Audiophoolery?

"Brian May", who ?? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.

Den onsdag den 22. november 2017 kl. 22.05.31 UTC+1 skrev Jim Thompson:

I know are ancient but Bohemian Rhapsody came out more than 40 years ago ;)

Why do it "in analog" when you can get something like this that lets you mix and match about two dozen different amp/speaker cabinet models, plus multieffects, all done with DSP and battery powered. Just plug in your guitar and headphones

Whoops:

Granted no Hi Fi purist would ever touch a similar product made for Hi Fi

40 years ago I was almost 40 ;-)

I'm of the Elvis, Everly Brothers, Fats Domino, Bill Haley... old style rock 'n' roll era. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.

Strobe for turntable speed does not ensure proper pitch. Analog tape machin e sources can be quite different. I bought a CD of E Power Biggs Bach on a Columbia. The pitch of each track was different. A little time in Adobe Aud ition and that is no longer a problem. Point is even the pros screw it up. I only mess with LPs if there is no other option.

Can you still get a decent cartridge? The Shure V-15 V was the best moving magnet by far but even if you could find a New Old Stock it wouldn't be wor th diddly because the internal rubber parts will be hardened and no longer usable. Ticks, pops, mistracking, surface noise, holes off center (wow). I sure don't miss that

The strobe wheel was good enough when vinyl disks were in fashion. I mentioned the strobe wheel because replacement idlers are rarely exactly the same size as the original and do require some speed tweaking. New belts do not affect the speed but it doesn't hurt to check anyway.

What level of pitch accuracy were you trying to achieve? Without a test tone and test equipment, I can't tell if the pitch is off on any given cut. I can't check speed by just the music. I don't have perfect pitch and can't tell by ear. Are you suggesting that listeners are now expected to adjust the motor speed individually for each track?

If you're blessed with perfect pitch, I'm jealous.

Is this good enough? Only $15,000.

It's fairly easy to obtain replacement cartridges and needles for a modern commodity USB turntable. I find them all over the web from a multitude of sources. If a needle cannot be found, there are alternative plug compatible cartridges available. You're correct about old cartridges that are no longer being manufactured. I don't see much of a market for legacy replacement needles and would expect the available supply to be rather limited.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Den fredag den 24. november 2017 kl. 17.11.25 UTC+1 skrev Jeff Liebermann:

afaik more LPs that CD are sold now and new vinyl-pressing factories are being build to keep up

He's that other guitar player, that also knows a tad about physics...

-- Kevin Aylward

- SuperSpice

I did encounter decks that were off speed. Sellotape soon fixes that ;)

Lol. And a strobe disc for $225

Audio technicas seem to be commonly available, I never much liked them. Shu res not so easy to find or expensive.

FWIW I'd not expect problems with NOS. I checked a box of old carts recentl y including some Shures, and the few I prodded were still fine.

While vinyl was still in use I found a supply of goodish carts for a few po unds each. Compared to various middle of the road carts of the day it stood its ground. Still got 2 or 3 left in stock somewhere.

NT

exactly the same size as the original "

Doesn't matter. Only the diameter of the driven surface and the driving surface determine the speed ratio from motor shaft to rim.

I beg to differ. If that were true, we wouldn't need to adjust the platter speed. The drive surface is brass and the platter is aluminum, which do not change. If the idler diameter made no difference, the speed would be constant.

Let's try a trivial example using gears instead of turntable parts. The spindle motor "gear" had 10 teeth, the idler has 30 teeth, and the turntable has 100 teeth. By your logic, the turntable would spin at the same speed, no matter how many teeth on the idler gear.

Gear_ratio = 10 * 30 * 100 = 30,000:1

Now, I change the number of teeth in the idler, which is the same as changing the rubber idler wheel diameter to 50 teeth.

Gear_ratio = 10 * 50 * 100 = 50,000:1

Looks like a different gear ratio. If I drove these gearboxes with the same speed motor, the output speeds would be very different.

Also, there are plenty of ways the idler wheel can deteriorate and affect the speed and stability:

If the idler has two rubber wheels, the ratio between these two diameters partly determines the speed.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

you screwed up somewhere, no matter what size of idler gear when the motor moves 10 teeth, and so does turntable so the ratio is the same

or with a rubber idler the small input might squeeze the rubber more than the large output so they are running at slightly different effective radius

That CD contains tracks from Bach Organ Favorites various volumes recorded years apart. Obviously no consideration was given to correcting the pitch when the CD was made. Some other old analog material made into CDs was prop erly processed and the track to track pitch is consistent. It all depends o n the engineer and the folks paying the bills.

Well the price is impressive.

Shure were the ones touting the 'trackability' of cartridges. Back in the 7

0s and 80s I worked in consumer audio and had access to most of the mainstr eam cartridges and all fell short. The first one I bought that was definitely audibly superior was the V-15 type IV. When I bought the typ e V the improvement over the IV was even bigger than the type IV over previ ous cartridges. I can't imagine that any USB turntable has a cartridge worth me ntioning.

...

The speed does not depend upon the idler diameter (number of teeth in your example).

The ratio is multiplied one way from the motor spindle to the idler then the other way to the turntable.

The actual ratio in your fist example would be 10 * 30 / 30 * 100. So the ratio from motor to turntable is independent of the idler diameter.

I have never seen a design with a stepped idler - they always have had a stepped motor shaft. It would be difficult to guarantee good speed accuracy with the poor dimensional stability of rubber.

It is important that the idler has constant diameter or it could introduce flutter.

kevin

Maybe you need to reconsider your thinking processes ?>:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.

From Wikipedia:

An idler gear does not affect the gear ratio between the input and output shafts. Note that in a sequence of gears chained together, the ratio depends only on the number of teeth on the first and last gear. The intermediate gears, regardless of their size, do not alter the overall gear ratio of the chain. But, of course, the addition of each intermediate gear reverses the direction of rotation of the final gear.

Likewise, the size of an idler wheel in a non-geared friction drive system does not affect the gear ratio between the input and output shafts. The surface speed of the input shaft is transferred directly to the surface speed of the idler wheel, and then from the idler wheel to the output shaft. A larger or smaller idler wheel maintains the same surface speed (which equals the surface speed of the input shaft), therefore the output shaft is driven at a constant speed regardless of the size of the idler wheel.

See also

[snip]

I just had an amusing thought... what would audiophools pay for and amplifier with a switch: "toob emulation" or "low distortion" ?>:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.

I think there is the confusion: calling the tiny _drive_spindle_ an "idler"... it's not an idler pulley.

The "speed" of the platter is simply DiaSpindle/DiaPlatter*MotorRPM. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
     It's what you learn, after you know it all, that counts.