Earlier this year I listened to this:
http://http://www.forsman.no/DW1/Produkter_VSS5.html
Which has dipole B&Gs down to about 370 Hz, and hornloaded horisontaly (but not vertically)
I really liked the sound so I hope that Beyma TPL 150H (or with a diy-horisontal hornload) should give similar results. I do believe that that TPL 150 might have less vertical dispersion compared to the B&G, but on the other hand; the tweeter-B&G in the Forsman-construction is HP at 10.000 Hz, meaning that the B&G 8 that is also used, is used up to this point. (The B&G 8 I assume has no better vertical dispersion than the Beyma - possibly worse)
Thanks for all replies! 🙂
http://http://www.forsman.no/DW1/Produkter_VSS5.html
Which has dipole B&Gs down to about 370 Hz, and hornloaded horisontaly (but not vertically)
I really liked the sound so I hope that Beyma TPL 150H (or with a diy-horisontal hornload) should give similar results. I do believe that that TPL 150 might have less vertical dispersion compared to the B&G, but on the other hand; the tweeter-B&G in the Forsman-construction is HP at 10.000 Hz, meaning that the B&G 8 that is also used, is used up to this point. (The B&G 8 I assume has no better vertical dispersion than the Beyma - possibly worse)
Thanks for all replies! 🙂
Yes - neo8 is worse in the vertical plane that TPL150. I know, I have tested it.
What really separated the Neo3 and 8 from good AMT's is the dynamics. As Linkwitz have shown, the Neo drivers have serious dynamic compression problems, even at moderate input levels.
If you are to hornload a dipole, you must do it both front at rear to maintain a good dipole pattern (should be symmetric front/rear). I've seen dipole prototypes (with AMT also) with waveguide only on the front side. In my opinion a bad idea.
What really separated the Neo3 and 8 from good AMT's is the dynamics. As Linkwitz have shown, the Neo drivers have serious dynamic compression problems, even at moderate input levels.
If you are to hornload a dipole, you must do it both front at rear to maintain a good dipole pattern (should be symmetric front/rear). I've seen dipole prototypes (with AMT also) with waveguide only on the front side. In my opinion a bad idea.
I tried to find this on my own at the Linkwitz site using the site map - but I had no success. I would like to know more about this topic regarding the Neos' and if it is not to much of a bother would appreciate if you could point me to this information.
I currently use ESS AMT1's but I need to replace them with something that is magnetically shielded due the the wife having a pacemaker device for her heart and she needs to avoid strong magnetic fields.
TIA
Virtually all modern AMT's use Neodymium magnets, so the stray field is low.
I tried to find Linkwitz' measurements also, I have seen them - and they have been referenced in a thread here. Will search!
I tried to find Linkwitz' measurements also, I have seen them - and they have been referenced in a thread here. Will search!
He does abuse the little driver quite badly, doesn't he? He's squeezing up to about 108 dB's out of the poor thing. But agreed, the Neo3W probably isn't suited to low crossovers and high power levels.
Agree - his test is tough, but it shows that there are problems. I have fried a couple of Neo3's, so I know they dont have great power handling.
Thanks Stig!!
BTW - I luv this thread and your work. Thank you for sharing your knowledge and experience with this project - esp the discovery of running the speakers "nude" (without baffle).
BTW - I luv this thread and your work. Thank you for sharing your knowledge and experience with this project - esp the discovery of running the speakers "nude" (without baffle).
The Forsman VSS5 uses Neo10s. The 10kHz cross to the Neo3 makes me suspect first order, in which case the vertical dispersion's probably reasonably wide---perhaps around 30 degrees at the usual -6dB definition.
Arguably the problem is putting 260W peak into a driver rated for 50W peak, but there's a thread about that with Linkwitz's own remarks on the matter. Mostly I'm just amused by the description of 108dB as a moderate level for home audio. On a tweeter of all things. 😱
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Its not 260W.... As Sigfried says:
"The driver terminal voltage is set to 30 Vpp. The signal shape is the same as that of a 100% amplitude-modulated sinewave, where the carrier is at 1.5 kHz and the modulation frequency is 150 Hz. For 100% AM we can derive Vrms = 0.22 Vpp. Thus the 30 Vpp amplitude corresponds to 6.5 Vrms, which would deliver 5.3 W into 8 ohm. A 60 W amplifier, as used for the ORION tweeters, could apply 60 Vpp max to the driver terminals. I have certainly measured 30 Vpp during loud passages. ".
Since the Neo3 is 3 ohm the power dissipation is higher, but nowhere near 50W.
Its also interesting to see that a relatively cheap Seas dome tweeter is far far better in this respect than the Neo3.
"The driver terminal voltage is set to 30 Vpp. The signal shape is the same as that of a 100% amplitude-modulated sinewave, where the carrier is at 1.5 kHz and the modulation frequency is 150 Hz. For 100% AM we can derive Vrms = 0.22 Vpp. Thus the 30 Vpp amplitude corresponds to 6.5 Vrms, which would deliver 5.3 W into 8 ohm. A 60 W amplifier, as used for the ORION tweeters, could apply 60 Vpp max to the driver terminals. I have certainly measured 30 Vpp during loud passages. ".
Since the Neo3 is 3 ohm the power dissipation is higher, but nowhere near 50W.
Its also interesting to see that a relatively cheap Seas dome tweeter is far far better in this respect than the Neo3.
Perhaps part of the comparison regarding the dynamics between the B&G and true AMT's is that the B&G's are magnetic planar type structures and use a flat diaphragm (similar to small electrostatic speaker) rather than a folded diaphragm per Dr. Heil's patent. A true AMT diaphragm moves a lot more air volume than flat one - 5 times more according to the patent(s).
Considering this I might need to dismiss the B&G's from my list. OTOH my intention is to use them above 7kHz as tweeters - so perhaps not such a big deal. For their relatively low cost I should get a couple and see if they will get the job done in a 3-way design + sub-woofer.
My bad; missed a factor of two. 🙁 64W.
It seems expected that a dome tweeter would handle more power more gracefully than a small planar since one has a suspension and the other doesn't. Am I missing something interesting here?
It seems expected that a dome tweeter would handle more power more gracefully than a small planar since one has a suspension and the other doesn't. Am I missing something interesting here?
64W ??
30Vpp is approx 10.6V RMS, which is 35W into 3.2 ohms . Now remember that Linkwitz' burst signal is modulated, so the RMS power of the entire burst is lower than that.
I dont think the problem is lack of suspension. The problem is that the "coil" (ribbon) is heating up very quickly, creating power compression loss.
30Vpp is approx 10.6V RMS, which is 35W into 3.2 ohms . Now remember that Linkwitz' burst signal is modulated, so the RMS power of the entire burst is lower than that.
I dont think the problem is lack of suspension. The problem is that the "coil" (ribbon) is heating up very quickly, creating power compression loss.
64W peak, yes; 15V^2 / 3.5 ohms, which is Linkwitz' peak voltage divided by the resistance speced in BG's Neo3 datasheets and whitepaper. Still operation outside of BG's 50W peak spec if the actual impedance is 3.2 ohms, though I'm kinda curious where 3.2comes from. That said, in my experience power ratings are pretty fuzzy so it's possible BG meant 50W RMS peak. That would be an odd definition of peak, though, and 30-35W is still comfortably above the Neo3's sustained rating of 10W RMS (the only place I've seen an actual spec on the duration of peak loading is on certain milspec power resistors). Not sure the details are particularly important; in end it seems unsurprising the Neo3 shows strain in Linkwitz's test.
An easy way to check for thermal compression would be to look through one of the Neo3's holes with an imaging thermometer with the driver under load. I have Neo3s, but not the thermometer. Certainly a reasonable hypothesis; the 25TFFC dissipates less power due to its greater impedance and its voice coil's probably better ventilated than the Neo3 ribbon due to higher airflow in the 25TFFC's gap.
An easy way to check for thermal compression would be to look through one of the Neo3's holes with an imaging thermometer with the driver under load. I have Neo3s, but not the thermometer. Certainly a reasonable hypothesis; the 25TFFC dissipates less power due to its greater impedance and its voice coil's probably better ventilated than the Neo3 ribbon due to higher airflow in the 25TFFC's gap.
So in short - the cheap Seas dome has greater power handling...
I've measured the impedance of the Neo3's I have here, its 3.2 ohms. That's how they get that nice 90 dB+ sensitivity...
I'd like to add that I like the Neo3 a lot. It sounds great when used within its limitations.
I've measured the impedance of the Neo3's I have here, its 3.2 ohms. That's how they get that nice 90 dB+ sensitivity...
I'd like to add that I like the Neo3 a lot. It sounds great when used within its limitations.
As the 25TFFC is rated for 80W RMS and the Neo3 for 10W RMS that's kind of how I'd hope things would turn out. 😛
I quite like the Neo3 as well. Still haven't figured out a way to cross it satisfactorily in the 1.4-1.5kHz range so I wouldn't say it's an Orion candidate even at lower SPLs. Measurements say an LR6 cross ought to be OK down to 1.3kHz at my definition of moderate levels (~60dB RMS) but it doesn't sound good and I can't figure out why. I have had good success crossing at 1.8kHz and, now that the drivers are broken in and I've found some equalization improvements, might be able to bring that down to 1.6kHz.
I quite like the Neo3 as well. Still haven't figured out a way to cross it satisfactorily in the 1.4-1.5kHz range so I wouldn't say it's an Orion candidate even at lower SPLs. Measurements say an LR6 cross ought to be OK down to 1.3kHz at my definition of moderate levels (~60dB RMS) but it doesn't sound good and I can't figure out why. I have had good success crossing at 1.8kHz and, now that the drivers are broken in and I've found some equalization improvements, might be able to bring that down to 1.6kHz.
starting setup for no baffle DSP crossover/amp
Hi
Please does anybody have som starting /theoretical values for my DSP/amp (hypex 2.100).
I plan to use:
Beyma G550 (18") for woofer
Scan Speak 18w8545 for mids
Tang Band w4-1320 for highs for now
It will be no baffle, and lowest frequencie should be around 30 to 40 hz.
Apart from standard 3 way filtering ( 6db, 12db, or more...), I guess I will have to put in som boost for the woffer and mid, and a notch filter for the dipol peak for woofer and mid but how do I calculate the theoretical values as for now I don't have any measuring equipment.
Please is there anybody who can give me some advise.
Thanks alot
Uwe
Hi
Please does anybody have som starting /theoretical values for my DSP/amp (hypex 2.100).
I plan to use:
Beyma G550 (18") for woofer
Scan Speak 18w8545 for mids
Tang Band w4-1320 for highs for now
It will be no baffle, and lowest frequencie should be around 30 to 40 hz.
Apart from standard 3 way filtering ( 6db, 12db, or more...), I guess I will have to put in som boost for the woffer and mid, and a notch filter for the dipol peak for woofer and mid but how do I calculate the theoretical values as for now I don't have any measuring equipment.
Please is there anybody who can give me some advise.
Thanks alot
Uwe
My first advice is to build a baffle for that 18". You wont be able to hit 30 Hz without a baffle. If you can live with 50 Hz, then it should be ok to run it nude I guess.
Suggested XO: 400, 1200 Hz
If you XO there, all you need for the mid is a 6 dB hi-pass, since you will be below the dipole peak all the way.
A nude 18" woofer will have its dipole peak around 500 Hz, so it should be quite easy to EQ. Use a 6 dB shelf from around 50 Hz as a starter. You might want to add a little broad peak around 35-40 Hz to boost the low end, as this is usually required to get a natural sounding balance in my opinion. It might also be required to drop it a little before the dipole peak, around 3-400 Hz.
I dont know the 3" TB, so I dont know... anyway, it should work from 1200 without much dipole compensation? Only real measurements will tell.
Suggested XO: 400, 1200 Hz
If you XO there, all you need for the mid is a 6 dB hi-pass, since you will be below the dipole peak all the way.
A nude 18" woofer will have its dipole peak around 500 Hz, so it should be quite easy to EQ. Use a 6 dB shelf from around 50 Hz as a starter. You might want to add a little broad peak around 35-40 Hz to boost the low end, as this is usually required to get a natural sounding balance in my opinion. It might also be required to drop it a little before the dipole peak, around 3-400 Hz.
I dont know the 3" TB, so I dont know... anyway, it should work from 1200 without much dipole compensation? Only real measurements will tell.