This Week on the Breadboard: The Danelectro Nichols 1966

[Chuck D. Bones]

According to the Danelectro website, this circuit was designed in 1966 by Steve Ridinger, a resident of Nichols Canyon in Hollywood Ca., who would later go on to found Foxx pedals. This circuit was created out of thin air, and it kinda looks it. Sounds great right outta the box. The only mod I came up with was to replace C8 with 15nF and make the MID switch ON/OFF/ON. C8 = 1nF does nothing audible. C8 = 15nF provides some treble cut when TONE is below noon, without the mid scoop. The two gain controls (FUZZ & DRIVE) provide a huge range of gain and tone. With FUZZ & DRIVE dimed and TONE at noon, the gain is around 70dB. There is not a lot of compression, due to the asymmetric clipping and large headroom. The way this circuit is biased, all three transistors are right at the edge of saturation. Low FUZZ & DRIVE settings produces a warm distortion with just a few harmonics. At higher settings, the clipping becomes more and more asymmetric, producing a large amount of high-order harmonics. Note decay is smooth, no sputtering or gating. I built this to see if it could approximate the Spirit in the Sky tone. It doesn't. But there are plenty of vintage-style distortion and fuzz tones available. The volume changes quite a bit as TONE is rotated.



I subbed 2N5210 for Q2 & Q3. Q1 is bottom right, Q2 & Q3 are to the left of Q1.

Knobs (L-R): MiD sw - VOLUME - TONE - DRIVE - FUZZ

 

[bluedmc777]

I built one of these stock a few months back and have really enjoyed it. It can do a little bit of a lot.

 

[Chuck D. Bones]

Which MID switch setting do you prefer? "Mid Cut" or "Stock?"

 

[gonzo]

I breadboarded this one a while back. I really liked it. Might have to build it.

 

[bluedmc777]

Which MID switch setting do you prefer? "Mid Cut" or "Stock?"

I’ll play it when I get a chance tonight. I know my switch is in the down position almost always if that helps. Probably mid cut if I had to guess but I thought the switch made a noticeable difference in tone. I’ll give my .02 when I can actually play it

 

[bluedmc777]

Which MID switch setting do you prefer? "Mid Cut" or "Stock?"

I like both but use it in mid cut setting the most. It’s such a cool unique sounding fuzz-stortion. Curious what you cook up with this.

 

[Chuck D. Bones]

I might fiddle with the TONE network a bit, that's about it.

 

[DDad]

What causes the clipping to be asymmetrical? Easy to understand with parallel diodes, not so easy to see in this circuit to me.

 

[Chuck D. Bones]

Class-A circuits* will naturally clip asymmetrically because the active device, in this case, the three BJTs, can only sink current. They pull down harder than their collector resistors pull up. Even if we center the bias, the shape of the tops and bottoms of the clipped waveforms will be different. The tops will be rounded and the bottoms will be flat and more abrupt. In the Nichols, all three transistors are biased close to saturation. Their collector voltages are near 1V. The bottom half of the waveform will be flattened while the top of the waveform may have very little distortion. The result is both even and odd-order harmonics. At low FUZZ & DRIVE settings, there are very few harmonics, mainly 2nd & 3rd, producing a warm amp-like tone.

* Class-A amplifiers are defined and having a single active device, as opposed to push-pull. In a Class-A amplifier, the active device is biased so that it always conducts.