Some Interesting Drivers, a New 3-way Project

[b_force]

SB15NBAC30

Best is class especially price/performance ratio.
Especially as just a mid (the low-end isn't so super great)

You can go for the NRX, tiny bit cheaper performance almost the same.

I really doubt the MCA15RCYwill be better, maybe we can find some measurements.

 

[Tenson]

I've only skimmed this thread so apologies if I missed a key point. I'd add that leakage of cabinet modes is not insignificant when considering port placement (not so much profile). In larger cabinets the modes will be lower in freq. and I don't believe they are inaudible simply because they are below 400Hz. Personally I find decay issues very frustrating in the lower vocal range.

A BEM simulation of the internal cabinet modes might* provide some ingiht on more optimal port placment. Woofer placement is also critical, but probably not much room for play there I assume.

*I had issues using BEM for my small speaker example, but with a larger enclosure and where the port represents a far smaller percentage of the cabinet volume, it could be far more informative (since moving the port also changes the internal geometry).

 

[b_force]

In larger cabinets the modes will be lower in freq. and I don't believe they are inaudible simply because they are below 400Hz. Personally I find decay issues very frustrating in the lower vocal range.

Well, without fancy BEM tools, we can already get an estimate.

Let's assume that the internal dimension is roughly 80cm high.
so; f = 344/(2*L) = 344 / (2*0.8) = 215Hz

Worst of all, most damping materials don't work great at these lower frequencies, so you'll need A LOT of it.
Or come up with other solutions (as mentioned above).
yes, I agree that it can sound awful.

For the sides and depth this is gonna be roughly around 400-600Hz.

 

[hifijim]

@b_force, I agree the SB15NBAC is an excellent driver. But I have used it and its sister (SB15CAC) in two recent projects, and I want this project to be "completely different"... All new drivers, passive crossover, bass reflex design... for me, these are "completely different". So I won't be using either the SB15NBAC or SB15CAC.

https://www.diyaudio.com/community/threads/new-project-tower-3-way-with-twin-8s.378223/post-7142703
https://www.diyaudio.com/community/threads/compact-low-cost-active-3-way-speaker.402812/post-7558072

 

[b_force]

@hifijim That is totally fair enough! 🙂

Since you're in the US, the Dayton RS150 ain't bad either.
Better midrange compared to the SIG 5 inch.

Or otherwise some Wavecor maybe.

 

[hifijim]

With a 5 inch mid-woofer, you need at least a 5 inch waveguide.
Otherwise you will never get the directivity right.
3-3,5kHz is to high to be able to combine this well with a 5 inch woofer.
You will always see a discrepancy in the directivity curve.

Thanks for your insight.

I have run some sims which seem to show that I can use 5" mid. The following VituixCad sims use the measured polar response of the SB26STWGC tweeter in the XPS foam prototype, combined with the measured polar response of the SB15NBAC30-4 driver in a cabinet of very similar width. This is a feasability study, not the planned implementation. All I am looking for at this point is a demonstration that I can manage the DI throught the crossover region, from approximately 1k to 6k

First, I implemented a filter using active components. The variation in DI from 1k to 6k is 1.5 dB

Next I implemented a filter using LCR components. I did not spend much time optimizing it, and I got a variation in DI of 2 dB.

So from a feasibility standpoint, I feel comfortable considering both 4" and 5" drivers.

 

[b_force]

You do notice the discrepancy around 3500Hz 😉

But yes, all depends on definition and how strict and accurate you want to have things. 🙂
If you can live with that, great and you've reached your goal! 😀

 

[mordikai]

other good cheapish mids: the nbac may be better than all of these.

Zaph ZA14

SB12MNRX2-25-04​

Scanspeak 15M/4624G Discovery​

Aurum Cantus AC-130F1 5-1/4​

 

[Juhazi]

Second vote for ZA14. It's 8R
https://www.madisoundspeakerstore.c...aph-audio-za14w08-5-aluminum-cone-mid/woofer/
https://hificompass.com/en/speakers/measurements/zaph-audio/zaph-audio-za14w08
http://www.zaphaudio.com/ http://www.zaphaudio.com/ZA14W08/design.html

Problem when searching for mids is that "nominal diameter" is sometimes with the frame, sometimes radiating area diameter, or something between them. above 3kHz differences in response and directivity are huge! Surround shape, cone profile, dustcap/phase plug profile are very important. Specific mids tend to be smoother.

ZA14

Audax HM130 https://www.madisoundspeakerstore.com/approx-5-woofers/audax-hm130z10-aerogel-5.25-mid/bass/

 

[b_force]

Phase plug is always extra points.

They just look cool 😎

 

[mtidge]

I tried using a aerogel Audax HM130-Z0 mid when I started designing a 3 way stand mount because I already had a pair. I finally gave up on it and used the SB Acoustics SB12MNRX2-25-04 instead combined with an 8 inch SB23CACS45-4. The main problem I had with the SB12MNRX2-25-04 was the 5 db wiggle at about 1.5Khz. I thought it was diffraction from my baffle, but in the end it seemed to be caused by the surround. The rough response of the HM130-Z0 was the reason I gave up on it, not to mention the difficulty I would have trying to flush mount it. Maybe the HM130-Z10 doesn't have the rough response I had with the HM130-Z0. Lastly, for Jim, the SB23CACS45-4 is a 4 ohm which he said he doesn't want. Here is the frequency response of the 3 way showing that I could not get rid of the 5db wiggle.

 

[hifijim]

The Sig225-4 is out of stock, so I have to wait a while.

Two midrange drivers which are at the top of my list are the Scan-Speak 10F/8424G and the SB15CRC30-8.

 

[b_force]

Scan-Speak 10F/8424G

These a very SPL limited.

With a 4 inch you want at least 40W or more and a proper sensitivity.

If I remember well, the CRC has an issue in the distortion from some kind of resonance. I have to look up the measurements again.

 

[hifijim]

With a bit more tweaking, I can get the DI curve to be essentially flat from 1k to 6k. Once again, this is just to see what is possible.

 

[hifijim]

These a very SPL limited.

Really ! that is interesting, and I had not heard that before. I thought they were fairly highly regarded. The response curve looks very easy to deal with, flat to above 8k...

Any additional objective or subjective comment on these would be appreciated.

 

[Juhazi]

I have a pair of Audax HM100Z0 (NLA), Aerogel, which is close to 130Z0. No such wiggles, which are very bad with Vifa NE series

I tested them as narrow baffle dipole and finally used with a sealed box 3-way with LR2 acoustic (dsp)





Vifa https://loudspeakerdatabase.com/Peerless/NE149W-04

 

[b_force]

Really ! that is interesting, and I had not heard that before

Just look at the data 😉

I have used them before.
Very great and easy little drivers, like you said
These days I find them overpriced.
They used to be around 70 bucks, which is more fair.

For that money I would just go for a B&C 4 inch mid or so.

But what is your budget at this point?
Because I have seen all kinds of things passing by now?

 

[b_force]

I have a pair of Audax HM100Z0

Do you have some distortion measurements as well?

 

[tktran303]

I see the angle that @b_force is coming in regards to the 10F 8424G. With a sensitivity of about 86.5dB and power handling of some 30W, and cone diameter of about 2 3/4" and 2.5mm x-max, it won't be able to play very loud (or very low)

But a single vented Sig225-4 is limited to about 96-98 dB@1m after baffle diffraction losses anyhow. So it might need to play so loud.

Anyhow back to the 10F, I'm not sure why Scan-Speak suggests a lower limit of 150Hz. @HiFiCompass clearly shows that it's ideal operating range is above 500Hz

 

[Juhazi]

Do you have some distortion measurements as well?

Some, but with quite low level. I bought them ten years ago and tested as dipole - abandoned. Then protoed as sealed in 2018 and finalized the modified Avalanches in 2021.