Heil with a JBL woofer

[Robh3606]

Not sure which direction I am going to go either full up passive or an active with passive compensation on the Heil to help flatten the response. Have to be very careful with the impedance of the Heil driver combining with a passive network. Took a couple of measurements to get started of the raw driver, got an odd notch in response, repeated the measurement and it didn't go away. Have to try off axis but varying distance had no effect nor did temporarily using a baffle to keep the back-wave out of the measurement.. I did a quick 18Db network with a 5 K notch it's not bad at all. With the losses in the network it's close to the 91/92 sensitivity of either a 128H-1 or a 2214H.

Rob:)

[Mr. Widget]

That actually looks shockingly good. I wouldn't be too worried about the narrow notch at 6800Hz. I bet it would be hard to notice it.

I assume that is on axis. Please post more!


Widget

[toddalin]

I get the same/similar notch. This is my point where I said that you need an RTA for the best placement.

In my system, the depth and bandwidth of the notch is directly related to where the Heil sits in relation to the 2251J cabinet that it sits on. The closer the heil is to the front of the cabinet, the deeper and tighter the notch. I get the best integration with the Heil as rearward as possible. Perhaps this is the best time alignment with the 2251, but to my eye, it looks like it would sit behind the audio plane of the 2251 in this position.

I had attributed this to the interfacing/interference with the 2251J, but am now thinking that this has to do with a reflection, or lack thereof, from the cabinet that it is sitting on.

BTW, Widget is correct that it is difficult to actually hear the notch. OTOH, it makes it harder to hear tones centered at the notch (e.g., some percussion). These are told by listening to other speakers with other notches/peaks (e.g., the L200/300s)

http://www.audioheritage.org/photopost/data//500/medium/DSC_00011.JPG

[Earl K]

Very Cool!

It's great to finally see some pro measurements of these large Heils.

Woody's broadcast post was exceedingly attractive ( but alas, I need to sell off gear > not buy more ).

Still, it's all a bit haunting due to long cherished memories of listening to my aunts large AMT's .

I agree that some le14's should be a nice match-up.

:)

[toddalin]

OK I did some testing and included some photos. My problem is an interaction with the midrange speaker. When I turn off the midrange, the tweeter spectrum is pretty much unchanged moving from the front to the back.

I am not getting the dip that Rob notes because I am using this in a 3-way and the tweeter is crossed over over to take advantage of this dip to produce 2nd order slope with a 1st order cap.

Tweeter forward:

http://www.audioheritage.org/photopost/data//500/medium/DSC_00019.JPG

Forward spectrum:
http://www.audioheritage.org/photopost/data//500/medium/DSC_00025.JPG

Tweeter rearward:

http://www.audioheritage.org/photopost/data//500/medium/DSC_00037.JPG

Rearward spectrum:
http://www.audioheritage.org/photopost/data//500/medium/DSC_00044.JPG

Spectrum for the tweeter without midrange:

http://www.audioheritage.org/photopost/data//500/medium/DSC_000110.JPG

[Robh3606]

So today I tried an Active approach with EQ. The first was trying to use the ESS Active and it just didn't work as the slopes were too shallow. I had to add poles which I suspected it just was not worth it using the ESS I would have been better off just going passive.

Round 2 Active was using one on my JBL M552 24dB L/R and this worked out to be the easiest solution as it was almost identical to the passive network solution with a modified lower Q notch filter.

Hello Widget

Yes that's on axis I will post step response and waterfall.

Hello Earl

I looked around for something like a CLIO measurement and didn't find one? Odd not like these are new kids on the block!

Hello Toddalin

Thanks for confirming the notch glad to know it's not unique too my driver. What is the resolution on the RTA are those 3db or10db notches?

[toddalin]

S

Hello Toddalin

Thanks for confirming the notch glad to know it's not unique too my driver. What is the resolution on the RTA are those 3db or10db notches?


It's 2.5 dB between the dotted lines. The full scale is set at 15 dB.

[Robh3606]

Hello Earl

Found some!

Rob:)

[Earl K]

Thanks Rob!

With my high-school German being pretty rusty these days, Google Translate helped fill in the large blanks.

:)

[grumpy]

Indeed.

> The original among the air-motion transformers, the AMT-1, is still being produced by ESS. The large and heavyweight tweeter is designed for free placement on a loudspeaker cabinet. Thanks to its dipole design, it radiates identically to the front and rear, thus promoting the diffuse sound in the room and, ultimately, the spaciousness in the sound image.
Characteristic for a dipole tweeter,
the frequency response does not shine with perfect linearity, but with an extremely broadband appearance and enormously high efficiency: 100 dB are available at 2.83 volts (equivalent to 1 watt to s ohms) if the AMT-1 at least 2,000 hertz is used. He also creates sovereign 1.000 Hertz. For this application, he is trimmed by means of a high-frequency filter to the still very respectable 95 dB available below 2,000 hertz.
That was not always the case: in 5/2007 we tested this tweeter and diagnosed readiness at the earliest from 1.5 kilohertz. The frequency response was a bit more linear at the time, but there was a massive resonance of the membrane film at 1,000 hertz, and the distortion was a good deal higher. Obviously, almost 50 years after the invention of this tartan, ESS continues to incorporate improvements.
Currently, the AMT-1 shines with outstanding low distortion, and the film resonance is now located a full octave lower.

[toddalin]

Indeed.

> The original among the air-motion transformers, the AMT-1, is still being produced by ESS. The large and heavyweight tweeter is designed for free placement on a loudspeaker cabinet. Thanks to its dipole design, it radiates identically to the front and rear, thus promoting the diffuse sound in the room and, ultimately, the spaciousness in the sound image.


No Grumpy, this is wrong.

Just as with a cone speaker, there is a positive and negative phase and care must be used integrating the Heil with the next lower driver.

Also, while free placement is possible, time alignment becomes very important to avoid dips/drop-outs.

[Earl K]

No Grumpy, this is wrong.

Just as with a cone speaker, there is a positive and negative phase and care must be used integrating the Heil with the next lower driver.

Also, while free placement is possible, time alignment becomes very important to avoid dips/drop-outs.

Todd,

Grumpy merely posted some of the German to English translation taken from the pdf file that Rob had previously posted.

Clearly the Google phrase "free placement" twigged a reaction ( though I believe the phrase was merely an awkward translation for "free-standing" .

Your concerns are all still very valid when it comes to achieving the proper integration of these units ( especially with mono-pole drivers ).

From this pic it would appear you have some response/diffraction issues ? with your 2251 ( a somewhat similar predicament faced by Bill Shenefelt in the distant past > HERE! (http://www.audioheritage.org/vbulletin/showthread.php?15666-Homebrew-4343&highlight=) ;

http://www.audioheritage.org/photopost/data//500/medium/DSC_00044.JPG

[toddalin]

Todd,

Grumpy merely posted some of the German to English translation taken from the pdf file that Rob had previously posted.

Clearly the Google phrase "free placement" twigged a reaction ( though I believe the phrase was merely an awkward translation for "free-standing" .

Your concerns are still very valid when it comes to achieving the proper integration of these units with mono-pole drivers.

From this pic it would appear you have some response/diffraction issues ? with your 2251 ( a somewhat similar predicament faced by Bill Shenefelt in the distant past > HERE! (http://www.audioheritage.org/vbulletin/showthread.php?15666-Homebrew-4343&highlight=) ;

http://www.audioheritage.org/photopost/data//500/medium/DSC_00044.JPG

I tweak these crossovers on a regular basis. Tweak, listen, listen, listen, tweak, repeat.

Sometime the tweaks go better than others. For that photo, I had too much roll off at the top of the 2251. It has been corrected and when I get the parts soldered back (iron gave out and a new one is one the way), I'll repost. As I noted, the 2251J is not without it's "characteristics" and it takes lots of parts substitution to get them as good as they can be.

...But I still expect a certain amount of dip in that area.

When I do post a video, the difference between these and the L300s is very notable, especially in the vocal range.

[grumpy]

Lol. No worries from me. I should have been more clear that my post was simply a cut&paste job with Google Translator being the sole editor (for better or worse). Hoping to have some time with these over the upcoming holidays :)

[Earl K]

For those who might be interested;

Using RobH's Heil files ( downloaded from above ) then traced and turned into .frd + .zma files ( & then the same done to info taken from JBL's 2206H product brochure )
here's a 1400hz crossover design that uses the mentioned drivers.

Clearly I have taken much inspiration from Rob's previously posted hi-pass work.

http://www.audioheritage.org/photopost/data//500/Heil_JBL2206H_.png


I can post the XSim file if anyone has an interest in pursuing this more seriously.

:)

[Robh3606]

Hello Earl

That looks good! That would be a great combo nothing like a 12 on steroids!

Rob:)

[Earl K]

Hello Earl

That looks good! That would be a great combo nothing like a 12 on steroids!

Rob:)

Thanks Rob!

:)

[Earl K]

Hi Rob,

Have you run any distortion measurements on your AMTs to see how low they can go ( before needing to be crossed out to a woofer )?

Can they do 750-800hz ( with a 3-pole network ) ?

:)

[Robh3606]

Hello Earl

Not sure if I did sine or impulse will tale a look. I used the ESS schematics as a reference. They used 18 dB networks in the AMT look at the schematics posted in the General Audio Forum also take a look at the link. Either way when I rerun them I will do a sine sweep to see what's up.

Rob:)

https://essspeakers.store/collections/speakers/products/amt-limited-edition-pair

[Wallacefl]

I wonder how the Heil would respond in a sealed midrange style enclosure ? ESS used to make a model 1B Bookshelf that looks interesting.

[Wallacefl]

OK...I have not posted on the site very often but have been a JBL owner for years. Right now I have some 123a black cones from a L-88 and should like to try the ESS Heils as a mid-tweeter from 1200 hz. The old S70 Alpha has a crossover for the 123a that may be ok as as a start. As to your 18db for the tweeter...how was this derived as the values of components makes acquisition hard? I have no measuring equipment and generally copy others and/or use their guidance. Appreciate your input....

[Earl K]

OK...I have not posted on the site very often but have been a JBL owner for years. Right now I have some 123a black cones from a L-88 and should like to try the ESS Heils as a mid-tweeter from 1200 hz. The old S70 Alpha has a crossover for the 123a that may be ok as as a start. As to your 18db for the tweeter...how was this derived as the values of components makes acquisition hard? I have no measuring equipment and generally copy others and/or use their guidance. Appreciate your input....

What's needed ( from someone owning those woofers ) is a 1 meter, on-axis response measurement ( of the JBL 123 > black cone ) working in a large enclosure ( say 4cu' ) .

No custom crossover can be designed without employing a good response measurement ( & still be considered even half accurate ).

Those are the hard facts.

The HiPass can easily be 2-pole ( 12 db per octave ) with the choice of a higher crossover point ( say > 1500 hz ).

Values ( of the passive crossover parts ) can be massaged to what's available to purchase from the regular suppliers.

:)

[Earl K]

I wonder how the Heil would respond in a sealed midrange style enclosure ? ESS used to make a model 1B Bookshelf that looks interesting.

This is a recent response measurement ( done by JavadS. ) of the big Heil ( as a monopole & also as a regular dipole )

83080

One can see that ( with very minimal response penalty ) one could encase the back of the AMT within a mid-range enclosure ( sealed sono-tube for example ).

:)

[toddalin]

I've devised a "band aid" (pun intended) for the 5kHz suck-out. :applaud:

Take an engineering scale and stand it vertically with one of the three points touching the Heil right at its centerpoint on the forward face. Voila!

Now to determine the optimum size and make a stand to make something like this work. :hmm:

Edit: Ordered a length of triangular 1" clear acrylic. This is the same dimensions of an engineering scale, though the scales do have a very specialized shape. We'll see.

[Robh3606]

Finally got a change to build up the network. I updated the network added a .33 Ohm series resistor with the inductor and changed the value to .075Mh. The added resistance altered the Q of the notch and broadened it and shifted it down a bit. It measures well in an actual vs. predicted comparison.

Rob:)

[Mr. Widget]

That is remarkably close for the predicted vs. measured!

I don’t believe in listening to speakers via YouTube and I also don’t believe in listening to them via plots. That said, do they sound a bit bright? Have you had a chance to audition them?


Widget

[Robh3606]

That is remarkably close for the predicted vs. measured!

Hello Widget

Well that just shows you how good that software is. I swear by it! The funny thing is every time I have had an issue its been me. So I have learned to start looking for where I screwed up if I don't get a reasonable match.


I have not actually listened yet. I don't have any boxes built yet but I am planning on dropping one on top of one of my Array bass cabinets to see how it sounds. I don't expect it to sound bright. There is a significant drop in the top octave when you move off axis. In the vertical it is really significant as bad as the 2405 so you really need to have these at ear height. Take a look at the German magazine measurements 30 degrees off axis. I should really just do a set of off axis measurements but without the cabinets??


If you look at the on axis for the Array its a bit hot up there. I am hoping/expecting it will work out the same way. That said I think the power response will be OK because of the roll-off but I am used to horns not di-poles so I may be in for a bit of a surprise. I expect the backwave to really open them up so to speak just like some systems with rear tweeters.

If I get time I will try them out today or at least during the week after work. Let you know how it goes!

Rob:)

[toddalin]

I, for one, would like to hear a YouTube video when done. Preferably Tin Pan Alley (Stevie Ray Vaughn) that people at AK use for demo purposes.

I've made some recent revisions to my crossover since making this one (increased cap on Heil from 9.2 to 12 mfd to play a bit lower and decreased cap on mid from 10 to 9.2 mfd to play a bit higher), but it is not that different.

This is the most recent video of the Ethyl Mermans and includes my wedges. Again, no sub, eq, or digital processing is used here (Pure Direct). BTW, the wedges, like my 075 slant plates, create a "semi off-axis" response on axis.


https://youtu.be/cO8T6R2WhTE

[1audiohack]

I don’t believe in listening to speakers via YouTube...
Widget

Yeah what’s to stop anyone from just using line out for the audio feed?

“! Check this out!! Single Jensen 6X9 triaxial equals JBL Everest!!”

It has to be true! I saw (and heard) it on youtube.

Also agree, nice work Rob!

Barry.

[toddalin]

You can tell a lot from a well recorded YouTube video. You really think that Rob would do that? :blink:

[1audiohack]

Todd I didn’t mean to be contrary to your request and I don’t mean to infer that Rob would pull a stunt like that either.

While a video of horseback riding or driving a sports car may be entertaining and even instructive I personally find listening to a sound system that is recorded by some other system and then rendered by still another system simply unreliable as evidence and un-immersive as an audio experience.

Sorry to dilute the topic of this thread. :(

Barry.

[Robh3606]

I don’t mean to infer that Rob would pull a stunt like that either.

Hello Bary

I didn't think that at all as a matter of fact that went right over my head I just figured the idea was I wouldn't do a video. Which I won't I agree with you and Widget. Well back to the thread.

Been playing with CLIO and did a series of -40 to 40 degree measurements in 10 degree increments so not high resolution at all but still interesting. Look at whats happening at 10K! Bizarre to say the least really prominent off axis lobes then it behaves as expected. 20k the directivity just collapses to flashlight!

Rob:)

[toddalin]

The problem is that, outside of eq, if you pull the 10+KHz peak down to a reasonable level, you pull down everything, including the trough, and you end up with a "dark cloud." (In fact, I think that this may be what a lot of people are hearing (not hearing) when they say that the ESS AMT1 lacks midrange..., a very common complaint.) The wedge takes care of this.

The alternative (BTDT) is to use a small value inductor in series with the Heil and a by-pass resistor on the inductor, and this has been done by others too. I prefer the wedge.

[Robh3606]

Hello Toddallin


The problem is that, outside of eq, if you pull the 10+KHz peak down to a reasonable level, you pull down everything, including the trough, and you end up with a "dark cloud."

Yeah I agree you can't fix directivity issues with EQ or crossover mods. They are what they are just hope the lobbing isn't to audible fortunately up at 10k it may be desirable to splash the room sound more open. They are not all that high just 3db.


(In fact, I think that this may be what a lot of people are hearing (not hearing) when they say that the ESS AMT1 lacks midrange..., a very common complaint.) The wedge takes care of this.

Are you not using a 10" mid crossed at 5K. How does the wedge take care of it? I can see it doing something above 5k but not affecting the mid range.


Rob:)

[toddalin]

Hello Toddallin



Yeah I agree you can't fix directivity issues with EQ or crossover mods. They are what they are just hope the lobbing isn't to audible fortunately up at 10k it may be desirable to splash the room sound more open. They are not all that high just 3db.



Are you not using a 10" mid crossed at 5K. How does the wedge take care of it? I can see it doing something above 5k but not affecting the mid range.


Rob:)


The 2251J 10" actually crosses over ~2,500 Hz and peters from there. It doesn't like to go smoothly to 5KHz, or maybe even 4KHz. :blink: This is where it's dip lies before it increases in dB.

I first tried to address this at crossover to the 10" to get it up above the Heil's dip..., and could get it pretty flat, but it cost way too many dB, especially when used with a 2241H. So we take advantage of the dip in the 10" to further the crossover's reduction.

Then dip in the Heil would not let it meet the 10". Ergo, the problem. I then tried to address it through crossover to the Heil, but pushing it lower didn't help because I still needed to turn down the peak, and this still reduced everything it was reproducing.

[Robh3606]

Hello Widget

Well have Steely Dan Everything Must Go Pixeleen on with my Le-14H-3 base from my Arrays and it's not too bright. I am at a disadvantage have to listen in mono to summed stereo so not ideal. It's really weird. I can walk around and hear speaker from behind and it seems like it doesn't loose the balance. As a stereo pair it should cover the whole room. Very open sounding even in mono. Now I have to build some boxes!

Rob:)

[Mr. Widget]

Very cool... keep it coming!


Widget

[Robh3606]

I dug up some old boxes I had in storage 2.2 Cubic ft tuned to 28Hz and pulled out my pair of 121A's and dropped them in. Took a look at the alignment in Bass Box Pro and not ideal but not bad either. Little bit of an upgrade from 128H which would have needed a bigger box for the same F3. I forgot these things are beasts! Got both my filters built have to get then up and running tomorrow. Boxes are a bit beat up but sound and nothing a coat of paint cant fix. Can't wait to see what a stereo pair sounds like.

Rob:)

[Mr. Widget]

Sounds exciting... keep us posted.
I received some beautiful veneer and rolled it out. Will be getting back into the DYI scene soon myself! :bouncy:


Widget

[Robh3606]

Hello Widget

OK spill! What do you have up your sleeve? Your last cabinets you sold were gorgeous can't wait to see what you are working on!

Rob:)

[Mr. Widget]

No need to mess up your thread. I’ll start a new thread when the project gets started for real.


Widget

[Robh3606]

I have them up and running and after listening to them for a while I can see why people really like them. The combo with the 121A's is a real keeper. Listening to Santana Abraxis, Steeley Dan, Lumineers, Alan Parsons, Lord, Emilly Haines, Lone Below, Huntertones some Louis Armstrong and Sinatra as well.

The highs are really clean and extended lot's of air. The image just kinda floats there and they sound very dynamic and fast. You can walk around the balance does not change, very nice I hate head in vice set-ups. Even though the polars look really directional they don't sound that way. Must be that backwave splashing the room.


I have them bi-amped through an M552 24Db L/R at 850/900Hz or so with the notch filters on the Heils powered with a pair of crown PS 200's.

Now I have to finish them, repaint the cabinets and permanently mount the Heil's. Do a step response check to see what the optimum distance is from the front edge of the cabinet. I purchased a pair of mounting kits and they are very nice, have everything you need and the pads tilt the drivers up about 10 degree's or so.

Glad I got them well worth the money talk about bang for your buck! Real easy bi-amp set-up.

Rob:)

[Mr. Widget]

Awesome! Of course those 121A woofers are about 1000% better than anything ESS ever used!
Do you think there would be any benefit to adding a chamfer along the top front edge of the woofer cabinet?


Widget

[SEAWOLF97]

Of course those 121A woofers are about 1000% better than anything ESS ever used!

Widget

I have both a 212 Ultrabass and ESS bookshelves (10 inchers) . Havn't opened the UB to verify that it's a 121a, but have refoamed the ESS driver. It's a high quality alloy casting and I have no disappointments with it.
The UB was never spectacular, tho the veneer was great. So when I read the above statement, my eyes rolled. :rolleyes:

Actually I'd prefer whatever 12 was in the L7's

An LHF member bud of mine (now deceased) relayed the story of how..in the 70's ESS took their AMT 10b speakers and JBL L-100's to college campuses on a tour. They disguised the boxes and did blind sampling. The result was that the larger box, smaller LF ESS's were preferred generally (but not 1000% more)

[SEAWOLF97]

The highs are really clean and extended lot's of air. The image just kinda floats there and they sound very dynamic and fast. You can walk around the balance does not change, very nice I hate head in vice set-ups. Even though the polars look really directional they don't sound that way. Must be that backwave splashing the room.
Rob:)

I have the same experience with my AMT's, but they are sealed on the baffle front, so, at least in my case a backwave doesn't seem to be in the formula.

It may be interesting .... I have 2 pairs of ESS AMT10b's , but they are different. One is ported and the other isn't, tho it has a rear 10 inch PR. I havn't been able to hear any difference between them.

[Earl K]

RobH,

Nice!

Looks quite natural with that 12".

Are you going to create a passive network for this ?

BTW, I've seen a few other references to these large Heils that seem to indicate they're not as sensitive as what you showed in your first post that had them reaching 105db ( something like 5db less than that ).

Did you measure/calibrate at 1M with 2.83 Volts ?

:)

[Mr. Widget]

I have both a 212 Ultrabass and ESS bookshelves (10 inchers) . Havn't opened the UB to verify that it's a 121a, but have refoamed the ESS driver. It's a high quality alloy casting and I have no disappointments with it.
The UB was never spectacular, tho the veneer was great. So when I read the above statement, my eyes rolled. :rolleyes:
I don't disagree with what your ears have been telling you. The 121A was not the right driver for the ultra bass... the Xmax is limited and the design while a great concept was flawed from the beginning.

Unfortunately I was thinking of the 124A/2203 which is a great 12" woofer. The 121A has too much mass and while a good sub for the day, is probably not the last word in a 2-way with the AMT... but it'll be fun for sure and Rob can chime in when he has them dialed in.


Widget

[Robh3606]

I don't disagree with what your ears have been telling you. The 121A was not the right driver for the ultra bass... the Xmax is limited and the design while a great concept was flawed from the beginning.

Unfortunately I was thinking of the 124A/2203 which is a great 12" woofer. The 121A has too much mass and while a good sub for the day, is probably not the last word in a 2-way with the AMT... but it'll be fun for sure and Rob can chime in when he has them dialed in.

Hello Widget

The difference in moving mass between an LE-14-3 and a 121A is 20 grams. Same motor strength as far as I can tell. You take a hit in sensitivity but if it is indeed "slower" I can't hear it. Side by side I don't think so maybe? It's not obvious to me not like comparing at say E-145's which is another animal entirely.

To fix the issue as used in the L212 all you have to do is put them in a vented box. In my current box and tuning I get an F3 @ 27Hz and I can run full power, 100 watts, into them down to about 22hz before I have an issue with over excursion. No problem with the vent speed. Sealed would be another issue entirely as there is not enough excursion for EQ without really limiting the power into them. This way they are fine for music. Limited max SPL though to about 111db for 100watts for the pair which is just fine for stereo.

Also did a full up sweep to 5k looking for break up modes in the phase curve and there are none there nice and smooth. So same cone as a 2203/124A stiffer spider and heavier mass ring.

I am sure the 2203 might be more dynamic as the difference there is 60 grams but you won't get the extended low end in a 2.2 cubic ft box either. It's all about trade offs. No free lunch!

Having fun playing with these things.

Hello Earl

That was not a 2.83 measurement they are less sensitive but they are just fine the way they are. This is staying a bi-amp set-up nice and easy!

Rob:)

[Robh3606]

Does anyone else have their Heils up and running from the sale? I have been enjoying mine not used to dipoles though. My first speaker system using a dipole driver. They sound nice in this room but different from either horns or cones and domes. Depending on how you place them you can get different overall sound stage presentation by aiming the reflections and changing the toe-in.

I finely got a pair of short racks to get the bi-amp set-up off the floor that are good looking and really inexpensive. Currently running 3 PS-200's two bridged in mono and a stereo for the Heils. The source is a Denon universal DVD going HDMI into my Integra and finally balanced interconnects into the crossover. Lot's of fun trying different CD's to see what's up.

Rob:)

[Robh3606]

Just a bump has anyone else who got them in the sale have them up and running?? Seen some posting on DIY not much here. I am really enjoying mine!

Rob:)

[Lee in Montreal]

Are you running JBL 2235 with your Heils? At which frequency are they crossed? TIA.

[SEAWOLF97]

.

[Wallacefl]

Anyone ever copy/replicate the crossover Dennis Murphy for a custom pair of Salk speakers?
I believe it was at about 1600 hz.

[Robh3606]

Just another bump. Got my cabinets refinished holes plugged and old crossovers removed. Anyone else get them up and going?

Rob :)

[jmpsmash]

I was playing with the ESS Heil I got last year from the same sale. Put them with the 2216ND-1 which surprising sound not bad!

Will post pics and measurements this weekend.

[jmpsmash]

That was early last week, but I remember in my measurement the Heil drops off pretty quickly after 10kHz. Your measurements looks much better.

Also I was driving them active crossover and for the Heil I used a 2A3 amp that only have 8 Ohm tap. They are definitely clipping but not sure due to the load being too low impedance or just purely not enough power to drive the Heil.

[Mr. Widget]

That was early last week, but I remember in my measurement the Heil drops off pretty quickly after 10kHz. Your measurements looks much better.

Also I was driving them active crossover and for the Heil I used a 2A3 amp that only have 8 Ohm tap. They are definitely clipping but not sure due to the load being too low impedance or just purely not enough power to drive the Heil.The ESS drivers offer a ribbon like flat impedance curve that is pretty benign.
With the role off and clipping, it sounds like you should try a different amp, if only as a sanity check.


Widget

[Robh3606]

The ESS drivers offer a ribbon like flat impedance curve that is pretty benign.
With the role off and clipping, it sounds like you should try a different amp, if only as a sanity check.

They certainly do but combined with a network you have to watch them as they can end up going low under 4 ohms.

Rob:)

[jmpsmash]

The ESS drivers offer a ribbon like flat impedance curve that is pretty benign.
With the role off and clipping, it sounds like you should try a different amp, if only as a sanity check.


Widget

I will definitely do that.

[jmpsmash]

They certainly do but combined with a network you have to watch them as they can end up going low under 4 ohms.

Rob:)

I am driving them directly from the amp. I haven't found any impedance plots online.

I googled for Heil AMT FR plots and some of them do exhibit roll off but some don't. very strange.

I will try different amps. SS, class d, tube with 4 ohm tap, for a good sampling.

[Robh3606]

I am driving them directly from the amp. I haven't found any impedance plots online.

I googled for Heil AMT FR plots and some of them do exhibit roll off but some don't. very strange.


Hello

I will attach a plot. The light grey is the raw driver the black is with a notch filter and some resistors to bring it up to 8 ohms average. They have had several versions of the diaphragm over time so depending on when the measurements were taken and what diaphragm you get different plots.

Rob:)

[dkalsi]

Anyone ever copy/replicate the crossover Dennis Murphy for a custom pair of Salk speakers?
I believe it was at about 1600 hz.


I just ordered a pair. I will try Dennis's crossover, but before I do, I want to make sure my raw measurements are consistent with his raw measurements.

For those at that are curious, see attachments for Dennis's speaker. The woofer utilized was an 8" Vistaton AL200 (about $135/each at mouser).

[jmpsmash]

Rob you must have an anechoic chamber at home coz I can never get measurement as smooth as your at my room.

Here are mine. They are active DSPed together so I was able to do tweak it some more last night, starting from mostly scratch. I did a better job than last time around. Crossover is LR 24db @ 1200Hz. The result was quite enjoyable and I spent the rest of the evening listening instead of messing around with it.

I don't have the 7kHz notch, but the measurement isn't smooth in general.

85653

The overall is not bad. LR 24db/oct @ 1200Hz.

85652

I like how fast and uniform the Heil decays. But I am more impressed that the 2216ND1 kept up with it all the way down to 100Hz before starting to look messy!

85654

I don't understand how the sum is lower at the crossover point then the individual ones. LR 24db/oct @ 1200Hz. Is it a phase issue?

85655

[dkalsi]

Jmpsmash,

Have you tried gating your measurements? Your measurements seem to include the room response.

You can look at the Impluse Response to see when the first reflection arises, and then gate your measurements just immediately prior to the first reflection.

If the above doesn't make sense, for now try (after you take measurement from say 1 meter) - Tools --> IR Window --> Right Window (ms): 3

See what that does. You will lose low frequency resolution, but you should still be able to see what the AMTs are doing.

[Robh3606]

Hello Jmpsmash

You might want to try the 5K notch. Especially with DSP its a simple low Q notch. That would smooth out the top a bit and with your crossover at 1.2K you could just tweek the level on the Heil up a bit. My raw overall measurement looks pretty similar to yours and the one in the German article.


I don't have the 7kHz notch, but the measurement isn't smooth in general.

Yeah thats weird I thought it was a measurement artifact but no matter where I measured it wouldn't go away.

Rob:)

[Robh3606]

Hello dkalsi


I just ordered a pair. I will try Dennis's crossover, but before I do, I want to make sure my raw measurements are consistent with his raw measurements.

Nice think you are going to like them. How old is that design?? Your measurements may not, you won't know till you power them up with the different versions around. Either way they are easy to work with compared to doing compression driver compensations with horns! Please post you measurements and build!

Rob:)

[jmpsmash]

Jmpsmash,

Have you tried gating your measurements? Your measurements seem to include the room response.

You can look at the Impluse Response to see when the first reflection arises, and then gate your measurements just immediately prior to the first reflection.

If the above doesn't make sense, for now try (after you take measurement from say 1 meter) - Tools --> IR Window --> Right Window (ms): 3

See what that does. You will lose low frequency resolution, but you should still be able to see what the AMTs are doing.

Yes I did and it made little difference. Some wiggles here and there but overall shape of the response remains mostly the same.

[jmpsmash]

Hello Jmpsmash

You might want to try the 5K notch. Especially with DSP its a simple low Q notch. That would smooth out the top a bit and with your crossover at 1.2K you could just tweek the level on the Heil up a bit. My raw overall measurement looks pretty similar to yours and the one in the German article.



Yeah thats weird I thought it was a measurement artifact but no matter where I measured it wouldn't go away.

Rob:)

Let me try that. I will also try to play around with the placement. Right now the Heil is sitting on the (not connected) JBL 2397. I will try to remove that heavy thing and measure again. That should knock off a few bumps on the FR. I also wonder if putting the Heil on a stand, a few inch tall to minimize interaction with the top of the cabinet, will help.

[dkalsi]

Hello dkalsi

Nice think you are going to like them. How old is that design?? Your measurements may not, you won't know till you power them up with the different versions around. Either way they are easy to work with compared to doing compression driver compensations with horns! Please post you measurements and build!

Rob:)


Rob - I believe that design was from early 2011.

I really doubt my driver measurements will match Dennis's.

I must say you got your hands on a pretty decent pair. While there may be response variances year to year, I sure hope there is (little-to) no variance between the two pieces I receive.

I'm getting anxious waiting for them to ship. Apparently, while the keep all parts on hands, they don't assemble the units and QC test until orders/payments are received. I placed my order this part Saturday --> they are not expected to ship out until tomorrow.

[Earl K]

Let me try that. I will also try to play around with the placement. Right now the Heil is sitting on the (not connected) JBL 2397. I will try to remove that heavy thing and measure again. That should knock off a few bumps on the FR. I also wonder if putting the Heil on a stand, a few inch tall to minimize interaction with the top of the cabinet, will help.


Measure your Heil on axis from a foot away using a test mic with it's calibration file loaded.

All those caveats/conditions will change the response that you are currently showing.

:)

[toddalin]

I just ordered a pair. I will try Dennis's crossover, but before I do, I want to make sure my raw measurements are consistent with his raw measurements.

For those at that are curious, see attachments for Dennis's speaker. The woofer utilized was an 8" Vistaton AL200 (about $135/each at mouser).


Not what mine looks like.:dont-know:

I use mine as a tweeter. This is the crossover, thought there have been changes to the mid.

http://www.audioheritage.org/photopost/data//500/medium/ScreenHunter_219_Dec_06_15_31.jpg



This is the spectrum in the room at 1 meter on axis without my wedgie.
http://www.audioheritage.org/photopost/data//500/medium/DSC_000215.JPG


And here it is with my wedgie. Note that it is 2.5 dB between sets of horzontal lines. (And they said I was mad! :p )

http://www.audioheritage.org/photopost/data//500/medium/DSC_000116.JPG

[jmpsmash]

Measure your Heil on axis from a foot away using a test mic with it's calibration file loaded.

All those caveats/conditions will change the response that you are currently showing.

:)

True. But a bit academic as I am not wearing them as headphones. :)

[jmpsmash]

This Heil AMT has been quite enjoyable.

The character is different than a compression driver horn. On the plus side, it is quite dynamic and fast (though not as fast as compression horn). The really good part is that being a dipole it has great sense of space and airiness. It is also a bit less harsh, so less listening fatique even at higher volume. With horn, even with the 2397 which is supposed to be less "horn" like, I still cannot listen for hours without rest.

However, as mention, it is not as dynamic, esp microdynamic. Less detail. It also image slightly worse. instrument position is not as clear.

[Earl K]

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=85653&d=1579105329

Based on extrapolating the following info ( of three different "on & off" axis measurements ) I would guess that your measurement axis was " down/up & away ". ( Maybe 30deg-H x 15deg-V ) ??

85662

:)

[Earl K]

I just ordered a pair. I will try Dennis's crossover, but before I do, I want to make sure my raw measurements are consistent with his raw measurements.

For those at that are curious, see attachments for Dennis's speaker. The woofer utilized was an 8" Vistaton AL200 (about $135/each at mouser).

Hi Dhar,

I have to imagine that those measurements from Dennis were from an earlier generation of large Heils.

Here's a comparison of Rob's measurements with those of Hobby HiFi ( I slightly shifted the FR of the Hobby HiFi trace to lineup the 5K bump ) to compare the general shape of the curve.

85663

Above 3K, I would say one would have a real challenge hearing any difference.

:)

[dkalsi]

Hi Dhar,

I have to imagine that those measurements from Dennis were from an earlier generation of large Heils.

Here's a comparison of Rob's measurements with those of Hobby HiFi ( I slightly shifted the FR of the Hobby HiFi trace to lineup the 5K bump ) to compare the general shape of the curve.

85663

Above 3K, I would say one would have a real challenge hearing any difference.

:)


Thanks, Earl!

That is pretty impressive range (500hz - 20Khz). May not be untrue that it can be crossed as low as 800hz. Mine will not be shipped now until tomorrow; thus, I don't expect to have mine until the end of next week (from CA to MD). As soon as mine arrive, I will take measurement (+/-90 degrees horizontal, and +/-30 degrees vertical).

[Wallacefl]

I have used the Heil in the past and disliked the simblence which may have been the 5-7 k peak. Though way more complicated I wonder how it would be as strictly a midrange ie: VOLENT speaker Paragon VL-4. Might be good from say 1.2-5k and then use a ribbon tweeter beyond.

[Robh3606]

I have used the Heil in the past and disliked the simblence which may have been the 5-7 k peak.

I am using a pair now. Don't have a sibilance issue with them. I have am using a notch filter to tame the peak.

Rob:)

[jmpsmash]

The other issue is that the Heli only go down to ~1kHz. What to put in the very important ~200-1kHz range that will match its speed?

[jmpsmash]

Last night I cleaned up the setup. Removed all the clutter, and then putting the Heil at the front edge of the 15" cabinet, overhanging just slightly, and then raised up by 1" to give the V shaped throat a bit of space to breath instead of hitting the top edge of the cabinet. And then time aligned electronically.

Results is more defined imaging and clarity.

I will post pics and measurements later today.

[toddalin]

The other issue is that the Heli only go down to ~1kHz. What to put in the very important ~200-1kHz range that will match its speed?

2251J

http://www.audioheritage.org/photopost/data//500/medium/DSC_000413.JPG
http://www.audioheritage.org/photopost/data//500/medium/DSC_00069.JPGhttp://www.audioheritage.org/photopost/data//500/medium/DSC_00058.JPG

[toddalin]

Last night I cleaned up the setup. Removed all the clutter, and then putting the Heil at the front edge of the 15" cabinet, overhanging just slightly, and then raised up by 1" to give the V shaped throat a bit of space to breath instead of hitting the top edge of the cabinet. And then time aligned electronically.

Results is more defined imaging and clarity.

I will post pics and measurements later today.


I just slide mine back and forth and watch the results on the RTA looking for the smoothest curve.

[jmpsmash]

2251J


Nice! Did you build that enclosure?

I have a practically brand new 2123H that have been sitting around. Time to bring out the saw table...

I am still not sure if a traditional driver will be fast enough. Though probably better than relying on a heavy 15" driver. For faster speed, may have to go with a midbass horn (really big), or a planar driver. I just got myself 4x BG Neo10. Should have it next week. It can cover ~200Hz upwards. Still won't have the dynamics of horns but the ears will tell.

[jmpsmash]

to follow up. here is a measurement after clearing some junk around the Heil and also raised it 1 inch (dark green), and 2 inch (purple) from the top of the cabinet, measure from ~1m.

Yellow is near field, 3 inches away. Light green is 1 inch away.

[toddalin]

Nice! Did you build that enclosure?

I have a practically brand new 2123H that have been sitting around. Time to bring out the saw table...

I am still not sure if a traditional driver will be fast enough. Though probably better than relying on a heavy 15" driver. For faster speed, may have to go with a midbass horn (really big), or a planar driver. I just got myself 4x BG Neo10. Should have it next week. It can cover ~200Hz upwards. Still won't have the dynamics of horns but the ears will tell.

Yes, I built them and they are rear ported. The 2251J was actually designed to be used in a midbass horn enclosure. A 2241H is crossed over at 225Hz.

Lately I've taken to running the system as a 2.5 way letting the 2251J roll off naturally at its bottom end. Taking the high pass (32.5 mfd) cap away does a nice job of flattening its frequency response, and the cap was only reducing the volume by ~1 dB down at 40 Hz, so really wasn't providing critical "protection." Anyway, this is used in a home environment and can blow my ears out before doing any damage to the driver, rated at 400 watts.

The 2251J is a very fast speaker because the cone is very light with an accordion edge and it uses the differential drive system and has no measureable inductance of its own. When you look at the Heil plots, I cross it over around 4KHz so that the 5kHz peak is reduced into the area so that blends with the 2251J.

Similarly, the 2251J gets rough up in this area, and crossing it at about 2kHz flattens that rise between 2-4K, and the anomolities above that drop like a stone letting it blend with the Heil.

Internet plot of 2251J:

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=14574&stc=1&d=1144095010

[toddalin]

Most current version of the crossovers. The 0.9/30 ohm control the high cutoff frequency of the 2251J while the 6.8 "squares" off the top of the band. The 0.065/2.37 control the interface to the Heil. A smaller value resistor will result in a peek ~5KHz whereas omission will result in a dip between the drivers. Don't forget the Heil's "wedgie."

http://www.audioheritage.org/photopost/data//500/medium/ScreenHunter_228_Jan_19_17_16.jpg

[jmpsmash]

I did some sim before and had planned to make a 1/2 cu ft sealed box for the 2123. I think seal box will give a faster response. Never gotten around to building it though. Too much stuff to play with at the moment. :D

[toddalin]

I did some sim before and had planned to make a 1/2 cu ft sealed box for the 2123. I think seal box will give a faster response. Never gotten around to building it though. Too much stuff to play with at the moment. :D

When I close off the port, the 2251J just doesn't sound as good nor is as flat.

[dkalsi]

Per UPS tracking, the Heils have arrived. I plan on taking measurements later today/tomorrow.

Wanted to know if people are using a protection cap (e.g. 50uF or 80uF) in series for measurement purposes?

From what I've read, the AMT technology is nothing like ribbon technology, which does require a protection cap prior to measurements, and that the AMTs should have no trouble being measured full-range (assuming its at relatively low levels).

Thoughts?

[Robh3606]

Wanted to know if people are using a protection cap (e.g. 50uF or 80uF) in series for measurement purposes?

You could, I didn't. You could also limit a sine sweep or just use Impulse. Just do whatever you are comfortable with.

Rob:)

[dkalsi]

You could, I didn't. You could also limit a sine sweep or just use Impulse. Just do whatever you are comfortable with.

Rob:)

I don't think I will use a protection cap. They can be safely played down to 800hz with a second-order crossover <- that makes them pretty robust in my book. Plus given their efficiency, I plan on feeding them minimal power for messurement purposes.

I just really hope they measure the same.

[jmpsmash]

I scan them without protection cap from 200Hz upwards with a 4W amp. No problem. :applaud:

[dkalsi]

Hi All,

Can someone please post raw measurements of the AMT drivers? Both Left and Right - just the AMTs.

I just measured my pair and there is about 3-4 db in overall variance, with one measuring an almost flat 4.2 impedance, and another one measuring 3.3 impedance.

[toddalin]

Both of mine have a dc resistance of 2.9 ohms, which is why I run a 5 ohm resistor in series and use an 8 ohm L-pad.

[Ian Mackenzie]

Hi All,

Can someone please post raw measurements of the AMT drivers? Both Left and Right - just the AMTs.

I just measured my pair and there is about 3-4 db in overall variance, with one measuring an almost flat 4.2 impedance, and another one measuring 3.3 impedance.

I made a comment in other diy thread about QC. I am told from a very reliable source when the Heil was introduced by ESS that they were difficult to manufacture with close consistency.

So if yours actually measure different that’s how it is.

It would not be difficult to adjust the output in the crossover so that they match. The FR possibility won’t match.

[dkalsi]

I made a comment in other diy thread about QC. I am told from a very reliable source when the Heil was introduced by ESS that they were difficult to manufacture with close consistency.

So if yours actually measure different that’s how it is.

It would not be difficult to adjust the output in the crossover so that they match. The FR possibility won’t match.


You are right. I'm in the process of building a bass cabinet to go along with these. I'll see how difficult it would be to get them to match (moreorless) via the crossover.

[Ian Mackenzie]

Btw those schematics are only accurate for the original woofers involved. You don’t know the frequency response character so the woofer schematic is only ball Park. As I recall ESS only went for 8, 10 and 12 inch ? drivers.

So what really works is a matter of experimentation per usual.

As they say nothing is plug and play and in real audio everything matters.

[badman]

I made a comment in other diy thread about QC. I am told from a very reliable source when the Heil was introduced by ESS that they were difficult to manufacture with close consistency.

So if yours actually measure different that’s how it is.

It would not be difficult to adjust the output in the crossover so that they match. The FR possibility won’t match.


I visited the current ESS factory some years back. The diaphragms are difficult to make and are actually folded manually, but the current generation of diaphragms seems to have pretty good QC. Older diaphragms are challenging- there have been a number of variants over the years, including polyethylene and mylar variants. Currently it's mylar, but the polyethylene would likely have higher internal membrane damping (not sure it matters for an AMT). My PE phragms are badly deformed, PE is soft and heat sensitive.

Basically, you have to measure and validate.

[jmpsmash]

I have a pair of current production Heil. Let me make some comparative measurement this weekend.

[SEAWOLF97]

Older diaphragms are challenging- there have been a number of variants over the years, including polyethylene and mylar variants. Currently it's mylar, but the polyethylene would likely have higher internal membrane damping (not sure it matters for an AMT). My PE phragms are badly deformed, PE is soft and heat sensitive. .

good info ... is there a way to tell what your AMT is ? Mine seem very smooth sounding and as I presume they are supposed to be.

[toddalin]

Mine came from the AMT 1D line. They actually look a bit different than the earlier/later versions.

[dkalsi]

I have a pair of current production Heil. Let me make some comparative measurement this weekend.


Thank You! - I look forward do it.

[dkalsi]

Took few measurements this evening:

(1) Sample 1 vs Sample 2 - Frequency Response
(2) Sample 1 - Distortion (2.83v at terminal - mic 20in from driver)
(2) Sample 2 - Distortion (2.83v at terminal - mic 20in from driver)

Distortion seems awfully high and maybe that's why I haven't been super impressed (just yet).

Its almost as if some assembly is resonating inside (not just the diaphragm - but the whole diaphragm assembly inside is resonating).

[toddalin]

Took few measurements this evening:

(1) Sample 1 vs Sample 2 - Frequency Response
(2) Sample 1 - Distortion (2.83v at terminal - mic 20in from driver)
(2) Sample 2 - Distortion (2.83v at terminal - mic 20in from driver)

Distortion seems awfully high and maybe that's why I haven't been super impressed (just yet).

Its almost as if some assembly is resonating inside (not just the diaphragm - but the whole diaphragm assembly inside is resonating).

Your plots confirm what I see on my RTA. I don't know why these people keep showing plots with a decrease in volume after the 5KHz hump. My plots, even without the crossover, show a continuing rise above this point which is why I devised the wedgie. I don't know why you don't show the drop after ~14K, (my soft room?) but if you are using the Heils as pictured above by Seawolf, they are not the "Great Heils" as I use.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=85728&stc=1&d=1579912628

http://www.audioheritage.org/photopost/data//500/medium/DSC_000215.JPG

With the wedgie:
http://www.audioheritage.org/photopost/data//500/medium/DSC_000116.JPG

[Earl K]

Hi "D"

This pic is ( IMHO ) un-necessarily cluttered with distortion products that are usually ignored.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=85730&stc=1&d=1579912667

I'd suggest displaying only the 2nd, 3rd & 5th harmonics as seen in the following pic ( clipped from the previously mentioned german pdf article highlighting these AMT's ).

85731

I also believe your measured distortion numbers would be a lot more comparable ( to what's seen immediately above ) if you measured at 90db ( at 1 meter distance ) like the magazine did.

( Just saying > measuring at 1/2 a meter at 2.83 volts will naturally jack-up the distortion readings ! )

:)

[toddalin]

What are people doing about the rear wave and what was done in other simulations? Is the elevated distortion at lower frequency possibly due to rear wave cancellation/destruction?

Would a set of "wings" help?

http://www.enjoythemusic.com/diy/1211/heil_amt1_horn.htm

[jmpsmash]

Dispersion measurement. Not bad. By the time it got to 50 degrees, the microphone can no longer "see" the diaphragm directly.

85733

[jmpsmash]

Distortion. Looks quite good from 900Hz and probably can go down to 800Hz.
85734

[jmpsmash]

Comparison of my 2 Heil AMT's. They are produced on the same day, consecutive serial numbers.

Note the scale. They are within 2dB of each other without large deviation in overall shape.

The distortion from the green one is higher, around 2-3dB. REW doesn't seem to have a way to overlay the distortion on the same graph.


85735

[jmpsmash]

Phase measurements, comparing the 2 units.

Here is the weird one. And I have double checked the wiring and double checked the measurement. If I wire the positive to blue, and negative to brown, the same way on both drivers, they are 180 out of phase!

After I flip the pos/neg on one of them, the phase is completely in sync again. WTF?

85736

[toddalin]

Phase measurements, comparing the 2 units.

Here is the weird one. And I have double checked the wiring and double checked the measurement. If I wire the positive to blue, and negative to brown, the same way on both drivers, they are 180 out of phase!

After I flip the pos/neg on one of them, the phase is completely in sync again. WTF?

85736

Got a compass??? ;)

[jmpsmash]

Got a compass??? ;)

Are you saying, since it is a symmetrical dipole, just point it backwards? :applaud:

[jmpsmash]

Impulse response comparison. The wires are flipped, confirmed85737!

[Robh3606]

That's odd! Well at least you know. Here is a distortion measurement I did a while back. It's overall THD Sine Sweep.

Rob:)

[Earl K]

That's odd! Well at least you know. Here is a distortion measurement I did a while back. It's overall THD Sine Sweep.

Rob:)


Really, there's not much odd here about any of the preceding distortion measurements.

Your measurement ( at 110db ) indicates over 3% which is in line with the other measurements ( yours is higher since it's done at a louder level ) .

Distortion Conversions (http://www.sengpielaudio.com/calculator-thd.htm)

:)

[jmpsmash]

Really, there's not much odd here about any of the preceding distortion measurements.

Your measurement ( at 110db ) indicates over 3% which is in line with the other measurements ( yours is higher since it's done at a louder level ) .

Distortion Conversions (http://www.sengpielaudio.com/calculator-thd.htm)

:)

110dB is crazy high. I am measuring at ~80-90dB. My family won't talk to me anymore and that's not just because I am wearing earplugs!

[Robh3606]

That is not a 1 meter measurement but yes it was loud as hell and worst case. I would never listen to them at anywhere near that at average levels. I am about an 85db - 90db listener depending on the source material.

Rob :)

[dkalsi]

Hi "D"

I'd suggest displaying only the 2nd, 3rd & 5th harmonics as seen in the following pic ( clipped from the previously mentioned german pdf article highlighting these AMT's ).

85731

I also believe your measured distortion numbers would be a lot more comparable ( to what's seen immediately above ) if you measured at 90db ( at 1 meter distance ) like the magazine did.

( Just saying > measuring at 1/2 a meter at 2.83 volts will naturally jack-up the distortion readings ! )

:)

Duly noted - I'll take additional measurements at 90db and will show 2nd, 3rd, and 5th.

[dkalsi]

110dB is crazy high. I am measuring at ~80-90dB. My family won't talk to me anymore and that's not just because I am wearing earplugs!

Is the 80-90db at 1m?

[jmpsmash]

Is the 80-90db at 1m?

2 feet.

[jmpsmash]

Impulse response comparison. The wires are flipped, confirmed85737!

wired them "correctly" just now and did some listening. so much more focused than before.

Overall, the sound of the Heil is a bit... not sure how to describe it, maybe "grainy"? Not clean and smooth like a metal dome tweeter, but has a certain texture to it.

[SEAWOLF97]

some years back I picked up a pair of FORTUNA towers in crappy shape. That was an ESS bargain label.

Up on top were these ..worked great.

sold on eBay to a buyer in HK. Fell off a pallet in their P.O. and were run over
by a forklift.

sorry to see them end up that way ..:eek:

[toddalin]

Rob,

I came up with a new concept for the Heils that you may want to try. I've found that it increases the volume by ~0.5 (measured on a Quest 2900 Type 2 meter) and adds clarity and articulation. I attribute this to a reduction in sidewall and room interaction, and even saw some reduction of suck-out, but would love to see it swept to see where the differences lie.

Oh, the modification cost <$3.

Go to Michaels Crafts and get one of these triangular Eva "dowels" in 30MM. They are even on sale from the web price and mine were in the bargin bin for $1.47 each so I got two. You can also get them as half-rounds which would have a bit of a different effect on edge diffraction. Simple and cheap enough to try both. They call it foam, but it's really a very soft and pliable rubber-type product (Ethylene-vinyl acetate). I tried a sample and found the material to be totally compatible with Rustolium Ultra-coat satin black primer, even when saturated.
https://imgs.michaels.com/MAM/assets/1/5E3C12034D34434F8A9BAAFDDF0F8E1B/img/8667F8D5AFF2441F964E6EA605BC4DD7/10624925_1.jpg?fit=inside|540:540

https://www.michaels.com/24in-eva-foam-triangle-foam-dowel-by-artminds/10624921.html?productsource=HPRV#

https://www.michaels.com/24in-eva-foam-triangle-foam-dowel-by-artminds/M20001752.html?dwvar_M20001752_size=15%20mm&dwvar_M20001752_color=White
https://www.michaels.com/24in-eva-foam-triangle-foam-dowel-by-artminds/10624921.html?productsource=HPRV


You can also get them online, but pay shipping and they usually cost more. You can also get them on-line in black, for lots more $$$ (not at Michaels though). I painted mine with Rustolium Satin Black Primer/Paint and there is no prolem with compatability. They came out beautiful and are drying.

Because of the rubber gaskets on the bottom of the Heils, mine are 6-1/8" tall, but 6" will work for just the Heils and with a 24" long piece, you could do all four..., BUT,

It cuts very easily with a razor blade or very sharp knife. But I found it thicker than a single-edged razor blade could do in one pass, and working around the triangle, you don't get a perfect cut.

Easy enough. I bought two and cut them to 6-1/4" and used a disk sander to trim them to the exact length. Yes, you can easily sand this "rubber" on the wheel/belt to a perfectly smooth edge for the top and bottom.

And what does this gain us??? I measured the outter diagnol "surface of the Heil at ~40 MM. The wedges add an additional 30 MM or an additional 75% of the length (a bit less if considering the actual distance to the diaphragm). If we were to consider this as a horn, it could push the loading down well over half an octave in the affected range.

Note how the 30MM span perfectly aligns with the "flats" and carries the angle to within 1 degree. It looks like something ESS should have offered to complete the look, if nothing else, though it does add 1" of protrusion. (Ethyl Merman also had protrusions.)

http://www.audioheritage.org/photopost/data//500/medium/DSC_000424.JPGhttp://www.audioheritage.org/photopost/data//500/medium/DSC_000522.JPG

[Robh3606]

Hello Toddalin

I missed this. OK why not have to wait till I get them up and running again. They have been temporally "retired" I didn't realize that they used a 60 degree angle on the "wings". Good to know!

Thanks Rob:)

[toddalin]

I had initially figured 60 degrees based on the acoustic wedge foam. But that actually has 10 wedges per 30 centimeters, so is a bit off (wider than) of 60 degrees

Actually, turns out that when you fit the wedge piece, the angle on the Heil is a bit wider than 60 degrees, and the triangle's angle the sound in (rather than out) a few degrees focusing it in the sweet spot. As I noted, it added ~0.5 dB. But, I think that in doing so, it also produces a sound that more approximates the JBL horns' presence (without the problems) and adds even more impact than was there. I use the L300s as reference and those features (voicing) that I like I try to emulate, as well as vice versa. I think this provides some of the positive qualities.

Certainly gives them a "finished" look.

When I went back to Michaels, they had further dropped the price to $1 each so I bought another as well as a couple half rounds. I figured that I could use some double sided tape and tape the cut pieces to a flat bar, then "lay it back" and run it though the mill to get the exact angle keeping the full 30MM of length.

I may also take the half round and lay back the inner edge to that of the horn and apply these removing the front "flats" and rounding out the curve. This may help dispersion (not a concern) and imaging (always a concern).

Isn't it worth ~$1-2 just to try?

http://www.audioheritage.org/photopost/data//500/medium/DSC_00118.JPG

[JeffW]

Lt. Hurwitz has never looked so good! :D