DId some more checking stuff.
The notch at 3,4 Khz is way less when I took a spectrum from L and R, not the sum. I guess that means some phase issues????
Perhaps time to EQ both left and right channels seperately.
Below you can see a chart of the cut spectrum vs original spectrum eg -2db means 2db lower volume than the original track.
KNOP lathe DIY build
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Re: KNOP lathe DIY build
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Re: KNOP lathe DIY build
Hi,
If you cut a silent groove and capture the playback spectrum under the same playback conditions, you can determine where your noise floor is sitting.
Mark
If you cut a silent groove and capture the playback spectrum under the same playback conditions, you can determine where your noise floor is sitting.
Mark
Re: KNOP lathe DIY build
Hi mark, i will try that tomorrow when i get some fresh stylii.
While doing volume tests broke the cutterhead, one of the pushrod became decoupled from the torque tube, giving some nasty distortion. Did some extra gluing with epoxy, I hope it will be all good again tomorrow.
So much for experimenting this night.
While doing volume tests broke the cutterhead, one of the pushrod became decoupled from the torque tube, giving some nasty distortion. Did some extra gluing with epoxy, I hope it will be all good again tomorrow.
So much for experimenting this night.
Re: KNOP lathe DIY build
Got the cutterhead back up and running, but now got a 3Db difference in volume between channels. Perhaps I did not glue accurately enough.
http://www.knoprec.be/cut%20record%20v3.wav
http://www.knoprec.be/cut%20record%20v3.wav
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grooveguy
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Re: KNOP lathe DIY build
Sounds darn good to me!
Many test and demo cuts posted here and elsewhere by head-builders use electronic music as a test source. Perhaps it's a copyright issue? Unless it's a common piece, it's hard to compare it with "real life." There are a good number of pop-song tracks that are very challenging, particularly highly-compressed material with vocal sibilants. In developing frequency-selective limiters for containing HF energy in FM broadcasting, I've found Sixpense None the Richer's Kiss Me and the opening vocal of U2's With or Without You pose challenges that make self-intermod and other distortions very easy to hear. Another real challenge is Bjork's Big Time Sensuality. Always use the CD as a source, MP3 downloads are already trashed. The challenges should be the same as cutting at 33-1/3 (which is why a lot of disco singles were 45s). Fairchild's Conax (for 'Constant Acceleration') tried to help, but introduced its own artifacts. Ortofon's PWM-based HF limiter worked well; never looked into what Neumann did.
Many test and demo cuts posted here and elsewhere by head-builders use electronic music as a test source. Perhaps it's a copyright issue? Unless it's a common piece, it's hard to compare it with "real life." There are a good number of pop-song tracks that are very challenging, particularly highly-compressed material with vocal sibilants. In developing frequency-selective limiters for containing HF energy in FM broadcasting, I've found Sixpense None the Richer's Kiss Me and the opening vocal of U2's With or Without You pose challenges that make self-intermod and other distortions very easy to hear. Another real challenge is Bjork's Big Time Sensuality. Always use the CD as a source, MP3 downloads are already trashed. The challenges should be the same as cutting at 33-1/3 (which is why a lot of disco singles were 45s). Fairchild's Conax (for 'Constant Acceleration') tried to help, but introduced its own artifacts. Ortofon's PWM-based HF limiter worked well; never looked into what Neumann did.
Re: KNOP lathe DIY build
I use electronic music in testcuts for the sole reason it is my background in music and I know how it is supposed to sound. I did a lot of testing on the new head, the increase in main resonance did lower the efficiency of the head quite a bit. The 0,5A Fast fuses kept blowing, so I bypassed them. Got a nice volume and sound for a while until after 10 or so records where I blew a coil. The heatsinks on the drivers got quite hot the touch, so at least they did their job:) During the dissassembly of the head I noticed that the connection between the torque tube and the pushrods was far from optimal, there was no glue inside the holes in the torque tube. That might explain some of the extra resonances. I will rebuild the head tomorrow.
Re: KNOP lathe DIY build
Does anybody have any experience with soldering the pushrods to the torque tube? Good idea or not?
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grooveguy
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Re: KNOP lathe DIY build
That explains the music choice... understood. Your experience with efficiency dropping with inverse proportion to how good is sounds is par for the course, I guess. The old Presto 1D was a remarkable head and would cut wide-groove 78s with only a couple of watts and flat as a pancake without feedback. Something to be said for 'moving iron' vs. 'moving coil,' perhaps. Sounds like you need 'helium cooling' or some other way to draw the heat away from those coils. Does anyone use FerroFluid for that, or is that just asking for more trouble?
Soldering makes sense... if you can. I keep a squeeze bottle of SalMet soldering flux for jobs that involve aluminum, or just to ensure a solid joint in situations where the solder doesn't want to flow well. It's been out of production for decades, but was the only flux I ever found that would let you solder to ANY metal. Was introduced to it on my first job at a TV repair shop when I was 12, some 65 years ago. Marvelous stuff. If you can't solder, then JB Weld would be my next recommendation. A friend stripped the spark plug threads in his lawnmower, JB Weld-ed the spark plug in the cylinder head and it's still running.
Do keep us posted, you are making terrific progress!
Soldering makes sense... if you can. I keep a squeeze bottle of SalMet soldering flux for jobs that involve aluminum, or just to ensure a solid joint in situations where the solder doesn't want to flow well. It's been out of production for decades, but was the only flux I ever found that would let you solder to ANY metal. Was introduced to it on my first job at a TV repair shop when I was 12, some 65 years ago. Marvelous stuff. If you can't solder, then JB Weld would be my next recommendation. A friend stripped the spark plug threads in his lawnmower, JB Weld-ed the spark plug in the cylinder head and it's still running.
Do keep us posted, you are making terrific progress!
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petermontg
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Re: KNOP lathe DIY build
If you choose to do it, get yourself some brazing rods. Don't water cool the assembly. Just let it cool naturally. You will be dealing with pretty hi heat so make sure all perishables are removed. And don't forget using a little bevel.KNOP wrote:Does anybody have any experience with soldering the pushrods to the torque tube? Good idea or not?
Peter Montgomery
+353(0)894926271
peter(at)petermontgomerymastering.com
Stereo cutter head wanted. Send email or smoke signals.
+353(0)894926271
peter(at)petermontgomerymastering.com
Stereo cutter head wanted. Send email or smoke signals.
Re: KNOP lathe DIY build
Hi,grooveguy wrote:That explains the music choice... understood. Your experience with efficiency dropping with inverse proportion to how good is sounds is par for the course, I guess. The old Presto 1D was a remarkable head and would cut wide-groove 78s with only a couple of watts and flat as a pancake without feedback. Something to be said for 'moving iron' vs. 'moving coil,' perhaps. Sounds like you need 'helium cooling' or some other way to draw the heat away from those coils. Does anyone use FerroFluid for that, or is that just asking for more trouble?
Soldering makes sense... if you can. I keep a squeeze bottle of SalMet soldering flux for jobs that involve aluminum, or just to ensure a solid joint in situations where the solder doesn't want to flow well. It's been out of production for decades, but was the only flux I ever found that would let you solder to ANY metal. Was introduced to it on my first job at a TV repair shop when I was 12, some 65 years ago. Marvelous stuff. If you can't solder, then JB Weld would be my next recommendation. A friend stripped the spark plug threads in his lawnmower, JB Weld-ed the spark plug in the cylinder head and it's still running.
Do keep us posted, you are making terrific progress!
Few years ago, I did some work on using Ferrofluid to improve power handling on my DIY head. Here is the app note I used to make my measurements along with the results.
You can see that the effect was pretty significant. The thermal resistance was cut in half (25C/Watt down to 13C/Watt) and the measured coil temperature dropped from 103C to 55C.
Mark
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grooveguy
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Re: KNOP lathe DIY build
Good work, Mark! I suppose it takes all that math to know exactly where you stand, with regard to the thermal figures, but it's probably pretty apparent that the fluid definitely helps. Any negative side effects?
Re: KNOP lathe DIY build
Hi,
Not that I could see. In fact, the fluid adds a bit of damping. For some drivers it might be tricky to add after the fact. In my case it was easy.
Mark
Not that I could see. In fact, the fluid adds a bit of damping. For some drivers it might be tricky to add after the fact. In my case it was easy.
Mark
Re: KNOP lathe DIY build
I checked on the visaton drivers but there is no easy acces to inbetween the coil and the gap to the center. Rebuit the head today, no budget for glue/brazing rods so same glue as before. Added some 40mm fans for some active cooling. Needs some rgb leds to go full casemod style.
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2bitcomputer
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Re: KNOP lathe DIY build
That looks effing great!
I guess I worry the fans will be heard through contact (but I'm sure you've considered that - assuming they're connected to the head somehow) - I guess you could rig another gantry on the same lead screw or belt and have it track along and above your head while blowing down on it ?
I don't know...
Anyways, nice!
I guess I worry the fans will be heard through contact (but I'm sure you've considered that - assuming they're connected to the head somehow) - I guess you could rig another gantry on the same lead screw or belt and have it track along and above your head while blowing down on it ?
I don't know...
Anyways, nice!
Re: KNOP lathe DIY build
About the fans, I'll try it out today. They probably will be heard but who knows?
Re: KNOP lathe DIY build
The fans do not produce noise above the existing noisefloor at 5v. I'll leave them on for now... I will try some volume tests after I get through my current orders....
Re: KNOP lathe DIY build
So I cut about 80 records with the the new cutterhead, the glued connections hold up well.
Things I have learned: for some reason the fabfilter EQ did not match the curve completely, like the 4khz issue peak/dip, the response of the EQ was about 100-200hz off. Manual finetuning did seem to help a lot.
Recalibrating the curve everytime you start on a day cutting also did seem too help.
Got myself a humidifier, as due to the freezing temperatures the air was getting dry and I was getting some nasty statics. Relative humidity went up from low 30s to high 40s in the cutting room. Before I got it after about 6 records I would start to get swarf issues and some nasty distortion on my pickup. I though I ruined a batch of records but it was just static. Now I can cut a whole day long without issues.
I now preheat the records, resulting in a lot less warp. Also helps a lot.
A steep lpf (72db/oct) on 16khz did allow me to cut a lot louder without significant heat buildup. Using the linear phase function of fabfilter I could not hear phase issues in those regions.
The screw next to the cutterhead makes things a lot simpler to set cutterhead downforce accurately. I adjust it so that the needle has about 1mm clearance to the record when the cutterhead is down on the weighting scale.
No need to remove the stylus for a broken one anymore.
Starting tomorrow I will be moving the cutting machine to the new built studio location.More space, way less background(road) noise, proper monitoring and room treatment. Very excited.
.
Things I have learned: for some reason the fabfilter EQ did not match the curve completely, like the 4khz issue peak/dip, the response of the EQ was about 100-200hz off. Manual finetuning did seem to help a lot.
Recalibrating the curve everytime you start on a day cutting also did seem too help.
Got myself a humidifier, as due to the freezing temperatures the air was getting dry and I was getting some nasty statics. Relative humidity went up from low 30s to high 40s in the cutting room. Before I got it after about 6 records I would start to get swarf issues and some nasty distortion on my pickup. I though I ruined a batch of records but it was just static. Now I can cut a whole day long without issues.
I now preheat the records, resulting in a lot less warp. Also helps a lot.
A steep lpf (72db/oct) on 16khz did allow me to cut a lot louder without significant heat buildup. Using the linear phase function of fabfilter I could not hear phase issues in those regions.
The screw next to the cutterhead makes things a lot simpler to set cutterhead downforce accurately. I adjust it so that the needle has about 1mm clearance to the record when the cutterhead is down on the weighting scale.
No need to remove the stylus for a broken one anymore.
Starting tomorrow I will be moving the cutting machine to the new built studio location.More space, way less background(road) noise, proper monitoring and room treatment. Very excited.
.
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grooveguy
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Re: KNOP lathe DIY build
Your excitement is contagious! Please continue to keep us informed; you are making great strides.
Re: KNOP lathe DIY build
Hello everyone!
First of all best wishes for the new year. May it be a year of good health and lots of record cutting for all of you.
I moved the lathe to my new studio and made a few upgrades. The lathe is now wall mounted with suspension blocks beneath. Redid the vacuum housing, its a lot smaller but even more silent. Made a new stepper motor mount with its own suspension and made an armature for the cutterhead fans. Also redid the heating lamp. Added a drawmer 3 band compressor to the chain, for hf compression. But the best upgrade is the monitors. So much more revealing than my previous setup. Makes troubleshooting cutting issues so much easier. They are acoustic energy ae22's with a parasound amp.
First of all best wishes for the new year. May it be a year of good health and lots of record cutting for all of you.
I moved the lathe to my new studio and made a few upgrades. The lathe is now wall mounted with suspension blocks beneath. Redid the vacuum housing, its a lot smaller but even more silent. Made a new stepper motor mount with its own suspension and made an armature for the cutterhead fans. Also redid the heating lamp. Added a drawmer 3 band compressor to the chain, for hf compression. But the best upgrade is the monitors. So much more revealing than my previous setup. Makes troubleshooting cutting issues so much easier. They are acoustic energy ae22's with a parasound amp.
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grooveguy
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Re: KNOP lathe DIY build
What a cozy place to spend one's days! That really looks nice. I can see why you opted to hang the lathe off the wall, it looks very substantial; you could host a dance party and have nary a groove-skip. Do keep us updated on this, you are indeed our model of success.