Thanks. I found an old one I had with 3dB and 18 steps a little too brutal.
Oh, btw, in old past time, 47K was the standard for line input impedances of amplifiers. It seems nowadays, this standard is obsolete and 10K more usual (I have to recalculate with the load of the amp). Is this right ?
If you agree, just we need to add a single parallel resistance at the output of the pot to adjust-it to a higher load impedance of 47k or 100K.
An other question I do not have the answer. 1dB was set for being the smallest difference in volume human can feel. Is this independent from the global volume (loud or very little) ?
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Talk about electromechanical porn!!! I'll bet those cost a pretty penny...
The best switches like the Shallco and others feature a detent mechanism which have multiple wipers which lift between positions to achieve a no-shorting action, then they allow a couple of degrees of wiping once on contact. Given the sliding wiping action, I wonder if even hard gold can match solid silver in this usage; anyone have data on this? I know many military switches are silver Shallco, but I'm sure they use others as well.
My work-study job when at UMASS EE school was with the 5-College Radio Astronomy lab (Five College Radio Astronomy Observatory - Wikipedia) which was a fascinating job, and sometimes I was tasked with salvaging expensive parts from old Gov't surplus eq for radio telescope eq builds...I saw some Shallcos that were actuated so many times there was a groove in the contact pad, but they still had extremely low and stable resistance.
Anyway, while building these Shallco stepped potentiometers a few years ago I worked up an Excel resistance calculator. It is not a constant-impedance calculator, but if anyone is interested in it PM me.
Cheers!
Howie
I am lucky enough to have some Shallco switches, but they don't have any lifting mechanism. One is make-before-break, and the other simply uses unconnected contacts between positions to give break-before-make. The extra contacts cannot be used because the detent passes over them and they have no solder lugs.
This is the real deal: Eric Clapton: The Rolling Stone Interview:
"Two 100-watt Marshalls. I set them full on everything, full treble, full base and full presence, same with the controls on the guitar. If you’ve got the amp and guitar full, there is so much volume that you can get it 100 miles away and it’s going to feed back – the sustaining effect – and anywhere in the vicinity it’s going to feed back."
It also permanently transform your aural perception. 🙂
Yes, it is like when you have tasted the best wine of your life and every others seems insipid after that, after two hours in front of a double Marshal 100W, every sound seems dull ...except this whistling in our ears.
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I did follow spot operating on two Rolling Stones shows.
The ceiling height walkway position that I was working from was directly inline with Keith's tilted back two famous Fender Tweed combo amps and about 80m distant.
From my position these things together were insanely loud and penetrating even with production talkback headset over my ears.
One of the road crew commented that during setup 'who needs so much power, so loud'.
I have watched ACDC roadie soundcheck where the guitar tech struck a chord and took a couple of minutes to scan all over the stage.......instrument stacked quad boxes plus 40+ kW of Crown amps driving foldbacks/sidefills ensured that the lead guitar fed back over every square inch of full sized stage.
The ceiling height walkway position that I was working from was directly inline with Keith's tilted back two famous Fender Tweed combo amps and about 80m distant.
From my position these things together were insanely loud and penetrating even with production talkback headset over my ears.
One of the road crew commented that during setup 'who needs so much power, so loud'.
I have watched ACDC roadie soundcheck where the guitar tech struck a chord and took a couple of minutes to scan all over the stage.......instrument stacked quad boxes plus 40+ kW of Crown amps driving foldbacks/sidefills ensured that the lead guitar fed back over every square inch of full sized stage.
Yeah and copies and others....and truss follow spots plenty too.
Nowadays truss spots are remote control from backstage.....OHS.
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I use the motorized version - sorry I should have made it clearer - that's the problem.
About 15 or 16 years ago my younger son (who is now 31) was in a band playing bass and invited my wife and I down to the local pub in Buxton, England to hear them play.
Big mistake.
That's where my hearing hit a tipping point. They rang for about three days after that and I ha d tinnitus for weeks. The trick I learned after that is to always carry some clean toilet paper in your ear for emergencies and make sure there was a glass of water handy. When you suspect the music is going to get loud, wet the toilet paper and shove it in your ear canals. Works a treat although is kills anything above about 3 or 4 kHz.
I used it at Sting gigs in Tokyo and in Taipei. My older son has introduced me to special earplugs that attenuate the SPL without any (or minimal) loss of frequency response.
Next time that happens run, don't walk to you local health food store and get l-carnitine, N-acetyl cysteine, Alpha-Lipoic Acid and B-complex. Take those daily for a week or two. It really helps even post event.
I used to do that when I mixed live bands many moons ago.
The look on the audience's faces when they realized the sound man had toilet paper sticking out of his ears was priceless. 🙂
But did you use WET toilet paper, Zung? I didn't and I was exposed with the Wall of Sound system with the GD for a year or so. I only had my ears ring badly once, and this was before the WOS when we used similar woofers but JBL horns on top. It was a special night when Janis Joplin sat in the the Grateful Dead, in 1970 and I was working the gig, but on LSD (always available). I will NEVER forget that performance! One of my bosses commented that I personally had finally come to realize what everybody was working toward. I know there was some damage, working that scene, but amazingly everyone I ever worked with in the GD scene seems to hear pretty darn good for their age. Why, I don't know.
When I got drafted in the USArmy, the firing range was all done withOut ear plugs.
About a month into basic training, the Army was told too many are loosing their hearing and afterwards we were issued ear plugs. I knew about hearing damage and had used pieces of cloth stuffed in my ears.
But of course in combat, you cant use ear plugs - you need to hear commands etc.
The high peak transient levels is what damaged so many peoples hearing. I have often wondered about drummers, also.
-RNMarsh
About a month into basic training, the Army was told too many are loosing their hearing and afterwards we were issued ear plugs. I knew about hearing damage and had used pieces of cloth stuffed in my ears.
But of course in combat, you cant use ear plugs - you need to hear commands etc.
The high peak transient levels is what damaged so many peoples hearing. I have often wondered about drummers, also.
-RNMarsh
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