Any interest in an ASR community speaker project?

[617]

Looking to see were this project goes and maybe one day make the speakers myself.

About the midranger/full ranger (even woofers), may I suggest Faital/Faital Pro products?

That's a good reminder. The 4FE models have beautiful FR charts and are priced well. They have very low xmax, but if a reasonably high crossover is used they would be a good option. I suspect something like this would work better than a fullrange which is trying to hit 100hz.

 

[zermak]

I was looking for them while figuring out which fullranger get for my desktop speakers but I ended up with a MarkAudio pair (mostly the look won over them).

I didn't read all the discussion yet but I think the 4 in from Faital can do well from 200Hz up to whatever the tweeter needs. I can't find and never found any distortion test tho so it's unknown territory.

 

[HooStat]

I really, really liked the idea of a sealed box, but going 8" vented looks sensible.

If that is what is desired, then let's focus on how to make that work. I say this selfishly because I want a sealed speaker -- I certainly defer to the group. But what if the budget adjusts to accommodate drivers that will make it work?

 

[617]

If that is what is desired, then let's focus on how to make that work. I say this selfishly because I want a sealed speaker -- I certainly defer to the group. But what if the budget adjusts to accommodate drivers that will make it work?

We have a ways to go before any kind of clear direction is reached.

The two options regarding woofer size:
1. 10", sealed, requiring a 4-5"+ mid and a bigger waveguide and tweeter
2. 8" vented (or PR, builder's discretion), requiring a 3-4" midrange and requiring either a small waveguide or robust tweeter.

#2 has the same output and a more slender cabinet than #1 at much lower cost. Hard to believe, but I've been running the numbers. There's a reason why every damn speaker on the market is vented! #1 actually has a smaller cabinet - it would end up being wide but not very deep.

The 10" starts to make sense for a 'big' stand mount speaker, with a big 5.5" midrange, 1' wide cabinet, and a sizeable waveguide on a robust tweeter. I wouldn't count that out, but when you go with a sealed 10" you're paying for more woofer for the same performance as the 8".

The sealed design has a certain appeal; it's easy to make, sub integration is easier in theory.

The third option is a legitimately big speaker with a 10" in a big vented cabinet, 6" mid and 6" waveguide. This becomes a big floorstander and at that point the mid-treble directivity is very similar to any number of 6" WG speakers out there. At this point you would be best off making a 6+1 speaker with a waveguide and plopping it on top of a bass module or just using subwoofers.

Whatever direction this project goes to, the whole process will continue to be publicly documented, and all the files in my dropbox, so a DIYer with some gumption could relatively easily make a speaker of their preferred size. The DSP makes the DIY a bit less intimidating.

Also; wild card. Stand mount dipole with monopole bass. I know I'm not the only one interested.

 

[jhaider]

As far as which drivers here look best to me, it's hard to say. The ubiquitous RS225 is a solid choice, as is the RS225P. The Peerless Nomex is quite attractive, but has a an odd baffle shape which is a little tricky to recess using DIY tools.

Is surface mounting the woofer (not midrange or tweeter) the worst thing in the world? My hesitation with Dayton drivers is global availability. The same applies to Denovo Anarchy, a really high performance and high value 7" woofer for a small 3-way that many people will never be able to source. Tymphany/ScanSpeak/Seas/B&C are distributed in most of the world.

(Speaking of B&C, did you look at the 8BG51? It may be over the intended budget, but it ticks a lot of boxes: big voice coil for higher power handling, solid xmax, typical excellent B&C motor design, a half roll surround for more "hifi" Fs. Downside is the octagon frame.)

The ScanSpeak really wants a big box, but has high efficiency - it would be a great choice in a passive design.

One nice benefit of active is that T/S parameters lose relevance almost entirely. Available power, power handling, and volume displacement determine bass cutoff. You take the box you have, model the driver in the box and tune the box to where you want the cutoff to be if it's vented, EQ to fit your target response.

Erin measured the ScanSpeak 22W-8534 on his old Klippel. While I can't find the data, the drivers he measured are in my basement right now. Alas, the intended project (compact closed 3-way for use in a bass managed system) never happened because the guy I was planning to build the cabinets for me (Del Won) moved from NoVA to Hawaii. I'm not saying it's the best choice for your application, but I don't understand the reasoning above.

 

[HooStat]

The two options regarding woofer size:
1. 10", sealed, requiring a 4-5"+ mid and a bigger waveguide and tweeter
2. 8" vented (or PR, builder's discretion), requiring a 3-4" midrange and requiring either a small waveguide or robust tweeter.

8" sealed and 4" mid would just sacrifice bass extension in a sealed box? (And what is "PR" in option 2?)

 

[617]

Is surface mounting the woofer (not midrange or tweeter) the worst thing in the world? My hesitation with Dayton drivers is global availability. The same applies to Denovo Anarchy, a really high performance and high value 7" woofer for a small 3-way that many people will never be able to source. Tymphany/ScanSpeak/Seas/B&C are distributed in most of the world.

(Speaking of B&C, did you look at the 8BG51? It may be over the intended budget, but it ticks a lot of boxes: big voice coil for higher power handling, solid xmax, typical excellent B&C motor design, a half roll surround for more "hifi" Fs. Downside is the octagon frame.)



One nice benefit of active is that T/S parameters lose relevance almost entirely. Available power, power handling, and volume displacement determine bass cutoff. You take the box you have, model the driver in the box and tune the box to where you want the cutoff to be if it's vented, EQ to fit your target response.

Erin measured the ScanSpeak 22W-8534 on his old Klippel. While I can't find the data, the drivers he measured are in my basement right now. Alas, the intended project (compact closed 3-way for use in a bass managed system) never happened because the guy I was planning to build the cabinets for me (Del Won) moved from NoVA to Hawaii. I'm not saying it's the best choice for your application, but I don't understand the reasoning above.

- Your point about availability is well taken. Dayton offers really good value for people in North America, and the amps we're looking at are Dayton products, but I have also noticed tymphany/Scan/SB are more available worldwide. If there is significant international interest, it would not be hard to suggest a driver set which is more available overseas. Part of the reason I'm doing this design in a very public and collaborative way is so that people who inevitably want to use something different can take from this process a lot of information on how to design this speaker.

- I will look at the 8B - I didn't look at B&C drivers initially but I know they make some killer stuff. The driver in question looks like a beast with ample headroom. $120 is not crazy for a driver with this kind of spec.

- I'm still stuck in passive land when it comes to T/S. I did however shoehorn each 8" driver in the same cabinet and tuned it for maximum SPL at 30hz - see that post. The drivers were very close in performance. I can add the Scan Disco to that list.

This is the Max SPL graph for all the variants of the 8" woofers. As you can see, they vary quite a bit in how much of a dip they incur around the tuning frequency. Does this really matter? I guess not, but it does limit headroom in the 40-60hz region.

Thanks for your input on the bass issues, it's weird adjusting to the freedoms offered by DSP.

 

[617]

8" sealed and 4" mid would just sacrifice bass extension in a sealed box? (And what is "PR" in option 2?)

8" sealed - quietest
8" vented or 10" sealed - same output
10" vented - loudest

PR stands for 'Passive Radiator' which is for all intents and purposes the same thing as a vent.

 

[KSTR]

IME a vented design can only be perfect with pretty large volumes, much larger than typically seen. With "perfect" I mean really zero port noise even at maximum level sine wave exitation at the Helmholtz resonance. This requires low air-flow velocity --> wide port with perfect roundovers on both ends (and even that is not going to be perfectly symmetric for air intake vs outtake). Wide means short as well and that means a large volume for the given resonance, compared to a longer, narrower port in a smaller cab for the same resonance.

Ported designs also also more prone to nasty "jump resonance" (a semi-chaotic phenomenon), the mentioned asymmetry being one reason and the second one being woofers with too soft suspensions (low restoring force for the tendency of the VC to go dynamically off-center at certain frequencies). For a low resonance freq of the driver a hard suspension requires a large moving mass. That's the design rationale behind all of the better pro-sound woofers, B&C notably. Bottom line: Typical HiFi-woofers don't really work in ported designs if we aim for excellent behavior. PR has no port noise and lower midrange leakage but has its own set of problems (the instability can be worse with them sometimes, as can distortion).

 

[Biblob]

I think the SB10 is going to be too small. Revel is using a 4" midrange and I think something like the RS125p, Vifa NE123 or something is going to end up working better. Let's have a look for bargain 4" fullranges, I'm sure there are tons I'm missing.

So maybe one 'high end' option is ($234)
SB23 - $110
NE123 - $63
SB26STAC - $41 (I think the soft dome performs better in the WG, we can discuss this)
waveguide - $20

But a better value would be ($139):
RS225/p/4/8 - $60
RS125- $34
SB21RDC -$25
Waveguide - $20

I honestly don't think the more expensive option would be any better here.

The midrange is the biggest unknown. There are a very limited number of tested waveguide designs, for under $50 we have the RST28 (WG too big) and the sb26/sb21. The CSS LD22 is a great unit but overpriced at $75. 8" woofers we've narrowed down pretty well - and the old medley's musing's page ranked the sb23 and rs225 as being very close to each other in distortion, so their performance differences have more to do with bandwidth at both ends. I strongly suspect the 3.5-4.5" class of midranges is going to match best with this waveguide, and so called 'fullrange' drivers are very plentiful these days, so this would be the best place for more research.

For a 4 inch midrange, the SB12MNRX2-25, look to me like a great compromise. It can also live up to relatively high output of around 104dB above 400hz.

 

[Peas]

I love the idea of the 8" + 4" + 1" combination as it can be a powerful yet compact design. I had this myself, it was my first own design with a 8" hexacone woofer, W4-655 and an AMT coming in at 3.3 kHz.

It can also be done in a monitor style such as the Neumann KH 310:

http://forum.visaton.de/showthread.php?t=28907

http://winboxsimu.de/Boxen24.html

A sealed design may be suitable for typical close-to-a-wall positions. It may also be assisted by a serial capacitor.

The afore-mentioned W4s such as the W4-1320 are good midranges when combined with a tweeter. I recently built something tiny with the BB4 black, which is the 4-Ohm version of the 1320:



It also makes some serious bass. But highpassing it at 300 Hz or so would be perfect.

But I am not sure if I can help as I am located in Germany.

 

[jae]

For the "guts", a raspberry pi + mini dsp OEM + purifi/hypex modules and psu would be a good base for a DIY active speaker design and would neatly cover streaming, dac, amplification and power with readily available parts that measure well. Not "cheap" though

 

[TimW]

What about:

RS225P-4 ($63)
RS100P-4 ($34)
BC25TG15-04 ($15)
Total: $112

?

 

[Mashcky]

I’m biased in favor of a sealed speaker in 8-4-1 configuration due to smaller size and ease of construction. Cost is an added bonus as well by saving on the port, additional 10” driver cost, and cabinet materials.

Does the decrease in efficiency justify the additional cost of a 10” or ported design? On the flip side of those cost saving is a need for more watts...

Another thought that crosses my mind is that ASR is heavily of not only into waveguides but bass management. Should an ASR design be sealed to optimize for sub integration and therefore bass management?

 

[dwkdnvr]

Taking a step back, I think we have to be careful not to get too deep into 'bench racing', although we do need to keep a system philosophy in mind. There are designs out there like the DXT-Mon and the ER18-DXT that achieve very good overall directivity behavior despite the individual drivers not being perfectly matched at the xover point. Taking a look at what Mark K did with the ER18-DXT in particular might be worthwhile - it's actually been quite a while since i looked at that design. (maybe it's no co-incidence that both use the DXT. the only off-axis I've seen for it is here http://zaphaudio.com/offaxis-27TBCDGB-DXT.gif although Mark K probably has measurements available through the archive. ) I did actually buy the plans for the DXt-Mon, but have never simulated it to see how it achieves what it does.

Also, even highly regarded designs like the F208 and F35 have dips in the DI curve above xover. Given that for the F208 in particular the resulting 'in room' PIR looks very smooth, it's not impossible that this is deliberate to compensate for vertical off-axis behavior, although it's also possible that this is just a marketing compromise - raising the xover to protect the tweeter to reduce support costs even if it slightly degrades performance.

It might be necessary to get to the point of throwing up a measurement rig and quantifying some of the behavior we're concerned about, although we would obviously need to winnow down the list of ideas dramatically in order to make it manageable. We also won't ever be able to reproduce the full picture provided by the Klippel NFS rig, which will make PIR tough to evaluate, unfortunately.

So, I think ultimately the first question(s) we need to ask/establish:
- waveguide for the tweeter, or not?

For some contrast, after going through many of these same thought processes, for my main/living-room project I'm tentatively going with 'no waveguide', using the DA25Tx and SB15NBAC, and aiming for a very low xover - 1.6kHz - hoping that on a wide-ish baffle this will be 'good enough'. I have put together a preliminary waveguide using ATH4 just to try cutting it on my CNC, but I haven't measured it yet. I may have to re-tool this approach once I get to measurements.

 

[dwkdnvr]

For the "guts", a raspberry pi + mini dsp OEM + purifi/hypex modules and psu would be a good base for a DIY active speaker design and would neatly cover streaming, dac, amplification and power with readily available parts that measure well. Not "cheap" though

IMHO this is a perfect example of why I made the point earlier about decoupling the design of the speaker from the DSP implementation. What you outline is a perfectly viable way to attack the problem. But, at $2k+ to implement, I have no interest in it since I already have my 'expensive' DSP setup in place - if this was part of the 'project direction' I'd just move on to something else.
Fortunately, it's not difficult to keep the concepts separate as long as people come in with the right perspective.

 

[dwkdnvr]

Another thought that crosses my mind is that ASR is heavily of not only into waveguides but bass management. Should an ASR design be sealed to optimize for sub integration and therefore bass management?

Well, this is to a degree the elephant in the room (or at least one of them). Are we aiming for a design that is a complete standalone system intended to be used without subs, or is it a design where we intend to enable integration with a multi-sub setup? IMHO advocating a DSP speaker design intended to be used with subs but not actually having anything in place to implement the integration is a bit of a problem. Enabling multi-sub integration isn't too hard if you use a DSP setup with enough channels (e.g. MiniDSP 4x10 or Nano-Digi), but is tougher to wrap your head around in the case of something like the Dayton DSP amps - how do you handle things like global delay alignment when you have N independent/unconnected DSP configurations? You can probably do it, but it's not going to be fun.

I think @617 was really hoping to have a design that was intended to stand alone, which is why he was going for a 10" driver. I have used the Dayton RSS210HF as the bass driver in a sealed system, and it actually did really well until I put it into our 10000+ cubic foot open space at which point it struggled. If we're targeting smaller spaces though, a sealed 8 with enough output can IMHO be a completely standalone system for music. If we're aiming for something that would handle a really big room though, IMHO we need more headroom.

And, going back to @Thomas savage original post, he had 'room correction' as part of the list of requirements. If we want to include at least of guidelines as to how to implement/integrate this design into a room correction system, we need to define what the expectations are. Certainly we aren't going to implement an actual automated RC system as a part of this, so it's a question of approach. IMHO this boils down to eiither
a) show how REW can be used to create correction filters that can be imported into this system
b) selection of a DSP platform that has Dirac or something equivalent already integrated.
c) (maybe) FIR filter integration so that DRC-FIR or Acourate filters can be used

Only a) really preserves the "DSP implementation independent" idea that I've been advocating, so that is my working assumption at this point. Since this is an open discussion about community direction though, alternative ideas/proposals are definitely welcome.

 

[somebodyelse]

Well, this is to a degree the elephant in the room (or at least one of them). Are we aiming for a design that is a complete standalone system intended to be used without subs, or is it a design where we intend to enable integration with a multi-sub setup? IMHO advocating a DSP speaker design intended to be used with subs but not actually having anything in place to implement the integration is a bit of a problem. Enabling multi-sub integration isn't too hard if you use a DSP setup with enough channels (e.g. MiniDSP 4x10 or Nano-Digi), but is tougher to wrap your head around in the case of something like the Dayton DSP amps - how do you handle things like global delay alignment when you have N independent/unconnected DSP configurations? You can probably do it, but it's not going to be fun.

I think those Dayton/Sure/Wondom amps expose enough of the DSP's I/O that we should be able to keep things in sync with a sub. Exactly how will depend on the source and the sub.

 

[617]

If the core motivation is to 'involve the ASR community' and 'have fun', the design goals will naturally be vague, and consensus will be hard to come by. I've struggled a bit regarding consensus as a driving force in this project, since a lot of interests need to be weighed, and so far I'm the only person stupid enough to take ownership and put money on the line. In general I intend to build something I like. At the same time, my judgement is heavily influenced by the community since, for one thing, they know more than me, and for another, I would like to build something that others want to build. If and when the project converges on a natural consensus (for example, we find a good 8" driver which does well in a sealed cabinet, and the amp tests come back positive) I expect the project will become more collaborative.

To offer a more specific design brief:
1. Unintimidating size - ideally something affordable to ship, but certainly something you can pick up without a hernia.
2. Good value - this is not a 'giant killer' or 'SOTA' speaker, but one which uses high value parts and achieves high performance
3. High performance

a. First priority is smooth FR and DI from the midrange on up. ASR is really the only place where you can get useful data about speaker dispersion​

b. Second priority is headroom/dynamic capability and bass extension​

4. Somewhat novel design - in other words, not duplicating the efforts of 1000 diyers.
5. Unintimidating to new DIYers

Some notes on these design priorities:
2. When you analyze parts cost, certain price thresholds start to emerge, and you start to see that there is a whole class of drivers which, although not cheap, give you 80% or more of SOTA performance for very little money. The biggest bargains tend to be in midrange drivers and tweeters, where the actual material costs of the product are comparably low (with woofers, to a greater extent, you get what you pay for.) Modern 60 dollar tweeters really are competitive, with some restrictions, with 200 dollar tweeters.

5. The desire for the design to be unintimidating to new DIYers is a somewhat unique priority. Most ambitious diy speaker designs assume a high level of knowledge of speaker building and testing. Using a DSP amp, which you can program on your computer, not only offers better performance, it allows people who don't know how to solder the ability to make a really great speaker. Going sealed, similarly, simplifies construction as port tuning is eliminated and cabinet wall lining isn't as important. I am also trying to avoid the need for waveguide fabrication, but given the proliferation of online 3d printing services, I feel this isn't as much of a barrier as it once was.

 

[617]

Now, regarding woofers. I still would prefer a sealed alignment for the simplistic reasons I can articulate, and the more sophisticated reasons others have articulated. Whether or not this makes sense remains to be seen.

An 8" woofer offers better directivity matching to a midrange which is in turn small enough to match well to a direct radiating tweeter, or tweeter in a small waveguide. Basically, when you go to a 10", the size of the mid goes up, which makes life a lot harder for the tweeter. So, an 8 is preferable.

The question is - what do we give up by going to an 8" sealed driver?
Here's some data:

This is a list of the simulated 8" woofers sorted by their output at 40hz (not 30hz.) The best woofer is the SB23 MFCL, which is a poly sub from SB acoustics. This would be a great option, but I believe for this 100db output it would require something close to its rated power, which is in excess of what the amps we are looking at can provide. I will do some simulations to see if the driver is xmax or power limited, but I assume it is the former.

The next driver down is a surprising one, the Tang Band w8 2096B. In the case of this driver, a picture is needed:

This fat little beast has an RMS rating of 80W, and will offer 98db at 40hz and 107db at 100-200hz. Price is $122.

The next option is the unavoidable, ubiquitous RS225-8. I once did calculations of EBP for a whole database of woofers and this guy was close to the top - it is really well suited to sealed enclosures. Of course that's passive thinking - what can it do in a sealed, DSP filtered alignment? Well max SPL at 40hz is 96db and at 200hz, 105db. The paper variant does the same in the bass but goes a bit louder on top, 108db. Price is $59 for the aluminum and $63 for the paper. The paper has a very extended response and has been used in a few 2 way designs.

A quick word on these dB simulations. These are at 1M, half space. At the bass frequencies, below baffle step, you would expect to see 6db loss due to the transition to fill space. Also, if you go to 2M, you subtract another 6db. However, you're going to be running these as a stereo pair, and since bass is mostly mono, you can expect 6db gain. So, and someone please correct my math here, as a rule of thumb, expect 6db less output at 2M in room. Baffle step is going to be in the region of 350hz for this kind of speaker.