Project: OsoMiso - PICANTE - a 45/45 stereo head

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EpicenterBryan
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Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44931Unread post EpicenterBryan
Fri Nov 25, 2016 5:53 pm

Hey guys,
Lots of progress to report on all the various projects. I'll start updating the posts starting shortly.

In this one... It's the first look at what I call OsoMiso - Picante.

This version is non-feedback but I have also been playing with a feedback version and will share some info as I make more progress.
The original plan was to use tweeters. For various reasons I'll discuss in additional posts, I have decided to use full range drivers.

Here are some drawings that will quickly show how the head is laid out. The body on this version is 3D printed. It was designed such that it could be printed with no support material with it's back mount facing down. It has a separate front part in front that screws in and can be changed as needed. Right now I have LED's mounted on the inside of the front part. When the time comes I'll add spring clips for heater wires and swap out the front part.
Picantex4.jpg
Hot off the printer...
IMG_4929.JPG
The head has already been tested, EQd with 20 bands of parametric per channel, and a test song has been cut. I let Mark and John hear the first test cut and we are all quite impressed. Since then I've made a few changes to the calibration chain and a few little changes to the head, so I'll be doing a new calibration this weekend and will post response curves and a new test cut, so stay tuned.

The head was designed to incorporate a Neumann style torque tube and V spring (made by ROLANDJAYS), and a Neumann 320 stylus. The body incorporates a Presto mounting pattern on the back and also has a built in 8 degree back angle mounting slope. The overall size is smaller than Groove Scribe!

I'll be doing one more body design that will make it a little smaller, and it will be simplified so the body can be machined out of aluminum with fewer milling operations.

As you see from the underside, it uses diaphragms which serve the same purpose as X springs to keep the drivers centered as they move in and out.
IMG_5321.JPG
IMG_5322.JPG
I also added a swarf tube. So hopefully that will be working this weekend.
Recently I've been cutting inside - out and playing the cut groove at the same time as cutting which has made adjustments faster. More on that later.

Bryan
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ROLANDJAYS
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44933Unread post ROLANDJAYS
Fri Nov 25, 2016 9:47 pm

oh yea look at that :shock: :shock: :shock:

:mrgreen: :mrgreen: :mrgreen:

8) 8) 8)

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44935Unread post EpicenterBryan
Fri Nov 25, 2016 10:26 pm

ROLANDJAYS wrote:oh yea look at that :shock: :shock: :shock:
That's your handy work in there John... The core of what you heard a few days ago plus my secret sauce... (for tonight).

Your Salsa head will sound as good or better with the tweaks we discussed. I'll start a thread this weekend on the first version of "Salsa" if you are ready to start the mods for V2.
Are you ready?

Bryan

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Soulbear
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44940Unread post Soulbear
Sat Nov 26, 2016 6:54 am

Hi Bryan,
I'm loving this design and looking forward to your updates. To sum up your achievments here in one word, "WOW!!"
Regards :wink: :P :D Soulbear

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grooveguy
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44974Unread post grooveguy
Mon Nov 28, 2016 9:51 pm

Nice looking head, Bryan, we want to hear it! What are those drivers? And is the clamped end of your 'torque tube' (that carries the stylus) mounted rigidly to the housing, or does it have a rubber gasket or whatever?

Hey, I was wondering... The right way to do any of this is to make a feedback cutter, of course, but that does complicate the mechanical design, and introduces unknowns in the electronics, in terms of phase shift, transformer coupling, etc. Most all feedback systems thus far use a second electromagnetic transducer of some sort, but I wonder if anyone has used a capacitance pickup of any kind. The old Weathers phono pickup was a a very simple capacitance design, and I have some articles on how homebrew condenser mics can make use of RF modulation techniques to avoid high polarizing voltages, leakage paths and other hassles associated with the traditional condenser mic circuitry. There must be a number of ways to 'close the loop,' so to speak.

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44984Unread post EpicenterBryan
Tue Nov 29, 2016 7:10 pm

Hi guys,
Didn't get everything done that I wanted to this weekend. It ended up taking more time than planned to get swarf removal working well enough among other things.

I hope to do a new music test cut tonight with the updated EQ curves below and get that posted.
For now, here are some important things... First the left and right frequency response.
Details: Response curves obtained with white noise, no riaa or Iriaa using Wayne's flat preamp and Shure M97xe phono cart. Source: Protools TDM mix system, 48khz sample rate, phase linear 400 power amp. No heat lamp, no heated stylus, 45rpm, 16" disc about mid way.

Note that the software scaled the two channels differently, so you have to spend a bit of time looking at the scale on the left to really compare the two channels. I had no control over that.
Picante Response 11-27-16.JPG
One obvious thing about the response curves... yes, all that HF response is real and not errors in measurement.

With 20 bands of parametric EQ per channel the actual and predicted response is as shown below.
First the LEFT channel. Dark Red is actual response. Lighter curve is the predicted response after EQ.
Picante LEFT EQ 11-27-16.JPG
Below is the RIGHT channel. Dark Green is actual response, lighter green is the predicted response after EQ.
Picante RIGHT EQ 11-27-16.JPG
The channel separation @1khz on the last test came out to 14.4db when only driving the LEFT channel, and 17.7db when only driving the RIGHT channel. So there is more work to be done to make sure the channel drive is better balanced on the next test.
grooveguy wrote:What are those drivers? And is the clamped end of your 'torque tube' (that carries the stylus) mounted rigidly to the housing, or does it have a rubber gasket or whatever?
Hi Jim,
I'll go over drivers in another post. As far as the Torque tube goes, it's set up like I did it on Groove Scribe. The tube goes slightly through the V spring and is glued to the spring. The body has 2 mounting points for the spring, and a cavity so the spring can flex and only touch the body where the screws are. Then the drag ling is glued to the tube and is clamped to the body from underneath.

On the last round of testing I filled the cavity between the body and V spring with RTV as a dampener. There was little if any affect in response.
grooveguy wrote:...but I wonder if anyone has used a capacitance pickup of any kind.
I'm not sure if anyone has tried that kind of pickup. I'm pretty sure Flo experimented with Hall-Effect sensors at some point. I tried using a phono cartridge on one of my heads. MarkRob has been playing with eddy current sensors. I've also been playing with coils for this head. More on that at a later date.

Bryan
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grooveguy
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44985Unread post grooveguy
Tue Nov 29, 2016 8:28 pm

Looks like good progress, Bryan, and thanks for the answers to the questions. With respect to separation, I'm still in favor of matrixing L and R for sum and difference, and then playing with the gain in the difference channel before de-matrixing back into L and R. Might gain some dBs there, dunno. Keep us updated, please.

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44988Unread post EpicenterBryan
Wed Nov 30, 2016 12:52 am

grooveguy wrote: With respect to separation, I'm still in favor of matrixing L and R for sum and difference, and then playing with the gain in the difference channel before de-matrixing back into L and R.
I'm with you on that one. It's easy to play with the concept in Audacity for free for people who would like to experiment and gain knowledge. I'll work up a procedure that people can use to experiment with it. And Wayne makes MS encode / decode boards available as well. I plan to pick them up as well. Not enough time tonight to go into it...

Bryan

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44989Unread post EpicenterBryan
Wed Nov 30, 2016 12:57 am

Here is a quick bounce for tonight...
https://soundcloud.com/epicenterbryan/picante-test-bounce-11-29-16/s-MLFrw


Sad to say that what SoundCloud posted sucked. The source was 24 bit, 48khz. I'll try to find a better solution for people to hear these cuts...

Bryan

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grooveguy
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44990Unread post grooveguy
Wed Nov 30, 2016 1:19 am

Boy,

I dunno. What I heard sounds pretty darned good!

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Sillitoe
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44991Unread post Sillitoe
Wed Nov 30, 2016 1:33 am

Nice Bryan! :wink:

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44992Unread post EpicenterBryan
Wed Nov 30, 2016 1:38 am

grooveguy wrote:Boy, I dunno. What I heard sounds pretty darned good!
Thanks for the note Jim. In my office it sounded pretty crappy. Time to upgrade these PC speakers to the real deal. Sounded much better before posting from back in the man cave...

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Ciuens
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44994Unread post Ciuens
Wed Nov 30, 2016 6:17 am

Hey Bryan, amazing sound quality.
you are the man, haha. :wink:


Ciuens - ZEZ Cutter One

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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 44997Unread post inspector77
Wed Nov 30, 2016 7:26 am

:shock: Congratulations! great quality!!!!

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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 45002Unread post socialroots
Wed Nov 30, 2016 8:47 pm

Boom! Big up on the results thus far, like grooveguy already said sounds really good already and Im listening thru my smartlphone speakers! I think your over critical cuz your the builder. Great development team you got as well, maximum respect to the knowledge and expertise of Mark Robinson and John Batchelder . Right now you guys got me hoping and dreaming that the final specs will be mountable on my Rek O Kut M 12! You never seize tho amaze Bryan, I for one am thankful that your applying all your yrs of know how into the cutting game.
Bless,
Patrick

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 45035Unread post EpicenterBryan
Fri Dec 02, 2016 11:04 pm

Thanks everyone for their inputs on what this thing sounds like. Much appreciated.

Here is a quick update for tonight. I should have time to post more this weekend.
One thing I liked about this design was the ability to swap out the front plate when the need arose.
I got my hands on 10 of those "diode clips" as Jim called them. These were a little longer that I would have liked but they are so damn hard to find I made due...
diode clips.jpg
It took a few trial and error prints to get them positioned so they cleared everything inside the head and didn't add too much height in the front so everything cleared when cutting. At first I lost the space for the 3 LED panel so I went with a single LED and it worked out OK. As I had to move them down more and more, now it looks like I have room again to make the LED panel fit so I will probably do that this weekend. I like the warm white better than the cool white anyway.
IMG_5332.JPG
I also got the swarf tube installed and it works well on it's own. But I'm having issues with clogging down stream so I'll be messing with that and have new latex tubing on the way to replace sections that are not latex. The actual tube in the head does not clog - it's a down stream issue but I still get 5 minutes of cutting or so before it's an issue.

In this shot you see some "goop" I put on the push rods and behind the V spring to see if I could dampen any of that HF. It had zero effect. The root cause is not accessible now that everything is glued so I'll look at that on the next version before I assemble.
IMG_5334.JPG
That's about all the time I have for tonight. Stay tuned.

Bryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 45036Unread post grooveguy
Fri Dec 02, 2016 11:07 pm

Bryan,

You are doing some groundbreaking work here. Keep it up!

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 45037Unread post EpicenterBryan
Sat Dec 03, 2016 12:02 am

socialroots wrote:Boom! Big up on the results thus far, like grooveguy already said sounds really good already and Im listening thru my smartlphone speakers! I think your over critical cuz your the builder. Great development team you got as well, maximum respect to the knowledge and expertise of Mark Robinson and John Batchelder . Right now you guys got me hoping and dreaming that the final specs will be mountable on my Rek O Kut M 12! You never seize tho amaze Bryan, I for one am thankful that your applying all your yrs of know how into the cutting game.
Bless,
Patrick
Hey Patrick,
I wanted to comment on your post for several reasons. First, I appreciate what you said about how Picante sounds!
But I also wanted to second your thoughts about Mark and John's participation. These guys are two of my favorite people. I only wish they lived closer and we could all hang out and build things!

As far as your M12 goes, any info you have and can send on the over head would be useful. Especially anything that relates to head mounting or what the optional heads were.

Bryan

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EpicenterBryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 45157Unread post EpicenterBryan
Sat Dec 10, 2016 4:59 pm

A quick update and back fill on this project:

The first driver I was going to use on this head was a Dayton Audio ND20FB-4 Rear-Mount 3/4" Soft Dome Neodymium Tweeter. The outer plastic had to be ground off to have full access to the dome.

The original plan included coating the silk dome with several coats of super glue. Then I made a jig to hold an aluminum ferrel that came from a rivet. The rivet was glued to the top of the dome and baking soda with super glue was used to fill the gap.
Tweeter version.jpg
Remember that I was working on the ONO head at the same time, and used a similar scheme to coat the dome and install a push rod of sorts.

Testing of the ONO head by cutting a record found a large roll off at high frequency. MarkRob also verified the same roll off when using his eddy current sensors to measure displacement on the head. So we determined that the dome coating idea was not the way to go. Either it didn't have enough stiffness to allow the mass to move at high acceleration, or perhaps it wasn't coated all the way to the voice coil under the dome.

Either way, I decided not to use the tweeters and I went back to a driver I have used before - but with extra sauce this time... Here is the Aurasound NSW1-205-8A 1" Extended Range driver I used:
nsw1-205-8a.jpg
This one has an inverted titanium dome. The surround extends and is glued over the ideal gluing location where the voice coil is but attachment could be made very close. So the next thing to do was come up with a cone / push rod.

What I ended up finding were little aluminum funnels for perfume bottles. Yes, you heard that right.
It turns out Soulbear actually discovered these on his Soul Sculptor post:
http://lathetrolls.com/viewtopic.php?f=15&t=6556&p=42324&hilit=perfume#p42324

The ones I found came it at 1gram when full length, but when the excess was trimmed off like shown below the weight came down to 0.6 gram. Here you see a full length one, and one that was cut down.
Driver with cone.jpg
I tried several ways to cut them down with tools I have, and what I ended up doing was put a screw and nut through the funnel and spun it with a hand drill while using a grinder. Then sanded the end as shown below:
Cone trimming.jpg
Mark has been playing with a similar idea for the ONO drivers. Perhaps we will have an update on that project as well...

I have also been playing with feedback for this head, and just received something that might help shield things so I can get more useful range. I'll post about that shortly...

Bryan
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 45172Unread post Thelurker
Mon Dec 12, 2016 6:49 pm

Great stuff Bryan

Can I ask, why you used white noise instead o pink noise for the measurememts?

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