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

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

Post: # 45174Unread post EpicenterBryan
Tue Dec 13, 2016 12:02 am

Thelurker wrote:Can I ask, why you used white noise instead o pink noise for the measurements?
Depends on what measurement software you plan to use. RTA usually uses Pink Noise. FFT applications usually uses White noise.

Pink noise info:
https://en.wikipedia.org/wiki/Pink_noise
White Noise info:
https://en.wikipedia.org/wiki/White_noise

Check the software you plan to use and supply the noise source recommend for the measurement algorithm the software expects...

Did that help?

Bryan

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

Post: # 45206Unread post EpicenterBryan
Thu Dec 15, 2016 7:17 pm

Here is the first look at some feedback testing I've been playing with for the PICANTE head:

Here is the test fixture and a split bobbin for the feedback coil. Initial testing was with a rather large ID size magnet (smaller ones have since arrived), so I needed to space the wires closer to the magnet. But the end of the funnel is tapered, so I opted to make the bobbin in 2 parts and hand ream each so they fit exactly where I wanted them. Then I glued them together and glued them to the funnel.

On this version you see an attempt at some copper shielding and also a steel washer in there. Not much room for anything else. But I just ran across a magnetic iron 3D printing material and I'm going to give that a try. It's called "Proto Pasta". Not only is it magnetic, it also weighs about 1.5 times what a plastic part would weigh.
FB test parts.jpg
FB test jig.jpg
Since I had already glued the funnel to the driver, I made an adapter to spin the entire driver on the coil winder. On this driver I got the commands backwards and ran the surround into the wire block and chewed it up a bit. That's why the surround has been patched with black speaker glue.
IMG_5351.JPG
The first round of testing worked to an extent. When I saw so much high frequency in the feedback I didn't really trust what I was seeing and figured I would try to do more shielding (and try the Proto Pasta) before spending too much more time on it. We know how much of a time sink hole feedback can be...

Anyway, I'm about ready to give it another shot.

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

Post: # 45207Unread post grooveguy
Thu Dec 15, 2016 8:21 pm

Looks like you're on a mission, Bryan, and making good progress. Our best wishes are with you.

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

Post: # 45224Unread post Snug Music
Sat Dec 17, 2016 2:35 pm

So,..now i´m back again...

hey Brian,..
i see whats goin on here..
hey,..thats great man...wow :shock: :shock: :shock: :mrgreen: :mrgreen:

next time i will make pictures from my head and machine what i have made.
stay tuned..
best regards
Scotty ( i will be back...) :lol: 8) :mrgreen: :mrgreen:

BTW: Good Luk :wink:
I'm still not a professional, but I learn pretty fast. especially with my eyes and ears!

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

Post: # 46299Unread post crowesBR
Sat Mar 04, 2017 12:50 am

How this drivers sound?
Planning to get some instead of the phonocar 2/419.

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xave2000
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Re: Project: OsoMiso - PICANTE - a 45/45 stereo head

Post: # 52266Unread post xave2000
Thu Jan 31, 2019 8:28 am

Hello very nice work! I wanted to know what was the principle of the coil on the funnel and also what is the principle of the big iron square? thanks for your help

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

Post: # 52275Unread post EpicenterBryan
Thu Jan 31, 2019 9:24 pm

xave2000 wrote:what was the principle of the coil on the funnel and also what is the principle of the big iron square?
The coil was for generating a feedback (error) signal to be subtracted from the source to compensate for incorrect frequency response. The block was for testing the magnet structure for the feedback coil, and to verify isolation from the fields generated from the driver getting into the feedback signal.

Implementing feedback is tricky. There is lots of discussion about it in my thread on the project called "Groove Scribe".

I did not finish playing with feedback on this head but may come back to it in the future. So many projects, so little time.

Bryan

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

Post: # 52276Unread post grooveguy
Thu Jan 31, 2019 11:37 pm

Hey, Bryan, what sort of magnet structure will be used with that feedback coil? Has anyone tried a capacitance feedback pickup? Seems it would be pretty simple, low-mass, frequency-flat and immune from magnetic coupling with the drive coils. Just a thought.

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