Glenn Williams wrote on Sun, 01 November 2009 17:26 |
How is it suitable?
It was designed for the application. It is an E-horn retrofit.
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Did you look at the cabinet in question? It is a Cerwin Vega copy. Cerwin Vega does not make any drivers aimed for horns using a QTS of 0.37
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A review on the website at Parts Express concurs with the more than 30 applications that I have used this woofer in. That review from 2007 was posted several years after I had been using them.
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Parts Express is aimed towards Home Audio & Car Audio enthusiasts. It is not a place where I would class the best source to research on bass horns in Pro Audio.
Speakersplans.com is aimed for DIY horn designers in Pro Audio. PSW Subwoofer Forum is aimed to wards the Lab Sub. I’ll even say the High Efficiency forum on Audio Asylum is a good resource.
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The B-52 information is eronoeous like most of the other information that they publish. I is all extremely suspect. Succinctly worded it is BS.
Their marketing misquotes driver specification among other things. How convenient for them.
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Pretty much like Selenium stating 1600 watts and having a voice coil winding depth of 22 mm, and an xmax of 5.25 mm. The Selenium driver you recommended has the specs of a driver designed in the 1980’s. It will not handle 1600 watts much less 1000 watts.
Did you happen to look at the AES rating? It says 600 watts.
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In the Matrix 2000 when the sub woofer was blown by an aquaintence and removed it turned out to be 600 rms version rather than the 1000 watt version of the Celestion Woofer that B-52 marketing said that it was. hmmmmmm.....
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Was it the driver pictured on their website? How did you confirm the driver was 600 watts? Why would B-52 put a Celestion woofer in their cabinets when, B-52 have been using Eminence for the past 10 years? How do you know it was the original driver?
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They also embellish product by quoting one of their active/passive slave sub products as a system and not an individual box and were slippery enough to say that it was the sensitivity of "the system". System means both boxes instead of a single box. Since most ppl assume that this specification is quoted on a per cabinet basis it is very misleading.
The actual SPL sensitivity figure will be as much as 6 db lower if they are quoting the additional amplification.
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Do you have any graphs to back up this claim? We are talking about folded horns where it is standard to use blocks of four minimum.
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A 220 oz magnet structure ceramic slice in that diameter of magnet structure would require two ceramic slices sandwiched. The entire magnet "structure" including the metal casting might weigh 220 oz, but the actual magnet will be more like 109-120 oz. Both those magnet weights are commomn in the industry. Stucture is another slippery marketing term used along with magnetin the automotive car woofer industry to mislead ppl into believing that it si bigger than it is, so I am quite familar with it.
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The Selenium FH 18W FH1P magnet from the manufacture states 120 ounces. The Eminence OEM magnet states 220 ounces from B –52’s website. That is documented for all to see. Where is your documented proof that the Eminence OEM magnet weight is indeed 109 – 120 ounces as you stated?
Everything I stated in regards to the Selenium FH 18W FH1P is documented in their PDF specifications. Where are the documents in regards to what you stated above so, I can read for myself?
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Furthermore,you make the assumption that the classic so called "E-Horn" is infact a horn.
I will grant you that in a true folded horn, the compression chamber and throat specifcations were optimized for one woofer, and another woofer will not function approprately. It is not wise to implement another woofer in an application designed as a system if one wants the system to perform optimumly.
However, E-horns are not folded horns at all. They may have a compression chamber, but the throat is a flared transmission line like passage, calculated at a given length in order to cordinate in a large port if you will which is also often mistaken for the horn mouth of a Folded Horn.
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Surely you are joking right?
Are saying that one B-52 is going to offer the same low frequency extension as block of 4 – 8 cabinets?
The B-52 copy is a Cerwin Vega design that stretches back to the 1970’s. Please tell me which model number Cerwin Vega offered that matches the TS Parameters in the QTS as the Selenium 18W FH 1P?
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They are very forgiving in variances of most TS parameters and are not optimized like folded horns. They still require High Bl factors. If you had ever been inside the Earthquake or the Jr Earthquake you would have seen that the configuration is NOT a Folded Horn at all. Far from it.
An E-horn is essentially a derivation of a Voight Pipe.
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No folded horn is very forgiving on the incorrect driver. I don’t think you are familiar bass horns as you assume.
Why don’t you post some frequency and excursion charts of the Selenium 18W FH-1P in the box in question?
As a matter of fact, since you are so familiar with the raw drivers of the Eminence OEM used in the B-52 Folded Horn, why not post some charts of the stock driver as well so we can see why the Eminence OEM designed specifically for that box will offer an inferior response to the Selenium 18 W FH – 1P
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Bill Wood's Yorkville LS1208 and LS808 used a futher derivation and tuned the flared port to to the front loading. Bill called this design a Dual Tuned Resonator. Yorkville marketing called it a Bass Pipe. A bass pipe is the generic term for Paul Voight's bass pipe, which in it's purest form is more of a transmission line that opens into a large a port.
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The B-52 (Cerwin Vega copy) is not the Yorkville LS 1208 & 808 that is designed to be used singular. The B-52 (Cerwin Vega copy) needs to be in blocks of 4 to take advantage of the coupling of the horn’s mouth (SPL) and, achieve low frequency extension.
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Yes the Selenium mentioned is eminantly suitable for use in bass pipes, just as certain woofers work well in bass reflex boxes at a given tuning and certain woofers do not. Selenium knew that the E-horn was not a Folded Horn and the design reflects that. The majority of ppl in audio are not even aware of what a Voight Pipe is.
BTW: The technology is just as old as Folded Horns
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I’m pretty sure anyone who is familiar with horns is familiar with the Voigt horn.
However, the B-52 (Cerwin Vega copy) is not a Voigt horn. I don’t know why you would compare the B-52 (Cerwin Vega copy) to Yorkville when the designs are not the same.
Cerwin Vega
Voigt Horn
There are no characteristics amongst these two designs, hence comparing the two is like apple to oranges.
Don’t forget to post some frequency/excursion charts of the Selenium 18W FH 1P in the B-52 (Cerwin Vega copy) so we can see why it is a superior driver over the OEM Eminence driver designed to work on the B-52 (Cerwin Vega copy) cabinet.
Best Regards,