I've got guitar amps with 1M impedance. But I need to split the signal to my mixer so I'm using 1M impedance FET DI box. That makes it 500ohm load on my guitar in total and I can hear the slight top end roll off and loosing some sound is annoying.
Is there anything I can do increase the DI box to at least 3M, perhaps modify it?
Another idea I had was to modify stand alone tube preamp by replacing input 1M resistor with 5M resistor and just run the output from cathode via cap to mixer. I'm just not sure what implications 5M on input would have if any.
I don't know how else I could achieve very high impedance signal splitting so I don't get any signal loss.
Thanks in advance for any advice
Is there anything I can do increase the DI box to at least 3M, perhaps modify it?
Another idea I had was to modify stand alone tube preamp by replacing input 1M resistor with 5M resistor and just run the output from cathode via cap to mixer. I'm just not sure what implications 5M on input would have if any.
I don't know how else I could achieve very high impedance signal splitting so I don't get any signal loss.
Thanks in advance for any advice
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You may be better off modding your active FET DI box, by splitting the signal after it goes through the 1M input buffer..does your DI box have an audio transformer at it's output?
What type DI are you using?
What type DI are you using?
Sound difference between 500k and 1 M load is practically undetectable.
Instead, I very much suspect added shielded cable is addi9ng at least a couple 100pF (if not more) to your current setup.
And that you will definitely hear.
As suggested, if you go from guitar to DI box only, with a single cable, and split it there, one (low impedance) jack out to your amp, one low impedance out to mixer, then you will get full range sound.
And having DI box at your feet is way better than putting it on or near your amp.
What guitar are you using? (Singles-Humbuckers).
Do you use pedals?
Because most any pedal, unless vintageish, will have a built-in buffer and avoid the problem.
The DI box I made. It is FET, with Y split, one channel is straight through, the other is tapped by the FET. No transformer. I don't know of any transformer that would have say 5meg on input, is there such thing? That would allow me to use the trafo alone without having to run through FET to the mixer.
I don't think using my DI box would cause capacitance problems since the signal is tapped straight from the source. But I could be wrong. It's not a huge tonal difference, I can hear it mainly when I use single ended amps since those can be brighter. But since I mostly play on the edge of break up, it does affect some of the sparkle in tone. With clean or more distorted signal it's not obvious. I would say it mostly affects my sweet spot.
I don't think using my DI box would cause capacitance problems since the signal is tapped straight from the source. But I could be wrong. It's not a huge tonal difference, I can hear it mainly when I use single ended amps since those can be brighter. But since I mostly play on the edge of break up, it does affect some of the sparkle in tone. With clean or more distorted signal it's not obvious. I would say it mostly affects my sweet spot.
So you have 2 cables unbuffered with the DI box, 1 cable without. You have to realize the pickup is charging up the capacitance of two cables, plus the capacitance of the fet gate. Are the two cables twice the length you would use without the DI box? 3 times?
Twisted pair is about 25 pf per foot. 6' cable to local floor guitar amp is 150 pf. A 6' cable to DI box is 150 pf, a 12' cable unbuffered from DI box to PA mixer is 300 pf. A 2n7000 fet has 60 pf gate capacitance. A IRF610 nfet is worse at 135 pf. Lets assume you used the minimal 2n7000. Parallel load on the guitar pickup is 150 pf + 300 pf +60 pf, or 510 pf. At 20 khz, the limit of hearing, 1/(2*pi*F*C) is 10.9 ohms. that is a pretty hefty load on a 1 meg ohm pickup. Of course not all your signal is at 20 khz, but there goes the highs. Whereas the original 6 ' cable by itself was 37 ohms, 3 and a half times as high.
Best Load on your guitar for a complex setup is one buffer by itself first thing, without any other cables. Like a TL071 op amp like many pedals use for input. Leads to a power supply cord at your feet, but nearly all acts now are using a powered pedal board next to player. If the AC cord is a real nuisance, use an 18 v power tool lithium battery. Split the supply with 2 zeners or 2 regulators for analog ground for the op amp amp + input. At 6 ma op amp load, zeners limited by 22 ohm or higher resistors are the lower current alternative.
BTW congratulations on being able to hear high frequencies. My ears still go to 14 khz, but most of my male friends can't hear even that. Only women friends can hear the difference between a piano that sparkles, like a Baldwin Acrosonic, versus a popular but dull Yamaha console (Yamaha 9' grands are fine).
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Formula looks right but result is surely wrong. 510pFd @ 20,0000Hz, I get 15,611 Ohms. Not only spilled decimals, but I think a √2 factor got in.
Here are some values, I guess the capacity is pF and L in mH tho.
Guitar Impedance Matching - Ironstone Electric Guitar Pickups
Guitar Impedance Matching - Ironstone Electric Guitar Pickups
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I simulated the pickup with 5M input resistance
grey is 500K, blue 5M
Jo you are right it is the capacitance that changes the sound, not the resistance.
grey is 500K, blue 5M
Jo you are right it is the capacitance that changes the sound, not the resistance.
The 1H-10H inductance, against the total capacitance (more than you would think) sets a top-ring and steep fall-off,
That Ironstone page has multiple errors. I strongly suggest you measure it yourself.
That Ironstone page has multiple errors. I strongly suggest you measure it yourself.