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That's your choice. I forgot to mention I did A/B test with both opamps and the LT1351 blew it away there was no comparison. It made the LM4250 sound dead. I also changed the value of some components for more gain and less mid scoop. The pickups are custom wound Alnico V's with extended pole pieces. I was shocked at how great it sounds. It blows away the 1977 Stingray I used to own
As you say, that's your choice. Tone of course we all know is completely subjective. My guess is the LT1351 draws lots more current. Any idea how much more? Did you change the current limiting resistor too? I too prefer the sound of Alnico Vs. Its certainly easy enough to change the response curves. That's pretty much how Leo designed the thing, just kept playing with components until it sounded like he wanted it to.
250uA, so roughly a 1000 hour + lifespan on a 9v battery, depending on how picky you are about end of service voltage (I pull them at 8V at worst). For an even better sounding (IMNSHO) and much less expensive low current modern opamp, try OPA205, which is spec'ed at 240uA nominal. But the LT1351 is a very decent choice if a through-hole format is desired.
Yes, I bought it thinking about to buy pass the preamp and keep using the volume knob. But I don't have so much experience and knowledge to figure out how I should solder it with the preamp. I'll try it and let you know.
Complex switching circuitry tends to drive me crazy, so I take the lazy person's approach and just don't do it. I'm sure there are many ways to skin this particular cat, but the problem is that by the time the signal gets to the volume control, it is a low impedance circuit so the volume control is just 25K. Passive volume controls range, generally speaking, from 250K to 500K, sometimes as high as 1Meg. So a dual concentric control with one value of 25K and the other of at least 10x that would have to be custom made and not cheap, plus you'd have to order a zillion of them. If you can live without a volume control, just install a switch - one position sends the signal directly to the output jack, the other position sends it to the preamp. If you have room, you could also just drill a hole for a passive volume control. I'm not sure if I am helping you or not.
You as everyone has helping me a lot. I've just decided take the path to keep it as simple as possible and just gaveup add it to my bass and kept it as the original one. The only thing Ive just added was the Seymour Duncan smb-4a and my Harley Benton MB-4 is finally complet! Thanks everyone for the support in my small project!
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Yes that's correct!can't edit my post apparently, this helped with the board's notations :
View attachment 7368245
(different layout on the components, but the battery, jack and pots connections seems to be the same
and thank you Boscoe !
Yep that's it. It sucks they are 7 dollars they used to be $2.58. I got 5 free samples from LT before AD bought the company. You can get free samples but they don't accept public email address. They are $3 if you want to buy them https://www.analog.com/en/products/LT1351/sample-buy.html If you install the LT1351 the 1.5M resistor on pin 8 has to be removed
The "real" equivalent to the old LM4250s are the NJM4250, 60 cents each in quantities of 50 or more. If you want a few, I'd be glad to sell you some. PM me if interested. I've been selling my version of the onboard preamp for several years now.
