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Starting a new project out of a pair of 104ab's
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Mike G
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Joined: 04 Apr 2009
Posts: 19

PostPosted: Wed Apr 15, 2009 9:28 pm    Post subject: Reply with quote

Thanks for the links guys.

I have come to reolize that one of the crossovers has either some type of failing part or a loose connection/cold joint. I have had some drops in level from one of the speakers qutie frequently but I always thought that it was coming from my rather beat up power amp (also needs replacing). But when looking over the crossovers moving it around caused the woofer to dip out momentarily. I replaced the wires to the B200 just to make sure it was not that.

I spoke a friend at my local shop and it would cost a bit of dough for him to look them over. This is before parts and so on. All this combined with a new tweeter going in has me wondering if I should just replace the crossovers.

The other thing that has me thinking that this would be a good idea is the fact that all the tweeters I am looking at can be crossed over lower than 3k. The lowest being 2k The highest being 2.5k. I would love to take as much strain off the B200 as I can to try and get rid of some break up frequencies.
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Mike G
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Joined: 04 Apr 2009
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PostPosted: Wed Apr 22, 2009 3:26 am    Post subject: Reply with quote

Well this project is moving forward. I just ordered a pair of Vifa xt25 tweeters and they should be here by the end of the week. These tweeters do not like to be crossed over all that low. Around 2k at the most. At first I am going to try and see how close I can get by simply compensating for sensitivity between the B200 and the XT25. I am hoping that this gets me a decent result. I could see trying to bring the crossover frequency down to around 2k but that is down the road. And may never happen.

I have also ordered a "gainclone" kit from AudioSector.com I am very curious to see how it will drive the 104's. Has anyone here worked with a gainclone type amp?
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Mike G
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Joined: 04 Apr 2009
Posts: 19

PostPosted: Wed Apr 29, 2009 3:34 am    Post subject: B200A, B200H, QB200H What are these? Reply with quote

Even though I may be talking to myself I dare to keep posting at the risk of seeming obsessed Shocked
Ok so the tweeters arrived last week and I have had a chance to take a listen to them through the existing crossovers. They sound great but they are going to need some coaxing to get them to blend in with the B200

I in trying to either modify the existing crossover or simply build a new crossover for the tweeters I found a program called that has included models for some of the B200 drivers but they are named with letters in place of numbers. They are ...

B200A
B200H
QB200H

Please tell me that one of these is the B200 SP1039. If so then I would actually have the information to build my own model of the 104. That would be exciting for me.
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speakerguru
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Joined: 18 Nov 2005
Posts: 958
Location: Green Hut, Tovil

PostPosted: Wed Apr 29, 2009 8:21 am    Post subject: Re: B200A, B200H, QB200H What are these? Reply with quote

Mike G wrote:
Please tell me that one of these is the B200 SP1039.


No such luck, but don't worry about it, because there's no way you can do crossover design from just paper specs. You need to be able to measure acoustic amplitude and phase, at least on the listening axis you intend to use. If you can't, then you'll need to do a lot of wishing and hoping and keeping your fingers crossed............
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proffski
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Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Wed Apr 29, 2009 8:49 am    Post subject: Re: B200A, B200H, QB200H What are these? Reply with quote

speakerguru wrote:
Mike G wrote:
Please tell me that one of these is the B200 SP1039.


No such luck, but don't worry about it, because there's no way you can do crossover design from just paper specs. You need to be able to measure acoustic amplitude and phase, at least on the listening axis you intend to use. If you can't, then you'll need to do a lot of wishing and hoping and keeping your fingers crossed............


Agreed! When I built my first proper loudspeakers from paper specs back in the late '60s I was so proud of them, there was something lacking but hey, they were my speakers!
I used the beasts till around '74 when I had a chance to have them tested at the college where I worked.
After that they somehow never sounded the same...
I lost count of all the projects that took place in the following years. It is interesting that I have gone full circle and now only like sealed enclosures and electrostatics. I alse re-iterate that the most accurate bass I have ever heard (not the deepest) was from the B&W DM70 which also sadly suffered from low power handling and made me upgrade to Quad 405 IIs at the time, another story...
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Mike G
Junior Contributor 10+


Joined: 04 Apr 2009
Posts: 19

PostPosted: Wed Apr 29, 2009 2:46 pm    Post subject: Reply with quote

Thanks guys.
I none the less am stuck with the current situation and need to make the best of it. I simply cant go out and buy a pair of new speakers. Also there is a lot of sentimental attachment to these speakers for me. Besides that I know the low end of these speakers inside and out. For my use that outweighs absolute mathematical accuracy. This being said I am not in a huge hurry and I already have some pro audio equipment so I am at least part way there to having a amateurs test bench.

I have multiple computers, high quality sound cards, Echo, RME, Sonic Core-Creamware, Mackie, a good quality analog mixer, microphone and preamp. I have been looking at Speaker Workshop but I am not about to build there "Jig". I already have to much on the go at the moment to start building there hardware. Is there any basic software/freeware that allows for the basic measurements with out the need for dedicated hardware? If so I am good to go! If not then it is going to be me running online calculations from specs. Indeed not ideal but it may be all I have at the moment.

In the case that I do not have what I need to do proper measurements does anyone here have a Speaker Workshop speaker profile for the B200 SP1039?
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