Based on Hugh Dean's AKSA 55

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#941
Yes, that's what I was suggesting. Only I would not use 100R for the emitter degeneration - I think it's too high and although it nicely smooths out the gain curve of the LTP it robs it of too much gain when used with a simple single transistor voltage amplifier following it. I think in my build I used 10R max but I may have experimented with 4R7 too. Just enough to buy you a little tolerance on the LTP behaviour but still retaining good gain.
I don't want to hijack your post but I would refer you to the schematic I posted here: https://www.diyaudio.com/community/threads/tgm-amplifier.140461/page-18#post-3259963

The value of the capacitor in question is best chosen by ear because it's so instructive to hear the differences and get a feel for the design. Anyhow, with the transistor I used and the layout I used I found that a value around 47pF would be a good starting point. I found that 15pF was too small (sound was not quite right, a little bright or something) and 100pF is too big (sound loses it's magic whatever that means).

In your schematic, I would advise using high quality electrolytic (e.g. Nichicon MUSE or whatever they call their hi end audio range these days) for C4 and C13. The capacitor that filters the power to the LTP (C13) can be interesting to try different values. The bootstrap cap, C4, can be increased to 220uF if a high quality cap is on-hand as it supports lower frequencies better.

The input cap, C6, is usually a high quality film type and needs good space for the higher quality ones. However, many years later I discovered that I got great sound from using a Nichicon Bi-Polar (audio grade) capacitor of around 10uF but this does change the time constant at the input.

It's a great amp to DIY.
 
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#943
Hi,
now the AKSA has two emitter resistors. That was no nice work because I dont wanted to change the size of the pcb. Moved a few componets and now it is finished.
@Bigun thanks for your advices.
I think nobody had tried to make a layout from the BIMO schematic until yet...
For the little pf capacitors i always use glimmer CY22-2. For nf i use wima capacitors RM5. Electrolyt muses are very good and i use if i can get with the right diameter.
In the AKSA amp R23/R24 R12/13 R15/R16 the resistors should be 0,1 % or measuring out for identical value....
I uploaded new gerber files with emitter resistors.

It was only a favor to make this pcb, dont know if i ever built one. I have too much own projects..

Greets
Peter

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#946
Hey Chris, there's nothing 'mandatory' about circuit elements but you are right that a CCS is best practice for reducing distortion. However, the resistive long tail for the LTP along with other circuit elements are key to the sound of this amplifier (read my TGM thread, I think there's more in there). If you want to go all-out in terms of best practices then I would offer this: https://www.diyaudio.com/community/...-by-rod-elliot-p3a.245619/page-32#post3785052
 
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#948
Bigun said:
Hey Chris, there's nothing 'mandatory' about circuit elements but you are right that a CCS is best practice for reducing distortion. However, the resistive long tail for the LTP along with other circuit elements are key to the sound of this amplifier (read my TGM thread, I think there's more in there). If you want to go all-out in terms of best practices then I would offer this: https://www.diyaudio.com/community/...-by-rod-elliot-p3a.245619/page-32#post3785052
Click to expand...
Nice thread...i read not all

is there a advantage of useing at TGM8 the rail caps directly at the PCB?
jpk73 build a huge PCB with protection and fat "snap in" caps.

kr
chris
 
#951
Hi,
a small favor becomes a big one...🙂
i can try anything, but there is not much space on this board. Tell me what you want and i try...MrHifitunes asked for a small board under 100 and 60 mm.
If the pcb size does not matter i can change the height if necessary. With a small board its possible to save money....

Peter
 
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#952

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#953
Looks very nice that amp board.
I am willing to help and to learn....i can use a schematic to make a layout for a pcb, but i cant design an amp by my self. If i ever will learn enough to do, dont know...
I learned a lot in this 1 year i am active here in this forum, but i have only a little knowledge in electronic. So, please be patient with me....
I recognize the knowledge that is present here, sometimes I am overwhelmed...😉

The AKSA amp is very interesting, but i don't understand everything in detail. I hope MrHifitunes will built the amp with my pcb and report how it sounds.
Exciting...

Greets
Peter
 
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#956
Think so too, only Bimo can answer the question. It is not the only schematic he did so. If you have a look to other schematics he made, you will find this jumpers too. At a first look i thought it has only to do with the bias transistor, but there are other components following.

Greets
Peter
 
#958
chermann said:
Nice thread...i read not all

is there a advantage of useing at TGM8 the rail caps directly at the PCB?
jpk73 build a huge PCB with protection and fat "snap in" caps.

kr
chris
Click to expand...
Peter can try it. Then it is a full amp board. Proection + bridge and caps. CRC?

I ordered the "Standard" board and will try it with an SMPS. If it is good, I have could have a go at the "full" board ".

2 types maybe ???
  • power transistors on one side type
  • power transistors on both sides but keeping the board long and slim in size. eg 180mmX55mm.
 
#960
To switch from "side" transistors to "in one line" transistors is not difficult. I think for heat release the transistors on the pcb side is the better choice...
What SMPS will you use ? Mostly i use SMPS from Connex Electronics.

Greets
Peter
 
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