Any experience/comments for the AMZ Pickup Simulator ?

[chptunes]

http://www.muzique.com/lab/pickups.htm

Will it match an Active Jazz Bass to a Bazz Fuss?

Comments appreciated..

-Corey

[JFace]

No experience with that passive network but I can vouch for the concept. Resonant upper mids can make for a tasty bass tone, and really aggressive sound distortion and fuzz. I would try for an active way to achieve that result, though. Inductors can potentially be very noisy.

[digi2t]

I found it very helpful where impedance sensitive effects are concerned, my Parallel Universe II for example. The oscillation function worked fine with the guitar signal straight into it, but once I placed it into a signal chain with several buffers along the way, the pedal would not oscillate anymore. Since it likes to see a guitar pickup at the input, I build the simulator into the front end, and all is well now. No matter where in a chain I place it, it works fine now.

[lungdart]

That's a +2 on active implementation of this simulator

Transformers are costly, noisy, are heavy and vibrate. It could be more practical to combine a tuned bandpass filter, some mixing, followed by a low pass filter on the front end post buffer.

[Davelectro]

Couldn't this be simulated by means of an opamp-based resonant filter?

[chptunes]

Thanks for the input.. glad there's some good experiences.

I'd like to use Battery power, so I want to keep the milliamps down.. Passive components are appealing.

Maybe I'll give this a go.. Bazz Fuss with Mix control...


how do you print screen

[JFace]

If you use the OPA2277 (dual) or OPA4277 (quad) op amp your current draw will be microscopic (literally). I've built a state variable filter with the 4277 with great results. It can give you exactly the tone profile that the inductor would give, and sound a lot cleaner/no noise. Check out the Alembic Like Filter schematic (google it).

[chptunes]

If you use the OPA2277 (dual) or OPA4277 (quad) op amp your current draw will be microscopic (literally). I've built a state variable filter with the 4277 with great results. It can give you exactly the tone profile that the inductor would give, and sound a lot cleaner/no noise. Check out the Alembic Like Filter schematic (google it).

Found the schematic.. thanks for the advice.  Since I have the passive components in my bins, I'll see how it works first.. all the while, keeping the OPA4277 State Variable Filter on the radar.

I was hoping to keep things simple [and use what I have in stock].

[slacker]

I think you guys suggesting active filters are missing the point of the pickup simulator
It's not just about providing a resonant peak the main purpose is to provide something with a similar impedance,  inductance and capacitance to that of a passive guitar plugged straight into the effect.
The idea being that you can run something like a Fuzz Face after an active pedal and have it sound more like it's plugged straight into your guitar.

[JFace]

Whether you load the next stage or provide the equivalent eq, I think the audible effect would be the same...a resonant high mid frequency with a 2 pole roll-off of the highs after the peak. An added bonus would be that these factors are tunable with active components. I would try both.

[mth5044]

For effects like the Fuzz Face, it isn't going to matter what the EQ is going into it, it's the impedance that causes the desired sound. Place a fuzz face late in the chain, it's not going to matter what the EQ of the signal is, it won't be 'happy'. Place the AMZ device before it and it will set the impedance to what is expected when it's first in the chain, making the play.. 'happy'.

[digi2t]

Thanks for the input.. glad there's some good experiences.

I'd like to use Battery power, so I want to keep the milliamps down.. Passive components are appealing.

Maybe I'll give this a go.. Bazz Fuss with Mix control...


how do you print screen

Another example of it being used, is the Gemini III Dual Fuzz. Search the forum, the schematic is available.

[JFace]

For effects like the Fuzz Face, it isn't going to matter what the EQ is going into it, it's the impedance that causes the desired sound. Place a fuzz face late in the chain, it's not going to matter what the EQ of the signal is, it won't be 'happy'. Place the AMZ device before it and it will set the impedance to what is expected when it's first in the chain, making the play.. 'happy'.

A conventional eq won't do the trick, I agree, but a LPF would produce essentially the same result as the passive network. The passive network that you present as the source to the fuzz face only tampers with the frequency response (this is loading...nothing magic about this term). The only other attribute to consider with such a passive network would be hysteresis effects from the inductor, but that would take quite the signal to realize with a transformer. Take a look at the original article...the basis is one of eq:

The RLC network of the guitar pickup and the connecting cable produces a response that is flat in the lower end of the range but has a peak in the upper mids and rapidly falls off in response at the high end. A simple resistor does not duplicate this response and a more complex circuit may be devised to simulate the guitar pickup.

This eq is unique, and can be realized through the passive network that was presented, or through careful filtering. Or just plug your guitar straight in to the fuzz.

[Gus]

something I posted before green is 10K blue is 100K red is 470k



Also note the above screen shots are at full volume and treble, as you turn down the volume you lose the high end peak. NOTE the volume control is also a tone control.  If you sim this and sweep the volume control you can see this

The AMZ simulator does not have the volume tone change from the guitar volume control

A FF circuit is more of an input summing junction if the first transistor had the gain of a opamp the input would be around 0 ohms.  Look up inverting opamp gain stage
substitute the passive guitar or bass as the input resistor
Part of the first stage gain in a FF is set by the feedback bias resistor 100K 47k etc. / the guitar or bass LRC network

Now think about what happens when you use something with a low output resistance to drive a FF.

[chptunes]

Thanks a bunch guys..

Gus - I just read your post 3 times.. great visual and detail.  You've simulated guitar wiring to a higher detail.. I'm trying to grasp the R5 variable.  Is R5 included as a part of the simulator circuit, or does it simply represent the possible input impedance values of the unknown circuit that follows?

[PRR]

> trying to grasp the R5 variable.

It looks like a standard Guitar Amp input.

If you are feeding one of the antique minimum-parts fuzzes (Gus mentions the FuzzFace), R5 acts like 50K or 5K (I forget how bad a FF sucks). Try 5K at R5 and, with guitar source and guitar pot (R3 R4) way-up, the pickup inductance against this loading makes a *severe* treble-cut. Which is euphonious in a severe distortion, because fuzzing the high overtones makes an angry-gnat haze, while cutting the overtones so mostly fundamentals are distorted is less irritating on the ear and brings out the simple 3/2 3/5 etc fuzz harmonics.

[ashcat_lt]

> trying to grasp the R5 variable.

It looks like a standard Guitar Amp input.

If you are feeding one of the antique minimum-parts fuzzes (Gus mentions the FuzzFace), R5 acts like 50K or 5K (I forget how bad a FF sucks). Try 5K at R5 and, with guitar source and guitar pot (R3 R4) way-up, the pickup inductance against this loading makes a *severe* treble-cut. Which is euphonious in a severe distortion, because fuzzing the high overtones makes an angry-gnat haze, while cutting the overtones so mostly fundamentals are distorted is less irritating on the ear and brings out the simple 3/2 3/5 etc fuzz harmonics.

This is of course true.  The argument in this thread is essentially whether that treble-cut alone is enough, or if there's something special about actually physically connecting the passive pickup directly to the fuzz pedal.  Can you put a buffer before the fuzz and just turn down the tone pot on the guitar?  Can you use an active filter to get the treble cut and have the fuzz respond the same?  I personally think that it will accomplish at least most of the "important stuff", but others contend that the input impedance and/or the inductive nature of the source actually change the way the transistor works somehow beyond the simple treble cut.  I'm pretty sure I've seen RG post something about it too.  Reverse leakage or something something???

[Gus]

The RLC mess of the guitar is the input RLC.
Again look up inverting opamp and how the feedback works