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Old 17th October 2008, 01:18 PM   #1
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Default fe127e bipoles

Hi all,

I had some boxes made to this design. The guy who constructed them did a great job, i installed the drivers last night by simply tinning the lugs and tinning the internal wire and soldering them together.

I have done a few listening test's tonight and feel a bit let down. Now i know they are not "broken in" yet as they have only had a few hours operation, but i feel the vocals are lacking. They seem distant and just.. plain, average, dont present any detail. Suprisingly the bass is pretty darn good.

I have tried them on two different amp's and with two different sources, same results. The guy who constructed them has lined the inside with felt and chamfered around the back of the driver hole, and has also packed the lower chambers with polyester stuffing. How much stuffing is too much? should it be fairly loose or fairly tight? (i know probably greatly subjective )

Anything else you guys could recommend i try to get a better sound from these babys? i will get pics up tomorrow for ya's (although they dont have a finish on them yet)



Thanks for your time!
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Old 17th October 2008, 02:09 PM   #2
rabbitz is offline rabbitz  Australia
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Give them some time as the FE127E takes a while with some reporting 100 hours. Double check your wiring to make sure the polarity is correct on each driver as if they are connected in series, it's easy to get it wrong. Mids are one of the main attributes of this driver and they throw out heaps of detail.

Make sure you have no leaks as if there are leaks they can get boomy which would mask some of the mids. If you are happy with the bass, then I don't think there would be any issues with leaks or polarity.

I didn't think these were a sealed type driver as the EBP is around 140 which quite high for sealed. However, rules are meant to be broken and the EBP is a guideline only.

Others here would have more idea with sealed as I've only use them in a vented design (details at the same site).

You may just have to be patient.
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Old 17th October 2008, 02:13 PM   #3
hm is offline hm  Europe
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Hello,
my solution would be:

Cornet:
bipol double bass horn

Click the image to open in full size.
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Old 17th October 2008, 02:20 PM   #4
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Yeah i have checked the polarity already and they are correct. I have tried them in series and in parallel. Both sound ok. I know i need to get some of that non-hardening sealent and put a small amount around the back of the drivers where they enter the cutout, as to achieve a better seal.

Also one driver seems to be noticably quieter. Even when slightly/lightly touching the rims of the cones to feel there exertion it doesnt go as far/powerful. Could this be a "break in" thing?. I have checked the resistance across each driver and they are all very very close, so it's not out by a major amount or anything.

I will grab some correct lugs tomorrow hopefully if Altronics have some and try that as well incase my soldering was crappier then i thought but it looked pretty good. Bar all that i will play the waiting game.



Cheers!
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Old 17th October 2008, 02:24 PM   #5
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Looks interesting hm!

I had a look on your WWW but couldnt find cornet. Do you have any more information?
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Old 17th October 2008, 02:27 PM   #6
hm is offline hm  Europe
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Hallo,

in german : KORNETT
double horns, scroll down.
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Old 17th October 2008, 02:50 PM   #7
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Before making any drastic decisions, a) make sure the drivers have at least 100 hours on them, and b) loose some of the stuffing. Too much just sucks the life out of the midrange. As they're also lined, you don't need much.
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Old 17th October 2008, 02:52 PM   #8
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Yes i have a feeling there may be too much stuffing in those bottom chambers. Will have a play around tomorrow and see if i can hear any differance.

On a positive note i have noticed beer makes them sound better
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Old 17th October 2008, 05:06 PM   #9
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From what I've read and my own experience with the 127's I'd
do the break in procedure of running 100 hours straight with a radio tuned to an unused frequency (takes about a week or more) and start at zero by using no stuffing whatsoever. The white noise covers all all frequencies unlike doing test tones.

I've learned that you can't assume any given amount of these things is a baseline.

For new builders doing break in, the drivers are put in a container heavily sound proofed and run bolted together face to face, one in phase and one out. You do this at full volume, so the trunck of a car or an old unused refrigerator makes a good sound proof container.


What I did was put them in a box, turn up the amplification source/
receiver and leave for work. Nobody wants to hear that noise while it's going on.

Also with bipoles you did not mention your room or sound setup.

I have to go back and look at the picture yet.
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Old 17th October 2008, 05:07 PM   #10
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I'll repeat it... get at least 100 hrs on them.

You may find that you need to have some polyfluff at the very bottom of the box to minimize the 1/2 wavelength TL resonance.

These will also have a bipole dip just below 650 Hz. You can play with moving that dip down (and decreasing its magnitude), by adding cardboard wings to the sides...

This size sealed FE127 should be rolling off below 100-115 Hz. If you find real bass MIA and don't want to add woofers, the cabinet is about the right height for an ML-TL. (i was actually thinking about getting scott to run a (close to) end loaded ML-TL for these drivers -- fantasies of creating an EPI minitower inspired box)

Driver spread in the FE127s i've measured can be significant. Can you measure impedance?

dave
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