Zaph's Latest!

[bobhowell]

docrw,

I have read of many instances were a crossover component or driver was hooked up wrong or bad. I would focus on that for your problem. Zaph has published a lot of designs and numerous people have built, just this one, BAMTM, with great results. This design has been out there for 2-3yrs and a lot of people are delighted with it, me included.
I think you have a bad component, but I am clueless about how to track it down. Ask around on the speaker forums and you will get help. Maybe someone lives near you.

Good luck

Bob

[docrw]

All the drivers are showing 7 to 8 ohms, which I thought would be the case since both speakers sound the same.
Question: on these Xovers does it matter where in the line the component is attached or is it just that all the intended component are on the same line. In other words when you look at a Xover schematic it shows the order but if all the components on a driver set touched at one point would it be the same?
Also I've never done a RTA session before but would like to. Can someone walk me thru it please. Maybe this will tell us if I have a problem at all...

Originally posted by MisterTwister
docrw, can you measure impedance of each driver without crossover? one of the drivers may be defective.

[MisterTwister]

http://www.claudionegro.com/
very nice step by step tutorial

[docrw]

I had a thought yesterday that maybe I should mention. I lined the backs/bottom/and sides of the cabs with some of that rubberized aluminum coated self stick sheeting that is used in car audio to quiet noise rattles and vibrations of subwoofers and wondered if the proximity of this aluminum and the coils proximity could be creating the problem with the sound of the speakers? Any thoughts? {see picture}
Maybe to the people who have built and or heard these, give me an idea as to what speakers you've used as a reference to these, so I can see what level you're coming from as a comparison.
David

[kristleifur]

Hey docrw, maybe you can measure the crossover networks directly.

You should be able to connect the woofer or tweeter network as a "tape loop" to your computer's sound card, and then play some sort of white noise or impulse through it and use measurement software to figure out if the crossovers do what they're supposed to be doing.

I've measured some tiny unlabeled surface-mount capacitors this way. Worked pretty nicely. Is it the best method? Don't know, it depends on if you're a software kinda guy or not.

[docrw]

Well, I spend my life at a computer and fairly good with them and some software, but this kinda thing is pretty much over my head. Believe me when I say electronics is NOT my forte, so I wouldn't even know where to begin, I've been asked to do the RTA thing which is over my head and realize this stuff all takes time to learn and conquer. I've been spending a ton of time lately just reading and trying to grasp the whole network thing and how different parts work off of each other, and to be honest it will be a while before I get it. I've been interested in speaker building for 20 years but never got this far into it, until now. Maybe you could expound further with this and explain what and how you're doing so we all can learn.
Thanks
David

Originally posted by kristleifur
Hey docrw, maybe you can measure the crossover networks directly.

You should be able to connect the woofer or tweeter network as a "tape loop" to your computer's sound card, and then play some sort of white noise or impulse through it and use measurement software to figure out if the crossovers do what they're supposed to be doing.

I've measured some tiny unlabeled surface-mount capacitors this way. Worked pretty nicely. Is it the best method? Don't know, it depends on if you're a software kinda guy or not.

[kristleifur]

Originally posted by docrw
Maybe you could expound further with this and explain what and how you're doing so we all can learn.

Welll I really wish I could give you anything concrete ... my thinking is that the crossover works in relation to the impedance of the speakers, cutting highs or lows as wanted. The idea is to swap out the speaker drivers for your soundcard input ... cut up a minijack-to-minijack cable if you can spare one, put the woofer crossover on the L channel and the tweeter crossover on the R channel. Then play back some white noise and record it, and look at the frequency analysis for each channel. The curves should probably look like they fiit approximately to each other - I guess!

Then you could go into some mathematical stuff and calculate what the filter slopes should like with the sound card impedance instead of the driver impedance ... but I'm just guessing based on some very simple methods I've used in the past.

If you've got a Mac, I think that FuzzMeasure Pro is probably a good tool to do this. Don't know any other software ...

I hope this helps rather than confuses Again, I must say I'm only thinking out loud

[critofur]

I measured my BAMTMs and they have a very flat frequency response - I think they're just missing bass, because I built the smaller sealed cabinet versions. They don't really sound "shrill" or "harsh" but they do sound a little weak on the low end which causes them to sound like they have too much treble. I would like to see how they sound with a good pair of subwoofers under them. I got two of these: http://cgi.ebay.com/PEERLESS-XLS-830...250379237373QQ and two of these: http://www.madisound.com/catalog/pro...oducts_id=1705 to try in various configurations...

When I said I don't like B&W speakers what I mean is: the treble sounds a little "hot" to me and I soon get a headache when listening to them, don't find them enjoyable for even a few minutes.

FYI, some speakers I DID like listening to were the Madrigal Revel Salon Ultimas. Good solid bass, nice detailed midrange, and crystal clear sparkling treble which didn't cause any strain and pain to my ears - even sounded good listening to that twangy metalic plucked guitar on the 2nd (or 3rd?) track off album "Rumors": http://www.amazon.com/Rumours-Fleetw.../dp/B000002KGT

Ah, track # 3. "Never Going Back Again" - that song is beautiful, on speakers that have a fine top end.