Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

To Heil AMT or not to Heil at 0, that is the question?
To Heil AMT or not to Heil at 0, that is the question?
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 January 2019, 02:07 AM   #31
djn is offline djn  United States
diyAudio Member
 
djn's Avatar
 
Join Date: Oct 2004
Location: Albuquerque, New Mexico
Mine are from the 70s with origanal diaphragm. Still the very best tweeter I've ever heard. To my ear of course. I cross over from the Edgar horns to the Heil at 5khz. To my ear the Heil sound thin below 5khz but none of my friends agree.
Attached Images
File Type: jpg 20151128_223826.jpg (471.8 KB, 234 views)
  Reply With Quote
Old 12th January 2019, 02:24 AM   #32
Robh3606 is offline Robh3606  United States
diyAudio Member
 
Robh3606's Avatar
 
Join Date: Nov 2002
Location: Destiny
Quote:
To my ear the Heil sound thin below 5khz but none of my friends agree.
They do have rising response that shelves with the peak at 5K so I can see that.

Rob
__________________
"I could be arguing in my spare time"
  Reply With Quote
Old 12th January 2019, 03:37 AM   #33
puppet is offline puppet  United States
diyAudio Member
 
Join Date: Dec 2011
Location: The Dells, WI
According to a german article that 5k spike is the result of sound waves leaking between the ends of the focus plates and the plastic cover.

Their fix was to fit a felt "belt" from the diaphragm slot, over the focus plate, around the plastic housing to the other side, returning on the back focus plate to the backside diaphragm slot. This of course did half the unit and was repeated on the opposite half.


Hifi-Selbstbau - ESS AMT-1 Air-Motion-Transformer
  Reply With Quote
Old 12th January 2019, 03:46 AM   #34
puppet is offline puppet  United States
diyAudio Member
 
Join Date: Dec 2011
Location: The Dells, WI
This is their modification sheet.
Attached Files
File Type: pdf ess_amt1_modifikation.pdf (790.7 KB, 85 views)
  Reply With Quote
Old 12th January 2019, 04:16 AM   #35
ICG is offline ICG  Germany
diyAudio Member
 
ICG's Avatar
 
Join Date: Jul 2007
Location: I had a Déjà Moo - I've seen that BS before!
Quote:
Originally Posted by DaveFred View Post
Normally tweeters in free air are a bad idea.

Why isn't diffraction a big issue with this design?
There are two reasons.

Firstly, the big AMTs got, unlike domes and cones, a very narrow vertical dispersion. They simply don't hit as much as other dipoles or 360° speakers. That leads to reflections reaching the ear within a shorter period of time, which often is heard as more precise. The reflections (especally on dipoles) usually make speakers sound broader, more depth, 'air-ier', and that's pretty much dependent on the enviroment, the reflecting surfaces (furniture, walls, windows) and absorbing characteristics (courtains, sofa, bed, pillows etc). So if you aren't satisfied with the room impression, it will change much more than with 'just' direct radiating speakers to different speaker positions and angles.

Secondly, most drivers got a much different dispersion over the frequency, they 'beam', get narrower. For dipoles with cones or dome drivers that usually means, the sound energy balance in the room is quite non-linear and any reflection will sound different, depending on where from they come and what and how much reflected/absorbed they are. That isn't a good thing because the reflections actually do add up to the preceived tonal balance. For cones i.e. the backwards radiated sound differs a lot from the forward radiated sound, even without the reflections, because the magnet, basket and spider are in the way, combined with the beaming towards higher frequencies/very broad dispersion at the lower end, the sound gets 'muddier'.
At the big AMT you don't have any of these, the backwards dispersed sound is identical in response to the front-wise (except for the phase) and they have still exactly the same dispersion, a quite good horizontal dispersion and same narrow vertical one aswell.

Quote:
Originally Posted by DaveFred View Post
Is the Great Heil ever used in a monopole fashion on a baffle?
Yes, there were some which got an absorption chamber behind them (i.e. the ESS amt-bookshelf) and ofcourse there are still the smaller AMT monopoles. If you want to use the big dipoles, you'll want the dipole characteristics, otherwise you'd be better off to just buy different ones which don't pose that much needed effort and time in experiments on how to tame the back energy in the way you want them to sound.

Quote:
Originally Posted by DaveFred View Post
Or is monopole a waste of this gem?
Yes, that's pretty much sums uip what I wanted to say.
__________________
I had a Déjà Moo - I've seen that BS before!
  Reply With Quote
Old 12th January 2019, 04:48 AM   #36
ICG is offline ICG  Germany
diyAudio Member
 
ICG's Avatar
 
Join Date: Jul 2007
Location: I had a Déjà Moo - I've seen that BS before!
Quote:
Originally Posted by puppet View Post
This is their modification sheet.
The ESS AMT-1 was manufactured over a long time and was modified a lot and without any note or explanation on how to recognize it. The membrane units are often not compatible, differ in thickness, membrane material, response and spl. That means, they can actually sound a lot different. So generally, you'll want to buy them in pairs or matched. You'll also want to measure them in response/spl, distortion, decay and impedance. Some differences can be compensated for by developing/modifying the crossover for each one (and don't forget to mark which xo is for which AMT!).

The tape trick is well known and cannot harm in any way, even if you got a different version which does not have that problem. And since costs practically nothing, it's a very good idea to do it.

The foam on the back side is different though. You'll have to experiment a lot with it because of the nature of absorption of sound, it will change the tonal balance of the (quieter but still audible) backwards radiated sound. And while it does improve the mechanical resonance around 650-900Hz (depending on which model, membrane unit slot and membrane unit you've got, some got several, lesser resonances, some got different frequencies), I'm not very thrilled by the 'construction' of the foam part. See, the problem is, in the middle the sound has a shorter distance till it leaves the foam, near the magnets the sound runs through a lot more foam than in the middle, that means, it filters there a lot more and lower frequencies than in the middle, that means, the response will be much different, especally under angles. I did not measure it how relevant it is but it's definitely not enough to absorb all the back energy. The easy solution would be, if you want to use that foam at all, to use a wedge of a circle (don't know how to describe it, like a piece of a cake with the front angle cut off). IMHO it's much better to just try different speaker positions to keep the advantage of the dipole or just use different AMTs or experiment with the reflecting back surfaces.
__________________
I had a Déjà Moo - I've seen that BS before!
  Reply With Quote
Old 12th January 2019, 04:52 AM   #37
kec is offline kec  United States
diyAudio Member
 
kec's Avatar
 
Join Date: Mar 2001
Location: SoCal
Good info ICG
__________________
MSI E350IS mITX > Foobar > SPDIF > Denon A7100 preamp > Crown XLS1000 > ?
  Reply With Quote
Old 12th January 2019, 05:09 AM   #38
DaveFred is offline DaveFred  Canada
diyAudio Member
 
Join Date: Jan 2018
Quote:
Originally Posted by puppet View Post
This is their modification sheet.
Do you understand this?

The cause of the ripple of our ESS AMT-1 at 5 kHz was the sound leakage at the end of the Disc packs (red arrow) over the entire height of the slot. Once you have the with textile adhesive tape This ripple was fixed.
Cause is probably a part of the radiated from the outer lateral regions of the membrane Sound that gets into the inner workings of the AMT-1. Unfortunately, you can not open the chassis as it is in the
Image is shown, because then you should also bring absorption material in the outer areas(pink hatched area).
Another irregularity occurs at 12 kHz. This could be due to an absorbent pad
be linearized the "disk pack". As a "combination measure" we therefore have the disk set taped with d-c-fix® velor, in total height (= 138 mm) from the beginning of the "closed" Disc packs to the back (= 264 mm long). Here then the side part was also complete pasted over. The effect for the break-in at 12 kHz was very low, but this break-in only occurs Axle up. With stronger absorption on the disk pack, the range was> 7 kHz too heavily damped.
We strongly assume that even newer versions of the ESS AMT-1 still have this weakness at 5 kHz and benefit from this conversion.
To dampen the mechanical resonance at 870 Hz, we also recommend using one Basotect triangular block (height 138 mm, base area s.u.) complete the rear triangle fill. The Basotect block increases the mechanical losses and thus dampens the Resonance frequency. In addition, the radiation is reduced to the rear, which is too low Wall clearances to the rear is usually very beneficial.
  Reply With Quote
Old 12th January 2019, 12:45 PM   #39
Cask05 is offline Cask05  United States
diyAudio Member
 
Cask05's Avatar
 
Join Date: Nov 2007
Location: Arlington, TX
I personally see a lot of inaccurate or misleading information regarding what you'll get with a new pair of AMT-1s from ESS (California) in the last couple of pages. While some of the historical information here might be interesting (i.e., thread drift), understand that much of what I've read is not accurate or not applicable to the present AMT-1 based on measurements of new units. Many of the arguments above have no material relevance to the drivers mentioned by the OP. Try a pair for yourself rather than suffering the angst from "expert opinion".

I've found that the ESS AMT-1 enables excellent configurations for 2-way loudspeakers using a DSP crossover with first order (IIR) filters without the type of phase/group delay growth that you see with typical higher order IIR filters, especially when looking at the combined step response. The AMT-1 transient response is second to none that I've measured or listened to. I would assume that DSP with FIR filtering will take this combined performance to an even higher level.

I can recommend that the AMT-1s can be used down to their stated 800 crossover point (or even slightly lower) without issues of significant distortion or loss of polar control...and the sound is superb.

While most here will opt for a direct radiating woofer in a vented cabinet, I can highly recommend a fully horn loaded Belle or La Scala type bass bin as improved choices--which will give you coverage control down to below 100 Hz (i.e., below your listening room's Schroeder frequency). The tightness and cleanness of sound and quality of the "tinkles" is outstanding, subjectively coinciding with the aforementioned good measurement results.

Chris
  Reply With Quote
Old 12th January 2019, 02:53 PM   #40
puppet is offline puppet  United States
diyAudio Member
 
Join Date: Dec 2011
Location: The Dells, WI
@davefred

No, I don't speak the language but the text can be copied to a translator easy enough.


I have to wonder why, except to pretty them up, that a simple welded plate across the angle iron (top and bottom) wasn't used thus ditching the black "resonance" chamber created by the cover. Actually, you could drill a hole dead center on each cover and shoot "great stuff " in there.

Last edited by puppet; 12th January 2019 at 02:56 PM.
  Reply With Quote

Reply


To Heil AMT or not to Heil at 0, that is the question?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
ESS Heil AMT Question maLx Planars & Exotics 16 25th June 2018 05:20 AM
ESS AMT Heil Monitors with Heil Tweeter erik777 Planars & Exotics 3 4th November 2014 09:37 PM
HEIL amt & audax midrange (open baffle question) bytelight Multi-Way 3 9th February 2012 09:43 AM
Heil XO Ang Planars & Exotics 2 9th April 2007 09:47 PM
Heil help whatsnext Planars & Exotics 6 22nd September 2006 07:22 PM


New To Site? Need Help?

All times are GMT. The time now is 08:54 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki