Lot of requests for this one after I posted the Stingray pre a few weeks ago, so here's the Sabre II. Pretty similar the the Stingray but with a few value differences and extra resistor in the feedback loop, and the added bright switch.
I´ve seen that it is like a single OpAmp (LM741, TL071 and so meny others) but, it is a PROGRAMMABLE OpAmp. The Datasheet says that the "Programmable" thing is because "A single external master bias current setting resistor programs the input bias current, input offset current, quiescent power consumption, slew rate, input noise, and the gain-bandwidth product".
I guess that´s just for having the minimum power consumption. The Resistor that "programs" the OpAmp is the 1M5 one in Pin 8, wich in common OpAmps has no connection. so, I just guess that in using a 741, 071 or whatever, everything should be the same, exept for that resistor in Pin 8, wich should not be.
Check out the support documents from your pickup's manufacture. They should have some sort of wiring diagram. And whatever wire from the pickup goes to the volume pot (to one of the lugs, not the ground wires to the back of the pot) will go to the input of the preamp circuit board
Hi! I tried this circuit without luck (2 months ago) and Stingray with more luck (2 of my basses have ir now. After that, I started to layout some preamps for my basses and some pedals, and I uploaded this one based in your way of drawing layouts. https://selftaughtcreativity.wordpress.com/2021/07/06/sr-480-bass-preamp-pcb-layout/. I hope you like it, feel free to share if you like or tell me if you need something. I'll try to post some more layouts, AMPEG SVT Bajaman, Stingray 3EQ, etc...
thanks for this awesome layout.. kudos.. 😄
ReplyDeleteWhat replacement do you recommend for the LM4250?
ReplyDeleteI´ve seen that it is like a single OpAmp (LM741, TL071 and so meny others) but, it is a PROGRAMMABLE OpAmp. The Datasheet says that the "Programmable" thing is because "A single external
Deletemaster bias current setting resistor programs the input bias
current, input offset current, quiescent power consumption,
slew rate, input noise, and the gain-bandwidth product".
I guess that´s just for having the minimum power consumption. The Resistor that "programs" the OpAmp is the 1M5 one in Pin 8, wich in common OpAmps has no connection.
Deleteso, I just guess that in using a 741, 071 or whatever, everything should be the same, exept for that resistor in Pin 8, wich should not be.
With 1.5MΩ on pin 8, the op amp has a GBW of 180KHz, slew rate of 0.1V/µs, and quiescent current of about 30µA. There are lots of op amps that meet these specs. However, it's nearly impossible nowadays to find them in the nearly-obsolete DIP-8 package. I did a search across many manufacturers and only found one op amp that is still produced and has similar specs to a LM4250 with a 1.5M programming resistor to ground at a 9V supply.
DeleteThis op amp is the LT1636CN, from Analog Devices. It has slightly higher power consumption (45µA vs 30µA) but otherwise should be pretty similar.
I use LT1354 and run it at 18v
Deletehow do i use it onboard?
ReplyDeletePositive wire from the pickup goes to the In pad, Out pad goes to the jack.
ReplyDeletemy pickup is a mmpro cabrera, so it has 4 wires ... what would be their positive?
DeleteGoogle’s your friend there. Not familiar with that pickup
Deleteno friend, I'm not ... I never called pickups in my life ... help me if you can, thanks ...
DeleteCheck out the support documents from your pickup's manufacture. They should have some sort of wiring diagram. And whatever wire from the pickup goes to the volume pot (to one of the lugs, not the ground wires to the back of the pot) will go to the input of the preamp circuit board
Deleteinput cap is 1uF and output is 10uF
ReplyDeletedo your have a sound or video demo for this pedal?
ReplyDeleteHi! I tried this circuit without luck (2 months ago) and Stingray with more luck (2 of my basses have ir now. After that, I started to layout some preamps for my basses and some pedals, and I uploaded this one based in your way of drawing layouts. https://selftaughtcreativity.wordpress.com/2021/07/06/sr-480-bass-preamp-pcb-layout/.
ReplyDeleteI hope you like it, feel free to share if you like or tell me if you need something. I'll try to post some more layouts, AMPEG SVT Bajaman, Stingray 3EQ, etc...
Este capacitor amarelo e de cerâmica ou tantalo ???
ReplyDeleteThis comment has been removed by the author.
ReplyDelete