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Old 28th February 2005, 06:32 PM   #11
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Go to the Adire website and check out the XO for the HE12.1, which uses the Beta 12CX and an Adire compression tweeter that seems to be a modified APT-50. There's a lot going on in that crossover I built the HE12.1, then tried a direct replacement of the tweeter with the Selenium DT150, with mixed results. I got the greater treble extension I was looking for. But I also had a pretty bad peak, bad enough that I could see it with my Radio Shack SPL meter. This was back when I didn't have a mic, hadn't started using Speaker Workshop, and basically knew much les than I know now (which is next to nothing). So I pretty much futzed the crossover by ear. I was happy with the results for a while, but ultimately decided to move on to something else. My HE12.1 is now used as a woofer in a 3-way system:

Click the image to open in full size.

I added an open baffle on top and put a midrange and tweeter on it. I think this sounds smoother than my hacked-up HE12.1, but it also costs quite a bit more.

I haven't tried the Beta 12CX in an OB. Let me know how that works out if you try it, and then maybe I'll try it too
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Old 28th February 2005, 06:41 PM   #12
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Default Re: Autotuba

Quote:
Originally posted by tiroth

The Autotuba seem to have that livelieness that I associate with high efficiency. They don't go super-low without EQ though. I am trying out a 16" version to see if I can squeeze a couple more Hz of low-end out of them.
I'm seriously thinking of a pair of autotubas in my rig as well. I have a pair of NHT1259's I can use, but if you're going high-ish efficiency, it seems counter productive to use normal subs. Interpreting the AT response chart from a car is tough though, and it's not immediately obvious how much and what type of EQ is needed to flatten them, particularly when room gain is included. If I remember correctly, they're down 10dB or so at 35 Hz from the peak at ~100-120, although that still means 93-95dB/W.

In my room, my lowest mode should be ~35Hz, so I'm counting on room gain helping out a bunch below that. Are you corner loading it? I'm not sure that going to 16" will give you much. but I guess every little bit will help?

What's you take on max output? I was considering the PE Quatro driver simply because I order from there all the time, and the MCM driver is sporadic in availability. The PE gives up some xmax, and so has lower max output. Not likely a problem in the home above 40HZ, but might be below that.
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Old 28th February 2005, 06:54 PM   #13
tiroth is offline tiroth  United States
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I will post some Autotuba measurements in about 2 weeks. I have preliminary measurements, but I have been holding off because I hesitate to publish something that may not be 100% accurate. Your remarks are quite accurate from memory though...I think the estimates on corner loaded efficiency may be a bit optimistic below cutoff.

The difference between 14" and 16" will not help much, but it is 30% more mouth area, so it should make some difference.

My measuring has been slowed down by the fact that I gave the first completed sub away almost immediately after finishing it. I have two more that are almost finished now, just need to cut the gasket plates. A bit more of a delay though because I want to prep for veneer before installing the drivers.

After experiencing chest pounding bass from my MD player + Sonic Impact amp (maybe 3-4W into the nominal 16 ohm load), I had to at least try an AT in the system. (this was with the AT full range though--so it is cheating a bit)
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Old 28th February 2005, 07:02 PM   #14
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Yes, Adire was initially using a modded Eminence compression tweeter in their HE kits, but they have since upgraded to a proprietary driver of their own. You might want to give them a call to find out in what ways the new one is better.

I too am anxious for GM's response about the necessity of Adire's XO if we are going active.
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Old 28th February 2005, 08:14 PM   #15
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Greets!

In scanning the thread I missed the 'active' part, so 'never mind'.

That said, a compression horn is ~resistive in its passband so wants to 'feel' a matching one, ergo a RC network in series to flatten its response/'lift' up the extreme HF should be used IMO unless a high output impedance amp is used. The non-inductive resistor value should be whatever the driver's nominal impedance is and PIO is the preferred bypass cap's construction.

Once you're satisfied with the HF's response, then level match them separately at the listening position and you're ready to find the XO point(s)/slopes that yields the smoothest transition. Though some folks say you can't hear enough difference this high up to bother with TD, I recommend you at least try it so all that's left is to dial in the HF's TD using either the XO point or its acoustic equivalent (octave average between the two).

Or save yourself all this measuring/effort and just bi-amp Adire's kits.

GM
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Old 1st March 2005, 12:11 AM   #16
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Default doing kindof this

hello.
im in the same boat.
Got some ht10s but found that the tweeter wasnt up for a really loud evening at the local bar.Had to change them to some BMS drivers.I dont know the results yet.Got to modify the xo.
The adire tweeter is good for home use but it looks more like a "supertweeter" than a true compression driver.Sounds good but cant handle pro use.
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Old 1st March 2005, 02:07 AM   #17
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Quote:
Originally posted by mpmarino
I'll look at the selenuims.
Good bang for the buck. I'm happy with what I have of theirs, 15's, coax 15's and comp drivers.

Quote:
[i]GM,I've seen your posts and I have a feeling you are quite talented in speaker design. [/B]
That's 'cause he's really old and has been doing it since he was, like, two.

Actually, you'll hardly find a more knowledgeable person around. He's probably forgotten more than some of us will ever know.

Cal
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Old 1st March 2005, 01:42 PM   #18
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Those Seleniums are only ~$24us at PE! Replacement coils ~$15us! You can even get them with a plastic horn for a couple dollars more. Hmm..quite cheap. How is the build quality? Is any special hardware necessary to bolt 'em to a betaCX? They kind of look like cheap plastic piezo type things..are they?

Man, the replacement domes are so cheapo it almost makes me want to go with those and try some mods/dampening. You know, a little trial and ERROR.

Sorry for all the questions and thank you.

Marc

Quote:
That's 'cause he's really old and has been doing it since he was, like, two.
Ha ha..GM, were you a pro in the industry or a long time DIYer?
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Old 1st March 2005, 03:09 PM   #19
GM is offline GM  United States
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Greets!

> That's 'cause he's really old and has been doing it since he was, like, two.
====
They say 'old' is a state of mind, in which case I'm a barely responsible youngster, but I look in the mirror and wonder who the old fart staring back at me is and my body's decrepitude implies I'm far older than my actual 59.

Actually, I 'built' my first speaker at age 8 when I noticed that an oval driver stuck in a Kleenex box would make a neat looking speaker. The rest as they say, is history.
====
>Actually, you'll hardly find a more knowledgeable person around. He's probably forgotten more than some of us will ever know.
====
Trust me, there's lots of folks far more knowledgeable over a broader range of audio topics than me. I'm more a 'jack of trades, master of none'.
====
> Ha ha..GM, were you a pro in the industry or a long time DIYer?
====
Off and on long time DIYer, though I did occasionally design hi-perf annunciator systems as part of an electrical distribution controls contract. Really, most of what I know about audio design is stuff I learned designing various things like hi-perf slot/RC cars and vehicle intake/exhaust systems, seismic, mining, crane, and Naval shipboard rated electrical controls/enclosures, electrical control command consoles from small conveyor control panels to the room sized systems like you see at electrical power plants, etc..
====
> How is the build quality? Is any special hardware necessary to bolt 'em to a betaCX? They kind of look like cheap plastic piezo type things..are they?
====
No personal experience so others will have to enlighten us, but I doubt they're piezos.
====
>Man, the replacement domes are so cheapo it almost makes me want to go with those and try some mods/dampening. You know, a little trial and ERROR.
====
Go for it! This is how I learned much of what I know since I'm too math challenged to understand the math in textbooks, etc., though in this case it wouldn't get you very far. Anyway, THIN coatings of Dammar or similar (not much excursion capability in a compression driver before it slams the phase plug!) can really smooth it out, though the HF rolls off somewhat. Shellac or similar that dries hard can be used to increase the HF, so finding the right 'mix' of the two WRT their placement on the diaphram can yield significant improvement. This of course also holds true for point source cone/dome drivers.

Depending on the construction, damping the exterior can help, as does experimenting with front/rear chamber Vb since they are optimized from the factory primarily for efficiency.

GM
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Old 1st March 2005, 07:40 PM   #20
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Quote:
Originally posted by mpmarino
They kind of look like cheap plastic piezo type things..are they?
Marc,

"The DT150 is a 1" phenolic dome compression driver specially designed to offer a smooth extended frequency response over a broad band, from mids to highs, with very high efficiency. Ideal for compact two- and three way systems which require uncompromising performance with high power output and superb frequency response. It also features a compact 4" x 4" ABS horn lens. * Power handling: 75 watts RMS/105 watts max (conservative, with recommended crossover at 4,000 Hz) * Voice coil diameter: 1" * Impedance: 8 ohms * Frequency response: 1,500-18,000 Hz * SPL: 107 dB 1W/1m * Dimensions: 4" W x 4" H x 4-3/4" D. "

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