Replace tweeter with ESS AMT HEIL ELITE

[c-atle-79bay]

I'm going to try and replace the tweeter on a 3 way tower with ESS Heil Elites or just the AMT module , however wonder how best to do it. My 3 ways are a 4 ohm speaker, the tweeter these would replace are 8 ohm audax that I just don't like that much, and have not lik d with past speakers owned, with an l-pad attached to it. The speakers, Chapman T7 shorties are an open frame design so that makes them perfect for the AMTs. The ESS heil elite is an add on module, which you attach jumpered off the speakers input terminals. I'm not sure of the impedance of the HEIL Elite, but the AMT Inside is 4 ohm if specs are still the same to modern versions for sale, since they use the same diaphragm I'm assuming they are.

I think my best option would be to disassemble the elite and install it in my speakers in place of the tweeter and include the elites crossover network and biamp the whole thing. This would give me the ability to adjust the AMTs crossover value as 1khz or 5.5 kHz, and to adjust there levels as desired. The mid range is a kef b110 who, according to kef is good to 5 kHz. I'm not certain of the crossover vales of the speakers crossover but am going to call the maker and ask.
-if I remove the stock tweeter would I need to replace it with a resistor, or would the l-pad suffice.


The other option is to install as above but connected to the input terminals as ESS instructions advise, although this information is anecdotal as I've not seen the instructions myself.
.-if I remove the stock tweeter would I need to replace it with a resistor, or would the l-pad suffice


The final option I can think of is to just replace the 8 ohm tweeter with the 4 ohm teeter and have it run as the speakers designed crossover point.
- this option would likely influence the speakers crossover values, but to what extent?

Of course I can just play and will do so, but trying to understand exactly what I'm doing to my poor speakers in the process st some point I'd be physically modifying the cabinet to make this happen so I'd like to rake the most sensible approach to my haibrained idea.

Thanks if yor time and knowledge FYI I'm on jury duty so lots of time to think.

 

[Porkloin]

I would think that you would eliminate the existing crossover's tweeter circuitry and parallel the remaining crossover with the Elite's. Even though you're inserting a component rated at 4 ohms in to the place of a driver rated at 8 ohms, I don't think that the impact on the overall impedance of the entire loudspeaker would be as great as one would instinctively think.
I believe that the instruction manual for the Elite has them wired in series with the existing loudspeaker. It may behoove you to leave the existing tweeter and it's circuitry in place and wire the entire Elite in series. The overall impedance would be a bit higher, but that's a safer solution.
What I can't figure for the life of me is where you'd mount the Heil on the T7. They don't appear to be as "open frame" as the models that ESS put them on and it would be a crying shame to see their dipoley goodness bouncing around on the inside of any cabinetry.
How about building a new enclosure for the Elite guts that would match the Chapmans? Maybe you could hop a ferry over and get Stuart to build you something custom.

 

[c-atle-79bay]

I'd never thought to do them in series, you don't happen to have a digital copy of that manual available do you, if so could I please have a copy? I've tried them parallel and the amp, just an AVR seemed to handle the combo, but nothing was matched, I've since received new diaphragms from ESS (for some reason he sent them without payment so need to level up with him) so I'll be able to have both speakers exactly the same.

The T7 shorties are the first version and quite a bit different. I've got a thread on them, but this seemed a subtopic. I can remove the tweeter baffle and install them in place but will have to raise the tops by about 3/4 of an inch.

I have to stay away from the island too likely to come home with a pair of newer ones.

 

[Porkloin]

I wish I could remember where I saw that. The only thing I have in the collection at the moment is a schematic.
That speaker looks like it was made for a Heil on top.

 

[HyKlas]

I disconnected the horn tweeter in my Sentry III speakers and ran that exact Heil sitting on top. What I did was bypass the Heil internal crossover and ran a car audio (4Ω) 3.5kHz 2way crossover with an L-pad. It's not perfect but it works very well. Still have yet to sweep it... Who knows? Maybe there's a hole I'm not hearing or it's totally out of balance.

You could do the same but you need to find out where your crossover point is. If you run it from the original 8Ω tweeter wiring you'll shift the crossover point to some unknown which will probably not mate well with the mid.

 

[c-atle-79bay]

I've never done a sweep but my neighbor has, might be practical to do. So I"m reading in other posts, perhaps misunderstanding, of making a 4 ohm driver appear as a 8 ohm driver by adding a resistor in series, however other sources say the resistor would be HUGE. Man this stuff gets confusing. I also reached out to Stuart, awesome person, to see if he can provide the schematic or crossover points. It also seems depending on the crossover type, the replacement of the 8ohm with a 4ohm could make more or less difference. SMH These designers are truly artistic wizards.

 

[Porkloin]

Putting a 4 ohm driver into a crossover meant for an 8 ohm driver halves the crossover frequency. If the existing crossover crosses the tweeter over at 5000 Hz., it would cross a 4 ohm driver over at 2500 Hz. The Heil is rated at 2.9 Ohms and the crossover point I read on the T7 specs is 3200. It would cross over the Heil roughly at 1160 Hz at 18 db. per octave, which is higher than ESS crossed them over, but not by much. Conventional wisdom has been that the Heil is pretty anemic below 2500.
An easy thing to do would be the addition of caps and coils to the existing crossover. You want to increase the value of the capacitors by the same percentage as you decrease the value of the inductor coils in the tweeter leg. This can be accomplished by paralleling additional parts to the existing components.
For example, if you were to parallel each of the cap/coil segments with like value components, you would be crossing over a 4 ohm driver over at the same frequency as the original driver crosses over with the original configuration. You'd probably have to add a 2 ohm resistor in line with the hot wire to the Heil.
I'd be curious to see a schematic of the T7.
Another easy alternative would be to disconnect the tweeter leg of the T7 crossover and substitute with the Elite components. The problem is that the ESS crossover points may leave you with a big frequency hump or valley with the T7 midbass driver.

 

[c-atle-79bay]

Thank you Porklion, I like your diagram, violet and blue perfect ESS. I've asked Stuart for a copy of the schematic or the crossover points of the old T7, have one other source to ask as well. Thankfully the cross over is very accessible. I tried to measure the impedance on the Elite and it measured as 1, adjusting the L-Pad did not change this, not certain why this is the case, multi-Meter is working based on testing other speakers, and the Elites work other than the output is low on the one with a visibly damaged diaphragm. I'll change them out tonight and try in place of stock tweeters just to see how they sound since I have them all the way out. They are super easy to take in and out so if have time will try also as elites wired in series vs. parallel.

 

[c-atle-79bay]

On the idea of recreating the ESS crossover, could I change at the 5k leg CAP to better match the crossover points of the Chapman mid? I have no issues running this setup bi-amped as I'm just using the AVR for 3 channels and even then I think I like the sound placment better with 2 channel.

 

[Porkloin]

If you're trying to measure "impedance" with a regular volt/ohm meter, you'll get nowhere in a tweeter circuit. You're trying to measure DC resistance when there's a capacitor (or capacitors) in line that do not pass the DC current from the meter. You'll get a reading of infinite resistance. If you bypass the crossover and measure the Heil directly, you should get a DC resistance of 2 ohms.

 

[Porkloin]

On the idea of recreating the ESS crossover, could I change at the 5k leg CAP to better match the crossover points of the Chapman mid? I have no issues running this setup bi-amped as I'm just using the AVR for 3 channels and even then I think I like the sound placment better with 2 channel.

There you go. Easiest solution yet.

 

[Porkloin]

I suppose NOTHING is easy when you're modifying the original equipment. You'll still need a bit of measuring to make sure you haven't created some peaks or valleys that you may eventually psych yourself into accepting.

 

[c-atle-79bay]

Good excuse to get a microphone.

 

[Porkloin]

It's always good to see a Heil going to a better platform than ESS was able to provide. I only wish I had the time to devote to pairing mine with one of the great full range drivers available out there.
Did I say time? I meant time AND money. Setting up to develop a crossover for such a venture would be costly. More amps, an active crossover, measuring equipment, a fist full of caps, coils and resistors. I had the privelege of getting some help on a project back in the 80's from a local speaker genius who looked at the measurement graph and just knew which parts to insert in the crossover. to flatten that line out.
Did I say time and money. I meant time and money and know-how.

 

[c-atle-79bay]

I have none of those things, well time right now, but that's about it. Think I'm going to mod the elites crossover. The l-pads are already very scratchy almost unusable, and closed, so difficult to clean, and the crossover visually is dead simple, I can hack it if all I have to do is swap a cap, so just have to wait for info on the 3 way crossover points. Now to work on the knowledge, which I really appreciate your and others help here at AK. Always helpful folks. Hard part will be what speakers to sell when I phyced myself into liking something more than the rest.

 

[c-atle-79bay]

My plan at this point, after help from this thread, is to gut the Heil Elites, remove the tweeter baffle and mount the AMT in its place and attach the Elites crossover on the back of the speaker and run it in a bi-amp configuration. I will just deadend the stock tweeter leads for later use is needed. The Elites crossover had 2 crossover points, and an L-Pad. I need to replace the L-pads anyway so I'm going to work on figuring out the correct crossover points to match with the KEF B110 mids.



Porklion provided a schematic, can someone recommend an online tool for reverse engineering the crossover to help figure out the cross over points? Altough not certain if I’d really want to have points in this configuration, not certain if there would be times it would be nice to have more frequency overlap vs less.


Thanks

 

[c-atle-79bay]

Replaced my diaphragms yesterday both in pretty bad shape. Sound much better now. Also determined output issues related issues to a bad fuss holder, if I wiggle it the output changes but still feel the load has issues. I also have them sitting on top of the chapmans crossed over at 5k and they sound pretty good, still getting use to the sound. Has to be a gap but going down to 1k Justina does not sound good to me.


One question about inductors on the crossover does the location matter? Can I have them bunched together with the rest of the crossover?

Thanks

 

[Porkloin]

One question about inductors on the crossover does the location matter? Can I have them bunched together with the rest of the crossover?

Thanks

Some actual empirical evidence in the audiophile world: http://www.troelsgravesen.dk/coils.htm
As it turns out, not only is the distance between inductors a factor, but also their orientation to one another.
Screw cap fuse holders cost next to nothing.

 

[Bratwurst7s]

...can someone recommend an online tool for reverse engineering the crossover to help figure out the cross over points?...
Thanks

Not "online" in that it's an internet active tool but downloadable for free. Works pretty good.
http://www.diyaudio.com/forums/software-tools/259865-xsim-free-crossover-designer.html

Cheers,
James

 

[c-atle-79bay]

Thanks James, will give it a try. As it stands, the elites are turned all the way down and a bit too loud at 1k, when I go to 5k they are WAY to loud. Overall am still trying to physic myself into liking it. think I need to get the other stock tweeter, seller has one for me just have a two hour trip to get it.