Yes this is the message of us all, right, at least I read the posts so. Its just that the baffle needs to approach room wall size in order to get rid of the effects, blend diffraction with the room reflections. The other end is to blend diffraction with the transducer direct sound making the baffle as small as possible. Or blend into nothing by removing the edge with big enough roundover. 😉 Minimal baffle is most practical, but of course any one of the methods works the same. Difference on all these is resulting directivity which is mostly about the size of the construct.
Very true. Take Buchard Audio or YG acoustic, a perfect example, smooth Mid to Tw transition. Its said: "All horns are waveguides but not all waveguides are horns".
Yes it seems logical there would be some thresholds frequency region where such bad transition would be bad, also how severe the jump in DI / dip in power is.
Kimmosto talks about something along the lines in ASR lately https://www.audiosciencereview.com/forum/index.php?threads/neumann-kh150.33454/post-1361757 which I interpret to relate to this discussion as well, and observations you have to various systems. "Signature of ways", hah, inventing terms here, if there is multiple per speaker and they differ too much it makes the sound less good, less homogenous, less integrated, I think. Besides issues with having various sized transducers with various physical properties and signatures, directivity, distortion, we have a structure that varies in size of course, also diffraction of each transducer is different in signature. Well, fun stuff.
Kimmosto talks about something along the lines in ASR lately https://www.audiosciencereview.com/forum/index.php?threads/neumann-kh150.33454/post-1361757 which I interpret to relate to this discussion as well, and observations you have to various systems. "Signature of ways", hah, inventing terms here, if there is multiple per speaker and they differ too much it makes the sound less good, less homogenous, less integrated, I think. Besides issues with having various sized transducers with various physical properties and signatures, directivity, distortion, we have a structure that varies in size of course, also diffraction of each transducer is different in signature. Well, fun stuff.
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I remember T Gravsen input about the Stradivari loudspeaker cone: soundstage is better with tiny width baffle or unusal large width smooth recess baffle.
I assume infinite baffle is what we'd like. Illustration is ScanSpeak measure their driver with 6x6 m baffle.
I assume you like too the room corner loaded because the walls makes the 90° baffle ?
Absolutely and I do agree with Kimmosto for the most part and like I mentioned, not all waveguides are bad. I am far from an expert here and there are far too many variables IRL vs all the theoretical stuff we are talking about and using here or in any online debate forum, but there are certain stuff that either makes perfect sense (after a while) or just plain sound good. But we are going to end up banging our heads against the wall anyway since we all hear a bit different. We are sensitive to various issues to a varying degree, and so forth. But I know I enjoy the soundstage and imaging a relatively narrow, well executed, baffle. But that is only a faction of the equation since the driver itself and XO implementation is missing here.
Look at this:
"Most studies show that the maximum jaw range of motion (ROM) or maximum mouth opening (MMO) is related to body size and height. So men can usually open wider than women, taller people more than shorter people. In studies, MMO for adults has generally been around 50 mm, with a range from 32mm to 77mm. Men can open to about 50-60, and women to 45-55mm." source
3" is equal to 76.2mm
Going beyond 5-5½ is usually not wise when it comes to the human voice since the projection body is larger than the average sized mouth. Therefore, going 4-way is almost a must if one wants to have a good instrumental projection and balanced performance of true to life.
Someone who stands out, as a driver engineer and producer is Stanislav Malikov of BlieSMa. His tweeters and midranges might be among the better out there. So besides a well executed Planar Magnetic Driver, which I am currently studying, I would bet my money on BlieSMa. It is on my short list and might push the trigger on his stuff so that I can compare it to planars.
Read these articles.
Midrange: https://hificompass.com/en/reviews/bliesma-m74a-6-m74b-6-m74p-6-and-m74s-6
Tweeter: https://hificompass.com/en/reviews/bliesma-t25a-6-t25b-6-t25d-6-t25s-6
Can you elaborate more on this? What would you consider to be "large" for a baffle?
Also just asking to everyone....... it seems like Qts isn't as important of a parameter for an OB bass driver as I thought. What parameters should one be looking at for good LFE and overall response for an OB bass driver?
cheapvega. This was debated moments ago if you scroll up a bit, some of the negative aspects is when diffraction happens and the direct sound projection which often favour midrange frequency's and hence, a relatively large flat baffle tend to sound midrange hot. So far, a large baffle have not convinced me in terms of proper or somewhat realistic soundstage. Also something which was talked about earlier in the thread. There might be an exception with the Sonus Faber Strad's
Besides BlieSMa, Purifi is another state of the art manufacturer and their 6,5" Alu woofer is being well received with very low IMD and overall low distortion. The radiating area (cone + 2 x ½ suspension) is equal to roughly 146mm and 5.7". Purifi also launched an 8" which looks rather decent. PTT8.0X04-NAB-02 looks to have an F3 of 65Hz and F6 at 50Hz (speculative). With two in RiPole config (DRS-RiPole), 25Hz could reach something like 78dB and the Fs lowered to less than 16-18Hz, so an easy load on the amplifier.
It would be quite possible to build a 4-way with excellent metal drivers these days, aka, without sibilance or tinny sounding like in the past. Absolute phase crossover and acoustically smooth cabinet .. yeah baby yeah... LOL
1. https://hificompass.com/en/reviews/purifi-ptt65x04-naa-08-65-alu-midwoofer
2. https://purifi-audio.com/ptt8-0x04-nab-02/
It would be quite possible to build a 4-way with excellent metal drivers these days, aka, without sibilance or tinny sounding like in the past. Absolute phase crossover and acoustically smooth cabinet .. yeah baby yeah... LOL
1. https://hificompass.com/en/reviews/purifi-ptt65x04-naa-08-65-alu-midwoofer
2. https://purifi-audio.com/ptt8-0x04-nab-02/
I know it seems logical to use a room corner so you can get more baffle using the walls to help, however not as much as you think. You usually try to avoid this because there is a step, unless you build the speakers into a hole in the wall... In any case you still design to achieve quarter space radiation.
Regardless of this, the quarter space radiation fits better into a room for reduced reflections and longer reflection free time. There is no perfect shape to make a speaker to fit a room correctly, but with help from what we know about acoustics we can do it well.
OK, looking into it it seems like going for a low Fs + high Qts is the way to go for OB LFE. Linkwitz transform just seems to be a Qts boosting filter. My system is battery powered so the less low end EQ I can use the better.
A vented is what makes the coil moves the less if battery is higher on your trade off list. I do not know if a 18" with a 30/35 hz Fs could avoid an electrical bass boot in OB...certainly baffle size dependant. H frame should help you with some sacrifice on the driver efficienty but helps to make the cab rinnier so movable for your use. If it is for outside you will not have bass boost from a room.
Somewhere guitar cab speaker is at leat a U frame already. So'old reciep.
Somewhere guitar cab speaker is at leat a U frame already. So'old reciep.
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as diydiggy tell ,you cannot low more the 35hz in H frame ,OB is joy not number
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
It took me a few reads to understand what you said but I think I got it.
System I'm building is replacing a PE Executive boom box so that's the level of portability I'm pursuing. I.e. no 18s (believe me I have been scrambling and scraping to find a reason to build around some GW-1858s but haven't found one yet)
Driver I settled on was the GW-212/4 x 2. Lowish Fs & high Qts (low 30s and 1.2 IIRC). Efficiency is not great but everything is relative. The single W5 + PR in the PE box models at about 80dB in the bass frequency range. A single GW-212/4 in a 1.5x2' baffle extends lower, has a less steep rolloff and is about 5dB more efficient. Add another 3dB since I will be running 2 channels. Hoping the model matches... I'm actually happy with the bass from the PE box but not the narrow soundstage.
Anyways regarding Qts the Quarter-wave paper said higher is generally better, reinforcing how a lower Qts = gentler rolloff but a higher F3. Just thinking about how Q affects filters visually this makes sense I guess.
@nicoch58 35Hz is fine with me; I mainly listen to funk and jazz so that def covers my bandwidth.