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Multi-Way Conventional loudspeakers with crossovers

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Old 10th October 2012, 05:06 AM   #381
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nice website Bob
I know i "just jump in" but I learn slowly and still make all the mistakes in the world, i blame the ringing in my ears.
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Old 11th October 2012, 03:48 AM   #382
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Quote:
Originally Posted by Moondog55 View Post
Problem with the ScanSpeak and SEAS drivers is most beginners are on a much lower budget
I know what you mean but there are some in their range that can be had for less than the D27TG/P13 combo such as the Discovery series. Of course there are other manufacturers and for example, my SEAS 27TFFC (old version) + Peerless 850488 which cost less, kills the above but the drivers are no longer available.

I think PeteMcK is on the right track as I recently moved to larger 6.5" woofers in a similar size box (10 litres) and just adds so much more body to the music even though the F3 is higher (F6 and F10 is much better due to the sealed loading). It uses a Peerless 810921 + Vifa XG18WH00-08 and was designed to do nearfield work and be better than a Yamaha NS10M I had years ago for this duty.

What I'm saying is, the larger woofer would allow more flexibility in the design as allows for small bookshelves as well as floorstanders which is not generally possible with 5" drivers. For example, the XG18 (now gone) can be used in 10 litres sealed (F3=66Hz) but also 22 litres vented (F3=42Hz) which means it can suit more users. I'm sure PeteMcK's suggested combo of SEAS CA18RLY + 22TFF could do that and there would be plenty of other other combinations.
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Old 11th October 2012, 04:24 AM   #383
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True
Although most here would know my own preference for 2.5 or proper 3-Way speakers the original was one of the nicest iterations I have listened to.
The simplicity of the design and build was the greatest asset of the whole project, it really was difficult to make it sound bad.
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Old 11th October 2012, 06:54 AM   #384
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Agree. I like my main 2.5 way and other large speakers but this little speaker was a good low cost step into the hobby which was the intention. A low crossover part count (3 components in most cases) helped to keep costs down without causing too many problems with the drivers.

I haven't looked around in recent times for other drivers that would keep a design so simple. I'm sure there are plenty out there and just takes patience and modelling to find what's suitable. As I've said before, get the driver choice right and you are more than half way there. I'm sure there will be suggestions forthcoming and maybe eventually another simple design with current drivers.
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Old 11th October 2012, 07:08 AM   #385
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The one main problem I see for a suitable project is simply that the drivers ( Peerless) that have suitable parameters and smooth responses have truncated frames which make for difficult woodwork ( actually that is the main reason I haven't bought any ) and I think beginners are better off with a round frame, just because they are easier to deal with. Although most of those medium sized Peerless woofers look like they would need a second order XO at the top as they all do seem to have that peak just before they roll-off.
Starting with an 8inch bass and a decent 3 or 4 inch full range means getting into low XO frequencies and corresponding higher cost of the components.
I always thought that Jason should organize a limited run of close tolerance P-13s and D-27s for the forum members and sell the kit via the web
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Old 11th October 2012, 10:18 PM   #386
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re:'I'm sure PeteMcK's suggested combo of SEAS CA18RLY + 22TFF could do that ' - the downside of that combo is that it requires something in the order of 30-40 L (I used 38L), perhaps substitite CA18RNX?, but part of the charm of this combo I think is because the box is doing just the right amount of the low end work. Re: price, Seas aren't the cheapest & a bit of a pain to get from NZ, but definitely win in quality per dollar stakes...
FWIW I prefer this combo to my main 3 way, which uses the aforementioned unobtainum Peerless 850488s..
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Old 12th October 2012, 03:05 AM   #387
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Peerless truncated frames can be a pain to rebate but can always be installed without a rebate and there are some other tricks with corner mouldings. I wouldn't use a Peerless for a long term project as they used to change models rapidly. You get a design going and the driver disappears.... ala 850488. The 830875 for example seems to be an exception as been around a while but has had a few manufacturing changes which doesn't help.

Comes back to the Scan Speak, SEAS camp for long term supply.
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Old 12th October 2012, 03:47 AM   #388
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OK those are very relevant points.
Also PeteMcKs points about size are very pertinent.
A beginner project is probably much better around the 10 to 15 litre internal box volume, this is a very acceptable size for good WAF as well as needing little if any internal bracing but as Pete says it does limit you to a maximum driver size of around 150mm ( 6 inches ) and my preference for the P-13s is because they seem to have the best reproduction of the midrange/female voice and I listen to a lot of female voice on recordings.
So a driver that works well in a small box, works well either sealed or vented having a smooth roll-off so XO work is relatively simple and with enough bass to work as a 2-way and having good midrange reproduction and also affordable, what could be simpler?

This next project isn't for me BTW,
We have 4 untouched P-13s in the cupboard so I am set for a while ( also I prefer the M-11 from Vifa as a dedicated MR ) especially my modified 16R rewinds for use in MTM

So for all the lurkers watching this thread Start looking for suitable drivers
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Old 12th October 2012, 03:54 AM   #389
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The closer together the mid and tweeter drivers, the wider the nodal lines at the crossover frequency where both drivers are putting out the same thing at about the same time, shifted only in phase, so the sound at the crossover frequency region integrates better (less ripple that varies depending on the angle of the listener to the speaker). Getting this right can be difficult (why I often use high order crossover rates - so a smaller percentage of the spectrum gets marred).

Having said that, The three inch Peerless I mentioned above is so difficult to mount that I'm rear mounting it on 1/2 inch MDF, with a routered three inch hole (so the hole flares out - to minimize cavity effect) , and instead of using the tiny mounting holes on the minimal driver frame, I'm using fender washers with a #6 woodscrew, screwed into the panel just outside of the driver mounting holes, with the washer holding the corners of the driver to the panel... Sort of ridiculous, but it works.

In a line array, you might want the tight tolerance minimal frame so the drivers can be right up against each other, for minimal comb filter effects. For that, I'd look into having an 1/8 inch thick brass front panel specially fabricated, just wide enough for the drivers to mount. That might be expensive.

The cool thing about the 3 inch is that it does a great job (very flat response) from 110HZ - 6kHZ (in a closed box) where it gets arguably a bit too directional, which means no crossover anomolies anywhere in the parts of the frequency range that have to do with good imaging (100HZ - 6kHZ) . Above 6kHZ it's well documented that humans have a hard time pinpointing image location anyway. 8kHZ allegedly usually sounds like it's coming from above the speaker. And when you only need a tweeter to come down to 6kHZ, there are MANY good choices, many of which are relatively cheap. A Fountek 1 inch ribbon if you want a big mounting frame is one good choice. The tiny Dayton 3/4 inch also mentioned above is another (but is difficult to mount as well, in it's own way).
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Old 12th October 2012, 04:38 AM   #390
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I think I missed something here Bob, are you suggesting the 3 inch as the woofer for the new project? If so I couldn't find a link in your previous post and as Rabbitz noted Peerless change their driver catalogue very quickly.
I just visited the Tymphany website and found no 3 inch that i would have said had any bass to speak of in a reasonably sized room, look like F3s in the high 80s which would satisfy most beginners i think
As for the position of the XO point, I find it less of a problem than most people when using the better ( smoother ) drivers and I can live with crossovers anywhere in the region from 2500 to 6000Hertz, I don't think any project using anything more than second order is feasible for beginners ( which as pointed out is the whole point of this particular reference project.
Simpler the better works for me
Personally I bi-amp/tri-amp on the low end
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