some plinth design renders.
1) light weight. layered baltic birch plywood builds
Still working on final details for this design.
This plinth will allow either one 12 inch tonearm or one 9 inch toneam to be mounted. Presumably, any effective length arm in between these extremes will work as well. but I plan on first a 9 inch tonearm; the black Zeta. Then, over time, I will explore other tonearms/cartridges to see where the turntable's strengths are.
It only incorporates Baltic Birch in its build.
Finish will be multi-coats of lacquer.
Probably, in black.
I plan on making the first armboard out of purple heart. More details later as I develop them.
here is a top view dimensional layout:
Please note. Above drawing is readable on 11 x 17 (US B size) plot.
If you can't print to 11 x 17, use the 'snap shot' feature in Adobe Reader to split the drawing into two separate 8-1/2 x 11 prints to improve readability.
The first plinth built is the heavy version. The more I thought about it, the more it seemed inevitable that a heavyweight plinth just seems logical.
At this stage, the plinth is complete in its glue-up but still requires much sanding before finish coating can begin. The purpose for this session is to check for fit of the sp10 mkII motor unit within the plinth, and also to fit the tonearm board , then layout for the drilled hole locations to mount the tonearm.
Laying out the tonearm location.
The pivot to spindle distance for the Zeta tonearm is 210.6mm. ( 8.2913 inches) Using the Clearaudio protractor, 210.6 is set on the scale and a 210.6 mm radius arc is scribed across the tonearm board. Anywhere on this arc will correctly set pivot to spindle distance. But we also need to consider a more optimal location of the arm relative to the rest of the turntable. In this case, because the SP10 mkII is a really large TT that was designed for a 10 inch effective length tonearm (as opposed to the 9 inch effective length of this Zeta) there isn't very much room to fit the tonearm without its mounting flange touching the side of the SP10 mkII chassis. As it turns out, there is just enough room to accommodate the Zeta and its 2.375 "dia mounting flange.
The one good thing about the Clearaudio protractor....it works as a layout tool for custom tonearm mounting. Very well, actually. I bought mine when they were new and could be had for approx. $150 usd. Now they cost more and I wouldn't for the price they ask.
Look close and you can see the center punch for the main drill, but also a 2.375 dia is drawn around it in pencil using a drafters compass. This measure insures that all parts of the tonearm will fit the area. Just barely.
Tools in use. A 5/32 inch transfer punch just fits the the Clearaudio tool and serves as both scribe for making the arc, and punch for marking the drilled hole start. The compass lays out for the mounting flange of the Zeta tonearm to allow us to see that it will fit the area. A machinists rule to set the compass diameter.
I can never resist a chance to listen to the rig before everything is done. There's this need to know.
In the above photo one can see the site method as well as the downstream components. I have three Lp spinners using MC cartridges of similar load resistance requirements. They all plug into the 1:10 step up transformer that feeds the multiplied signal into a Wright WPP100C phono preamp, which in turn sends its line level signal to the Classe' CAP 151 integrated stereo amplifier. The processed and amplified signal is then sent to a pair of NHT 2.9 flor standing loud speakers.
Both the SP10 mkII and the Thorens TD124 are using Denon DL-103R low output MC cartridges. Both of these cartridges have been installed into custom exotic wood bodies sold to me by Uwe. The difference however is in the DL-103R mounted to the SP10 mkII. This Denon has been re-tipped at Soundsmith with a Ruby cantilever/Fine-Line diamond stylus. The Denon in the Thorens still uses the stock tubular aluminum cantilever and conical diamond stylus. The Denon in the SP10 mkII uses a Panzerholz body by Uwe. The one in the Thorens uses an Ebony body by Uwe. There are differences in sound quality between these two Denons because of the different cantilever/stylii and also to a lesser extent because of the different exotic wood bodies.
Further notes on early listening.
Just a short note to say that this rig is exceptionally good with The Moody Blues. In fact the turntable is more articulate than I am because I just discovered that I'm not finding the words I need to describe what is working well on these rock records from the psychedelic era. Clean tone. Sharp articulation. Driving rhythm. Deep bass. Clean highs.
Last week I played one side of the Pink Floyd Wish You Were Here album. The side with "Shine On You Crazy Diamond". It had me leaning back in the listening chair , closing my eyes and taking the ride. Sorry. I have no analysis of it to report other to say that I was able to get lost in that music. Good stuff