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post #11 of 21 Old 07-27-13, 05:28 PM
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Re: passive crossover

This is what happens to the crossover when a 4 ohm resistor is placed in series with the tweeter to (equalize) the load seen by the amp.
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post #12 of 21 Old 07-28-13, 12:00 AM
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Re: passive crossover

Thanks for the great input Kiwilistener, it highlights the need to research the drivers to be used and how they interact.
After choosing drivers you need to model them to see how they work together and, if unsatisfactory, look at what else is available.

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post #13 of 21 Old 07-28-13, 04:24 AM
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Re: passive crossover

Quote:
robbo266317 wrote: View Post
Thanks for the great input Kiwilistener, it highlights the need to research the drivers to be used and how they interact.
After choosing drivers you need to model them to see how they work together and, if unsatisfactory, look at what else is available.
Agreed. Choosing drivers that match well is without doubt the most important first step once one has decided on the type of speaker they want to build.
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post #14 of 21 Old 08-01-13, 06:35 AM Thread Starter
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Re: passive crossover

Thanks for all the info guys. Went back to the drawing board on this.
Decided to order Harris techs crossover design program to help me along.
Hopefully I can post some results later this year.
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post #15 of 21 Old 08-01-13, 02:19 PM
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Re: passive crossover

Good luck with the project and if you have the time a build progress thread would be cool too.
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post #16 of 21 Old 08-01-13, 03:03 PM Thread Starter
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Re: passive crossover

Ye no problem
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post #17 of 21 Old 09-03-13, 02:17 AM
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Re: passive crossover

Troels Gravesen has a published design using these drivers. I hear he is pretty good
http://www.troelsgravesen.dk/Peerless_HDS830860.htm
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post #18 of 21 Old 09-04-13, 12:04 AM
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Re: passive crossover

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PlanoDano wrote: View Post
Troels Gravesen has a published design using these drivers. I hear he is pretty good
http://www.troelsgravesen.dk/Peerless_HDS830860.htm
Yes he is a good designer, I'm currently building a slightly modified version of his PMS. Build thread here.

The drivers Troels used for his design , differ slightly from the mid-woofer the OP is using, however its interesting to note that the crossovers, both his and mine put the sweet-spot at about the same frequency. His x-over is interesting as he uses a combination of factors to arrive at the best result. The crossover I suggested for the OP to view is not necessarily the final iteration but rather a starting point. The really interesting thing is the differing method the software packages use to basically arrive at the same point. I've run the sim through PCD and its very close to both x-overs. I generally don't use PCD for crossovers as I find its somewhat overkill for smaller builds, and is a little too complex for most DIYer's.

That said I note the output power for these speakers is 50watts RMS max, which is also a little lower than the OP was looking for, however on a mid sized amp they should work well combined with a small sub as they dont have a great deal of bottom end, and if you build to the size Troels did I'm not sure how much bass they would produce.

To be honest I don't design anything under a 15 liter enclosure size, and don't use drivers smaller than 6 inches as there isn't generally enough bottom end with smaller drivers. ( as always there are exceptions to this ) but for most Hi_Fi reproduction that's generally the smallest I go.
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post #19 of 21 Old 09-04-13, 01:05 AM
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Re: passive crossover

Kiwilistener
I took a look at your PMS thread. That is a very ambitious project and looks like you are pulling it off wonderfully. I do not have the wood working skill (patience) to pull off any of Troels Gravesen's designs but admire his contributions. I also agree with the point you made on woofer size for Hi-fi listening.
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post #20 of 21 Old 09-04-13, 02:34 PM
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Re: passive crossover

Hi Dano.

I built my first set of speakers circa 1974, using Plessy Davred 8 inch paper cone drivers. For the tweeter this was a paper cone 2 inch unit. The crossover was a capacitor for the tweeter and a coil ( transformer style) for the woofer, if memory serves. These came as a kitset with a book on speaker building. One of the comments in the book was that the bigger the room the bigger the drivers should be.

Thats a little simplistic but it generally holds true. A good quality 8 inch woofer should out perform one or even two 6 inch drivers. There are of course six in drivers that can go toe to toe with some of the eights, hence my comment regarding six inch drivers. My lounge is reasonably large and is also my listening room, at 8 x 6 x 3.5 or 25' x 18' x 10' . That's a good volume to fill and my latest version of the "Pettites" are 15 liters using a 6.5 driver and do very well, but for the same power output from the amp through my Mains, blows them out of the water without breathing hard.

Bass response is good in the smaller speaker but is much more room filling and effortless for the same power from the larger speakers. We had both running using the Sugden 21se amp recently. At 35 watts rms it not a big amp, but the sheer quality of sound from the big speakers was lightyears ahead of the Pettites.
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