Deep Grooves Mastering - Project Bladerunner

[Stevie342000]

It looks promising and it appears to be competitively priced as well. The idea around the slot in drive/feedback coils allows for minimum downtime.

Winding coils may not be an issue but printing heads on a 3D printer will be the time consuming part. Not sure how long it takes but you should be able to produce a completed head a day, which should be high enough for demand.

The only other thing I would ask would be how much would the replacement coils be if you needed a spare once you blew the first one (if that should ever happen - you are supplying a spare set as standard)?

[opcode66]

But by the end of March? Are you crazy?Bryan

This will be my primary project again. I'm really close already.

Todd never sleeps !!! great work!

Not much. No. Lately, I've been doing two to three hours of sleep twice a day.

Winding coils may not be an issue but printing heads on a 3D printer will be the time consuming part. Not sure how long it takes but you should be able to produce a completed head a day, which should be high enough for demand.

The only other thing I would ask would be how much would the replacement coils be if you needed a spare once you blew the first one (if that should ever happen - you are supplying a spare set as standard)?

Winding the drive coils is actually quite tricky. I make it look and sound easy. But, winding flat enameled wire (which I make myself) turn by turn with precision is sort of an artform. Especially multilayer coils. I can do up to a 5 layer coil now. 170 turns, each one straight and aligned. This is very different from other types of coils. Only letting you know what might not have been apparent in the picture above. Thanks for the interest.

With respect to the parts, yes, I can print all the parts in one day for a head. I can get one or two additional printers for a reasonable investment and crank out parts for multiple heads in one day. I can also do various color schemes as per the client's request. Some parts will be produced in metal that are currently plastic. But, to keep costs down, many parts will remain plastic. Once I have parts for a head, I can commence the build the following day. All the while, parts for the next head can be printing.

Each cutterhead will come with two spare transducers (a left and a right). That is four total. If you blow one, in the same day, you can be back up and running with practically zero downtime. No complicated tools or knowledge required. You then order a spare transducer card from me for a very reasonable price. If you are a beginning cutter, why not purchase spare cards with your cutterhead in advance and in addition to the two that will accompany the head? I'm not exactly sure on pricing. But, trust me, it won't be a shocker at all. Quite reasonable.

[Stevie342000]

I know we have not finalised the price one either type of cutter head yet but if you bought a non feedback one, my assumption is that at a later date you could upgrade to the feedback type as the whole system is modular.

Very exciting lots of possible options .....looking forward to hearing more about your developmental stage of the feedback head.

[opcode66]

Thanks. What you are saying is absolutely correct. Though, I likely wouldn't wire a head for feedback if it wasn't going to have feedback coils in the transducers. So, in this case, the head would have to have additional wiring and female socket pins added.

I'm not sure the price will really be that much different between feedback and dynamic to be honest. Maybe $100. Why not get feedback.

[Stevie342000]

Another thought occurs to me (which we may have covered earlier in this thread) but would there not be the opportunity to sell a mono head with or without feedback from the work you have done on the stereo head?

Essentially your head is new develop based on Neumann head? But with a bit of lateral thinking thrown in as to how a similar head could be developed based on X head, so it bears a passing resemblance to the aforementioned but is actually something quite different.

Excellent work given the time frame for the development of this head (6 months all told) whilst working on other areas to pay bills and to develop other projects.

[opcode66]

Again, thank you for the feedback and interest. I've been asked several times about reworking the final design into a mono head. It is still a possibility. However, I think I would do things differently. More like a moving iron design. I really can't fathom how I could use my current moving coil design for lateral without adding some sort of hinge. The real thing to consider is that older mono heads from 70 yeas ago are selling for close to 1K USD. So, for not much more, why not get a modern stereo head?

Technically, I only worked on Bladerunner for 4 months. Nothing significant has been done on the project for the past two months. I've had to prioritize other stuff ahead of Bladerunner. Not anymore though.

[Stevie342000]

Thanks. What you are saying is absolutely correct. Though, I likely wouldn't wire a head for feedback if it wasn't going to have feedback coils in the transducers. So, in this case, the head would have to have additional wiring and female socket pins added.

I'm not sure the price will really be that much different between feedback and dynamic to be honest. Maybe $100. Why not get feedback.

Point taken it was an avenue worth exploring but as I have posted since your last post, what about a mono head with the feedback.

Is there not the option if you do not have the ability to apply feedback that you could leave it disconnected? What sort of effect would this have on overall response?

If I have understood the objective of adding feedback is to make the head response more flat and linear across the audio range (if that is the correct terminology to use).

I suppose I should start saving my pennies and order one soon, once we have a finalised version and a price (assuming I get the job that I am going to an interview for on Monday coming).

At the point you have the finalised version you will of course let us all know either in the process or at the end of the specifications for the head. Being an old school of amplification fan I have my eye on the BBC version of the Presto 88A amplifier and their version of the Presto 41A Limiter (they modified them, it's in the reference section).

[studiorp]

But the definitive version of your head will be all in plastic, or you are thinking to build one in metal ?

[opcode66]

Not all plastic. But, as much as possible. So, the body will be plastic yes. But, not the bobbins that the drive coils are wound onto. Nor the torque tube. These parts will certainly be metal. Various others as well like the springs and vacuum tube.

[opcode66]

You have it correct Steve. The feedback exists to flatten the frequency response and tame the resonant frequency and its higher order harmonics. You can cut with any cutterhead on an open loop (without feedback being used or existing at all). In this scenario, you would likely want to create an EQ curve that would help to reduce the RF of your cutterhead. There are a few ways to go about making such a curve. Generally, you cut some pink noise, rip the cut, analyze it, determine a curve that will flatten the response and apply that to anything you cut. Harbal is a program you can purchase to aid in this analysis and curve generation.

You'll be able to use a Caruso pre-amp with my feedback cutterhead.

Good luck to you for Monday.

Cheers!

[Stevie342000]

You're obviously not sleeping yet today, as out posts are crossing over but I think the syntax is intact.

No problem, if you do not ask questions how are you supposed to learn, a process that should not become stagnant in a persons life.

As for a metal version or part metal version of the head, of course dependent on the metal used it may change the electrical or magnetic properties of the current functioning head needing more work and it would of course be more expensive.

I think it is fine as is and black is such an attractive colour (I am of course being obtuse, as black is not a colour any more than white is). The same as light is both a wave and a particle, in addition to being neither at the same time and the cat is still in the box but is it alive or dead and if you put your hand is it going to scratch you or bite you?

Hey if all the ladies should have a little black number, why can't we be the same.

As for a mono head, yes I see your point about the angle and transference of the energy without a hinge or some kind of pivot. How did Neumann do it or Ortofon for that matter in their mono heads were they not moving coil? Fairchild is another example as is Grampian but I think that one is covered.

How about taking a look at the AR Sugden patents (the mono or the stereo)? I have the stereo patent if you need it and the mono but sure it is in the reference section. What about an RCA replica? Or Olsen or Universal all supposed to be good heads, there must be patents on them even if the heads are thin on the ground in actual samples.

[studiorp]

About old mono heads, as seen in these days, brands as Grampian, Neumann , etc. goes for over 1000$. So, yes create a new mono head for who love the mono sound could be perfect. But for who as me that haven't many money, why not do experiments with a old mono head ? For example I have built a bobbin with two coils inside, each separated and insulated from the other. Now the sound inside my head is with two channels; I don't know if is true stereo; in each case I can check it with a stereo phase correlator.
All is many simple : I had divided the value of original coil ( 22-23 ohm dc ) for 2, so the result is 11-11.5 ohm for channel. The system work, but I must try to cut for hear something and at the moment isn't possible, why I am totally revisiting my lathe project.

[Stevie342000]

You have it correct Steve. The feedback exists to flatten the frequency response and tame the resonant frequency and its higher order harmonics. You can cut with any cutterhead on an open loop (without feedback being used or existing at all). In this scenario, you would likely want to create an EQ curve that would help to reduce the RF of your cutterhead. There are a few ways to go about making such a curve. Generally, you cut some pink noise, rip the cut, analyze it, determine a curve that will flatten the response and apply that to anything you cut. Harbal is a program you can purchase to aid in this analysis and curve generation.

You'll be able to use a Caruso pre-amp with my feedback cutterhead.

Good luck to you for Monday.

Cheers!

I thought the Caruso Inverse RIAA was one of the options, the BBC modified Presto 88A (uses 4 807 tubes puts out about 60 watts - you may need more than that for cutting microgroove or long playing discs - in old speak) so that the head was in the amplifier circuit and the feedback was added in one of the earlier stages which is another option - this is similar to the method that Fairchild used on their 641A (if I got the number right - their stereo cutter head). The feedback is applied as part of the feedback chain to an earlier stage - Inv RIAA would be applied in an earlier stage.

The Caruso board does this in the one board even though it is two separate processes? I need to refresh my memory on the block diagram for the Caruso.

Thanks for the good luck, but I do not do luck anymore than I suspect you do. Right now I need to dash as Friday afternoon has come around again and my scheduled coffee fix at a local coffee house is upon us once again.

Looking forward to any updates on the feedback angle of the stereo head. Oh yes and of course you can still cut mono with a stereo head. Two birds one stone and one basket.

[opcode66]

11 ohms dc resistance per coil is pretty high. Nemann was 4.7 ohms. Westrex 3d is 10. I've had a lot of luck with 8.

Please feel free to send me whatever you like. I'd appreciate it.

With respect to mono. I'm not ruling anything out. I just want to stay focused on the project at hand. Then, branch off.

Steve, if you don't use a moving coil, the alternative is to make a system where the cutting stylus is attached to a piece of iron. The iron is attached to a coil and in the presence of a horseshoe magnet. When audio is applied to the coil, the whole assembly moves (iron with cutting stylus as well as the coil). And, really it essentially teeters or rocks.

I can absolutely clone an RCA head. I already cloned the coils boards. Check out this thread.

http://lathetrolls.com/viewtopic.php?f=15&t=5205

[opcode66]

I thought the Caruso Inverse RIAA was one of the options, the BBC modified Presto 88A (uses 4 807 tubes puts out about 60 watts - you may need more than that for cutting microgroove or long playing discs - in old speak) so that the head was in the amplifier circuit and the feedback was added in one of the earlier stages which is another option - this is similar to the method that Fairchild used on their 641A (if I got the number right - their stereo cutter head). The feedback is applied as part of the feedback chain to an earlier stage - Inv RIAA would be applied in an earlier stage.

Yes, that is the typical scheme. So, what I'm saying is that you can use the Caruso pre-amp paired with a power amplifier. I am using a QSC GX3 300 W stereo amplifier. It has 70V rails. It is fantastic. Very low signal to noise ration.

The Caruso board does this in the one board even though it is two separate processes? I need to refresh my memory on the block diagram for the Caruso.

The Caruso provides negative feedback, IRIAA on the drive line, RIAA on the feedback monitor output, and the feedback monitor output itself. 3 trimmers: input gain, feedback gain, feedback monitor gain. There is a switch to turn off RIAA and IRIAA for calibration purposes. That is all.

Be well Steve. And, yes, I still have not taken a nap yet.

[studiorp]

When I had rewound my coil for 8 ohm, I haven't had success, so I have rebuilt with the original value divided for two. At the same time I had too built another coil mono, always with 23 ohm, for have a spare . All Pierre Clement has a coil among 22 and 24 ohm, it's a standard for this brand ( don't ask me why... ) .

[opcode66]

Ahhh. I see. Learn something new everyday!

[studiorp]

Yes, mine is an experiment. Consider that for me was the first time rebuild a coil from the original. After 3 or 4 attempts, finally I have obtained the right coil. I have used too the same thickness of orig. copper wire : 0,17mm, a medium misure.

But is possible calculate the freq. response knowing the dc resistance and the thickness of wire ( number of turns ) ?

[opcode66]

There are a lot of factors that affect the impedance. There are some ways to calculate it. But, always best to derive this value through testing.

Google coil impedance calculation. It makes a difference how many layers you have and the length of each layer. Number of turns and gauge are also factors.

[studiorp]

I have done a lot of researches and finally i have tried this software for calculate a multilayer inductor value : http://www.pronine.ca/multind.htm

These are the results for my mono coil ( not two in one, but only one ) rebuild :

https://www.dropbox.com/s/qt3315zvlvumzrx/Pronine%20Electronics%20Design%20-%20Multilayer%20Air%20Core%20Inductor%20Calculator.pdf?dl=0