The Secret Society of Lathe Trolls

There is some stuff in the AES Disk recording anthology about cutting stylus geometry and the design of such things as the burnishing facets.

Si5751 and friends, 35us turn off time beats any relay. Of course actually getting them at the moment is a whole other question! With the micro getting around its inner loop at audio relevant rates (a few tens of kHz) my approach was quite simple, use the bridge measurement to calculate a rough valu...

I thought the usual way of doing this was to blow the oil out of a sintered bronze bushing and then to run the shaft thru the middle with the air applied to the outside of the bronze sleeve. Basically take an oilite bushing, use hot water, detergent and compressed air to force most of the lube out a...

Back to back switching mosfets with SiLabs isolated drivers my man, the future is now! Mercury displacement contactors are really, really cool technology, but we got better ways to do this today for the sorts of voltages and currents we care about. I have also become a huge fan of the little Vishay ...

I am running a bridged class AB thing built as a bipolar EF triple with a folded cascode input stage, basically done that way so that if/when I add feedback the amp will have negligible impact on phase margin anywhere that matters. It measures flat in frequency and phase out to 125kHz where there is...

Unfortunately 'very wide' bass is a thing in certain genres, and that generally means out of phase. Yea, in an ideal world you get handed material where everything is at worst uncorrelated, but negative correlation does happen, and while it is not an issue at high frequency, it absolutely can be one...

Nothing you do to the amplitude of S has ANY effect on the electrical sum to mono of the LR pair (makes sense because that is the very definition of M!). Ears are more complicated then that, being as angle of arrival has a real impact, because the ear is itself an angle dependent filter, and this va...

900ms is 1/2 a turn, which works for the VMS80 because it has memory that provides the required extra delay for the information about the previously cut material, machines lacking this will likely need 1.8 seconds for 33 as they use the signal being cut as the other input to the computations, so an ...

No advantage to hardware over software except that some people see all Analogue as an advantage in the marketing game.

Be a little careful here, the 2122us time constant in the IRIAA makes the effect on groove amplitude flatten out as you describe, but it does NOT make the effect on the reproduced audio flatten out because it is exactly compensated by the RIAA curve in the reproducer. In terms of the reproduced audi...

Just watch out for the need for an allpass in the M component when doing the second order thing, or it will not sum back together with the right slope, and this actually gets somewhat gnarlier in the case of a shelving design as the phase shift thru the allpass network needs to vary with the shelf s...

Biggest hold up at the moment is that nobody has the plug for the feedback connector actually in stock! Literally there is zero stock out there, and without it I cannot wire the servo pack to the motor. I have tried running it open loop at a few hundred mA three phase sine from a stack of power amps...

Add to that a high enough order that the effect is mostly gone by the time we get up where stereo direction cues start to matter. This IMHO was always the weakness of the first order version of the thing, if it is narrowing things to mostly mono below 80Hz, it is still messing with the stereo width ...

Within the lathe itself it is usually just a combination of the various inter stage coupling caps and their load resistors, maybe a few Hz or so, pretty standard for audio doings. Now the mastering console, that will likely have a switchable HPF, and maybe a switchable lowpass as well), there is lit...

Two cross purposes here...

"Preview offset" on a mastering console is a control for relative level between the preview and cutting audio, but I think the OP was using it in the sense of the time offset between the review and main channel, the required "Preview delay".

Trick is to avoid it pumping, because limiting S will cause the width to vary, but to some extent whatever you do is going to impact the audio, question is what hurts least. The problem I see with dynamic EQ things down in the LF region is that as the gain on the low passed bit of S changes, so does...

are you saying that using an EE has a side effect of (subjectively) reducing the bass impact? If the Bass is out of phase of course it does, that IS rather the point after all. However the EE is classically a first order network so it tends to have an effect way above whatever you have dialled in a...

I cobbled something together in C, that pays attention to the timing of the platter encoder pulses from my platter drive to make the delay track precisely.

A few thousand lines of C (Mainly in the delay lock loop), not too bad.

The thing is a fix for the technical limitations at low frequency, but it does effect the sound obviously, so you only use it if you have to, bit like the acceleration and velocity limiters. These things are necessary because both the lathes and the replay doings have some hard geometric and mechani...

Does the depth gauge reflect what is happening? How about the current in the depth control coil? If you cut a test with the damping test mode engaged does the resulting groove look right both at larger, smaller and at the diameter where the problem exists? If you cut with the depth control disconnec...