fdegrove said:Hi,
Since you so politely ask:
Obviously as light and rigid as you can possibly make it.
Cheers,
First, the answer shoud be in grams, not your vague guidelines with no direction, useless response. I believe it was Havoc who said 300 grams. What dont you understand about my question, and why do you play your little games, cheers?
What is it about the maximum possible mass that you dont understand FDE? You understand english worse than the Japanese engineers I wrote? I think not. Aren't you Flemish?
Trolling once again, not being helpful. You are obviously wrong as well, because as "light as possible" could put it into a bad resonant frequency. Perhaps this is why Air Tangents is heavier, to go below the bad freqencies. 2-4 is much better than the worst 5-8. And very light tonearm will get to 5-8. It must be either extremely light or heavier. In between makes a bad resonant frequency.
I made it so light that the resonance was around 6 hz, It would encourage record wobble.
Hi,
How can it be given in grams when this has to be viewed within the concept of the entire design.
No, I'm not wrong but like anything else in this world you need to strike the best set of compromises within your design aims.
BTW the ATs are very light once you remove the counterweight. They're made out of magnesium ( the armtube) and titanium ( the slider).
In order to dampen any resonances they're fitted with a damping trough which is filled with silicone oil.
The armtube has additional damping properties by its tapered shape and has a stepped multilayer of heatshrinks to further damp out resonance.
Cheers,
How can it be given in grams when this has to be viewed within the concept of the entire design.
No, I'm not wrong but like anything else in this world you need to strike the best set of compromises within your design aims.
BTW the ATs are very light once you remove the counterweight. They're made out of magnesium ( the armtube) and titanium ( the slider).
In order to dampen any resonances they're fitted with a damping trough which is filled with silicone oil.
The armtube has additional damping properties by its tapered shape and has a stepped multilayer of heatshrinks to further damp out resonance.
Cheers,
I really don't know where this thread is going.
As its a DIY forum the point is surely some practical realisation
of a problem and the most sensible design approach to make
it work as best as possible.
I just don't see that here at all.
People are just arguing about stuff because they are
never going to build it - as they say talk is cheap.
As a DIY forum this is not the place for theorectical ramblings,
the proof of this being the biggest threads here are the most
useless, cable directionality, the sound of mains leads etc.
Is Perfusionist actually going to make a parrallel tracking arm ?
If not this is never going to get anywhere.
sreten.
As its a DIY forum the point is surely some practical realisation
of a problem and the most sensible design approach to make
it work as best as possible.
I just don't see that here at all.
People are just arguing about stuff because they are
never going to build it - as they say talk is cheap.
As a DIY forum this is not the place for theorectical ramblings,
the proof of this being the biggest threads here are the most
useless, cable directionality, the sound of mains leads etc.
Is Perfusionist actually going to make a parrallel tracking arm ?
If not this is never going to get anywhere.
sreten.
Hi,
Well, I wouldn't go that far...
However, I do wish people made more effort preparing their discussion. In that way QQ are more ad rem and don't need any second guessing.
Btw, I don't mean you at all Sreten.
If someone wants to build their own LT then the Poul Ladegaard designs are a good place to start.
Some members have already posted their Ladegaard clones here so I see little point in rehashing that any further.
OTOH, if someone wants to copy a LT such as the AT then I won't contribute for obvious reasons but I don't mind explaining the reasoning behind the design.
Accusing people of trolling isn't go to help though, I have better uses for my time...
Cheers,
Well, I wouldn't go that far...
However, I do wish people made more effort preparing their discussion. In that way QQ are more ad rem and don't need any second guessing.
Btw, I don't mean you at all Sreten.
If someone wants to build their own LT then the Poul Ladegaard designs are a good place to start.
Some members have already posted their Ladegaard clones here so I see little point in rehashing that any further.
OTOH, if someone wants to copy a LT such as the AT then I won't contribute for obvious reasons but I don't mind explaining the reasoning behind the design.
Accusing people of trolling isn't go to help though, I have better uses for my time...
Cheers,
Hello flogypbkk,
While the record cutting lathe sits motionless on the studio floor, its carriage/cutting head assembly does not travel at a preset speed. Instead, the carriage/cutting head travels at a variable speed, governed by the volume levels recorded on the master tape which is feeding the lathe.
Therefore, a tangentially tracking tone arm must travel at the same variable speed.
Sincerely,
Ralf
While the record cutting lathe sits motionless on the studio floor, its carriage/cutting head assembly does not travel at a preset speed. Instead, the carriage/cutting head travels at a variable speed, governed by the volume levels recorded on the master tape which is feeding the lathe.
Therefore, a tangentially tracking tone arm must travel at the same variable speed.
Sincerely,
Ralf
Hi Ralf, If the cutting head which is attached to the lathe would travel towards the spindle in a variable speed the distance between the grooves must be visible varying as well. But looking at grooves their distance stays the same apart from the in/out and quite passages between songs. Therefore I still assume and hope that a tangential tonearm travels at constant speed. Does that sound illogical?
There might be two different movements we are talking about - the one I refer to is the movement of the lathe towards the spindle while cutting the groove. As there is a constant distance between the spiraling groove I assume that the lathe travels at a constant speed while cutting the groove. If that is the case then a tangential tonearm ought travel at the same speed from outside in. Plausible?
Very early lathes used a constant pitch (and also constant basic groove depth) but that is not the way to cut long records at good level (And even these had a manual wheel used to put the spirals and marker bands in).
Classically the tape machine had two sets of replay heads, typically spaced to be exactly 1 revolution of the disk apart.
Signal processing then drove the lead screw at a speed just sufficient to maintain some minimal amount of land, and a the difference component was used to deliberately add low frequency modulation of the depth of cut to suit the amplitude of the difference component. This also sums into the leadscrew speed because the width or the cut is proportional to the depth (Yes, the lathe deliberately creates rumble!).
The lathe 'computer' on the early examples were wonders of analogue memories made from switched cap banks driven by photocells looking at the bottom of the platter, transformers doing the sum and difference and all sorts of funkyness.
By the time the VMS80 arrived this processing had gone digital and could actually allow two grooves where they both curved in the correct way to fit such that at some points during cutting the leadscrew would completely stop for a moment (I don't THINK anyone did a lathe computer that would drive the lead screw backwards to snuggle the grooves better, but all sorts of things were done).
Don't forget also that even without the vari pitch computer, the consoles had switches for adding a high pitch marker band to separate tracks, to temporarily increase pitch to reduce the echo you otherwise get on the cut when a silent groove precede or follows a loud bit, and that the lead out spiral was per RIAA standard cut at a VERY course pitch, then of course you get the lock groove which has no pitch at all....
Your assumption of constant groove pitch is NOT how records typically work.
Classically the tape machine had two sets of replay heads, typically spaced to be exactly 1 revolution of the disk apart.
Signal processing then drove the lead screw at a speed just sufficient to maintain some minimal amount of land, and a the difference component was used to deliberately add low frequency modulation of the depth of cut to suit the amplitude of the difference component. This also sums into the leadscrew speed because the width or the cut is proportional to the depth (Yes, the lathe deliberately creates rumble!).
The lathe 'computer' on the early examples were wonders of analogue memories made from switched cap banks driven by photocells looking at the bottom of the platter, transformers doing the sum and difference and all sorts of funkyness.
By the time the VMS80 arrived this processing had gone digital and could actually allow two grooves where they both curved in the correct way to fit such that at some points during cutting the leadscrew would completely stop for a moment (I don't THINK anyone did a lathe computer that would drive the lead screw backwards to snuggle the grooves better, but all sorts of things were done).
Don't forget also that even without the vari pitch computer, the consoles had switches for adding a high pitch marker band to separate tracks, to temporarily increase pitch to reduce the echo you otherwise get on the cut when a silent groove precede or follows a loud bit, and that the lead out spiral was per RIAA standard cut at a VERY course pitch, then of course you get the lock groove which has no pitch at all....
Your assumption of constant groove pitch is NOT how records typically work.
Nice example.
Even after allowing for the IRIAA LF roll off, the bass still takes about 3 times the area for the same nominal level at 20Hz as is occupied at a kHz, in spite of the velocity being about 20dB higher at 1kHz.
Notice also that that LF section has got sufficient difference component to have forced an increase in groove depth, which in tern impacts pitch because the grooves are just wider (The grove has 45 degree walls).
Even after allowing for the IRIAA LF roll off, the bass still takes about 3 times the area for the same nominal level at 20Hz as is occupied at a kHz, in spite of the velocity being about 20dB higher at 1kHz.
Notice also that that LF section has got sufficient difference component to have forced an increase in groove depth, which in tern impacts pitch because the grooves are just wider (The grove has 45 degree walls).
Modern tangental arms, utilize photo-LED's to sense any horizontal "off angle" differences as the arm moves inward, and adjusts the arm via a servo motor as needed to stay within a fraction of a percent of 90 degrees.
My linear turntable gently and silently "corrects" the rear of the arm every few seconds while playing a record.
Gentlemen, thank you for your truly in depth explanation! Highly appreciated and impressive to learn such details. There is however still one question you most likely could give me an answer to which is - does a tangential tonearm move in a linear speed or in an exponential speed from the rim of the record to the center?
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