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Old 9th July 2007, 03:27 PM   #1
marce is online now marce  United Kingdom
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Default Fe166

I've just finished my Fostex BLH's with FE166's, cabinet is the Fostex design, with some slight mods (thicker sides, rear and baffle) all internal dimensions kept the same.
I am going to add a FT17H and probably a Rythmic Audio subwoofer as time and funds allow.
I have looked round loads of forums as to the running in for the Fostex's, and all say the same, ie requires lots of running in!
What I want to know is what will improve, I seem to have a lack of bass output at the moment, it is there but not as much as I'd expect from other posts, and occasionaly a sort of muddled sound (hard to describe, occasionaly it sound wrong).
I have spent about 15 hours in front of them so far, in the 2 days since I put them in the cabinets, and even in this new state they are absolutely the best speakers I have ever heard, the detail I can hear in the music is incredable, they are beautiful.
They are currently being powered by an Audiolab 8000A, CD player Maranzts CD63.
So I would be grateful if anyonre with more experiance of both Fostex drivers and BLH could give some indication of what to expect during run in.
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Old 9th July 2007, 05:23 PM   #2
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I don't actually think it's break-in (or the lack thereof) that's causing you a lack of low bass so much as your amplifier.

There's nothing wrong per-se with the Audiolab, but it's about the worst possible partner to a low Q driver I can think of offhand. It's got a an extremely low output impedence (high damping factor) which doesn't suit a low Q driver like the FE166E at all. What this means in practice is that the amp isn't doing anything to help compensate for the driver's LF roll-off. What you really need is to swap the amp for something with a lower damping factor. Valve amps are usually a favourite, as they have a low damping factor, but T-amps, Gainclones, and Nelson Pass's Zen & First Watt designs are also very popular. Beware the cheapest T-amp though -it rolls off rapidly below about 60Hz.

In the meantime, there are a couple of things you can do. Firstly, thrash the drivers with Metallica, Iron Maiden, 1812 overture or similar for an hour. That'll loosen the suspension up nicely, and you'll likely have about 95% of the driver performance straight away. As a rule, ears break-in more than drivers do. The rest will come in over the next couple of weeks or so. You'll find a whisker more extension, but an overall slight smoothing of the sound, although the 166 is never going to be a soporific listen, above all on the end of an Audiolab.

Next, junk the speaker cable you're running at present, and use a single pair of twisted 24AWG conductors extracted from a run of Cat5 network cable. The additional series resistance caused by the very thin wire will raise the effective Qe of the driver and also the bass levels (basically this is what a low DF amp does). Alternatively, keep the cable you've got at the moment, but add a small resistor (4-5 ohms should do nicely) in the postitive lead going to the driver. Same sort of thing -I prefer the high-resistance wire route, as the less connections there are the better (I bet connections have caused more problems in history than any piece of wire has ever done). BTW, something to keep in mind is that Fostex drivers do like a few minutes to warm up before they give of their best -I suspect they're designed with that in mind (increased voice-coil resistance etc).

You'll get an overall improvement in the midrange by fitting a pair of phase-plugs: see www.planet10-hifi.com which will remove the resonance at ~3.5KHz by filling in the hollow-pole piece, and clean up the treble. They're a doddle to fit -if I can do it, anyone can. But the first thing you should look to is the amp -it's the main cause of your weak bass.

Hope this helps
Scott
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Old 10th July 2007, 07:52 PM   #3
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Actually, make that a larger resistor, say 3 watts or more, and
try the range of 1 through 5 ohms.

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Old 10th July 2007, 08:00 PM   #4
ronc is offline ronc  United States
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I am not a big fan of fostex design horns, however some do well.
When you design overlapping 1/4,1/2 wave resonators there is more dependance on the TL action which in itself is not a bad thing, however when its TLdependant the action loses the actual defination that real horns are capable of due to the primarly resonance action vrs wave expansion. The first is primarly cab dependant the second is primarly driver/CC/throat dependant.

ron
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Old 10th July 2007, 09:31 PM   #5
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Makes sense to me Nelson -thanks for the correction.

Agreed about some of the Fostex cabinets not being great Ron. The 166 & 206 boxes are not among their finest examples IMO, although the huge hole at ~130Hz should be filled in a bit with the room's vertical mode.
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Old 11th July 2007, 08:45 AM   #6
marce is online now marce  United Kingdom
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Thanks for the advice, I'll be evolving the system and trying things out as I learn, and more importantly can hear differences in the experimentation.
After a couple of late listening sessions, I'd already deceided that the Audiolab and CD player are next on the list for upgrades.
I will be borrowing some valve monoblocks from a friend at work, to try out, what worrys me is that I will like them and then want some, which will mean more grovelling to the missis.
I would like to try the phase plugs, and have read other posts on fitting them !
I havn't thrashed the drivers yet, in fact I've been a bit (!) weedy with the volume control, it hasn't got further than 20 to, as I've been frightened of cooking them.
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Old 11th July 2007, 09:26 AM   #7
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I thought Audiolabs only went up to 11... (sorry )

The 166 will get to high levels with only a couple of watts input, and it's a well-made unit, so you're unlikely to fry them unless you're going insane with the volume-knob. In fact, I suspect you'll be lucky if you can stomach more than about 3-4w going into them. So, crank it to whatever level you find loud, with some decent metal or heavy rock etc, carefully drape chuck an old blanket or similar over them (leaving some air around the drivers) so the neighbours don't come after you with a variety of garden implements, and go and do something else for an hour or so. That should do the trick nicely, as far as running-in is concerned.

The CD player isn't too bad actually -the CD63 was always a nicely musical unit, so you're doing right to look at changing the amps first IMO. If you want valves in the UK, then the World Designs kits: www.world-designs.co.uk are pretty much as good as it gets. Some of the Chinese imports are very good, but it's a lottery about which are and which are not -you won't know until it arrives at your house. The Bottlehead kits from the US are also supposed to be very good, but you'd need a step-down transformer, as well as to pay VAT & Import Duty on them, which takes away their bargin status. Don't rule out SS amps though. Some of the Gainclones & T-amps work well, and Nelson's Zen & First Watt designs are stunning performers for FR drivers -I love the F2 a friend build a while back.
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Old 11th July 2007, 10:41 AM   #8
marce is online now marce  United Kingdom
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I am thinking of a gainclone type as an electronics project as we us the 1875 in some test equipment at work, and it seems an easy and relatively cheap way of starting to play with amps and electronics. I also want to add some FT17's and a nice project would be gainclone amps and active crossovers on the same board, I could then play about with crossover values etc.
What true horn designs are there for the FE166, FE206 though if I start building new cabinets, I may end up rather poorly, as I promised my beloved some fitted bedroom furniture (before the speaker building bug got me).
Thanks for the ideas, certinaly gonna thrash them for an hour and dig out some high wattage resitors.
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Old 11th July 2007, 11:34 AM   #9
Puffin is offline Puffin  United Kingdom
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Marce. If you want to try a cheap Class D amp. Have a look at the thread in Class D " Best value T-Amp in the U.K" and have a look at what is available and the simple mods required. I am just running mine in, having modded several Sonic Impacts and I have other commercial Class D amps to compare it with. I think it is excellent for 20 plus a few resistors and replacement caps.

I use mine with Fostex 206E's in a 208 BLH cabinet, Superb.
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Old 12th July 2007, 10:19 AM   #10
marce is online now marce  United Kingdom
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Tried some resistors last night, definetly get more extension, but more imoportantly found them less fatiguing to listen to and could turn the volume up more. Uses a 2R2 resistor, and am going to try CAT5 cable, 5m per side gives me approx 2R loop resistance.
Will go for the phase plus at end of the month - slowly building up courage to hack! the drive units with a scalpel.
God news, I'm borrowing some EL34 mono blocks to play with so I can compare with solid state, plus the Guy who's lending me them wants to know what they sound like through horns.
Bad new is the Marantz went clank instead of clunk, so I'm using a oldish kenwood CD player.
So thanks for trhe advice Scottmoose, the sound is much more enjoyable.
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