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Multi-Way Conventional loudspeakers with crossovers

Problems with Scanspeak Illuminator 12MU/8731
Problems with Scanspeak Illuminator 12MU/8731
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Old 10th November 2015, 09:27 PM   #51
Mercury3 is offline Mercury3  United States
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Not finished but I have an update to this. Sorry I don't have all the measurements yet but I've spend countless hours using my ears which are I think very valid. I'm a novice when it comes to speaker building but I'm 60 and been an avid audiophile since very early 20's. I've owned a lot of good speakers over the years from Acoustat 2+2's to B&W 801's etc.

I need to apologize to those who were telling me it's in the crossover. It is although I think I have two additional issues which made more difficult my analysis of this.

Some of my experiments were made in hast due to time constraints and I encountered what I think is another problem which masked the first.

I hzve two of the Pass Labs xvr-1 crossover units. I had an old one and also bought a new one last summer. Very expensive so I refused to believe it could be from the crossover. I bought two Bryston (10b std and 10B-Sub) to compare. No change they had the same issue.

I'm scratching my head about how or why but I have to be hearing crossover ringing but only through the midrange drivers. I can't use even a 6db med Q setting without hearing it just a little. The more poles I add the worse the anomaly becomes. However I can get rid of it when I use the 6db settings with Low Q. It's gone on that setting.

However then when I turn it up I'm hearing a different sounding anomaly which I "think" is the peak up around 4.5 to 5.5 K. Thus I need a steeper setting. Also 6db is not steep enough to keep lows from over driving the units at high levels either. I think I'm starting to exceed xmax when I play it loud.

My thoughts are most likely going to be to put a simple 6db band pass filter on the midrange units at approx. 300hz and 2.5K and use the 6db active settings at the same. 290hz and 2.5k which will give me my desired 2nd order.

I'm really not understanding why I'm having this trouble. My prior midrange was the focal 5k4411 which I had no problems with. None and it was a good sounding midrange. Wishing I had just kept it.

Anyway I've made some mistakes in this design. Live and learn I guess. If I can't resolve it with the ScanSpeaks soon I'm going to try the Eton 4 inchers Madisound has on sale right now. It's almost an exact fit and looks like it has twice the Xmax.

I'm wondering if some of this trouble is the ScanSpeaks underhung coil with limited Xmax issues amplified by the fact I chose to use two of them and like to play fairly loudly at times.
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Old 10th November 2015, 10:06 PM   #52
eriksquires is offline eriksquires  United States
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While you are experimenting, I would not bother trying a hybrid approach. Do a 12 db/octave on the active unit and measure the results. My guess is that you'll find significant ringing left over. Compensate for that with a resonant filter. If you go hybrid, use a Zobel filter to help smooth out your response, and then you will have an easier time with cutting out the ringing in the high frequency. Once you have figured out how to get a nice smooth upper end decide on whether to use an active or hybrid approach.
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Old 10th November 2015, 11:57 PM   #53
Face is offline Face  United States
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Quote:
Originally Posted by Mercury3 View Post
Not finished but I have an update to this. Sorry I don't have all the measurements yet but I've spend countless hours using my ears which are I think very valid.
Not trying to be snarky, but this is what is taking you so long to dial them in.
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Old 1st March 2016, 07:31 PM   #54
Mercury3 is offline Mercury3  United States
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Default <<Updated>>

I know some will be disappointed but I gave up on using the two 12MU's. I don't know what the hell. I played for many many hours with the omnimic. Distortion and other measurements I got were all very similar to what I found for that driver on the internet. Nothing bad showed up.

I have one theory and again it's only a guess. I play my music loud at times. The anomaly I was trying to solve only showed up at fairly loud volume. To me not to loud but kind of loud. Turn it down a little an the anomaly disappeared. The 12MU only has 3.5mm Xmax. Possibly I was pushing Xmax at higher volume?? I don't know.

I switched to a single 18WU/4741T and everything is solved. It sound VERY good. Seriously I'm happy with them and can live with them.

Pictures below but please no making fun of my cabinets. I'm not much of a wood worker but they are nice and solid with bracing and what not.

If anyone lives near the north Denver area I'll give you a FREE pair of 12MU's as thank you for the help people tried to provide for me here. The other pair I'm going to use for a smaller system I'm gonna build for the tv down in the family room. The drivers are perfectly fine I didn't damage them in any way or anything. Again free if anyone is close enough to come and get. I can't ship them because I didn't save the boxes.

Mark

P.S. - The equalizers are only on the woofer sections.
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Old 1st March 2016, 07:44 PM   #55
Mercury3 is offline Mercury3  United States
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Thumbs up Pass Labs XA-30.8

I thought I'd give a quick plug for these new amps from Pass Labs. Conservatively I'd say I've owned more than 20 high end power amps over the last two years. Some of them 100 lb plus monsters. Prior to now, my favorite amp excluding Bass was an Audio Research Reference 110. It had a sweet midrange that was hard to beat.

The XA-30.8 is heads above every other power amp I've ever owned. I'm running it above 300hz on the ScanSpeak 18MU midrange and D3004/6640 Beryllium tweeters crossed over at 2500 hz.

Last night I cranked the hell out of I-Robot by Alan Parson's project. They hit hard yet the needle didn't even inch up.

This Power Amp is a keeper.
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Old 1st March 2016, 09:29 PM   #56
eriksquires is offline eriksquires  United States
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Mercury, remind me please. Did you attempt the 12MUs in a sealed or ported cabinet?

Best,


Erik
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Old 1st March 2016, 09:47 PM   #57
Mercury3 is offline Mercury3  United States
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Originally Posted by eriksquires View Post
Mercury, remind me please. Did you attempt the 12MUs in a sealed or ported cabinet?

Best,


Erik
They were sealed but of rather large volume. I didn't think it mattered much as my crossover point was around 300hz give or take a little experimenting. (loosely stuffed with wool/fiberglass combination)

Last edited by Mercury3; 1st March 2016 at 09:48 PM. Reason: Added
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Old 16th May 2018, 02:00 AM   #58
miklos is offline miklos  Hungary
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So you never tried the 200uF caps ?
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Old 16th May 2018, 02:09 PM   #59
lowmass is offline lowmass  United States
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Mercury...

I would take your Omni Mic and do some CSD measurements on yor offending drivers AND the ones that sound ok just as a comparison. Run the drivers directly AND with the crossovers to compare.

I have seen drivers that have a similar issue to what you describe that showed no big issue in freq. response or distortion ( at moderate volume anyway) BUT that showed some obvious problems on CSD. Some problems are much easyer to see on CSD .

I would set up with mic about 1 inch away from driver diaphragm (at low volume) and in your case set the widow at about 5 ms. Take some measurements with mic directly at cone center, close to cone edge, and close to mid way between those two areas. Sometimes a cone can misbehave at a specific area and you can miss it if MIc is moved a bit. You are looking for a "tail" in the plot. This will be a section of the response that decays at a much longer time period than everything else and that section of the plot will look like a "tail".

Recently I was looking at a ribbon that had a similar issue that you discribe. Distortion was low and freq response was smooth but had a small wiggle at 4 khz that many would think is not bad. However looking at it with CSD we see a huge "tail" at 4k. Everywhere else on the plot was clean (decay to about nothing within about 2 ms) BUT at 4k it would "ring" out for about 6 ms.
When you said you could hear a sound similar when you hook up a battery that was a giveaway to me. This ribbon was the same. You could tap lightly on it and hear a metallic sound. It was a pourly damped resonance centered at 4 khz that rang forever BUT was only a small wiggle in freq response.
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Old 16th May 2018, 03:33 PM   #60
lowmass is offline lowmass  United States
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Ha what year is this?
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