Sure, we can replace most old or unsuited transistor types with modern, better suited and higher performance types. Unfortunately, that can also lead to a loss of the original, often preferred, subjective sound quality. It is a common mistake to assume that upgrades /updates should always be based on improved specs and measurements rather than actual listening qualities that will best satisfy the buying customers.
I'm thinking here of examples of Linn and Naim brand amplifiers which persisted with these ZTX semis as VAS pairs for decades and for somewhat obvious reasons. While other semis have been routinely updated with new models and upgrades, these Zetex/Diodes Inc. types and similar, remained in place because the harmonic distortion pattern produced by them in the circuit, is or was a desirable, characteristic part of either brand's sound quality.
After all, we buy a clone or clone kit, based on the reputation of the original product, not an arbitrarily updated design that most likely will sound nothing like it. That's why we will be wasting our time assembling most clone kits, however well they may perform.
I'm thinking here of examples of Linn and Naim brand amplifiers which persisted with these ZTX semis as VAS pairs for decades and for somewhat obvious reasons. While other semis have been routinely updated with new models and upgrades, these Zetex/Diodes Inc. types and similar, remained in place because the harmonic distortion pattern produced by them in the circuit, is or was a desirable, characteristic part of either brand's sound quality.
After all, we buy a clone or clone kit, based on the reputation of the original product, not an arbitrarily updated design that most likely will sound nothing like it. That's why we will be wasting our time assembling most clone kits, however well they may perform.
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tolerable. But the performance I designed and measured is not good.
So I gave up using it. So I don't recommend you to use my PCB.
If there is a problem, it is not good.