Project "Groove Scribe"- A DYI stereo 45/45 head.

[juba bc]

hey trolls...so maybe https://youtu.be/rBHgP0ovZIU

[Ciuens]

???


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[juba bc]

stimulate the coils using magnets and not the traditional needle ... see what you can do that with L / R well defined

[Snug Music]

Hey cuiens, I've been thinking that you would rather uses the proven ROD system! What I do not understand what the message from Juba BC wants to tell us with neodymium magnets?
So,..how much winding u make at the rods-feedback? 50 turns?
Greeting Scotty

[Snug Music]

Ok, understand .. Juba BC! , So you would have 2 little magnets on the torque tube and attach the intervening Cartrige right? But what in turn means additional weight.

Greetings Scotty

[juba bc]

small magnets may have the same weight of a feedback coil ... or not?

[Snug Music]

Ok .. I have a Micro neodymium magnets found in my old car radio. So, my idea would be if this sticks to the Torquetube, in the middle of Cartrige. What do you think Juba?
Greeting Scotty

[Snug Music]

So so that the micro magnet in the middle before Cartrige fixed moves. Would that bring the desired effect? Ciuens as you think about it. I'm curious.

[Snug Music]

This would be an idea .. Juba BC, ... if only a neo-magnet in front of Cartrige left / right moves ... is my mindset right? Bryan what do you think?

[Ciuens]

use a cartridge without physical contact is not going to work. In the video posted by Juba, he rubs the neodymium magnet in the cartridge body, which in turn is transformed into signal by the internal coils. If you are analyzing a Ortofon stylus playback, you will notice a small magnet at the inner end that fits perfectly between the coils.

Snug,i'm using 75 turns, but I will use thinner wire to bring about more impedance.

Ciuens

[opcode66]

There's a lot of things you can do with the configuration to maximize the interaction between the coil and the magnets. Last picture I saw of Ciunes, there was a single cylindrical magnet being held with a circular end facing the coil. Can I give you some advice?

Typically the cylindrical magnets have poles running through the length of the cylinder. Therefore, the field is running up and down the shaft and radiating out the circular ends and arcing around the body. In your configuration, you have only one pole facing toward the coil. The pole is perpendicular to the coil. The is not very efficient. It is also not the inverse of the transducer system. The configuration is not taking advantage of most of the flux from the fixed magnet. It would be better if the magnet were standing up so its n/s line was following the spiral of the coil.

Now, lets talk about coverage. It would be good to change not only the configuration of the magnet, but, also add a couple more. Surround the coil. In fact, the best scenario is a ring magnet. The coil travels through the hole of the ring.

There are a couple other tricks. But, I'm keep them to myself. This is already giving you all a lot for nothing.

[Ciuens]

Hello Todd, I came to the same conclusion about the magnets neodymium. ordered some ring-shaped. I test using the small neodymium magnet inside the coil and got good results. some progress with their transducer with feedback?


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[opcode66]

I've done preliminary work on Feedback. But, I stopped. I wanted to make sure my transducers had the best response dynamically as possible. No amount of negative feedback will make up for a shortcoming in the actual design of the transducer. If it has no response above 10K, no amount of amplification will get you there.... So, I fixed all the issues in the drive system first. Then, I made sure the rest of the design was working as expected. Channel separation and vertical motion (true stereo) have also been achieved and fully understood. Now, I finish feedback, because the rest of the system is actually worthy of having feedback applied. Not sure why everyone here is rushing to feedback when other fundamentals have not been demonstrated???

[juba bc]

[img]<table%20style="width:auto;"><tr><td><a%20href="https://picasaweb.google.com/lh/photo/XjAsACngOqURU9RL3NDImipSI8E5q070HK1LI6yC95s?feat=embedwebsite"><img%20src="https://lh3.googleusercontent.com/-7J_KHxUkUoI/VhHDlWdW40I/AAAAAAAAPTo/w0cVVQxGAQQ/s400-Ic42/IMG_20151004_123831265.jpg"%20height="400"%20width="300"%20/></a></td></tr><tr><td%20style="font-family:arial,sans-serif;%20font-size:11px;%20text-align:right">De%20<a%20href="https://picasaweb.google.com/117730450039828711854/4DeOutubroDe2015?authuser=0&feat=embedwebsite">4%20de%20outubro%20de%202015</a></td></tr></table>[/img] snug, this is my idea, pick up the vibrations of the 2 rods independently, but I think the other trolls do not agree with it

[juba bc]

I can not post pictures here, excuse me... https://lh3.googleusercontent.com/-7J_KHxUkUoI/VhHDlWdW40I/AAAAAAAAPTo/w0cVVQxGAQQ/s2048-Ic42/IMG_20151004_123831265.jpg

[opcode66]

A lot of carts are magnetically shielded... That is an issue. Adding moving mass is also not a great idea.

[Ciuens]

Todd, I believe that everyone here (including you) are trying to deploy feedback for several reasons. I concluded that feedback is more difficult to achieve than the dynamic cutting head. 10kHz are relatively easy to achieve with the transducers we are using. If you listen my latest cutting tests, will see frequencies in 18kHz loud and clear, true stereo. I was satisfied with the results obtained without feedback, then we go to the next step: The Feedback. hahaha
https://soundcloud.com/ciuens-silva/cuts-23-08-2015
https://vimeo.com/137323139
Now I'm doing the opposite direction. first unable to close the feedback loop, after that build the remainder of the cutting head around the feedback.

Cheers

[opcode66]

See some grooves?

[Ciuens]

See my post
http://www.lathetrolls.com/viewtopic.php?f=15&t=5945

tomorrow i make more images of the grooves using another microscope


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[EpicenterBryan]

Wow, lots of great inputs from everyone the last 2 weeks.
Sorry I’ve been silent. Been working on several other projects I hope to share in new threads soon.

Sounds more middle with distortion! Have made a pic from cut under microscope...

Hey Scotty,
You may have fixed this by now but if not...
Your groove picture looks like you are having too much vertical modulation where the grooves get deep and shallow. It may either be your source material or wiring on your head. Be sure to check polarity of your driver pair. If you put a mono signal into both channels, one driver should pull and the other should push – producing only lateral movement. Try cutting 1KHz Mono only and see what it looks like. If you see only up and down (vertical movement) swap the polarity on only one driver and check again. What you want to see is lateral movement - a nice even right to left swing of the groove. If you don't see that it's a wiring issue. The lateral movement (nice right left swing) is the sum of Left and Right. The wide groove, narrow groove (vertical movement) is the difference between the Right and Left Channel.

This is the signal flow that I am currently using.

Hey Ciuens, you mention "modified" caruso... and you show the EQ going to and from the Caruso board. It's not clear to me where exactly the EQ is connected. If you have not tried this yet, try moving the EQ to right before the amp. Changes you make there will show up as part of the error signal from the feedback and will get summed by Caruso via FB in. So by making EQ changes there you are really injecting phase changes that may help closing the loop. Yes, any EQ change made there effects frequency but in theory that should be corrected by the feedback but only if the phase changes you make are able to get you in the ball park. It's worth a try. The idea came from MarkRob some time back. Also, make sure the EQ you are using is Analog. Digital EQ will introduce time delays that will totally mess things up. I don't know what model you are using but if it has a low cutoff pot and you turn it all the way down, and a high cut and turn it all the way up it will still introduce phase shifts on the low and high even if all your frequency pots are centered. I modified an analog parametric to make that less but it's not 100% gone. It would take some more changes internally. You might want to check how yours works... That could be the source for much of your frustrations. Check the EQ in to out on it's own with a noise source and your software.

I have tested using this configuration, but did not like. the magnetic isolation is very good, but greatly increases the secondary resonance. I returned to the configuration using the coil wound on the push rod

Wow Ciuens,
What is that crazy rod sticking onto the phono cartridge?
Was this before you went with non-magnetic push rods?
The secondary resonance my not actually be the head but the mounting of the phono cartridge picking up head body vibrations which you don't see with your feedback coils.

I'll try to catch up on the others posts in another response...