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

[juba bc]

very good, thanks for sharing ... I'm learning a lot from his construction

[flozki]

nice one! congratulation!
if you want to stay comatatible for the LED:
use Pin 12 for Anode
and Pin 10 for cathode of LED.

i never documented the LED. and so far not assembled in the first 20 heads. .
but LED was designed in already in th beginnig of caruso.
there is a 5mm hole in the head body for that LED. all prepared.
only mounted in first few prototypes.

new official setup manual is shortly to be released as well as new preamp board generation.
as we run off the preamp boards. should be here in 2 weeks.
additional features:input mute circuit & extra RIAA encoder out for easy non feedback operation.
also more space and universal footprints for the important caps.

[Snug Music]

new official setup manual is shortly to be released as well as new preamp board generation.
as we run off the preamp boards. should be here in 2 weeks.
additional features:input mute circuit & extra RIAA encoder out for easy non feedback operation.
also more space and universal footprints for the important caps.

hey flo,.
remains the price as the old board or change this upward? I would be interested!
regards Scotty

[EpicenterBryan]

nice one! congratulation! if you want to stay comatatible for the LED:
use Pin 12 for Anode
and Pin 10 for cathode of LED.

Hi Flo!
I'm using some segments of LED strips that have built in resistors, so they require 12vdc. I'm going that way since I'm using similar light strips on the lathe for general lighting. But that's cool to know. I assume an external resistor was your intention for the LED connection?

I'm wiring things, and trying to be compatible with Caruso and the pinout you published below...


Drive Left + Pin 3
Drive Left – Pin 11
Drive Right + Pin 6
Drive Right – Pin 13
Feedback Left + Pin 1
Feedback Left – Pin 9
Feedback Left Shield Pin 2
Feedback Right + Pin 8
Feedback Right – Pin 15
Feedback Right Shield Pin 7
Heater + Pin 4
Heater – Pin 5

I talked with Mark today and he pointed me to an interesting thread for others to read here, and I am not clear:
http://lathetrolls.com/viewtopic.php?f=1&t=5526&hilit=absolute+phase+polarity

Can you define which driver you call right on Caruso? Is that the one that cuts the groove wall that is furthest on the outside of the disc? And which driver and FB has the polarity reversed?

Below is a photo showing my nomenclature and I want to make sure this agrees. The driver physically on the left of the head I call right, since it cuts the outer groove on the disc. The driver physically on the right of the head, I call left since it cuts the inner side of the groove.

Notice in the photo I have a note on what I call the left driver that the polarity is reversed for Drive and FB.

Does this agree with your definitions?

Bryan

IMG_4475.JPG

[EpicenterBryan]

The guts are wired!

Those feedback wires kicked my butt today. Ultimately I abandoned the the circuit board idea and terminated the wires to header connectors. Then mating connectors hot glued to the inner head body. There are short segments of kapton tape as an insulator under the FB wires, and more kapton tape to hold down the fragile wire. This leaves me a slight possibility to fix something in the future by leaving the wires as long as possible (but still twisted).

IMG_4477.JPG

The next step is to install the push rod extensions, torque tube and all that... The alignment tool is being printed tonight. But let me show you how I'll hook those 3mm OD, 2mm ID feedback tubes to the final segments of the push rods.

pushrods in and out.jpg

The final segments consist of a piece of 2mm OD, 1mm ID aluminum tubing, and a piece of 1mm phosphor bronze glued inside the aluminum. This photo shows that the rod can be adjusted in our out of the tube that has the feedback coil.

In reality, the actual rod segments are more like these shown below. Total length is about 10mm, but will likely be trimmed shorter as everything gets aligned...

IMG_4474.JPG

That's it for tonight.

Bryan

[Sillitoe]

Caruso Coils LEFT AND RIGHT.jpg

3.png

Nice one Bryan, looking good!
You have the drivers labelled correctly.

Can't wait to hear it!

Cheers
James

[sakuszi]

well, instead of use apply an LED light , use halogen bulb 100W 12V car, to heating plate cutting, you thought about this?

[EpicenterBryan]

You have the drivers labelled correctly.

Thanks James! Just what I needed.
Should have some results in a few days. Got a ton of stuff done last weekend.

well, instead of use apply an LED light , use halogen bulb 100W 12V car, to heating plate cutting, you thought about this?

I don't really have room in the head for that. But I will be adding heated stylus at some point.

Bryan

[Snug Music]

Hi Bryan, ..
've just seen what you've done.
PERFECT!!!
That looks really good, look forward to the first cuts!
If this works, I modify my driver just like yours!
That's Great Bryan ... you are really a champion!

best regards Scotty

[Snug Music]

Caruso Coils LEFT AND RIGHT.jpg

3.png

Nice one Bryan, looking good!
You have the drivers labelled correctly.

Can't wait to hear it!

Cheers
James

hey Sillitoe,.
that is, the rights canal would make a downward motion with a signal and the left channel upward movement. or I understand that wrong now?
'm just confused!
So the left channel plus to minus and minus to plus is that correct ??

regards Scotty

[EpicenterBryan]

hey Sillitoe,. that is, the rights canal would make a downward motion with a signal and the left channel upward movement. or I understand that wrong now? 'm just confused! So the left channel plus to minus and minus to plus is that correct ??

For mono (lateral), the same signal is fed to both channels of the amplifier. The output of both channels from the amplifier are in phase with each other. But one channel inside the head has to have the polarity of a driver reversed. From what I understand the Left one gets reversed. Then when the right channel sees a positive going voltage it pushes, and the left channel does the opposite - it pulls. That causes the push / pull lateral motion.

The polarity swap on one channel could either be done at the amplifier or at the driver in the dead. It is customary to do the polarity reversal in the head. But you still call the signals + and - at the head interface so it's easy to hook the amplifier up and maintain the correct polarity.

Bryan

[Snug Music]

aha ... Thanks Bryan!
I had the driver in the reverse direction!
yes, .. from the interface!
ok, .. then I want the times change quickly!

Thanks for the quick response form, you're really the best!

best regards Scotty

[Sillitoe]

That image is from Flo.
It is consistent with what dubcutter89 posted as being the defacto standard for Neumann and Ortofon heads.

Much respect to those guys!

Cheers
James

[sakuszi]

not enough to get the stereo effect

[EpicenterBryan]

Progress has been made!

Here are some shots of the install of the push rods. I made an alignment tool to keep the stylus holder perpendicular and centered in the head. I used a drill bit in place of the stylus. I first inserted short segments of the 2mm to 1mm aluminum adapters and 1mm Phosphorus Copper rods into the 2mm ID driver tubes. I held them in place with mini alligator clips. Then raised them up and glued into place. There was a mess up - I'll go into it later if it's an issue.

rod install.jpg

While adjusting things, a wrench was sucked out of my hand and went straight to the Left channel feedback magnet which cut one of the Left FB coil wires. CA was already applied to all the connections so it was a race to correct things. I was pissed off!

Ultimately, I was able to get in there and solder the severed wire. This is a task better suited for a younger man with better eyesight for sure. The little "J" looking thing on the wire is where I was able to connect the wires.

cut FB wire.jpg

Here is a shot that shows a push rod (2mm OD/ 1mm ID aluminum tube) and 1mm Phosphorus Copper rod installed between the driver and stylus holder.

Rod closeup.jpg

And here is the frequency response of the head on the bench now that everything is connected. Everything on the left is for the left driver. Everything on the right is for the right driver. I also tried to simulate a cutting load while these measurements were made to get a sense of the stability. It looks great.

But now that mass has been added, the HF has dropped as Markrob has noted before. It can be addressed externally, or if I make changes to the Behringer parametric EQ's I've noted before...

GS response Left - Right.jpg

Two measurement iPads were used at the same time. And each was driving the respective channel with it's own noise source and measuring it's own response. I also did a quick visual on channel separation by driving only one channel and looking at the feedback signal from both channels. I'll need to do it in a more scientific way, but it looked to be in the 20db range which is nearly as good as most of my phono cartridges. We will see how the numbers go on an actual left / right only cut.

That's the update for tonight.

Bryan

[EpicenterBryan]

Just to make it clear.
The top plots are the frequency responses with no feedback or EQ. The bottom plots are with feedback and with EQ in the FB path prior to the power amp.

[sakuszi]

Just to make it clear.
The top plots are the frequency responses with no feedback or EQ. The bottom plots are with feedback and with EQ in the FB path prior to the power amp.

a lot of work, but heard nothing

[EpicenterBryan]

a lot of work, but heard nothing

Yes, I know.
I am a methodical kind of guy. I'm a former engineer. Before I post a new "epic test cut video / audio cut" I want to make sure I have double checked everything. After all, I have spent over a year messing with these drivers. I am not saying these drivers are the way to go at all! I am only trying to finish work that may make them usable. I would not recommend them for a new build, but I feel I should rap up the build and see / hear if it works.

What I liked in the beginning about these drivers was that they could be "hacked / modified "... but I don't think they are as well suited for this application as I originally thought. Especially when you see in this thread the magnitude of modifications needed to get the drivers to respond better than the stock drivers.

So be patient my friend. I'll post audio cuts only after I have learned as much as I can making this head and these drivers as good as I can. I am near the end messing with this. Near the end of what I can do. Near the end of what I can learn messing with what may be totally flawed.

And for people just now jumping into this thread, let me say that I have no interest in selling you a head in any form. I have no interest in selling you parts. I have no interest in making any money in anything related to this thread. This thread belongs to everyone who has contributed to it.

Bryan

[Snug Music]

Just to make it clear.
The top plots are the frequency responses with no feedback or EQ. The bottom plots are with feedback and with EQ in the FB path prior to the power amp.

a lot of work, but heard nothing

Hey

I can very well understand Bryan! in fact, we have been more than a year here, this driver to hack / modify and I can understand Bryan when he (I'm doing it exactly!) all double-checked in order to avoid errors. because you have to just understand us, it is our free time we devote here to build this driver finished him /. I myself am not an engineer, but I have learned in a very short time of Bryan and other people in this forum very much. I have a very great respect for what Bryan does here. and am very grateful to him. as Bryan mentioned earlier, this contribution in this forum, is for all who deal with this driver. without financial interests! thank Bryan !!!

regards Scotty

[sakuszi]

I say this without sarcasm. I want to hear 10 seconds recording your head. A lot of work . What is the minimum effect. Without recording, cutting or stamping ,press nothing at all I can say. also do not use a microscope, it is unnecessary. Time and recording level comparing with professional recordings, gramophone plate test. I did some serious recording very primitive wooden machine diy, real, I'm not doing the base of MP3, etc., it would be nonsense, and immediately heard a digital recording, do not even need analyzer pc ...