Radial(Tangerine) versus the regular circumcerential phase plug

[Old Guy]

IMHO the Tangerine is slightly better then the better crossover, so 1+1=2, a noticeable improvement.

[voice of the theater]

IMHO the Tangerine is slightly better then the better crossover, so 1+1=2, a noticeable improvement.

Thanks, I always thought that the Tangerine was a pretty significant factor to the improved h.f. response of the 19's, but didn't have much in the way of comparative experience to go by. I just based that opinion on the Altec literature and my own ears comparing the 19's to Valencias and two pair of Altec P.A. speakers I've owned in the past (one pair in home made cabinets with 807-8A drivers and a pair of A7's with 806-8A drivers) and a pair of Heathkit AS 101's I used to own.....

[whitebroncoii]

As someone else has said; there is likely a measurable improvement with the Tangerine phase plug. It is probably not sonically noticeable. The marketing from Altec about 20kHz is just hype. Review any data sheet for any HF driver and look for the plane wave tube response graph. Both 1" and 1.4" drivers have a significant hump in the middle of the response. The Tangerine phase plug may have added a couple of dB at 20kHz. Since the output is 15+ down from the peak output, it makes very little difference. A lot of work goes into the crossover design to push the hump down and boost the extended highs.

IMHO the crossovers and diaphragms in the Model 19 and Valentia will make more of a difference.

[bfish]

Of interest are the objectives of the Tangerine design as stated by the inventor (Henricksen) in his patent (abbreviated);

easier/cheaper to produce
improved efficiency/lower distortion
plane wave output

No mention by the inventor of extended response (that came from the marketing dept).

My opinion:
The Tangerine phase plug was designed for MR horns...

The coincident timing of Tangerine and MantaRay developement agrees. I suspect a MantaRay would hardly work as designed if driven by a spherical wave.

sidebar
Henricksen also specified the slit count should be a prime number...

Added
OG, I have an affinity for obsidian too, but mine is because of the relative ease of working (5.5 on the Mohs scale).

[Ronald Lee]

bfish: I wholeheartedly agree. Anyone can make a thing with enough money, but it would be a real stroke of genius to achieve the something by spending the minimum of money.

[voice of the theater]

.........Can we actually hear a sonic difference between the two phase plug designs, I know they can measure it with instruments. I am not against the new plug, I am all for cheaper, without any performance degradation. I am just curious.

I won't lose any sleep if it turns out that the Tangerine doesn't make much of an audible improvement--but this thread has got me curious to know for sure (if possible) the answer to this question since opinions seem to be all over the map and I've believed that the Tangerine was the best innovation since sliced bread.

As someone else has said; there is likely a measurable improvement with the Tangerine phase plug. It is probably not sonically noticeable. The marketing from Altec about 20kHz is just hype. Review any data sheet for any HF driver and look for the plane wave tube response graph. Both 1" and 1.4" drivers have a significant hump in the middle of the response. The Tangerine phase plug may have added a couple of dB at 20kHz. Since the output is 15+ down from the peak output, it makes very little difference. A lot of work goes into the crossover design to push the hump down and boost the extended highs......

I'm not looking to start a big debate, but wanted to see if I could find any evidence online that would support either opinion ("significant improvement" or "not much if any of an improvement") about the Tangerine. I looked online for a plane-wave tube response graph (as mentioned by whitebroncoii) for any driver that uses the Tangerine phase plug and couldn't find one. In fact, I couldn't find much online as far as specs on the 802-8g anywhere, but here is a quote from the Altec 902 spec sheet which also uses the Tangerine plug.

"Altec's new Tangerine radial phase plug refines the technology of proper phasing, ensuring maximum high frequency reproduction while maintaining smooth overall response. The drivers are capable of uniform, peak free reproduction throughout the range of human hearing." And under specifications for the 902-8T it says "Frequency response uniform....from 500 Hz to 20kHz (902-8T)."

http://www.altecpro.com/pdfs/vintage...%20Drivers.pdf

Now, this spec sheet doesn't show any test results/frequency response curves, so to me it's not gospel. It contradicts what whitebroncoii said about the frequency response of these drivers but it provides no evidence.

...Both 1" and 1.4" drivers have a significant hump in the middle of the response. The Tangerine phase plug may have added a couple of dB at 20kHz. Since the output is 15+ down from the peak output, it makes very little difference....

So, I guess what I'm getting at with this post, is asking you (whitebroncoii) or anyone else out there a favor. Any chance you could provide links to "any data sheet for any HF driver and look for the plane wave tube response graph. Both 1" and 1.4" drivers have a significant hump in the middle of the response." If you have links to sheets for the 802G or 902 or any tangerine phase plug drivers that we could compare the frequency response curves to sheets for an 806/similar circumferential phase plug drivers it would be phenomenal for me and anyone else out there looking for some type of evidence regarding this question (to see if there's a trend that the tangerine drivers all have flatter/extended hf responses compared to the circumferential phase plug drivers). If I could see the (officially published?) frequency response curves and compare for myself it would go a long ways to either confirm what I've believed about how great the Tangerine phase plug is or to refute it as as mainly marketing hype..... whitebroncoii, I see you're in Oklahoma City--I'm not prejudiced but that makes me think that maybe you know of some links/data that many of us aren't aware of or maybe you have connections locally that have data/links I can't find online? Or maybe your location is just coincidental?

Of interest are the objectives of the Tangerine design as stated by the inventor (Henricksen) in his patent (abbreviated);

easier/cheaper to produce
improved efficiency/lower distortion
plane wave output

No mention by the inventor of extended response (that came from the marketing dept).

Do you mean to suggest that someone in a corporate sales/marketing department may have embellished to improve their sales? I've never heard of such behavior!?:snickerpup: (again, some frequency response curves that whitebroncoii mentioned would help answer this question--so we can see whether or not there's a trend that Tangerine drivers in general have a much flatter/more extended hf response than their circumferential counterparts)

The coincident timing of Tangerine and MantaRay developement agrees. I suspect a MantaRay would hardly work as designed if driven by a spherical wave.

Really, the Tangerine was designed for use with the MantaRay Horns? But didn't Altec use the Tangerine with sectoral horns before they used it with the MantaRay? Or am I way off as far as their timeline goes?

[Panomaniac]

Maybe we should just measure a few?

[voice of the theater]

Yes, if it turns out there aren't many/any officially published curves available online for comparisons, that would rock! Even if there are enough officially published curves ("Review any data sheet for any HF driver and look for the plane wave tube response graph.") to look for a general trend/pattern as far as whether or not there's a flatter/extended frequency response with the Tangerine drivers, it would still be interesting to see how the officially published curves compare to current measurements of 20-40 year old drivers....

[bfish]

There's a plane wave tube plot of a Tangerine-equipped 909 on p2 at;

909-8A-16A COMPRESSION DRIVER

The notes on p3 must be considered for interpretation of those plots (plus an understanding of the inherent on-axis differences between exponential and constant directivity horns).

I think I remember PWT plots for some circumferential-plug drivers in one of the old tech letters...

Added
The best "fair" comparison would be an 802D vs 802-8G (or 808-8A vs 8B) with the same diaphragm under the same conditions. Might as well run both with/without loading caps too.

[whitebroncoii]

OK guys, many of you are absolutely positive that 416s and 515s go down to 8Hz and that the 802A HF driver can go out to 102kHz. I know it is hard to believe that you might be wrong. However, here are a few thoughts. Please be nice and don't put out a "hit" on me. This is the truth as I understand it after working for Altec over 15 years;

All of the 1.75" voice-coil HF drivers with aluminum diaphragms (800/900 series) have very similar frequency responses. The smaller magnets (806) simply have a couple dB less output. Diaphragms are interchangeable in all of these drivers. There is virtually no sonic difference between the 802/902 diaphragm and the 909. The 909 simply handles more power.

The early horns will "beam" on-axis (coverage narrows) as frequency increases. Frequency response measurements on-axis (directly in front) will seem better above 5kHz compared to an MR horn because of the beaming. These early horns did not do a good job in the install markets due to the relatively poor coverage. Please keep in mind that Altec's primary market was installed sound, not home hi-fi.

Electro-Voice engineers developed the constant-directivity horn in the mid-70s and Altec had their version by the later 70s (Mantaray). The advantage with the constant-directivity horn is better coverage. The disadvantage is the on-axis output is spread over a larger area and frequency response "droops" above 5kHz. Crossovers (passive and electronic) required a "horn correction" boost to flatten the response of an MR horn. Please review the 909-8A data sheet from around 1989. No "horn correction" has been applied for these measurements. Figure 1 (plan wave tube) clearly shows the "hump" that I mentioned. This hump is also obvious in figure 3 (MR944A horn) and figure 4 (511B horn). Speakers using these same horns will have "horn correction" applied in the crossover and response curves will be flatter. The generic crossovers (N500, N800, N1209, etc) will have less correction versus a Model 19 crossover.

Remember what I said, all of these drivers have similar measured frequency response. Now, let's talk about published frequency response. Looking again at figure 4 of the 909-8A data sheet, response is not flat. If we select the peak output as a reference, the output at 500Hz and 20kHz is over 10dB down from the peak. Yet the text of this same data sheet says "Frequency Response: 500Hz to 20kHz". Gentlemen, this is called marketing and it is abundant in all speakers and speaker products. The data sheet is saying that this driver can deliver 500Hz or 20kHz information at a usable level. When I equalize a HF horn, I cut the "hump" until the the response is where I want it.