Quality 2-way standmount: reasonable low frequency extension?

[jimmyjazz]

I am curious to hear anyone's thoughts on what a practical -3 dB frequency (on axis) might be for "good" standmount 2-way monitors. Any commercial examples would be great, but certainly not necessary.

Assume boxes in the ~ 50 L range, and also assume that loudness is not a big concern.

Is it possible to get down to the 30 Hz range?

 

[kec]

Not exactly stand mount, but it's < 50 liters and reaches the 30's. Dayton RS225-8 aluminum cone cast basket. Currently, I have the BIG Heil on top of the cabinet.

 

[jimmyjazz]

Very cool! What is the crossover frequency?

 

[kec]

800 Hz using miniDSP

 

[ILikeFoodz]

Check out some of the SBAcoustics woofers (sb15 or sb17 series) and pair with a tweeter that can cross fairly low. Just know that achieving the goals you've laid out will require some compromises.

I recently built a pair with SB15NAC30-8 and SB26STAC-C000-4 in a volume somewhere near 1 cu.ft. (can't remember exact volume). Sounds excellent, reaches the upper 30s. The major compromises are that the woofer will bottom out at low frequencies above about 96 dB and the harmonic distortion becomes quite significant in the bass frequencies for such a small woofer.

Using the SB17NBAC35-4 or -8 would result in a slightly different set of compromises that probably would turn out nice as well (higher order crossover, somewhat bigger box, but better and lower bass).

 

[Lojzek]

I find Peerless 8" PPB and nomex cone also, a favorite woofer capable of decent midrange performance, once it's crossed over to a waveguide tweeter.

 

[dtaylo3]

You should be able to have an 11 to 16 liter box that goes down into the 40s and a SB Acoustics ported aluminum, poly, paper or ceramic 5.5 or 6 inch driver. Lots of kits out there. Look at Meniscus Audio kits in the USA. Also look here:
www.audioexcite.com

 

[jimmyjazz]

Good stuff, thanks. I'll play around with it.

If we take dome tweeters out of the equation, what's a reasonable crossover frequency for ribbons, planars, etc.? It looks like some planars on Parts Express have claimed low frequency extension down to 150 Hz. Are they anywhere usable down there? Some ribbons are also spec'd below 1 kHz. What's a realistic estimate for how low a real-world crossover might get?

 

[5th element]

Actually the 8 ohm 6" Satori driver from SB Acoustics will play down low in 30l ported cabinet. That'd be one deep stand mount speaker though!

 

[Ugg10]

@wolf_teeth on here produced the Attitude speakers that may suit the bill. They are 3 way stand mounts but run a Dayton rss210hf-4 as a bass driver, 2" dome mid and a ribbon tweeter. The RSS210hf-4 works well in a 1cuft ported cabinet (28.3l) and according to the designer it will run fairly high without problems to cross over to the 2" dome (guess at around 750hz-1khz). Image of it here at bottom of 1st post -

Wolfy's armada.... -

Techtalk Speaker Building, Audio, Video Discussion Forum

Putting the RSS210hf-4 data into the MH-audio ported cabinet calculator for a 28.3l volume fb gives an F3 of 27hz with a port of 5cm diam and 23cm long.


Swap the unavailable Usher 2" dome for a Morel MDM55 and you could have a very nice speaker, and if you don't like the ribbon tweeter use an SB26ADC for that top end sparkle.

 

[Roby60]

For quality commercial examples, i'm in love with Klinger Favre D series.

 

[jimmyjazz]

Putting the RSS210hf-4 data into the MH-audio ported cabinet calculator for a 28.3l volume fb gives an F3 of 27hz with a port of 5cm diam and 23cm long.

Thanks so much. That's an impressive driver. I have a lot to learn -- what is it that makes it so capable in a relatively small enclosure? I have many of Richard Small's papers and understand the basic tradeoff between f3, Vb, and efficiency, and I've even done some work going beyond that to try to assess specific driver T/S parameters to predict what might work well in a small enclosure, but clearly I'm not hitting on all cylinders, because I overlooked that driver.

 

[Ugg10]

It’s basically a subwoofer with larger excursion but will reach around 1khz before you get break up rather than the usual 250-300hz but therefore needs the mid driver (also look at the Sb23mfcl) whereas a more traditional woofer of similar size will only reach down to the high 30’s but will reach up to 2khz plus and so integrate directly with a tweeter like the sc29rdc.

 

[jimmyjazz]

Yes, that alludes to one of my earlier questions -- if we can find a "tweeter" that reaches down into the hundreds of Hz with any reasonable performance, wouldn't this allow a 2-way with a simple crossover that's lower than the general problem areas?

 

[Ugg10]

You could look at some of the smaller markaudio alpair or tang band full rangers, there are a number of 3-4” drivers that could do that. Whilst not conventional an 8” subwoofer plus a 3” full range crossed over at 3-500hz may just work.

Examples.

Markaudio | KJF Audio

https://www.parts-express.com/pedocs/specs/264-861-tang-band-w2-748sg-specifications-47064.pdf

https://www.parts-express.com/pedocs/specs/264-844-tang-band-w3-1364sa-specifications-45311.pdf

 

[jimmyjazz]

Cool, thanks. Are there practical concerns for pushing planars (ribbons, AMT, etc.) down to the bottom end of their "spec" range?

 

[chris661]

Distortion. Ribbons don't like to run low. Quite often the "ribbon sparkle" is increased 3rd and 5th harmonics in the mid-kHz range.

There are some shootouts on Zaph Audio, which is another great resource.

Chris

 

[jimmyjazz]

Great, thanks. I'm learning a ton.

 

[LineSource]

The 8" aluminum cone SB23NACS45-4 crossed LR4/LR4 at 1kHz to the Wavecor TW030WA11 (4-ohm) simulates well. What size-shape front baffle are you considering?

Build a 1"+5"+8" design.

A cabinet with 50l volume is large enough for a 3-way design using an 8" woofer. Troels Gravensan built several "Classic 3-way" designs with 37-44l cabinets.

Smallest Troels cabs made from 19 mm MDF and are 300 x 550 x 320 mm (W x H x D) producing a volume of approx. 37 litres. The mid cab and the vent will reduce the volume by some 2 litres.

 

[wolf_teeth]

Since I was referenced here...

I measured the T/S of the RSS210HF-4, and the 1ft^3 box, and I mean 28.3 ltrs. With a 2.5" Dia x 10.5" long port, and using 1.5# of stuffing to reduce the low end ripple will yield an Fb/3/10 of 30/26/19Hz.

I had a xover about 850, and the 210HF will do this okay. The real issue is system sensitivity. If you are doing this passively with full BSC comp, you'll be limited to about 81.5dB sensitivity after BSC is compensated. Since I use Crown amps, I have plenty of power on hand. The trade-off to get lower bass in smaller volume is just that- sensitivity loss. Hoffman wasn't wrong.

It's a shame the Ushers are gone, as that midrange is wonderful. The MDM55 or EM1308 would be good drivers to try, and I have a feeling the RS52FN (textile) might also work okay. The issue is the xover point here. The above 3 usually do not end up being able to xover below 900Hz without complaining. (I'm basing my thought on the FN due to others' experience with the AN.) I really feel if the xover was any higher that the woofer stretching to reach the mid would be more noticeable. 800Hz would likely be better, but 850Hz is where they landed and I don't notice this artifact. The HiVi domes can play this low, but the impedance due to the network utilized won't allow it. The Visaton domes have been less than stellar in terms of actual driver measurements. Oh, and I really dislike the RS52AN.

This is why there has not been a revamp on the Attitudes' design. There is no mid-dome currently to suit the needs of the project with the criteria I require.
- 850Hz xover
- 8 ohm nominal impedance
- proper flange size
- low HD
- no ferrofluid
- 2" textile dome

This project is still my reference in a lot of ways. Nothing has surpassed them completely, but I have come close.

Thanks for the mention,
Wolf