|Multi-Way Conventional loudspeakers with crossovers|
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|20th June 2012, 10:19 PM||#1|
Join Date: Jun 2012
New guy doing budget 2-ways w/ $9 PE Aura 6"s & horns. Constructive criticism sought
This is my first post on the forum ... I'm in the planning stages of building myself some new speakers for my home theater, what I currently have are pretty pathetic, especially compared to the rest of my equipment has been updated/upgraded EXCEPT my speakers over the years. Luckily, I got to look like good husband when my wife wanted to get her Dad a surround sound receiver for Father's Day, I told her she could just put all the money towards the receiver, he could have my old speakers, and I would go ahead and do my new ones .
Honestly, I'm not interested in using an preexisting design, I would much rather do all the design and construction work myself. I have an EE background, I was laid off after 5 years as an RF network design engineer for a wireless co., decided to go back to school and turn my 2-year degree into a 4-year... Just last semester I took another linear circuitry class that may-as-well have been called crossovers and filters 101, so I am comfortable with the filter design portion of the project (not to mention I have X-Over Pro 3 and Multisim 11.0). Since I'm on summer break, a nice little electronics project would be nice.
The setup will be a 7.1 surround (first time, always used 5.1 in the past, but I have a 7.1 receiver and may as well use those other 2 channels), medium-sized room. I have a Harman receiver that outputs 55WPC to work with. I'm not expecting perfection or speakers that sound like they cost thousands and thousands, just some very good sounding speakers. I don't want to get too fancy my first time out since I'm not familiar with all the esoteric little details to speaker design. I was planning on using 2-way designs all the way around. I'm on a fairly tight budget to put my speakers together, so I was going to take advantage of some good deals at PE on the drivers, plus I can leave enough $$$ so I don't have to skimp on my filter networks and component quality. With only 55WPC to play with, I wanted to design something that would have fairly high sensitivity, even though it's not a HUGE room, I like volume, A LOT.
The one speaker that I will be keeping is my LFE channel; it is a pair of Image Dynamics IDQ12v2 12" subs (automotive; I know a lot of people don't like car speakers in HT, but they sound great) in a 7ft^3 vented box tuned to 25Hz, powered by a Peavey PV500 PA amplifier (500W into the 4 ohm load). Needless to say, I have plenty of good, clean subbass.
The foundation of all the speakers will be the $9 Aura NS6-255-8A 6" from Parts Express. It seems like a really decent driver if the simulations I've ran in WinISD and Bassbox Pro 6 are accurate, especially for the price. Since they're an 8 ohm speaker, for the left, right, and center speakers, I plan on using 4 drivers per speaker so the receiver sees a 8 ohm nominal impedance, at 91dB @ 1W/1m, 4 of them should get me 97dB sensitivity, at 55W I would certainly think it'd achieve my SPL goal. I haven't seen any budget-priced single dome tweeter that with a sensitivity greater than 94dB (Vifa makes some budget-conscious tweeters with that sensitivity), so to keep up with the 4 Auras, I planned on running horn drivers coupled with L-pads. The tweeters are costing me much more than what I intended on spending (a whooping $50 each), but I want something that sounds good, can be crossed over low since with the 2-way I'm omitting a midrange (not sure of a point yet, haven't played around with it much), and can keep up with the 97dB sensitivity of my woofers. I was planning on using a Selenium DH200E-E 1" titanium driver coupled with the Selenium HC23-25 horn, with a minimum frequency of 600Hz, a 100 degree horizontal and 40 degree vertical beamwidth (the propagation of those horns will work really great in the room based on the seating and equipment positions) .
For my main speakers, I need the cabinets to be more similar to the large 60's & 70's because of space requirements, I was going to arrange them in a 2x2 pattern (with the horn above) in a vented enclosure, 2.75-3.25ft^3 tuned to 50Hz. For the center speaker, again because of space requirements, they'll need to be in a 1x4 configuration horizontally (with the horn below, the center channel is in a bridge above the TV so below the woofers puts the tweeter closer to the TV), in a vented enclosure 2.75-3.0ft^3 tuned to 50Hz.
The surrounds are gonna be really basic and ultra cheap; just one of the Auras in a .5ft^3 sealed enclosure with a Nuance TW5-120LR 1/2" mylar tweeter, $2.50 at PE. Hell,l I may even just use a 1st order XO to make them REALLY cheap (probably not, probably stick with 12dB/octave, but can't say for sure until I see the total). This tweeter's sensitivity is also 91dB at 1W, so it matches the Aura exactly.
I guess what I'm looking for are critiques of my setup... What do you think? For the centers and main, I was using a ported enclosure to help with the bass output, would there be any advantages to a sealed enclosure? What about the horns, I really don't want to be disappointed in them considering how much I have to spend on 'em, obviously their volume won't be an issue, I will admit I'm concerned about their SQ, but they seem to have excellent reviews on PE. I had a fleeting consideration of using a 2.5-way setup instead of a basic 2-way, would I noticeable improvements with a 2.5 (obviously it wouldn't work for my proposed 2x2 config for the mains, but it would for the center). I was sorta thinking about using a LR2 at 2kHz, Bassbox says the Auras in the vented enclosures I mentioned would only be down 2.2dB from moved up to 3kHz the woofers would be down -4.4dB, but some reviews on PE mentioned that they had better SQ. Before I found the Aura, I was planning on using the equally cheap Focal 6M115, but it seems to roll off much, much more above 750Hz and doesn't have the the bass output. Any opinions on the Aura vs. the Focal? For the horn driver, I was also considering the Eminence ASD1001, it's $10 cheaper but has equally good reveiews, but I don't know much about either.
Last edited by nosaj122081; 20th June 2012 at 10:40 PM.
|21st June 2012, 12:29 AM||#3|
Join Date: Nov 2003
Location: Brighton UK
i have an EE background but i know my acoustics as well, without which
you are totally lost, e.g. the Nuance with a single capacitor gives a classic
near Butterworth 3rd order acoustic roll-off.
All the EE courses I've ever done don't teach you about audio, and
encourage a very blinkered attitude that its far simpler that it is.
Anyway checkout Speaker Design Works and madisound.com for a
two designs and three kits related to the very good value Aura driver.
http://sites.google.com/site/undefinition/diy (see if nothing else, the excellent FAQs)
The Speaker Building Bible
Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
FRD Consortium tools guide
Designing Crossovers with Software Only
RJB Audio Projects
Jay's DIY Loudspeaker Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
A Speaker project
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design
Great free SPICE Emulator : SPICE-Based Analog Simulation Program - TINA-TI - TI Tool Folder
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
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