Lehle - Sunday Driver  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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kusi
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Post by kusi »

hello my friends,

long time no see, i hope everyone is still alive and doing great? :D

i just spent some minutes tracing the lehle sunday driver, a great sounding buffer / booster which i use in the studio all the time to track guitar di's (instead of the interface/preamp hi-z in).
nothing too special. the power-supply is a bit strange, it's not the best idea to power a 9v linear regulator with 7,5V imho. also the bias-offset of 0,125V, not sure if it's really worth the effort.

let me know what you think!

cheers,
kusi
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Post by zoetrop »

Thanks, I really like your schematic and thanks for your effort! could you please double-check R4, in the photo it looks like 4k7 instead of 47k (which would lead to a ~ 1.58 V bias)?

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kusi
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Post by kusi »

thanks! r4 is 47k, voltage of 0,125V is measured. someone posted the schematic of Lehles paralell pedal here, the small bias-offset is similar.
viewtopic.php?f=1&t=27364&hilit=lehle

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apollomusicservice
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Post by apollomusicservice »

C2=100n
C6=10u
C12=1n
C13=120p
C14=330p
C15=15p
30-50mA current consumption

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Post by x-tn »

kusi wrote:...the power-supply is a bit strange, it's not the best idea to power a 9v linear regulator with 7,5V imho...
Your schematic says "all voltaged measured with 9Vdc power supply."
It looks like it requires AC power. With AC power you would have higher than 7,5V at the regulator input.

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kusi
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Post by kusi »

x-tn wrote:
kusi wrote:...the power-supply is a bit strange, it's not the best idea to power a 9v linear regulator with 7,5V imho...
Your schematic says "all voltaged measured with 9Vdc power supply."
It looks like it requires AC power. With AC power you would have higher than 7,5V at the regulator input.
of course 9vac would make more sense. but the manual clearly states 9V ac OR DC.


thanks apollomusicservice for the values!

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Post by apollomusicservice »

kusi wrote: thanks apollomusicservice for the values!
No problem, I just checked values on my pedal.

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kusi
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Post by kusi »

updated schematic w. cap-values:
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Post by apollomusicservice »

C15=15p

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kusi
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Post by kusi »

is c15 fitted in your version? because in mine it's not (but it doesent really matter if it's 15pF).

thanks for checking!

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Post by apollomusicservice »

kusi wrote:is c15 fitted in your version? because in mine it's not (but it doesent really matter if it's 15pF).

thanks for checking!

Under the S/D switch.

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Post by Cub »

Quite the power filtering! Almost seems overkill, but that's probably why I'm painting by numbers and the good people at Lehle are designing and building these things to put bread on the table.
Please forgive me if this sounds dumb, but would this filtering be helpful in a Big Muff circuit or an Overdrive / Clean boost to keep the noise down?
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Post by FiveseveN »

would this filtering be helpful in a Big Muff circuit or an Overdrive / Clean boost to keep the noise down?
Discrete designs like the more popular Big Muffs have poorer PSRR than something like this, so sure. But what exactly do you mean by "this filtering"? There's a rectifier, smoothing cap(s) and a regulator. Your PSU should already be regulated, but Lehle might not want to take that chance, and that's what the solution is about: flexibility and protection. You can feed it a wide range of voltages with either polarity or even AC and it will work just fine. Interestingly, the "standard" user case where you'd feed it with a proper 9V DC PSU is not the ideal condition, as the others have mentioned above.
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Post by Cub »

Thank you for your explanation, always eager to learn.
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Post by hasanova »

Here are some gut shots of a Lehle Sunday Driver SW (it says "Sunday Driver L v1.0" on the PCB). The version without an on/off switch is already traced. One more difference: this one has the TS (True Sound) and TB (True Bypass) switching.
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Schermafbeelding 2017-07-30 om 19.36.51.png

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Post by hasanova »

One more pic
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Post by hasanova »

The other side
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Post by hasanova »

With some parts values...
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Sunday Driver SW - parts.png

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Post by blacky »

Did anyone try the build on this schematic yet?

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