Impedance technical questions - Car Audio Classifieds!
Car Audio Classifieds!  

Go Back   Car Audio Classifieds! > Car Audio Help & Discussion > Testing & Scientific Data Discussion

Testing & Scientific Data Discussion Results from Speaker and amplifier Testing


Notices

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-16-2015, 11:22 PM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default Impedance technical questions

I understand that impedance rise isn't always a bad thing. Enclosures are often very efficient when impedance is the highest. The two may or may not be related depending on the install.

Will infinite baffle have more or less rise than a ported enclosure? I have gotten different answers from different experts.

So, what is the best way to fight impedance rise? Some full bridge Brazilian amps have special circuitry to help compensate for rise, but they do not completely eliminate it. I am going to run a Taramps 30k, and don't want to wire it low in order to get the full power out of it.

I know that the stronger a motor is, the more drastic impedance rise will be. That is one of the reasons that neo motors have higher rise.

It was brought to my attention that adding a pole sleeve can reduce impedance rise. I had previously thought that pole sleeves were only used in Sundown Nightshades as shims, because there were many different coil options. What material are pole sleeves like this made out of? Aluminum, copper, steel, or something else? I'm guessing most are aluminum and some are copper. Apparently, pole sleeves reduce rise, but also reduce motor force.

What affect does "supercharging" with neo magnets on the pole piece have on rise? The primary purpose of the magnets is to direct more flux back into the gap, according to DD.

Will a copper shorting ring on the tip of the pole piece affect rise? I have heard that it reduces back-EMF, but am not sure.

A far as damping, I have also heard that the amplifier used affects rise. Is there any more public information about amplifier damping factor?

I'm interested in designing and building a neo motor for a 5" b2 coil, and want to get the maximum I can out of my amp.

Does anyone have interesting information about coils?

Copper is more efficient, but it is heavier than Aluminum. Aluminum can handle more power because it dissipates heat faster, and is lighter by volume. Which would yield higher rise. If I had to guess, I'd say aluminum.

Please share any other information you have about the technicalities of subwoofer motors, rise, and/or amplifiers.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 05-16-2015, 11:50 PM
Jeffhulbert50's Avatar
Authorized Vendor
 
Activity Longevity
0/20 14/20
Today Posts
0/11 ssss14115
Location: middle of east
Thanks: 65
Thanked 1,756 Times in 1,344 Posts
iTrader: (83)
Feedback Score: 83 reviews
Default

pole sleeves are exactly as they sound. a sleeve (tube) of material. sleeve helps visualize that its a solid piece. look at a coil former, notice it has a slit/separation. that's to prevent shorting. the pole sleeve AKA shorting ring/sleeve creates a closed circuit to absorb eddy currents.

using a sleeve makes a motor weaker because it makes the gap larger (requires a smaller pole to make room for the sleeve) if the pole needs to be 3.00 OD and the sleeve is .10" thick, you need to shave the pole down to 2.9 thus the gap is "wider"

some are aluminum, some are brass, others are copper. each material has its thermal/shorting/cost advantage/disadvantage

the supercharge option is almost a one sided bucking magnet. the pole is often the weakest link in magnetic loop. placing a magnet in top of the pole (with matching magnetic poles touching) works to increase the strength by making a secondary loop between the top of the top plate and the pole. the bad portion is increased stray flux since the open pole is rather generous in its flux spread

copper on the pole will help in a similar manner that a pole sleeve has. its a shorted material that has the property of magnetic interference/manipulation.

as far as coils, a 5" coil is rather large and IMO its a novelty concept. not entirely a need for a coil that large.

aluminum has a higher resistance then copper obviously. depending on your coil parameters, a copper coil will not be good for a 5". its weight would be insane unless you design the motor as a split gap to keep the necessary wind height minimal. copper can limit the impedance choice you want also. d1 for instance in copper with a 5" diameter wont work out nicely. go with aluminum and due to the body, .010 minimum former.
Reply With Quote Quick reply to this message
The Following User Says Thank You to Jeffhulbert50 For This Useful Post:
adulbrich (05-17-2015)
  #3  
Old 05-17-2015, 12:17 AM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default

Quote:
Originally Posted by Jeffhulbert50 View Post
1. pole sleeves are exactly as they sound. a sleeve (tube) of material. sleeve helps visualize that its a solid piece. look at a coil former, notice it has a slit/separation. that's to prevent shorting. the pole sleeve AKA shorting ring/sleeve creates a closed circuit to absorb eddy currents.

2. using a sleeve makes a motor weaker because it makes the gap larger (requires a smaller pole to make room for the sleeve) if the pole needs to be 3.00 OD and the sleeve is .10" thick, you need to shave the pole down to 2.9 thus the gap is "wider"

3. some are aluminum, some are brass, others are copper. each material has its thermal/shorting/cost advantage/disadvantage

4. the supercharge option is almost a one sided bucking magnet. the pole is often the weakest link in magnetic loop. placing a magnet in top of the pole (with matching magnetic poles touching) works to increase the strength by making a secondary loop between the top of the top plate and the pole. the bad portion is increased stray flux since the open pole is rather generous in its flux spread

5. copper on the pole will help in a similar manner that a pole sleeve has. its a shorted material that has the property of magnetic interference/manipulation.

6. as far as coils, a 5" coil is rather large and IMO its a novelty concept. not entirely a need for a coil that large.

7. aluminum has a higher resistance then copper obviously. depending on your coil parameters, a copper coil will not be good for a 5". its weight would be insane unless you design the motor as a split gap to keep the necessary wind height minimal. copper can limit the impedance choice you want also. d1 for instance in copper with a 5" diameter wont work out nicely. go with aluminum and due to the body, .010 minimum former.
First of all, I'd like to thank you very much for your input.

I numbered your paragraphs to make my responses easier to understand:

1. I did not understand the purpose of the slit in the former. I simply thought it was a cost thing. Formers made of cut and bent sheet metal would be cheaper to produce than thin cast tubes. Is eddy current the same as back-EMF? Inf not, how are they different?

2. Ok, so reducing the size of the steel pole piece makes the gap wider, even though you put more metal around it to make up the space. Makes since since the sleeve materials are not magnetic.

3. Thanks for the info. I know I've heard of Aluminum and Copper being used. Brass makes sense since it has a lot of copper in it. Which would be the best if cost was not a factor? Do the materials have their pluses and minuses like everything else seems to have? How do you determine the ideal thickness of the pole sleeve?

4/5. Would neo supercharging or copper shorting ring be better if cost is not a factor?

6. I was thinking that 5" coil because of its thermal power handling capabilities. I want to get a Taramps 30k to power one sub. If you know of any coils that can handle more power daily, I would be more than happy to know!

7. I would like to wire to one ohm nominal, so either dual 2 or dual .5.

I like the idea of dual .5 like my Z, because I can wire 1 ohm for daily and .25 for burps.

However, I have heard that parallel wiring is better than series if both setups wire to the same resistance. Not sure how true it is. My only source is this video: https://www.youtube.com/watch?v=IFFDrWGUDkM

EDIT:

Would you build me a Supergauss neo sub with a 5" coil?? Can you think of any better ideas?
If so, I would really like to talk to you about it
Reply With Quote Quick reply to this message
 
  #4  
Old 05-17-2015, 12:35 AM
Jeffhulbert50's Avatar
Authorized Vendor
 
Activity Longevity
0/20 14/20
Today Posts
0/11 ssss14115
Location: middle of east
Thanks: 65
Thanked 1,756 Times in 1,344 Posts
iTrader: (83)
Feedback Score: 83 reviews
Default

Quote:
Originally Posted by adulbrich View Post
First of all, I'd like to thank you very much for your input.

I numbered your paragraphs to make my responses easier to understand:

1. I did not understand the purpose of the slit in the former. I simply thought it was a cost thing. Formers made of cut and bent sheet metal would be cheaper to produce than thin cast tubes. Is eddy current the same as back-EMF? Inf not, how are they different?

EMF is EMF, the back portion is simply the device creating reversed emf as apposed to induced. short a coil and move it through the gap or try reading impedance when tapping the cone.

the slit is to prevent the coil from turning the former into an inductor

2. Ok, so reducing the size of the steel pole piece makes the gap wider, even though you put more metal around it to make up the space. Makes since since the sleeve materials are not magnetic.

proper modeling would help simulate appropriate amounts. im not sure if a general rule of thumb exists though.


3. Thanks for the info. I know I've heard of Aluminum and Copper being used. Brass makes sense since it has a lot of copper in it. Which would be
the best if cost was not a factor? Do the materials have their pluses and minuses like everything else seems to have? How do you determine the ideal thickness of the pole sleeve?

that's a good question also. faraday law im not 100% on. id guess copper due to its thermal and magnetic conductivity property. downfall being corrosion prevention.

4/5. Would neo supercharging or copper shorting ring be better if cost is not a factor?

id rather put the "charge" into the assembly instead of adding a device. id also do both shorting rings for minimal inductance and better motor

6. I was thinking that 5" coil because of its thermal power handling capabilities. I want to get a Taramps 30k to power one sub. If you know of any coils that can handle more power daily, I would be more than happy to know!

keep in mind, more power is fine and all but eventually your still getting the same cone area X excursion for general output thus keeping a lot of the power from being used properly. 5" coil will limit you to 18s respectively .

7. I would like to wire to one ohm nominal, so either dual 2 or dual .5.

I like the idea of dual .5 like my Z, because I can wire 1 ohm for daily and .25 for burps.

However, I have heard that parallel wiring is better than series if both setups wire to the same resistance. Not sure how true it is. My only source is this video: https://www.youtube.com/watch?v=IFFDrWGUDkM

I prefer a fully parallel setup my self to minimize length of the circuit
EDIT:

Would you build me a Supergauss neo sub with a 5" coil?? Can you think of any better ideas?
If so, I would really like to talk to you about it

supergauss is a play on a bucking system. id find 2 motors to base it off of, tear them down and reassemble with appropriate mods. done deal. was going to try it on my n3's but the weight would have been ~145lbs for one sub lol
Reply With Quote Quick reply to this message
The Following User Says Thank You to Jeffhulbert50 For This Useful Post:
adulbrich (05-17-2015)
  #5  
Old 05-17-2015, 12:49 AM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default

Yea, impedance fluctuates even when you're just talking. It's always jumping around when you measure with a multimeter. I heard about some SQ drivers having one coil that was shorted internally to work as a magnetic brake. You mentioned something similar when we were discussing supergauss subs.

Copper would make sense. Seems like copper is one of the best options when audio is concerned. Didn't even think about corrosion though.

So you'd go shorting rings instead of a reversed neo on the pole tip?

I see what you mean about power. The 5" b2 subs are made in 15's. I would like to do one 15 in 5 cubes net tuned low on the Taramps 30k.

I would like to do a parallel for daily, but then I can't wire lower for burps with my M4a. :shrug:

I have those two N3 motors. They're currently built and I haven't even gotten to use them, lol. I'm hoping to finish my baffle tomorrow. It has been a slow build due to work, track, and homework. Summer is coming in a few weeks, but I've still got another year of highschool

Could you base it off the N3 design and not tear them apart? I know a guy who owns a metal machine shop. He made me a custom intake manifold for my go-kart so I could put a moped fuel injection kit on it for 8th grade science fair. I still have the turbocharger for it. World's smallest turbo, about the size of a soda can. He can do any custom tooling of steel for me at a decent price.
Reply With Quote Quick reply to this message
  #6  
Old 05-17-2015, 01:26 AM
Elite Member
 
Activity Longevity
0/20 14/20
Today Posts
0/11 sssss1085
Location: WY
Thanks: 51
Thanked 164 Times in 129 Posts
iTrader: (23)
Feedback Score: 23 reviews
Default

The oddball quad coil drivers that either short one or two coils or have a solid former are only like that to manipulate qts by lowering qms. When you put copper/brass/alum in the gap it stabilizes the B field, but a shorted coil or solid former does not achieve this.
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
  #7  
Old 05-17-2015, 01:32 AM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default

Quad coils are awesome, but you don't see them often.

I am not very familiar with the significance of total Q. I have seen the spec, but don't understand its importance. All information on the subject would be appreciated
Reply With Quote Quick reply to this message
  #8  
Old 05-01-2016, 01:42 AM
bassfreak's Avatar
Elite Member
 
Activity Longevity
0/20 19/20
Today Posts
0/11 ssssss597
Location: lafayette,la
Thanks: 7
Thanked 33 Times in 29 Posts
iTrader: (0)
Feedback Score: 0 reviews
Default

real big difference in copper and aluminum is one is diamagnetic and has way higher conductivity properties. alum in the gap really wont do very much honestly..

putting a magnets not shielded on hte tyoke is pretty silly and you can throw the FEA out the window because you going to have some terrible flux lines and flux modulation.

you want to fight impedance? best way it take the resonance out of the alignment and driver. transmission lines help stabilize impedance both electrical and acoustically.

i see NO reason for such huge coils and inductance become very unstable and high.
your much better off with a smaller coil and using shorting rings/cooling techniques.

your going about getting loud wrong. by far the cabin and alignment you use are going to affect acoustical output than electrical input.
Reply With Quote Quick reply to this message
The Following User Says Thank You to bassfreak For This Useful Post:
adulbrich (05-01-2016)
  #9  
Old 05-01-2016, 02:02 AM
Jeffhulbert50's Avatar
Authorized Vendor
 
Activity Longevity
0/20 14/20
Today Posts
0/11 ssss14115
Location: middle of east
Thanks: 65
Thanked 1,756 Times in 1,344 Posts
iTrader: (83)
Feedback Score: 83 reviews
Default

threads rolling up on a year old
Reply With Quote Quick reply to this message
  #10  
Old 05-01-2016, 02:21 AM
bassfreak's Avatar
Elite Member
 
Activity Longevity
0/20 19/20
Today Posts
0/11 ssssss597
Location: lafayette,la
Thanks: 7
Thanked 33 Times in 29 Posts
iTrader: (0)
Feedback Score: 0 reviews
Default

Quote:
Originally Posted by Jeffhulbert50 View Post
threads rolling up on a year old
well i went threw it. figured id add to it. it surfaced..
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Tags
damping, impedance, motor, neo, rise

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Car Audio Classifieds! forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Location
Where you live
Level of Car Audio Knowledge
What's your level of car audio?

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
technical help for rca voltage experiment please slowpoke General Car Audio Discussion & Questions 1 11-24-2012 08:44 PM
Technical Help please (with video) dkahns51 General Car Audio Discussion & Questions 0 06-02-2011 10:14 AM
Technical name for eskamo hats?!! mattintc10 Off Topic Chat 22 03-12-2011 02:35 AM
Another question about some technical stuff mattintc10 General Car Audio Discussion & Questions 8 10-03-2010 09:26 PM
Need technical assistance from mechman hazardous0388 General Car Audio Discussion & Questions 0 05-24-2010 11:53 AM

» Amps
A/d/s/
Advent
Alphasonik
Alpine
American Bass
ARC Audio
Atomic
Audio Art
Audio Gods
Audiobahn
Audiocontrol
Audiopipe
Audison
Aura
Autotek
Avionixx
Bazooka
Beyma
Blaupunkt
Boss
Boston Acoustics
Bravox
Cadence
Cascade (CAE)
CDT Audio
Cerwin Vega
Clarion
Clif Designs
Concept
Coustic
Critical Mass
Crossfire
Crunch
DB Drive
DC Audio
DC Power
DEI
Denon
Diabolo
Diamond
Digital Designs
Directed
DLS
Dual
DYnamat
Dynaudio
Earthquake
Eclipse
Elemental Designs
ESX
Eton
Farenheit
Fi Car Audio
Fix My Speaker
Focal
Fusion
Genesis
Ground Zero
Hafler
Helix
Hertz
Hifonics
Hushmat
Image Dynamics
Infinity
Interfire
JBL
Jensen
JL Audio
JVC
Kenwood
Kicker
Knu Konceptz
Kole Audio
Kove Audio
Lanzar
Lightning Audio
Linear Power
MA Audio
Magnat
Marantz
Massive Audio
MB Quart
McIntosh
Memphis
Metra
MMATS
Mobile Authority
Morel
MTX
Nakamichi
Niche Audio
O2 Audio
Ohio Generator
Optima
Orion
Oxygen Audio
OZ Audio
PG Audio
Phase Linear
Phoenix Gold
Pioneer
Polk
Power Acoustik
Powerbass
Powermaster
Precision Power
Profile
Pyle
Pyramid
RadioShack
Rainbow
Rampage
RE AUdio
Rockford Fosgate
Scanspeak
Scosche
Seas
Sony
soundstream
Sparkomatic
SPL Dynamics
Stinger
Sundown Audio
Swiss Audio
Targa
TC Sounds
TREO Engineering
TRU
Tsunami
Ultimate
US Acoustics
US Amps
Velodyne
Vifa
Viper
Visonik
Xtant
Zapco
Zed Audio
Powered by vBadvanced CMPS v3.2.3
Links
Amp Guts
amplifier, amp guts, ampguts, car audio classifieds, speakers and subs for sale with listings of 12 volt sound systems. Security systems for sale for aftermarket car audio equipment with amplifier and amps for sale
Car Audio Forum
car audio forum, moble audio, car stereo, wholesale car audio, 12 volt, with, amplifier, amp, subwoofer, sound quality, buy car audio, and sell automotive stereo systems for cars
Car Audio Sound Quality Forum
Sound QUality science based car audio forum, amplifier, subs and speaker design, fabrication help, sound systems forum, aftermarket car audio website for sound quality.
Car Stereo Forum
DIYMA car audio stereo forum for 12 volt car audio subwoofer and amplifier systems that have sound quality with wholesale car audio products.


All times are GMT -5. The time now is 05:02 AM.


Powered by vBulletin
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.6.0
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.