Project "Groove Scribe"- A DYI stereo 45/45 head.

[EpicenterBryan]

i am willing to sell a (limited quantity ) set of original neumann sx74/SC99 torque tube with v-spring to experimenters.

Flo,
That's a very generous offer you made to all us experimenters!
That will really help people! The tube is a big stumbling block for many of us.

I can also say the price is very fair too!
Thanks so much from everyone!

Bryan

[Gridlock]

Flo how much for the postcard?

[EpicenterBryan]

Well, it took 4 tries but I actually made a reamer...
As you remember this is a 1:20 taper meaning at the short end it's 1mm, and 20mm up the shaft it should be 2mm. So I started with a 2mm drill bit and here is the end result.

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Hey EpicenterBryan, how the heck did you do that?

Well, first - there is a good reference page here: http://www.magafor.com/841/uk.htm
This shows that for a 1:20 taper, the angle is 2° 52'. That works out to 2.86 degrees.

So I used this gizmo, and set the angle to 2.8 degrees.

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Then I marked the 20mm location on the drill (paint worked better than tape), and chucked it into a hand drill.

Next, I put the angle display under my grinder and aligned one side to be parallel to the left side of the grinding wheel, and the other side (the 2.8 degree angle part) so it was visible. Then turned on the grinder and hand drill and while maintaining the drill bit parallel to the 2.8 degree bar under the grinder I brought the drill bit in contact with the side of the grinding wheel like shown below:

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How close was it? Not too bad...

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I might try it one more time, but I think the overall shape is ok. I really only need a section between 1.2mm and 1.4mm to taper the stylus hole.

Bryan

[Bahndahn]

Nice grind, Bryan! Let us know how that puppy cuts!

I assume, considering you are calling this a 'reamer', that you will pre-drill a hole of the smallest diameter and ream to the larger; this makes this DIY reamer really feasible in that the flutes that are ground away most will be going the least cutting.

If your reamer doesn't work well, it might be worth trying to grind out a simple axially-truncated cone reamer, using some HSS blanks.

Something like this:

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[EpicenterBryan]

I'm not sure if I should call this an update or an info back fill, or if I should just call BS.

Flo offered to sell us experimenters torque tubes about 3 weeks ago, and I chimed in that I wanted one via E-mail. No word from Flo since. I also asked for an update on my order for a Caruso head, now unfilled for over a year (no money exchanged though - I am still inline).

The machinist who is also making one for me finally received the special tapered reamer. But since several people have expressed a desire to have one, he has been working on a jig to stream line making them since there are several machines and tooling changes involved. It's easier to crank out a number of units if tooling is made to facilitate operation changes than it is to make only one by hand the old fashioned way.... One just for me... and I agree.

So here Groove Scribe and I have been waiting patiently. I know the tubes from Flo are correct and if I could get one I could complete the Groove Scribe project and get on with life. I know the machinist is working from measurements made from an actual Neumann part, and it too will be correct and again, I could get on with life.

But I don't have either part. And here we all wait... People get involved in other projects and life is busy... I get that.

Let me say this - Caruso is better than anything I could ever make myself, and better than anything A DIY guy could make as well. I realized this over a year ago and have been on a waiting list to get one ever since (longer than that but I stopped counting).

I messed around with making a torque tube myself a month ago and decided to just buy the correct item from the professionals. I'm happy to pay anyone for the part. For the same part. Buy one from everyone who will make it. Anyone who will ship me one. Try them all eventually, or just use one and shelve the others... Buy more than I need so I to complete the project.

So the question is... Can a guy make the critical part himself? The Torque tube. Like I have discussed before so the cutting angle is correct to compensate for the material spring back? Yes, and no.

I tried making 4 tubes today. The idea was not to actually use them, but to make something I could use to make alignment jigs for the head and spacers for the V springs... Out of 4 attempts I have one usable one for 5 hours worth of messing around.

Here is the front X view with 7 degree angle for the Neumann 320 stylus with tapered hole using my home made 1:20 taper reamer.

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Here is the back end of the toque tube with small hole for piano wire drag link and the larger hollowed out section for mass reduction and glue plug.

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Here is a stylus installed in the tapered hole. This hole needs to be taper drilled deeper. It's nerve racking trying to decide how deep to taper this, especially not knowing if my home made taper is exact enough. Taper it too deep, and the stylus will never snug tighten enough.

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To get a sense of how small this Torque tube is, here it is next to a US Dime.
Now you know... If you have the chance to buy one you should. This is something that is better bought than be home made...

Bryan

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[sakuszi]

Brayan , good job ! But it is only the tip of the iceberg, the biggest problem is the drivers transducters , this is a real problem, without precision mechanical watchmaking, very, very difficult to achieve the quality, speed and power head professional, need a lot of money to invest very much .
[Thanks for the help Brayan ].

[EpicenterBryan]

Brayan , good job ! But it is only the tip of the iceberg, the biggest problem is the drivers transducters ,

Agreed. Although the driver selection may have been flawed from the start, the goal here in my opinion is to learn why they didn't work well and document changes that improve performance along the way. Everything learned can be applied to other drivers. Right now, I just want to complete the head with the final changes so I can see / hear if the channel separation can be improved. That comes down to two final changes:

The changes include the X spring on each driver push rod to insure the driver can only operate at a 45 degree angle. And also the new torque tube that is shorter, with a smaller distance for the tip of the stylus to the center of swing on the tube. Those combined with the head and stylus angle changes dictate the effective vertical modulation angle which will ultimately define the channel separation....The end goal is to play back the groove with a stylus mounted in a phono cartridge at a common playback VTA.

So although the drivers, feedback magnetic isolation and other factors may cripple the frequency response accuracy in Groove Scribe as it is... If we hear (and see) significant increase in channel separation we all know we are on the right track with these most recent changes. I for one want to know for sure if both changes make that happen.

Bryan

[Snug Music]

wohooo...

Hi Bryan, maybe as short info! I had originally made at my hubcaps-cutting head, the holder for the diamond of nylon (small and very light!). recently, I have this mount replaced by brass ala 'souri. to my surprise I discovered that the heights have increased by almost 50 percent. after I corrected the equalizer settings, I had a crazy sound volume. I did not think so ras minimal changes, as dramatic!

Best regards
Scotty

[Snug Music]

To get a sense of how small this Torque tube is, here it is next to a US Dime.
Now you know... If you have the chance to buy one you should. This is something that is better bought than be home made...

Bryan

woww...

17.91 mm diameter!which is really small!!!

that's already in the field of Micro mechanics!

[EpicenterBryan]

An update at last!

I got the torque tube from the machinist, and a prototype of a V-Spring for fit checking. The prototype V-spring is thicker material than the final one will be but since the material hadn't arrived yet, he went ahead and made me this prototype. The final V-springs should be done in another week.

But the good news is that he made 10 extra torque tubes which are available now if anyone is interested.

The prototype V-spring is really cool. It has a spring clip like feature so it kind of clamps on the torque tube but you can still pull the tube in or out and twist it until you are ready to hit the interface with glue.

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The torque tube is very well machined, unlike my home made attempts. This one doesn't have a straight X pattern at the end like my home made one. Eventually, I was going to drill the end of my X pattern to account for the bend radius of the connection links which was not ideal. There would be a void in the center where part of the wire links were not supported. In the version the machinist made, he accounted for both the outside radius and inside radius of the links as they would be bent at a 90 degree angle. So in this photo, you see curved paths for the link wires like they would actually be made from round stock and the link connection to the end of the tube is continuous along the full path. Professionally thought out.

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Today, I've been using these parts for final fit check and working on an adapter / spacer so I don't have to start over. Here is a CAD sot of what the V-spring adapter / spacer looks like. This has a void where the V-spring / torque tube can move without hitting anything. It also has a place where the drag link can be clamped. It also has voids on the sides where feedback wires can exit the head to connect at the DB15 connector at top. And it also has additional clearance to avoid the X spring adapters / magnet mounts. WTF? This is starting to look like a plastic head with an aluminum frame!

Back plate adapter.jpg

Here is the current ABS version of the fit check adapter part.
Next, I'm going to try to print this part in Nylon.

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Wish me luck...

Bryan

[EpicenterBryan]

I have a new found respect for both Todd and Flow.
Wow, messing with connecting rod links is delicate especially with a Neumann style Torque Tube.

So here is a fit check of links to the Torque tube. Those are 0.5mm Phosphor Bronze rods, soldered into short segments of 2mm OD, 1mm ID brass tubes. Those fit inside the 3mm OD, 2mm ID aluminum rods that have the feedback coils wound on them.

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I'm starting to make a batch of components so I can inspect with a microscope and use the best and most consistent parts. Also shown are two soldered parts that are not the same length. But they were useful in trying to figure out how best to align the center rod in the tube for soldering. The 0.020" (0.5mm) Phosphor Bronze rods can be purchased from "Tichy Train Group" here: https://www.tichytraingroup.com/Shop/tabid/91/ProductID/778/Default.aspx. This also happens to be the same diameter used in the drag link on this torque Tube.

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One important thing is to make these identically. So I started working on a jig to hold the parts so I could solder them. I only had one drill bit that is 0.5mm and I broke it ... the next size up was too sloppy. But the idea is like shown below. This a chunk of aluminum with a 2mm hole drilled about 3mm deep to hold the part that the push rod solders into. Then at the center of that hole, is a deeper 0.5mm hole. The idea is to insert a short 5mm long section of 2mm OD, 1mm ID brass tube into the hole, then insert a pre-bent 90 degree segment of 0.5mm Phosphor Bronze rod into the small hole. This way, the rod stays centered to the tube so they can be soldered together. Then the excess on the back side of the tube can be cut away.

Still0032.jpg

Details, Details. One never knows how easy (or hard) it is until you try it. Now I get it... Delicate work for a home DIY project but doable.

Bryan

[EpicenterBryan]

A quick update...

The correct thickness spring arrived!
Everything is now glued in place.
In the next few days I have to put connectors on the FB wires and connect them. Then, this weekend we try this puppy out!

Here is the most recent underside photo with everything glued and drying. I also cut away some excess mounting bracket material to make sure everything clears now that it has to tilt 8 degrees forward. I think it clears now. Oh, how I hope it clears!

This is by no means perfect but it's the best I will ever be able to do with what I have to play with - especially these drivers. If I could get anything near 20db of channel separation with this final DIY version I will be thrilled. Let's see...

And bigger as has been shown here, is not always better! The guts are actually very compact.

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[Gridlock]

Hey bryan i have some blanks and one-siders if you need something to cut on. Also i forgot to mention. The black plates from cash n carry make really frizzy swarf and not a easy to sweep hair type dealy so youre gonna need some mad decent suck if you gonna try that out. But they make some rad cuts. Also theyre super thin- duh- so either bump the head down or raise the disc. Cheers

[EpicenterBryan]

Hey bryan i have some blanks and one-siders if you need something to cut on.

That's a kind offer. I may take you up on some one siders, but I'm pretty sure I have enough to get started.

Hey, drop me a PM with your phone number. You and I should get together and do a YouTube video on those "Cash and Carry" black plastic plates. If they work as well as your experience, we should share them with the trolls!

Was Ken able to fix your K8 electronics? Do you need to borrow that tube amp I showed you? Do you want to come hang out and run the camera while I try out the GS head this weekend?

For the rest of the trolls... The head is ready to check FB polarity wiring tomorrow night.

I'm also messing around with a totally new head design as well. This new one is based on the OrtoFon rocking bridge concept. I'll hold off on details until I come up with a new project name and complete the first prototype. If you have any ideas for a project name chime in. I would like to hint to the OrtoFon name origins (The Danish company's name comes from the greek words ortho (or orto), meaning true or correct and phon (or fon) meaning sound, creating Ortofon, meaning true or accurate sound).

Ideas?

Bryan

[EpicenterBryan]

Hey guys,
Groove scribe is back together and here is a cut with all the changes.
Was it worth it? Yes. I'm happy with the stereo separation which was my primary goal on this test tonight...

EDIT - I had posted a test cut to "sound cloud" and it totally sucked when I played it back. It's not at all what the source sounds like. So I need a new way to get 24 bit audio files posted so people can hear them in better quality.

Ideas?

Bryan

[Bahndahn]

Perhaps: https://archive.org/ ?

[Ciuens]

Dropbox

[Snug Music]

yeah..
dropbox is the best way

[EpicenterBryan]

Ok, Box it is.
Here is a link to download or play a preview in lower quality:

https://app.box.com/s/puz0e0aqhujy61zhm22ujnf8qk9oibkk

On a side note - Has anyone run into this?
I pulled out a disc I used 2 months ago and used it for this test too. It was a 14" Apollo Masters. A chunk of it randomly came off. Never see that before. I don't know the age - must be well over a decade old though. The side of the box indicates pilot run?

Bryan

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[markrob]

Hey Bryan,

Great work! I think you nailed it!

Mark