Test Mule build
Above pic: just prior to mounting the arm. The armboard, which is purpleheart 3/4 inch thick, is drilled for the lower body of the Graham tonearm to fit through, but bolt holes have yet to be placed. I saved the bolt-hole layout for last so that I could place the holes with the SP10 chassis firmly bolted into the plinth. That came next.
Then with the purpleheard armboard marked for the 4 bolt holes, the 4 wood screw fasteners were removed and the armboard taken out to the shop for drilling.
From the back side. Just beneath the purpleheard armboard are two blocks of basswood. They are simply glued down to the multi-ply supports. These basswood blocks have not yet been stained. When I do, I was thinking I'd stain those something odd, like blue.
I chose to leave the finish level in a rough-cut state. Baltic birch multi-ply with a dark brown wood stain (Kona) applied. The hollow chambers within each corner post of this plinth is meant to accept #9 lead shot.
The SP10 stands on heavy slate. I did this to meet the minimum weight requirements of the Minus-K. The slate plinth slabs are from my TD124. At a later date I will build a heavy platform for the SP10 to stand over. And then give the Thorens back its slate
One of the goals for this "Test Mule" plinth was to compensate for that lack of proportion that challenges anyone who attempts to mount a 9-inch tonearm next to one of these players. As is well known, the SP10mkII was designed for 10 inch tonearms. 9 inch arms can be mounted and aligned but they always look wrong.
I chose to make the "footprint" on this plinth compact.
Sound quality is good. This is the first time I've heard the player with the Graham tonearm mounted. And with the Shelter 501-II mc cartridge. It is definitely a level or two better than I heard with the Zeta tonearm. I'm convinced that the Graham definitely "works" on the SP10mkII.
Per plan, today I will listen to this player. I'm enjoying it. It sounds so good I can't believe it is in need of repair. but I know I need to re-cap both the ps and the mainboard beneath the chassis.
Tomorrow I will bring out the test records and record several tracks for analysis. The goal being to establish a base-line reference to be compared to after refurbishment is carried out. More about that in the next installation.
-Steve
Above pic: just prior to mounting the arm. The armboard, which is purpleheart 3/4 inch thick, is drilled for the lower body of the Graham tonearm to fit through, but bolt holes have yet to be placed. I saved the bolt-hole layout for last so that I could place the holes with the SP10 chassis firmly bolted into the plinth. That came next.
Then with the purpleheard armboard marked for the 4 bolt holes, the 4 wood screw fasteners were removed and the armboard taken out to the shop for drilling.
From the back side. Just beneath the purpleheard armboard are two blocks of basswood. They are simply glued down to the multi-ply supports. These basswood blocks have not yet been stained. When I do, I was thinking I'd stain those something odd, like blue.
I chose to leave the finish level in a rough-cut state. Baltic birch multi-ply with a dark brown wood stain (Kona) applied. The hollow chambers within each corner post of this plinth is meant to accept #9 lead shot.
The SP10 stands on heavy slate. I did this to meet the minimum weight requirements of the Minus-K. The slate plinth slabs are from my TD124. At a later date I will build a heavy platform for the SP10 to stand over. And then give the Thorens back its slate
One of the goals for this "Test Mule" plinth was to compensate for that lack of proportion that challenges anyone who attempts to mount a 9-inch tonearm next to one of these players. As is well known, the SP10mkII was designed for 10 inch tonearms. 9 inch arms can be mounted and aligned but they always look wrong.
I chose to make the "footprint" on this plinth compact.
Sound quality is good. This is the first time I've heard the player with the Graham tonearm mounted. And with the Shelter 501-II mc cartridge. It is definitely a level or two better than I heard with the Zeta tonearm. I'm convinced that the Graham definitely "works" on the SP10mkII.
Per plan, today I will listen to this player. I'm enjoying it. It sounds so good I can't believe it is in need of repair. but I know I need to re-cap both the ps and the mainboard beneath the chassis.
Tomorrow I will bring out the test records and record several tracks for analysis. The goal being to establish a base-line reference to be compared to after refurbishment is carried out. More about that in the next installation.
-Steve
Test Mule Measures
I chose three different tracks from a couple of test records to serve as reference points of comparison. Before refurbish. Then test again after refurbish. These below are "before".
The first plot is a 300 hz tone from the hfn 001 test record. The tone is stated to be produced at +12 db. I presume this means plus 12 db over the nominal amplitude, which is not revealed anywhere on the test record outer jack or inner insert.
Next is a Bass Drum hit recorded from the Shure TTR-110 test record. I chose the bass drum track because it presents a sudden tone burst in the lower frequencies.
The third is a silent groove track taken from the HFN 001 test record. I chose the HFN silent track over any of the other silent tracks that exist on other test records because the HFN 001 record was cut on a more modern mastering lathe. So these "silent grooves" should be more silent than those from the older test records. Hopefully my logic holds true.
The method for obtaining these spectrum plots:
1) play the above noted test record on the SP10 mkII as it stands within the "Test Mule" plinth I have pictured above. And the plinth is standing on massive slate, which stands on a Minus-K .5 hz isolation platform. The tonearm is a Graham 2.2. The cartridge is a Shelter 501-II. Phono cable: Incognito using silver solid core wires and built by Garth Phillippe for me circa 2007. Next in the signal chain is a Beyer Dynamic Step up transformer pair. Then a Hagerman Trumpet phono stage. From the stage the signal passes through more silver wire from Garth* into the rca inputs of an Alesis Masterlink 9600 hard disc recorder.
2)The three record tracks are recorded at 24/96 and then burnt to CD. The CD is taken to my PC where the tracks are displayed in Audacity and then the spectrum plots are made as you see them above.
-Steve
* Garth Phillippe. Incognito phono cables were by him. His method was to build phono cables from clip to plug in a continuous run. He always used high quality wires and connectors. ...and the price was always firmly rooted down to planet Earth. May he rest in peace.
I chose three different tracks from a couple of test records to serve as reference points of comparison. Before refurbish. Then test again after refurbish. These below are "before".
The first plot is a 300 hz tone from the hfn 001 test record. The tone is stated to be produced at +12 db. I presume this means plus 12 db over the nominal amplitude, which is not revealed anywhere on the test record outer jack or inner insert.
Next is a Bass Drum hit recorded from the Shure TTR-110 test record. I chose the bass drum track because it presents a sudden tone burst in the lower frequencies.
The third is a silent groove track taken from the HFN 001 test record. I chose the HFN silent track over any of the other silent tracks that exist on other test records because the HFN 001 record was cut on a more modern mastering lathe. So these "silent grooves" should be more silent than those from the older test records. Hopefully my logic holds true.
The method for obtaining these spectrum plots:
1) play the above noted test record on the SP10 mkII as it stands within the "Test Mule" plinth I have pictured above. And the plinth is standing on massive slate, which stands on a Minus-K .5 hz isolation platform. The tonearm is a Graham 2.2. The cartridge is a Shelter 501-II. Phono cable: Incognito using silver solid core wires and built by Garth Phillippe for me circa 2007. Next in the signal chain is a Beyer Dynamic Step up transformer pair. Then a Hagerman Trumpet phono stage. From the stage the signal passes through more silver wire from Garth* into the rca inputs of an Alesis Masterlink 9600 hard disc recorder.
2)The three record tracks are recorded at 24/96 and then burnt to CD. The CD is taken to my PC where the tracks are displayed in Audacity and then the spectrum plots are made as you see them above.
-Steve
* Garth Phillippe. Incognito phono cables were by him. His method was to build phono cables from clip to plug in a continuous run. He always used high quality wires and connectors. ...and the price was always firmly rooted down to planet Earth. May he rest in peace.
Bearing Maintenance, part 1
Following a few days of listening to the sp10mkII, again, in the test mule plinth, I decided it was time to take it back down and get into working through this project. Having recorded some test record tracks of the player prior to any maintenance, we now have a baseline reference of the deck's performance with regard to rumble and wow.
For me the first area to focus on will be the easy part (for me). I want to ensure that the platter bearing is as good as it needs to be. The above photo shows the thrust pad. the dimple at the center of the pad is a wear indicator. Wear is incurred as the platter bearing spins within its bushings and with some considerable downforce applied to a thrust ball. As the hours of operation add up the size of the dimple will increase in diameter and also increase in depth. And we have learned that it is possible to wear completely through the thrust pad.
the optimal condition for the thrust pad and ball, I would think) is for there to be zero dimple at the thrust pad (like new) and zero evidence of wear on the bearing ball.
Thanks to Nils' post earlier, we now know how the thrust cap is attached to the bearing shaft. The cap simply "snaps over" a knob end at the tip of the shaft. To remove the cap I used a pocket knife to separate the plastic cap from the steel shaft. I found that as I gently pressed the knife edge between the cap and shaft, the cap easily lifted off. Then I found this:
There is no evidence of any adhesive being used to retain the thrust cap to the shaft.
And now it appears that there is some 40 year old gunk that has been living inside and in between the cap and shaft. As the cap was removed, a little bit of old lube and debris ran down over the shaft.
Here's a side shot detail of the bearing shaft that shows the shape of the knob end.
Above is a detail shot of the inside shape of the thrust cap. No fancy shapes here.
Tomorrow I'll get some dimensions and post a dimensional sketch of the thrust cap and knob end of the bearing. Then I will look into making a replacement. It might be interesting to try a few different thrust pad materials. The original pad, I suspect, is made from nylon. But I also have a short supply of Torlon and Vespel. (small remnants)
It is also time to do some finish work on the test mule plinth. It needs some clean-up and also it needs 4 more parts to finish its build-up.
-Steve
Following a few days of listening to the sp10mkII, again, in the test mule plinth, I decided it was time to take it back down and get into working through this project. Having recorded some test record tracks of the player prior to any maintenance, we now have a baseline reference of the deck's performance with regard to rumble and wow.
For me the first area to focus on will be the easy part (for me). I want to ensure that the platter bearing is as good as it needs to be. The above photo shows the thrust pad. the dimple at the center of the pad is a wear indicator. Wear is incurred as the platter bearing spins within its bushings and with some considerable downforce applied to a thrust ball. As the hours of operation add up the size of the dimple will increase in diameter and also increase in depth. And we have learned that it is possible to wear completely through the thrust pad.
the optimal condition for the thrust pad and ball, I would think) is for there to be zero dimple at the thrust pad (like new) and zero evidence of wear on the bearing ball.
Thanks to Nils' post earlier, we now know how the thrust cap is attached to the bearing shaft. The cap simply "snaps over" a knob end at the tip of the shaft. To remove the cap I used a pocket knife to separate the plastic cap from the steel shaft. I found that as I gently pressed the knife edge between the cap and shaft, the cap easily lifted off. Then I found this:
There is no evidence of any adhesive being used to retain the thrust cap to the shaft.
And now it appears that there is some 40 year old gunk that has been living inside and in between the cap and shaft. As the cap was removed, a little bit of old lube and debris ran down over the shaft.
Here's a side shot detail of the bearing shaft that shows the shape of the knob end.
Above is a detail shot of the inside shape of the thrust cap. No fancy shapes here.
Tomorrow I'll get some dimensions and post a dimensional sketch of the thrust cap and knob end of the bearing. Then I will look into making a replacement. It might be interesting to try a few different thrust pad materials. The original pad, I suspect, is made from nylon. But I also have a short supply of Torlon and Vespel. (small remnants)
It is also time to do some finish work on the test mule plinth. It needs some clean-up and also it needs 4 more parts to finish its build-up.
-Steve
I'll add those materials to the list. And include a couple of different delrins to consider.
re: Cannondale. circa 1990. 3.0 series alu. color scheme: Chameleon
It has the aluminum front fork as well. I gave it some upgrades after I bought it new in1990. The stock hubs were replaced with Bullsey cartridge bearing types. Shifters were replaced with SunTour above bar types. Brakes were replaced with shimano XT.
The original frame developed a crack at the bottom bracket. At the time I weighed ~220lbs. Perhaps more than Cannondale had bargained for. You could hear a creaky, squeaky noise on each pedal stroke. But the warranty was good and Cannondale replaced the frame with a new one, same style. That one proved to hold up well and is what it is now.
This bike is so damned rigid it has proven to be the most uncomfortable ride I can remember. Oh, one more interesting feature. It has a tire pump that is integrated with the seat post. That part is pretty cool.
-Steve
Bearing Thrust Pad sketch
I took some measurements of both the knob end of the bearing shaft and the oem nylon thrust cap. These are included in the above sketch.
As soon as some materials arrive I will begin making some thrust caps out of an assortment of materials. It might be interesting to run my three test record tracks on each different thrust cap material and report. I'd expect to see some differences between the resulting spectrum plots.
Materials in line so far:
Nylon (nylatron)
Kevlar infused Nylon
Delrin
Teflon infused Delrin
Torlon 4203
Torlon 4301
Vespel
Lignum vitae
Ironwood
The Torlon and Vespel materials I already have. But I will save those materials for last.
-Steve
I took some measurements of both the knob end of the bearing shaft and the oem nylon thrust cap. These are included in the above sketch.
As soon as some materials arrive I will begin making some thrust caps out of an assortment of materials. It might be interesting to run my three test record tracks on each different thrust cap material and report. I'd expect to see some differences between the resulting spectrum plots.
Materials in line so far:
Nylon (nylatron)
Kevlar infused Nylon
Delrin
Teflon infused Delrin
Torlon 4203
Torlon 4301
Vespel
Lignum vitae
Ironwood
The Torlon and Vespel materials I already have. But I will save those materials for last.
-Steve
Wow Steve, I am impressed by your approach to investigate and document the improvements as you go along!
I just opened up my SP-10 bearing to check how my new thrust cap is doing after a week in operation. I guess it is really too short time to say something definite, but any major issues would show up.
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Well, the thrust cap seems to be doing alright. No markings on the cap or axle and the oil looks clean.
I have now added som extra oil (and wiped off the excess) and the bearing is now settling as I write.
I can check what the price would be to make a small batch of these caps, but I am also keen to see what Steve comes up with.
I will now concentrate on updating my old plinth, and also getting an armboard for my old Moerch arm, which now has a 12 inch armwand waiting to be mounted!
Nils
I just opened up my SP-10 bearing to check how my new thrust cap is doing after a week in operation. I guess it is really too short time to say something definite, but any major issues would show up.
Well, the thrust cap seems to be doing alright. No markings on the cap or axle and the oil looks clean.
I have now added som extra oil (and wiped off the excess) and the bearing is now settling as I write.
I can check what the price would be to make a small batch of these caps, but I am also keen to see what Steve comes up with.
I will now concentrate on updating my old plinth, and also getting an armboard for my old Moerch arm, which now has a 12 inch armwand waiting to be mounted!
Nils
[/IMG]
Well, the thrust cap seems to be doing alright. No markings on the cap or axle and the oil looks clean.
I have now added som extra oil (and wiped off the excess) and the bearing is now settling as I write.
I can check what the price would be to make a small batch of these caps, but I am also keen to see what Steve comes up with.
I will now concentrate on updating my old plinth, and also getting an armboard for my old Moerch arm, which now has a 12 inch armwand waiting to be mounted!
Nils
Good input Nils. If there is no evidence of a dimple at 1 week, then the Delrin material must be hard enough for this 7 lb platter.
re: plinth and Moerch arm. Yeah. The better the arm and cartridge, the closer to audio bliss we get. A 12 inch Moerch seems like a really good place to take it.
I was impressed with what I heard while using a Graham 2.2 / Shelter combo. That experience just makes me want to upgrade the cartridge. If budget would allow (it doesn't) I'd consider something along the lines of a DV DRT model. I suspect a healthy SP10 mkII should take good advantage the higher up the cartridge food chain we move. Only limit: funding.
-Steve
Good input Nils. If there is no evidence of a dimple at 1 week, then the Delrin material must be hard enough for this 7 lb platter.
Only limit: funding.
-Steve
Hi Steve. Very impressive focus on getting the best performing material. I wonder if wear performance, measured vibration performance and subjective performance will simultaneously be attained by one material? Anyway, keep up the great work.
I have four working SP10II and one as a parts donor. A very good friend has three more. I am certain we will be interested in acquiring your ultimate choice of thrust pad. I imagine there are a quite a few followers of this thread similarly interested. Maybe this will help defray some of the research and production costs if your are willing and able to supply. Is this possible?
Bon
Nice work
A picture of a other nice example.
A picture of a other nice example.
An externally hosted image should be here but it was not working when we last tested it.
It might be interesting to see if best wear rate coincides with best SQ. It will take some time to assess wear. Figure 1 week normal use then look at the size of the dimple.
Another item we have yet to discuss; the bearing ball at the bottom of the well. I may try a few different bearing balls as well. But the ball material, and sphericity of the ball, may figure in to the wear rates and SQ.
Available ball materials:
high carbon tool steels with hardness values around RC62 (hard as a metal cutting file).
Tungsten carbide (harder still).
Silicone ceramics (good at vibration damping but perhaps an abrasive quality to its surface, etc.
We just buy these from a convenient online bearing store, like Boca Bearing.
I should have some thrust caps to test within a couple of weeks. Right now I'm waiting on materials and also some shop supplies and tools. When I have something to show I'll post. I'll make some extra thrust caps available if there is any interest after the dust settles. But first, let's see what works the best.
-Steve
Nice work
A picture of a other nice example.
An externally hosted image should be here but it was not working when we last tested it.
Oh yes, that is nice. Both the plinth, and Kuzma 4-point. No expense appears to have been spared there.
I like the style on the plinth. The four large corner bevels compliment it.
-Steve
I've been following this thread with great interest, since I'm in for some thrust caps replacement if and when they are available.
Thanks for your research and contribution...
Ditto. I only recently acquired a nearly mint SL-1000 including EPA-100 with obsidian plinth. This thread gave me the courage to tear the bearing down for a look. It is in very good condition, with just a 2mm wide and perhaps .25mm deep dimple in the thrust pad after 36 years! I wish I looked as good.
No idea how common the practice was of embedding the thrust pad in the spindle. I modified a non-inverted VPI TNT bearing in this way (with a torlon thrust pad attached to the spindle) and replaced the steel ball with a Si3n4 ball. This was further improved by surrounding the ball with a delrin donut(with enough clearance to allow the ball to rotate freely), and adding a second thrust plate underneath the ball. The ball becomes self-centering as dimples form in the thrust plates.
Now for the Technics bearing, a similar approach might be taken by replacing the stock end cap with a fabricated bearing well with a concentric threaded rod to adjust the bottom thrust plate. The threaded rod could be extended downward to drain into a heavy mass(like a Porter plinth), or into an energy dissipating device like a Stillpoint Ultra 5 or Ultra SS. I have five Ultra 5's to do this fifth leg in addition to the corners. The fifth leg from the bearing housing should provide the primary path to drain vibration, and might serve to lessen plinth effects of any kind. Maybe stick with the stock obsidian plinth for tradition sake...
I'm inclined to try a Sapphire thrust plate under the floating ball, and to retain the stock Nylontron thrust plate on top--which already has a small self-centering dimple for the ball. With a free-floating ball inside the bronze bushing, oil will be inclined to flow past the ball, surrounding it with lubrication and filling the entire bearing well below. Assuming that the lower thrust plate has less friction than the upper plate, the Nylontron upper bearing will tend to grip the ball more and cease wearing. Dual thrust plates should also distribute the load and allow platter mass to be increased with impunity.
No idea how common the practice was of embedding the thrust pad in the spindle. I modified a non-inverted VPI TNT bearing in this way (with a torlon thrust pad attached to the spindle) and replaced the steel ball with a Si3n4 ball. This was further improved by surrounding the ball with a delrin donut(with enough clearance to allow the ball to rotate freely), and adding a second thrust plate underneath the ball. The ball becomes self-centering as dimples form in the thrust plates.
Now for the Technics bearing, a similar approach might be taken by replacing the stock end cap with a fabricated bearing well with a concentric threaded rod to adjust the bottom thrust plate. The threaded rod could be extended downward to drain into a heavy mass(like a Porter plinth), or into an energy dissipating device like a Stillpoint Ultra 5 or Ultra SS. I have five Ultra 5's to do this fifth leg in addition to the corners. The fifth leg from the bearing housing should provide the primary path to drain vibration, and might serve to lessen plinth effects of any kind. Maybe stick with the stock obsidian plinth for tradition sake...
I'm inclined to try a Sapphire thrust plate under the floating ball, and to retain the stock Nylontron thrust plate on top--which already has a small self-centering dimple for the ball. With a free-floating ball inside the bronze bushing, oil will be inclined to flow past the ball, surrounding it with lubrication and filling the entire bearing well below. Assuming that the lower thrust plate has less friction than the upper plate, the Nylontron upper bearing will tend to grip the ball more and cease wearing. Dual thrust plates should also distribute the load and allow platter mass to be increased with impunity.
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It has been a while since my last post. My fault. I've been listening to this player and enjoying it quite a lot. SQ is very good. Condition can't be too far off nominal. Not by the sound of it.
Meanwhile, the thrust caps will be a reality within the near future. Before end of this month.
With regard to Dave's post, I intend to keep the bearing stock for this project and will simply ensure that its refurbishment is equal to or better than the original equipment. Nylon or Torlon thrust caps. Which will be preferred?!! I'll measure and publish for both.
Presently I have materials in Torlon 4301 and also another bar of Kevlar-filled Nylon. In the fullness of time I will try some other materials previously discussed.
-Steve
That's a gorgeous looking plinth - love the imagination and craft that's gone into that! Very exciting to hear about your impending experiments with different thrust caps too - will be following those with interest. My thrust cap is in pretty good condition - just a tiny dimple in it, but I do wonder if the thrust cap moves a little (its very easy to rotate it by finger after-all) when the platter spins. Surely that would add a little noise. Perhaps a slightly tighter fit would be of benefit? Though I understand it needs to be easily removable too.
Not as nice as yours, but here's my rather modest plywood plinth, with a veneer of zebrano.
- John
Not as nice as yours, but here's my rather modest plywood plinth, with a veneer of zebrano.
- John
An externally hosted image should be here but it was not working when we last tested it.
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Now I'm ready
I have one newly made Torlon 4301 thrust cap made. I'll produce photos and test results of it tomorrow. For tonight I need to re-establish the test references.
Over time I noticed that my Shelter 501-II was producing some unwanted distortions. It never was a good tracker, but lately there has been some audible evidence of mis-tracking even on fairly tame grooves. I put the Shelter back in its case and mounted this:
A Uwe Panzerholst bodied DL-103R with SS ruby Line contact upgrade. It's not quite in the same league with the Shelter but there seems to be no other choice at the moment. Plus the Denon tracks just fine and should be a better choice for testing.
A somewhat longer view of this test session.
I recorded the same three test record tracks and produced the plot spectrums as pictured below:
A 300 hz test tone at plus 12 db from the HFN 001 test record. compare this to the one done with the Shelter last October.
Bass drum hit (3rd drum hit) off the Shure TTR110 test record.
Silent groove track from the HFN001 test record.
Fwiw, I'm testing with the standard rubber platter mat on every test now and in the future, except lastly when I will record the same tracks while using the new Boston Audio Mat 2 which I acquired this November. The Mat 2 does make an audible difference (for the better) in comparison to the standard rubber mat. But for the sake of repeatable methodology, I'll use the standard mat for all bearing thrust cap tests as I report them here.
Tomorrow, we will see how my first Torlon 4301 thrust cap measures.
-Steve
I have one newly made Torlon 4301 thrust cap made. I'll produce photos and test results of it tomorrow. For tonight I need to re-establish the test references.
Over time I noticed that my Shelter 501-II was producing some unwanted distortions. It never was a good tracker, but lately there has been some audible evidence of mis-tracking even on fairly tame grooves. I put the Shelter back in its case and mounted this:
A Uwe Panzerholst bodied DL-103R with SS ruby Line contact upgrade. It's not quite in the same league with the Shelter but there seems to be no other choice at the moment. Plus the Denon tracks just fine and should be a better choice for testing.
A somewhat longer view of this test session.
I recorded the same three test record tracks and produced the plot spectrums as pictured below:
A 300 hz test tone at plus 12 db from the HFN 001 test record. compare this to the one done with the Shelter last October.
Bass drum hit (3rd drum hit) off the Shure TTR110 test record.
Silent groove track from the HFN001 test record.
Fwiw, I'm testing with the standard rubber platter mat on every test now and in the future, except lastly when I will record the same tracks while using the new Boston Audio Mat 2 which I acquired this November. The Mat 2 does make an audible difference (for the better) in comparison to the standard rubber mat. But for the sake of repeatable methodology, I'll use the standard mat for all bearing thrust cap tests as I report them here.
Tomorrow, we will see how my first Torlon 4301 thrust cap measures.
-Steve
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