4 ohm or 8 ohm better for SPL from panasonic receiver ? - diyAudio
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Old 30th September 2009, 10:57 PM   #1
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Default 4 ohm or 8 ohm better for SPL from panasonic receiver ?

i have a 100wpc panasonic sa-xr receiver that i want to use for light duty DJ work. i want to move as much air as i can cleanly. would you say i should build 4 x 8 ohm or 4 x 4 ohm high power mid towers? i've never heard of anyone driving a panasonic hard at 4 times 4 ohms yet, but it seems that other class D amps like 4 ohm loads. i actually bought it originally for a 4 ohm stereo magnepan system i never completed.

i want a rig that's as high quality sounding as possible that's reliable. if i could do a 4 ohm system, i'd like to use 94dB Bohlender Graebener planars 2 or 3 way.

my understanding of class D is that it slowly starts to distort instead of clipping. i don't intend to push SPL into audible distortion at all. i've managed to get some respectable SPL in 8 ohm stereo with 5 1/2" & 1" @ 86dB minimonitors already, but would like to build a 4 ohm @ 94dB with 4x 5 1/4" midbass.

to me, it sounds better than a similar 91dB 8 ohm system even if it's a harder load on the amp the 3 extra dB would negate any difference with a few extra watts i imagine?

while we're on the subject, here's another question i never had answered in another forum... what would you say is the minimum gauge wire i should use for up to 50 foot runs at up to 100 watts? 16 gauge?

any help with these tech questions is appreciated

Last edited by budget minded; 30th September 2009 at 11:03 PM.
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Old 30th September 2009, 11:06 PM   #2
Glowbug is offline Glowbug  United States
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Little app that's handy for sizing speaker wire: http://www.bcae1.com/images/swfs/spe...rassistant.swf

I'd probably use 14awg, but that's just me.

I don't know if your receiver will be happy in this kind of role, there are rack mount amps better suited for use and abuse at low impedances and under the conditions you'll face in even light-duty DJ work. Something like a used Crown or QSC RMX or Powerlight would be my choice...
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Old 30th October 2009, 07:12 PM   #3
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thanks for the 14 gauge recommendation. if i make any money, i'd go to 10 gauge oxygen free. i plan on a system that puts a speaker in each corner of a 20' X 20' max dance floor with the 4 LED projectors i already have sitting on top of each speaker pointing down on the crowd, unless a client prefers ceilings or walls & i've considered sheet fabric for rear projection outdoors.

there are a DOZEN reasons i want to use the panasonic,
1. i already have it
2. i'm on a tight budget & have 4x satellites & subs to build, plus wiring, plus speaker stands, plus EL wire lighting for the stands
3. might not get any gigs as DJs only play evil gangsta & techno out here & i will ONLY play funky & upbeat
4. i have lower back issues and don't want heavy gear. if it weren't for the weight, i already have a pair of 200+wpc power acoustik car amps with cool plasmaspere (lightning) displays that pulse to the music i could use
5. i love the fast sound of class D (especially in the midrange) and will never go back to muddled A/B again... clinical sound works for me as long as it isn't harsh & my panasonic is effortless to my ears. it beats the daylights out of my former NAD except in bass output maybe, but i'll be using it for satellites in "small mode" anyways
6. until i start getting paid (NOT my motive for DJing to begin with) i can't justify wasting a couple thousand dollars in gear
7. i don't have a car, so i'll need to be able to fit everything in a rented pickup truck/driver in one trip
8. it pushed my tiny little 86dB mission M71 5 1/4" 2 ways very loud without distorting at all to the point they started sounding like subwoofers
9. i'm a tree hugger, so class D efficiency is a best friend. i DO have my eyes on $300 300wpc class D rack amps though if i could justify the expense
10. before upgrading amps, i want to ditch my gemini starter kit for better denon gear. THAT'S my first upgrade
11. i want a behringer DEQ to tune my system's EQ to flat for each venues acoustics, unless a client wants extra bass
12. i'm looking to do smaller house parties & "high end" adult parties not 120dB hearing destroying concerts

i don't want to compromise sound quality one bit (including music). i'm looking to fill a VERY specific niche and have come up with the motto

the easy on your ears DJ

my panasonic fits so many of my priorities selling out to inferior sounding PA gear is an abomination to me. i hate "club sound" from the sloppy oversized ported subs to the ear splitting screechy horn tweeters. louder at the expense of sound quality is annoying to me.

i guess i'll just build 8 ohm speakers then. it's just i've read that at least some smaller class D amps PREFER 4 ohm loads. regardless of what speakers i run, i won't push SPL into any sort of distortion.

Last edited by budget minded; 30th October 2009 at 07:22 PM.
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Old 3rd November 2009, 09:51 AM   #4
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i think i'll be getting 16 X Vifa BC18SG59-08 6-1/2" woofers at 89dB & 80w power handling for 4 X 8 ohm satellites at 95dB efficiency. that will make for speakers much bigger and heavier than i want to deal with, but i'll have power handling & efficiency comparable to evil sounding PA speakers with their sloppy bass & shrill treble.

now i just have to figure out what i'm going to do for tweeters. i originally wanted dayton (MB quart) titanium tweeters that are rated at 50w & 93dB, but now i think i'll stack 4 X goldwood (audax style) polymer tweeters & pad them down for better power handling, to match the SPL better (the dayton's are only 93dB at peak), a mini line array will give better dispersion and because it won't be much more expensive than the daytons even if i bet i'll lose a little SQ.

i'd really like to use ribbon tweeters, but at $300 a pop for ones that can cross over low enough & handle high SPL, that's not realistic and open fabric domes are out of the question as the world is full of tweeter poking fidiots, and i'm sure alcohol doesn't discourage that noise one bit.

building high efficiency satellites isn't easy. if you find an affordable woofer that has high efficiency, it has lousy power handling and vice versus unless you want to buy $100+ morels or dynaudios. getting the right impedence is an issue too, and then when you want to find a matching tweeter, good luck on that.

i'll just have to accept building speakers bigger, more expensive & fuglier than i wanted to keep sound quality (mostly) uncompromised.
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Old 3rd November 2009, 10:44 AM   #5
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As you've found out, smaller boxes mean bigger wallets for the same sound. Good luck with the project. I also do a little bit of djing and stick rigidly to providing a quality sound and all my kit is diy, I've had one girl come up to me asking how do I get such good sound from those "old" vinyl records
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Old 3rd November 2009, 02:20 PM   #6
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Quote:
Originally Posted by budget minded View Post
i think i'll be getting 16 X Vifa BC18SG59-08 6-1/2" woofers at 89dB & 80w power handling for 4 X 8 ohm satellites at 95dB efficiency. that will make for speakers much bigger and heavier than i want to deal with, but i'll have power handling & efficiency comparable to evil sounding PA speakers with their sloppy bass & shrill treble.

now i just have to figure out what i'm going to do for tweeters. i originally wanted dayton (MB quart) titanium tweeters that are rated at 50w & 93dB, but now i think i'll stack 4 X goldwood (audax style) polymer tweeters & pad them down for better power handling, to match the SPL better (the dayton's are only 93dB at peak), a mini line array will give better dispersion and because it won't be much more expensive than the daytons even if i bet i'll lose a little SQ.

i'd really like to use ribbon tweeters, but at $300 a pop for ones that can cross over low enough & handle high SPL, that's not realistic and open fabric domes are out of the question as the world is full of tweeter poking fidiots, and i'm sure alcohol doesn't discourage that noise one bit.

building high efficiency satellites isn't easy. if you find an affordable woofer that has high efficiency, it has lousy power handling and vice versus unless you want to buy $100+ morels or dynaudios. getting the right impedence is an issue too, and then when you want to find a matching tweeter, good luck on that.

i'll just have to accept building speakers bigger, more expensive & fuglier than i wanted to keep sound quality (mostly) uncompromised.
High efficiency does not have to mean sloppy bass or shrill treble. You're more likely to get that from overdriving components meant for living rooms. *IMO*, you need to look at moderately priced, high efficiency pro-audio woofers and horn (or waveguide) loaded compression tweeters. You should be able to get efficiencies in the 95+ dB range and good clean sound without spending fortunes, you just have to choose wisely and be realistic about how loud and how low you need them to play.

My home theater system uses a Panny SA-XR55. The current main speakers use a $69 P. Audio 12" woofer (E12-200S). It's good for 95 - 96 dB/W, and as I have them loaded they should be able to play at 110 dB from 40 Hz up. The top end uses a $9 JBL waveguide with a $40 Selenium compression driver, and the crossover described at AK Design Collaborative - Econo-Waveguide Speaker - AudioKarma.org Home Audio Stereo Discussion Forums. The top end is well sorted, and sounds good for domestic use, let alone PA. Pick a woofer that will do what you need and go from there.

For more inspiration, look at Wayne Parham's Pi speakers. Pi Speakers - unmatched quality and state-of-the-art performance. The 3 Pi or 4 Pi are right up your alley. They are used both for domestic and PA use, and should suit your needs better than a stack of fragile dome tweeters.

Again, it's all IMO...

Bill
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