Mr. Ken Kantor, new 3/4" dome tweeter needed for 3 way AR speakers!

[roundhome]

It would be nice to find something that works I have five LST speakers and three LST IIs sitting here with no tweeters shame I would love to listen to them. I'm sure we will have to come up with some thing they won't last forever and then what?

Jim

[RoyC]

The seemingly over-priced AB Tech tweeters would be acceptable if they were truly "drop-in" replacement drivers. I have made $10 tweeters sound quite satisfactory with 3a's (see attached pic), but they required a crossover modification. The better tweeters all require cabinet modifications or adapter flanges as well.

There are more than a few acceptable replacement candidates out there, but in the end the convenience of not having to perform modifications to cabinets and crossovers will outweigh the cost, be it high or low.

The old tweeter was not made of gold, and is probably equivalent to a modern $20+ tweeter.

Roy

[Guest Bret]

>The old tweeter was not made of gold, and is probably equivalent to a modern $20+ tweeter.<

You and I have talked about this many times and we agree that a 30 year old tweeter shouldn't be that difficult to get the better of with new, modern technology. This forum has also "talked" until it's blue in the background about the special performance qualities of the original tweeter (extremely wide dispersion being one).

So. . . I think it might be a little unfair to compare its operating properties to those of a modern $20 tweeter.

I agree that the construction of the old tweeters wasn't what we'd call high-quality today, and is probably eclipsed by a modern $20 speaker. That's an entirely moot point, isn't it?

What I was thinking was; if a *good* drop-in replacement *were* available paying $100-200 for it would not be out-of-line.

I just see repeated calls for a "cheap" replacement option as though "cheap" were a desirable operating parameter. If we can get the right result and get it cheaply, GREAT! If we can the right operating parameters and it's expensive, still GREAT!

I can have a speaker that sounds like a squirrel got caught in the fanbelt of my car almost for free. (you and I have talked this one to death, too)

But the worst situation is where we are badly overpaying for a lousy result.

I'm amazed that so few forum members have read (or believed) the two of us (and others) saying over, and over, and over, that the replacement tweeters were not suitable replacements. It's far more expensive to live and learn than to profit from the mistakes of others.

I'm looking forward to seeing what you guys come-up with as far as a crossover modification. I don't even need a tweeter, but I know the day is coming.

Bret

[kkantor]

Bret,

Thank you! Many end-users just do not think about the realities of business. There is simply no way to bring a tweeter to market for $20 unless:

A- you can sell 10's of thousands.

or,

B- you sell whatever the factory happens to make, without being demanding about specs, quality control, etc.

or,

C- the design is ultra-low-cost, with high moving mass, tiny magnets, etc.

To think otherwise is not realistic. Sorry. It doesn't matter if you can find a factory to make them in China for cost. By the time they are tested, sorted, packed, shipped, taxed, distributed, etc, they are going to cost a chunk. The only way around this is to sell enough to buy bulk raw materials, automate everything, fill entire shipping containers, etc.

Further, large manufacturers do not buy "standard" parts. They just don't. They buy custom parts, and they own their designs. The hobbyist who wants to replace their tweeters with something that is currently produced has one choice: buy something close, and adapt the crossover. We can all hope for better, dream of better. But, the situation is what it is.

Here's a thought experiment: suppose I were to take a classified ad out in whatever audio magazine comes to mind: "Free AR replacement tweeters! You pay only $10 shipping. Limit, four to a customer." Do you seriously think I could empty a warehouse of 10,000 tweeters? It wouldn't happen. I'd get 50 or 100 emails saying, "Here's my order! You saved my life! Can I get ten more?" So that's the first thousand... I would get another 500 emails saying: Dear Mr. Kantor, I was considering buying this tweeter next year, but I would like to know how it compares to the original tweeter, and if you think it sounds more like the AR 3a or the AR 9. Also, would I like an NHT SuperZero more than an AR 2a? How about if I re-capped the 2a?

Don't try this at home....

-k

http://kkantor.spaces.live.com

[mluong303]

Hi Ken,

I have two new AR-303 tweeters on hand. Would you be able to spare sometime to test and come up with a simply crossover design at 5000Hz for this tweeter for flat response plus -3db and -6db for slight roll off so we can adapt this tweeter for the AR-3a speaker? I will sent you the tweeters if it is do-able. If the tweeters blown during experimentation, it will be OK with me. I just don't want you to mess up your own AR-303A speakers for this request. I hope you will come up with a simple crossover design (with available inductor, cap and resistor from Madisound or Zalytron) and adapt this tweeter for the 5000Hz crossover point for the AR 3 way design. I am willing to buy the parts you need and send them to you along with the tweeters. Please let me know and Thank you in advance for your time and consideration.

Minh Luong

mluong303@aol.com

[RoyC]

I agree that it would be impossible to manufacture and market an exact replacement tweeter to sell for anywhere near $20. I was referring to existing off-the-shelf tweeters that cost much less than the AB Tech replacement, and are equal or better in terms of quality and construction to the original tweeter.

In fact, I am becoming increasingly convinced that AB Tech's tweeter is not all that "bad". It has different characteristics than the original, and requires crossover changes to work properly.

My point was that regardless of price or construction quality, no "expensive" tweeter can ever be a viable replacement unless it does not require crossover or cabinet alterations, otherwise there are plenty of off-the-shelf candidates. The more expensive it is, the more it had better be a simple "drop-in" replacement. If not, we might as well continue to figure out how to make the AB Tech tweeter work...at least it fits the hole.

Roy

[kkantor]

Yes! I would be happy to figure out a crossover for the 303 tweeter that works well. Thanks!

If I have Roy's tweeters and the 303 tweeters at the same time, it will make it very easy to create crossover matches for everything.

-k

kkantor.spaces.live.com

[kkantor]

Roy,

I think we are in perfect agreement. Let's get crossovers worked out for what people can actually buy, particularly the AB Tech tweeter. I am convinced that this is the path forward, along with figuring something out for the 303 tweeter.

-k

kkantor.spaces.live.com

[mluong303]

Thank you Ken,

Please email me your shipping address and two AR-303 tweeters will be sent by Priority Mail to you tomorrow morning.

Minh Luong

mluong303@aol.com

[RoyC]

Just checked the tracking #. The tweeters should be there today.

Thanks again, Ken.

Roy

[kkantor]

Minh,

http://www.kenkantor.com/xfer/3aHR_draft_017.pdf

Not yet ready for Prime Time, but soon...

-k

www.kenkantor.com

[soundminded]

The 60 degree off axis frequency response tells the whole story. NONE of the alternatives including AR's own tweeters is anything like a match for the AR3a tweeter. Even just 5 db down, that's a 70% falloff in energy, a subjectively perceived dropoff of about 1/2 loudness. Outstanding and unique as the AR3a tweeter was in this regard, AR's own engineers did not consider it adequate. That is why the side panels of LST were angled, to increase dispersion even further. The lack of dispersion results in less reflected high frequency sound in real listening rooms to balance low and mid frequency reflections, especially from lateral directions. The on axis FR and sensitivity problems exhibited in different tweeters can be overcome with equalization and bi-amplification, the lack of lateral dispersion cannot.

[roundhome]

>The 60 degree off axis frequency response tells the whole

>story. NONE of the alternatives including AR's own tweeters

>is anything like a match for the AR3a tweeter. Even just 5 db

>down, that's a 70% falloff in energy, a subjectively perceived

>dropoff of about 1/2 loudness. Outstanding and unique as the

>AR3a tweeter was in this regard, AR's own engineers did not

>consider it adequate. That is why the side panels of LST were

>angled, to increase dispersion even further. The lack of

>dispersion results in less reflected high frequency sound in

>real listening rooms to balance low and mid frequency

>reflections, especially from lateral directions. The on axis

>FR and sensitivity problems exhibited in different tweeters

>can be overcome with equalization and bi-amplification, the

>lack of lateral dispersion cannot.

could this be acounted for becouse the AR 3A tweeter has a hard dome this would alow for vibrations in a wider area vary simply put but allisons tweeters have a hard dome also

[RoyC]

...and the AB Tech tweeter is recessed in the faceplate resulting in some dispersion and diffraction issues.

Roy

[soundminded]

>...and the AB Tech tweeter is recessed in the faceplate

>resulting in some dispersion and diffraction issues.

>

>Roy

I think this is the correct answer, it is the geometry of the dome. I asked Tom about this once before and he explained how virtually all (other) dome tweeters have a small groove around them. This is comparable to the semi horn loading of the AR9 midrange which improves efficiency (sensitivity) at the expense of dispersion. You get the same amount of sound but it is directed forward rather than allowed to disperse angularly. According to the current thinking of many, maybe most speaker designers, this is desirable, the lack of lateral reflections improving what they call "imaging" but it reduces the optimal listening location to a smaller area, in the extreme a "sweet spot." It also IMO contributes to the shrillness characteristic of modern loudspeaker systems which audiophiles try to mitigate with high capacitance speaker wires, vacuum tube amplifiers, and vinyl phonograph records. (Vinyl phonograph records also have the added benefit that dynamic compression increases the loudness of the end of each musical phrase therefore increasing the loudness of the reverberation tailing off before the next phrase. Audiophiles like this effect.) The hardness or softness of the dome itself is not a factor as long as it does not break up. The soft dome has an advantage over a hard or metal dome as paper cones have an advantage over plastic and aluminum cones in that their inherent internal damping improves their tendency to dissipate the energy of their inherent resonant ringing. (This can be especially bad on metal cone woofers and midwoofers requiring very sharp cutoff filters to surpress it.)

[RoyC]

>The soft dome has an advantage

>over a hard or metal dome as paper cones have an advantage

>over plastic and aluminum cones in that their inherent

>internal damping improves their tendency to dissipate the

>energy of their inherent resonant ringing.

The AB Tech tweeter, unlike the 3a or the later AR-11/12 style tweeter, has no damping material under it, so it is probably a good thing it has a soft dome.

Roy

[Pete B]

Hi Roy,

Those look like tinsel lead in wires if I'm reading

that picture correctly, can you confirm this?

Also, is that an aluminum former, or paper?

There's a brownish color on the inside of the VC

former, looks like ferro fluid, or is the former

burnt from overheating?

Any chance you could measure the VC length as wound,

and the top plate thickness?

Do you know if the AB-tech A and B are similar, or

which one that is in the pictures?

Thanks!

[RoyC]

Hey Pete,

>Those look like tinsel lead in wires if I'm reading

>that picture correctly, can you confirm this?

Yes..to the connectors, which are directly opposite each other.

>Also, is that an aluminum former, or paper?

It appeared to be aluminum.

>There's a brownish color on the inside of the VC

>former, looks like ferro fluid, or is the former

>burnt from overheating?

ferro fluid

>Any chance you could measure the VC length as wound,

>and the top plate thickness?

Sorry Pete, I don't have the tweeter to measure at this point. The faceplate is 1/8" plastic.

>Do you know if the AB-tech A and B are similar, or

>which one that is in the pictures?

AB Tech "A" and "B" in Ken's report are physically identical (#12000840 0613). It is the latest version of the AB Tech tweeter, which has gone through a number of changes. The version I purchased in the mid 90's had a foam covered metal faceplate, and the dome was not recessed.

Roy

[Pete B]

Thanks Roy, your answers make sense, I appreciate your help here.

Looks like a fairly standard 3/4" dome tweeter, besides the low impedance. The tinsel lead in wires combined with ferro fluid should make them a rugged design.

[mluong303]

This is the best candidate to build the economic replacement 3/4" hard dome tweeter for AR-3a and soft dome for the AR-11 if they ever want to get involved and save us from all the wishes and hopes day after day...! The main objectives are to pull back the sensitivity and increase the power handling. Widen the face plate with 3 screw hole openings and level the dome to the face plate with no short horn like the AR9 tweeter.

http://www.zoominfo.com/Search/CompanyDeta...mp;cs=QDEe8p14o

http://www.swanspeaker.com/com/index.asp

http://www.swanspeaker.com/com/htm/base.htm

http://www.swanspeaker.com/product/htm/view.asp?id=31

Minh Luong

[mluong303]

Mr. Ken Kantor, may I send you these two AR 3/4" soft dome tweeters with coil and caps so you can run tests and record the response curves to see the similarity and differences of these two units so people don't just purchase them because they are cheap and assume they are shield version of the AR-303 tweeter! email me your full address so I can ship the parts to you. Thank you in advance for your consideration.

The AR-218V tweeter is different from the AR-303 tweeter. The only similarity is the same face plate dimension and screw holes position. The shield cup of the AR-218V is about the size of the AR-303 tweeter back plate so the magnet of the AR-218V is much smaller inside the cup. The dome sharp of the AR-218V is flatter and the AR-303 tweeter dome bulged up more.

The AR-303, AR-302 and AR-228 were the first three models came out in 1994 and start selling in 1995 which used the same AR-303 tweeter. The AR-218V and other AR speakers for home theater application came few years later in hope for boosting sale that is why you see the '97 printed on the back of the AR-218V tweeter.

Minh Luong

mluong303@aol.com

[genek]

Mr. Ken Kantor, may I send you these two AR 3/4" soft dome tweeters with coil and caps so you can run tests and record the response curves to see the similarity and differences of these two units so people don't just purchase them because they are cheap and assume they are shield version of the AR-303 tweeter!

Carl has run these tests. The results are posted in his "4 ohm 3/4 inch tweeters for sale" thread in the For Sale/Wanted forum. At $10 US it was cheap enough to get one just to play with, and I will be doing some very unscientific ears-only testing on it here.

Carl recommends a .15 mH inductor instead of the .07 mH that Ken recommends for the 303 tweeter, so I think we can conclude from that that this one is not just a shielded 303 tweeter.

[kkantor]

Hi!!

How's everyone doing here? Long time since I've been here!

I'm travelling in China for a few weeks, starting in a couple of hours. If you are not in a hurry, send your drivers along, and I will be able to test them sometime in November. Perhaps, my tech can get to them sooner.

-k

www.kenkantor.com

www.ztamplifiers.com

Mr. Ken Kantor, may I send you these two AR 3/4" soft dome tweeters with coil and caps so you can run tests and record the response curves to see the similarity and differences of these two units so people don't just purchase them because they are cheap and assume they are shield version of the AR-303 tweeter! email me your full address so I can ship the parts to you. Thank you in advance for your consideration.

The AR-218V tweeter is different from the AR-303 tweeter. The only similarity is the same face plate dimension and screw holes position. The shield cup of the AR-218V is about the size of the AR-303 tweeter back plate so the magnet of the AR-218V is much smaller inside the cup. The dome sharp of the AR-218V is flatter and the AR-303 tweeter dome bulged up more.

The AR-303, AR-302 and AR-228 were the first three models came out in 1994 and start selling in 1995 which used the same AR-303 tweeter. The AR-218V and other AR speakers for home theater application came few years later in hope for boosting sale that is why you see the '97 printed on the back of the AR-218V tweeter.

Minh Luong

mluong303@aol.com

[mluong303]

I just got informed that small new shipment of AB Tech 3/4" tweeters and 1.5" midranges will arrive around February. So if you are hoping to purchase the AB Tech tweeters or midranges for your AR 3-way speakers restoration project.

Minh Luong

[RoyC]

I just got informed that small new shipment of AB Tech 3/4" tweeters and 1.5" midranges will arrive around February. So if you are hoping to purchase the AB Tech tweeters or midranges for your AR 3-way speakers restoration project.

Minh Luong

Thanks for the update Minh...

I wouldn't hold my breath . Larry Lagace (Ebay's "Vintage AR") has had these on back order for many months, and AB Tech keeps pushing the date forward.

I am not a fan of AB Tech...Here are a few reasons to add to the comments made by other forum members in the past:

-I recently had an opportunity to examine and test AB Tech's latest $130 "original 12 inch AR woofer". It physically resembles the previous "Tonegen" replacement, but the test results were unbelievably bad! The spider and surround were extremely stiff, as Fs measured 42.2hz (vs AR specs that call for it to be around 20hz). It would be laughable if the woofer were not so expensive.

-ABT continues to sell ordinary $4 8 ohm l-pads as "AR potentiometers" for $13! Such items (usually) fit the cabinet holes, but that is usually where the similarity with the original items end.

-Ken's suggestions have made ABT's $62.50/ea tweeter usable, but the tweeter's strongest attribute is that it fits the cabinet hole. Better sound and higher quality can be had for less than half that price. (Btw, I still have a pair of these tweeters on a shelf...the first $50 can have them both!:-))

ABT, has been the only "official" game in town for many years, but, unfortunately, seems unconcerned about the opinion of those who would like to preserve the sonic integrity of these old speakers. I believe ABT could pay much better attention to the details, and still make a profit.

Roy