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Does anyone know the spindle to pivot distance on the current 9" arm on the Orbit? I have emailed U-Turn but have not heard back yet. Thanks for any info!!Alan
Edits: 03/28/17Follow Ups:
I have heard from U-Turn and they have told my the distance is 7.61 inches. Does this seem right? I do not have my turntable yet to check but since that converts to around 193mm it seems a bit short. Thanks for any input!
Alan
I have heard from U-Turn and they have told my the distance is 7.61 inches. Does this seem right? I do not have my turntable yet to check but since that converts to around 193mm it seems a bit short. Thanks for any input!
Alan
The U-Turn tonearm is probably shorter than 9-inches. In other words, 9-inches is just a general length designation. All tonearms in-between 8.4" and 9.5" are called 9-inch tonearms. For example, my SME V is called a 9-inch tonearm but its effective length is actually 233.15-mm or 9.179-inches. Rega tonearms are also called 9-inch tonearms but have effective length of 9.33-inches. Therefore, perhaps the U-Turn tonearm has effective length of 8.4-inches, which would make it reasonable to have a mounting distance of 7.61-inches.If you want to understand U-Turn Orbit tonearm geometry, you need to ask them for at least three independent alignment parameters such as effective length, mounting distance and offset angle. Or, ask them to provide mounting distance along with both alignment null-points. As long as you have any three independent alignment parameters, you can figure out all the other parameters using the tonearm geometry equations provided below:
...........................
Edits: 04/15/17
The tonearm parameters expressed in terms of the null radii.
Best regards,
Hi Brian,
How's life in California?
Those tonearm alignment equations sure come in handy! ;-)
Best regards,
John Elison
Hello John,
California is different!
It certainly is a change here from North Carolina!
There are lots of interesting audio items to be found in the classifieds here.
There must be some audio events that I will be near now!
How is Kentucky?
Best regards,
Hi, Alan,The tonearm length you got from U-Turn does seem odd at first glance but it's maybe just atypical of entry-level tonearms. A mounting distance of 193mm would put the effective length of the tonearm at somewhere in the neighborhood of 208 to 211mm (8.2 to 8.3") assuming typical overhang distances of 15 to 18mm. I compared an image of the Pro-Ject Debut Carbon, which includes a tonearm with an effective length of 218.4mm (8.6") with an image of the Orbit and the two tonearms looked very similar in length. I didn't try to estimate a difference of 7 to 10mm using a a couple of small images from the web. :-)
Why do you ask?
Regards,
Tom
Edits: 03/28/17 03/28/17 03/28/17
Hi, Alan,Here's a comparison chart and graph of the differences between the U-Turn Orbit tonearm and the Pro-Ject Debut tonearm. The Pro-Ject 8.6 tonearm has an effective length of 218.5mm (8.6") and typical of Pro-Ject tonearms, is designed with the Lofgren A alignment geometry in mind. I don't know which alignment geometry U-Turn uses for the Orbit tonearm so I included the three most common alignment geometries, Lofgren A (Orbit A), Lofgren B (Orbit B) and Stevenson (Orbit S) for comparison to the Debut tonearm.
Chart and graph from VinylEngine.com's "Tonearm Alignment Calculator Pro".
As you can see, the difference in effective length (pivot-to-spindle + overhang) is only about 7mm (0.3 in), which makes the 7.61" mounting distance that U-Turn quoted you as being quite reasonable.
Regards,
Tom
Edits: 03/29/17
U-Turn updated their tonearm design late last year. From U-Turn's website:
"We have increased the effective length of the tonearm to allow for the use of Stevenson, Lofgren A (Baerwald) or Lofgren B geometries. Our original tonearm was only compatible with Stevenson. Each type of geometry has its benefits. For example, Lofgren B has the lowest average distortion across the entirety of the record, while Stevenson is best for reducing distortion on the inside of the record. With the new tonearm, we are now using Lofgren A as the default alignment for all Orbits (this is something that you can easily adjust if you prefer an alternative geometry)."
Hope this helps.
Hi, Jon,
Good information. Thanks for the update and link. Haven't heard back from Alan G. so we can probably assume that everything worked out fine.
Regards,
Tom
Thanks for all of the input. I have received a message from U-Turn and according to them the spindle to pivot on the new arm is 193mm with the effective length at 213mm. Does this seem consistent with the measurements you posted up thread? Sorry for all of the newbie questions!
Alan
Hi, Alan,
Here's what you get with the new alignment provided by U-Turn:
The overhang is about 2mm longer than typical 9" tonearms but as long as the headshell accommodates the needed stylus/cartridge overhang and offset angle it appears that U-Turn's revised geometry makes sense.
Enjoy the new turntable and let us know how it sounds.
Regards,
Tom
Thanks for all of the input. I have received a message from U-Turn and according to them the spindle to pivot on the new arm is 193mm with the effective length at 213mm. Does this seem consistent with the measurements you posted up thread? Sorry for all of the newbie questions!
Alan
Wow! Thanks for all of your work. This should really come in handy. I was just hoping there was an arc protractor available for the Orbit. With the latest arm they ship it with the Baerwald geometry. Thanks again!!
I recommend the "TemplateGen" alignment calculator and arc protractor from Conrad Hoffman. The .zip file download is available at the link below. His alignment protractor has been successfully used on a wide range of tonearm/cartridge combinations and there's all kinds of support, including a dedicated discussion thread at VinylEngine.com . It's the one I use for the two Pro-Ject tonearms I own.Tom
PS: If you decide to use Hoffman's TemplateGen protractor, be sure to read the "README.txt" notes. It's full of helpful advice on using the program and protractor.
Edits: 03/29/17 03/29/17
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