Need help with 5.1 Home Theater design with donated SEAS and Peerless drivers.

Hi All,

A few months ago, a local community tinkering/making group (Hackerspace) I sometimes frequent was donated a large number of drivers from an audio supply place who was clearing out old stock.

They are:

Woofers: SEAS P17RE/P (Over 500 drivers)
Tweeters: SEAS 27TFF (Over 350 drivers)
Sub-Woofer: Peerless 830533 (I forget how many, but a lot)

I have taken my own T/S measurements of the drivers to the best of my limited abilities.

Woofer: Fs=90hz; Re=6.3Ohm; Qms=1.323; Qes=0.958; Qts=0.555; Sd=120cm^2; Vas=7.991litre; Spl=90dB/W/m

Tweeter: Fs=1025hz; Re=4.5Ohm; Qms=1.98; Qes=1.16; Qts=0.73; Sd=7.5cm^2; (looks like I didn't get the SPL sorry)

Sub: Fs=38hz; Re=2.7Ohm; Qms=8.52; Qes=0.497; Qts=0.469; Sd=353cm^2; Vas=63.651litre; Spl=90.46 Db/W/m

Nobody at the Hackerspace knows much about speakers, so I'm the guy (I know very little, although I've been bitten by the bug and am keen to learn and build).

I designed and built an MLTL in a TMM arrangement with MJK's worksheets, which i'm sort of happy with, but I don't yet have a mic to take proper measurements. I have the electronics to measure impedance etc. though.

The problem I have is that they have promised my father a new 5.1/5.2 surround system for his home theater in return for a donated piece of machinery, and I've been stuck in the middle of making it happen and designing a system.

What i'd like to know is, given the drivers available, is it possible to construct a reasonable or better home theater setup, and how do I go about doing it. I have like I mentioned a lot of drivers to play with, wood workers who could build me any cabinet I asked for.

The theater is a square room built for the home theater, with two levels, each one containing a row of 5 plush recliners as an indicator of size. I don't have exact room dimensions atm, but I can get them.

Any help would be greatly appreciated as i'm tearing my hair out here trying to figure out how to make this work...

Regards,
Andrew.
 

wintermute

Administrator
Paid Member
2003-08-03 11:43 am
Sydney
Quick search for the datasheets for the woofer and tweeter shows they are quite decent speakers. Maybe not the best match but I think it should be possible to use them together perhaps with a crossover point around 2500Hz... Can't find anything on the sub.

I'd look at doing two ways for the woofer/tweeter combo same for front and back. Do some modeling with something like unibox in a sealed enclosure and see how it looks.

Then do a design using the peerless for a sub (or perhaps multiple subs since you have a lot of drivers).

What aspects are you not happy about the MLTL?

Tony.
 
Joining the dots with rutager's recent post ... You're in Brisbane?


I don't have much spare time (work, newborn and a huge pile of unfinished projects to work on) but ...

I'm also in Brisbane. I have a calibrated mic and an spl meter ... Seems like they're the parts you're missing. I'm by no means a speaker expert but if you're not in a rush (to work in with my schedule) I could try to bring some stuff around to help get the speakers measured and have a yarn about ideas.

(Send me a pm if you're keen)

Chris
 

eriksquires

Member
2013-05-10 4:11 pm
What I would suggest, is invest some time in designing a good kit, then sell that kit for money. :)

Your community could make quite a bit of dough.

Are there local woodworkers who could make cabinets?

Of course, could always sell them on ebay individually, but it's kind of cool to think of your community having the most and best home theaters. :)

Best,


Erik

Hi All,

A few months ago, a local community tinkering/making group (Hackerspace) I sometimes frequent was donated a large number of drivers from an audio supply place who was clearing out old stock.

They are:

Woofers: SEAS P17RE/P (Over 500 drivers)
Tweeters: SEAS 27TFF (Over 350 drivers)
Sub-Woofer: Peerless 830533 (I forget how many, but a lot)

I have taken my own T/S measurements of the drivers to the best of my limited abilities.

Woofer: Fs=90hz; Re=6.3Ohm; Qms=1.323; Qes=0.958; Qts=0.555; Sd=120cm^2; Vas=7.991litre; Spl=90dB/W/m

Tweeter: Fs=1025hz; Re=4.5Ohm; Qms=1.98; Qes=1.16; Qts=0.73; Sd=7.5cm^2; (looks like I didn't get the SPL sorry)

Sub: Fs=38hz; Re=2.7Ohm; Qms=8.52; Qes=0.497; Qts=0.469; Sd=353cm^2; Vas=63.651litre; Spl=90.46 Db/W/m

Nobody at the Hackerspace knows much about speakers, so I'm the guy (I know very little, although I've been bitten by the bug and am keen to learn and build).

I designed and built an MLTL in a TMM arrangement with MJK's worksheets, which i'm sort of happy with, but I don't yet have a mic to take proper measurements. I have the electronics to measure impedance etc. though.

The problem I have is that they have promised my father a new 5.1/5.2 surround system for his home theater in return for a donated piece of machinery, and I've been stuck in the middle of making it happen and designing a system.

What i'd like to know is, given the drivers available, is it possible to construct a reasonable or better home theater setup, and how do I go about doing it. I have like I mentioned a lot of drivers to play with, wood workers who could build me any cabinet I asked for.

The theater is a square room built for the home theater, with two levels, each one containing a row of 5 plush recliners as an indicator of size. I don't have exact room dimensions atm, but I can get them.

Any help would be greatly appreciated as i'm tearing my hair out here trying to figure out how to make this work...

Regards,
Andrew.
 

jReave

Member
2012-10-30 4:34 pm
Given the number of drivers you have access to, I would kind of go wild and build speakers with multiple drivers, probably similar to a MTMWWWW or some variant where the Mids are still the same Seas driver as the Woofers but with the mids probably sealed and the woofers ported. Along the likes then of the Uluwatus.

High SPL's would be effortless.

If you have the space, I'd do the same for the CC with the MTM section stacked vertically and if space is more limited, just MTM's for the surrounds.
 
The room size is as follows.

6m*6m, looking at the screen, the roof on the left has a height of 3.2-3.3m, and it radius's down to 0m on the right with a 6.5m radius (the house is a Nissan Hut/airplane hanger design, the theater is on the top floor).

There is a step approx 300mm heigh, 2m from the back.

The floor is double layer mezzanine, the walls and roof are a two part expanding epoxy like they use to make props in movies, covered over a layer of polystyrene.
 

jReave

Member
2012-10-30 4:34 pm
Actually, I wonder if I didn't think big enough, for the front soundstage anyways.

I wonder if 2 x the Peerless sealed running in series might sound better than 4 x the Seas ported in the 60Hz to about 300Hz bandwidth? So perhaps a WMTMW and then run at least 2 more of the Peerless as ported subs (or perhaps sealed with eq boost - as the F3 doesn't appear to be that low) elsewhere in the room.

Or I wonder what a short line array might sound like with a couple of sealed Peerless above and below? I wonder if that would work with 4 x the 6.5" Seas for the midrange or if they might be a little too large in terms of C to C spacing. So, variations on some of the attached speakers below, perhaps not open back though.
 

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Hmmm, so a 3 way. The Peerless as a woofer, from 80hz to say 400hz, then the SEAS as a mid up to 2.5k, then the tweeter. Make the SEAS sealed, and have the woofers vented. Then the same Peerless used for the sub from 80hz to as low as they go. Alternatively I could use the SEAS to make a 3 way, can probably crossover about the same points, and make the mids sealed, run the woofers in a TL to extend the bass down as best I can.

I would like to be able to THX reference levels if possible.
 

jReave

Member
2012-10-30 4:34 pm
Well, I would definitely be thinking a 3-way. I mean, how many drivers do you have free access to?? But that's just the way that I think.

I suppose every sub driver is different - some can play up to 300Hz to 400Hz and some are better of with a limit of about 80Hz. The FR of the XLS looks fairly smooth to about 500Hz but it's a question of quality - will that range sound better with say, 4 of the Seas or with a couple of the Peerless? Unless somebody has specific knowledge/experience with them, which I doubt, you'd have to try each out, listening for differences or better yet comparing some FR, distortion and resonance measurements.

Remember also that distortion will be lower as more drivers are playing the same frequencies vs a single driver at the same SPL's and of course that the smaller drivers have to work harder than the larger ones too.

But when you are using subs, you don't have to have your mains go as low as possible, 60Hz to 80Hz should be fine, so I would think sealed for the XLS as mains (again, if they are good enough in that range) and just a typical ported alignment for the Seas as woofers would work.

Sensitivity in either case would be up around 90dB 2.83V/1m which is great, and I would thinkthat maximum SPL's of multiple drivers should indeed meet all of the THX specifications without breaking much of a sweat.
 

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Fenalaar

Member
2011-04-25 10:49 pm
The P17REX is a very good woofer. My brother, me and my father built a pair of Puls monitor, which is the P17REX and the H253 tweeter in a time-aligned cabinet. You may need to adjust a bit for tweeter sensivity, but those speakers are very, very good. Closed cabinet of around 20 litres, with a stepped front. First order crossover, if I recall correctly.

It was intended to be mated to a pair of pulse woofers, a humongous t-line, using the 13" Seas 33F-WBX-DD. I built a pair of those, with Peerless 12" driver, and active x-over. It easily went below 20Hz. The Peerless woofers you have are more suited to for 3-waythan a sub, I think...

Edit: Whoops - seems like I had a brain fart... The Pulse woofer used the 8" P21REX, not the 6,5"....
for the P17Rex, I'd suggest a 12 litre reflex box, tuned at 40Hz. First order x-over is possible with this woofer - it has quite a gentle rolloff. If wanted, make a stepped front, with a 3/4" plate, cut at 45 degrees on one side, so the woofer and tweeter centre are aligned over each other. Put heavy felt on the front to eliminate refections.

Johan-Kr
 
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Woofer: Fs=90hz; Re=6.3Ohm; Qms=1.323; Qes=0.958; Qts=0.555; Sd=120cm^2; Vas=7.991litre; Spl=90dB/W/m

Provided your measurement is right then the woofer suspension seems to have become stiff during the long storage time. The major question before designing a speaker with these units is whether the problem disappears after some use or not. In the latter case you will not be able to achieve an acceptable bass output and the units only will serve as midrange drivers.
 
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Fenalaar

Member
2011-04-25 10:49 pm
The t/s parameters are way off. I'd suggest connecting a pair to an amp, with one of them in reverse phase, put them face-to-face and feed them noise (out of tune radio) at a moderate level (normal listening volume) for a couple of days, and then re-measure. A silicone stick (like you use on car door rubber lists) might help in maintaining the surround...

Johan-Kr
 

jReave

Member
2012-10-30 4:34 pm
Hmmm, from memory there are less than 100 subs, and I don't want to use them all, I might be better just stacking the SEAS to get the sound I want, and using the Peerless as subs, since there are 500ish of the SEAS, it's not really a problem :p

Fair enough. Mind you with 2 true subs, it would have been just a total of 8 Peerless all together but I get that other people might want to have access to them as well.

It might also be helpful to define what the max SPL is that you want. I can't remember the THX specs of the top of my head. Is it about 90dB or 95dB, plus room for 15dB peaks? So somewhere in the neighborhood of 110dB 1W/1m?

Also, how much power does your dad's receiver have and is it comfortable with 4ohm nominal speakers?

If I understand the room layout correctly and if it is possible, I would consider changing the room orientation as well. For home theatre, side to side symmetry is quite important in my book so I would therefore try to have the sloping end of the ceiling at either the front or back of the room not on one of the sides, preferably at the back I would think. Also, any chance your dad has some room treatment in there already because that will really help things as well?
 
85db at -20db reference for all channels, subwoofer is 95db @ -20db reference. Dad will need a new receiver, so that's not an issue. It's not possible to change the room orientation either, the slope is too great, if it were at the back, you couldn't mount the projector, if it were at the front, you couldn't mount the screen, so...

My limited understanding was that each channel should ideally be the same? So for an MTMWW setup, you'd probably have FL, FR, RL, RR, as MTMWW, then the centre as WMTMW, + the .1 dedicated woofer. So that'd come to 12 Peerless, as you'd probably use two of them in the sub?

So with these sorts of boxes, where you have a crap-ton of mids and woofers, why do they only use one tweeter, the isn't the SPL of the tweeter going to be too low in comparison?

I'm sorry if I'm bugging people, I'm really kind of lost on this, and the more I read, the more confused I get.

I've got a couple of drivers, will put some silicon on them, and do that and see if they improve.