My Great Great Heil DIY Speakers

Markus111

Big Horns & Many Tubes
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I picked up a pair of the great Heil AMT tweeters a while ago, and have been working on building a set of DIYs around these amazing tweeters. I started out by measuring the frequency response and impedance, and then trying to figure out how best to mate a woofer to these. Since they are a pleated ribbon construction, they would require a pretty fast woofer to keep up, and probably no more than 8 inches in diameter. The impedance looks pretty good, and the frequency response is simply amazing.

heilonaxis.jpg


heilimpedance.jpg



Initially, it looks like I would want to cross over no lower than 1000 Hz. I looked at quite a few woofers, and there were many that would fit the bill. But I couldn't find any that would give good sensitivity and frequency response at a price that I wanted to pay. I decided to go with 2 8 inch woofers instead, and this opened up a lot more possibilies. I finally settled on the Dayton RS225 woofers wired in parallel. This would give me about 90db sensitivity, and the 4 ohm load would match the Heil tweeters. These woofers look spectaculare up to about 1400 Hz, and then they exhibit some pretty severe breakup modes due to the aluminum cones. Still, they looked like a good match for the tweeters.

rs225freq.jpg



One of the design criteria for the speakers is they will have to be comfortable in the corners of my listening room. Because of this, I decided to go with a fairly large cabinet, and tune it lower than normal. This will roll off the bass from about 200 Hz down, which should help compensate for the 8 Pi room gain. I also wanted to avoid having to put any baffle compensation in the crossover. Since the crossover point at 1000 Hz, I made the baffles 12 inches wide. This will make the speakers effectively monopole from 1000 Hz down. Hopefully this will simplify my crossover a bit.

The cabinets are coming along nicely. I decided to go with baltic birch for the sides, MDf for the top, bottom, and braces, and 1 inch particle board for the baffles. Everything is rabbeted and glued together. The fronts get walnut and zebrawood veneer, and the trim pieces are mahogany. I'm using water based poly and dye to finish them. So far, I like what I'm seeing.


heil-diy-1.jpg

heil-diy-2.jpg

heil-diy-3.jpg


I plan to use 4th order Linkowicz-Riley crossovers for both the woofers and tweeters. From using simulations using my measured data, it looks like this will provide a good match, as well as taming the breakup modes in the woofers. I hope to get around to building the crossovers in the next week. Thanks to Kegger and PakProtector for the finals bits I need to build them.

heilxoverresponse.jpg

rs225freqxover.jpg




Stay tuned for further updates!

Mark
 
In the old ESS line, there was one model that used a midrange, the AMT-3. Many folks agree that the AMT-3 was by far the best-sounding ESS model. I got two pairs off eBay a while back (one pair ok and one damaged), and I've been looking for someone to assemble them into a more modern whole. The best advice I've gotten came from AK's own Ron-C:

"...You can use the Eminence LA6-MB 6 1/2 " mid in your AMT-3s. I put these in mine and they are awesome. You will have to set the rear control to bright so the Heil matches up. Put a .1 poly cap across the +, -, connections behind the heil for added smoothness.
You can buy the mids at Parts Express and these will move you up to about 95 dB per watt. These mids blend right in and yes I measured them, so smooth and detailed. Oddly your bass will improve with this change in mids.
I have all the parts for new high efficiency crossovers but have not got around to it yet.
I am also going to the DeltaLite 2510 Eminence on the bottom but have not tested them yet. I have a set of the 2510s in my AMT-1 towers and they are the best I have used so far but these will never sound as good as the AMT-3s. I have tried lots of 10" drivers in these. Eminence drivers are just about state of the art without getting into the tweaky low eff. drivers which are always wrong for the Heil."

Wild guess, your project will sound good as-is, but it looks like you've got room in those cabinets for another driver, so even though your woofers will go high enough to meet the lower end of the Heil, you might consider a midrange. Other than that thought, your project looks fantastic.

Good luck, and please keep posting on your progress!
 
Thanks for the reply! I considered a three way design, but I would like to emphasize the effect of the dipole tweeter by running it as low as I could. Plus, three way crossovers can get pretty complicated. Hopefully this works out well!

Mark
 
Markus111 said:
Thanks for the reply! I considered a three way design, but I would like to emphasize the effect of the dipole tweeter by running it as low as I could. Plus, three way crossovers can get pretty complicated. Hopefully this works out well!

Well, the great news is that you can finish them the way you've started, and afterwards, you can always experiment with the 3-way just by buying a pair of drivers.

Again, keep up the posts!
 
Interesting Mark, looking forward to seeing how these turn out.

What software and hardware are you using for measurements?
 
Billfort said:
Interesting Mark, looking forward to seeing how these turn out.

What software and hardware are you using for measurements?

For the tweeter, I used Speaker Workshop by Audua. If you're familiar with the site, I built the Wallin Jig and I run that into a Soundblaster Audigy. For frequency measurement, I use the Berhinger ECM calibrated mic fed into an ART preamp with phantom power. I've been using this setup for a while, and it produces some very good results. My only beef is with the Soundblaster software that comes with the Audigy card. There is always a feedback between the output and input of the sound card. This doesn't effect the impedance measurement, but it makes the frequency measurement a real pain. You can get it set up to measure properly, but it takes a lot tweaking in the windows settings. I may eventually get a different soundcard that has better software controls.

I haven't measured the woofers yet. I am using the measured responses provided by Dayton, and importing them into Bassbox pro. As soon as I get the woofers mounted in the cabs, I'll use my Speaker Workshop setup to do some extensive measuring and tuning. What I need to find is a conversion program that can convert between all of the major speaker measurement and analysis formats. Most manufacturers these days provide measurments made with LEAP, but I can't import these files without doing a lot of manual manipulation to the file.

All in all, though my setup works very well. When I take the time to set everything up properly, I have very good confidence in my results. I've used the speaker workshop setup to design several sets of speakers so far, and I've been pleased with the results. I'm hoping for another success!

Mark
 
I'm going to have to bug you on setting up this Speaker Workshop stuff Mark as it seems I'm going down the same path as you. I've built the Walling jig, have the software loaded, an Audigy2 ZS soundcard for my laptop, Behringer ECM8000 test mic and MicroMIX mic pre-amp with phantom.

I got rolling with set-up and started to wade through a few of the on-line instruction manuals for the software and kind of got lost with my eyes glazing over when I was going through the calibration and software configuration sections. I'll dive back in when I get a little time as I have a bunch of projects this winter where I want to use this but it would be great to talk to somebody like yourself who has mastered this stuff.

Sorry for dragging this off topic but seeing a project like your Heil build really peaked my interest for Speakerworkshop again - the way you are measuring and designing here is pretty inspirational.
 
Markus111 said:
Initially, it looks like I would want to cross over no lower than 1000 Hz. I looked at quite a few woofers, and there were many that would fit the bill. But I couldn't find any that would give good sensitivity and frequency response at a price that I wanted to pay. I decided to go with 2 8 inch woofers instead, and this opened up a lot more possibilities. I finally settled on the Dayton RS225 woofers wired in parallel. This would give me about 90db sensitivity, and the 4 ohm load would match the Heil tweeters. These woofers look spectacular up to about 1400 Hz, and then they exhibit some pretty severe breakup modes due to the aluminum cones. Still, they looked like a good match for the tweeters.
I'm not going to begin to try and convince someone I'm a speaker expert. Far from it. But, there happens to be one speaker I know a little bit about, and that is the 'big' or 'Great' Heil AMT. Been using one for over 20 years. Yes, they can be crossed over as low as 1000Hz, but I do not particularly care for the nasal-sounding midrage you get from them at the lower end of its response range. In a two-way setup, the best route is to use a 6 1/2" or 8" woofer (two per cab, if you like) that has decent response out to 3K or so, and cross over to the Heil at 2.2K to 2.6K.

There are a lot of good woofers out there that can do the job well out to 3K and beyond.

My $0.02. Best of luck!
 
my Heils crossover is at 2k with 12 inch woofers and passive radiators on the back, i am thinking of putting new woofers in them to use them with my guitar synthesizer and will be watching your progress here.Also if you would like to talk to Bob Heil you can find his website by searching his call K9EID or you can find him in the phone book for Fairview Heights,IL under his business Heil Sound.

keep us informed
Randy KB9KXH
 
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Many have said the Heil doesn't sound right when x'sed lower then 2K, I've said
it before and will say it again, I really really like the sound of my AMT-6's which
x much less then 2K, I see nor hear anything that would make me think there is
an issue with this setup.:D

Now mine does use 4 heils per speaker and maybe using that many is the reason
why I feel my sounds quite right, maybe more area or just more drivers helps.

I may still experiment in the future with trying 2 mids in place of 2 of the heils.:scratch2:

By the way Mark I gotta get by your place and hear those.:music:
 
I had a pair of 1A's in the early 80's while in college at Ohio State. My roomies melted the heils several times. I was never around when this happened so I don't know what they were doing. At the time I was told that the crossover point was to low. I eventually sold them and replaced them with JBL 4311's. I just recently found a set of 1a's at the thrift (see my post about knuckleheads with sharpies) which I've refoamed. I'm still getting used to them but I love them all over again. No roomies this time either. Looking forward to see the final results as I'd like to put the heils in a different cabinet and biamp them.
 
Kegger said:
Many have said the Heil doesn't sound right when x'sed lower then 2K, I've said it before and will say it again, I really really like the sound of my AMT-6's which x much less then 2K... mine does use 4 heils per speaker and maybe using that many is the reason why I feel my sounds quite right, maybe more area or just more drivers helps.

Your theory is correct, methinks. Take, as an example a pair of Infinity IRS Vs compared to IRS Betas, which were both made at the same time. The Vs use a line array of mid/tweets (called EMIMs). The Betas use one EMIM, and two huge mid/bass drivers called L-EMIMs. It takes a lot of the little drivers (20 or so?) to make up for the larger mid/bass units and sound correct.

Interestingly, there is a camp that thinks Betas sound better than Vs because the Vs always seem to be missing something in the 'warmth' range that the Betas have in plenty. In his own system, Harry Pearson solved this problem by attaching a pair of Magnepan mid-bass panels to the Vs, the results of which were thought by almost everyone who heard them to be the finest speakers made at the time. They remained HPs reference for a long time, IIRC.

Today, Von Schweikert's $85,000 VR-10 Mk IIs have an interesting explanation of his driver choices in which he states that most of the large 'statement' systems fail in the warmth range, and he deliberately put in four mid/bass drivers to prevent that.

The mid/bass unit in the AMT-3s addresses exactly this problem. But as said before, there's no reason not to proceed as planned, and experiment with a mid/bass unit later.
 
Negotiableterms said:
But as said before, there's no reason not to proceed as planned, and experiment with a mid/bass unit later.

Yeah - I'm kind of committed at this point. Thanks Kegger and Indm for your comments as well. I've read quite a few opinions of these tweeters now, and as with any audio component there are lots of contradictory comments. That's the nature of the beast, I guess. The good thing is that I have lots of room to experiment, which I kind of kept in mind from the beginning. I will start with two 8 inch woofers and the Heil as planned. I've read several posts now where people (including Paul Klipsch!) have put limited baffles behind the Heil to increase the warmth of the midrange. That will be my second experiment. Finally, I can add a midrange driver if I really find the sound lacking. This will probably be an evolution over quite a bit of time, as I like to leave the system alone and just listen for a few months.

As far as progress goes, the cabinets are almost complete. I hope to get some more pictures up tomorrow. Boy Howdy, are these things getting heavy! I decided to make the cabinets in two pieces, with the Heils and crossovers in removable tops, and the woofers in the bottom. This way, I can at least move them around. I plan to take these to AudioKarma Fest in March, as long as they don't suck :D Stay tuned!

Mark
 
Markus111 said:
Yeah - I'm kind of committed at this point.

Actually, the more I think about it, the more your approach makes sense. The first Heil product was the AMT-1, which was a 2-way like yours. It went through several iterations before the more complex AMT-3 came out. It makes a lot of sense to "perfect" the 2-way before tinkering with the 3-way, because you'll learn a lot in the process.

Markus111 said:
I plan to take these to AudioKarma Fest in March, as long as they don't suck.

They won't suck, that's almost guaranteed, and I'm really looking forward to hearing them!
 
Well, I've made some progress on the cabinets. I ended up taking a few twists and turns in the road here, and I'll explain as I go along. I originally planned to bolt the Heil right to the top of the cabinet, and then construct a top which would cover the Heil and provide a solid top. However, once I got the woofer cabs put together and loaded, I decided to go back to the drawing board. The woofer cabs alone were 60 pounds, and then adding all of the stuff on top would take them to over 100 pounds! Since I would like to be able to move these some day, I decided to go with two completely separate cabinets that bolt together. Here is a picture of the tops constructed and bolted on to the woofer cabinet.

heil-with-top.jpg


I also indicated earlier that these would be stuck into the corners of my room, so I tuned them low to roll them off. This of course implies that these speakers will ALWAYS be used in corners. Since I may someday move or put these in a different room, I decided to go with a port tuning that I could change if I wanted to. I ended up building the ports on removable panels that screw into the back of the speakers. This will allow me to just unscrew them and tune them again if they get a differrent room placement.

ports.jpg


I ended up making the grill frames out of cedar left over from my cedar fence construction this summer. After planing and cutting to size, this ended up being an amazingly light, stiff, and strong wood. The perfect thing for grill frames! Here are a couple pictures of the finished cabinets with grills in place.

heil-with-grill.jpg

heil-pari.jpg


I'll now commence on the crossover design. I started looking at it last night, and it will be a bit of a challenge. With 4th order on both the woofer and tweeter, there will be a lot of crap on those boards! It doesn't help that I am planning on using large poly caps and oil caps. Stay tuned for progress on the crossovers!

Mark
 
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