SP-10 mkII, the next project

[user510]

This is how I layout for drilling custom armboards. A Clearaudio protractor works very handy as a beam trammel specialized for record player work. I've read some negatives about its abilities for setting overhang/zenith on mounting distances other than 222mm. But for drilling armboards, it is a handy tool. I bought mine back in 2003 when they could be had for around $150 usd. Now they cost quite a lot more and I wouldn't for the current price.



Tools in the photo:
5/32 dia. transfer punch...used as both scribe for making the arc and punch for marking the hole start.

Drafter's compass for laying out the Zeta mounting base.

A machinists' rule to set the compass.

The hole is marked. Then, using a drafter's compass, I've drawn a circle the same dia as the mounting flange of the Zeta that will be mounted. this is how I can see that everything will clear.....just barely. That Zeta has a pivot to spindle distance of only 210.6mm. Kinda' short.

The users manual for the Zeta indicates an effective length of 228.6mm. Overhang is 18mm.

We'll see how it appears after the tonearm is in place. Clearly, a 12 inch effective length tonearm would appear more at home on an SP10 mkII than does the average 9 inch arm.

-Steve

[Nanook]

looking through this thread (not because I have a SP10, but am always curious to see what other folks are working on).

Nice plinth. An alternative to leadshot or sand could be crushed glass. It is available in a few different sizes, does not absorb moisture and behaves somewhat like sand. But it is sterile, and pretty easy to find. It is also cheaper than buying sterile sand, and in bulk is much heavier than sand (due I guess to the fact that the particles are smaller than sand). No lead, no sand, and tou're being "green"

[user510]

or, glass shot that is supplied for glass bead blasting. Available in different gage diameters.

As I recall glass shot comes in large bags at relatively affordable pricing.
Plus there is a choice of other shot media apart from glass.

Thinking of the media used for shot peening.

Thanks,

-Steve

[user510]

It works. Plays records and reproduces music.

The one thing that became quite apparent to me during the tonearm fit-up phase of this exercise is that 9 inch tonearms really don't fit the sp-10 mkii chassis. The TT was designed around 10 inch effective length tonearms. The casework of the motor unit extends out beyond the perimeter of the platter, reducing clearance for the tonearm mount. And the platter itself is more than 12.5 inches in diameter. Compare that to any of my Thorens platters which are all just under 12 inches...and the platter itself is the barrier to which the tonearm must clear.

Nonetheless, it all fits and works. My one major concern is that because the tonearm is mounted at approximately 3 O clock relative to the platter, it must rotate further to reach the end of play of the record. This by itself is no problem, but the cue bar barely extends far enough to lift the arm at end of play in this configuration. Kind of scary. The arm tube might/could fall off the cue bar and perhaps damage/kill a stylus or maybe scratch a record.

I'll have to be careful playing this thing for the near term.

Far term, this turntable screams out for a 12 inch tonearm. Its a transcription deck fer cryin' out loud..

-Steve

[brianco]

I also used this TT with a Zeta....NOT easy! Totally agree re 12" arm! Am building a 14" heavy unipivot and also a 12" .... but as this is the fishing season here and the salmon are here in record numbers this project is on hold 'til the end of November!!

My TT is going in a heavy slate/dural sandwich plinth, but ALL electronics are going off board so it is possible to throw away the top plate......this of course makes short arms much easier to fit.

I take it that you have fully researched the Zeta geometry as some of the maker's info is not totally accurate.

[user510]

Originally Posted by brianco

I also used this TT with a Zeta....NOT easy! Totally agree re 12" arm! Am building a 14" heavy unipivot and also a 12" .... but as this is the fishing season here and the salmon are here in record numbers this project is on hold 'til the end of November!!

My TT is going in a heavy slate/dural sandwich plinth, but ALL electronics are going off board so it is possible to throw away the top plate......this of course makes short arms much easier to fit.

I take it that you have fully researched the Zeta geometry as some of the maker's info is not totally accurate.

I've just used the geometry listed in the Zeta user's guide.
But...while looking at the constraints of the mounting arrangement in this application, I was tempted to do some "what if scenarios" using John Elison's spreadsheet.



So I typed in an additional .4 mm in the effective length to see what would happen to the tracking angle error and tracking distortion plot. There was no significant change from the standard values. ( note: the values in the upper left three cells are those that were altered and that altered the plot.)

But I did not need to use any deviation from nominal mounting geometry. I drilled to a 210.6 mm mounting distance.

But right now I'm having daydreams of converting a Zeta into a 12 inch arm. One would simply need to fabricate a longer arm tube, and heavier CW. It looks like the headshell can detach. But those are just daydreams. There are all those rumours of the Zeta being a true can of worms when attempting to dissect it.

-Steve

[user510]

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 transformers (Sowter) that feed 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 amplified signal is then sent to a pair of NHT 2.9 floor 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.

However, there are some dominant similarities between the two Denons. The tonearms housing the two Denons are different, but each has a certain quality level and has been optimized to carry these low compliance MC cartridges by means of head weight tuning. Each arm cart will resonate at approximately 9 hz lateral using the hfnrr test record (hfn 001).

The Thorens uses an Expressimo modified Rega RB250 that has the so-called 'structural mod'. This is composed of a stainless steel end stub to replace the plastic piece of the standard Rega. The counter weight is the Expressimo "heavyweight". More stainless steel drilled off-center to put center mass at about stylus level. It also has a Cardas Cross wire harness installed. All of this adds up to a fairly decent tonearm which sold for about $680 back in the day. I bought it new in 2002.

The SP10 mkII uses the previously mentioned black Zeta which also has a mod. It has been fitted with a wire harness from Incognito. Silver vdH wire, silver clips and the usual Incognito rca plugs...which appear to be of good quality. The story goes that the Incognito harness was installed at a reputable dealer in the UK. Said dealer called in the arm's original designer/builder to install the harness and adjust pivot bearings for the customer who sold me the arm. Nice story, no

Next:
listening impressions.

last night, after getting the TT situated in its place of honor. And after setting up tonearm adjustments using assorted devices like this:


An Arc protractor with geometry specific to the individual tonearm. These I draw in CAD, then print on photo paper using a decent quality ink jet photo printer (Epson R1800)

And after adjusting VTA to the orientation I have found to be best for these Denons... Slightly tipped up in back to account for the 15 degree angle of the cantilever. The Denons are rather old school and reflect their heritage of a design that dates from the early sixties when lathe cutter head geometry also used that 15 degree angle.

I guess it was sometime in the mid sixties when lathe cutter heads started using a 22 degree orientation.

In any case, my ear tells me to tip the Denons slightly tail up to achieve a compromise between the older Lp 15 degree and later Lp 22 degree VTA geometry. It seems to work for me in that I'm comfy with the results. Sound is not too tipped up, but still achieves a full bodied sweet and ambient sounding presentation on the majority of records I listen to.

I guess I'm giving the SP10 mkII the benefit of the doubt by mounting the Zeta to it rather than the modified Rega previously described. The Zeta does outclass the Rega ..... somewhat. Mainly it seems to allow a faster dynamic and with greater micro/macro detail extraction. After my setup, overall character of tone qualities between the two arms is not that different. Both are sweet sounding and mostly what I would call natural. They both sound somewhat organic on the Td124.

Enough with the preliminaries and on to the heart of the matter; early listening impressions.

So last night after getting this rig all prepped and dialed in I finally plopped down into the listening chair and let some music wash over me. Maybe the glass of straight up bourbon, accompanied by Coke Zero on ice as chaser, seemed to help set the mood.

With all of the above behind me I listened to some records I know.


-Steve

[brianco]

@user510,

I am almost certain that the headshell is not detachable. I've looked at my Zeta and it appears to be a solid one piece shell/arm tube assembly. I've also looked at the Mission version - which is slightly lower mass - and it is certainly a one piece assembly....I believe that this solid structure was a selling point for all the arms in this "family" - the other was the even rarer Mission 'Mechanic' - all of which were made by a tool making company in N. London, UK.

I may still have the earlier literature filed in my deep-litter system....I'll have a look and if I do find it, will send you a scan.

[user510]

Originally Posted by brianco

@user510,

I am almost certain that the headshell is not detachable. I've looked at my Zeta and it appears to be a solid one piece shell/arm tube assembly. I've also looked at the Mission version - which is slightly lower mass - and it is certainly a one piece assembly....I believe that this solid structure was a selling point for all the arms in this "family" - the other was the even rarer Mission 'Mechanic' - all of which were made by a tool making company in N. London, UK.

I may still have the earlier literature filed in my deep-litter system....I'll have a look and if I do find it, will send you a scan.

I should have taken a photo when I had the Zeta off the Thorens.
There is a small screw that appears to make a joint between headshell and armtube on a slight diagonal at the inside face of the headshell.

Of course, you are probably right. I'm just looking at the thing and trying to imagine how it goes together/comes apart. Using that kind of appraisal, could be solid, could be a joint. I can't quite tell.

Meantime, I'm listening to it trace grooves on some records I know.

cheers,

-Steve

[a.wayne]

Steve,

In all fairness you need a few more tables for a righteous comparision.. what phono pre-amp are u using ..?