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DIY Stompboxes => Building your own stompbox => Topic started by: mark2 on December 19, 2020, 05:06:40 PM

Title: Choosing replacement darlingtons for Scrambler
Post by: mark2 on December 19, 2020, 05:06:40 PM
The Ampeg Scrambler used 2N5306 which aren't practical for me to get.  A lot of people report having good luck with BC517, and some reports of MPSA14.

Are there any specs to be concerned with when picking a replacement other than hfe? I ask because I'm trying to choose some SMD transistors that'll work well with this circuit, and not sure what else to look at.

I was considering the MMBTA14LT1G (https://www.mouser.com/datasheet/2/308/MMBTA13LT1_D-1811759.pdf) since it seems to the equivalent of the MPSA14.  But wondering if the MMBT6427LT1G (https://www.mouser.com/datasheet/2/308/MMBT6427LT1_D-1811821.pdf) might behave more like the BC517 that everyone loves.

Any tips other than to just try them and see how they sound? Thanks!

(https://i.imgur.com/cKAhCiD.png)
Title: Re: Choosing replacement darlingtons for Scrambler
Post by: iainpunk on December 19, 2020, 05:32:52 PM
for this specific fuzz, the transistors aren't too critical, most darlingtons work, even just cobbled together ones made from 2 normals. you can also look in to sziklai pairs if you are going to cobble them. (negligible difference in sound, a tad more linear at high gains)

also, D4 and D5 aren't actually put on the board in 95% of original units

cheers, Iain
Title: Re: Choosing replacement darlingtons for Scrambler
Post by: mozz on December 19, 2020, 07:50:43 PM
 I have some old 70's darlington pulls here in the TO-98 package, i can measure gains if you want some.
Title: Re: Choosing replacement darlingtons for Scrambler
Post by: mark2 on December 20, 2020, 01:29:23 AM
Quote from: iainpunk on December 19, 2020, 05:32:52 PM
for this specific fuzz, the transistors aren't too critical, most darlingtons work,

Thanks, I won't worry too much about it. I'm going to try the MMBTA14 to start with.