Deep Grooves Mastering - Project Bladerunner

[opcode66]

I performed tests with an oscilloscope today. I fed a copy of my input signal into the osc scope as well as the preamp. I then fed the feedback monitor signal to the other input on the osc scope. I was able to watch resonance disappear and the two signal more and more closely match each other as I dialed up the feedback mix amount. Once the two signals looked identical, I tried running music through the transducer that would always tweak out my dynamic transducers in the past. This track is very heavy in my rf range around 700 hz. With feedback dialed in, this Frank Sinatra song sounded perfect. Clean and clear. I pushed the volume too much and poof went my drive coil. So worth it though!

Once I got those results, I worked dilligently to finish the wiring for the right channel of my Caruso Preamp. It is now completely built out except for the phono pre board which I'll add later. I also expanded the wiring I had for testing cutterheads on my workbench as well as on the Neumann. Now, I have a harting 14 pin male connector with drive and feedback cables ending in 1/4" male connectors for both the bench and the lathe. I additionally have my feedback testbed that I can run a single transducer in as seen in my previous video.

Lastly, I've been printing parts for my 17th full build. Bladerunner 1.H will be the final r&d cutterhead. Feedback enabled. I'm expecting great results!

[opcode66]

Bladerunner 1.G.2
Oscilloscope Feedback Test

Bladerunner 1.H Build

IMG_8081.JPG

IMG_8080.JPG

IMG_8082.JPG

IMG_8068.JPG

[handcut]

Loving the purple

[EpicenterBryan]

Todd,
I’ve been distracted with business related stuff for many days but I did see your 2 videos this weekend.

I’m convinced you are near, or there, on closing the loop on the whole feedback thing. Congrats on that! There are a few things about the Caruso boards that may be throwing you a curve and will explain why you blew a driver and a few things you can not explain. I don’t have much time tonight to go into this but let me set you in a direction to look at and give you some quick explanations:

The Caruso boards are not set up exactly like you might think, and more specifically the feedback monitor output. Remember, these are designed for the actual Caruso head. There is a feedback option on the boards and several notations about what resistors and capacitors should be included or omitted for various applications. Right now, you are in an experimental situation so not all options apply. I’m pretty sure you built the boards totally stock like they connect to a Caruso head.

I too am in experimental mode, so on my boards I added headers where parts can be removed or swapped in or out without soldering or de-soldering stuff. Or I have added headers where parts can be bypassed by adding a jumper without removing them. Also for my situation I have added headers where I can tap into signals where I need on the boards for testing purposes. A good example is right after the feedback pre-amp but prior to the RIAA related stuff in front of the mixer for the feedback signal.

Here is the big issue: There is an automatic boost of 30db in the low end on the Caruso boards if you install all the components as you would for a Caruso. That 30db boost is there on the output no matter if you throw the RIAA switch on or off. The boost goes directly to the output. It’s post “Drive Pot”. So if you have a tap at the “Drive Pot” you don’t see it. If feedback is zero and you look at drive output, there it is. I ran into this many months ago on my Caruso Massimo build.

I don’t like to share E-mails from people, but I know Flo will be OK with me doing this in this situation. It relates to the 30db boost in the LF that you may have missed…
----------------
RIAA takes place in the first stage IC300A both low and high end
Exactly as described in the block schematics.

47nF/68k is the 50 Hz
47nF/7.5k (6.773k) is the 500 Hz
10nF/ 7k5 is the 2122 Hz

So if you measure at the output of IC300B there is the exactly encoded RIAA encoding

IC402 is the mixer and PID controller. With 30dB boost for low frequency. It is all written and explained on vinylike. So if feedback loop is not closed the signals are not following the RIAA curve. So unless you have an exactly identical cutter head model your spice wont work. Or just for the encoder part it should give same results... For non feedback mods you need to bypass the mixer. Make a buffer with IC402
------------------------

The short version Todd, is that you have been monitoring what is going INTO Caruso (a copy of the input signal) and NOT what is going to your head. Your head is getting 30db more boost in the low end than you thought.

Enough for tonight.
Swap your cables around and monitor signals to and from your head. Tap into the output from your feedback directly if you can right after the pre-amp and all will right in the world. Hope this helps. And, please tell me no secrets Todd.

Bryan

[opcode66]

There are a few things about the Caruso boards that may be throwing you a curve and will explain why you blew a driver and a few things you can not explain.

I think you should re-watch the second to last video. https://www.youtube.com/watch?v=hjhGsaz0YXQ at 7:35 I start to explain that the low end needs different compensation. At 7:42 I actually say "I need to do some compensation there that's different than what's in you know the schematic for Caruso which is what I built it for. So, I'm doing it for Flo's head. I should be doing it for my head. So, I'm going to go in there and change the forward compensation a little bit in the drive circuitry." At this point in the video I show the exact portion of the Caruso schematic that has the forward compensation. Text appears on screen that says "Changes will be made to this section". I'm thinking you must have missed that part because, clearly, I'm aware of all of this that follow from your comment....

I don’t have much time tonight to go into this but let me set you in a direction to look at and give you some quick explanations:
The Caruso boards are not set up exactly like you might think, and more specifically the feedback monitor output. Remember, these are designed for the actual Caruso head. There is a feedback option on the boards and several notations about what resistors and capacitors should be included or omitted for various applications. Right now, you are in an experimental situation so not all options apply. I’m pretty sure you built the boards totally stock like they connect to a Caruso head.

I too am in experimental mode, so on my boards I added headers where parts can be removed or swapped in or out without soldering or de-soldering stuff. Or I have added headers where parts can be bypassed by adding a jumper without removing them. Also for my situation I have added headers where I can tap into signals where I need on the boards for testing purposes. A good example is right after the feedback pre-amp but prior to the RIAA related stuff in front of the mixer for the feedback signal.

I built my boards to Flo's specs for Caruso. I figured that would be a good start and I can arrive at proper compensation via the bench tests I"m now running, which I have. I seriously doubt I will need to change the components more than once. I'm going to simulate in Spice the values I think should go in. Then, actually do the swap out. Headers are just not needed for me.

Here is the big issue: There is an automatic boost of 30db in the low end on the Caruso boards if you install all the components as you would for a Caruso. That 30db boost is there on the output no matter if you throw the RIAA switch on or off. The boost goes directly to the output. It’s post “Drive Pot”. So if you have a tap at the “Drive Pot” you don’t see it. If feedback is zero and you look at drive output, there it is. I ran into this many months ago on my Caruso Massimo build.

Watching my previous video to completion should indicate that I already know all of this and much more. Things you haven't mentioned.

I don’t like to share E-mails from people, but I know Flo will be OK with me doing this in this situation. It relates to the 30db boost in the LF that you may have missed…
----------------
RIAA takes place in the first stage IC300A both low and high end
Exactly as described in the block schematics.

47nF/68k is the 50 Hz
47nF/7.5k (6.773k) is the 500 Hz
10nF/ 7k5 is the 2122 Hz

No secret there. This information is on Flo's updated Caruso schematic available here http://www.floka.com/caruso/caruso_preamp_v1_23_latest_parts.pdf See below

Caruso Schematic.png

The short version Todd, is that you have been monitoring what is going INTO Caruso (a copy of the input signal) and NOT what is going to your head. Your head is getting 30db more boost in the low end than you thought.

That is actually not true. I'm just one step further down the chain already than you are. I am past monitoring and scoping the drive output. I am also past getting good feedback signal. I am now on the next step which is actually applying the feedback to the input signal and measuring the resulting feedback. If everything is working as it should, the feedback monitor will match the input. You should be striving to get your input to match your feedback monitor like this.

input and feedback.png

The feedback signal, naturally is a result of drive, and therefore is an indication of drive. What you also aren't seeing is that, at this point, I could switch between drive and feedback and see no difference.

Swap your cables around and monitor signals to and from your head. Tap into the output from your feedback directly if you can right after the pre-amp and all will right in the world.

At this point my friend, they match. So, that won't be very exciting. The bass exaggeration is coming from forward compensation before the drive output. Therefore it will be present in the drive. The feedback I am getting is extremely accurate. It carries that bass boost in the drive. Therefore, you will see it if you monitor either drive or feedback. Once I swap out a couple of components on each board, then all will be right.

Hope this helps. And, please tell me no secrets Todd.

Nothing that wasn't already covered. Also, there are things that you are not seeing. But, always nice to hear from you, sir. I look forward to seeing you get here too! I have and will continue to keep some very critical pieces of data to myself. They were earned through much work, dedication and consideration.

FYI, I burned out my drive coil in a previous feedback transducer because I turned up the drive on my amp too high. As is typically the case, I get results, I get excited, I like to see how far I can push. Since my coils are on plastic, the plastic deforms if they get too hot. Then the system gets jammed up. Sometimes, when I say I burned out a coil, I don't mean I actually shorted or melted the wiring itself. Sorry for not being specific. I avoid this issue on my lath to some extent because I have channels for helium to pass through the cutterhead body and into the transducers. I don't have cooling on my test bench.

This has all come together for me in a seemingly very short period of time. It is entirely due to the fact that I've been working on preliminary aspects of feedback for a year now. I just haven't posted all the details. You can see my first test below from a year ago.Once I had my Caruso preamp built, I could finally tie everything together for real tests. And, everything worked great immediately. Proper planning + proper project management = results.

[opcode66]

Bladerunner 1.H Buildup and Bench Test

In this video I demonstrate running audio through both my dynamic Bladerunner 1.G.2 cutterhead and my Bladerunner 1.H Feedback cutterhead. You will immediately notice a huge difference in clarity and response between the two versions. In addition to a head to head comparison (pun intended) there is an explanation of why I always put the phone on the torque tube in a lot of my videos and what else is useful to do in order to bench test a cutterhead.

Tomorrow I perform test cut with the feedback cutterhead. If all goes as planned, then I am nearly finished with R&D. I will then focus on learning how to machine parts in metal. Then, I start production early 2016. I will have turnkey cutting drive systems available by 2nd quarter 2016. Cutterheads in dynamic and feedback flavors, preamps, ammeter/fuse/stylus heater racks, amplifiers, wiring and diamond cutting styli.

Stay tuned! I will not disappoint!

[Ciuens]

Todd, congratulations for the work, very well done.
Incredible progress that we're all getting.
Listening to the audio of the cutting head without feedback, the voice of Sinatra has a resonance between 700 and 800Hz, correct? Did you have problem of phase shift? The phase change still remains for me the biggest problem so far. I believe that your transducers should not have much problem with that, because the size and mass.
Once again, congratulations Sir

Ciuens

[dimi751]

Yeah i agree fantastic work from todd, alot of time and effort for him to get to this point... its been a rollercoaster bladerunner ride you dont know what to expect from one post to another always an interesting read.

Todd the feedback head does sound nice through your mic on your camera, but like you mentioned a good test will be a cutt a record looking forward too this.

Great work again thanks for your effort to keep this post running and updated thankyou thankyou.


Dimi

[opcode66]

Thank you both

Yes, Sinatra and Bladerunner share the same RF. So, it is good material to test with.

I actually would have had issues in the high end. However, I avoided them mostly before I even applied feedback. I did extensive testing to avoid EMI. That is one of the biggest sources of issues. Also, keeping the electronics tightly packed and simplistic. Not moving the trimmers off the board. As you add lag to feedback, or saturate it with drive EMI, it starts to do the opposite of what you want and therefore secondary resonance. The final touch is how the coil is made.

This head sounds very close to how my SX sounds when running audio through it. Clean. Punchy. I just don't have that metalic ringing sound of the SX because of the all plastic design. But, as you say, we will see what the grooves will prove.

I can tell you that I can apply a lot of pressure with my finger and I don't end up making an acoustic EQ change like would happen in dynamic. This has two consequences: better response across the spectrum on disc and less noise in grooves.

I'm building up a bunch of spare feedback transducers. I'll test on my vms soon.

[opcode66]

Testing with feedback is going well. I've had to address some issues with my torque tube and how the stylus was being applied to disc when hung on my VMS. I needed to fix issues that were restricting vertical movement as well as causing an incorrect angle of application of the stylus to disc. Also, I needed to dampen things better mechanically.

Everything seems really good now. I'm printing the body for Bladerunner 1.I (18th prototype and hopefully the last). All in all I should be getting much more clear sounding dynamic and feedback assisted cuts.

I've come up with a new production name for my cutterhead. I've registered the URL's before telling anyone this time... I told someone what I was planning on for a production name and the URL was registered a couple days later privately. Annoying... But I'm so full of original and captivating ideas that it hardly set things back at all.

Project Bladerunner is now The Mantra Cutterhead

http://mantra.audio
http://audiomantra.net
http://mantracutter.com
http://mantracutterhead.com
http://themantracutterhead.com
http://themantracutter.com

Pre-Order Sign Up
If you are interested in signing up to be one of the first to purchase a Mantra Cutterhead, please use this sign up page on my site. http://www.deepgroovesmastering.com/preorder.aspx

Printing 1.I

12243063_10206739953210272_7749464526203334171_n.jpg

[EpicenterBryan]

Pre-Order Sign Up
If you are interested in signing up to be one of the first to purchase a Mantra Cutterhead, please use this sign up page on my site.

Todd,
You have some serious cajones. I'm not saying that's a bad thing, just stating the obvious.

Bryan

[opcode66]

Why do you say that? I am very close to having a completed design. I've demonstrated that numerous times. I'm not taking money. I'm asking for those who are seriously interested to put their name in the queue. I won't accept a dime before I'm ready to deliver a head that of course will continue to be fully documented. I've already been offered money by several people.

As yet, I'm the only person who is showing every step of the testing cycle with no crafty editing. My videos are not just audio. You see the grooves happen. You hear the results from that disc. There has been nothing left to the imagination the entire time. If folks are on board with my work, why disparage that?

Or, am I misinterpreting this and you are referring to the name Mantra? I was originally going to call it The Obsidian Blade. The tag line would have been "Nothing cuts like Obsidian". Foolishly in conversation with someone, I mentioned that without actually registering the domain name. A couple days later, that url was registered privately. So, I had to change the name and slogan. It is now The Mantra Cutterhead. I registered every variant worth registering including one of the cool new TLD's mantra.audio. The slogan will be something like Mantra - Perfecting the Art of Harmonic Repetition. I think it follows with my intentions, designs and results sublimely.

[dimi751]

I feel like crying this is a sad day goodbye blade runner I'm going to miss u..

I'm going to miss blade runner posts the name blade runner Is cement in my brain which I hear someone
Saying the name blade runner I don't think about the movie, I think about the cutter head ha !

Welcome mantra cutter head to the world !

Dimi

[inspector77]

Wellcome to the Mantra Cutterhead!!!

So, you will sell three models? a dynamic, feedback (3d printed) and full metal build? what prizes +/- for each model?

Congratulation and keep the hard work

[Ciuens]

As yet, I'm the only person who is showing every step of the testing cycle with no crafty editing. My videos are not just audio. You see the grooves happen.

What exactly do you mean by that? Are you implying that everyone is Fake and only your project is real? Hahaha. Anyway, I liked the name.

Ciuens

[opcode66]

No. I am merely indicating my level of documentation. I did not say that anyone's work here was fake, nor did I imply that. And, it is a true statement. I am the only one here detailing the test cutting process to such an extent.

We have as a community seen several people who have posted fake videos of what has clearly been proven to be fake gear. This is known here. There is an entire section with threads devoted to these individuals. Because I intend to sell my work, and these fakers existed, I feel compelled to maintain a high level of documentation. That is all my friend.

Here is the buildup video of Bladerunner 1.I. I have many improvements mostly around the torque tube and body. I forgot to mention in the video why I moved the Helium inlet to the top. It is so I can make the back connector longer. That way, when hung on a VMS suspension, it fits exactly the same footprint as an SX cutterhead. I no longer have to adjust the height of the suspension box when I change out heads! The rest of the changes were concentrated on fixing issues that were causing the stylus to address the disc incorrectly. Additionally, the stylus wasn't in the optimal place on the torque tube. However, it was place where it was so I would have center pin alignment. Now, the body is slimmed by 1.5 mm and the stylus can be moved down the torque tube closer to the linkage while maintaining center pin alignment. This is all detailed in the video. All the lines are looking fantastic now.

[Ciuens]

Nice. Good Job Todd.

Ciuens

[Sillitoe]

Lets hear it!

[opcode66]

Soon. So many projects at the moment. I keep having to split my time. Master lacquers, pre-mastering, MIDIToLatheAutomation improvements and client build, dgm promotions, web site work, new diamond work, etc. I keep juggling...

[opcode66]

Some exciting things happened tonight with Bladerunner 1.I

I captured the best sounding audio I have to date. Then, two things happened: I melted one transducer which then shorted and I broke the piston rod in the second transducer. So, a very spectacular finish to about 8 seconds of great audio.

Rip 1.mp3

I was having a lot of tracking issues with bass. I need to tighten up my springs a little so I don't have so much excursion for the same relative level. I also need to make the push rods more durable so they no longer break easily. Finally, I desperately need to transition to metal parts. Having parts melt and warp from heat in the transducers and having parts snap like the tip of the push rod is just unacceptable at this point.

This is what the head sounds like after the damage occurred. The popping skips are from the excess excursion.

Rip 2.mp3

Here is a longer rip of the beginning. At about 11.5 seconds the left transducers blows. At 21 you can hear the loose rattling broken piston rod causing distortions. Finally, it seems I have a little crosstalk in the current configuration. I chalk that up to improper stylus orientation.

Rip 1_1.mp3