Early last week I said that I was going to start a new thread on the building/design of my super low THD, 1024W rms (continuous sinewave power) stereo amplifier based on the Technics “Class A+” technique for high class A power with ~one quarter the dissipation.
Some though this a good idea and encouraged it. Unfortunately I’ve been working away from home the last few days on short notice, and haven’t been able to finish the schematics for posting, so for now I’ll just post a picture of the heatsinks.
They each measure 1500 X 220 X 80 with a solid, 15mm thick base for the mounding of semiconductors. The amplifier will stand as shown in the photo (like a tower) with the heatsinks forming the left and right side panels. This way the amp will take up very little floor space.
I’ll probably get back to this thread with circuit details in a week or so.
Cheers,
Glen
Some though this a good idea and encouraged it. Unfortunately I’ve been working away from home the last few days on short notice, and haven’t been able to finish the schematics for posting, so for now I’ll just post a picture of the heatsinks.
They each measure 1500 X 220 X 80 with a solid, 15mm thick base for the mounding of semiconductors. The amplifier will stand as shown in the photo (like a tower) with the heatsinks forming the left and right side panels. This way the amp will take up very little floor space.
I’ll probably get back to this thread with circuit details in a week or so.
Cheers,
Glen
An externally hosted image should be here but it was not working when we last tested it.
Is this "Class A+" technique the one where a low power class-a amp is has it's ground swung by a high power class-b amp?
I feared it was... the design is not class-a at all and merely a waste of resources - it will only ever be as good as the class-ab ground swinging amp.
richie00boy said:
Admit it: you're just jealous of those heatsinks 🙂
The pseudo-class A Technics amps never sounded as good to me as a nice class AB...Nothing to do with real class A.
Those heatsinks are mighty big but I have doubts about their efficiency in the configuration you planned: See the vertically oriented fins loose their efficiency if they are too high since the air warms up in the "early stages" and convenction can't cool the rest of the sink. Are you going to make somekind of forced cooling scheme to that thing as well?
Anyway, seems like an interesting project and I can imagine that the amplifier "column" will look pretty awesome.
Anyway, seems like an interesting project and I can imagine that the amplifier "column" will look pretty awesome.
richie00boy said:
LOL!
I'm sorry, but that is just baloney. The design is 100% class A. Perhaps you are confusing it with something else.
Anyone interested enough in learning more can read up on it by obtaining the reference here:
http://www.diyaudio.com/forums/showthread.php?postid=1237267#post1237267
analog_sa said:
🙄
The "Class A+" amplifier is NOT "pseudo-class A". It is class A with tracking rails.
quasi said:
http://www.fastron.com.au/
teemuk said:
I have compensated for the loss in efficiency by over-specifying the size of the heatsinks. They are more that big enough, even in the vertical position. The amplifier is going to be a bridged design, so there are no less than 8 power output stages in total. The lower dissipating Class AB stages and the regulated power supplies will go towards the top of the heatsinks.
teemuk said:
Yes 🙂
I'm also building a dual trace signal monitoring oscilloscope (round CRT, green phosphor) which will be installed towards the top of the unit. The amplifier will have a gloss black front panel, several old fashioned (1940's) panel meters for montoring various things such as class A bias, supply voltages, etc, and lots of blue leds in chome bezels!
Cheers,
Glen
Glen,
great project , but I am, as are a lot of other people, concerned about the global warming implications of your 1024W linear design.
Next time the lights dip in Tokyo mate, I'll be looking south in the general direction of oz!
cheers
😀
great project , but I am, as are a lot of other people, concerned about the global warming implications of your 1024W linear design.
Next time the lights dip in Tokyo mate, I'll be looking south in the general direction of oz!
cheers
😀
G.Kleinschmidt said:
One part of the design is 100% class-a yes. But if you actually follow the current path you will see it's return is through a class-b stage, making the class-a stage pointless. So you might as well just run the class-b part.
Unless of course I am confusing this design with something else as I couldn't download the PDF without paying for it.
richie00boy said:
No, it doesn't make the class-A stage pointless at all. The class B amplifier drives the rail voltages for the class A stage. The class A stage drives the speaker. The fact that the return path is through the class-B stage hardly matter a jot.
The speaker is driven in 100% class A.
I suggest that you actually pay for the paper, which actually examines in detail the relevance of the class-B crossover irregularities on the power supply rails of the class-A output stage.
The crossover irregularities are attenuated at the speaker output dramatically and the tracking rails actually improve the linearity of the class-A output stage by effectively bootstrapping Vce. In my design, any minescule remnants of crossover distortion will be cast completely into oblivion by Hawksford Error Correction applied to each class-A output stage. And I'm also using heaps of global negative feedback.
Leolabs said:
Oh, there are lots of transformers and lots seperate rail supplies. I'll go through all this in the future with the circuit details.
Cloth Ears said:
About $780 + GST and freight.
Cheers,
Glen
Hi Glen,
Man, if you plan a 1024W amp for home use, you must have at least a 10,000 watter in that V8 VK Commodore... 😉
Cheers
Stuey
Man, if you plan a 1024W amp for home use, you must have at least a 10,000 watter in that V8 VK Commodore... 😉
Cheers
Stuey
- Status
- Not open for further replies.