Zvex - Nano Head

Tube or solid-state, this section goes to eleven!
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Fuzzer
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Post by Fuzzer »

My friends, I have no understanding of this matters, and I have to stress that I'm not ZVex admirer. But, what is the problem if at the end of the day the nano amp is supposed to be used with guitar speakers? It's a guitar amp, after all, no?
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Post by analogguru »

For an FCC/CE-approval it is important. Everything above 10 kHz is HF-emission when radiated. Since the speaker wires are unshielded and there is an ultrasonic (> 20kHz) signal on them - let´s say 40kHz/1W - this is a (small) long-wave transmitter where I doubt that it fullfills the FCC/CE-requirements.

Another point is that this ultrasonic signal may overload the amp and/or cause intermodulation. If the power supply is really that dirty the countermeasure is simple done with a chcke and an electrolytic. But I doubt that the same way as I don´t believe that the SHO was derived from a Neve-console or Zvex has ever seen one.

I suspect that it is more introduced from a ground loop - but you can be sure that I won´t buy a Nano-Head to analyze it. Better take a reverb-driver-transformer from a Fender-amp and build a decent construction.

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Post by MKB »

analogguru wrote: Under this circumstances I wonder how this kitchen-table-designer could get a FCC-approval or CE-certification for his junk-products.

analogguru
I'd be surprised if he got approvals for it. We have to do this for our products and it is expensive and difficult.

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Post by rackham »

Don't you self-certify for the CE thing though?

I was thinking about this the other day, how do things like electric kettles get certified as OK for sale these days? A big electric element in a metal container that you're expected to fill with water...and that you could easily stick your hand in, were you so inclined/stupid enough. :shock:

Next to that, a guitar amp seems like a pretty safe bit of kit.

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Post by earthtonesaudio »

Like AG said, all it would take is a simple LC filter on the output, and you wouldn't have to worry about RFI being picked up by, oh I dunno, the microphone that you are using to record your guitar cabinet with?
Look at it this way: if you're listening to a recording of a Nano, you might fry your tweeters.

That makes it a problem at the end of the day.
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Post by Fuzzer »

Thanks for the explanation AnalogGuru.

What is the basis for the 'recording of a nano' statement?, the recorded cabinet would just reproduce a range of frequencies in which the ultra high frequency signals are not included.
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Post by soulsonic »

Fuzzer wrote: What is the basis for the 'recording of a nano' statement?, the recorded cabinet would just reproduce a range of frequencies in which the ultra high frequency signals are not included.
The RF radiation coming from the Nano Head itself could very easily interfere with the recording equipment in ways other than sounds coming out of the actual speaker.
It's basically a little radio transmitter, and if it transmits it's junk into too many things, it could very well be considered an FCC violation because it could be interfering with legitimate broadcasts. And the overall sloppiness of the circuit brings up a potential shock hazard from the high voltage. It's a sloppy design that doesn't conform to the professional (and possibly, legal) standards established for circuits of this type.
The UL would never approve something like this.
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Post by Fuzzer »

Thanks Soulsonic, I still have to get my RF electronics course, I guess. I didn't doubt the hazardous nature of the lousy PS and its interference into some frequency bands though.

Thanks again.
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Post by lmlacoss »

Uh, couldn't this problem just be alleviated by a simple low pass filter? If so, then you'd have to figure that Zvex ought to have incorporated that into his design. It's a pretty basic/standard circuit bit.

I think that my mind has been sufficiently blown.

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Post by Fuzzer »

If the power supply is really that dirty the countermeasure is simple done with a chcke and an electrolytic.
written by analogGuru.
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Post by RnFR »

lmlacoss wrote:Uh, couldn't this problem just be alleviated by a simple low pass filter? If so, then you'd have to figure that Zvex ought to have incorporated that into his design. It's a pretty basic/standard circuit bit.

I think that my mind has been sufficiently blown.

this is what i was initially thinking as well, but i believe that as a LPF would filter out the frequencies when recording direct, it would not take care of the potential RF problems.

mind blown as well. a zvex amp- 400.00????
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Post by earthtonesaudio »

I believe one of two things can explain this:
1. Either Zvex doesn't know how to fix the problem, or
2. He/they know how to fix it, but doing so would be cost prohibitive and/or not fit with the overall design goals of the amp
Or maybe...
3. They maliciously want to pollute the already congested airwaves with more RFI...???

But, an L-C lowpass for 27kHz could be quite small, and not interfere with the audio whatsoever. It could probably start rolling off as low as 10kHz and no one would notice the difference at the guitar speaker...
Then again, maybe they have tried to fix it, and it's still a problem in spite of their best efforts.
rocklander wrote:hairsplitting and semantics aren't exactly the same thing though.. we may need two contests for that.

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Post by MKB »

There's another nasty possibility with the lowish frequency interference from a switcher supply; if you have a lot of ultrasonic energy from one piece of equipment, and it interferes with another piece of equipment with a switcher supply of a similar frequency, you can have intermodulation of the noise that is no longer outside of the audible range. That could get very nasty really quick. That's one good reason to do something about the noise.

So, how much of this noise is getting dumped back onto the power line?

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Post by RnFR »

if i bought one i think i'd be kinda bummed that you couldn't go direct with it. i would probably mainly use it in the studio, and direct bass would be one of the options i would hope to be able to use this thing for.
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Post by culturejam »

Okay, I still want one of these. :lol:

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Post by JiM »

earthtonesaudio wrote:Also I think the pc board is a 6-layer affair. Props to anyone who takes the time to trace that thing. Probably full of buried/blind vias. :roll:
Damn, we'll need x-rays to trace that ! [smilie=new_microwave.gif]

Seriously, there's absolutely no reason for more than 2 layers here, all we need is a solder-side gutshot and components values ...
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Post by culturejam »

JiM wrote:Seriously, there's absolutely no reason for more than 2 layers here, all we need is a solder-side gutshot and components values ...
I would LOVE if this was the next Tracer's Fund purchase.

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Post by soulsonic »

culturejam wrote:
JiM wrote:Seriously, there's absolutely no reason for more than 2 layers here, all we need is a solder-side gutshot and components values ...
I would LOVE if this was the next Tracer's Fund purchase.
But it's a crap design that outputs a bunch of RF noise.
Why not a new design that gets similar sounds?
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Post by vanessa »

soulsonic wrote: But it's a crap design that outputs a bunch of RF noise.
Why not a new design that gets similar sounds?
Exactly. Make it a little bigger and 10 times better? What would you rather have?

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Post by bajaman »

As a side note - The Blackstar Dual HT pedal uses a very elegant switching power supply system - I have reversed it and will put it up in a new DIY ready to build project thread very soon for all those folks that would like to get 300v DC from a 15v DC supply rail. But be careful :!: - 300v DC can give you more than a little "tingle" :wink:
stay tuned
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