Thoughts on Dayton Audio's higher end tweeters

[craigk]

How low will the RT4001 go?
Do you know how low the Neo3 PDR will go? (Don't know if I could live with it though, its ugly compared to the others )

The Neo has a faceplate you can get. The question is , do you want a pretty speaker or one that sounds great. You have to decide that.

[Wolf]

The spec sheet says 2kHz for the 4001, but that is likely a bit optimistic. Let's say it's possible. Paul used it with a 10uF and 0.35mH coil in the Spitfires, and a 10uF is not a small cap.

The Neo3PDR I have also used, and it is able to go down to 1.8kHz. It is however not easy to use. It is hard to get the line settled between sibilant and dull.

Another unit you should always consider in the 'ribbon' arena is the HiVi RT1.3 and its variant WE. However, I don't think it will quite go low enough for your supposed xover point. 2.5k is about as low as it should go.

Back to your midbass- Pete said it should take a damped 3rd order network to yield a 2nd order response, and they marry it to the RAAL in the Derecho. Speaking of which- you planning of slicing the cone?
I think you'll be able to get a bit higher than 2.3kHz. How much depends on your determination, but it should work to just shy of 3kHz if you so desire.

Later,
Wolf

[a4eaudio]

The Neo has a faceplate you can get. The question is , do you want a pretty speaker or one that sounds great. You have to decide that.

I get your point. While many people on the board would choose "sounds great" I'll put this right up there with Hoffman's Iron Law. There is a trade-off and I may take looks pretty and sounds almost great.

Back to your midbass- Pete said it should take a damped 3rd order network to yield a 2nd order response, and they marry it to the RAAL in the Derecho. Speaking of which- you planning of slicing the cone? I think you'll be able to get a bit higher than 2.3kHz. How much depends on your determination, but it should work to just shy of 3kHz if you so desire.

Yes, I had never seen that thread before and the comments this week about how well it turned out in the Derecho is what gave me my current idea. I was thinking all Dayton's would be cool for MWAF, but the tweeters just don't seem to work out for me. That's also why I don't simply use the Satori's I picked up, I'd like to mimic the Derecho a little but I'm not buying any RAALs.

What I'm trying to figure out is "what would be the best AMT/Ribbon/Planar tweeter (say under $130) to use with a sliced PM180-8 (let's assume a 2.8kHz xo rather than 2.3kHz) and two 10" woofers in a cabinet nearly the same size as the Derecho?"

[jhollander]

If the baffle was narrow enough with a big edge radius I might try the AMT3-4 alone.

[Wolf]

If you don't mind padding the 180 a smidge, then the RT1.3WE or RT4001 would get my vote from the above.

Since you are looking outside Dayton Audio, there are maybe a few others to consider;
- Beyma TPL75
- Bozhen CQ (which is a hybrid ribbon, well, sortof...
- Aurum Cantus Aero Striction series

It depends on your budget,
Wolf

[a4eaudio]

If the baffle was narrow enough with a big edge radius I might try the AMT3-4 alone.

Well, I can do an 1" radius so that part is okay.
But if I use 10" woofers I'm close to a 12" baffle and if went down to 8" woofers I'm probably at 10" baffle.

[jhollander]

I'd play around with the blender to see where the baffle messed up the 3-4 reponse. The wider baffle on my Vultus project added a bump and dip where I needed a super tweeter. The narrow baffle on my C-Cake project had a better on baffle 8-12K response. You can do a 4-way with XSim as a back up plan similar to Eric's 442 project.

[donradick]

Wolf , donradick - tagging you both specifically since you are recommending the RT-5002.

While I hoped to stick with a Dayton tweeter, for this application I think I may need to broaden my opportunities.

Veering from the original thread title and based on the comments so far, I think I would consider (a) the Airborne 5002, (b) one of the variants of the Bohlender Graebener Neo3 (PDR or not) or (c) something else if someone said there was a clear 3rd option that I am missing. Its hard to figure out where these AMTs/Ribbons can REALLY crossover from just the specs, but the tweeter would be crossed around 2,300Hz to a Dayton PM180-8.

Also, I just bought a pair of Satori TW29RN-B on eBay just because the price was too good to pass up. I could just use them if that is a clear best answer.

I've used the Neo3 PDR now in 2 builds, and it will do 2.5K 3rd order. I like the sound, but expert measurements show HD a bit higher than I would prefer. I was not pleased with crossing it at 2.1Khz in a LouC design.
OscarJr's measurements show the 5002 with much lower distortion than the 4001. I think he does solid work. Don't know how low either could be crossed, but I'd be considering a waveguide for either at 2.3Khz.
But budget is always a factor.
Thinking about $100 for an AMT makes the $30-40 SB tweeters look very good if you need to crossover lowish.
Hope this helps!

[guitar maestro]

The Hygeia RT-4001 is exceptional, IMO. HD stays well below the fundamental even after it starts to roll off on the low-end.





It's output does start to drop at around 2k. This is the 1.7 sensitivity, so it would be ~3.2 dB higher at 2.83V. Plenty of output to mate up to a 90-92 dB @2.83V-1m midbass/midrange.



If you horn-load it and either use notch filters or DSP EQ, you can easily extend the useable output well below 2k since the HD is very tightly controlled. Obviously these aren't meant to be mated up to very high sensitivity mids/midbasses, but used within the scope of their intended use, the are excellent. But the RT-5002 is an another level, with it's sheer output, and with my diaphragm modification that reduces 3rd order (and thus THD) even further almost into the range of amplifier-like levels.

No throat matching so FR looks rough, but look at the sheer output with ≈1W input. Throat matching works wonders since the horns I tried were meant for 1" C.D.












Yup, big fan of AMT's.

[donradick]

@GuitarMaestro - you are the man! Gotta respect your thoroughness and science.

[scholl]

Wow! the 4001 does look good. Few devices are that good much below 3Khz.

I just got a pair of 18 Sound 6ND430-8s and was also thinking of replacing the SB 29 which has low THD above 3K. I was also considering a WAvecore semi horn tweeter but with the 4001 looks to be useable to 2.5K easy. I like the tweeter to be 2db lower than the mid and the mid 2db lower than the woofer.

How do the other Airbornes look?

Thanks!!

[Wolf]

I love the 5002, that is a marvelously clean unit.

I used the slim RT4101 in the Fenghuang, but it's more of a supertweeter unit at 7.5kHz+. I liked it, and what it added to a 5" full-range. Difficult to mount, quasi-open-back, rear is not flat, and takes tiny screws.

The smaller RT20021 is more limited use as well like the 4101, and does not play low. It's most similar to the Mini-8 from Dayton.

Later,
Wolf

[guitar maestro]

The Hygeia RT-50021 (Hygeia is the oem mfg) is even better than the 4001 in almost all respects. Lower distortion, massive output for it's size, depending on where you measure, it can be regarded as a 97 to 100dB 2.83V@1m sensitive driver. DCR is ruler flat as most other AMT's and planar magnetic spiral ribbons.

Horn loaded with the Dayton H110 horn, it's a beast for it's size, with approximately + 15-17 dB gain from 1k-2k. With my unique diaphragm modification, I can get 3rd order almost non-existent, and THD drops even further as well. With EQ (or notch filters) you can go as low as 1,3kHz albeit with a sharp filter. Graphs in a little bit.




Average THD from 2k-10k: 0.2% with roughly 10dB gain from it's reference 1W sensitivity.










Before-and-after horn loading with the H110 horn, with fiberglassed throat, near perfect throat-match, but still off a few mm (I need to make iteration #2 to really squeeze out more dB!)








relative gain, horn-loaded vs stock:







stock vs modified diaphragm THD:








Quantitative Data for stock vs modified diaphragm (from a different trial run altogether), but back-to-back, same diaphragm reinstalled in the housing:







and finally, bone-stock with no EQ vs horn loaded with modified diaphragm with EQ to flatten out the response:










Distortion plot for the scenario above. Above 2.2kHz, the seemingly lower THD is because the output itself is notched down, so there is no real reduction other than what I posted in the other plot. But below2.2k the reduction is very much real as I obviously did not notch/EQ anything down in that region since that is the region that I wanted to be louder.

[a4eaudio]

Thanks all for the input. Knowing that jhollander, PWR RYD and Wolf have all used the RT1.3WE and been very pleased with the sound I think I will start there. It would definitely be satisfying to build something that sounds good with a $36 tweeter vs a $150 tweeter. Considering the price of the RT-4001 I may buy a pair and experiment between the two.

guitar maestro - do you have any threads on your experiments on horn loading or other's threads you recommend? I see your term "throat matching" and know what you mean but don't know where to look to understand better. I know there are some threads on DIY Waveguides that I've never read, so maybe its time to do some learning.