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Author Topic: New "crossover" schematic and diagram  (Read 51178 times)
Capt. Z
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« Reply #15 on: October 12, 2012, 01:55:52 PM »

Just looked on the writing on my coil.

Monacor; 1.0 mh; 0.85 mm; 0,65 ohm

Looks like me coil wire is a little thinner and has higher resistance then what you've been using.

What difference would that make?
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greenvalve
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« Reply #16 on: October 12, 2012, 02:27:43 PM »

The C-Coil inductors have a DC resistance of less than 0.07 ohms. If you parallel two Fostex drivers, the resistance would drop even lower, increasing max wattage before the Heil melts. I like the idea of an MTM.
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Ed Schilling
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« Reply #17 on: October 12, 2012, 04:36:43 PM »

Buzz, we don't want the system resistance to go lower. I'm not sure if that is what you mean but I don't see how paralleling 2 drivers will lower resistance of the coil, if that is what you mean also.

Keep in mind, I'm not trying to build new systems and am only interested in marrying the Heils to the Horns. Heil meltdown is not an issue at sane outputs. We also don't need more output from the 126.

While you may be correct in your "math", you may also not be correct in the overall result. I seriously  doubt the difference in a fraction of an ohm will be audible. And if it results in less output from the Heil and more from the 126 then it will not be the direction the system needs to go in.

All that said, you have a pair of Horns, Heils and ears Smiley Let us know what you find out if you do the actual experiment. Please do keep in mind it's quite possible to screw with stuff like this forever and that too is not what we want!

I only went down this path because I did not have suitable caps.....I liked the result and the fact no one has to buy anything to test the difference.

Capt.Z, don't listen to Buzz ( Smiley ) and do not worry about your coil, it sounds ok, right? Smiley

Ed
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jpax
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« Reply #18 on: October 12, 2012, 05:38:49 PM »

have had the horns about a month, burning in. wrote a floral, purple prose description last night. erased it. substitute: it is like watching an extremely beautiful woman very, very slowly undress.
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greenvalve
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« Reply #19 on: October 12, 2012, 07:22:44 PM »

Paralleling two drivers would allow the use of less inductance for the same crossover frequency. The lower resistance protecting the Heil comes from the paralleled drivers, more than the lower resistance coil. I need you to make me another pair of horns so I can stack them, seriously.
« Last Edit: October 12, 2012, 07:26:01 PM by greenvalve » Logged
steve f
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« Reply #20 on: October 12, 2012, 07:57:01 PM »

Buzz,

I suspect to get a major difference it may take more than that. Remember that Ed tried and rejected stacked Horns opting for the model two horns instead. When I built a high efficiency two way, I stacked my 126 only Horns on top of each other for one channel and stacked my two ways on the other. Efficiency was very close, with my two ways having wider band-with. In any case, the two ways worked great stacked, but were imposing objects in the room. Ed was right. The Horns didn't work stacked. I put them side by side and they were much better. I don't know why.  When I split the system and ran a Horn per channel stacked with a large two way upside down on top, the sound was great.

I strongly suspect that the Horns would sound great with a model two and stacked Heils, with either another pair of twos on top or at least a pair of 126en's in boxes, not baffles, on top. The only time I heard model three's, they sounded really dynamic. I don't think one pair of Heils will provide enough volume with four 126 drivers. A stacked pair should.

Man, its really easy for me to tell others how to spend their money.  Wink  But I'll bet a fancy pair of $50K speakers won't be better.

steve   Cool
« Last Edit: October 12, 2012, 07:59:00 PM by steve f » Logged
Ed Schilling
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« Reply #21 on: October 12, 2012, 08:05:45 PM »

Buzz, yes on the inductance thing but "no" on the parallel drivers. System impedance then too low, I think.
Henry has 2 drivers in his M2's and my guess is the he'll let us know which sounds better. Normally I'd go for parallel but in this case series might be a better load for most amps. I have 2 of Henry's M2's and will eventually figure the value for them. Do keep in mind only a handful of fellows have M2's and just a couple have the Heils so I have not jumped on this. The standard xover was easy to modify for the M2, this is a little different.

You know I have stacked the Horns vertically before, right Smiley? It sucked, compared to the M2's. Sticking a Heil between them may work, who knows.

Joe D'Appolito invented the MTM to achieve a set of goals. The design simply does not work as he intended (or properly) unless built as he designed it, using his theory. I have his original article if you'd like to read it. An improper mtm is not as good as conventional placement in most cases. Of course, this does not stop fellows from building things they do not understand and liking the results. I get a kick out of seeing "improper" mtm speakers and thinking "they don't have a clue".  It's not as simple as sticking a driver between two others, but again, people that do not know better do it all the time. He came up with that topology for a set of reason and unless implemented properly those  reasons are not achieved.

A proper mtm is a damn good thing, an improper one just looks like a good thing and is no better and maybe worse than conventionally placed drivers.

But hey, what would I know, I'm no rocket scientist!
Ed
edit***** Many, many years ago I wanted to build a proper MTM. In order to get the driver spacing correct I had to cut the faceplate on my beloved Dynaudio D-28 AF. Sure, I could have not done it but I figured if you are going to build it then it should be built properly. Such a small difference it seemed but again, to do it properly that was what needed to happen. They sounded fantastic. Too bad we can't by the D-28 anymore.

« Last Edit: October 12, 2012, 08:58:47 PM by Ed Schilling » Logged
steve f
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« Reply #22 on: October 12, 2012, 09:12:47 PM »

For a true MTM, driver spacing and crossover slopes are critical. Lots of them are done wrong. Even Joe D' rarely uses that configuration.

I was kind of suggesting an arrangement like the Morel Octave Twin, which was a two way doubled up. I do wonder if the Heil can support four woofers. I don't think so. I bet the crossover would be a PITA too. I always liked the M2. It was an easy and flexible load for most amps.

steve
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Capt. Z
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« Reply #23 on: October 13, 2012, 04:24:13 AM »

Erik;

You got those wonderful subs.
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greenvalve
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« Reply #24 on: October 13, 2012, 04:26:31 AM »

Stacked, or side by side, my hope is that the parallel drivers would give a little more bass weight, and protect the Heils at high volume. Like Steve said, the crossover could be a pain. Using just the single inductor would be the only acceptable solution worth bothering with. What i hear is, taking the cap out of the signal path has made an improvement in vocal clarity. Is this because the corner frequency the inductor provides is not fixed? The more current fed the Heils, the lower the slope becomes, as the resistance of the Fostex+inductor pushes that current at the Heils. Ed, you are not gonna be able to play your Madonna at 100db+ without that cap, but you will want to. Wink

Dieter, the 'capless crossover' is a nice improvement for low volume listening, just as Ed claims. I am trying to find my own solution. Since I do not have corners in my large listening room, I need to have more output from the lower octaves, at higher volumes. The greater high frequency extension that the Heil gives, compared to the Fostex, makes this even more noticeable in my room.
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greenvalve
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« Reply #25 on: October 13, 2012, 04:30:41 AM »

Yes, Dieter. But I need the fast mid-bass too. I like the low DCR Jantenzs.  Wink
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Capt. Z
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« Reply #26 on: October 13, 2012, 04:34:18 AM »

Over here I only was able to get the Monacor for a decent price.
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Ed Schilling
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« Reply #27 on: October 13, 2012, 06:40:35 AM »

Now Buzz, do you really think that I'd have not checked and tested all this before I put it on the forum Smiley?
When I get going, things happen fast. I don't need weeks to get to the bottom of things usually.

This is another case of "theory not being reality". I have seen no issues at all and high outputs are just as they were with my CFA.

You'll only melt a diaphragm if you try really hard. I've not actually played Madonna yet but Primus at realistc levels is just fine.

I did mention, I think, that I am a little unsure of high power amps at high levels but "safety" is certainly not an issue with what most of us use. The max output before distortion is not lower than before and high outputs with big amps were always more dangerous than with our low power tubes.

I will admit that a 6 db slope (with just a cap) will not protect the Heil unless the xover point is very high, which wastes most of the "goodness" of it. This does not seem to be the case here. I suspect the 126 is sucking more current than one would think.

Another consideration is the power handling of the 126 itself. It's not like it's "megawatts". Now if one had a driver that could handle say 100 watts then the safety would be an issue for sure because you'd be able to play the system much, much harder. My guess is the VC in the 126 will open long before the Heil is heated up. It'll act like a fuse.

I think I also said something like "this scheme works here because of the particular drivers and probably is not suitable for most". (I did not read through all this to make sure, but I think I did mention that).

Doubling the drivers will lessen the chance the 126 will become a fuse, which is not a good thing, but again, at sane levels it should not be a problem.

I think so long as everyone is aware we are going for "clarity over output" and do not abuse the system by "going for output until something breaks" we'll be fine.

Buzz, I'm glad you're bringing this up and appreciate your thoughts and experiments, I'm just a little less worried about the safety than you are, but it is a concern for sure. I sure as Hell do not want reports of "I smelled a sickly sweet odor while playing Norah Jones" Smiley. I could not get it with my CFA and Primus, and trust me I tried Smiley.

Have you added a cap to the circuit to make it a proper series network? I was not happy with that.

Ed



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Pit Hinder
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« Reply #28 on: October 13, 2012, 07:41:43 AM »

OK, just to mud up the water - two comments from over here (and I won´t comment on the weather we have here, I´d have to use very rude words).

Every MTM = D`Appolito, as claimed by sales executive illiterate dumbasses?
  Shoot me dead with a BB gun to make me laugh. Keeping the drivers phase coherent within that wide frequency overlap is a worse chore than making your mother-in-law love you, and you won´t find that kind of drivers in the dumpsters those idiots obviously get theirs from.

And overloading the 126...oh boy - you need to be deaf, and drunk as a skunk.
  The power ratings Fostex give in their spec sheets must be measured under some Samurai norm. You´ll never cook a Fostex before your ears have given you an incurable pity trauma.

Just two comments, as promised. None about the coil´s tiny resistance probably being outside the "possible problem" envelope, as it can´t influence the Horn´s Qt in any perceptible amount. Using a cheap rattly coil might, though.

   Pit
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Henry
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« Reply #29 on: October 13, 2012, 08:27:13 AM »

So far with the Model 2, I've only run the Fostex drivers in series giving the system impedance of a little over 15 ohms.  I've listened in this configuration for a short time before I left town and I felt that I better leave it alone until I try the 16 ohm taps on my amp (requires some soldering and I had no time Sad).  They did sound good though.

I will try the parallel configuration as well, to see what happens.  Or... I could occupy Leesville soon and bribe Ed to drop everything for an afternoon while we play with my orphan Model 2's. 

I'll be suited up in anti-spider gear.  Wink
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