I'd prefer two pairs of output devices for 4 ohms, these laterals tend to be a bit short on max current compared to vertical mosfets and bipolars.
Hi Lazy,
Why do you publish so stuff as i TSSA is not finish
It's lefting pot to adjust offset
Marc
Why do you publish so stuff as i TSSA is not finish
It's lefting pot to adjust offset
Marc
Lazy Cat, can u pls provide scope snap shot of this amplifier in action? What is its slew rate? Stable with speaker reactance at high frequency. Or this design only suitable for sub application? Very clear feedback scheme, i have never seen before.
You can use ALF16N20W/ ALF16P20W, just need to check if they can be correctly driven by 2SC/2SA
Marc
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Hi Lazy,
Why do you publish so stuff as i TSSA is not finish
It's lefting pot to adjust offset
Marc
Your delay at TSSA finishing was the reason I had too much time to play around hahaha 😀
No, 1k trimpot is for output bias, two 15k resistors are for input/VAS bias plus DC offset setting. 😉
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Well for those folks who like to simulate here's my contribution so far to the Lazy Cat VSSA, a file to play with.... 😀
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For only one pair and for a thermal stability they're not necessary, laterals have drain current negative tempco so thermal runaway cannot happen. Source resistors as local feedback for distortion reduction you can add them of course, but it will be at best only few dB of THD reduction. 🙄
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yes, it looks very nice !
The Simplified thread started off with something simple like this and then wandered off to something not at all simple. Let's keep this one simple 😀
for temp stability the drain current through laterals must be above some threshold, I think it's 100mA, depending on which FET.
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OK deal, I won't mess with more parts on this one (values optimization only) I promise hehe, although it can be rocketed to complex version in any time 😀
Yes, normally Id should be 100 mA or more, sweetspotted too I suppose.
I setup the circuit from your diagram.
The DC-offset is very small, 12 mV.
The first thing I noticed is that circuit needs some compensation to be stable.
This was fixed with one 22pF from base to collector of KSA1381 and likewise 22pF around KSC3503.
The THD distortion at 1 Watt is remarkably low for such a simple amplifier:
THD 0.0002% at 1 Watt RMS.
Very nice amplifier 🙂
This what I've got with Bigun file.This is at quite low level, at higher level it is much worse.
dado
