Project Ryu - DIY Field Coil Loudspeaker - Page 16 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th February 2013, 03:41 PM   #151
diyAudio Member
 
Join Date: Dec 2008
From Ebay:spider speaker | eBay

Bernt
  Reply With Quote
Old 13th February 2013, 05:47 AM   #152
diyAudio Member
 
Join Date: Nov 2010
Default Voice coil clearance?

Question for Hentai and JMFahey, need data for another thread and you have experience!
A typically voice coil and former is about 1.2mm thick I think?
How much clearance do you allow to the pole piece?
Radial space of 1.5mm = 1.2 + .15 x 2 would be reasonable?

Best wishes
David

Last edited by Dave Zan; 13th February 2013 at 05:49 AM.
  Reply With Quote
Old 13th February 2013, 08:18 AM   #153
Hentai is offline Hentai  Romania
diyAudio Member
 
Join Date: Nov 2006
Quote:
Originally Posted by Frank40 View Post
Hi Hentai,

Sure I can make a pair of wizzers for you. But sense you have access to Machinery, the best way is if you make a former and send it to me. You can make it of any kind of hard plastic or even hard wood, and if you make it your self, you decide the dimensions. On the other hand... if you like I can show you in more details how I make them, the hard point is to make the formers when you don't have the prober machinery. Once you have the former, there is relay nothing to it.
Hi Frank, yes i will look into it, just thought you wanna develop your idea.

Quote:
Originally Posted by KaffiMann View Post
I apologize for intruding.

But where do you find a suitable selection of wire for VC?

Very nice thread btw! Best I've seen for ages!
Hello KaffiMann,

It really depends on what kind of wire you need. Copper wire is pretty easy to find, you should look at shops that wind transformers or do electrical motor repairs.

For aluminum or copper clad aluminum wire i only found in China and had to bring it in.

Quote:
Originally Posted by JMFahey View Post
For regular enamelled wire, check transformer winding supply houses.
Be CERTAIN to get "high temperature"wire, if possible "Class F/170 degrees Celsius" because nowadays thin wires often come in weak self fluxing enamel, which is designed to *evaporate* when hot.
VERY bad in a VC.
a good point

Quote:
Originally Posted by Frank40 View Post
I some one help me. I need a large spider for a 35.5mm voice coil but I can't find a dealer, I would like to finde one at around 120 to 150 mm.
Have you find the spider, i might be able to help in this regard.

Quote:
Originally Posted by Dave Zan View Post
Question for Hentai and JMFahey, need data for another thread and you have experience!
A typically voice coil and former is about 1.2mm thick I think?
How much clearance do you allow to the pole piece?
Radial space of 1.5mm = 1.2 + .15 x 2 would be reasonable?

Best wishes
David
Hi David,

It depends on many things and what you try to achieve. 1.2mm VC thickness is pretty thick for a fullranger but ok for a woofer and could be thin compared to some subwoofers.
a space of .15 between VC and polepiece can be pretty tricky and will give you lots of pain to avoid rubbing. Again considering the thickness of VC i imagine it can eat up some power and you need to consider the increase in thickness once it starts to heat up.
  Reply With Quote
Old 13th February 2013, 11:25 AM   #154
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Question for Hentai and JMFahey, need data for another thread and you have experience!
A typically voice coil and former is about 1.2mm thick I think?
How much clearance do you allow to the pole piece?
Radial space of 1.5mm = 1.2 + .15 x 2 would be reasonable?
Can't give a "generic" answer, it depends a lot , as noted above, on what kind of speaker we are talking about.
Split your problem:
1) typical former material is around 0.1mm (forget Inches here, not precise enough)
A tweeter might use 0.08mm and a ridiculous "1000W" car woofer might use ,say, 0.15mm
2) For initial calculation: wire is wire, whatever you actually measure is true.
Add 0.1 to 0.2 mm total (not per layer) to account for adhesive and/or some small winding imperfection.
Anyway: as soon as you have your sample VC, measure it.
Still add 0.1 to 0.15 mm to account for imperfections, tiny bubbles in epoxy, etc.
3) minimum "inside" clearance is 0.125 mm , that's what I use for my guitar speakers .
In a midrange or tweeter you *might* use 0.1mm .
3) On the "outside" you will need minimum same as inside, but in production stuff it's common to raise it to 0.2mm and even 0.25mm.
Why?.
Because on the inside you have the centering shim which "sweeps clean" that space so any dust spot will be pushed or cleared away; any "invisible" dust or whatever particle in the outside space will not, and give you headaches.
Unless you work in a guaranteed dust free room.
It also accounts for the VC expanding under heat (something many ignore)

These measurements are a reasonable compromise between efficiency and real World production.
JBL and others work with tighter tolerances because they can; typical cheap Chinese speakers (or Car speakers) show impressive frames and magnets, but use huge gaps (invisible to the customer) which waste most of the magnet energy.
Even JBL had to "open up" the gaps in speakers made for Fender, go figure.

NOTE: also consider the metal parts paint thickness.
Typical oven cured Epoxy or powder coat is *very* thick, I hate it.
I zinc plate all magnetic structure parts because it's thin and strong.

Last edited by JMFahey; 13th February 2013 at 11:28 AM.
  Reply With Quote
Old 13th February 2013, 12:59 PM   #155
Hentai is offline Hentai  Romania
diyAudio Member
 
Join Date: Nov 2006
As a practice i tend to center the voicecoil in the gap as in the same distance for inner and outer clearings. I also go with inside outside winding to keep it as symmetrical as possible and a smooth BL curve altho you might get a slight increase in B value close to the pole piece. Also no problems when dealing with T shaped polepieces.

Also one needs to consider if copper rings are added in the gap.
  Reply With Quote
Old 13th February 2013, 05:44 PM   #156
Frank40 is offline Frank40  Denmark
diyAudio Member
 
Frank40's Avatar
 
Join Date: May 2004
Location: My workshop :-)
Hi there

Dave Zan, I measured the air gap on the two different I took apart they were 1.5mm. Since I am using ties magnet for starters , that is what I will be using.

Hentai, Thanks.... But I did placed an order now, and they had a min. purchase of 25$ so I got a variety of sizes.

I did make a new former for a 6,5” without wizzer, I want to se if it will work whiteout the wizzer. If it doesn’t I have the former to make a wizzer. Also I am trying to copy the former using liquid latex, but it is to early to say if it will work.

Just a note: I did get a normal voice coil and the weight of it is 6.5g.

Here is some pic's of the new former. The former is slightly modified now.

Take care
Attached Images
File Type: jpg Capture_371.jpg (463.6 KB, 640 views)
File Type: jpg Capture_372.jpg (402.2 KB, 617 views)

Last edited by Frank40; 13th February 2013 at 05:46 PM.
  Reply With Quote
Old 14th February 2013, 10:30 AM   #157
Hentai is offline Hentai  Romania
diyAudio Member
 
Join Date: Nov 2006
Very nice pics.

A bit heavy the voicecoil.
  Reply With Quote
Old 18th February 2013, 08:09 AM   #158
Frank40 is offline Frank40  Denmark
diyAudio Member
 
Frank40's Avatar
 
Join Date: May 2004
Location: My workshop :-)
Hi there

I was thinking about the spider suspension and it seems to me, that the spider it a place where we can do some improvement. My thought is- in order to move the spider, it require energy this comes from the voice coil. So it should be consider as a loss.

My idea is to use a soft (slow) glue between the spider and to voice coil, this way the spider dose not move at high frequency because energy is not transferred from the voice coil. It seems to me that this will give a smaller loss at high frequency.

Please coment.
  Reply With Quote
Old 18th February 2013, 10:25 AM   #159
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
In theory it's something, but compare the weights, you have, say, a 20 gram cone and 1 gram of suspension.
Even if you fully decoupled the suspension it's not that much saving.
The big deadweight at high frequencies is the VC itself.
That's why they make speakers with aluminum wire (totally out of the question for home builders )
Also why "paper former sounds best", it's the lightest one.
In order of quality they are:
Paper > Nomex > Kapton > Fiberglass+Epoxy > Aluminum
  Reply With Quote
Old 18th February 2013, 03:15 PM   #160
Frank40 is offline Frank40  Denmark
diyAudio Member
 
Frank40's Avatar
 
Join Date: May 2004
Location: My workshop :-)
Hi JMFahey,

Thanks for your answer....If there is any chance for improvement I will use it, no need to not to try to make it better. I can se you like paper cones, I my self do not have a preferences.... what ever sounds best.

A cone that weighs 20g is heavy.... The new light weight cone I made is only 2.6 g. I have added some Thixotropiennittel, this allow the epoxy not to harden fully this will increase the damping of the cone.

This is how it will look when done.

Take care
Attached Images
File Type: jpg Capture_371.jpg (591.9 KB, 523 views)
File Type: jpg Capture_372.jpg (661.7 KB, 507 views)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
First DIY loudspeaker project for LM3886 kiske1 Full Range 68 26th April 2012 03:27 PM
Open baffle field coil project jonjin Multi-Way 1 6th December 2010 11:19 AM
Has anyone DIY a Field coil? OzMikeH Full Range 18 16th November 2010 01:56 PM
field coil? otto88 Markaudio 0 2nd October 2010 03:33 AM
What's a Field Coil Amplifier? krzanik Tubes / Valves 9 14th May 2005 03:22 PM


New To Site? Need Help?

All times are GMT. The time now is 08:51 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2