experiences with ESL directivity? - Page 8 - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

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 12th June 2010, 09:15 PM   #71
diyAudio Member
 
kavermei's Avatar
 
Join Date: Jan 2005
Location: Lokeren, Belgium
Send a message via MSN to kavermei
Hi Alex,

the AES article's setup is comparable to the ladder in Fig. 2. The author uses RCR T-sections, so he has a resistor in front of the middle section too. But I don't think it'll make much difference.

Kenneth
__________________
Never send a human to do a machine's job. --Agent Smith
  Reply With Quote
Old 12th June 2010, 10:36 PM   #72
diyAudio Member
 
bolserst's Avatar
 
Join Date: Jun 2005
Location: Fort Worth, Texas
Quote:
Originally Posted by alexberg View Post
In Frank Verwaal papers there is a table (Part #2 p.80) with the RC filters to be used for linear frequency response. Next figures show the implementation of the idea.
So, am I right, assuming:
1) for different stip widths the table and individual resistors per stip (Fig.#1) is applicable.
2) if the ladder structure is employed (Fig.#2) then all the resistors are equal, strip width are all the same and bolsert's spreadheet is applicable, as well as the AES article we discussed.
Hello Alexberg,

If you use individual resistors to feed each strip (Fig. #1) you will need increasing resistor values for each section to obtain a flat response. The resistor values shown in Frank's table are specific to his design. ie number and size of each segment, capacitance of each segment, target bandwidth for flat response.

As kavermei already mentioned, the ladder network (Fig. #2) with equal sectional widths and resistors is similar to the symmetric layout analyzed in the AES paper. All that is missing is the initial feed resistor.

The spreadsheet gives values for the asymmetric layout which the AES paper uses when deriving most of the equations. I modified your (Fig. #2) to show what feed layout should be used for the section sizes and feed resistances(R) calculated in the spreadsheet. I now realize I should have included it in the spreadsheet documentation since not everybody who uses the spreadsheet will have a copy of the AES reference paper.

Note that the resistor feeding the first section is half the value of the rest of the resistors in the ladder network. In practice, this resistor can be put on the primary side of the transformer where it can also help with saturation control. Just take the value (R/2) and divide by the square of the step-up ratio. Be advised that you will probably have to tweak the value of this first resistor to compensate for other factors not considered in the HF response as mentioned on the directions tab of the spreadsheet.

3) Transformer leakage inductance behavior at HF is ignored
4) Section to section capacitive coupling is ignored
5) HF loss due to the inertia of the diaphragm and/or the inertia of air in the holes in the stators is ignored.


If anybody is interested, I can post the ratios or factors to apply to the spreadsheet values for feed resistance and sectional capacitance if you want to use a symmetric layout. Let me know. Or, perhaps, a version 2 of the spreadsheet with separate tabs for symmetric and asymmetric configurations.
Attached Images
File Type: gif ESL_segm.gif (36.7 KB, 205 views)
  Reply With Quote
Old 13th June 2010, 12:03 AM   #73
Few is offline Few  United States
diyAudio Member
 
Join Date: Apr 2004
Location: Maine, USA
Quote:
If anybody is interested, I can post the ratios or factors to apply to the spreadsheet values for feed resistance and sectional capacitance if you want to use a symmetric layout. Let me know.
I'm planning on a symmetric layout so a spreadsheet version for that would be great! Thanks for the generous offer.

Few
  Reply With Quote
Old 13th June 2010, 02:41 AM   #74
diyAudio Member
 
chinsettawong's Avatar
 
Join Date: Jun 2006
Hi Bolserst,

Thanks for sharing the spreadsheet.

Wachara C.
  Reply With Quote
Old 13th June 2010, 07:13 AM   #75
diyAudio Member
 
kavermei's Avatar
 
Join Date: Jan 2005
Location: Lokeren, Belgium
Send a message via MSN to kavermei
Hi,

Quote:
Originally Posted by bolserst View Post
[...]In practice, this resistor can be put on the primary side of the transformer where it can also help with saturation control. Just take the value (R/2) and divide by the square of the step-up ratio.[...]
I would argue that it should be kept in the secondary circuit, since in the primary it will cause distortion.

I think it's better to control saturation by using a line-level highpass filter.

Kenneth
__________________
Never send a human to do a machine's job. --Agent Smith
  Reply With Quote
Old 13th June 2010, 09:16 AM   #76
diyAudio Member
 
alexberg's Avatar
 
Join Date: Oct 2009
Default Stripes

Thanks a lot!
That's exactly what I thought, but it does not hurt to ask.
With the best regards,
Alex
  Reply With Quote
Old 13th June 2010, 02:25 PM   #77
diyAudio Member
 
Join Date: Oct 2009
Location: Hamburg
Having now owned Quad ESL 57's and Quad ESL 63's I have to say quads combination of filter and delay line in the ESL 63 is very impressive, for improving the treble dispersion. Unless you play with a pair of ESL 63's for a while you would not realize how good they are at treble dispersion because the bass is still very directive.
  Reply With Quote
Old 13th June 2010, 06:47 PM   #78
diyAudio Member
 
bolserst's Avatar
 
Join Date: Jun 2005
Location: Fort Worth, Texas
Quote:
Originally Posted by kavermei View Post
Quote:
Originally Posted by bolserst
[...]In practice, this resistor can be put on the primary side of the transformer where it can also help with saturation control. Just take the value (R/2) and divide by the square of the step-up ratio.[...]
Hi,

I would argue that it should be kept in the secondary circuit, since in the primary it will cause distortion.

I think it's better to control saturation by using a line-level highpass filter.

Kenneth
I agree, from a distortion standpoint you want to minimize the resistance in the primary circuit. For practical reasons, I usually keep a small primary series resistance to protect the amplifier just in case something unexpected happens or the filter network is accidently bypassed. Any additional resistance needed is put in the secondary circuit. I found that as long as the primary series resistance is < 2ohm the distortion increase is pretty minimal for typical M6 core material.

The reason I mentioned it was to point out that even if the first feed resistor doesn't seem to be in the circuit(on the secondary side connected to the first section) it might have been moved to the primary side where its function is not as obvious.

For those unfamiliar with the source of distortion kavermei is talking about, this post explains it a bit more.
Step-up transformer design

Also, for a visual aid, geraldfryjr had posted some plots showing the input voltage and distorted current waveforms for the primary circuit.
Step-up transformer design

Last edited by bolserst; 13th June 2010 at 07:14 PM.
  Reply With Quote
Old 13th June 2010, 06:49 PM   #79
diyAudio Member
 
bolserst's Avatar
 
Join Date: Jun 2005
Location: Fort Worth, Texas
Quote:
Originally Posted by Few View Post
I'm planning on a symmetric layout so a spreadsheet version for that would be great!
I should have time to post an updated spreadsheet in a few days which includes the symmetric layout.
  Reply With Quote
Old 13th June 2010, 08:43 PM   #80
diyAudio Member
 
kavermei's Avatar
 
Join Date: Jan 2005
Location: Lokeren, Belgium
Send a message via MSN to kavermei
Yes, I agree, 2 ohm should be okay.

Thanks for the spreadsheet, it's very handy!

Kenneth
__________________
Never send a human to do a machine's job. --Agent Smith
  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
Constant Directivity Horn EQ Horizons Multi-Way 4 19th December 2008 11:41 AM
Constant directivity EQ Saurav Multi-Way 11 19th May 2008 02:41 AM
Constant directivity horn - or waveguide? hasselbaink Multi-Way 6 1st April 2008 01:24 PM
A question on directivity swak Multi-Way 18 31st July 2005 03:03 PM
Open baffles and directivity Yuihb Multi-Way 18 27th February 2004 08:22 PM


New To Site? Need Help?

All times are GMT. The time now is 12:43 PM.


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