Once again, everybody rushing to provide their favourite solutions without taking care about knowing the problem or the requirements.
I think the key to understanding OP's sound quality goal is OP's statement, "...(normally do musical instrument diy)...". I have a feeling we need to think about Toole's emphasis on ambience as a sonic feature.
All this talk about 3D imaging is kind of like the old advertising joke, "... these headphone have great separation...".
B.
I think the key to understanding OP's sound quality goal is OP's statement, "...(normally do musical instrument diy)...". I have a feeling we need to think about Toole's emphasis on ambience as a sonic feature.
All this talk about 3D imaging is kind of like the old advertising joke, "... these headphone have great separation...".
B.
And open baffles can be surprisingly good at creating the illusion of depth.
I know this from having OB speakers in a lava cave.
Since the OP states:
And this made me think of large baffles and large woofers.
I know this from having OB speakers in a lava cave.
Since the OP states:
This would be a good space for any speakers, and a place where OB would work particularly well.
And this made me think of large baffles and large woofers.
For me only large speakers achieve a realistic rendition of a orchestral music. With OB in a great space, even mono recordings have realistic depth and scale, making them quite enjoyable. OB isn't the only way to go, but I think it would be well adapted in this instance.
Speed?
I have always found the "speed" thing amusing. Especially in regard to woofers. What we really need to talk about is resolution. A woofer will tend to provide its best resolution in a free air, or near free air environment or under a lot of load, i.e., horn. They tend to yield poorer resolution in a ported box due to box interior interaction. Reflections, ringing due to improper tuning, enclosure resonances and so on. Plus group delay issues. A well executed sealed box and or infinite baffle can work well when the QTC is at or above 0.8 or so. As is usually the case, better resolution comes down to proper utilization.
I have always found the "speed" thing amusing. Especially in regard to woofers. What we really need to talk about is resolution. A woofer will tend to provide its best resolution in a free air, or near free air environment or under a lot of load, i.e., horn. They tend to yield poorer resolution in a ported box due to box interior interaction. Reflections, ringing due to improper tuning, enclosure resonances and so on. Plus group delay issues. A well executed sealed box and or infinite baffle can work well when the QTC is at or above 0.8 or so. As is usually the case, better resolution comes down to proper utilization.
This is my experience too and it's been with a simple OB, ie, not good dipole so I don't put it down to the directivity, I believe it's due to the reflection from the front wall.
Large baffles can get in the way of the reflection and possibly cause multiple reflections.
Me too thinks OB dipoles give good depth (and good localization too). A moment's thought will reveal that to be ironic that a great mush of ambient sound is better than a point-source. But I think it indicates that a lot of "depth" is created by the brain, not the speaker.
B.
B.
If the cabinet lacks internal treatment, that's poor implementation. In the same way, poorly implemented horns or OBs also sound bad.
A ported box can have identical group delay to a sealed box. Despite the mechanics, they're both minimum-phase systems where the phase response is a function of the frequency response. ie, if you EQ the sealed box to match the ported box, the phase curves (and therefore group delay) will be identical.
Qtc >0.8 indicates ringing.
Chris
JohnK says (and shows the math) that a Q of 1 is correct for the bass. Anything else is over-damped.
Of course a lot of things happen between the cone and the ear to raise the overall Q. Meaning that if your target is Q=1 in the room, you need to start out lower than that.
Of course a lot of things happen between the cone and the ear to raise the overall Q. Meaning that if your target is Q=1 in the room, you need to start out lower than that.
Hi,
Open baffles are one of the most satisfying sound system there is however, please note there are many different type of open baffles.
1) True open baffles - woofers and mids are open baffles. Tweeter may or may not be open baffles (only some ribbons are open back).. electronics require very heavy tweaking for bass and you really must understand what you are doing. Typically you need to cross before the amps and you require biamping. You also need to figure out how to implement a 10-20 db bass boost as the back wave cancels the front at low frequency. A simple RC filter can do the trick.
2. Semi open baffle. Only mids(full range) and/or tweeter is open baffle. Bass is normal. Example, linkwitz stuff, Nola speakers etc. You can use a more conventional design. Can be significantly smaller and look like normal speakers. But you need to be careful that the lower frequency of the baffle is within the crossover.
All in all, the open baffle is a very satisfying system. But if you are building speakers for the first time, I am not sure if I would recommend it to you. You should have some sufficient knowledge of electronics and implementation of audio systems. In other words, do it if you intend to take up DIY speakers as a hobby, but not if you are doing it as a one time off project.
The bass of the true open baffle is the fastest of all speakers. The woofer stopping effect is small compared to room effect. Open baffles have a very focused bass and it only happens in the front. There is no bass coming off the sides. Hence the decay of bass in the room is the fastest.
Oon
Open baffles are one of the most satisfying sound system there is however, please note there are many different type of open baffles.
1) True open baffles - woofers and mids are open baffles. Tweeter may or may not be open baffles (only some ribbons are open back).. electronics require very heavy tweaking for bass and you really must understand what you are doing. Typically you need to cross before the amps and you require biamping. You also need to figure out how to implement a 10-20 db bass boost as the back wave cancels the front at low frequency. A simple RC filter can do the trick.
2. Semi open baffle. Only mids(full range) and/or tweeter is open baffle. Bass is normal. Example, linkwitz stuff, Nola speakers etc. You can use a more conventional design. Can be significantly smaller and look like normal speakers. But you need to be careful that the lower frequency of the baffle is within the crossover.
All in all, the open baffle is a very satisfying system. But if you are building speakers for the first time, I am not sure if I would recommend it to you. You should have some sufficient knowledge of electronics and implementation of audio systems. In other words, do it if you intend to take up DIY speakers as a hobby, but not if you are doing it as a one time off project.
The bass of the true open baffle is the fastest of all speakers. The woofer stopping effect is small compared to room effect. Open baffles have a very focused bass and it only happens in the front. There is no bass coming off the sides. Hence the decay of bass in the room is the fastest.
Oon
I like your treatise.
Unfortunately the issue I see is the way some interpret the conclusions. Particularly the idea that it isn't fast enough. Of course, on a response plot it can be seen that for a certain Voltage drive it will respond for a certain level of output. More in equals more out.
What may be important then is shown by the way the driver responds with all other frequencies. In two cases where the same input/output relationship exists.. is this one frequency down somewhere along a rolloff out of the driver's passband, or is it in the passband of a driver that has a much lower sensitivity?
I feel as though open-ended questions like these should start with answering some boilerplate questions:
1) Listening distance?
2) Will there only ever be 1 person who is doing critical listening?
3) How much moving around will the listener(s) do?
4) What average SPL (at the listening position) is expected?
5) What peak SPL capability (at the listening position) is required?
6) What are the dimensions of the room?
7) What are the materials & methods for the room construction, including devices for absorption, resonance, and diffraction?
8) Are there any asymmetries to the room?
9) Can a standard equilateral / isoceles setup be accommodated?
10) What are the possible ranges of distance from speaker to side wall and to back wall?
11) What is the budget?
12) Is there a limitation on available power (amplification)?
13) Is SAF or general aesthetics a consideration?
1) Listening distance?
2) Will there only ever be 1 person who is doing critical listening?
3) How much moving around will the listener(s) do?
4) What average SPL (at the listening position) is expected?
5) What peak SPL capability (at the listening position) is required?
6) What are the dimensions of the room?
7) What are the materials & methods for the room construction, including devices for absorption, resonance, and diffraction?
8) Are there any asymmetries to the room?
9) Can a standard equilateral / isoceles setup be accommodated?
10) What are the possible ranges of distance from speaker to side wall and to back wall?
11) What is the budget?
12) Is there a limitation on available power (amplification)?
13) Is SAF or general aesthetics a consideration?
Can you explain in another way? I'm not sure I understand the meaning of the question but am interested in this line of thought.
At a given frequency, mass, motor strength and other concerns might conspire to cause a certain output level for a given input. Say for arguments sake that this is lower in level than the primary passband due to rolloff. This doesn't mean that it is going to sound sluggish when doing so.
Therefore to some degree an out of band reduction in level could be equalised and sound right. Now, on the other hand equalising deeply to compensate for a natural rolloff could mean the driver (or system) is being pushed into use where it isn't optimum.
Depending on the cause, take two different configurations, each which gives say 80dB/SPL at 1kHz, so the same capability per input. If one has a passband that is at 95dB but rolls off to 80dB at 1kHz you'd be inclined to think about the reason why it is rolled off before trying to EQ 1kHz back up by 15dB. However in the second case, if the entire passband were at 80dB naturally, there is less reason to question whether it is appropriate to use it at that frequency. Aside from the usual questions you'd simply do it (there's no expectation for it to sound sluggish).
Hi,
a passive OB is doable, but not exactly easy. If you´ve never done it all by yourself, you might start with a relatively simple and cheap kit, as these perhaps: Power-Duo (no connection nor affiliation - just as an example). If you like them, go on from there.
Please keep in mind that passive OB will never have a good efficiency in the bass region, so overall loudness with a 20-watter will not be very high.
All the best
Mattes
a passive OB is doable, but not exactly easy. If you´ve never done it all by yourself, you might start with a relatively simple and cheap kit, as these perhaps: Power-Duo (no connection nor affiliation - just as an example). If you like them, go on from there.
Please keep in mind that passive OB will never have a good efficiency in the bass region, so overall loudness with a 20-watter will not be very high.
All the best
Mattes
It's good to know others are finding satisfaction with that setup. I, too, am running 8 inch (two/side) drivers with 1" compression driver crossed over at 1kHz, via active crossover.
IME, it's much easier to come up with great sound with such 2-way horn system (controlled directivity) in most rooms compared to OB, not to mention the freedom to use high-quality, low-power amps.
That's very true. But neither will an active OB have good efficiency. You are either attenuating the mids and highs (passive), or boosting the low end (active). Either way, it's the low end that is the limit and you need the same voltage levels. There is no free lunch.
OB crossovers can be confusing if you are used to typical box crossovers. Once you understand them, they aren't any worse than anything else.
Right, the efficiency is really just based on the driver's efficiency in an IB (for the most part) plus the impact of the OB. The decrease in sensitivity from passive filtering is not necessarily a real decrease in efficiency (e.g. the amount of amp power lost as heat in the filters).