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Old 22nd August 2011, 09:02 AM   #1
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Default Enclosures for Old bose drivers

I want to build a pair of speakers for my "fresh air" shop. Here is what I am currently using for my sounds and where I am starting from

IMG_0074.JPG


I call it my speaker tree, lol. I am looking to upgrade….

I bought the following so far or my start so to say,
- Lepai Tripath TA2020 Class-T amp
-Bose 901 Drivers off of ebay. They are about 4.5" in diameter.

I am looking for an opinion on what time of enclosures to build. I really like the horn designs but I think that I will need a bass reflex type of cabinet. So I am looking at the
Floorstander Mk ii from Planet 10. I plan on building the speakers out of pine and fir from my local homecenter. I have been reading a lot of forums but I am lost when it comes to some of these charts etc.

Thanks,

Gus
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Old 23rd August 2011, 11:53 PM   #2
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I would start by trying to find the TS parameters. Once you have those you can model ported, back loaded horn and transmission line and see what looks best. Without the parameters you are pretty much stuck with sealed or some cut and try.
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Old 24th August 2011, 12:29 AM   #3
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The TS parameters are not published, unless some hobbyist found them and posted. It matters which version of the Bose 901 they are out of. Early drivers are likely to have foam surrounds that are rotted or rotting - a common problem in all foam surrounds.

If they have cloth surrounds, ur ok.

You can measure the T/S parameters yourself, it's not that hard.

The original design of the 901 used a sealed box with massive amounts of LF and HF boost to get a "flat" response that was also wide range. You can count on these speakers to be more or less "midrange" drivers without EQ.

I suggest you plan on adding in a tweeter at ~1.5 - 2kHz. No big deal.

One way to go is with a single line source, one driver on top of the next... the only question will be the box volume, which will depend on the T/S parameters. The ones you want are Fs, Qt and VAS.

So, regardless, and unless you plan on adding in EQ (if you stack them as a line source, then you have an "improved" version of the 901) you will then need a speaker or speakers for the BASS...

Btw, you will use a series parallel wiring arrangement, like BOSE did originally...

Alternately you can put each driver in its own volume and stack or array them...

Regardless, you have a project now that will open the door to you about speakers, speaker design and fun!

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Old 24th August 2011, 02:21 AM   #4
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Hefty?
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Old 24th August 2011, 07:27 AM   #5
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Thank you guys for you responces. I will try to look up all the infromation and direction that you have given me. But please forgive me if i come back with more questions. I am a total newbe to all of this. Some of bear's terms have me off tilt. lol.

here is the information that the seller gave...


For Sale is a Pair of Original Bose 901 series I or II full range 8 ohm driver speakers they will fit in most 901's. They are in excellent working condition, and have been tested, no buzzing or scraping. Ohm readings are 7.5 & 7.6 ohms, # 25-100441 24729 285206. No Dents, rips or tears no damage these and have the cloth surrounds so they will not get foam rot.

These are some of the best full range drivers out there, they just have that Fantastic Bose Sound & Bose Quality. Perfect for replacements or use in small monitors. These create an amazing soundstage and unbelievable sound quality and detail for single driver setups. Also excellent for mid range or extended frequency mid-bass. 4 1/8" cutout diameter, 4 5/8" OD, 5" diagonally, 1 3/4" depth
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Old 24th August 2011, 03:10 PM   #6
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pictures?

the seller's hype is just hype... except as noted: "excellent for mid range or extended frequency mid-bass"...

You can figure this stuff out... there is a lot of information here on DIYAudio if you search and read... as well as a ton of tutorial sites online... feel free to ask questions, but please do try to figure it out first?

_-_-bear
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Old 24th August 2011, 04:07 PM   #7
18Hurts is offline 18Hurts  United States
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Gus,

Your open air shop--aka under an overhang to work on stuff and listen to tunes? Since you're playing with a T-amp, I'm assuming a simple system that gives decent sound at a decent volume.

I just built my garage speakers--fed with a old receiver pushing 45 watts per channel. Since the garage has metal walls--I wanted something that would overpower reflections, be very efficient, give a very tall sweet spot, unique and ugly as sin. Next thing I know, there are a pair of 6 foot 2 inch tall vertical line arrays in the place and it does do what I want it to do. It sounds the same if I'm standing, sitting or laying on the floor so goal achieved.

Are you trying to build line arrays with 8 Bose 4.5" speakers per side or just prefer to use one or two of them per box? Arrays need EQ and if running full ranges--a ton of EQ! If it is only one or two per side, I'd go with something else. The low amount of power you're playing with leads me to something more along the lines of a PA speaker. Use one of those 12" "full-ranges" with a helper tweeter and a single capacitor for a very efficient speaker that is simple to build, sounds decent and gives a "big sound".

The full-range guys like the combo of an Eminence Beta 12 LTA ($65 each) crossed over at around 8 KHz to a single Fostex "super tweeter" ($43 each). It can be put in a 1.75 cubic foot sealed box, ported boxes or the giant BiB horns.

Eminence Beta-12LTA 12" Full-Range/PA Driver

Fostex FT17H Horn Super Tweeter: Madisound Speaker Store

If cost is an issue, the Pioneer AHE60 horn loaded tweeter is also a good match--$12 each.
http://www.parts-express.com/pe/show...number=270-050

If you want clarity above all else, and the cost is not an issue--get the Fostex FT-17. I figure these speakers will be sitting outside so the Pioneers might be a better idea to prevent theft.

I was going to build the Beta12/FT-17 system in a BiB horn type enclosure but got side tracked with vertical line arrays. Went with the arrays since that design is the best for marginal spaces--my garage for instance.

Maybe your desire is a pair of single full-range speakers for simplicity? If so, look at Fostex, Mark Audio, Fountek, Tangband just to name a few.

What is your budget?
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Old 24th August 2011, 09:18 PM   #8
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Why do you say that arrays require EQ?

Their response is essentially that of a single driver - no worse, no better.

The BOSE drivers would need EQ if you wanted "full range" response, but if they are augmented with a woofer and a tweeter - not, and you get pretty good sensitivity plus lower distortion and a single midrange at the same SPL... generally speaking.

The other alternatives are viable though...

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Old 24th August 2011, 09:50 PM   #9
freddi is offline freddi  United States
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IIRC the old 901 driver has Re around 1 ohm. Here's unequalized response of one of my 901's outdoors with mic: facing the single driver, then 8 driver array, then with the cabinet near a house wall with mic facing the single driver. The other graph is the EQ box response. This is the old/sealed 901 with cloth surround drivers.
Click the image to open in full size.
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Old 25th August 2011, 12:20 AM   #10
brsanko is offline brsanko  United States
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If you like the small horn designs why do you think you'll do bass reflex? A horn will out perform BR in every way. If you manage to find the T/S parameters, let me know how low you want to go with them and how many drivers per speaker and I would be happy to design a good horn for you.
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