Newbie project result = low volume and distortion

[JoelSD]

Hello Throlls!

I am a newbie on this wonderful forum and started cutting/embossing a couple of weeks ago after build my 'machine'. After killing 30 CD's, I finaly got a sound! Pushed it to the limit on pre-amp and power amp, but got a low, low volume and some distortions. I am writing here to share my material that I used and to get some advices from you about it and get some techniques from you to improve it some how, the possible as can. This is totally new for me and my lathe 'maths' and theories are very, very green. I will show you some photos and my setup.

So, the setup chain is...

Digital source (Cubase + digital inverse RIAA curve)

IMG_20220408_133225.jpg

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Source output (Onyx BlackJack)

IMG_20220408_131605.jpg

Q-7 Usb MIXER

IMG_20220408_131619.jpg

Pre-amp Fosi audio p1

IMG_20220408_131653.jpg

Power amp Ibiza AMP300 MKII

IMG_20220408_131542.jpg

IMG_20220408_131555.jpg

Cutterhead (Tweeters 100w + 2 crossovers Peying PY-T59 and 1.6mm of tungsteen needle

IMG_20220408_131255.jpg

IMG_20220408_131246.jpg

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About the material I use:

Numark TT550

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CNC lathe

IMG_20220408_131457.jpg

CNC manual level (for the needle drop)

IMG_20220408_131524.jpg

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Lathe velocity controller + motor microstep:

Heating Lamp

IMG_20220408_131704.jpg

Turtle Wax

IMG_20220408_131725.jpg

So, now I will show you the results that I got.

Original vinyl sample examples:

Pro vinyl sample (RIAA).mp3

Pro vinyl sample (without RIAA).mp3

Cutted CD (Philips) sample examples (I increased the volume about 5/10db from the original):

Cutted sample (RIIA).mp3

Cutted sample (without RIIA).mp3

Some microscope pictures here:

IMG_20220408_142601.jpg

IMG_20220408_142611.jpg

Processing cut video:

VID_20220408_140632.mp4

Well, this is how I tried until now after mudering these innocent CD's. Honestly, getting a sound on this was a big deal for me. I hope get some feed and advices to improve the sound from you fellows!

Cheers!
Joel

[farmersplow]

Hello Joel, your first attempts are great. I just started building something like this a year ago.
What I immediately noticed are the following areas that will probably bring improvement:
1. The embedding needle is very vertical. Give a little more "lag" and the result will be even better.
2. Torque Tube: When the needle is closer to the base of the horn, it is easier for the speaker to cut - and more accurately.
3. Torsion spring: It looks like this is a solid material - it hardly allows any movement. This (soft) spring plate should only hold the torsion bar in position at the rear. So that the rod only moves at the front of the needle.
I assume you don't need a stereo effect for now, that's not possible with this single spring. Still I would suggest a V-spring as this current form of spring does not twist easily.
4. Torsion spring retaining wire is missing: If the torsion bar spring is soft, the bar will be positioned in two dimensions (X,Z), but anterior-posterior (Y) movement is possible. this is prevented by a thin wire which I have not seen in your case.
5. Is the needle really tight and without "wobbling" in the carbon rod? (The slit seems to prevent that?)
6. The funnels (aluminum?) are not centered on the torsion bar.
7. During the recording I also heard a regular rumble. I can't say whether it's the turntable or the stepper motor. Perhaps the transmission is so strong because the cutterhead's suspension is too rigid. Do you have a spring that adjusts the bearing pressure in your construction?

But don't worry, this is just the beginning. After all, you managed to put music on the disc. Music you already recognize. So don't give up and keep going.

Greetings from Austria
Thomas

[JoelSD]

Hello Thomas!

Thank you for your great advices and knowledge, it will help a lot. I agree with you, my cutterhead definetily needed some improvement but I didin't know how to do technicaly.

About the topics:

1. Yes, I will try adjust more the angle of the needle to know the difference on this first cutterhead 'build'.

2. Other thing that I didn't know and it is crucial. So, the needle need to be in the center base between both tweeters to cut accurately. That's make a real sense and I will adjust too.

3 and 4. The torsion spring is steel and it's screwed in cutterhead. About the V-spring your mention, is like this type:

large_recordlathe_073.jpg

large_recordlathe_071.jpg

The wire you mention is like this image below?:

large_recordlathe_011.jpg

I glued a very thin carbon rode (see image below) from the inside the cones to contact the thick carbon rod of the needle.

IMG_20220409_085946.jpg

5. The needle is tight to the rod. Should do some wobbling? or it need to be real tight?

6. Yes, geometrically the cones are misaligned. I need to adjust them. I used a beer can to do the cones, I saw somewhere people using a perfume can. Do you recommend it more or it is fine anyway?

7. I noticed too that rumbling, I don't know if it is the power amp fan, stepper motor or the mixer. But I suspect that it is from the mixer, I tested to cut some low frequencies in both channels (in the mixer EQ) and the rumbling disappeared. Should I need a 31 EQ band? Or just try it in the box and the mixer? You said about the suspension of the cutterhead, actually could be tigh too much and influenced that rumble. It is possible to adjust the tightness on the righ wheel. (the lef one is for leveling).

IMG_20220409_090023.jpg

Well, that was a great advice and I apreciate your time for this project avaliation. I will keep it for sure with enthusiasm.

Best regards Thomas!
Joel

[farmersplow]

Hi Joel,
I see you understand what I mean.

A fixed torsion bar spring does not work at all. V spring is as shown in the picture example.

When it comes to wire, I mean something else. I made a sketch for you (based on one of your picture examples).

2022-04-09 18_12_19-Präsentation1 - PowerPoint.png

With this construction the 3D stable position point remains stable - nevertheless the other end of the torsion bar (where the needle is) can move up and down and left and right. (but not back and forth)

All speaker, cone, drive rod and torsion bar connections must be tight. They must not have any elasticity. Every little movement between the parts is disadvantageous!
In your point 7. I can't see any construction that allows the cutting head to move up and down.

Greetings from Austria
Thomas

[JoelSD]

Hello Thomas!

That sketch you made is very clear about that mecanism you have been explaining. Meanwhile, I found a very lucid video of what you mean, I supose you saw already. Take a look:

https://www.youtube.com/watch?v=s62GfJEr6PI

At the end of the video, he explains exactly what you mean. Is a true enlightment.

About the cutterhead suspension, I made a small video how I drop the needle on the disc:

VID_20220410_075432.mp4

I will fix the cutterhead in the next days, following your advices, and I update new tests soon here.

Many thanks! It has been a true help.

Best regards!
Joel

[farmersplow]

Hi Joel, the video explains the function of the V-spring and the retaining wire very well. (The best video on the net).

In your video I can see the height adjustment of the cutting head very well. However, the spring-loaded suspension is still missing!
Your construction allows precise height adjustment - that's very good. But if the record or turntable has even a slight height difference when turning, then the tracking force of your design changes during the rotation.
Do you know what I mean?
Thomas

[JoelSD]

Hello Thomas!

I think I know what you mean, and yes, this construction has no spring and probably make some changes when is recording. When I built it, I tried to figuring out in my mind how to control the level manually and experiment different weights. Then when the needle is on the disc with the weight I wanted, I lock any moviment of the level with the right wheel to avoid any oscilation and be always stable during the rotation. Meanwhile, I will try first improve the cutterhead and continue to experiment to see if I can get some good changes and share with you here.

And, thank you again. It has been a great help to improve.

Best regards!
Joel

[JoelSD]

Hello Thomas!

I 'rebuilt' the cutterhead with the steps you mention before, I embossed some CD's and the 1khz sine wave for testing the output, but the sound recorded has not changed at all. I think I need to create a new improved cutterhead... Have you any advice of tweeters and other precise material for this improvement?

Thank you!
Best regards
Joel

[farmersplow]

There are really many options for loudspeakers. Very few can say which type is the best, (I can‘t). In any case, it should be a tweeter because it is small and can handle high frequencies well. (Low frequencies anyway are not very much transmitted by IRIAA filters).

A:
I noticed that the Visaton model (BF-32 4Ohm) was often used for the first attempts.
Presumably because it has certain advantages:
Small build
Easy to assemble
Good centering of the membrane
Simply attach the cone (for transfer)
20mm voice coil (fairly good for starters)
Low cost (this is important because the first 3-4 speakers tend to go up in smoke)

Disadvantage:
Low performance

Visaton BF32.jpg

Example:
https://www.amazon.de/VISATON-2243-Breitbandlautsprecher-Zoll-279387/dp/B0811XRVNK/ref=sr_1_1?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=3RJO6EJ6O5HJA&keywords=visaton+bf+32+4+ohm&qid=1651089678&sprefix=visaton+bf+32+4ohm%2Caps%2C94&sr=8-1



B:
In the advanced stage, vibration speakers are often used by the trolls. Probably because after a few attempts (years) one notices that the performance of the small loudspeakers is not enough to cut loud (deep).

Advantages:
28mm voice coil
Stronger magnets
Strong

Disadvantages:
The existing coil centering has to be removed and built through laborious work
As a result, putting on a cone is not easy and requires a lot of work.

vibration speaker 4Ω 25W.jpg

Example:
https://www.amazon.de/dp/B09NBF2KZV/?coliid=I2XN231AGENV4B&colid=3KJXC98D4AAKH&ref_=lv_ov_lig_dp_it&th=1


Basically, the price doesn't matter. - Because the speakers are the lowest cost on this project...

Greetings from Austria
Thomas

[farmersplow]

Addition to the vibration speakers:
High weight and complex assembly equipment is required (no screw connections)

[JoelSD]

My first attempt were tweeters with crossover, Peiying PY-T59. I saw in this forum some people and on youtube too suggesting these pair.



https://www.amazon.co.uk/PY-T59-Peiying-Speakers-tweeter-neodymium/dp/B00XJIL7PM

Do you think they are enough to continue testing?

Best regards!
Joel

[farmersplow]

For the first steps - OK

[JoelSD]

Hey!

I'm back for the project. I am starting to build a new cutterhead...more detailed and accurate than the first one.
About the exciters, what do you think about this one? Or I should stay with the tweeters?

https://www.soundimports.eu/en/dayton-audio-daex30hesf-4.html?id=76847138&gad=1&gclid=CjwKCAiA6byqBhAWEiwAnGCA4C5-wkTkJ_kZFoyftHxexDmrRti_9mXlveYzZAvMiA4YZmEMGo_5lhoCZZcQAvD_BwE

Best regards!
JoelSD

[JoelSD]

Hello Trolls!

Some progression here. I made a new cutterhead and I did some experiment with the embossing technique (or tried it).

Some pictures of the new cutterhead:










I was impressed for the result, this is a raw embossing...I didn't use a corrective EQ, only Riaa.
You can listen here the original and my embossing:

Embossed:

Embossed record.mp3

Original:

Original pressed record.mp3

The sound is very clean without any noise in this part but I have some issue with distortion in some peaks of the music and it sounds 'boxy'. Have you have any tips to correct this?

I used tugsten needle and My Shank disc. Heat between 45/50º and used a lot of wax!

I'm very happy to get this modest result because I am the worst being into mechanical / technological stuff and my hands tremble a lot.

Let me know what do you think.

JoelSD

[JoelSD]

Hello!

Updates:

Some new cuts with some EQ experiments.

Second emboss My Shaknk Disc (First EQ).mp3

This one I used some corrective EQ...a little bit better than the first,

Last emboss (My shank Disc) 2nd EQ.mp3

My last one has a better EQ, but I had some issues during the embossing...maybe the needle is a little bit tired.

Let me know what you think.

[JoelSD]

Hey Trolls!

My last cut of today, a little bit better but my needle is dying and I got some noise of course.

Emboss 3 - 28 NOV.mp3

I am using a tungsten needle on My Shank disc, the angle is 60º of the needle...and is with 'cone' format, I will try with triangle to know what I get.I heated the disc between 40 / 45 degrees. I got less noise with 60º!

Well, some improvement to get...but I think it is starting sound something.

[JoelSD]

Hello!

I did some changes in the needle and torque. I got some tips from Nedelcu, I take off the screw in the torque to make the head more lighter. Actually, it worked. I can control better the weight when I touch the needle on the disc. I changed my needle (influenced by EposLab) with a alumminium shank and a diamond tip (triangle) with 100º degree...more or less. (See the pictures)

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My last emboss:

Emboss - Diamond Tip 13 dezembro.mp3

I hope get some tips from you guys, I still have some EQ issues, specialy in mids EQ-

Joel

[JoelSD]

HI Trolls!

My mistake of the last file because was digitalized in MONO.
Stereo one here:

Corte 13 dezembro STEREO.mp3

Joel

[JoelSD]

Hi!

I did my last cut yesterday (Metal track) and I'm very happy with this result. I use a carbon fiber to hold the needle (I am experimenting glue the needle to the torque, it is not the best way...but..) and I start using only diamond tip between 95-100 degree angle. The speaker cones are made by 3d printing, PLA plastic. The volume is not so loud, but not bad at all.

Corte-Omitir-28-Dez-2-Stereo.mp3

Best wishes for the new year 2024!
Joel