both channels work, with the right a little quieter. But, when I use my DAC (Khadas Tone 1, connects and powered via USB from my MacBook), there is NO sound on the right channel. When I switch sides on cables to make sure it is not the input from either the laptop or the DAC, I get the same: Line in from laptop- quieter on right channel of ACP+ and input from DAC, no sound at all from the right channel.
Is something creating resistance in the right channel that the headphone out is able to overcome with higher voltage compared to the line-level out of the DAC?
I only get more confused!
And for sake of avoiding future problems, please clean leftover flux off the board with a toothbrush and 90% or higher isopropyl alcohol. Perhaps I'm a neat nick, but it certainly can't hurt. If a joint wobbles, while scrubbing, that's a sure sign that desoldering is needed at that joint (ask me how I know).
You can get a million opinions about what's best for soldering thru hole PCBs. Try some of them out. I started this hobby fairly recently. Read lots of how to solder articles but doing it again and again was the best teacher. It just takes practice. I am now getting good results with a 2mm chisel tip on a Hakko FX888D (see Amazon) using Diyaudiostore Firemetal solder. There are other good Eutectic solders. At the moment my iron is set at 360° which seems to be working for me. You have to find the right temperature for each job and tip. All of this is a preamble to saying I concur with @Halauhala. In fact I'd reflow almost all your joints, especially if they don't look like the one above. I'm still a noob but I think you need either a higher temperature, a little more time, or both on most of your joints.
Thanks for the tips y’all. This was my first build like a year ago and for subsequent projects (Lxmini crossover, ACA) I’ve been getting better results with higher temp and firemetal. Was hoping to avoid reflowing everything, but it makes sense.
If that does not solve the issues of intermittent sound on the right channel, I’ll report back. Just seems so strange that it is source dependent! Appreciate the help everyone!
If that does not solve the issues of intermittent sound on the right channel, I’ll report back. Just seems so strange that it is source dependent! Appreciate the help everyone!
OK. Reflowed everything, and replaced input and output wiring to RCA jacks on the chassis for good measure. Frustratingly, I realized I had never tested it form input 2. So after cleaning everything up, I tested input 2...and it all works fine.
BUT input 1's right channel is still is either dead silent or playing quieter than the left channel depending on the source. The Kardas Tone1 DAC board, mounted same chassis (but with short RCA jumpers from output to input), is silent on the right channel; and when I run RCA straight from my MacBook Air, it plays on both channels, but slightly quieter on the right. Also, when plugged into RCA from my laptop, I can hear it faintly on the other input as well as the input its plugged in to. Not the case with the orca's from the DAC board.
Also tested line out to my ACA. All the same issues, PLUS static that does not correspond with my volume knob. No static through headphones though. And only static when plugged into some source.
Could these all be symptoms of a grounding issue?
Sorry if this is all newbie stuff. This was my first time trying to mount a board in a chassis, and I think I may have bit off more than I can chew at this point in my learning.
BUT input 1's right channel is still is either dead silent or playing quieter than the left channel depending on the source. The Kardas Tone1 DAC board, mounted same chassis (but with short RCA jumpers from output to input), is silent on the right channel; and when I run RCA straight from my MacBook Air, it plays on both channels, but slightly quieter on the right. Also, when plugged into RCA from my laptop, I can hear it faintly on the other input as well as the input its plugged in to. Not the case with the orca's from the DAC board.
Also tested line out to my ACA. All the same issues, PLUS static that does not correspond with my volume knob. No static through headphones though. And only static when plugged into some source.
Could these all be symptoms of a grounding issue?
Sorry if this is all newbie stuff. This was my first time trying to mount a board in a chassis, and I think I may have bit off more than I can chew at this point in my learning.
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Thanks @DIYHarry ! There is a low level buzz or hum, unaffected by the volume knob, when the ACP+ is connected to an amp and speakers AND one of the inputs is connected to a source. No buzz through headphones or when no source is connected.
My power jack is not insulated like that, so that seems like a place to start!
My power jack is not insulated like that, so that seems like a place to start!
This is a fantastic website, forum, and community! This is my first post, but I hope my questions aren’t too clueless.
I am planning to build an ACP+ and ACAmini combo, starting with the ACP+. I noticed Nelson wrote, “We were quite surprised to discover that the ACP+ played loud enough for ordinary listening.” - So it’s possible the ACP+ alone will work for my space.
1. Both kits come with the 24V power supply. Is it possible to power both units with one power supply? Or do both units need to be run off the 2 separate supplies? What is the combined wattage requirement for the 2 units together?
2. Is it possible to buy the parts kits without the power supply? I don’t really want to have yet another unused wall wart kicking around.
3. The build guide for the ACP+ states, “Note: If you plan on building this without a chassis you must use the ground plane.” Is the ground plane in this case just a physical guard, or does it have a function in the circuit? If the “chassis” is a wood base, is the ground plane needed?
4. The ACA Mini doesn’t seem to have a ground plane board. Why not?
5. When connecting a turntable with a ground wire as an input, does that get connected to the standoff/ground plane lug?
Thank you!
I am planning to build an ACP+ and ACAmini combo, starting with the ACP+. I noticed Nelson wrote, “We were quite surprised to discover that the ACP+ played loud enough for ordinary listening.” - So it’s possible the ACP+ alone will work for my space.
1. Both kits come with the 24V power supply. Is it possible to power both units with one power supply? Or do both units need to be run off the 2 separate supplies? What is the combined wattage requirement for the 2 units together?
2. Is it possible to buy the parts kits without the power supply? I don’t really want to have yet another unused wall wart kicking around.
3. The build guide for the ACP+ states, “Note: If you plan on building this without a chassis you must use the ground plane.” Is the ground plane in this case just a physical guard, or does it have a function in the circuit? If the “chassis” is a wood base, is the ground plane needed?
4. The ACA Mini doesn’t seem to have a ground plane board. Why not?
5. When connecting a turntable with a ground wire as an input, does that get connected to the standoff/ground plane lug?
Thank you!
Hello and welcome! Very glad to see you here.
The speakers that Nelson was using when that comment was made were very efficient. Around 93db, which is uncommon. Normal speakers, unless listening perhaps in something like a desktop computer situation where you don't listen very loud, will be insufficiently powered by just the ACP+.
1) Sure, you could run them off the ACAmini PSU. I wouldn't, but you could. EDIT: Are you wanting to build in one chassis? Then yes, just use the ACAmini PSU.
2) No.
3) It's for electrical shielding. A metal chassis would not need the ground plane. Wood, however, would.
4) The signals involved are a whole lot bigger.
5) Does this turntable have a phonostage built in? Regardless, yes, the ground wire should be attached to ground of the ACP+.
The speakers that Nelson was using when that comment was made were very efficient. Around 93db, which is uncommon. Normal speakers, unless listening perhaps in something like a desktop computer situation where you don't listen very loud, will be insufficiently powered by just the ACP+.
1) Sure, you could run them off the ACAmini PSU. I wouldn't, but you could. EDIT: Are you wanting to build in one chassis? Then yes, just use the ACAmini PSU.
2) No.
3) It's for electrical shielding. A metal chassis would not need the ground plane. Wood, however, would.
4) The signals involved are a whole lot bigger.
5) Does this turntable have a phonostage built in? Regardless, yes, the ground wire should be attached to ground of the ACP+.
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Thank you, 6L6 - and thanks for the clarification!
My intention is to stack the ACA-mini above the ACP+ in a common chassis, as I have seen on a few examples here, so I will use the one PSU. One I saw (a clone) also had a ground plane board between the 2 units, which I assume is to shield the ACP+ from above as well as below. The chassis will be a wood base with an aluminum front panel. The "cover" will be a metal screen, but it should be essentially open for circulation.
I will post a model for critique soon.
My intention is to stack the ACA-mini above the ACP+ in a common chassis, as I have seen on a few examples here, so I will use the one PSU. One I saw (a clone) also had a ground plane board between the 2 units, which I assume is to shield the ACP+ from above as well as below. The chassis will be a wood base with an aluminum front panel. The "cover" will be a metal screen, but it should be essentially open for circulation.
I will post a model for critique soon.
It is playing music...sounds very nice on the headphones
A bit a mess
What I do not understand is that it, to become stable, have to warm up 10 minutes before the servo can do it's job. The offset between the + and - terminals of the balanced amp is very stable, even during those 10 minutes it stays lower than 5 millivolts of drift.
But beteen the + and - terminal and ground, it starts at 3.5 volt getting lower when warming up, and then is locked by the servo.
The behaviour is that during warming up the positive side of the amps is pulling much more current than the negative side. It seems like the constant current source with the 4N35 is not so constant...it pulls around 240mA, getting lower to in the end around 160mA, when everything is in balance and stable.
Anybody knows why is this behaviour?
I did not notice it when I build my single ended ACP.
Maybe the great ZM can chime in?
I also want the servo to make more impact, do I lower the 150K output resistor on the opamp?
Will try that.
I saw in ZM's Babelfish XJ schematics, he is using 1K5, 100 times lower.
The servo is connected to the sources of the two JFET's in the LTP.
This is the schematic:
A bit a mess
What I do not understand is that it, to become stable, have to warm up 10 minutes before the servo can do it's job. The offset between the + and - terminals of the balanced amp is very stable, even during those 10 minutes it stays lower than 5 millivolts of drift.
But beteen the + and - terminal and ground, it starts at 3.5 volt getting lower when warming up, and then is locked by the servo.
The behaviour is that during warming up the positive side of the amps is pulling much more current than the negative side. It seems like the constant current source with the 4N35 is not so constant...it pulls around 240mA, getting lower to in the end around 160mA, when everything is in balance and stable.
Anybody knows why is this behaviour?
I did not notice it when I build my single ended ACP.
Maybe the great ZM can chime in?
I also want the servo to make more impact, do I lower the 150K output resistor on the opamp?
Will try that.
I saw in ZM's Babelfish XJ schematics, he is using 1K5, 100 times lower.
The servo is connected to the sources of the two JFET's in the LTP.
This is the schematic:
output resistor of servo OPamp needs to be dimensioned that OP never get to glue output to rail
situation that servo isn't able to do its role from cold is showing that you didn't met all conditions, simply said servo is not having range big enough to control what's needed
where is complete schematic, so I can see how it is connected with rest of circuit?
disclaimer, ZM being Omni, thus hardly expert in anything specific, especially servos
situation that servo isn't able to do its role from cold is showing that you didn't met all conditions, simply said servo is not having range big enough to control what's needed
where is complete schematic, so I can see how it is connected with rest of circuit?
disclaimer, ZM being Omni, thus hardly expert in anything specific, especially servos
Hi ZM, nice talking to you again.
I edited my schematic so I can show you how it is connected now.
See picture.
The opamp is connected to + and - out with 1M resistors, and the 150K opamp output resistor goes to the 3 sources of the JFET's.
I saw in yor Babelfish you had also 2 x 100K to the outputs connecting to that point.
(Note that the outputs have 33 Ohms load resistors, original I had for R70, R71, R102, R103 100 Ohm resistors, but they are now a wire bridge.)
I also tried instead of the potmeters and 680 Ohms, a straight 1K resistor ( as in papa's schematic) but then I had 35mV offset between the +out and -out terminals of the balaced amp... and I could ofcourse not rotate my potmeters to get it to zero, my favorite
Big question is, why is it single ended so stable at 160mA and the 4N35 is doing it's proper job. But not if you build it like this, balanced???
I edited my schematic so I can show you how it is connected now.
See picture.
The opamp is connected to + and - out with 1M resistors, and the 150K opamp output resistor goes to the 3 sources of the JFET's.
I saw in yor Babelfish you had also 2 x 100K to the outputs connecting to that point.
(Note that the outputs have 33 Ohms load resistors, original I had for R70, R71, R102, R103 100 Ohm resistors, but they are now a wire bridge.)
I also tried instead of the potmeters and 680 Ohms, a straight 1K resistor ( as in papa's schematic) but then I had 35mV offset between the +out and -out terminals of the balaced amp... and I could ofcourse not rotate my potmeters to get it to zero, my favorite
Big question is, why is it single ended so stable at 160mA and the 4N35 is doing it's proper job. But not if you build it like this, balanced???