Those graphs don't quite actually show that though, since they are models of his buffer-added circuit, not the original. I agree that the original circuit sounds pretty nice though, especially with the pickups it was intended for.
I'm tweaking the design and used a 100K input resistor instead of the 220K. I noticed the treble pot behaved a lot differently. Does the 220K resistor along with the 1n8 cap form some sort of high pass filter to treble pot? So using a lower value resistor causes less treble to go through to the pot?
What are you trying to accomplish?
Changing the 220K to 100K changes overall gain, and also boosts bass relative to treble quite a bit. That will definitely impact how you hear the treble control response.
thanks for the info. I was curious about the behavior of the treble with a lower resistor. I'm building these in enclosures and the original design sounded too tame. after lower the input to 100K and increasing feedback to 220K it sounds a lot better. I use the LT1351's in the builds. I build various outboard preamps with jfets and opamps and I'm surprised at how warm and musical the Stingray sounds in comparison.
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Try changing the 1M rev audio pot to 500K rev audio. Much easier to find, and will boost the treble a little to boot. I used LT1351 in mine too (love free samples), and settled on 180K for the feedback resistor, but staying with 220K for the input one. I also have my own board layout done, but haven't gotten around to getting any fabbed yet.
Tayda is carrying those C1M pots now and they are only $0.50. 1M OHM C1M 1MC Anti-Log Taper Potentiometer I already bought a crapload of them. I get the LT1351's directly from their website at $3 each. I noticed the 100K input resistor increases the bass and the sound is more crisp and clear.
Thanks Paul, I'll file that away in case I get an application it'll work in. Won't fit in my bass, but like you I'm already happy enough with what I have.;^}
I played the bass through a PA system and the sound is thunderous. The mids seem to be a little less scooped while keeping that Stingray sound. those resistor changes make a huge impact on the sound. I also did the same changes to the Sabre preamps. increbidle how a $100 OLP bass with a $10 (in parts) preamp can sound 
I got some more from samples from Linear Tech. The LT1363 is way over the top as far as treble. The highs are crystal clear but there are some mids that are being scooped. sounds like this chip would work well in a different design. The LT1354 sounds great in both Sabre and Stingray preamps. The high mids are more pronounced than the LT1351. It has a more aggresive sound than the warmer LT1351. wish I had an O'scope so I can see whats going on. Its fun to audition chips and hear different tones
Interesting. I'll try to swap in an LT1351 for the LM4250 in my model, which I got from PassInWind. The plot below is using the LM4250 with many component values substituted for lower noise, using buffered pickups. I set it up so that with the treble and bass pots at 0.4 it's virtually flat, but you can see the roll-off of highs, which I assume is from the very low slew rate of this chip. So in theory with a faster chip (that also requires more current) we'll see the highs continue flat for longer. Good experiment.
I have to say that although I haven't finished building my experimental preamp I think I'm going to like that roll-off. What is there at 13K that I want to come out of my rig? String squeak? Maybe if I learn to slap better I'll want super bright. But then again my MB115 couldn't reproduce those highs anyway; I'd have to swap up to a cabinet with a tweeter.
I have to say that although I haven't finished building my experimental preamp I think I'm going to like that roll-off. What is there at 13K that I want to come out of my rig? String squeak? Maybe if I learn to slap better I'll want super bright. But then again my MB115 couldn't reproduce those highs anyway; I'd have to swap up to a cabinet with a tweeter.
An externally hosted image should be here but it was not working when we last tested it.
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