Single Ended CFA

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#62
bogdan_borko said:
On the bottom layer of my proto pcb, under the one electrolytic, you could see layout for 1206 10uF cap for bypass, is this a bad idea or not? These caps are cheap..
Click to expand...

depends on the cap, usually you want to avoid piezoelectric ceramics (multi layer npo is good),

I like to have my boards clean after soldering, washing off the flux with acetone (regular lead solder).
 
#64
Prasi, ok, I'll send finall values leter, I hope there will be no changes in the schematic, maybe something minor about compensation I still have some experiments to try..
Thanks Bigun, yes I'll clean everything after experiments... And yes I've meant multilayer caps.
 
#65
Different transistors for T1: BD140, 2SA1360, KSA1220 8W at 3R9 load, or 16Vpp.
 

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#71
It's connected to speakers again. Sounds very good and there's a subtle but hearable difference in sound even at low levels under 1W. Sound with degeneration resistor and higher 2nd harmonic is more "sweet", while bypassed deg.resistor with lower second harmonic, sounds more "transparent" to me with better bass control.
Now the harder part, the chassis 😀
Btw, Prasi R22 is 100R.
 
#73
Hi Prasi,

Most of the axial lead 2.2uF PP film caps I use are a min. 20mm x 12mm in size.
Maybe add another set of pads spaced 20mm and the leads could be shaped to fit around the cap ends to fit in the 20mm LS. The width shouldn’t be a problem because the one side is free at the edge of the board, the other side has space until the trimpot is reached.
Thank you for considering the request.


Hi Borko,

The “damping factor” switch is a neat feature to incorporate, Cool!
This project could lend itself nicely to use CPU coolers/fan with a higher bias for a very compact amplifier module.

Cheers,
Vunce
 
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#75
Hello Bogdan,
thank you for the updated schematic.
here is updated files and gerbers.

To Vunce,
now i have there 22.86mm pitch x 9mm cap. so plenty of options of either PP or polyester caps (15mm pitch and 10mm pitch too).
i have also copied some traces on top, so if someone wants to manufacture pcbs, they get nice masks and pads on both sides.

regards
Prasi
 

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#78
When I was doing single sided boards with power transistors on the bottom side, I found it useful to use eyelets on the power device leads so that I could adjust the device spacing, and then solder the power devices in place from the top side. It saves some headaches. Also, many manufacturers use eylets for snap-in and other large caps so you get extra retention from the solder fillet.
 
#79
bogdan_borko said:
Great Prasi thanks a lot! R15 is also 2W resistor.
I'm assembling another channel to hear it finally in stereo 🙂.
It's a slow, but enjoyable process..
Click to expand...

Thanks Bogdan,
Yes a 2w can be fit there , so also BPR 56 type 5W also for R16/R17.

To Vunce,
The Gerbers posted earlier had some silk screen issues (part values were also included creating text overlap). here are correct gerbers. Also posting other files for convenience.
 

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#80
wrenchone said:
When I was doing single sided boards with power transistors on the bottom side, I found it useful to use eyelets on the power device leads so that I could adjust the device spacing, and then solder the power devices in place from the top side. It saves some headaches. Also, many manufacturers use eylets for snap-in and other large caps so you get extra retention from the solder fillet.
Click to expand...

Thanks wrenchone, practical idea, what kind of eyelets, never seen it on a pcb, any photos?
 
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