Straight techie tonearm

[RochaCullen]

Having just bought one of these wonders, I've been looking around at the various upgrades available and the arm seems to me to be the place I'd like to start. Problem is I really like the arm. I had it set up properly in a few minutes, which made a change from the R200 I recently reinstated on my TD160.

There have been other threads on this forum about the arm, but I'd like to see if there is anyone out there up to the challenge of constructing a straight armtube plus headshell that does not cost the ludicrous amount being charged for the likes of the funk arm. :scratch:

An integrated armtube and headshell combo, plus a quality rewire and the arm should have a new lease of life.

Come on folks, who's man enough??

[OneyedK]

Too late :doh:

http://www.turntabletech.com/pickup.htm

This is a bit crude, you'd have to twist the cart by a serious amount to get it properly aligned...

Do you really believe a straight armtube is the better option?

[Qwin]

Here is the one I'm on with, post #19:
http://theartofsound.net/forum/showthread.php?t=24615&page=2

Headshell £20 carbon and aluminium tube about £12 for a metre of each plus some glue. :D

You can read more on my website:
http://www.jkwynn.co.uk/TechArm_HTML/TechArm_Thumbs.html

I can't finish and try it, till I have a working deck to run it on. :unfair:

[RochaCullen]

Hey Ken,

Yes it was your post and reading about the funk firm arm that prompted the thread.

I am very very interested in how you get on. And if it works out well I'd be very interested in one myself.

What's holding up the deck it's planned for?

Nathan

[Qwin]

My x-over build, Tannoy concrete cabinet build, battery power Phono project and my main concrete Technics deck are all on going. The later won't accept a standard arm and the deck intended for the arm is in bits and needs a power supply and main PCB/motor plus a platter. I will eventually get round to it becase its a deck i'm building for my girlfriends system. I allready have another two projects in mind so my time is pretty much booked up till next year. :rolleyes:

[RochaCullen]

Busy man, busy man.

Let me encourage you to move testing the arm up your priority list. ;)

[DSJR]

. I had it set up properly in a few minutes, which made a change from the R200 I recently reinstated on my TD160.



The R200 in proper fettle should be an absolute doddle to set up on almost any deck, especially the TD160. What went wrong guv'nor?

[RochaCullen]

My inexperience is what went wrong. Plus my inability to set the anti-skate (perished belt) slightly upset my obsessive compulsive tendencies.

Actually, full credit to the R200, I pulled an Origin Live Rega I had off the TD160 and put the R200 back in place. Result was I sold the OL1 and bought the techie with the proceeds.

There is of course no denying setting vta, tracking force, and anti-skate on the 1210 tone arm can only be described as a pleasure. Currently with my at440mla it's just singing.

Nathan

[RochaCullen]

Here is the one I'm on with, post #19:
http://theartofsound.net/forum/showthread.php?t=24615&page=2

Headshell £20 carbon and aluminium tube about £12 for a metre of each plus some glue. :D

You can read more on my website:
http://www.jkwynn.co.uk/TechArm_HTML/TechArm_Thumbs.html

I can't finish and try it, till I have a working deck to run it on. :unfair:

Hi Ken,

Where did you manage to pick up the roll wrapped carbon fibre tube and the pulltruded tube?

[DaveK]

Hi, on fibre tube
I got mine on ebay - just search for 'carbon fibre tube' - I got mine from here: -

http://www.ebay.co.uk/itm/350799948643?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

and I can highly recommend the seller, very helpful with questions and quick postage, well protected.

Now can I ask a question? Where did Ken source his LV-X Headshell please as buying one of those would help me greatly. BTW I calculated the required angle as 22deg rather than your 23.4deg so I shall recheck my calculations :) .
TIA,
Dave.

[RochaCullen]

Hi, on fibre tube
I got mine on ebay - just search for 'carbon fibre tube' - I got mine from here: -

http://www.ebay.co.uk/itm/350799948643?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

and I can highly recommend the seller, very helpful with questions and quick postage, well protected.

Now can I ask a question? Where did Ken source his LV-X Headshell please as buying one of those would help me greatly. BTW I calculated the required angle as 22deg rather than your 23.4deg so I shall recheck my calculations :) .
TIA,
Dave.

Hey Dave,

If you have 10 inches or so of this spare that you would be willing to post, I can pay you for that.

Regards,

Nathan

[Qwin]

The tube DaveK used is not suitable. Pultruded tubes are extruded in continuous lengths and have ALL the fibres running down the length of the tube. They are too bendy for tone arm use. You need roll wrapped tube where fibres or carbon cloth are wrapped around a mandrill former. They are many times stiffer for equivelent sections. Becuase they are wrapped on a mandrill the internal diameter is very acurate and consistant. Important if you are going to get an aluminium tube forced down it.

Carbon tube on its own is too light and will change the mass of the arm. Also carbon has a "sound" on its own which is not the best. Frank Schroeder has expressed his views on this, he makes some of the best arms at any price. Using an aluminium liner has a better sound and a mass close to the original Technics arm.

I will check where I purchased my parts and get back to you. :)

[Qwin]

Dave - Fell lucky with the new headshell on ebay :eyebrows: Usually second hand headshells/arms for sale.

The carbon tube I used was also ebay from this guy: http://www.ebay.co.uk/itm/1x-Carbon-Fibre-Tube-10-x-8-x-1000mm-CF10-Tubes-14-75-/151049812700?pt=UK_ToysGames_RadioControlled_JN&hash=item232b453adc

The EXTRUDED aluminium tube was from this supplier who will cut/sell very small legths for DIY projects: http://www.clickmetal.co.uk/ :D

[Qwin]

DaveK- missed the bit at the end of your post about offset angles.

The stock Technics arm has an offset of 22deg. but this is only if you use their other parameters. i.e. using their null points and effective length.

If you use Baerwald alignment (My stated intention) and stock IEC values for inner/outer groove radii. You end up with different null points and a slightly longer effective length of 232.8 and an offset of 23.7deg.

If you want to see the difference between the two I have drawn the protractors, overlaid here: http://www.jkwynn.co.uk/Pics/Technics v Baerwald.pdf
This explains why you have to move the cartridge forward and twist it in the headshell if you move to a Baerwald alignment.

[RochaCullen]

The tube DaveK used is not suitable. Pultruded tubes are extruded in continuous lengths and have ALL the fibres running down the length of the tube. They are too bendy for tone arm use. You need roll wrapped tube where fibres or carbon cloth are wrapped around a mandrill former. They are many times stiffer for equivelent sections. Becuase they are wrapped on a mandrill the internal diameter is very acurate and consistant. Important if you are going to get an aluminium tube forced down it.

Carbon tube on its own is too light and will change the mass of the arm. Also carbon has a "sound" on its own which is not the best. Frank Schroeder has expressed his views on this, he makes some of the best arms at any price. Using an aluminium liner has a better sound and a mass close to the original Technics arm.

I will check where I purchased my parts and get back to you. :)

Hi Ken,

I was speaking to someone last night and they said that the combination of aluminum and carbon is not a good idea as it will have corrosive results.

Have you looked into this?

;)

[Qwin]

Nathan - If its good enough for Frank Schroeder its good enough for me. :D
The tubes are glued, plus what is so corrosive about Carbon? or the resin it is encapsulated in? Never heard of a problem.

Commercial arm manufacturers do this, the sonics are better than just Carbon or just Aluminium. I had a discusion with Frank S. about its use. He uses a third liner for ultimate results, which for obvious reasons did not want to elaberate on. But said my combination was a good starting point. I seem to remember he said his lining was Teflon, I may add a layer of liquid rubber at some point but worry about excessive mass. F.S. prefered material is exotic hard woods tempered with oil/wax.

Aluminium seems to react badly to any conductive material due to electrolysis. Maybe thats the basis of the concern?
Just look at how many Carbon arms are attached to alloy bearing yokes etc. It can't be a major issue. ;)

[DaveK]

Hi Ken,
Being me, I began thinking about this with a blank mind - (comes easy at my age ;) ), that is, unencumbered by any previous knowledge on the subject. Any angle at the end of any fixed centre tonearm is bound to be a compromise as it cannot correctly align with every track on the record. My logic says that one arc crossing a series of concentric arcs is going to cross each one at a marginally different angle is it not? In these circumstances my logic says that somewhere near the middle track should be the best compromise angle, perhaps nearer the inner track as (I think) the angular difference will get bigger as the concentric circles (tracks) get smaller. So that is where I calculated my headshell angle and was pleasantly surprised to find myself agreeing with the guys at Technics at 22deg :lol: .
I calculated the total length of tonearm, from pivot to stylus, by drawing tangents at the point on the fist track where a straight line from the pivot strikes it and similar with the last track. I then averaged those two lengths, (pivot to tangent points) and struck another arc of that average length using the pivot as centre again. Where that arc crossed a track slightly inwards of centre I drew another tangent. The angle between that tangent and the straight line to pivot was what I planned to use as the headshell offset angle, surprisingly 22deg. Easy peasy innit unless my thinking is a load of cobblers :lol: - it has been known ;) .
I suppose I could have calculated the innermost and outermost offset angle and taken an average - wonder how different that would be?
All I need to do now is to ensure that the finished tonearm length is the same as I calculate it should be - and make the bloody thing, of course :lol: .
Cheers,
Dave.



DaveK- missed the bit at the end of your post about offset angles.

The stock Technics arm has an offset of 22deg. but this is only if you use their other parameters. i.e. using their null points and effective length.

If you use Baerwald alignment (My stated intention) and stock IEC values for inner/outer groove radii. You end up with different null points and a slightly longer effective length of 232.8 and an offset of 23.7deg.

If you want to see the difference between the two I have drawn the protractors, overlaid here: http://www.jkwynn.co.uk/Pics/Technics v Baerwald.pdf
This explains why you have to move the cartridge forward and twist it in the headshell if you move to a Baerwald alignment.

[Qwin]

Hi Dave, some cleverer folks than us allready did the maths so you just have to follow their lead. What you are doing is basically right if a bit prone to in-accuracy due to measuring rather than calculating but it won't be far off.
If you check the comparison file I linked you can see that there are two points (the null points) at which the stylus is tangent for the one setting. these points are near the begining and end on an LP and between the two the stylus has varying amounts of missalignment.

The offset angle is linked to the effective length to achieve tangency at the two null points.

I pasted a Baerwald protractor on a piece of board and mounted the basic arm (no base or VTA adjuster just the bearing frame) on to the pivit point on the board and assembled the parts dry with just a tight fit. I adjusted the length of the arm until the stylus lined up with the arc on the protractor. This was while the cartridge was in the central position in the headshell slots. I then marked the position of the tube in the bearing stub with some masking tape. So I knew how far to push it in when glueing. Once the arm was in I moved on to fixing the headshell for correct azimuth to be parallel with the platter.