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Old 31st January 2008, 06:48 PM   #1
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Default Got some drivers, now what?

Impulse buying may be the death of me.

Right in the middle of preping for my Half-Chang build, These guys pop up on ebay

http://www.hemptonespeakers.com/Hemptone%20FR%205.pdf

$99 for the pair. I was planning on getting a pair in the distant future but I really liked the price. The problem is what to do with them? They claim to be "Drop ins" for FE127/126, but that doesn't really jive with me. With various spreadsheets(I'm kinda math-lazy) I have lined up a BIB and a 31.5 ltr BR to try. Has anybody used these drivers? Any other designs to suggest? Searches just pull up the FR8 mostly. See this thread for Room and Amp to be used.


Decision 2008

The Half-Changs will still be built. Just I have a swap out project now.

I think I've gotten ahead of myself.
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Old 31st January 2008, 10:12 PM   #2
chrisb is offline chrisb  Canada
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This may be a great sounding driver, and could work very well in or even better in some respects in closures optimized for the FE126 / FE127. However, based on dimensions given on the spec sheet alone, certainly not a "direct drop-in" replacement for them in a strict physical sense.



Both the mounting and cutout diameters are larger than the Fostex, by approx 8mm. While enlarging an existing main cutout wouldn't be a huge issue; if replacing a driver rebated for flush mounting, the pincushion frame pattern would be much more of a challenge, as would magnet bracing if used.

It can get very confusing discussing "hemp cones", as there are at least 2 major players offering drivers to diyers and OEMs. Not only will there likely be varying degrees of sonic differences between respective companies' products, but thanks to the "democracy of the internet", odious politics and innuendo are abundant.

I've heard Hemp Acoustic FR4.5 in both a Fonken and bipole Metronome, and they're more than pleasant.

vis a vis the FE127En? - that's entirely a matter of taste - I personally found the Hemps a bit darker than I like.


The saving grace of many of Scott / Dave's designs is their tolerance for variations in driver's T/S parameters.
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Old 31st January 2008, 10:39 PM   #3
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Thanks Chris

Yeah, I've seen alot of the mud flinging over the various Hemp drivers. I'll have to mind my P's and L's

What constitues a large difference in T/S parameters anyway? A quick look show the published specs of the Hemp Acoustics measurements to be a bit closer to the FE127 while my Tone Tubbys are a bit further off than that.

When all is said and done, I'm guessing I'll try out a few designs. The various fostexs are on my future shopping lists so if the hemps don't work out it won't be a total loss.
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Old 31st January 2008, 11:09 PM   #4
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Quote:
Originally posted by gurley123
When all is said and done, I'm guessing I'll try out a few designs. The various fostexs are on my future shopping lists so if the hemps don't work out it won't be a total loss.
Try modeling them in WinISD alpha. Use the quasi 3rd order vented box option, this should give you a good idea of how they will perform in the bass region.

I'll give the numbers a try later if there is time.

Jeff
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Old 1st February 2008, 01:09 AM   #5
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THe trouble for me is that I only have Mac at home so that takes WinISD out of the picture for me. Is there a free Speaker modling program for Mac? I haven't had much luck finding one.

BTW It's a powerPC Mac so Bootcamp isn't an option either.

P.S. I love my Mac.
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Old 1st February 2008, 02:34 AM   #6
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Quote:
Originally posted by gurley123
A quick look show the published specs of the Hemp Acoustics measurements to be a bit closer to the FE127
Actual measured parameters for the HA 4.5 show it to be midway between the 126 & 127. While factory data for the 127 ends up with a good match with real drivers, i am afraid that using factory data for the 4.5c will not, so i have to fudge a set of working parameters.

dave
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