Triple Wreck - Are 4580s gainer?

[seedlings]

I etched and built the madbean upper decker.  TL072s, JRC4558s, and LM833s don't sound as gainy as the original.  Would 4580 chips take it up to the last notch?  The flavor of the tone is there, but it just doesn't seem to have quite the feedback/gain/oomph as the sound demos.

CHAD

[Mark Hammer]

1) Gain and distortion are linked, but are not the same.  Swapping chips in the circuit does not change the gain.  What it can do is change what the gain results in, though often that depends on how much gain is applied.

2) Looking at the schematic ( http://revolutiondeux.blogspot.ca/2012/01/wampler-triple-wreck.html ), there are several ways in which the application of exactly as much nominal gain as the original might result in a "less gainy" (i.e., less distorted) sound.  First, the diodes used can vary somewhat in their forward voltage, and the clipping threshold produced.  I've had silicon diodes of the same part number with forward voltages below 500mv and nearly 700mv.  The higher the forward voltage of the individual diode, the shorter the portion of the picked note that it might clip (remember, there is an initial peak and then the signal level drops quickly after picking).  With 5 diodes responsible for the clipping, it is easily possible for their cumulative effect to be reduced.  So pick your diodes carefully.  Of course the diode behaviour depends on the signal level hitting them, and the resistors that set the gain of the booster and clipping stages also vary by +/-5%.  Since gain is multiplicative (e.g., a gain of 3 followed by a gain of 10 = gain of 30), and since there are two gain stages before the first set of clipping diodes, followed by another gain stage that uses additional clipping diodes, that 5% "error" can easily result in a reduced amount of clipping.

3) Op-amps themselves do not have any gain.  They do have various properties, such as as noise, or the capacity (or lack thereof) to produce X amount of gain at such-and-such a frequency, but their gain is given by the components around them, not by the chip.  The 4580 is a nice quiet chip.  I built a King of Tone for a buddy, and I have to say the 4580 made a pleasing improvement in the noise level.  Not really any different, tonewise, than many other chips, but nicely quiet for a high-gain overdrive.  It could be a good choice for the Upper-decker.

[Gus]

Looks like jfet input opamps  would work the best if the link Mark posted is correct.

Sound demos are recorded, so you have the amp and the microphone used sound change, EQ and what was done to the recording?  You also have your headphones or PC speakers or ? that you are hearing the sound with
How was the demo recorded?

[seedlings]

I haven't played with 4580s before, so I wasn't sure if the circuit was exploiting them for part of the tone.  I ended up increasing the feedback resistors on two of the stages, and bypassing one 470k/470k divider with a 500pf bright cap, and reducing the values of a couple feedback caps.  Now it's on.

CHAD

[seedlings]

The 4580D chips came in.  They are much more agressive in this circuit than Tl072, 4558, lm833 or ne5532.

CHAD

[Mark Hammer]

That won't be because they have more "gain".  It may be because they can manage a little more treble at the same higher gain.  A buddy had heard that 1458s were preferred for the Timmy and wanted me to do the swap for him.  So, he brought his pedal over, I installed a socket, and we tried a bunch of different dual op-amps.  In the end, he preferred the 1458, and that would have seemed to be because it simply couldn't deliver the top end at higher gain settings, resulting in a "smoother" tone.

Not trying to be a fuddy-duddy here, but it is important to understand why a chip choice produces the outcome it does, so that intelligent choices can be made, and expectations kept realistic.

[seedlings]

That won't be because they have more "gain".  It may be because they can manage a little more treble at the same higher gain.  A buddy had heard that 1458s were preferred for the Timmy and wanted me to do the swap for him.  So, he brought his pedal over, I installed a socket, and we tried a bunch of different dual op-amps.  In the end, he preferred the 1458, and that would have seemed to be because it simply couldn't deliver the top end at higher gain settings, resulting in a "smoother" tone.

Not trying to be a fuddy-duddy here, but it is important to understand why a chip choice produces the outcome it does, so that intelligent choices can be made, and expectations kept realistic.

That's why I used the word 'agressive' this time. Your points are well taken.  The gain bandwidth product for njm4558d is 15MHz, compared to 3MHz for a tl072.

CHAD