Hello people, finally I have built my first "prototype" of a stereo cutting head.
I have utilized plexiglas and makrolon for body, because i hadn't the right piece of aluminium with angle of 90 degrees already bent...
Now I must test it about sound, in each case probably I will build a second with speakers most powerful, but are there tweeters with 100-150w of power very little as magnet diameter ( 3-4 cm max... ) ?
Here some photos :
http://albums.photoonweb.com/studiorp/diy_stereo_cutting_head
Thanks to all and happy cuts !
diy first stereo cutting head
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Hello, yes, I have eliminated two diaphragms with many care, then I reduced the weight of head elimiting the originals ferrite magnets; so I have inserted two mini strong neodym magnets ( only about 1 cm of diameter and 2mm of thickness...); in this way all cutting head weight only about 90 grams.
Perhaps the only problem is the stylus holder, because I hadn't a good solution for increase the lateral movement; yes, the teflon threaded bar is a good system ( see Mark cutting head post here ), but for me there are other better systems to experiment.
The coils came from two old Philips speakers.
At max power near the coils there were about 100-110 celsius grade, while on support of magnet about 50 ( measurements done with riaa encoder inserted ).
About tests on discs, when it will be available, for me will be a pleasure post here.
Thanks for compliments.
Perhaps the only problem is the stylus holder, because I hadn't a good solution for increase the lateral movement; yes, the teflon threaded bar is a good system ( see Mark cutting head post here ), but for me there are other better systems to experiment.
The coils came from two old Philips speakers.
At max power near the coils there were about 100-110 celsius grade, while on support of magnet about 50 ( measurements done with riaa encoder inserted ).
About tests on discs, when it will be available, for me will be a pleasure post here.
Thanks for compliments.
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Angus McCarthy
- Posts: 760
- Joined: Mon Aug 23, 2010 6:22 pm
- Location: Bloomsburg, PA, USA
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aussie cutter
- Posts: 67
- Joined: Thu Sep 18, 2008 9:51 pm
wow!
very nice.
Each time I see a DIY head, I get more convinced to try it out
very nice.
Each time I see a DIY head, I get more convinced to try it out
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com
For do work the two coils actually use a Pioneer VSX-7300 amp ( 120w for each channel ); then I can use too a super rare Acrosound Stereo 120 tube amp, but for convenience use the Pioneer, especially because it has protection circuit for each channel.
About lathe, I have decided to buy a Omnitronic dd-4750 ( 3.5 kg/cm of torque, super wonderful turntable ! ) and adapt it with an old lathe mechanic of a Poltz Freres. Unfortunately lathe is work in progress, not ready yet...
Don't worry people, when all setup will be ready, I will post here photos and a video.
Thanks all.
Raffaello.
About lathe, I have decided to buy a Omnitronic dd-4750 ( 3.5 kg/cm of torque, super wonderful turntable ! ) and adapt it with an old lathe mechanic of a Poltz Freres. Unfortunately lathe is work in progress, not ready yet...
Don't worry people, when all setup will be ready, I will post here photos and a video.
Thanks all.
Raffaello.
Re: diy first stereo cutting head
studiorp wrote:Hello people, finally I have built my first "prototype" of a stereo cutting head.
I have utilized plexiglas and makrolon for body, because i hadn't the right piece of aluminium with angle of 90 degrees already bent...
Now I must test it about sound, in each case probably I will build a second with speakers most powerful, but are there tweeters with 100-150w of power very little as magnet diameter ( 3-4 cm max... ) ?
Here some photos :
http://albums.photoonweb.com/studiorp/diy_stereo_cutting_head
Thanks to all and happy cuts !
Hi,
Nice first pass. It will be interesting to see how it performs. That piece of brass near the stylus holder looks to be larger than needed. Whatever you can do to remove mass will work in your favor. Have you tested the system to find its resonance yet?
Mark
Its called moving mass and you want this part of the head as LIGHT as possible
This way it can respond to signals fed rather than any inertia that would be generated/introduced by a signal and get a heavy piece of metal moving
Newtons Law: For every action there is an equal and opposite reaction
Or his second Law
Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).
The acceleration on any cutter head is quite high so the minimum un-sprung weight possible is the aim
Since you are not using any feedback which effectively acts as a spring you want to have this weight to a minimum
Good job all the same for a first effort well done, keep at it and good luck
Cheers
This way it can respond to signals fed rather than any inertia that would be generated/introduced by a signal and get a heavy piece of metal moving
Newtons Law: For every action there is an equal and opposite reaction
Or his second Law
Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).
The acceleration on any cutter head is quite high so the minimum un-sprung weight possible is the aim
Since you are not using any feedback which effectively acts as a spring you want to have this weight to a minimum
Good job all the same for a first effort well done, keep at it and good luck
Cheers
"The Vinyl Truth"
Chris
Chris
Hi,
You want to keep the moving mass a low as possible and the system resonance as high as possible or you will find that too much drive power is needed to cut at usable levels. If you consider the g forces required to move the a mass back and forth high frequencies with the required excursion, you'll quickly see how important this is. Changing the from brass to aluminum and and reducing the size to a small as possible to get the job done will pay big time when you try to test the cutter.
If you have a oscilloscope, a quick way to measure the resonance is to hook one of the drivers up to the scope vertical input and tap the stylus holder with a pen. The driver will act as a microphone and you should be able to see a damped sine wave at the system resonance. You can even estimate the damping (Q) by measuring the decay time. If you can get into the 700-1Khz range and keep the moving mass under 2g, you should be in the ballpark. The professional heads are able to get the mass down to 1g or less with a 1-2Khz resonance (not so easy to do).
Mark
You want to keep the moving mass a low as possible and the system resonance as high as possible or you will find that too much drive power is needed to cut at usable levels. If you consider the g forces required to move the a mass back and forth high frequencies with the required excursion, you'll quickly see how important this is. Changing the from brass to aluminum and and reducing the size to a small as possible to get the job done will pay big time when you try to test the cutter.
If you have a oscilloscope, a quick way to measure the resonance is to hook one of the drivers up to the scope vertical input and tap the stylus holder with a pen. The driver will act as a microphone and you should be able to see a damped sine wave at the system resonance. You can even estimate the damping (Q) by measuring the decay time. If you can get into the 700-1Khz range and keep the moving mass under 2g, you should be in the ballpark. The professional heads are able to get the mass down to 1g or less with a 1-2Khz resonance (not so easy to do).
Mark
looks nice.
hope to hear some sound.
i always love to see DIY heads.
when i did low cost heads. i always used from the shelf loudspeakers but more in the 30-40 W range.
about the main resonance:
you have almost no control over changing res. frequency.
the only thing is adding or removing weight . but you can not do great change. because spring force is given.
as long as you dont apply feedback you should have the resonance not in the 1 k range.try to shift it up.or try to damp it out with ferrofluid.
with such a construction you will have a roll of at 7-10 kHz.
so if you can move it up there would be great
hope to hear some sound.
i always love to see DIY heads.
when i did low cost heads. i always used from the shelf loudspeakers but more in the 30-40 W range.
about the main resonance:
you have almost no control over changing res. frequency.
the only thing is adding or removing weight . but you can not do great change. because spring force is given.
as long as you dont apply feedback you should have the resonance not in the 1 k range.try to shift it up.or try to damp it out with ferrofluid.
with such a construction you will have a roll of at 7-10 kHz.
so if you can move it up there would be great
About add weight, I had already prepared this eventual solution with two other magnets placing it on top of those already existing ; in this way the total weight goes from 90 to 230 grams.
I have a question about torque tube: I have seen many Neumann and other pro heads photos, and seems that there are two alu tubes inserted one inside the other, so one is fixed on the body of head, while the other can move receiving the vibrations from coils.
Is that right this my reading, or I am in mistake ?
I have a question about torque tube: I have seen many Neumann and other pro heads photos, and seems that there are two alu tubes inserted one inside the other, so one is fixed on the body of head, while the other can move receiving the vibrations from coils.
Is that right this my reading, or I am in mistake ?