Most folks would run from the sound of an output transformer saturating.
There's a healthy dose of Internet mythology in this.
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Even when solid state instrument amps were first introduced (pre-Internet), the impression which I kept hearing was that at least for LEAD guitar, that the sound of an output transformer saturating was what gave them the sound and sustain which those players preferred, and to which they had become accustomed.
IIRC, this characteristic was mainly due to even-numbered harmonics being re-enforced when such saturation occurred.
IIRC, GK's first solid state offering for lead players did have an output transformer, and 2 12" speakers somewhat like a Fender Twin, in an effort to emulate and continue that legacy, and that other amps which claimed to achieve pleasing distortion thru various preamp topologies did not gain much traction at the time from lead players.
Bassists were quicker to give solid state a prolonged chance, it seems, and case in point, I during the 70s switched away from an SVT with the proverbial 8x10 cab, over to an Acoustic 371 rig with the single CV 18 speaker, reverse facing in a W-folded horn cab, and it DID save some weight.
While keeping the same instrument, the simultaneous change of cabinet made it hard for me to properly analyze the difference between the two heads, and in those days the s/s amps were mainly Class A/B - at least from Acoustic they were, all the way to the output coupling cap just before the speaker, on a power supply which must have been single rail, I would think.
I did like the Acoustic 370 top enough that I later bought other heads of theirs, such as a 470 (dual footswitchable channel version of the 450, both models of which were really lead guitar heads), and even still own and have used an old Acoustic 150 Bass head as recently as during this past year, for a couple of dozen gigs with a part-time band.
BTW, my first experience of having a graphic EQ inside of a bass head was with those Acoustic tops, and such design, while forward-looking and innovative, was poorly executed. - I discovered that insufficient attention had been paid to the bandwidth (Q) of each band in the then 5-band EQs of these amps, and consequently the bands either were too wide and severely overlapped adjacent bands in some cases, or were too narrow and left huge gaps between bands in other instances, along with a very 'peaky' sounding response when fully boosted. - This oversight I proved by using a signal generator and oscilloscope. - My solution was to tweak the EQ bands by putting padding resistors in parallel with the inductor coils, or changing the values of any which were already there, to change the Q of the filter in question.
I may also have changed the values of some of the capacitors to true up (or deliberately change ?) the centre frequencies of a band or two, but not certain of this, as it was so long ago, and my notes about all of this are hopelessly buried in a folder in a banker box or tote somewhere.
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