Transistor for a Phase 90 Clone

[mickey.bellinello]

Hi to all!

I just finished a Phase 90 clone and it works pretty nice.

With the kit I received a matched quartet of 2n5457 instead of the classic 2n5952.

So, here the question: If I get a matched quartet of 2n5952 do I get some improvement (even small) or nothing change?

Thanks so

[jimilee]

IMHO, no. I've built literally dozens of phasers and I haven't heard any difference at all.


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[aion]

JFETs don't play by the rules of other types of components. The manufacturing process is wildly inexact, so they basically just make a batch of JFETs according to a certain process and then label them with part numbers according to their performance.

So 5952s have a VGS(off) range of -1.3V to -3.5V. Typically for a Phase 90 you want it to be in the -1.5V to -2V range.

5457s have a Vgs(off) range of -0.5V to -6V. This means that the entire range of a 5952 will fit inside the range of a 5457.

This is speaking very roughly since there are some other differences between 5457's and 5952's such as the IDSS range. But when used in the Phase 90 we typically only match based on Vgs(off) so other specs are less of an issue.

Long story short - a quad of 5457s and 5952s with the same Vgs(off) value should behave identically. With JFETs, the part number is a lot less rigid than with other types of components and the actual specs of the individual device are the most important thing.

So generally speaking, a batch of 5457s is less likely to render good matches for the Phase 90 since the ideal P90 spec is on the low end of its range. But, it's definitely possible - and no, in this case 5952's wouldn't necessarily be an upgrade.

[mickey.bellinello]

IMHO, no. I've built literally dozens of phasers and I haven't heard any difference at all.


Sent from my iPhone using Tapatalk

Thanks so for sharing your experience!

JFETs don't play by the rules of other types of components. The manufacturing process is wildly inexact, so they basically just make a batch of JFETs according to a certain process and then label them with part numbers according to their performance.

So 5952s have a VGS(off) range of -1.3V to -3.5V. Typically for a Phase 90 you want it to be in the -1.5V to -2V range.

5457s have a Vgs(off) range of -0.5V to -6V. This means that the entire range of a 5952 will fit inside the range of a 5457.

This is speaking very roughly since there are some other differences between 5457's and 5952's such as the IDSS range. But when used in the Phase 90 we typically only match based on Vgs(off) so other specs are less of an issue.

Long story short - a quad of 5457s and 5952s with the same Vgs(off) value should behave identically. With JFETs, the part number is a lot less rigid than with other types of components and the actual specs of the individual device are the most important thing.

So generally speaking, a batch of 5457s is less likely to render good matches for the Phase 90 since the ideal P90 spec is on the low end of its range. But, it's definitely possible - and no, in this case 5952's wouldn't necessarily be an upgrade.

Thanks so much for the detailed explanation!
The bag that contained the transistor reports:
Id 2,5 mA
Vp 1,3 V
What do you think about it?
Thanks so!

[aion]

That sounds perfect to me - at the low end of the 5457's spec, so not as good for buffers/gain stages but perfect for phasers.

[mickey.bellinello]

That sounds perfect to me - at the low end of the 5457's spec, so not as good for buffers/gain stages but perfect for phasers.

Glad to hear! Just a last thing, in caso is it better to have a high vgg or a low one?
Thanks again and sorry for the several questions.

[aion]

Not too low and not too high. 1-2V is usually where you want it. You can go higher but will need a different zener diode.

[mickey.bellinello]

Not too low and not too high. 1-2V is usually where you want it. You can go higher but will need a different zener diode.

Thanks so much for the precious info! Really!