Wow!
Cool Actually - as an option - 1W resistors can be SMD 2512 under the board - small, easy to solder, good heat dissipation... still single-sided
This thought flew through my mind at some point, but I decided to pretend it's no problem Never had any damages though...
Ah! One more thing. Let's put a couple of additional connectors, so that one can drop 6.8k 1W resistors and zeners, and connect the IPS section to standalone +/-15V regulated power supply. For "hi-end" builds
Never had any damages though...Ah! One more thing. Let's put a couple of additional connectors, so that one can drop 6.8k 1W resistors and zeners, and connect the IPS section to standalone +/-15V regulated power supply. For "hi-end" builds
yes - low voltage and rather low current...
(1.8V - 0.65V) * 5.35 mA = 6 mW per resistor
I've never seen those 2N5089's before. Are they a big advantage over the BC5xx?
high gain and low noise at the same time... yes, even better noise characteristic than BC5xx
Hi Marc - cool version. One thing - middle (moving) and bottom pins of TR5 pot should be connected.
Variation with MOSFET as a VAS core
Just tried an interesting option with IRF9610 as a VAS core.
Around 10db higher loop gain, a bit sharper square wave response.
Although - very close to the original version.
It can be built on the same PCB - just the FET needs to be flipped over:
BJT pinout is ECB;
FET pinout is GDS - after flipping over it will be SDG - just what we need.
I have also added an optional C9 (1pF) cap from the VAS output to NFB side input (negative) - it would be good to add it to the PCB for either option.
All the values, different from the original design, are shown in RED. Sorry for an accidental RefDes "renumbering" - this illustration is just to show a few value differences.
Keeping in mind overall simplicity of the design, it would be interesting to see if somebody will notice some audible difference between those BJT/FET VAS options in a proper A/B test
Just tried an interesting option with IRF9610 as a VAS core.
Around 10db higher loop gain, a bit sharper square wave response.
Although - very close to the original version.
It can be built on the same PCB - just the FET needs to be flipped over:
BJT pinout is ECB;
FET pinout is GDS - after flipping over it will be SDG - just what we need.
I have also added an optional C9 (1pF) cap from the VAS output to NFB side input (negative) - it would be good to add it to the PCB for either option.
All the values, different from the original design, are shown in RED. Sorry for an accidental RefDes "renumbering" - this illustration is just to show a few value differences.
Keeping in mind overall simplicity of the design, it would be interesting to see if somebody will notice some audible difference between those BJT/FET VAS options in a proper A/B test
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