While I was pondering about cable capacitance in general, I eventually arrived at tone arm wiring. Then there was the question, how a tone arm made of FR4 might perform. Lots of options how to route the wires, including multi-layer boards for shielding all the way around. Thinking along that line, how a four-layer board might compare to a classical tone arm (consisting of a metal tube) capacitance-wise, there was another idea. Parts have gotten really small these days, you can even get the successor to everyone's darling, the 2SK170GR, in a SOT-23 package (IF170A from InterFet); so why not put the "head amp" right there at the "head" of the tone arm? Again, lots of options here. You could do a mirrored design, with one channel on the top layer and the other one on the bottom layer, granting lots of space even for multi-stage op amp designs. Or simply use a single JFET stage, like I have shown in my concept image, to somewhat make the cartridge resemble an electret microphone capsule with its FET already on board.
I'm in for a turntable, so I might as well start the DIY route. Any thoughts? Opinions? Anybody ever did something like this and I didn't stumble upon it? Any killer arguments against this? I've seen tone arms built from a stick of wood and magnet wire, so...
I'm in for a turntable, so I might as well start the DIY route. Any thoughts? Opinions? Anybody ever did something like this and I didn't stumble upon it? Any killer arguments against this? I've seen tone arms built from a stick of wood and magnet wire, so...
There are recent examples of PCB tonearms. There is a market for whimsy portable turntables and a niche of this niche are people modifying those turntables with custom tonearms to hold scratch battles. Unbelievable? Yes, but true 😌
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I had the chance to touch one of those, after that you realise the PCB part may be sufficient, but what about the bearing, the gimbal, the anti skate? Will it really make things easy to make a pcb tonearm while you still have to engineer the rest of the device to get a complete tonearm assembly?
A very small designed smd PCB for your head amp might even fit inside a conventional tonearm tube.. That could give a much more professional look and feel compared to a tonearm made of FR-4 board entirely.
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I had the chance to touch one of those, after that you realise the PCB part may be sufficient, but what about the bearing, the gimbal, the anti skate? Will it really make things easy to make a pcb tonearm while you still have to engineer the rest of the device to get a complete tonearm assembly?
A very small designed smd PCB for your head amp might even fit inside a conventional tonearm tube.. That could give a much more professional look and feel compared to a tonearm made of FR-4 board entirely.
Unipivot and a simple falling weight bias. You can get surprisingly good results that way and no lathes or complex tools required to implement.
Okay, thanks for giving me hints what to search for 👍 (I promised myself: not too many new projects for 2023)..
https://www.diyaudio.com/community/threads/my-latest-iteration-of-nanooks-219-tonearm.173861/ might be a good starting point. There are earlier threads as well on this, but it's an easy DIY
Been done, and might as well include the phono preamp circuit on the board (tone arm).
Or, could be 4 layer, with the 2 outer layers dedicated for shielding/ground planes.
Or, could be 4 layer, with the 2 outer layers dedicated for shielding/ground planes.
I built my first from thin wood strips laminated and glued with araldite. Unipivot from a clock bearing and a carefully sharpened nail, bias weight from fishing weight and spare Meccano. Counterweight moulded from more lead fishing weights.
With the ADC Q series cartridge I had I could get it to track all the tracking tests on HFS 75 and it dealt with warped records astonishingly well. Biggest problem was wires, it was impossible to get properly flexible wire in the 1970s.
K.I.S.S. and knowing that a cylinder is the best for rigidity, plus the need of going over 8" for minimizing tracking angle error, I wouldn't ever think of a PCB for the duty. Aluminum and other metals are ( infinitively...) better.
Then the ''calypso'' mentioned above is probably the most feasible way to go. I do have some Easton arrow shafts... 🤔
Now if only you can figure out a way to connect the cartridge to the spearheaded end. C'mon it would look cool. Yes, 'The Robin Hood'.
Then I'd rather make a PCB headshell that looks like a giant broadhead, and rather use the proper arrow tip as the unipivot bearing 😉. And a nice counterweight looking like the feathering, also made of PCB material - now that'd look cool and be worthy of the name!
Just had another idea for the amplifier part. I found a salvaged RIAA preamp board from a Pioneer A-717 in the workshop, had a look at the schematic, and wondered whether I can't simply take one JFET out of the cascoded differential input pair and put it on the headshell? That would certainly be easier than building a whole new buffer stage and then adjust the RIAA stage to suit (without a noise penalty). As far as I can tell, the tonearm wiring should not introduce any problems in that case. The input cap and resistor would have to be adjusted to the now-non-existent wiring capacitance and cartridge requirements of course, but that's the fun part of DIY after all, isn't it?
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I'm bored and waiting for the this year last minute so...
Just my opinion but if you build the preamp on the arm (lets say close to the pickup) you going to have more "wires" running the length of the arm and yes I'm talking about the power supply for the preamp and everybody knows about running low signal wires close to dc power wires and to top it all without insulation just plain copper lines (pcb tracks)
Again just my opinion
Happy new year
Just my opinion but if you build the preamp on the arm (lets say close to the pickup) you going to have more "wires" running the length of the arm and yes I'm talking about the power supply for the preamp and everybody knows about running low signal wires close to dc power wires and to top it all without insulation just plain copper lines (pcb tracks)
Again just my opinion
Happy new year