# Two problems/questions with EH Neo Clone



## raimundo (Sep 30, 2010)

Hi guys, I recently bought a Neo Clone chorus pedal and I have to say I really like it, nice size, cool sounds and for a good price. Nonetheless, when I turn the pedal on I noticed two things, first, my signal gets a little bit noisy, I have to say that when I plug my guitar directly into my amp there is some hum there but is not very noticeable, except if you stand pretty close to the speaker, but now you can clearly hear it. The second issue is that my guitar feels more sensible to the attack of the pick or actually with whatever I'm using to hit the strings, its like as if more treble is added to the signal.

Any idea on where the problem could be? I have already used it through the effects loop and directly into both inputs of my amp (Bugera V22).

The guy in Tom Lee told me that this pedal isn't true bypass, maybe it has something to do with that? is it possible to make it true bypass?

Thanks!
Raimundo


----------



## mhammer (Nov 30, 2007)

1) The guy at Tom Lee is likely correct about the Neo Clone not being TB. The schematic for the re-issue Small Clone (which used through-hole components, rather than the surface mount type the NEO series uses) uses a single pole switch to turn a switching FET on and simultaneously turn an LED on. This engages and disengages the _effect_, but does not bypass anything whatsoever. Boss and many other companies have been using this same strategy since the dawn of chorus/flanger/phaser pedals. The input and output stages of the pedal always remain in-circuit, so there should be very little difference in hiss or hum whether the effect is in or out. Bottom line: the switching has nothing to do with the hum.

2) Not all adaptors are created equal. Is it possible you are powering the pedal with an adaptor that has inadequate regulation to smooth out the AC and make it more battery-like? Is the NEO Clone sharing the power source with something else that may be introducing hum?


----------



## raimundo (Sep 30, 2010)

Hi mhammer, first of all thanks for your response. I am powering my Neo Clone with the 9v battery that came with it. I also have a Boss PSA-120S adaptor that I bought for a Boss DD3 Delay.


----------



## mhammer (Nov 30, 2007)

Okay, the other aspect of your initial post concerns what seems like an apparent change in tone to your ears.

Because the Neo Clone is not true bypass, your guitar is always buffered. The buffering will naturally introduce a little more treble brightness than you might experience just plugging the guitar directly into the amplifier.

As well, the Small Clone uses pre-emphasis/de-emphasis, a kind of "poor man's Dolby" to keep noise levels low. This involves boosting the treble before it gets fed to the delay chip, and then cutting back on the treble, to restore tonal balance. Although the treble cut will reduce the level of any hiss or clock whine from the delay chip, because the guitar signal was treble boosted first, the delay-chip noise will be more affected by the treble cut than the guitar is.

While this is an effective system, and something that many companies use (not just EHX and not just for the Small/NEO Clone), keep in mind that the same companies also use resistors that have a +/-5% tolerance and caps that have an even wider tolerance, so it is always possible that you particular pedal provides more treble pre-emphasis than complementary de-emphasis, leaving you with more treble than you put in. I am not saying that is exactly what is happening with your pedal, but it is a possibility.

There IS a way to fix that by adding a part, but I don't know how able you are to do that, and how much the layout of the NEO Clone permits it (it uses a combination of surface mount and through-hole components). Let me know and perhaps I can guide you through it.

As for the hum, from what you describe, it seems the adaptor is not the issue.


----------



## raimundo (Sep 30, 2010)

Thank you man!, I am certainly not skillful enough to add that part you mention, but I will try to find somebody to do it here in Van. By the way, what part is that?

About the hum, I've heard that chorus/flangers or modulation effects in general tend to be noisy, do you know if, to some degree, this is true?


----------



## mhammer (Nov 30, 2007)

raimundo said:


> Thank you man!, I am certainly not skillful enough to add that part you mention, but I will try to find somebody to do it here in Van. By the way, what part is that?
> 
> About the hum, I've heard that chorus/flangers or modulation effects in general tend to be noisy, do you know if, to some degree, this is true?


*Anything* that uses a clock can be noisy. The low-frequency oscillator that makes the effect sweep up and down is a sort of "clock" that can make a ticking sound. Delay-based effects use that low-frequency "clock" to drive a much higher-frequency clock, and THAT clock turns the "ticking" into a buzz or whine (which is just MUCH much faster ticking). So, it is understandable that chorus/flanger effects can be noisy.

There are a few general strategies for combatting this, that are built into the design:

1) The delay chip has two complementary outputs. When they are perfectly matched, it operates almost like a humbucker pickup, cancelling the noise but keeping the signal. Many manufacturers will "balance" the two outputs by simply using a pair of equal-value resistors. Some manufacturers will go the extra mile and use an internal trimpot to adjust for maximum noise cancellation, though this adds to the production cost because of parts, larger board footprint and labour (for doing the adjustment). The Maxon AD-999 used to use eight delay chips with a balance trimot adjustment for each one!

2) Delay chips often use what I described as the "poor man's Dolby" - pre-emphasis/de-emphasis - as a way of reducing the noise produced by the delay path. Some will occasionally use companding, which is a higher order of pre/de-emphasis that produces even more reduction/taming of any noise produced inside the pedal. Since that also adds cost and space-requirements, it tends not to be used very often, mostly when absolutely necessary.
The Boss DC-2 Dimension C chorus (and the Behringer clone of the DC-2) use it because they each have an _additional_ source of noise; what is referred to as "heterodyning". The DC-2 uses two counterswept delay chips, each with their own HF clock, driven by a shared LF clock. The two HF clocks not only produce whine/buzz at their own frequency, but can produce the sum and difference of the two frequencies as well; kind of a mini ring modulator at very high frquencies. So Boss had no choice but to use very strong noise-reduction techniques, and that meant bringing in a compandor chip.

3) The third strategy is to use strong, steep lowpass filtering, that provides a very abrupt treble cut of the delay signal to eliminate any hiss and/or remaining whine/buzz from the clock. Ironically, this is why analog delays are said to have a "warm" tone. The "warmth" is a product of having to use very strong filtering to keep the whine/buzz from the delay chip out of the output, resulting in very limited bandwidth, often rolling off around 2khz or so. Generally speaking, manufacturers aim for the best tradeoff in terms of noise and delay time with analog delays; the longer the time you try and squeeze out, the greater the risk of audible whine/buzz. You can get a brighter sound if you are willing to tolerate hearing the buzz-whine, or if you may the delay time short enough that the clock buzz/whine is well above the human hearing range. This is also why flangers have a brighter sound than chorus or delay pedals. They use the same kinds of delay chips, but because they aim for a much shorter delay time, the chips are clocked at much higher frequencies, and any clock noise is difficult to hear.


What part is it? On the output stage there are 3 components in the "feedback loop" of the last chip the signal passes through. One - a resistor - sets the gain, and two others - a resistor/capacitor combination - provides the complementary treble de-emphasis to restore tonal balance. In the schematic I have, those go between pins 6 and 7 of the chip. If you added another capacitor between pins 6 and 7, perhaps 1000pf (.001uf), that might trim an acceptable amount of treble off, reducing some of the hiss more, and making your guitar seem less bright when using the chorus. A 1000pf capacitor will result in treble rolloff starting around 4.8khz, which isn't too bad. If it's too much, drop down to 820pf, and if it isn't enough, try 1200pf or maybe even 1500pf.


----------



## Guest (Dec 29, 2011)

Have you thought about returning the pedal for a different brand that doesn't have your issues?


----------



## mhammer (Nov 30, 2007)

I have a Re-Issue Small Clone and a clone that I made, and don't find either to be problematic. So, you make a reasonable suggestion, but I'm sensing this may either be something about that particular pedal or how raimundo uses it, rather than anything about the brand.


----------



## raimundo (Sep 30, 2010)

Thank you guys.

I don't know if I want to change it because I find it to sound awesome, even when it boosts the treble and makes some hum, it was so cheap also. The curious thing is that when I tried it at the store I used a solid state amp and an Epiphone les paul, and I didn't notice anything of what I'm describing here.


----------



## Arjumand (Dec 30, 2014)

A decent compressor. You can use them as clean boosters E20-597 dump , and as overdrives, in addition to using them as compressors. It also adapts to a great many styles of music, which is more than I can say for most pedals.


As another thread here so well illustrates, many would consider reverb their go-to effect, though in most instances they don't think of reverb as a "pedal" so much as an aspect of a good amp.


I get the feeling, however, that you are asking a question of a somewhat different type.


----------

