Hello everyone, this is my first thread, I just finished experiment built gu29 hybrid amplifier. This is the first tube power amplifier I built. For the output transformer I used a regular toroid power transformer because the output transformer for tube amplifiers is very expensive and hard to find in my area. This amplifier circuit is a combination of several circuit parts that I saw in this forum and on the web. I'm just an ordinary hobbyist, so I only have a multitester and a cheap pocket oscilloscope, so I can't measure the frequency response or THD of this amplifier, combined with my 6p1p preamp, this amplifier sounds good (according to my ears), the bass sounds solid and deep like solid state amplifiers. So, according to experts, can this amplifier circuit still be improved and optimized?
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Interesting. I have not seen an active load on the output stage of a parafeed amp before. I'm curious about the 2SK2654 circuit from anode to ground. What is its purpose?
It's interesting to see the size of the heatsinks you are using. I also see two fans. Are they cooling the heatsinks? It's tough getting rid of all that heat.
ray
It's interesting to see the size of the heatsinks you are using. I also see two fans. Are they cooling the heatsinks? It's tough getting rid of all that heat.
ray
The transistor in parallel with the power tube would do most of the job , making the tube almost useless as an output device ... just an expensive and wasteful driver .
@ratbagp
hi Mr. Ray, actually I wanted to build this GU29 amplifier after seeing the 829b incandescent bulb amplifier on your blog. The fan is helping cool the heatsink. Because this is still in the experimental stage, I used the ex-CPU heatsink that I had to reduce costs. The 2SK2654 circuit from anode to ground, its function is to increase the current capability of the GU29 so that the output power also increases, I took the idea from Mr. Broskie's blog about the "supercharged output stage". Yesterday I added a mosfet source follower + ccs circuit between the 6N1P and GU29 and it really raised the sound quality to a new level. When I have some free time later, I will assemble the circuit to a pcb and give it a suitable casing.
hi Mr. Ray, actually I wanted to build this GU29 amplifier after seeing the 829b incandescent bulb amplifier on your blog. The fan is helping cool the heatsink. Because this is still in the experimental stage, I used the ex-CPU heatsink that I had to reduce costs. The 2SK2654 circuit from anode to ground, its function is to increase the current capability of the GU29 so that the output power also increases, I took the idea from Mr. Broskie's blog about the "supercharged output stage". Yesterday I added a mosfet source follower + ccs circuit between the 6N1P and GU29 and it really raised the sound quality to a new level. When I have some free time later, I will assemble the circuit to a pcb and give it a suitable casing.
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There are so many interesting Broskie articles it is difficult to remember a fraction of them. I'm glad you tried the 'supercharged' idea.
supercharged output stage
also
https://www.tubecad.com/2013/04/blog0259.htm
I also found George's (Tubelab) Powerdrive (mosfet follower) made driving a 6V6 or even a GK-71 much better.
http://tubelab.com/articles/circuits/power-drive/
I will be interested to see your final schematic.
ray
supercharged output stage
also
https://www.tubecad.com/2013/04/blog0259.htm
I also found George's (Tubelab) Powerdrive (mosfet follower) made driving a 6V6 or even a GK-71 much better.
http://tubelab.com/articles/circuits/power-drive/
I will be interested to see your final schematic.
ray
@ratbagp
hi mr Ray, the current schematic will be include a mosfet follower. When i'm free i will re-draw it using software. i am not using power-drive circuit because I have no plans to drive it into class A2. Now I have to collect all the parts needed and of course a proper casing. I even have idea to diy socket for Gu29.
hi mr Ray, the current schematic will be include a mosfet follower. When i'm free i will re-draw it using software. i am not using power-drive circuit because I have no plans to drive it into class A2. Now I have to collect all the parts needed and of course a proper casing. I even have idea to diy socket for Gu29.
