Question about volume "tapers"

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telegraph1101
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Question about volume "tapers"

Post by telegraph1101 » Tue Jul 31, 2018 7:00 pm

Hi everyone,

I was reading about the Fender Michael Landau Hot Rod Deville (supposedly very different from the regular Deville). According to owners of this amp, once you get past a certain volume (about 5/12 or halfway), it stops getting louder, and instead becomes more compressed and distorted.

Do amps normally work like this? I read that it has to do with what are called "volume tapers" (not something I'm familiar with). I just thought it was weird, as if "half the volume" is wasted if it stops getting louder past the halfway mark.

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Re: Question about volume "tapers"

Post by oid » Tue Jul 31, 2018 9:24 pm

Nothing to do with taper, the tube just hits clipping at that point, no more volume, just more distortion.
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Re: Question about volume "tapers"

Post by sessylU » Thu Aug 02, 2018 12:03 pm

There was always a rumour that certain amps would have a weird taper on the volume knob (anti-log?) so that most of the actual range happened in the first quarter or so of a turn. People would try them out in shops at polite, shop volume and conclude that if the amp was as loud and clean as they were hearing with the volume knob only a quarter way up, it would be really loud with it all the way up.

Then they'd buy it and be disappointed at band practice when they realised that it doesn't get any louder.
a total idiot jackass

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Re: Question about volume "tapers"

Post by oid » Thu Aug 02, 2018 1:34 pm

sessylU wrote:
Thu Aug 02, 2018 12:03 pm
There was always a rumour that certain amps would have a weird taper on the volume knob (anti-log?) so that most of the actual range happened in the first quarter or so of a turn. People would try them out in shops at polite, shop volume and conclude that if the amp was as loud and clean as they were hearing with the volume knob only a quarter way up, it would be really loud with it all the way up.

Then they'd buy it and be disappointed at band practice when they realised that it doesn't get any louder.
That is not all that uncommon on master volume amps meant for distorted/hi gain styles. It gives you more control over the distorted tones of the amp, generally it is a linear taper, but anti-log works as well, just in a different fashion. These are terrible for attempting to use a big amp at bedroom levels and can give some one a flawed perception of its power, but quite handy in the situation they were designed for.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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Re: Question about volume "tapers"

Post by telegraph1101 » Fri Aug 03, 2018 9:38 pm

Thanks for the replies everyone.

Just a question: these days, I'm looking forward to getting a Hot Rod Deville, despite knowing that I might have to change the volume pots (I just like the sound of that amp, so I'm willing to make that small volume mod). Apparently, the volume goes from 0 (off) to 1 (excruciatingly loud), and this can be remedied by installing audio tapers. But whether I use audio or linear tapers, the total possible volume will stay the same, right? IE the max volume at 12 will be the same regardless of the taper used, it's just that the tapers affect how gradually the volume will increase?

My apologies, I know nothing about electricity and amp technology...

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Re: Question about volume "tapers"

Post by øøøøøøø » Sat Aug 04, 2018 5:32 am

We're conflating two issues here.

One-- tube amplifiers, if turned up enough, will reach a point where they simply won't get any louder--first they compress and fatten (which is still harmonic distortion), then they hard-clip (audible as distortion, or crunch).

Two-- loudness is perceived by the human ear logarithmically, not linearly. The decibel (the most perceptually-intuitive measurement of sound pressure for humans) is a logarithmic measurement unit of measure. Twice as many pascals of pressure variation translates to only a few decibels. In other words, doubling power makes it seem "a little bit louder," not twice as loud.

Voltage (used as an analog for sound pressure in tube amplifiers) is a linear measurement. So doubling output at the amp increases volume by only a few decibels, or "a little bit louder".

To make the volume control (which controls signal voltage) behave intuitively, we use a log-taper pot (also known as "audio taper"). If we use a linear taper instead, it will behave strangely... with a lot of the pot's usable range being in one very narrow band... it will be fiddly, with a range of the pot not doing much, and then a sudden big jump. It's not an enormous effect, somewhat subtle, but it does make the control less-intuitive to use.

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Re: Question about volume "tapers"

Post by oid » Sat Aug 04, 2018 10:16 am

Fenders hot rod series amps are one of those with the linear master volume, only that one pot would need to be replaced, both the drive and the gain pots are already audio tapers.

But if you play in a band I would give it a shot stock though, it is increadably useful at giggling levels.
Logic gates based on billiard-ball computer designs have also been made to operate using live soldier crabs of the species Mictyris guinotae in place of the billiard balls.

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