Design Direction for new Home theater setup - diyAudio
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Old 4th February 2007, 03:07 PM   #1
JerMu is offline JerMu  United States
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Default Design Direction for new Home theater setup

First off, I want to preface this thread with the point that I am a noob when it comes to speaker building. I have been casually educating myself on the topic the last 3 or so years. I have built my own sub for my system (Atlas 12) and being throughly pleased with it I am hoping to step into the realm of building an entire set up.

That said:

I am in the preliminary stage of upgrading my entire sound system. I am curious about the type of set up I should go for. Ulitimately I am looking for a system that is very capable when it comes to sound reproduction (nice bass when needed/wanted, but very balanced when an assortment of sounds are being played). I am not what I would consider an audiophile where I want every aspect of the sound, even the stuff that most people can't hear, replicated. I am just looking for the best sound for my money.

Right now I am thinking of two different setups:

A loudspeaker design (3 way full range) with a center channel (2 way), and two satelites(2 way) in the rear, with a sub to handle the bass in 5.1 applications.

-OR-

A design where I have 5 identical speakers (2 way design) that handle mids and highs with two separate subs on either side of the system for bass.

I am looking at the vifa XT25 for the tweeters, and Ascendant Audio's (AA) Assassin for Bass, and AA's 6.5 midwoofer for mid's.

My question is what are the pro's and con's (if any) of doing a loudspeaker setup with satelites versus 5 identical speakers (mid's and highs) throughout with external subs? Does it matter as long as speakers match properly, or does one setup actually perform better? It seems to me that the loudspeaker design could be redundant when it comes to bass, or is that actually better because it takes more in the lower octaves to push the same sound levels as the higher octaves so that it sounds balanced?

Just curious about the boards thoughts, and I am not sold on just these two options if you guys have better suggestions please advise me.

Thanks!
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Old 4th February 2007, 03:17 PM   #2
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Not to throw cold water on your idea but ... I have built speakers in the past and I can tell you that its a lot harder than just purchasing the drivers and picking out a crossover from a book. In other words it gets time consuming and can get very costly.

My personal favorite theatre system would be a JBL Synthesis because it has speakers engineered for the specific purpose. JBL processing and eqing are a vital part of the system.

My personal theatre is comprised of 3 Klipsch Heresy speakers for Right, Left, Center, and Sonance inwalls for the rear surround. With the lack of a sizable amount of money I had to make due with what I could put together. I like the center being the same as the R&L in my system.
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Old 5th February 2007, 05:00 AM   #3
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Quote:
Originally posted by burnedfingers
Not to throw cold water on your idea but ... I have built speakers in the past and I can tell you that its a lot harder than just purchasing the drivers and picking out a crossover from a book. In other words it gets time consuming and can get very costly.

My personal favorite theatre system would be a JBL Synthesis because it has speakers engineered for the specific purpose. JBL processing and eqing are a vital part of the system.

My personal theatre is comprised of 3 Klipsch Heresy speakers for Right, Left, Center, and Sonance inwalls for the rear surround. With the lack of a sizable amount of money I had to make due with what I could put together. I like the center being the same as the R&L in my system.
I think many members here have the bad habit of telling those "don't do your own design it is too difficult". Everyone has to start somewhere, and as long as burned fingers realises that investment in some measurement equipment would be a very smart move then he can't go too far wrong as long as he is careful in the selection of his drivers.

I agree with burned fingers. The center channel should be identical in design and orientation (ie three vertical bookshelves) to the front pair. I also believe it is important to determine before hand how much output capability you want (especially from your fronts as they are often further away). Then determine if a simple TM will suffice, or if the additional power handling and sensitivity of a multiple woofer design would be useful.

To answer your question in short, I'd go for 3 identical fronts, plus two subs. I believe the surrounds are less important, and a skewing of the budget towards the fronts will give better results in the end.
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Old 5th February 2007, 06:37 AM   #4
JerMu is offline JerMu  United States
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I understand it is more than just purchasing the drivers. I however was just curious as to the overall set up and generally how the sound..well for lack of a better way to say it "sounds".

I have played with WinISD a bit for the speakers I mentioned and they seem like a decent combo, that said I am a noob and i know there are a lot of things that go into designing speakers and I might be over looking some factors. That is why I am here.

I just want some overall guidance to whether or not one way might be better than another or if it even matters. Some design tips would be appeciated too. If more info is required about my general design (box size, crossovers, etc..) then I can provide that I just don't want to put too much in this thread if it is not necessary.

On a side note is WinISD capable of demonstrating driver/box relationships outside of a sub? If it is not then I really should go back to square 1. I don't want to get overly complicated, as I noted I am not an audiophile and I know some specs are just a little too precise to be worth the time/money needed to achieve them. I just want a good balance of money/performance. I would like for the money spent to out perform the same price point speakers at my local audio store.
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Old 5th February 2007, 08:41 AM   #5
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You can adjust the frequency range on the X-axis within WinISD if you're wanting to use it to design a midrange enclosure for example, just right click on the graph area and then click on options.

If this is your first project I'd suggest building a well established design first then you have a reference to change components values ect if you want to see what does what. Alternitavely you could find a published design that fits your requirements, buy the drivers and develop your own crossover for them. That way you know you've got drivers that work well togeather and if you can't get your design to sound how you like it for whatever reason you could always build the origonal published design

As for what to build, for a first project you should stick to a 2-way design really, a 3-way is much harder to get working than a 2-way as changing one crossover effects the other ect. If you send all the bass to a sub you can use much smaller, simpler and cheaper main speakers than if you tried to get your front three to go all the way down.

Have a look at the 2 way bookshelf projects on ZaphAudio and Troels Gravesen's site. Depending on how loud you want to go the 5 inch 2-ways should be fine if you're sending everything <80Hz to your sub/s. As already suggested you should really look to build all three fronts the same, surrounds are less important but if you build them the same as the fronts you might get a discount on the drivers depending on where you buy them from
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Old 5th February 2007, 11:13 PM   #6
JerMu is offline JerMu  United States
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Wow thanks for the responses.

Quote:
You can adjust the frequency range on the X-axis within WinISD if you're wanting to use it to design a midrange enclosure for example, just right click on the graph area and then click on options.
Any reason you can't go further and put in a tweeter's info and plot it on the graph too?

Quote:
If this is your first project I'd suggest building a well established design first then you have a reference to change components values ect if you want to see what does what. Alternitavely you could find a published design that fits your requirements, buy the drivers and develop your own crossover for them. That way you know you've got drivers that work well togeather and if you can't get your design to sound how you like it for whatever reason you could always build the origonal published design
I've been looking at alot of the d.i.y's projects already done, especially the showcase on Parts Express's website and my overall design is based off a number of those projects. The only difference is I'm not necessarily going to use all PE parts. I have really enjoyed my Ascendant Audio Atlas 12, and I've been considering trying the Assassin line especially since Chad has mentioned that they are upgrading all their sub's again. The assassin as is was already an upgrade from the Atlas and now "should" be even better. There is a midrange 6.5 speaker he has on the Ascendant Audio website that looks pretty decent. I have not heard it yet, but in the spirit of wanting to come up with my own design was willing to take a chance on it. He has a design on his website that is a variation of what I was thinking of doing. However I need to know if what i am doing is not needed or messing up in some way.

I need help in knowing exactly how to set up a design criteria.

What I want (in laymens terms) is a good all around system. Something that will chew up lows and highs at a nice out put level (don't need to entertain the neighborhood, but I would like to be able to crank it up when I want to jam). I will be using it as a stereo/home theater so movies are a must too. I like many types of music so instrumentals and Outkast are something I'd like to recreate.

Any suggestions?

I know I am being very general right now, but mainly I just want to know if what I am going for so far is way too much or not enough. I don't want to buy equipment and not use it properly.

Are 5 identicals and two subs too much/not needed/redundant? Would 3 identicals, two subs and a lesser pair of surrounds be better? I was thinking 5 so that everything should hopefully match in a good way.

Thanks again for the advice. Once a get a good design criteria down we can hopefully start talking about driver combos.
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Old 6th February 2007, 12:27 PM   #7
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You could model a tweeter in theory but there's not much reason to, WinISD is great for simulating your maxium excursion ect but you shouldn't be using a tweeter right on the edge of xmax anyway. Have a look at the FR graphs on the tweeter manufacturers website and use that as your low end response to begin with.

To start with keep it cheap, there's some lovely little speakers on the two site's I suggested in my last post that use components that won't break the bank. Something like this uses reasonably priced drivers, the crossover isn't too complicated and assuming an 80Hz rolloff to a sub can play at Dolby reference level given enough power. Which is more than loud enough for most people
You can simulate a woofers output in WinISD, to play to reference level the main speakers and surrounds need to be able to produce 105db at the listening position, the sub needs to be able to give 115db at the listening position. Model a woofer in WinISD, add an 80Hz 2nd order high pass filter and then adjust the signal strength until the SPL graph gives you 105db at 500Hz or so. Then check the cone excursion at that power, so long as you are able to produce 105db or whatever you're aiming for at whatever the distance will be between you and the speaker and stay within maximum power/excursion you're good.
-10db is the loudest I normally watch films at, which is loud enough to annoy everyone in the house and make the floor rattle 2 floors down To reach this level in theory the main speakers need to produce 95db at the listening position, that should give some indication how bloomin' loud reference level actually is.

Another alternative is the DIY Audio reference project, again reasonably priced and lots of crossover tweaking potential, the only problem is the Vifa bass driver is no longer in production

How big is your room and how far away from the main speakers will you be? This should give a good starting point in determining your requirements
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Old 6th February 2007, 11:59 PM   #8
JerMu is offline JerMu  United States
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Well hopefully the room requirements will be changing in the near future, but for now I am in my bedroom/theater which is about 14'x12' and I sit anywhere from 6'-10' away. However I do plan on moving in the near future and would like to have a nice living space or maybe even a separate theater. Should I plan on building a system for the current room, or is it possible to build around general requirements? something that might be okay in both applications. I mean if you have enough power for the big room you can alway turn it down to suite the smaller room, right?

When doing speakers in WinISD and say you get the sub to produce the 105db at the listening range as you mentioned before the fact that I'm planning on maybe having two subs would increase that output, right? Would it then be 210db or what? How do they add to each other?

Thanks again for the info, if it is a better plan to make my initial system for the room I am in now and then maybe upgrade later for round 2 then that is fine. I would rather do things right, rather than try to make a system perform in a way it was not intended.
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Old 7th February 2007, 12:19 AM   #9
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Every doubling of amplitude is +3db, to achieve 3db more output you need to double the power or cone area used.
Using the sub/s as an example, say one sub can produce 109db with 500 watts, adding a second increases your potential maximum output by 6db to 115db. 4 times the amplitude of a single sub, +3db for doubling the cone area, +3db for twice the power. For a single sub in this example to produce 115db it would take 2000 watts.

A sub capable of 210db would knock down your house, and the rest of the street

My room is 12' x 11' x8', a single 12" sub with 400w and single 7" woofers in the main speakers with 100w behind them is plenty loud enough
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Old 7th February 2007, 05:08 AM   #10
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No such thing as as sub capable of 210db. The limit is around 194db i think. At that point you get a vacuum, or near vacuum with each refreaction in the sound wave, making any further difference in pressure impossible.
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