Directiva r2 project: market requirements gathering

[TimVG]

r1 is (almost) done. While it could use a bass module to get louder too, the plan for r2 was to use less expensive woofers...

Or did I miss something earlier in the thread?

I may have misunderstood. I assumed you meant by this that R2 would simply be R1 be put on top of an additional bass module. Sorry if I'm confusing you.

I believe if a slim floorstander with pattern control down to ~500Hz (or less) is what you're after, a speaker in the style of the Amphion xenon could be what you're after. It has cardioid behaviour (passive) and an extra large woofer to support the low-end.

I'll see what you guys decide on and if I can be of help with prototyping or preliminary measuring.

 

[Rick Sykora]

Revel f208 clone, let's do it.

While we are spit-balling, not against the idea of an active/hybrid version of something like the Revel F208.

It could fit the extensibility goal by splitting the woofers into a bass module. No shame in doing something evolutionary...

Btw, Amir is too busy too support as much Klippel time as he did for r1, so this might factor into possible constraints on r2.

 

[617]

While we are spit-balling, not against the idea of an active/hybrid version of something like the Revel F208.

It could fit the extensibility goal by splitting the woofers into a bass module. No shame in doing something evolutionary...

Btw, Amir is too busy too support as much Klippel time as he did for r1, so this might factor into possible constraints on r2.

It's not an uninteresting task. It's as much speaker as most people would ever want, it can be done economically, the response can be perfected with DSP, the bass level can be customized to taste, and nailing the directivity is a challenge as well.

 

[TimW]

Am leaning towards slimmer bass module that is tall enough to be a stand for various types of monitor. I also liked the goal to get better directivity below 1 kHz.

I like this idea, are you thinking of something like the Genelec W371A in regards to directivity control?

 

[Rick Sykora]

I like this idea, are you thinking of something like the Genelec W371A in regards to directivity control?

Frankly am struggling a bit with walking before we run...

Comparisons aside, am not very comfortable with taking aim at KEF, Kii, Genelec, etc., until we can demonstrate something simpler. If we can establish an extensible design with improved directivity over r1, then maybe we can aim higher. We may have some very smart people, but we are not full time and/or otherwise resourced like a commercial business entity.

If not obvious by now, I was pounded in my corporate life to have SMART (Specific, Measurable, Achievable, Realistic, and Timely) goals.

 

[HammerSandwich]

Strikes me that there are conflicting goals in play. Sub-1kHz directivity, simple (not cardioid), large-room bass (not dipole), slim baffle... I probably still need more coffee today but don't see how to satisfy all of those at once.

 

[sarumbear]

While fantasizing is just fine, want to be clear that I do not have space for any monstrosities. For that matter, Amir would not be able to measure it either.

The r2 target should be something no more than the size of a Revel F206 for a floorstaander. Am still keep an open mind to a bass module, but thinking something the size of a B&W 801…

If it needs 250 watts or more to get decent bass output, am good with that too.

If you want high output at low frequencies, math shows us that you have three options.

1- Multiple medium size woofers. (8 or 10 inch). Like the Revel Salons.
2- A single large woofer (15 inch). Like most big JBL speakers.
3- Or use 12 inch subwoofer driver (with extra long Xmax) and cut it at a very low frequency (around 200-300Hz). Like B&W series.

Option 1 is simple but expensive. Option 2 requires a monstrous case. Option 3 demands an active design as matching driver sensitivity is not easy with a passive crossover.

 

[sarumbear]

Another vote for an active cardioid design here. I would like to see what can be done with affordable woofers and a decent tweeter like the SEAS from Directiva R1. After all the name Directiva was used because directivity is one of the key design principles right? I would love to hear something with controlled directivity down into the bass region but I can't afford the options from Genelec, Kii, or D&D. Something like the GGNTKT Model M1 would be awesome. I will DIY and scrounge to get the required electronics together.

It is not possible to have a cardioid design while using a dome/cone tweeter. High frequency sound waves will always be blocked by the enclosure.

 

[Rick Sykora]

If you want high output at low frequencies, math shows us that you have three options.

1- Multiple medium size woofers. (8 or 10 inch). Like the Revel Salons.
2- A single large woofer (15 inch). Like most big JBL speakers.
3- Or use 12 inch subwoofer driver (with extra long Xmax) and cut it at a very low frequency (around 200-300Hz). Like B&W series.

Option 1 is simple but expensive. Option 2 requires a monstrous case. Option 3 demands an active design as matching driver sensitivity is not easy with a passive crossover

As a rule of thumb, sure. Pick the Revel F208 if it helps. No absolutes at this stage. Still have to figure out what r2 will be.

 

[sarumbear]

Still have to figure out what r2 will be.

I was trying to help

I personally will go with option 1 as it is simpler. Not to mention has a good WAF.

 

[TimW]

It is not possible to have a cardioid design while using a dome/cone tweeter. High frequency sound waves will always be blocked by the enclosure.

I am probably confused about the terminology here, but I thought speakers like the D&D 8C, Kii Three and GGNTKT M1 were attempting to have a cardioid dispersion pattern down to the low mids/upper bass. That is what many of the websites claim at least.

 

[McFly]

I think they all use waveguided dome tweeters. I think @sarumbear meant regular old flush mounted domes, no waveguide

 

[abdo123]

If you want high output at low frequencies, math shows us that you have three options.

1- Multiple medium size woofers. (8 or 10 inch). Like the Revel Salons.

is it possible to have good control of directivity while having a + sign configuration ? (four woofers and a tweeter in the center of the +)

 

[Lbstyling]

So, have not put up the poll yet. If I had the cardiod idea would have not made it. I am a bit skeptical of the d&d 8c clone for a couple of reasons. Am not sure it meets the initial requirement for enough bass output for a large room (at 3-4 meter LP. Its woofer does not seem more capable than r1 and I know r1 would strain to energize solid bass in a large room. Am also not clear on how it might be extensible.

Am leaning towards slimmer bass module that is tall enough to be a stand for various types of monitor. I also liked the goal to get better directivity below 1 kHz. Anyway, grok on that a while as I will have limited online time for the rest of the week. We have a family wedding and will be hosting some family from out of town.

Cheers,

Rick

I think if we have a poll the wording would matter for cardioid in particular.

What proportion of the voters really understand what cardioid is, and what the theoretical advantages are?
If you posted the target aim rather than the tech used to get there you will get a different result. If you post a poll that says 'Aim: top the Spinorama', you will get considerably higher vote for it. Essentially, that is what cardioid would improve at the cost of SPL in the 100hz-300hz range for a given SD.

 

[sarumbear]

I am probably confused about the terminology here, but I thought speakers like the D&D 8C, Kii Three and GGNTKT M1 were attempting to have a cardioid dispersion pattern down to the low mids/upper bass. That is what many of the websites claim at least.

The wavelength at around 1000Hz is similar to the front baffle of a speaker. Above that frequency speaker sound is blocked by the baffle. Below that it gradually becomes omnidirectional.

As a speaker for music is expected to generate at least three and a half more octaves above 1000Hz, we can’t expect to achieve a speaker that has a cardioid emission format on most of its operating range.

 

[Lbstyling]

While we are spit-balling, not against the idea of an active/hybrid version of something like the Revel F208.

It could fit the extensibility goal by splitting the woofers into a bass module. No shame in doing something evolutionary...

Btw, Amir is too busy too support as much Klippel time as he did for r1, so this might factor into possible constraints on r2.

Nonsense. Lobbying is a community activity we can all get into

 

[abdo123]

we can’t expect to achieve a cardioid speaker.

i'm pretty sure the goal with the 3 designs mentioned is to have a forward firing speaker, not necessarily full-range cardioid.

 

[sarumbear]

is it possible to have good control of directivity while having a + sign configuration ? (four woofers and a tweeter in the center of the +)

What is + sign configuration?

 

[sarumbear]

I think they all use waveguided dome tweeters. I think @sarumbear meant regular old flush mounted domes, no waveguide

Not really. Waveguide or not. Cardioid pattern for the top three octaves of audio range is not possible.

Maybe I missed the context of your post?

 

[abdo123]

What is + sign configuration?