Alterations to BAMTM crossover?

lowpsiTSi · 25th December 2010, 08:06 PM

I'm in the middle of building a pair of Zaph's BAMTMs and instead of going with the Seas tweeters, I went with the HiVi SD1.1-A found here. I am regretting not going with the Seas now but I hope the HiVi will produce a reasonable quality response. I know the frequency response is not similar to the Seas along with some other things, before I goto order the crossover components, I was wondering if there was any alterations to the component list I should make? Any help would be appreciated.

And on another note, my searches have been coming back empty on what type of amplifier to employ for these speakers? I'd love to build one and I am all about the DIY, I just haven't had any hands on experience with audio fidelity of this amplitude. Thanks in advance!

woof · 26th December 2010, 02:33 AM

I would save my money for the Seas tweeter. What makes the design work is the ability of that tweeter to cross over low. Not only will this require a complete redesign of the crossover, I doubt your tweeter will play low enough to work with the woofers. It is a great design that sounds fantastic with 75 - 100 watts of clean power.

sreten · 05:09 PM

Hi,

Your asking for trouble changing the tweeter, I don't recommend it at all.
Its not totally unworkable with the SD1.1 but some redesign and modelling
would be required for the new sensitivity and series resistor value.
There is no guarantee the SD1.1 can handle the same maximum levels.

Any decent 4 ohm capable amplifier should be fine. FWIW buying a used
and rebuilding it is far easier that starting from scratch, and far cheaper.

rgds, sreten.

http://sites.google.com/site/undefinition/diy
http://www.zaphaudio.com
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.rjbaudio.com/

lowpsiTSi · 18th January 2011, 03:06 AM

I know it was recommended that I pick the Seas tweeter over the HiVi. But I am hesitant to pay $90 in tweeters. If I was to move forward with the HiVi SD1 and used the crossover design this guy made up here.

lowpsiTSi · 18th January 2011, 06:43 PM

Would that work? Or am I missing something.

BobEllis · 18th January 2011, 09:21 PM

Yes you are missing something. The tweeter filter is only part of the crossover. If you found a crossover that gives the same frequency and phase response as Zaph designed into his on the same baffle width, you could substitute it. That is not the case with the filter that you linked to.

Notice that Zaph gets a 4th order 1500 Hz response out of his filter. The one you linked to rolls the tweeter off at about 2300 Hz third order You'd end up with a big hole in the response.

lowpsiTSi · 19th January 2011, 12:47 AM

Ok that makes sense. I will have to find a tweeter with a lower frequency response.

25th December 2010, 08:06 PM	#1
lowpsiTSi diyAudio Member Join Date: Dec 2010	Alterations to BAMTM crossover? I'm in the middle of building a pair of Zaph's BAMTMs and instead of going with the Seas tweeters, I went with the HiVi SD1.1-A found here. I am regretting not going with the Seas now but I hope the HiVi will produce a reasonable quality response. I know the frequency response is not similar to the Seas along with some other things, before I goto order the crossover components, I was wondering if there was any alterations to the component list I should make? Any help would be appreciated. And on another note, my searches have been coming back empty on what type of amplifier to employ for these speakers? I'd love to build one and I am all about the DIY, I just haven't had any hands on experience with audio fidelity of this amplitude. Thanks in advance!

26th December 2010, 04:55 PM	#3
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Your asking for trouble changing the tweeter, I don't recommend it at all. Its not totally unworkable with the SD1.1 but some redesign and modelling would be required for the new sensitivity and series resistor value. There is no guarantee the SD1.1 can handle the same maximum levels. Any decent 4 ohm capable amplifier should be fine. FWIW buying a used and rebuilding it is far easier that starting from scratch, and far cheaper. rgds, sreten. http://sites.google.com/site/undefinition/diy http://www.zaphaudio.com http://www.rjbaudio.com/Audiofiles/FRDtools.html http://www.rjbaudio.com/ __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow Last edited by sreten; 26th December 2010 at 05:09 PM.

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26th December 2010, 02:33 AM	#2
woof diyAudio Member Join Date: Feb 2007 Location: Irving, TX	I would save my money for the Seas tweeter. What makes the design work is the ability of that tweeter to cross over low. Not only will this require a complete redesign of the crossover, I doubt your tweeter will play low enough to work with the woofers. It is a great design that sounds fantastic with 75 - 100 watts of clean power.

18th January 2011, 03:06 AM	#4
lowpsiTSi diyAudio Member Join Date: Dec 2010	I know it was recommended that I pick the Seas tweeter over the HiVi. But I am hesitant to pay $90 in tweeters. If I was to move forward with the HiVi SD1 and used the crossover design this guy made up here.

18th January 2011, 06:43 PM	#5
lowpsiTSi diyAudio Member Join Date: Dec 2010	Would that work? Or am I missing something.

18th January 2011, 09:21 PM	#6
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	Yes you are missing something. The tweeter filter is only part of the crossover. If you found a crossover that gives the same frequency and phase response as Zaph designed into his on the same baffle width, you could substitute it. That is not the case with the filter that you linked to. Notice that Zaph gets a 4th order 1500 Hz response out of his filter. The one you linked to rolls the tweeter off at about 2300 Hz third order You'd end up with a big hole in the response.

19th January 2011, 12:47 AM	#7
lowpsiTSi diyAudio Member Join Date: Dec 2010	Ok that makes sense. I will have to find a tweeter with a lower frequency response.

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