Need a SFT337 with proper hfe for my Vox Tonebender

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Freed
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Need a SFT337 with proper hfe for my Vox Tonebender

Post by Freed »

Picked up this cool early Model 50 with an AC135 in q2 but someone at some point replaced Q1 with a silicon tranny.
It plays ok but way too wooly and a bit noisy.
Looking to swap back in a Ge into V1 and decided the OC76 route seemed the most sexy.
Does anyone have one I could purchase within the proper hfe zone for a Vox Tonebender?
This one also has the 50k pots and ironically also had the resistor across the pot…ha…I pulled that to get a bit more clarity.

Thanks 🙏
Last edited by Freed on Sat Oct 22, 2022 11:21 pm, edited 1 time in total.
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Nick
The Artist Formerly Known As nightraven
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Re: Need a Mullard OC76 with proper hfe for my Vox Tonebender

Post by Nick »

Is this the pedal with serial number #068x? I think if the silicon transistor in that one is non-original, then it would most likely have originally been built with a SFT337 in that position. The OC76 was used a bit later during production of the model 50/v828 than when yours was built, and so it would be a kind of anachronistic. Even then, an OC76 would have been in Q2's position instead.
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Freed
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Re: Need a Mullard OC76 with proper hfe for my Vox Tonebender

Post by Freed »

Thanks for the reply Nick…
Ha yes indeed it is #068x
Ok so given that It would need the SFT337 then?
I’m surprised to hear the OC76 ones came after this, I thought if anything they were before.
So reading from Left to right with the back off the pedal…it should be Q2 then Q1?
Sorry bit of a schematic nube
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Nick
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Re: Need a Mullard OC76 with proper hfe for my Vox Tonebender

Post by Nick »

I think the OC76 was just used for a limited time, but not necessarily from the very beginning. The earliest we've seen so far appear to have already had SFT337 in that position. Yep, Q1 is the furthest part on the right side of the board. Here are pedals #0666 & #0710, for reference:

Image
Image
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Freed
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Re: Need a SFT337 with proper hfe for my Vox Tonebender

Post by Freed »

Ha great!
Mine would slide right in between the two…
Changed the topic title.
Thanks Nick!
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Zuff-1A
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Re: Need a SFT337 with proper hfe for my Vox Tonebender

Post by Zuff-1A »

Serial #0710 was my pedal for many years, sounded very good, when I turned the volume down on the guitar it became clear and bright but kept nice low frequencies. The variants with two SFT-s sounded more hysterical, not as pleasant
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Freed
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Re: Need a SFT337 with proper hfe for my Vox Tonebender

Post by Freed »

Yeah the cleanup on mine is pretty sweet too (good cleanup is essential to my playing) but wide open is just kind of duffs out.
So is the AC135 responsible for the nice cleanup then?
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Zuff-1A
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Re: Need a SFT337 with proper hfe for my Vox Tonebender

Post by Zuff-1A »

I think the AC 135 gives more low end and balances out the bright SFT337
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