passive guitar mid cut?

[daz]

Far as i knew, theres no way to do this without an inductor. Someone is telling me however that this will do it. I can't see how but please enlighten me if i'm wrong and if there is really a way to cut mids without an inductor. And no, i'm not talking about cutting lows and highs to create a mid boost. I'm talking mid CUT.

[Fluoroscope 5000]

That's a mod for a 5e3 amp circuit: https://robrobinette.com/5e3_Modific...us_Mid_Control

Someone misunderstood how it is implemented.

[daz]

That's a mod for a 5e3 amp circuit: https://robrobinette.com/5e3_Modific...us_Mid_Control

Someone misunderstood how it is implemented.

Yeah, thats basically what i thought but he's saying he implemented it in a guitar and it cuts mids at about 450z. I coudn't figure out how he could say that unless his ears are not great to put it nicely. In any case, unless someone can tell me i'm wrong i have to assume theres no way to do a passive mid cut without a inductor. And that being the case if it is, anyone got a link to a schematic for one that will work well in a LP special with p90s to cut out some of the nasal tone from those pickups? Don't want different pickups, as i like them. I just want that option at times.

[Chuck H]

Without the consideration of "ears"...

This circuit is just not suited to the particulars of a guitar circuit without more considerations. For starters you would change the unadulterated tone of the instrument too greatly to make it worth while. You can see that the resonant peak is diminished considerably by having this wired up. Green is a stock circuit for parallel single coils and purple is with the "mid cut" circuit in place and set to full off on the control.

[Chuck H]

In use it doesn't fare much better. Below is with the control set to half the pots resistance (purple) and then fully cut (green). You can see that at half resistance the signal is cut by a whopping 8dB with almost no actual effect from the control other than squelching the resonant peak off the signal. At full "cut" the signal level at frequencies that should not be part of the control are cut by a huge 12dB with a mid cut of about 10dB relative to the other frequencies. So ther IS a mid cut at full down on the control. But there's also a significant affect to the signal level overall and even with the control set full off.

I don't like this idea at all.

[Chuck H]

OTOH... Even the more popular mid cut control that uses an inductor doesn't really do anything good until the control is all the way down. Trying to get subtle levels of mid cut are virtually impossible. The control is basically a very long throw on/off switch. Since the goal of mid cut tone circuits is usually to clean up the guitars tone maybe a signal reduction would be ok.?. But I'd still hard wire it on a switch rather try to use a control pot. Because the control offers no useful control.

[daz]

I figured he was likely experiencing some form of placebo effect, but the last post about inductor based ones has me thinking i'll just pass. Guess this is why u don't see many people talking about them.

[Chuck H]

I used one for a while. It was actual a handy tonal variation for gigs to get cleaner tones from a distorted amp without having to stomp on pedals all the time. But like I mentioned, there's no subtlety in the control. The only useful positions were all the way on or all the way off. I think you could get the gain and mid cut simultaneously with the Framus circuit just switched in or out. No control pot. Maybe on a push/pull pot on the tone control. In fact if you play at a typical gain level most of the time you could adjust the circuit values for the amount of gain reduction along with the mid cut when the switch is thrown. You would be able to go from dirty to cleaner just by pulling the pot.

[daz]

Looks to me like u get the mid cut but theres a top end boost too which i absolutely don't want. Especially considering the mid cut itself will accentuate the top even without that boost, so it would be overkill on the high end.

[Chuck H]

Well something can always be designed that would work better for a guitar. Even without an inductor. If you're interested.

Would you want this to be the only tone control or would you also want a standard tone control?

[daz]

Thanks, but thats ok. I don't think it's that important and u know what a fiasco it is when i try and do something that's not cut and dried. I'll just leave it as it.

[Fluoroscope 5000]

Not sure what other mid cut circuits perform like, but myself and a slew of others use the ~$40 Wilde "Q-filter" for a variable mid cut with the low slope point of the mid cut being determined by the cap value in series with the inductor. A 5~10k resistor is also suggested to limit the peaks when it's all the way down as well as reduce the bass slightly, but it's not a necessary part of the network. The impedance of the inductor is only in the 100's of ohms even though it's 1.8H, which helps with the high end. There are many p0ints along the pot sweep I find useful with my configuration. I also have a master tone knob on said guitar, and there is an audible difference between setting the tone knob vs the Q-filter down just a few notches, but it doesn't start dipping strongly until below ~5 on the knob.

A P90 would be limited in the output of the upper peak freq, since they are relatively high impedance pickups, but it might be worth a try. Not sure what you consider the nasal part of the spectrum, but I'd configure it to dip in the 1~1.5kHz range to start. You'd then get an upper peak freq anywhere from 2~7kHz depending on where the knob is set and your cable capacitance, which should be very useful. That would require a ~3nF cap (assuming ~7H for the P90), and you might need to try a few different values to get it right where you want it. I'd think raising the lower peak freq above 1kHz would make it more nasally, but you can wrap smaller value caps over the first one to lower the lower peak freq. You can order caps and resistors really cheap from BYOC. Ceramic and polyfilm are fine. Get the polyfilm if you can. Don't waste money on esoteric caps or resistors that make no tonal difference in a guitar, and may even leak or drift.