Help with xovers please

john & Jake the dog · Mon Sep 10, 2007 10:36 pm

Hi,
not been here for a while but I was persevering with the other place but I have found no answers to my queries of late, apologiesi n advance for requesting help here.
I am putting a 2 kef B200's in two boxes, ex Mission 710's, to use as semi subs for my clydes. I need to add to the clydes crossover.
I posted:

I think I'm starting to get my head together on this but am still puzzling with parts of it.
I have read that 400hz may be a better crossover position to use the B200 as a woofer.
according to this:

I need an inductor of 3.3 and a cap of 5 uf.
I know the inductor should go to the woofer pos line but am I right in thinking that the cap should go on the midrange to stop it going down further than 400hz, if so, if I post a schematic of the Clyde crossover could someone please tell me the position.
Glad of any assistance in this.

Any tips for me please?

pre65 · Post by **pre65** » Mon Sep 10, 2007 10:57 pm

Hi-i'm no speaker expert but with a bit of "Googling" i found a crossover schematic for a 3 way using the B200 as the woofer.

So this may help ?

http://homepage.mac.com/planet10/TLS/cl ... xo-map.gif

Post by **Nick** » Mon Sep 10, 2007 11:08 pm

Just to be certain we know what your are doing, ar eyou leaving the cllydes as they are and building a seperate sub out of the b200's?

I guess that using the inductor will create a 6db/octave filter for the "sub", but I am unsure if you can just put the cap infront of the clydes as it is, I would think the load they will provide will combine with the cap to produce a strange response.

I guess there is no harm is using the clydes full range, they would normally be used that way anyway.

Or am I missing what you are trying to do?

john & Jake the dog · Mon Sep 10, 2007 11:28 pm

Hi Phil and nick,
I can't seem to post what I want to say, lost my post 3 times I'll try again.

pre65 · Post by **pre65** » Mon Sep 10, 2007 11:32 pm

Hi-i believe some on the WD forum used to have this problem with long posts and got round it by creating the post in another programe (word or wordpad ?) and then cutting and pasting to the forum message box.

john & Jake the dog · Mon Sep 10, 2007 11:33 pm

Hi Nick
It seems I can't post pics.
I am putting the b200's under the clydes as I like their mid and top.
I think I know how to wire the B200 with an inductor and a cap.
But i think I need a matching cap in the clyde xover to cut it at 400hz.
I presume it has one to cut it at around 50hz unless it rolls off naturally.
So I don't know where to put this cap, would it be in the poitive line to the mid?

john & Jake the dog · Mon Sep 10, 2007 11:35 pm

Hi phil, thanks for searching.
I found a Kef diagram to cross the B139 at 400hz, which should do for the b200 but I can't post it until I've posted a while.

pre65 · Post by **pre65** » Mon Sep 10, 2007 11:47 pm

Hi-here is Johns Kef picture he wanted to post

john & Jake the dog · Mon Sep 10, 2007 11:53 pm

Many thanks Philip,
I know it is a B139 but the values seem to fit with what I want for the B200.

pre65 · Post by **pre65** » Mon Sep 10, 2007 11:56 pm

Hi-i notice the B200 was available in several versions,some with stronger magnets so i dont know if the crossover details would be the same for all of them ?

pre65 · Post by **pre65** » Mon Sep 10, 2007 11:58 pm

Hi-here is a picture of Johns Clydes with the Mission box (for the proposed sub) underneath.

Post by **Nick** » Mon Sep 10, 2007 11:59 pm

Well, I guess my question is what do you want to achieve?

I ask this, because I am sure you are not doing this for fun, but there is maybe a lack of bass on the clyde that you want to fix.

Personally, I think its going to be hard to passivley cur the bass of the clyde without having other unwanted effects, so maybe a solution would be to let the clyde do its thing, and just bring in the sum under that.

Or possibly better, is to use two amplifiers, it will be easy enough to add passive xovers before the amplifiers to do what you are trying to do.

Maybe see what the cheapest second hand amp you can find in somewhere like price converters and use that for the sub. It will be a lot simplier to just use caps and resistors then to make high and low pass filters before the amps.

And if you don't like the result, your clydes escape untouched.

BTW, the forum doesn't allow pic's or URL's untill you have posted a minimum number of normal posts, it helps us keep spam at bay.

john & Jake the dog · Tue Sep 11, 2007 12:02 am

Thanks again Philip.
The ones I am getting from Andrew Ivimey are the common smaller magnet ones.
I know I will probably not get the values right first time,I'll just have to play it by ear and adjust accordingly, bit of a long time exercise I fear.

pre65 · Post by **pre65** » Tue Sep 11, 2007 12:06 am

Hi-i still have a pair of SP1004 Kef crossovers in my box.

On the Kef kit3 i replaced them with upgraded Wilmslow Audio ones.

john & Jake the dog · Tue Sep 11, 2007 12:10 am

Hi Nick,
The Clydes are wonderfully clear in the mid and top and they do go down a bit but the bass sounds a little manufactured and artificial.
I like the kef sound from my Isobarik love affair and so for a minimum outlay I thought I would experiment a little.
The Clydes were £19 the Missions a pound and Andrew has given me a great deal on the B200's.
As money is tightish I thought I would go the passive route.
I have a spare amp but I thought matching a transistor amp to the Kel84 might prove difficult.
And I find it fun anyway.
Can I post piccies now please.

audio-talk

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