Home » Audio » Speaker » A little article about a BLH....why go to the trouble.....
Maximum SPL charts [message #21296 is a reply to message #21186] Mon, 12 September 2005 06:02 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18695
Registered: January 2001
Illuminati (33rd Degree)

Here's a chart that will help quantify matters. Below is an SPL chart based on Fostex specs. Add 6dB for π/2 radiation, where applicable. I've included maximum output based on the 10log figure, which of course assumes that X-max is not an issue and that there is no compression. In other words, the maximum SPL listed here is rather optimistic.


[Model][size][SPL at 1W/1M][Max power][Max SPL at 1M][Max SPL at 10 feet][Max SPL at 15 feet]
=============================================================================================
F83E 3" 88dB 10watts 98.00dB 88.25dB 84.75dB
F120A 5" 89dB 30watts 103.75dB 94.00dB 90.50dB
F200A 8" 90dB 80watts 109.00dB 99.25dB 95.75dB
FE87E 3" 89dB 15watts 100.75dB 91.00dB 87.50dB
FE103E 4" 89dB 15watts 100.75dB 91.00dB 87.50dB
FE107E 4" 90dB 15watts 101.75dB 92.00dB 88.50dB
FE108EΣ 4" 90dB 24watts 103.75dB 94.00dB 90.50dB
FE126E 5" 93dB 45watts 109.50dB 99.75dB 96.25dB
FE127E 4.7" 91dB 45watts 107.50dB 97.75dB 94.25dB
FE166E 6" 94dB 65watts 112.15dB 102.40dB 98.90dB
FE167E 6" 94dB 65watts 112.15dB 102.40dB 98.90dB
FE168EΣ 6.5" 94.5dB 80watts 113.50dB 103.75dB 100.25dB
FE206E 8" 96dB 90watts 115.50dB 105.75dB 102.25dB
FE207E 8" 95dB 90watts 114.50dB 104.75dB 101.25dB
FE208EΣ 8" 97dB 120watts 117.75dB 108.00dB 104.50dB
FF125K 4.5" 92dB 50watts 109.00dB 99.25dB 95.75dB
FF165K 6.5" 94dB 70watts 112.50dB 102.75dB 99.25dB
FF225K 8" 96dB 100watts 116.00dB 106.25dB 102.75dB


Re: Horns, transmission lines and reflex cabinets [message #21314 is a reply to message #21206] Mon, 03 October 2005 10:41 Go to previous messageGo to next message
Retsel is currently offline  Retsel
Messages: 23
Registered: May 2009
Chancellor
Here is a recent testamonial which describes the improvement of a Lowther DX4 in a back horn over that of a reflex box.

http://www.audioasylum.com/forums/hug/messages/94352.html

Transmission lines are probably between a reflex box and a backhorn, but still would not have the same quality of sound that a backhorn provides. Again, perhaps the most important benefit of backhorns is that the backhorn allows for a sufficient expansion and low frequency boost that does away with crossover components for these very fine drivers.

Retsel

Re: Horns, transmission lines and reflex cabinets [message #21315 is a reply to message #21314] Mon, 03 October 2005 13:57 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18695
Registered: January 2001
Illuminati (33rd Degree)

Not to be rude, but an impassioned "testimonial" from an anonymous post on Audio Asylum does absolutely nothing for me.


Re: Horns, transmission lines and reflex cabinets [message #21316 is a reply to message #21315] Mon, 03 October 2005 14:41 Go to previous messageGo to next message
Retsel is currently offline  Retsel
Messages: 23
Registered: May 2009
Chancellor
Thanks for your opinion Wayne and it is not rude by any means as we all must carefully consider the claims made by these posts (including this one) before acting on them. Indeed those are words of wisdom to all our readers. Although while I also have found some of these posts to be "blather," I have found that many have some very important information or observations which deserve my consideration. Indeed, some of the best tweaks I have made to my audio system came from such posts.

I did not post this comment for your eddification as your opinions seem so strong that I really did not think that you would change your mind based on this individual post, or even a multitude of such posts. However, for the thousand or so other readers out there who have not made up their minds, this post should help them to consider choosing, or at least listening to, a back horn before they might choose a reflex box or transmission line. They may still choose a reflex box or transmission line for WAF issues or for cost, if they can get a reflex box cheaply on E-bay from one who has upgraded to a backhorn, but they are doing so with the full knowledge of the tradeoffs in musicallity involved.

Retsel

Re: Horns, transmission lines and reflex cabinets [message #21317 is a reply to message #21316] Mon, 03 October 2005 15:15 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18695
Registered: January 2001
Illuminati (33rd Degree)

Don't misunderstand me. I like backhorns. But I also like reflex and transmission lines. They are more similar than different. It's the specific implementations that I'm more interested in, because that gives you something to talk about. Without specifics, you're not able to make comparisons.

Consider a tapered transmission line with its closed end having the same cross-section area as a backloaded horn, its mouth at the same position and area, expansion rate and driver the same. What I am describing to you are two identical boxes, one called a transmission line and the other called a backhorn. Without more specificity, you can't necessarily say there's a difference.

Another example is to compare a 2ft3 transmission line or backloaded horn with a 4" or 6" 90dB 20 watt driver to a 10ft3 reflex box with a 95dB 600 watt flux-stabilized 18" woofer. It's not really a fair comparison, because the scale doesn't match. The reflex box will beat the TL/BLH in terms of efficiency, maximum output, distortion and extension. It won't work as a full range driver, but my point is that without more specificity, the conversation has no reference point and therefore no meaning.

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