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Old 25th December 2008, 01:26 PM   #11
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labougie,

I don’t know if you read my previous reply, but I have plenty of real world experience with the Eminence 8”.

You should have no problem with distortion being overly audible with the detuned guitar hitting 70 HZ.

I have even played bass guitar through Alpha 8s, and it sounds OK on the low E, though the response drops like a rock below 60 HZ.

The suspension is pretty stiff, you have to hammer them pretty hard to get nasty sounds out of them.

With a steep HP filter at 60 or 65 HZ you will be just fine.
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Old 25th December 2008, 01:59 PM   #12
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Thanks for that weltersys. How do you get on with a crossover when you're running the two 8s in series - can you buy one with a 16 ohm LF and an 8 ohm HF?
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Old 25th December 2008, 08:15 PM   #13
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labougie,

I designed my own crossovers. I am not 100% happy with them, and will be doing a redesign coming up pretty soon, which will be considerably easier now that I have the SMAART program, and will be able to see the response accurately as I change the values of the capacitors and inductors.

I am running four monitor mixes, otherwise I would actively cross the speakers.

It is so much easier to “dial in” a proper response with DSP than get passive components to play well, and you could still use just one amp to drive a pair of speakers. Sounds like you must have some DSP since you were already talking about the 36 DB per octave HP filter.
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Old 25th December 2008, 08:42 PM   #14
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For the 36db HP, I was going to build ESP's rumble filter and put it and its psu into a box between mixer and amp.

Quote:
Originally posted by weltersys
.......and you could still use just one amp to drive a pair of speakers.
I think I'm being dense here - how can I use an active crossover with just one amp? The crossover is at line level, no?
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Old 25th December 2008, 08:48 PM   #15
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If you are using a mono amp, not possible, sorry.

A stereo amp, side A for lows, side B for highs.

If you want to run stereo mains, two amps would be needed, but a single space amp with 100 watts per channel would be plenty for the APT tweeters.
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Old 25th December 2008, 08:54 PM   #16
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With the price of DSP as low as it is, a used unit may be cheaper than building a device that only is a low cut.
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Old 25th December 2008, 08:55 PM   #17
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Roger that, I see what you're saying. Goes away to have a muse..........
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Old 30th December 2008, 10:21 PM   #18
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Quote:
Originally posted by labougie
[B]My current PA is a tri-amped affair, 300w mono into one 12” Celestion 1225e (300w) per side, crossed over at 250hz into 2 x Eminence Alpha 6s per side with a piezo, poled up above the 12s and driven by 75w a side. This will run at much higher volumes than we would ever use and is also big and cumbersome. I’m 60 and humping gear about has lost any charm it might have ever have had!
Well, IMHO, it's almost as small as it can get - now you have two relatevly light 12" bass cabs (12" is VERY compact for a bass cab), that you don't have to lift up to poles; and small double-6,5" + piezo cabs that weight next to nothing and can be lifted up with one hand.

I have very similar micro-PA - single Alpha 6 plus piezo in a small, 34x21x18 cm 16 mm MDF boxes and double-8"-inch bass cabs made of 18 mm ply. Crosseover is passive at ~250 Hz. Amp is 2x200 W. All one-man lift, and I'm not the strongest guy in town. A 12" or 15" + comp cab will weight about as much as your current 12" plus 6,5" cab (if not using neo drivers), and you'll have to get them ~1,2 meters up on poles. A double-8" + comp box MAY be lighter, but may be not (my double-8"s are approx. 15 kg each, the lightest not neo and not plastic cabs 12" and 15" are a around 20 kg AFAIK).

If you want to save weight, get some lightweight amps, e.g. QSC PRX series, or Powersoft, if you've got the money 20 kg vs. 10 kg is a big difference. Maybe replace current 12" w/ some neo drivers, e.g. Eminence DELTALITE-II 2512 (2,3 kg - Alpha 6 is 1,9 kg)*, maybe even build new boxes from 15 mm ply for them (60 L and 45 Hz tuning is OK and very compact), and 12mm ply boxes for Alphas (make them just big enough to fit drivers and stuff well with damping), to further save weight. That would make around 15 kg or even less for bass cabs (that will stay on floor) and 7...8 kg for midtops (that actually go up to poles). This way you also will not need to worry about bass extension at all, you could even play some heavy rock or modern dance music through it!.

Also, consider making the mid-tops singles - for acoustical music and 50 people one Alpha 6 would suffice (it suffices for my synths in a typical pub-sized environment, giving around 114 dB at one meter - that is LOUD, esp. in midrange where our hearing is most sensitive), and weight will be around 4 kg per speaker. You can use 2 cabs per side if needed. Remember, hauling around several pieces of small weights is better than one piece of big weight. That's one of the reasons why double-15" boxes are not as popular these days amongst mobile guys. And that's one reason why I don't like active speakers. But that's another story, really...

*On a side note, Deltalite series is not very good for midrange use, having that typical Eminence rising response above 1 kHz. This is not the case with Alpha 6, Beta 8, Delta pro 12 and some others, which are excellent for midrange.
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Old 31st December 2008, 03:10 AM   #19
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Default Small pub PA

First post, long time lurker, long time forum member elsewhere.

I've been doing small pub gigs for 25 years, and evolved my "small system" to use B&C Neo 12" coaxial drivers for both FOH and monitors(foldback in the UK). Even using 18mm Baltic Birch plywood for the cabinetry, I doubt the design is over 30lbs. I have stand mounts installed, and regularly use them on top of Ultimate brand speaker stands.
With an acoustic guitar and male voice as the lowest instruments, this driver should be quite suitable.
For my use, I have them set up as an active(Protea 4.24C processor)system, biamped with QSC PLX2 amplifiers. I'd think the 1104/1804 models would be nice, and very lightweight. I've also done a SMAART analysis on them to help with processor settings and highly recommend this.

I would avoid using the 8" diameter coaxials unless coupled with a 12 or 15" woofer. There just won't be enough full range output. There are times where the 12" Coaxials won't cut it either, but most of the time I've got a five piece Irish group with a very low bodhran, and keyboards and synth. I've used them many times on duos like yourselves with great success.

These drivers aren't cheap, about $400.00 USD. Beyma, Ciare, and BMS all make similar versions, along with Eminence.

This is all precluded by the need for a woodworking shop and talent to build them.

Best regards,

John

PS. From another thread about Tom Danley's designs, I'd prefer not to be regarded as a "minion", although I've been called worse. ;>)
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Old 31st December 2008, 06:31 AM   #20
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If you want really clean sound you probably want to keep cone excursion below 5mm, regardless of the driver capability.
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