AX11 Building - Dealing with both electronics and autism

Hello Community,

I hope this message finds you all in good health and high spirits. I'm reaching out to this knowledgeable forum with a humble request for assistance that holds significant importance to me.

I recently registered here, driven by my passion for electronics and music, to embark on a project that's close to my heart: crafting my very own audio amplifier. This journey has been incredibly rewarding so far, but I've reached a point where I could use a helping hand from experienced minds who understand the intricate world of electronics design and PCB layout.

I must admit that the learning curve has posed some challenges, and my autistic traits have added a layer of complexity to this process. I have always hesitated to share my personal journey, as I've encountered instances where discussing my condition led to misunderstanding or undesired pity. But today, I've decided to reach out because I believe there might be individuals here who can empathize with my journey.

This journey has brought me to the "Apex AX11", a project that struck a deep chord within me due to its intentional omission of a variable resistor and its unique approach to grounding. However, despite my enthusiasm, I've encountered challenges that have left me feeling somewhat stuck. While it's conceivable that the creator of this schematic may be a member of this forum, I remain uncertain about his current level of activity.

In essence, I'm hoping to connect with someone who understands the complexities of dealing with both electronics and autism. Any support and guidance, no matter how small, would be immeasurably valuable to me.

I've dedicated time to studying schematics and electronics, often navigating the journey alone. The process can be incredibly frustrating, especially when the path forward isn't clear. This is where I now find myself, seeking to navigate the realm of components selection, schematics and PCB layout.

I discovered EasyEDA, a software that breathed new life into my project by offering ready-made component designs. However, my struggle now centers on translating my schematic into a coherent PCB layout. I find that as I move components around, lines appear to shift connections unpredictably. While I understand that components ultimately interconnect, this uncertainty leaves me concerned that I might unintentionally make errors.

In short, I'm reaching out for assistance. Opening up and seeking help is challenging for me, but my intuition tells me that the incredible minds of this forum might hold the solutions I seek. This project means the world to me, and I believe that the understanding and knowledge within this community can help me overcome these obstacles.

To provide some context about the project, I've made a few component substitutions:

BC546 to BC546ABU
MPSA92 to KSP92BU
BD249C to TIP35C
BD250C to TIP36C

MPSA13 - Did not find a candidate

I'm seeking your valuable input on whether these component swaps are suitable for the audio amplifier design. Additionally, do you recommend any adjustments to resistor and capacitor values to ensure compatibility and optimal performance?

I've also noticed a particular detail within the schematic that has prompted a query. In regard to the speaker (-) input, I've observed an arrow denoted as GND. Could you kindly provide clarification regarding whether the speaker (-) input should be linked to this designated GND arrow? Furthermore, I'm inquisitive about whether the ground stemming from the input should be connected to the left-ground point. Alternatively, is the GND originating from the power supply intended to be connected to the GND point on the right side? Additionally, should both the (+) and (-) speaker inputs be connected to the Output?

I extend my deepest gratitude in advance for any insights, guidance, or assistance you might offer. Your willingness to help me on this journey is a gesture that I deeply appreciate.

Thank you for taking the time to read my message. Your kindness and expertise mean more than words can express.

Warm regards,
Prognosis


1692193162452.jpeg
 
There is a lot of information in the Apex threads.
And many builders who have completed working Apex designs.
Many include already designed layouts for etching.
Other users likely have created Gerbers for order.
Which you could use or study.

This particular model not sure.
likely a search could reveal more.

MPSA13 is readily available with supplier Mouser
In circuit used for thermal tracking.
Strange way to do it with a Darlington.
Many would use TO-126 package so it can be mounted
on the heatsink.
and have adjustable bias.
Should be close or on the heatsink regardless
for thermal tracking.

If the thread title included " Help with Apex AX11"
Would likely bring in more participates
and advice/links from actual builders.
Since there is many, but are likely unaware the thread
is discussing the amplifier.
Highly likely there is a layout already done, and could
be used. Or offer insight how to do a layout
 
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Moderator
Joined 2011
Yes, the input ground and the speaker ground go to that same line on the schematic.
The schematic is more of a logical diagram than a literal placement drawing,
but you can try to follow the general layout for placement.

Don't worry about the traces yet. Spend your time getting really good component placement.

Here is a storehouse of information, probably more than you want or need.
https://www.diyaudio.com/community/threads/a-directory-of-apex-audio-amplifiers.292226/
 
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Regarding the other issue, there are more people with autism on this forum. I'm one of them, and I know of several others who are either diagnosed with autism or have the strong suspicion that they are autistic. Whether it will help or hinder you when you make your own equipment depends on what traits you have and how strong they are. The typical autistic attention to details can sometimes be quite benificial.
 
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Aspergers syndrome gives me a long attention span and intense focus on my projects, to the exclusion of social relationships. Some projects take over a year to be successful fully. I view aspergers as a positive for completing complex projects, especially as forums like diyaudio allow me to communicate with my fingers instead of talking to people and looking them in the face. I'm quite odd looking, interracial, (native-am+caucasian) short and generally uaually ignored person to person.
I usually lay the input parts at the opposite end of the board from the output parts. I separate the returns for each with a ohm or half ohm resistor. I don't use layout software since it is incompatible generally with linux op system, and I detest microsoft business practices. I built my apex projects point to point with wire on bare board, nemaCE 1/16" laminate from mcmaster.com. This allows me to fit my project in a case that doesn't fit the standard PCB. I use 24 ga wire for the low power end, and 20 ga wire for the speaker end power supplies & speaker drive. I mount the board to the case with #6 screws through 1/4 air tubing as standoffs. You could bing or google search "Apex AX11 layout image" or pcb image and it might find something.
Be sure to use throwaway speakers for testing an AX11, as solder joints can pop loose and cause DC on the speaker. I prefer the AX6 because it has a single supply, a 3300 uf speaker capacitor, which inherently blocks DC to the speaker for $4. There are pcb boards at the beginning & end of the thread. https://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-42.html Same transistors can be used except the MPSA13 is replace by 2 1n4148 diodes mounted above the output transistors on the heatsink. Actually for heat sense I use 2 1n4148 series a schottky diode for another 0.3 v, then tune down from there with a parallel pot to adjust ouput transistor idle current to 20 ma. Idle current is measured on the .22 or .5 ohm emitter resistors when there is no signal. Same power supply on AX6 as AX11, +-35 are added together on AX6 and the center tap is not used. Dual winding toroids, you connect the 24 ac windings together for AX6 at the middle and use the ends. Transformers are sold under RMS voltage, the voltage shown on schematics on here are peak voltage, 1.4X rms voltage - two diode drops. You want about 450-500 VA transformer for stereo amp with single output transistor pair.
In gereral safety for newbies, don't use two hands on the circuit with the power on. One hand is safe up to 100 v 20 ma source. (not the AC mains input) two hands, 25 ma across your heart can stop it. Wear no rings or jewelry on hands, wrists or neck. 1 v @ 20 a can burn your flesh to charcoal. Wear safety glasses especially soldering desoldering, solder splashes and parts can explode. Use a 100 w incandescent bulb series the AC input to the transformer when testing, up to 2 watts output. Dont work power on distracted by media or people talking to you.
 
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Regarding the other issue, there are more people with autism on this forum. I'm one of them, and I know of several others who are either diagnosed with autism or have the strong suspicion that they are autistic. Whether it will help or hinder you when you make your own equipment depends on what traits you have and how strong they are. The typical autistic attention to details can sometimes be quite benificial.

It's heartening to know that there are others on this forum who can relate to the challenges I face. Understanding things is my main concern, and I can become impatient when explanations are not straightforward. I find that clarity and a logical flow are essential for me to fully grasp concepts. While it might take me some time to find well-explained information, once I do, the complexity becomes manageable.

Let me give you a glimpse into how I approach things – it's a bit of a mixed bag, really. My attention to detail, while admirable at times, can also be a bit of a challenge. Imagine spending hours on a seemingly simple task, like crafting a straightforward letter. That's me, always striving for perfection.

I suppose that's why I was drawn to the design I chose. Its simplicity speaks volumes to me. It's my way of countering the tendency to get lost in the nitty-gritty details.

Sometimes, things might take longer for me, but that's because I'm wired to give my best. Thanks for lending an ear!

Your words are truly appreciated.
 
Yes, the input ground and the speaker ground go to that same line on the schematic.
The schematic is more of a logical diagram than a literal placement drawing,
but you can try to follow the general layout for placement.

Don't worry about the traces yet. Spend your time getting really good component placement.

Here is a storehouse of information, probably more than you want or need.
https://www.diyaudio.com/community/threads/a-directory-of-apex-audio-amplifiers.292226/

Thanks for your guidance. I did check out that thread, but it felt like a bit too much information to digest all at once. I'm thinking of revisiting it when I can give it a proper read.

Clarifying the SE input ground and the speaker (-) is a priority for me.

I appreciate your advice to focus on component placement before worrying about traces.

I've started working on the layout again today, but my patience ran a bit thin. I'll probably finish up tomorrow when I'm feeling refreshed.

Speaking of the layout, are there any potential issues with having both channels on one board?

Lastly, for the potentiometers to function as volume and balance controls, what approach would you recommend?

Many thanks for your support
 
Moderator
Joined 2011
I would suggest that you consider making two identical mono amplifier boards.
Not only will this be easier to design, and be more flexible to implement, but it will work better, too.

The preamp stage is a separate issue, so probably should design one board at a time.
Will you be building all this in one box?
 
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There is a lot of information in the Apex threads.
And many builders who have completed working Apex designs.
Many include already designed layouts for etching.
Other users likely have created Gerbers for order.
Which you could use or study.

This particular model not sure.
likely a search could reveal more.

MPSA13 is readily available with supplier Mouser
In circuit used for thermal tracking.
Strange way to do it with a Darlington.
Many would use TO-126 package so it can be mounted
on the heatsink.
and have adjustable bias.
Should be close or on the heatsink regardless
for thermal tracking.

If the thread title included " Help with Apex AX11"
Would likely bring in more participates
and advice/links from actual builders.
Since there is many, but are likely unaware the thread
is discussing the amplifier.
Highly likely there is a layout already done, and could
be used. Or offer insight how to do a layout

Despite my searches, I haven't come across threads discussing this specific design. However, I'll keep searching for more information.

In regards to the thermal tracking mentioned earlier, could you please help me understand its role? I tend to interpret things quite literally, and I want to make sure I grasp its significance accurately. Your explanation will provide me with a clear path to follow.

In regards to the replacement transistors I mentioned initially, would they be good options? If I were to use them, would resistor and capacitor values need adjusting?

Thank you for your assistance and insights – they're truly invaluable!

Warm regards,
Prognosis
 
Aspergers syndrome gives me a long attention span and intense focus on my projects, to the exclusion of social relationships. Some projects take over a year to be successful fully. I view aspergers as a positive for completing complex projects, especially as forums like diyaudio allow me to communicate with my fingers instead of talking to people and looking them in the face. I'm quite odd looking, interracial, (native-am+caucasian) short and generally uaually ignored person to person.
I usually lay the input parts at the opposite end of the board from the output parts. I separate the returns for each with a ohm or half ohm resistor. I don't use layout software since it is incompatible generally with linux op system, and I detest microsoft business practices. I built my apex projects point to point with wire on bare board, nemaCE 1/16" laminate from mcmaster.com. This allows me to fit my project in a case that doesn't fit the standard PCB. I use 24 ga wire for the low power end, and 20 ga wire for the speaker end power supplies & speaker drive. I mount the board to the case with #6 screws through 1/4 air tubing as standoffs. You could bing or google search "Apex AX11 layout image" or pcb image and it might find something.
Be sure to use throwaway speakers for testing an AX11, as solder joints can pop loose and cause DC on the speaker. I prefer the AX6 because it has a single supply, a 3300 uf speaker capacitor, which inherently blocks DC to the speaker for $4. There are pcb boards at the beginning & end of the thread. https://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-42.html Same transistors can be used except the MPSA13 is replace by 2 1n4148 diodes mounted above the output transistors on the heatsink. Actually for heat sense I use 2 1n4148 series a schottky diode for another 0.3 v, then tune down from there with a parallel pot to adjust ouput transistor idle current to 20 ma. Idle current is measured on the .22 or .5 ohm emitter resistors when there is no signal. Same power supply on AX6 as AX11, +-35 are added together on AX6 and the center tap is not used. Dual winding toroids, you connect the 24 ac windings together for AX6 at the middle and use the ends. Transformers are sold under RMS voltage, the voltage shown on schematics on here are peak voltage, 1.4X rms voltage - two diode drops. You want about 450-500 VA transformer for stereo amp with single output transistor pair.
In gereral safety for newbies, don't use two hands on the circuit with the power on. One hand is safe up to 100 v 20 ma source. (not the AC mains input) two hands, 25 ma across your heart can stop it. Wear no rings or jewelry on hands, wrists or neck. 1 v @ 20 a can burn your flesh to charcoal. Wear safety glasses especially soldering desoldering, solder splashes and parts can explode. Use a 100 w incandescent bulb series the AC input to the transformer when testing, up to 2 watts output. Dont work power on distracted by media or people talking to you.

I'm a bit confused about the 1 or 0.5 Ω concept and how you implement it. Also, when you mention "returns," could you clarify what you mean by that?

On the topic of inputs and outputs, I'm clear; I've been arranging components on the PCB that way.

As for "NEMA CE," I'm not familiar. Does that refer to a type of copper board?

When discussing the AX6, your point about a single supply is a bit complex for me to grasp. I'm guessing you're referring to a 35-0V supply, rather than a 35-0-35V supply. Could you simplify this explanation?

I'm curious about the AX6 design you mentioned; I'll look into it.

Regarding this design, could you tell me its power output at 4Ω ?

Lastly, I'm wondering about the purpose of the 100W light bulb in testing. Could you shed some light on that?

Thank you for your patience in helping me understand these details!

Best regards
 
I would suggest that you consider making two identical mono amplifier boards.
Not only will this be easier to design, and be more flexible to implement, but it will work better, too.

The preamp stage is a separate issue, so probably should design one board at a time.
Will you be building all this in one box?

Would it function more effectively due to concerns about ground loops?

And by "box," are you referring to a case? My intention is to assemble the setup and place it within one of those aluminum amplifier cases. I'm planning on buying some sheets and assembling it myself.
 
Either a stereo amplifier or a stereo preamplifier can have ground loops. All dual mono won't.
But most conventional construction won't have a big problem with noise, if carefully done.

Maybe one stereo preamplifier board, and two mono power amplifier boards, in a single case,
would be a good compromise.
 
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Aspergers syndrome gives me a long attention span and intense focus on my projects, to the exclusion of social relationships. Some projects take over a year to be successful fully. I view aspergers as a positive for completing complex projects, especially as forums like diyaudio allow me to communicate with my fingers instead of talking to people and looking them in the face. I'm quite odd looking, interracial, (native-am+caucasian) short and generally uaually ignored person to person.
I usually lay the input parts at the opposite end of the board from the output parts. I separate the returns for each with a ohm or half ohm resistor. I don't use layout software since it is incompatible generally with linux op system, and I detest microsoft business practices. I built my apex projects point to point with wire on bare board, nemaCE 1/16" laminate from mcmaster.com. This allows me to fit my project in a case that doesn't fit the standard PCB. I use 24 ga wire for the low power end, and 20 ga wire for the speaker end power supplies & speaker drive. I mount the board to the case with #6 screws through 1/4 air tubing as standoffs. You could bing or google search "Apex AX11 layout image" or pcb image and it might find something.
Be sure to use throwaway speakers for testing an AX11, as solder joints can pop loose and cause DC on the speaker. I prefer the AX6 because it has a single supply, a 3300 uf speaker capacitor, which inherently blocks DC to the speaker for $4. There are pcb boards at the beginning & end of the thread. https://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-42.html Same transistors can be used except the MPSA13 is replace by 2 1n4148 diodes mounted above the output transistors on the heatsink. Actually for heat sense I use 2 1n4148 series a schottky diode for another 0.3 v, then tune down from there with a parallel pot to adjust ouput transistor idle current to 20 ma. Idle current is measured on the .22 or .5 ohm emitter resistors when there is no signal. Same power supply on AX6 as AX11, +-35 are added together on AX6 and the center tap is not used. Dual winding toroids, you connect the 24 ac windings together for AX6 at the middle and use the ends. Transformers are sold under RMS voltage, the voltage shown on schematics on here are peak voltage, 1.4X rms voltage - two diode drops. You want about 450-500 VA transformer for stereo amp with single output transistor pair.
In gereral safety for newbies, don't use two hands on the circuit with the power on. One hand is safe up to 100 v 20 ma source. (not the AC mains input) two hands, 25 ma across your heart can stop it. Wear no rings or jewelry on hands, wrists or neck. 1 v @ 20 a can burn your flesh to charcoal. Wear safety glasses especially soldering desoldering, solder splashes and parts can explode. Use a 100 w incandescent bulb series the AC input to the transformer when testing, up to 2 watts output. Dont work power on distracted by media or people talking to you.
I really like the AX6 design:

It seems to operate on a single supply, which is great.

It employs fewer components and transistors, simplifying the circuit.

I appreciate that there's no need for a variable resistor to adjust DC bias.

However, my main concern is the availability of the transistors. Is there an updated schematic that uses more modern transistors? I don't mind if they're only available in SMT packaging; I just prefer the idea of using relatively newer transistors in the design.
 
Regarding the other issue, there are more people with autism on this forum. I'm one of them, and I know of several others who are either diagnosed with autism or have the strong suspicion that they are autistic. Whether it will help or hinder you when you make your own equipment depends on what traits you have and how strong they are. The typical autistic attention to details can sometimes be quite benificial.
Predominantly inattentive ADHD, Sensory processing sensitivity, Autism spectrum, definitely one, possibly all three. Psychiatry is subject to fashion, in addition psychiatrists individually have their favorite diagnosis. I never asked to make it official, on the contrary. I rarely inform people about it, it's my personal battle.
 
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After much thinking, I think the AX6 might just be one of the coolest amp designs for people starting out. It could be cool to use a simpler class D IC amp with fewer parts, but I was really excited about making a complete discrete amplifier.

However, I still have some questions:

What's the ideal power input and output for this amp? Would a basic 90W 12V power supply do the trick? I have one sitting on my workbench gathering dust.

I did read some parts of that thread you shared, but I have to admit, it's a bit tough to get through.

I'm really thankful for all the advice you've given me so far, and I apologize for reaching out so much. My situation tends to lead me to uncertainty in a way that's hard to explain. I know it's because I'm not quite there in terms of fully grasping the electronics concepts, and I appreciate your patience with me
 
Predominantly inattentive ADHD, Sensory processing sensitivity, Autism spectrum, definitely one, possibly all three. Psychiatry is subject to fashion, in addition psychiatrists individually have their favorite diagnosis. I never asked to make it official, on the contrary. I rarely inform people about it, it's my personal battle.
I've never received an official diagnosis, but I'm quite confident that I have autism and ADHD. This is the first time I've opened up about it to anyone. I'm nearly 50 years old, and this has been an immense weight on my shoulders—a relentless struggle against my inner struggles.

Only someone who's on the spectrum truly understands what lies within us. No doctor or scientist can fully comprehend the intricacies of dealing with autism.
 
@Prognosis2811 -

Oh; some of us have a developed appreciation though; I'm an architect in the UK,and perhaps unsurprisingly - it's a profession with rather above-average neuro-diverse % of members.

OTOH - I work closely, daily with colleagues with issues acknoledged or tacit across the spectrum from v. mild Asperger's to ADHD: and we get along realy , really well; mutual support, recognition of each persons skills and interests - and presence: it's an open conversation at the place I work! And one of my friends of many years has only just been diagnosed - at 45. We were both surprised by that , but once Ger started explaining how he noticed..Hmm, well... I don't think I am, but have never tested (despite having a weird fascination with number theory and topology and... a stupid memory for detail/data, retained in perpetuity)

So - Take heart - you are not alone, and ...we... appreciate it is different for everyone.

Welcome to DIYaudio
 
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Regarding the 2N3773... I've developed quite an affinity for using Easyeda as my go-to platform for crafting schematic diagrams. It truly excels in facilitating the creation of those intricate blueprints that I find so satisfying. Regrettably, venturing into the realm of producing entirely new diagrams is not exactly within my comfort zone. The process demands a significant investment of time and a particular skill set that, truth be told, can present a formidable challenge for me.

So, there I was, engrossed in the process of meticulously working on a particular diagram. It was an endeavor that seemed quite straightforward at first, but soon enough, I encountered a noticeable increase in complexity. You see, this diagram displayed a trio of pins, or at least, something that closely resembled pins – a configuration I hadn't encountered previously. It was an unfamiliar symbol, and the uniqueness of it was quite apparent.

Now, let's talk about the actual component itself, the BJT (Bipolar Junction Transistor) known as the 2N3773. In its physical form, this BJT sports a total of three pins. This piece of information intrigued me, given the aforementioned symbol. What puzzled me was the alignment of what I observed in reality with what I had expected based on the symbol's representation.

And here's where the intrigue deepens: this particular BJT goes by the classification of an NPN type. This acronym stands for "Negative-Positive-Negative," which indicates the arrangement of the layers within the transistor. So, in essence, it's a type of BJT that involves the flow of current from the emitter to the collector, controlled by the current at the base.

All these observations have left me somewhat bewildered. My initial assumption was that I might encounter more pins on the BJT component, given the intricate nature of the diagram's portrayal. However, reality painted a different picture, leading me to question whether this BJT is indeed an NPN variant. Your insights on this matter would be greatly appreciated, as I seek to reconcile the disparity between my expectations and the practical aspects of the 2N3773's design.




1692387506213.png
1692387541179.png
1692387802546.png
 
After dedicating a substantial three-hour chunk of time to what appeared to be a rather straightforward endeavor – the layout of a modest handful of components – I find myself with a result that, while not entirely dissimilar to my envisioned outcome, doesn't quite meet the level of satisfaction I had anticipated.

Having said that, I want to underscore my willingness to remain open to suggestions, recommendations, and insights from others who might have a fresh perspective or innovative ideas. This layout, as it stands, is far from final, and I'm committed to harnessing collaborative input to propel it towards a state of higher accomplishment and alignment with my original vision.

I'm refraining from sharing the schematic at this moment. The reason behind this decision lies in the fact that the current representation is quite far from being optimally structured. It's apparent that what I've generated has unintentionally morphed into a rather complex labyrinth of components, where the risk of getting lost within the intricacies is quite high.

3D_PCB1_2023-08-18.png