I'm a fan of the concept: the less stuff in the signal path, the better. If 1/2 of a 12AX7 will drive the output tube, why add more stuff? Of course you can do whatever you want to do, this was just my take on mods for this amp and people seem to agree it sounds good.
I think I am going to try this on my a10.
As Stephe says it is probably a backward step, but I thought I'd have a play.
Any comments or observations before I rewire my amp and give this a try?
Keep well
Hi all,
Couldn't resist myself from re-engaging on this topic.
Thanks to the very helpfull vids from Stephe I fully rebuilt the Reisong A10 (same as the Boyuu thing).
Maybe Stephe might remember some forum posts I made over at her website haha.
I fully agree with Stephe with the "less in the signal path the better". Along with famous designer Dieter Rams: "Less, but better". So we should aim for as little components or "design" as possible. But that what we have should be of the best quality possible.
I did extensive testing and measurements on everything.
I fully agree with Stephe that feedback is needed to make it sound proper. On the other hand I find myself going to triode mode without any feedback in some very specific cases (female vocals with some light jazz or instruments). But 95% of the time I am in Ultra Lineair mode with feedback.
The focus for me was flexibility. So clean and powerfull for movies and general use, and a "triode" mode for the sake of it which happen to be my go-to for music from Laufey. My end result:
Schade feedback worked wonders on this amp. Eventually I settled on a full feedback loop starting at the output transformer all the way back to the input stage, but only when I decided to completely rework the amp to my own tastes.
Noise was a thing the Reisong A10 produced. With the full rebuild it completely went away. Dead silent on max volume. I reckon this is due to the poor isolation and circuit board these things use. Maybe the point to point wired version does not have this issue.
I have tested extensively with all kinds of settings.
1. Non-inductive wire wound cathode bias resistors. I get measurably lower distortion, but it is really the last several percent. The biggest changes come from properly setting up the amp in the first place. Metal film (using several in parallel for heat dissipation) comes very close also. If possible do not use regular conductive wire wound cathode resistors.
2. Case is bought from Ali Express.
3. VU driver is pre bought using a TS-VU003. I also use the LED connector for it to drive the Power LED.
4. Power supply is integrated. I have tested the design intensively in a prototype case and barely got above 35 degrees Celsius. Being in the case it barely gets warm. The case dissipates the heat very well. I might add some vents in the future, but it works great for now.
One more thing...
A grood friend from the dad of the bass player in our band is a well renowned audio technician in The Netherlands. He builds speakers himself amongst other stuff and worked with some famous muscicians. He was deeply impressed with the final design I shared with you here when we tried it extensively at his place. What should be a technical show-off of like 30 minutes ended up in a listening session of a couple of hours.
So if he says it is good, I better believe it is, and I owe it all to Stephe. Thanks again!
Couldn't resist myself from re-engaging on this topic.
Thanks to the very helpfull vids from Stephe I fully rebuilt the Reisong A10 (same as the Boyuu thing).
Maybe Stephe might remember some forum posts I made over at her website haha.
I fully agree with Stephe with the "less in the signal path the better". Along with famous designer Dieter Rams: "Less, but better". So we should aim for as little components or "design" as possible. But that what we have should be of the best quality possible.
I did extensive testing and measurements on everything.
I fully agree with Stephe that feedback is needed to make it sound proper. On the other hand I find myself going to triode mode without any feedback in some very specific cases (female vocals with some light jazz or instruments). But 95% of the time I am in Ultra Lineair mode with feedback.
The focus for me was flexibility. So clean and powerfull for movies and general use, and a "triode" mode for the sake of it which happen to be my go-to for music from Laufey. My end result:
Schade feedback worked wonders on this amp. Eventually I settled on a full feedback loop starting at the output transformer all the way back to the input stage, but only when I decided to completely rework the amp to my own tastes.
Noise was a thing the Reisong A10 produced. With the full rebuild it completely went away. Dead silent on max volume. I reckon this is due to the poor isolation and circuit board these things use. Maybe the point to point wired version does not have this issue.
I have tested extensively with all kinds of settings.
- Removing and adding bypass capacitors etc. I have shared my schematics in this post : https://www.diyaudio.com/community/threads/riddle-me-this.405290/page-2. Please note I did eventually install a bypass capacitor (Nichicon KG Gold Tune 1000uF) on the el34 cathode resistor for better bass control and gain. No bypass capacitor gave me "too much" feedback which started to sound fatiguing.
- NO bypass capacitor on the 12AX7. This gives me solid local feedback in tandem with the global feedback circuit. I really like personally with my system and ears.
- I also replaced the output tubes with Gold Lion KT77.
- Went Solid State as the tube in the PSU did nothing special for me besides dropping the voltage and looking fancy. The real sound comes from the tubes anyways. The tube in the power circuit is nothing but an old-school diode.
1. Non-inductive wire wound cathode bias resistors. I get measurably lower distortion, but it is really the last several percent. The biggest changes come from properly setting up the amp in the first place. Metal film (using several in parallel for heat dissipation) comes very close also. If possible do not use regular conductive wire wound cathode resistors.
2. Case is bought from Ali Express.
3. VU driver is pre bought using a TS-VU003. I also use the LED connector for it to drive the Power LED.
4. Power supply is integrated. I have tested the design intensively in a prototype case and barely got above 35 degrees Celsius. Being in the case it barely gets warm. The case dissipates the heat very well. I might add some vents in the future, but it works great for now.
One more thing...
A grood friend from the dad of the bass player in our band is a well renowned audio technician in The Netherlands. He builds speakers himself amongst other stuff and worked with some famous muscicians. He was deeply impressed with the final design I shared with you here when we tried it extensively at his place. What should be a technical show-off of like 30 minutes ended up in a listening session of a couple of hours.
So if he says it is good, I better believe it is, and I owe it all to Stephe. Thanks again!
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Before I forget:
Japanese company Triode had an amp kit (TRK-3488) which is basically the same design. Very solid amp. You can use it as inspiratiion just as I did.
I found the shhematics for it here:
https://napple7.wixsite.com/myconsideration/post/product04
Japanese company Triode had an amp kit (TRK-3488) which is basically the same design. Very solid amp. You can use it as inspiratiion just as I did.
I found the shhematics for it here:
https://napple7.wixsite.com/myconsideration/post/product04