So, I've down all sorts of things to my RE-101 Space Echo to make it less of a hiss and hum factory which I believe lets more of the tapey goodness shine through. Ditched the terrible low impedance bandpass filter on the input in favor of a Mini-Booster, re-capped it, replaced any noisy transistors, added a better output buffer, shielded stuff, built up the power supply and filtering, and just general making stuff better here and there.
Problem is that sometimes I miss the hiss when sending it into self oscillation, when the hiss was around it went into oscillation a lot easier because of the self noise signal already present and had this whooshing wind sound that was just awesome. I was thinking about building a circuit to add the hiss back in when I want it and the From PA jack is useless so I can put a pot there for level and if I need a switch, I can use the hole where it kills the echo because that is also useless being that I just use the footswitch.
Anybody got a good simple hiss circuit?
That is the strangest problem :icon_lol:
Frequency Central did a white noise.. hiss.. type thing on here somewhere. A wind noise maker. I'm blanking on the actual name.
http://www.diystompboxes.com/smfforum/index.php?topic=105885.msg955626;topicseen#msg955626
Perfect.
Thanks guys.
I know it's a strange problem, but sometimes the imperfections of things are what make them great and you miss them when they're gone. I just want to be able to turn off the noise when I don't want it.
A radio, tuned between stations?
Al though I suppose it depends on where you live. Some regions don't have that many blank spaces between adjacent stations.
In case you want to get all fancy schmancy with true white and pink noise, here's a white noise generator:
http://edn.com/design/analog/4420926/White-noise-source-flat-from-1Hz-to-100kHz
And a pinkening filter:
http://www.diystompboxes.com/smfforum/index.php?topic=81602.msg944432#msg944432 :icon_redface:
Or, you could use a single 8 pin IC to do it. The article Merlin references mentions a 12C508 PIC to do it. I did my own version of that, but customized for long-term uncorrelated noise.
From last May: http://www.diystompboxes.com/smfforum/index.php?topic=102782.20 (http://www.diystompboxes.com/smfforum/index.php?topic=102782.20) See the next to the last post.
A 10F200 is cheap, and if I did the math right you get white noise that doesn't repeat for nearly two million years. :icon_eek:
Zeners and broken base-emitters are OK, but 9V is marginal, and you have to amplify the noise to get it up to a usable amount.
... presumably with vintage carbon comp resistors! :icon_lol:
http://sound.westhost.com/project11.htm (http://sound.westhost.com/project11.htm)
Another simple white noise generator - filtered to make pink noise.
The broke-down emitter is marginal at 9V. Hageman/EDN uses a 12V Zener with 18V supply to reduce 1/f noise. The old-old for-purpose chip is hard to find. Using a CPU (even a $1 job) seems overkill, isn't in my drawer, long repeat is probably not essential here, and needs programming.
My TL072 approach should work (TL072 is reliably hissy<g>). It may need a lot of side parts but they are all in a well-stocked drawer. The 1/f noise "flaw" is a partial virtue because we can use smaller capacitors.
There is the question of how well the 1/f noise corner is known. The plot in the specsheet is not guaranteed and not tested except grossly (if other tests are wobbly because of 1/f noise they may look into it). If 1/f gets better with newer Silicon process they won't bother to change the specsheet. So if the 1/f corner moves to 50Hz on new parts, and my cap values assumed the old 200Hz(?) corner, there will be a few-dB dip around 100Hz. This would be poor for Hageman's use. I doubt Wavley would notice, since he just wants "some" hiss to shorten the start-up time of his echo oscillations.
I've wondered what Wavley needs for "pinkening". The hiss he removed to get into this problem was probably mostly flat with some 1/f, or else a 6dB/oct integration tape preamp. Frankly I think he should K.I.S.S. and just do a hard high-cut at 1KHz. The sub-KHz wobbles should start his oscillation quick enough, and there's little treble-hiss to annoy the ear.
Did someone say simple?
http://darrenyates.com.au/electronics/archives/40
I think any npn will work, maybe upsize the output cap for more pink..
Power a booster with a cheap & nasty SMPS wall wart. ;D