While the print says 2K2 there's a 4K7 resistor in his spot. It's probably the cathode resistor of the input tube, running it less hot. Bypassing the cathode resistor raises gain and lowers output impedance.
Hi - does anyone have a source for A10/A12 OUTPUT transformers - the so-called "uprated" ones? They are encapsulated so not as plentiful on the usual places. The original amp suppliers want an absolute fortune for them no not going there. I want to use an existing A10 chassis (bare) which is pre-drilled. I no longer have my A10 as sold it a few years ago to go for a Yaqin MC100B.
Encapsulated is my preference for better aesthetics, rather than trying to mount a non-encapsulated with wires showing.
Many thanks in advance 🙂
Encapsulated is my preference for better aesthetics, rather than trying to mount a non-encapsulated with wires showing.
Many thanks in advance 🙂
Well, I am learning in fast pace. Modding an amp is easier than I thought. Especially with all the great tutors and tutorials.
While working on the BRZHIFI A20, I have learned the Reisong A10 was initially designed for 6v6 tubes. Link to forum
The EL34 Cathode resistors were already lowered to 300Ohm/3w to accomodate a better voltage in the BRZHIFI A20.
I also learned the cathode resistors in the pre-amp stage for the 6n2 tubes are 4k in the BRZHIFI instead of the 2k on the Reisong . While modding the amp I discovered why. I must say the engineer at BRZHIFI did a pretty decent job getting most out of the amp within the given pricepoint and task at hand. He also cleverly masked some weaker points of the amp that unveiled themselves while upgrading the amp.
The BRZHIFI A20 is already in triode mode out of the factory. I can only conclude the BRZHIFI A20 is the better version of the A10, purely looking at the schematics and the design choices made by the manufacturer already. It even came with a Russian rectifier tube over the Chinese one in the A10.
Modifications I have done in the chonological order
1) Replace coupling caps
I have replaced the stock Vishay 220nf with Auricap XO 220nf versions.
The sound cleared up dramatically and the frequency response and sustain below 100Hz got completely resored, as also the higher frequencies became better audible. It sounds super smooth, but something also went missing!
It became clear the amp had some more flaws to adress.
While the dynamics had been restored now, the amp now sounded lifeless. As it the soul was drained by some dementors. Also I noticed a lot of unpleasant distortion going on in the upper ranges (above 10khz). It also became clear the engineer at BRZHIFI matched all the parts in such a way to get the most out of the amp voice wise. The stock coupling caps provided the "soul" to the voices which was now gone. Also the stock caps were more rolled of the in the lower and higher frequency band, masking some flaws in the amp.
I'd say this was about a 40% improvement over the stock caps despite the amp losing it's "soul".
2) Bypassing EL34 cathode resistor
I read that bypassing the cathode resistor increases gain and can deliver better sound. I installed some 2000uf Cambridge Audio (probably rebranded Nichicon) caps. Immediately the soundstage came more to life due to 2nd harmonic distortion. It was about a 15% improvement.
2) Experimenting with different cathode resistor values on the chinese 6n2 's
I read that the Reisong A10 is using a probably too high value in it's pre-amp stage running the 6n2's quite cold. The Reisong A10 uses 2k resistors, the BRZHIFI uses 4k resistors which are bypassed.
I experimented with different values: 840 Ohm, 1k and 2k.
Based on this article I installed the 840 Ohm resistor. While I noticed an improvement in the 2nd harmonic, it became VERY clear the 6n2's are the limiting factor in further upgrading the sound. While the 2nd harmonic had increase, also have all the other distortions resulting in an even more muddy sound and more distortion in the higher end of the spectrum.
I reverted back to the original value of 4k.
3) Replacing the Chinese 6n2 with Voskhod 6n2-ev
While working on this amp, I ordered some NOS Voskhod 6n2-ev 's. I read that they should improve the soundstage and give better treble. Both things that the stock ones are missing.
When I finally received them, I noticed the immense difference in the build quality. The Voskhod is built way better overal. This looks promising!
In installed them, using the stock 4k cathode resistor. Wow! What a difference that made! Not only did the holographic image improve, also did indeed the higher end of the frequency spectrum. Also the unpleasant distortions are gone as far as I can hear!
This made a 60% improvement in the system.
4) Lowering cathode resistor value on the Voskhod 6n2-ev
Now with better tubes installed, I decided to lower the cathode resistor values once again.
I decided to go for 1k as skunkie uses this in her A10 / A12 modification.
And wow did this improve the sound enormously! The voices are really singing like they are in my room.
The holographic image improved a little also. And best of all: No added unpleasant distortion. The sound is very clear.
Overall I would say this is another 60% improvement over simply replacing the tubes.
Overall impressions in retrospect:
I'd say this is a nice amp to learn the basics of tube amp design. It was at least for me. As you can see in the pictures I also own a Thule Spirit IA60. Great solid-state amp which I use as a reference. With the mods done I am very impressed of that the BRZHIFI A20 can deliver. When I first got the amp, I could not decide which one to keep. I decided to keep the BRZHFI A20 to see if it would grow on me. But something still was missing. After the mods that might actually change! I will give it some more days and that will switch back to the Thule to see which I like better. Ofcourse the Thule is "better" in every single way on paper. It has wayyy more power, wayyyy better highs. But it does not have a "soul" like the BRZHIFI A20 does now. I guess that simply comes down to 2nd harmonic distortion.
Some pictures:
While working on the BRZHIFI A20, I have learned the Reisong A10 was initially designed for 6v6 tubes. Link to forum
The EL34 Cathode resistors were already lowered to 300Ohm/3w to accomodate a better voltage in the BRZHIFI A20.
I also learned the cathode resistors in the pre-amp stage for the 6n2 tubes are 4k in the BRZHIFI instead of the 2k on the Reisong . While modding the amp I discovered why. I must say the engineer at BRZHIFI did a pretty decent job getting most out of the amp within the given pricepoint and task at hand. He also cleverly masked some weaker points of the amp that unveiled themselves while upgrading the amp.
The BRZHIFI A20 is already in triode mode out of the factory. I can only conclude the BRZHIFI A20 is the better version of the A10, purely looking at the schematics and the design choices made by the manufacturer already. It even came with a Russian rectifier tube over the Chinese one in the A10.
Modifications I have done in the chonological order
1) Replace coupling caps
I have replaced the stock Vishay 220nf with Auricap XO 220nf versions.
The sound cleared up dramatically and the frequency response and sustain below 100Hz got completely resored, as also the higher frequencies became better audible. It sounds super smooth, but something also went missing!
It became clear the amp had some more flaws to adress.
While the dynamics had been restored now, the amp now sounded lifeless. As it the soul was drained by some dementors. Also I noticed a lot of unpleasant distortion going on in the upper ranges (above 10khz). It also became clear the engineer at BRZHIFI matched all the parts in such a way to get the most out of the amp voice wise. The stock coupling caps provided the "soul" to the voices which was now gone. Also the stock caps were more rolled of the in the lower and higher frequency band, masking some flaws in the amp.
I'd say this was about a 40% improvement over the stock caps despite the amp losing it's "soul".
2) Bypassing EL34 cathode resistor
I read that bypassing the cathode resistor increases gain and can deliver better sound. I installed some 2000uf Cambridge Audio (probably rebranded Nichicon) caps. Immediately the soundstage came more to life due to 2nd harmonic distortion. It was about a 15% improvement.
2) Experimenting with different cathode resistor values on the chinese 6n2 's
I read that the Reisong A10 is using a probably too high value in it's pre-amp stage running the 6n2's quite cold. The Reisong A10 uses 2k resistors, the BRZHIFI uses 4k resistors which are bypassed.
I experimented with different values: 840 Ohm, 1k and 2k.
Based on this article I installed the 840 Ohm resistor. While I noticed an improvement in the 2nd harmonic, it became VERY clear the 6n2's are the limiting factor in further upgrading the sound. While the 2nd harmonic had increase, also have all the other distortions resulting in an even more muddy sound and more distortion in the higher end of the spectrum.
I reverted back to the original value of 4k.
3) Replacing the Chinese 6n2 with Voskhod 6n2-ev
While working on this amp, I ordered some NOS Voskhod 6n2-ev 's. I read that they should improve the soundstage and give better treble. Both things that the stock ones are missing.
When I finally received them, I noticed the immense difference in the build quality. The Voskhod is built way better overal. This looks promising!
In installed them, using the stock 4k cathode resistor. Wow! What a difference that made! Not only did the holographic image improve, also did indeed the higher end of the frequency spectrum. Also the unpleasant distortions are gone as far as I can hear!
This made a 60% improvement in the system.
4) Lowering cathode resistor value on the Voskhod 6n2-ev
Now with better tubes installed, I decided to lower the cathode resistor values once again.
I decided to go for 1k as skunkie uses this in her A10 / A12 modification.
And wow did this improve the sound enormously! The voices are really singing like they are in my room.
The holographic image improved a little also. And best of all: No added unpleasant distortion. The sound is very clear.
Overall I would say this is another 60% improvement over simply replacing the tubes.
Overall impressions in retrospect:
I'd say this is a nice amp to learn the basics of tube amp design. It was at least for me. As you can see in the pictures I also own a Thule Spirit IA60. Great solid-state amp which I use as a reference. With the mods done I am very impressed of that the BRZHIFI A20 can deliver. When I first got the amp, I could not decide which one to keep. I decided to keep the BRZHFI A20 to see if it would grow on me. But something still was missing. After the mods that might actually change! I will give it some more days and that will switch back to the Thule to see which I like better. Ofcourse the Thule is "better" in every single way on paper. It has wayyy more power, wayyyy better highs. But it does not have a "soul" like the BRZHIFI A20 does now. I guess that simply comes down to 2nd harmonic distortion.
Some pictures:
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I've browsed through many forums from different parts of the world and saved all the information. This is my first experience with a tube amplifier and an attempt to do something better understanding what you're doing. I decided to talk to the GPT chat. Here's my dialogue and advice:
Modification and Optimization of Reisong A10 for Better Soundstage and Realism
1. Optimization of the Input Stage (V1, V4 - 6N2P-EV)
Anode Resistor (R103, R203)
- The current value is 75kΩ, which slightly reduces gain and provides a softer sound.
- Suggested value: 100kΩ – 120kΩ (e.g., Allen Bradley or Vishay Dale).
- Power rating: 0.5W – 1W is sufficient.
Cathode Resistor (R101, R201)
- Replaced 10kΩ with 1.2kΩ, which improved dynamics and microdetail.
- Lowering this value further may lead to excessive gain and distortion.
Cathode Capacitor (C104, C204 - missing on the schematic)
- Adding 100µF – 220µF / 25V (preferably Nichicon, Elna, or Black Gate) can improve bass response and midrange clarity.
2. Output Stage (V2, V5 - EL34) Optimization
Cathode Resistor (R108, R208)
- Stock value: 500kΩ → replaced with 330kΩ, which provided a more balanced and magical sound.
- Experimenting with 250kΩ – 330kΩ affects harmonic balance and overall texture.
Cathode Resistor for EL34 (R106, R206)
- Some suggest 2kΩ, but it depends on desired sound.
- Suggested range:
- Warm, full-bodied sound: 270Ω – 300Ω (higher bias, stronger bass).
- Balanced, 3D soundstage: 330Ω – 360Ω (recommended).
- High detail and airiness: 390Ω – 470Ω (cleaner but slightly thinner).
Bias Current for EL34 (Best Soundstage & Naturalness)
- Best balance: 55 – 60mA (Cathode voltage: 22V – 24V).
- Detailed & airy sound: 50 – 55mA (Slightly less bass).
- Warm & powerful sound: 65 – 75mA (More bass, slightly compressed stage).
The best compromise is 330Ω – 360Ω for the cathode resistor with 55 – 60mA bias current for a natural, realistic, and immersive soundstage.
///////////////////////////////////////////////////////////////////////////////////////////////
Modifications and Optimization of Reisong A10 for 3D Soundstage and Realistic Tone
1. Input Stage Optimization (V1, V4 - 6N2P-EV in Parallel Mode)
The 6N2P-EV tubes are wired in parallel mode, which affects the choice of resistor values for achieving the best sound balance.Anode Resistor (R103, R203)
- Stock value: 75kΩ (reduces gain, softer sound).
- Suggested values for best 3D sound and realism:
- 33kΩ – 39kΩ (Vishay Dale, Allen Bradley, Amtrans).
- 33kΩ → Warmer, denser sound.
- 39kΩ → More air, detail, and spaciousness.
Cathode Resistor (R104, R204)
- Suggested values:
- 1kΩ – 1.2kΩ
- 1kΩ → Maximum transparency and openness.
- 1.2kΩ → Slightly warmer and smoother sound.
Cathode Capacitor (Optional, Not Shown in Schematic)
- 100µF – 220µF / 16–35V(Elna Silmic II, Nichicon Muse).
- If removed → more micro-detail, but thinner bass.
- If added → wider soundstage and richer tone.
2. Output Stage Optimization (V2, V5 - EL34)
Cathode Resistor for EL34 (R108, R208)
- Stock value: 500Ω → Produces soft, warm sound but lacks dynamics.
- Experimentally tested values:
- 330Ω – 360Ω (recommended).
- 270Ω – 300Ω → More powerful bass, but slightly compressed stage.
- 390Ω – 470Ω → More clarity, but slightly leaner bass.
Optimal Bias Current for Best Soundstage & Naturalness
- Best balance: 55 – 60mA (Cathode voltage: 22V – 24V).
- Maximum detail & airiness: 50 – 55mA.
- Warm & dynamic sound: 65 – 75mA (More bass but slightly less spaciousness).
The best compromise is 330Ω – 360Ω for the cathode resistor with 55 – 60mA bias current, resulting in a natural, realistic, and immersive soundstage.
3. Additional Modifications for Improved Sound Quality
Removal of R301
- Removing R301 (feedback resistor) resulted in a more open and dynamic sound.
Replacement of R302 (8.2kΩ → 4.3kΩ)
- Lowering R302 increased dynamics and improved clarity.
R101 Change (10kΩ → 1.2kΩ)
- Resulted in better micro-detail and more natural tone.
Optimizing R106 (2kΩ option)
- Some suggest using 2kΩ for improved midrange clarity, but the effect varies.
Final Recommendations for the Best Sound Experience
🔹 For a 3D soundstage and realism:- 6N2P-EV in parallel mode with 33kΩ – 39kΩ anode resistor & 1kΩ – 1.2kΩ cathode resistor.
- EL34 cathode resistor 330Ω – 360Ω for balanced dynamics and air.
- Bias current 55 – 60mA for optimal warmth and clarity.
- Increase EL34 cathode resistor to 390Ω – 470Ω.
- Remove cathode bypass capacitor for more transparency.
- Use 270Ω – 300Ω cathode resistor for EL34.
- Add 220µF – 1000µF cathode capacitor for more body and low-end presence.
This summary covers the optimal modifications for Reisong A10 to achieve maximum realism, spatial depth, and transparency. Let me know if you need any refinements! 🎵🔥
How Anode Current and Cathode Resistor Affect Sound in 6N2P-EV (Parallel Mode) Reisong A10
1. The Role of Anode Current (Ia) in Sound Quality
The anode current significantly impacts the soundstage, detail, and overall realism of the amplifier. Here’s how different anode currents affect sound:| Anode Current (Ia per triode) | Sound Characteristics |
|---|---|
| Too low (below 3mA per triode, ~6mA in parallel mode) | Collapsed soundstage, weak dynamics, "thin" and lifeless sound. |
| Optimal range (4 – 5mA per triode, ~8 – 10mA in parallel mode) | Best balance: wide, three-dimensional soundstage, natural timbre, clarity. |
| Too high (above 6mA per triode, ~12mA+ in parallel mode) | Increased harmonics but reduced microdynamics, possible distortion and harshness. |
2. How Anode Resistor (Ra) Affects Sound
The anode resistor (Ra) sets the anode voltage and affects gain, linearity, and dynamics.| Anode Resistor (Ra) | Effect on Sound |
|---|---|
| Too high (82kΩ – 100kΩ) | Lower anode current → "colder" and more analytical sound, reduced dynamics. |
| Optimal range (33kΩ – 39kΩ in parallel mode) | Balanced anode current → natural, deep soundstage, good airiness. |
| Too low (22kΩ – 27kΩ) | Higher current → more warmth but risk of compression and loss of microdetails. |
- 33kΩ – 39kΩ for the best balance of three-dimensional sound and natural tonality.
- Voltage drop across Ra should be around 140V – 160V for optimal operation.
3. The Effect of the Cathode Resistor (Rk)
The cathode resistor sets the bias point, affecting dynamics, timbre, and openness of sound.| Cathode Resistor (Rk) | Effect on Sound |
|---|---|
| Too low (330Ω – 470Ω in parallel mode) | Higher gain, more dynamics, but possible loss of smoothness. |
| Optimal range (1kΩ – 1.2kΩ in parallel mode) | Best tonal balance, natural warmth, open and airy sound. |
| Too high (2kΩ – 2.4kΩ in parallel mode) | Lower gain, increased clarity, but risk of analytical or sterile sound. |
- 1kΩ – 1.2kΩ → best three-dimensional sound, natural realism.
- Cathode voltage should be ~1.5V – 2.5V for optimal biasing.
4. Measuring Anode Current and Biasing
To ensure the tube is operating in its optimal range, measure anode voltage and current:✔ Anode voltage (Va):
- Should be 150V – 180V (if B+ = 300 – 310V).
- Measure voltage across Ra (anode resistor) and calculate:
✔ Cathode voltage (Vk):
- Should be 1.5V – 2.5V for proper biasing.
5. Summary: Best Settings for 6N2P-EV (Parallel Mode)
| Parameter | Recommended Value |
|---|---|
| Anode Resistor (Ra) | 33kΩ – 39kΩ |
| Cathode Resistor (Rk) | 1kΩ – 1.2kΩ |
| Anode Voltage (Va) | 150V – 180V |
| Cathode Voltage (Vk) | 1.5V – 2.5V |
| Anode Current (Ia, per triode) | 4 – 5mA (8 – 10mA total per tube) |
Let me know if you need more details! 😎chat GPT
Removing R301 (10Ω) in Reisong A10 Power Supply: Effects and Solutions
🔹 Ripple Reduction – It acted as a damper between the rectifier and capacitor, helping to reduce ripple.🔹 Inrush Current Limiting – It protected the rectifier from sudden current spikes.🔹 Noise Suppression – It reduced high-frequency ringing in the power supply.
🔹 Recommended choke specifications:
✅ Better dynamics and bass response.
✅ Lower noise and hum.
✅ Smoother operation of the rectifier.
🔹 Option 1: Increase Resistance
For soft start and tube protection, use CL-90 (or similar NTC thermistor 47Ω/2A).📌 Effect:
✅ Gradual startup.
✅ Protects diodes and capacitors.
2️⃣ If a choke is not feasible, use 22–47Ω (2–5W) for protection.
3️⃣ For smooth startup, an NTC thermistor (CL-90, 47Ω/2A) is a great option.
💡 Removing R301 without replacement increases noise and shortens 5AR4 lifespan. A choke or resistor upgrade will significantly improve performance! 🔥
Question:
I removed R301 (10Ω) in the power supply of my Reisong A10 as some people suggested. I would like to understand how this affects the amplifier and whether I should replace it with something else for better performance.1. What Was the Purpose of R301 (10Ω)?
This resistor was placed after the rectifier (5AR4) and before the first filter capacitor C301 (100μF). It had several important functions:🔹 Ripple Reduction – It acted as a damper between the rectifier and capacitor, helping to reduce ripple.🔹 Inrush Current Limiting – It protected the rectifier from sudden current spikes.🔹 Noise Suppression – It reduced high-frequency ringing in the power supply.
2. What Happens When You Remove R301?
✅ Pros:- Slightly higher B+ voltage (~2–3V increase), which may subtly affect tonal balance.
- Less power loss, but not significant.
- Higher inrush current, which can shorten the lifespan of 5AR4.
- Increased ripple, especially with a 100μF first capacitor.
- Potential high-frequency noise, affecting amplifier clarity.
3. Best Replacement for R301 (10Ω)
💡 Optimal solution – Use a choke instead of R301!This improves filtering and provides a cleaner power supply.🔹 Recommended choke specifications:
- 2–10H, 100–200mA, resistance 50–200Ω.
- Example: Hammond 159P (10H, 125mA), 193H (5H, 200mA).
✅ Better dynamics and bass response.
✅ Lower noise and hum.
✅ Smoother operation of the rectifier.
4. Alternative Solutions If a Choke Is Not an Option
If adding a choke is difficult, reinstalling R301 but with a different value can still improve performance.🔹 Option 1: Increase Resistance
- Instead of 10Ω, use 22–47Ω (2–5W, metal film).📌 Effect:
✅ Reduces inrush current.
✅ Protects 5AR4.
✅ Slightly lowers ripple.
For soft start and tube protection, use CL-90 (or similar NTC thermistor 47Ω/2A).📌 Effect:
✅ Gradual startup.
✅ Protects diodes and capacitors.
Conclusion:
1️⃣ Best choice – Replace R301 with a 5–10H choke for cleaner power and better sound.2️⃣ If a choke is not feasible, use 22–47Ω (2–5W) for protection.
3️⃣ For smooth startup, an NTC thermistor (CL-90, 47Ω/2A) is a great option.
💡 Removing R301 without replacement increases noise and shortens 5AR4 lifespan. A choke or resistor upgrade will significantly improve performance! 🔥
LOL!!!! I've shown what happens both on a scope and using THD measurements as well as the actual power output. This AI tool found all the nonsense people who don't understand tube electronics have posted on forums about this amp.
This is my first experience with the Raisong A10 tube amplifier. A couple of weeks ago I didn't know what an anode and a cathode were and how it works. I read a lot of forums on how to set up an amplifier.
I have Russian 6n2p tubes Raisong A10, not A12.
Once I put 330 ohm El34 in the cathode instead of 250 ohms and something really happened, that the music I didn't like this time sounded so loud that I couldn't tear myself away and didn't want to turn it off. I started digging further.I tried the GPT chat. It turned out to be interesting with this GPT piece of iron, it explains everything and most importantly not only the calculations and other parameters, but it knows what influences occur on the sound, which is rarely said on the forums.
I uploaded the Raisong A10 circuit to him and wrote that I changed it and he really sees and reads it. This has never happened with this "smart guy" before.
What can I say, GPT helps but with an amendment like after drinking 6 packs of beer, it can drive away nonsense..He recommended that I raise the anode current in the tube to 4.5 mA and also told me that at 6 mA there will be a more corporeal sound, but then there was a problem, 6n2p has only 2.3 mA on one side maximum. I told him, he apologized and said that I was right.
6n2p and 12AX7 have differences.
2.3 mA 6n2p and 12AX7 1.2 mA.
The internal resistance of 6n2p is 50 kOhm, 12AX7 62 kOhm.
I searched on different forums for the best music mode for 6n2p tubes and the information is different, some Russians suggest setting it up through a program by adjusting the number of harmonics with a cathode resistor, reducing distortion for each tube separately, and they got an anode resistor from 100 kOhm to 500 kOhm, different operating modes, and an anode current of about 0.8 mA.
How this affects the sound is not a word.
Today, there is a lot of audio equipment with super characteristic , but it is impossible to listen to.
Who can tell me what parameters should be in a parallel-connected 6n2p triode for better musicality and realism of sound with a three-dimensional scene?
What is the anode current?
What is the voltage on the anode if B + 310V
What is the voltage on the cathode?
Thank you
Chat GTP doesn't "know" anything, it's simply regurgitating what it found on some online forum from people who don't know what a cathode or an anode is either.
Why do you think that 6N2P is the weakest point of this amp?
If you read the whole topic from the beginning, you can see that several modification exists.
The next question is will CGPT use this forum post as more ''truth'' for another question it receives about the amp? Everyone who posts what its response is for something creates an echo chamber CGPT uses for research and its replies to people. How many echoes of BS does it take to become a ''fact?''
I play with different modes of the input tube and listen to what happens. I ask everyone to understand that my system is too complex, two A10 amplifiers work after active crossovers and not on one speaker per channel.
Here is my last dialogue with the GPT as an example.:
I found an old recording of what resistors were on the 6n2p tube and the parameters and I really liked the sound then, it became such that I could not tear myself away from any, even the most boring music.
In the anode 216v 1.02mA in the cathode 2.13v
GPT answers:
Interesting parameters! If you liked the sound then, let's figure out why this particular mode gave a good result and how it can be improved.Mode analysis:Anode voltage: 216VHigh enough for a good dynamic range.Anode current: 1.02 mA Low current → gives airiness, but can weaken the dynamics.Cathode voltage: 2.13VQuite a high bias, which reduces the gain, but reduces distortion.Anode resistor (approximately): 100-120 kOhmIn this mode, such anode resistance will give high gain, but with a soft attack.Cathode resistor (approximately): 2 kOhmHigh value → reduces current, but makes the sound more open.Why might you like the sound?Transparency and airinessLow anode current and high anode resistor give an open, detailed sound.Clarity and clarity in the midrangeHigh cathode bias reduces overload, making the sound cleaner.Good balance between softness and detailThis mode does not overload the tube, but leaves the volume in the sound.What can be tried to improve?If you want a bit more dynamics (drum hit, density), you can increase the anode current a bit to 1.3-1.5 mA.This can be done by reducing the cathode resistor to 1.5-1.8 kOhm.If you want even more air and stage, you can try a cathode resistor of 2.2-2.4 kOhm, but then the gain will decrease.If you feel the sound lacks "meat", you can play with the cathode bypass capacitor (100-220 µF).
Here is my last dialogue with the GPT as an example.:
I found an old recording of what resistors were on the 6n2p tube and the parameters and I really liked the sound then, it became such that I could not tear myself away from any, even the most boring music.
In the anode 216v 1.02mA in the cathode 2.13v
GPT answers:
Interesting parameters! If you liked the sound then, let's figure out why this particular mode gave a good result and how it can be improved.Mode analysis:Anode voltage: 216VHigh enough for a good dynamic range.Anode current: 1.02 mA Low current → gives airiness, but can weaken the dynamics.Cathode voltage: 2.13VQuite a high bias, which reduces the gain, but reduces distortion.Anode resistor (approximately): 100-120 kOhmIn this mode, such anode resistance will give high gain, but with a soft attack.Cathode resistor (approximately): 2 kOhmHigh value → reduces current, but makes the sound more open.Why might you like the sound?Transparency and airinessLow anode current and high anode resistor give an open, detailed sound.Clarity and clarity in the midrangeHigh cathode bias reduces overload, making the sound cleaner.Good balance between softness and detailThis mode does not overload the tube, but leaves the volume in the sound.What can be tried to improve?If you want a bit more dynamics (drum hit, density), you can increase the anode current a bit to 1.3-1.5 mA.This can be done by reducing the cathode resistor to 1.5-1.8 kOhm.If you want even more air and stage, you can try a cathode resistor of 2.2-2.4 kOhm, but then the gain will decrease.If you feel the sound lacks "meat", you can play with the cathode bypass capacitor (100-220 µF).
There are enough people that have done the Skunkie mod, and are happy with it, to recommend it. She also backs it all up in measurements. See her videos on YouTube.
Thanks of course I watched, Thanks Stephe, this video is where the purchase and knowledge of the tube amplifier all started.
But I don't have an A12, but an A10 with a 6n2 Tube. (6n2p) made a Skunkie mod but without feedback, listened, then connected a generator and an oscilloscope and played with different resistor values, learning the world of the tube, ....The tube can be driven into different modes and get a sound that differs from each other, just as the sound stage changes, this is exactly what I was interested in, the effect of different modes on the sound, but there was no information anywhere about what happens to the sound when changing modes. Guy Chat GPT this time turned out to be more useful than many forums.
Without the Schade feedback loop, it's not going to sound good and all bets are off. I know for a fact it's going to sound overly bright, edgy, and overall very fatiguing. I explain in DETAIL how this resistor value can be used to tune the sound output of the amp to your taste.
And again Chat GPT is repeating the nonsense folks who know absolutely nothing about electronics used to post on forums on how to improve this amp before I investigated this amp and found a good solution. They were just throwing parts into it with no idea what these changes are doing. And I have no idea what you are even talking about with "Driven into different modes", it's a triode and isn't going to change from being in "triode mode" no matter what you change in the circuit.
And again Chat GPT is repeating the nonsense folks who know absolutely nothing about electronics used to post on forums on how to improve this amp before I investigated this amp and found a good solution. They were just throwing parts into it with no idea what these changes are doing. And I have no idea what you are even talking about with "Driven into different modes", it's a triode and isn't going to change from being in "triode mode" no matter what you change in the circuit.
Thank you stephe, through your videos I got acquainted with tube amplifiers. This is my first experience with the A10 amplifier thanks to you.
I will lay everything out briefly, just thoughts.
Any feedback in the amplifier kills the sound, makes it lifeless, but in terms of characteristics it will be better with feedback.
According to my experiments, different modes of the 6n2p tube create different aromas (bouquets) of harmonics and here it is important to adjust, if possible, to the specific acoustics of the house to get the most realistic, exciting sound.
This is all about different current and voltage modes by changing the anode and cathode resistors on the 6n2p tube.
The sound stage changed greatly from different modes.
Sometimes it was very wide, it was possible to narrow it and the instruments had more precise localization, sometimes it sounded very flat, sometimes three-dimensionality was revealed, you could see the instruments in depth.
Now Chat GPT or another smart guy. This helps to reduce time, elementary questions about the settings that you need to look for on the forums take a lot of time and do not result in finding something useful. At first, I dug through many forums but did not find any pattern or specifics for the modes of the 6n2p tube.
This thing Chat GPT really helps by recalculating, directing what the sound result can be, but the choice is always yours. It does not give 100% results, it is like your partner who has no hands and ears and just gives advice, but the ideological creator remains a person, and this is great for beginners.
Few people will climb with stupid questions on the forum
.You were right, the original cathode capacitor on the input tube is actually not bad and sounds good.All the options that I posted that Chat GPT offered me are an example. The only bad thing is that IA can become a god for many in the future and a complete controller of your life, where they are driving us all, complete control.
"This thing Chat GPT really helps by recalculating...", this is false information. "Chat GTP" is not recalculating not does it have any ability to audition the results of these calculations to come up with these "bouquets" it's describing. "Any feedback in the amplifier kills the sound, makes it lifeless" also isn't true, this amp with zero feedback is shrill and fatiguing.
I realize I'm not going to change your mind, this is for others who are reading. Psychoacoustics of audio is a powerful thing and likely you will now hear whatever this AI is telling you that you will hear. It appears the future may already be here for you as far as AI controlling what you are hearing.
I realize I'm not going to change your mind, this is for others who are reading. Psychoacoustics of audio is a powerful thing and likely you will now hear whatever this AI is telling you that you will hear. It appears the future may already be here for you as far as AI controlling what you are hearing.
Stephe, thank you for your work on this amp. I have bought the BOM and am about to start updating to your schematic, but I had a thought. In my main amp I use an SRPP driver and wondered if it would be possible to do the same here as I am now only using half of the 12AX7. What do you think? Would it drive the EL34 any better? Thanks.