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I have the Tympani IV not 'a'.
What would you consider the minimum number of Neo 8's for this configuration?
Maggies Tympani IV's
You should really go for 6 per side for the TIV.
That allows for fuller cancellation of the 12khz resonance peak to 2db above average midrange output, and flattens out the freq response. Trying 4 per side did not do it, and the bottom end of the line array did not extend as far down and would bottom out at peaks at loud playback - below my max threshold. You can crossover below 300hz with the 6 per side, 500 hz for the 4 per side. I would not suggest 4 er side unless you have a DEQX or similar unit and can use it to EQ and cut off the driver array steeply without introducing phase problems.
If you were building a new mid/tweeter frame then I would suggest using 8 or 9 drivers er side. That allows you to stretch the XO down to 200hz without the line ever bottoming out. That was the reasoning for the number of drivers in the LS9 design, though Richie kept the XO rather higher than what was possible. This also eradicates any left overs from the resonance peak to make for a flat top end to the array output.
Satie and I get good results with 6 per side, and that fits in the original midrange panel slot in the T-IVs.
I think the frequency response becomes problematic if you go with a smaller number, and you may have to go with a higher crossover frequency between the bass panels and the NEO-8s.
I made a very nice center channel speaking using the Neo3-PDRW and a Vifa 7" woofer.
The crossover was 2nd Order @ 2000 Hz. Works well at the moderate volumes I need.
I love the music of Dmitri Shostakovich
My favorite drivers are back.
Ding PoisonM Your friend can build a Neo8 line array and use the MG20.7 bass driver and tweeter with a new separate frame for the Neo8 and tweeter. The Neo8 array has serious power handling ability and is far more sensitive. The array (with sufficient baffle) can play to 200 hz quite loudly without bottoming out or burning.
Soooo, I'm thinking I should take advantage of this, before they go away again! :-))
Satie, if I used 2x parallel connections of 3 in series ... I end up with a 6ohm mid driver ... which is about 1200mm (4') long.
Re. XO configuration, based on your experiences with these drivers:
Q1: Do you still recommend only a 6dB HP filter for these Neo8 mids? So they roll off naturally at the top end - which would result in something like:
- bass LP 18dB @ 300Hz
- mid HP 6dB @ 500Hz
- ribbon HP 6dB @ 4KHz?
Q2: Or should I continue with a mid LP (like on my T-IVa mids) when crossing over to the ribbon? Which would result in something like:
- bass LP 18dB @ 300Hz
- mid HP 6dB @ 500Hz
- mid LP 6dB @ 3800Hz
- ribbon HP 6dB @ 4KHz?
Thanks,
Andy
OK
Two things. First is how much baffle are you going to provide them, as you can see in the spec/info sheet (I didn't look to see if they put them back online) baffle loading changes the FR in the sub 1khz range.
Second is how loud you play, the louder you play - the drivers will bottom out at a higher freq. At 126db it bottomed out at 800hz or so with the lower mid going from weak to MIA..At 100 db you are flat to below 300 db and bottom out about 250 hz. Playing to 110 db you will have a slightly weak lower mids but I don't have a solid -3db point for you - I would guestimate that an array of 6 with ample baffle on one side will go to 500hz at 110 db (if you care)
.
The more drivers in the array the lower the freq at which they are usefully additive and the smaller is the gap resonance peak at 11-12 khz. There are still traces of it at 6 per side, none at 9 per side. I should point out that though on axis the FR will roll off at 14 khz with the regular Neo8, the off axis FR of the array will drop off earlier - 3db @ 11-12khz at less that 30 deg off axis. .The PDR version will get to > 14khz off axis (well at a reasonable angle) and will ony droop on axis to -3 to 5 db at 20 khz
My solution is to cut off at 150 hz 6db and stretch the bass LP up to 250 hz LR4 or 200 hz B3. That way there is hardly any phase on the driver and I can plug in the ribbon tweeter at the 18khz 1st order (still shares the 150hz HP so is not really exposed to very low freq)
I starte out with B3 symmetrical and equidistant drivers at 300 ant 6khz. I didn't have a head in a vice problem but having measured the off axis FR I wanted to stay out of trouble on the dispersion side. So I pretty much did the same with symmetrical LR4.
I then experimented with letting the driver array play full range (hence my knowledge of when it bottoms out) and just added in the tweeter and bass with B3 and LR4 at various freq between 6 and 12 khz. Never got it to mesh perfectly.
The compromise solution was to go linear phase for the entire speaker, so 1st order symmetrical at 250 hz and appx 8 khz avoided the head in a vice most of the time and had the most perfect imaging I ever heard. Of course with an equidistant arrangement of all the drivers. I think that would be the place to start. You would then only bottom out the mid array at 300hz when playing 110 db peaks (since you are sitting closer - I measured at 3m) It is not bothersome since the bass panels are only 1st order in this setup and fill out the missing bits 250-500 hz perfectly adequately on 110 db peaks.
I experimented with myriad other XOs for different placements. Ask and I will answer if you have anything in particular in mind.
In your version Q1 you have no mid LP - If your drivers are equidistant then you can LP at the same freq as the tweeter. 4 khz is still marginally too low for the ribbon to operate with a 6 db HP, so I would take it up till you have the beginning of dispersion problems - likely 6-8khz. Otherwise the ribbon will show you its displeasure at being driven hard with a metallic sheen to everything. You can try doing the Bass LP at 1st order instead of 3rd and experiment with lowering the LP to 150hz if it is not interfering with .clarity. If the bass' intrusion into the 300 hz bothers you then do cut it off at B3 at 300hz - or even lower. Just that you will no longer be able to have time alignment and you will need to get it in phase carefully according to how your drivers are offset from equidistant.
In Q2 I am guessing that you are offsetting the XO from symmetrical -3db freq to compensate for offsets from equidistant driver placement. If that is not the case the mid-tweeter should XO symmetrically, and up to an octave higher, And the bass LP freq should be matched to get you in phase and compensate for offset.
Go by ear if you have a variable XO and then measure.
If your listening levels are more civilized then you can crossover the tweeter lower and take it to as low as 4khz so long as it has another HP before it in the 100-500 hz range. If you can set it up to share the mid HP then that will simplify it somewhat,
Lots of options
Thanks very much for the detailed response, Satie.
I have a lot to think about but I thought I would post a pic of my L channel 2 panels - and give you baffle measurements.
I'll respond to your other comments, later.
The flash kind-of 'sees through' my sock material - but at least you can see the drivers clearly.
Re. the baffle arrangements for the Neo8s - they will replace my T-IVa mid panels. The mid/ribbon frame is 10" wide - so there's:
* about 5" of baffle on the outside of the mid panel, and
* at least 17" of baffle on the inside - given the mid/ribbon frame is butted up against the bass frame.
Which I would've thought is more than adequate?
Regards,
Andy
Looks like plenty of baffle to me, Andy.
I think you are going to love the results if you go with the NEO8 arrays.
There are so many viable configurations with these drivers. I ended up with symmetric XOs at 260Hz and 3KHz, 48db/oct throiugh the DEQX and a 40Hz LR4 hand-off to a sub. That way no driver is close to breaking a sweat no matter the volume level.
Please keep us in the loop as you do this project.
Awesome frames, BTW.
The single sided baffle should be sufficient.
Guitar slim, Though I never used 48db filters, I did use LR4 and the tweeter was definitely stressed at my play levels at 4 khz, not to speak of 3khz. The compromise was 5 khz LR4 or B3. The tweeter does not have that much of an advantage over the Neo8 mids at 5khz and below. The Neo's dispersion is still pretty good at 5khz and detail retrieval is pretty much on par at these freq. Cohesion wise I liked keeping the low treble with the mids on the same driver.
Hi Satie! Thanks for your thoughts.
I never noticed any limitations of the ribbon with the steep slope at 3KHz, but then it's possible I don't listen as loud as you.
Maybe next time I'm playing with the DEQX I'll try raising the mid/tweeter crossover frequency.
Some time ago I had to replace a ribbon and went a month or so running the NEO8 arrays as mid/tweeters and was surprised how dramatic the difference with not having the ribbon "sparkle". Maybe not surprising.
Anyway I expect 5KHz is a good choice.
.
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
The B-G drivers have quite low distortion, compared to other ribbon and planar drivers of similar size. They are a well engineered product. It's good to see them back. Anyone know why they disappeared?
A non audio company bought them from the founder's estate and was trying strong arm OEM marketing techniques that blew in their face. As part of the scheme they took the drivers off the DIY market.
What are the differences between the PDR and non-PDR versions of the NEO 8? Both are dipoles, correct?
The PDR version has a damping layer in it that acts as an acoustic lens and provides better dispersion at higher freq. You can make a line array of Neo8 PDR and not use a tweeter. The PDR version does not play as low as the regular Neo8 and has more limited power handling and 1+ db lower sensitivity. So for use in a line array you would need a line of 8 or 9 to obtain similar extension at the low end as you get from a line of 6 regular drivers (appx down to 200 hz.but 250hz -3db point.)
Is it safe to assume that any amplifier which 'comfortably' drives a Tympani IV/IV-A MR + ribbon tweeter wouldn't be phased (pun intended!) when it confronts the MR and array of nine Neo8s?
Edits: 06/02/16
Pretty safe, I think. You can wire the NEOs in a series/parallel arrangement to produce a reasonably easy to drive load. And the NEOs are more efficient, so power should not be a problem.
You may find the NEOs somewhat more revealing, so whatever character the amp has may be more apparent.
Great, thanks Satie. Non-PDR it is! Is Parts Express the place to buy them (as soon as they actually get some, and I have the dough!), or is there a better source? And is the new production quality the same as the old, if anyone yet knows?
Edits: 05/30/16
I had a chance to speak to someone from Parts Express today at THE Show, and he told me that they will now be the exclusive American dealer for the BG drivers. He also said they were probably going to add a few more to the three they're now carrying, but wasn't sure which ones. Neo-8 PDR and Neo-8 S, perhaps? The RD series drivers, however, will no longer be available.
Edits: 06/03/16 06/03/16
Hey man
Anything particularly impressive at the show? That is other than price tags?
LOL, yes, I've seen some very interesting stuff, including some remarkably tiny base traps from Synergistic Research and at least 370 degrees of stable surround from two channel. Would love to write about it now but meeting a group for breakfast so it will have to be tonight. I'm planning to post the planar news here including Magnepan's demo (3 channels using the Bryston-Magnepan processor, very holographic) but it took too long to get the photos transferred from my phone last night to get anything up.
Were there any DEQX type time corrected systems on demo?
Hmmm thought I'd answered this from my phone during lunch but I guess it didn't go through!
Anyway, the answer is yes. they Kyron dynamic dipoles are tri-amped with DEQX. Great imaging.
Unfortunately, DEQX wasn't demoing with Maggies this year -- they did that last year. They had an impressive demo of a cheap, awful sounding $20 horn -- the transformation with DEQX is stunning. But of course that's just a show gimmick for demo purposes. They were demoing with custom speakers, but I didn't really get a chance to listen to that demo for various reasons. However, I spent some time talking to Alan Langford, their general manager, and he was kind enough to answer a range of questions about setup with Maggies.
First of all, he said that they already have curves for many Maggie models, so no driver calibration is necessary. I told him that I was doing a custom build with Neo 8's, and asked about the procedure for doing calibration yourself. He said that with dipoles, the calibration has to be done in a very large space to avoid backwave reflections -- outdoors, or in a large space like a gymnasium. He recommends that the measurements be made from 3 meters, so that relative driver timing is representative of what it will be at the listening position.
Alan also said that the early models will daisy chain with the newer ones, so it's possible e.g. to use an old model for a subwoofer. Apparently, the older models are starting to show up at very attractive prices. He said that Larry, their dealer in Denver, maintains some used stock and is the expert on what is available. An early model could go for as little as $1000.
He said they've also started using an audio player from Roon Labs -- which I saw elsewhere in the show -- rather than JRiver. It streams directly to the current units (as does JRiver).
I asked about the backwave and he said that it's corrected with parametric room EQ, using the DEQX's IIR filters.
Do you think a room stuffed with mattresses pillows and comforters or whatever absorptive stuff is available behind the speakers could substitute for open air or an anechoic chamber for the speaker measurements?
We should ask Guitar Slim and Helmholz how they did their speaker measurements.
I must say there is nothing to pick at in the Kyron speaker-amp-processor package but for the hefty 6 digit price for the "small" kronos model .
I don't know how well it all works together but it looks very promising.I particularly like how they figured to support the drivers by their magnets to reduce resonances. Also the CLD metal frame shows both attention to detail and colossal overkill with Ayre like slabs of Al.
I was wondering if the DEQX corrected speakers managed to outdo unprocessed linear phase time aligned systems you heard before in imaging soundstage and detail.
I can tell you that the imaging on the Kyron was very impressive -- good enough that I made a note about its great imaging (my senile brain being what it is these days, I jotted down some of the high points so I could report back). But it's hard to compare it to other time-aligned systems, given variable show conditions, recordings, speaker placement, etc. I don't remember being blown away by detail, but that is presumably a function of the dynamnic drivers rather than the DEQX.
I did notice, consistently, that dipoles made the best images. They were pretty much the only images in which I had a real sense of localization. Many of the dynamics put the images all over the place -- up, down, sideways. Of course there wre a lot of crap recordings, I asked them to play an orchestral recording when I could but in many cases that wasn't possible and I had to listen to awful multimiked recordings with a singer about 80 dB louder than Caruso.
Seems to me I had a discussion with Helmholz about his measurement techniques a couple of years ago, you might be able to find it here. Stuffing the room might be adequate for higher frequencies, but it wouldn't get the low. In fact, IIRC, Alan Langford said that even an anechoic chamber can be inadequate for this purpose, since they aren't anechoic at low frequencies. And unfortunately gated measurements don't really work.
I was pleased overall with the sound of the Kyron but of course show conditions don't really allow one to hear the system at its best. It seemed promising (except for the price tag). By and large, I was impressed by the point source dipoles, they really did almost as well as the line sources in conveying a sense of space. But more later, have to leave for the show.
I guess that leaves you with just the option of taking the speaker out to the driveway on a clear day without wind and measuring there. Perhaps at the open garage door with the backwave facing out.
I too never found point sources to image as well as the line sources So once I heard my firt Tympani speaker in 1982 it confirmed my suspicion from hearing the CLS earlier that something is fundamentally wrong with point source speakers. I presumed it was the multiple drivers in a 3 way not being time aligned and theory from the brit hifi press that it relates to crossover order not preserving phase. So I went with a vandersteen 2C when I had the chance and it did a great job on imaging but for a somewhat random height distribution for instruments from the general plane of the orchestra. It also lacked detail relative to what I remembered from the CLS and Quad 57.
Then I discovered Apogees and that told me that it is the drivers and the line source geometry. They were nearly as resolving as the ESLs and had all the imaging characteristics of the Tympani I heard before just with obviously more detail. I could not imagine why anyone who could afford them would prefer taking an expensive box home. Nothing else produced that kind of realistic imaging and holographic soundstage and still reveal so much detail. Not the big Vandersteens in the same room, not the Thiels at the competing dealer, not the B&W (which compared badly to the Thiels because the B&W were not time aligned)
I was actually impressed by the imaging of the point source dipoles I heard at Newport. Not the equal of a line source, no, but significantly better than almost all of the boxes I heard. The boxes did depth and spread, yes, but for the most part they didn't give the palpable "it's out there" imaging that the dipoles did. Of course, this was under show conditions.
Madisound is another source that used to carry them. I only bought from them two pairs on a discount opportunity. Otherwise I bought from PE.
They had some inventory recently (last week), I don't know if any are left at this point.
Are there any companies out there with old stock of BG speakers? I'd like to find the BG Radia 220i or 220DX center channel.
P.S. Is the 220DX the same as the 220, but with aluminum? Or is the 220 something completely different (older?).
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