Hi,
Apologies in advance for coming at this the wrong way. I have a box, I do not yet have a driver. Basically I want to build a streamer into a nice box I found. So immediately we are not talking hi-fi here. But the box is pretty solid and I would like to get a decent sound out of it.
So can you good folks suggest a full-range driver that would work in a box of a little over 4 litres internal volume?
The internal dimensions are D 87mm x W 189mm x H 263mm. Yes, that's right, it is shallow (actually an attractive and solidly built presentation box for two bottles of wine!).
Considerations:
Tom
Apologies in advance for coming at this the wrong way. I have a box, I do not yet have a driver. Basically I want to build a streamer into a nice box I found. So immediately we are not talking hi-fi here. But the box is pretty solid and I would like to get a decent sound out of it.
So can you good folks suggest a full-range driver that would work in a box of a little over 4 litres internal volume?
The internal dimensions are D 87mm x W 189mm x H 263mm. Yes, that's right, it is shallow (actually an attractive and solidly built presentation box for two bottles of wine!).
Considerations:
- Cost: Looking to spend a few 10s of £s - I'm in the UK.
- Wide dispersion to fill the room as much as possible.
- Bedroom listening environment - low volume classical and spoken word mostly.
- Ported or sealed configuration.
- Shallow space - maybe two smaller drivers wired parallel would fit better. How nasty will this make the off-axis response?
- First thought was that I'm looking at a mono design, I guess there would be nasty intermod running stereo. But how about two drivers, driven in (software) mono by a stereo amp? A stereo dac+amp board is easier to source.
Tom
Hi! I'd do mono, single small full range driver in sealed box if no bass is required, very easy construct. There are many ~3" drivers available, I've only had Tymphany / Vifa / Peerless TC9FD18 but there are many others but this one is really cheap and good sound.
Highs will beam, you could add a tweeter if you wanted. A ~3" driver will have nice off-axis response something like 4kHz. If you use bigger driver they start beaming a bit lower frequency.
Another option would be to buy few more drivers, put them different sides of the box and do this: http://elias.altervista.org/html/SingleSpeakerStereo.html
Note, you can't use (at least most) class D amps for the connection scheme in the link but I believe a chip amp like lm3886 would do.
The single speaker stereo is a bit gimmicky but quite nice in a way, blows your socks of for cheap one hour hack! Mono is simplest though 🙂
Highs will beam, you could add a tweeter if you wanted. A ~3" driver will have nice off-axis response something like 4kHz. If you use bigger driver they start beaming a bit lower frequency.
Another option would be to buy few more drivers, put them different sides of the box and do this: http://elias.altervista.org/html/SingleSpeakerStereo.html
Note, you can't use (at least most) class D amps for the connection scheme in the link but I believe a chip amp like lm3886 would do.
The single speaker stereo is a bit gimmicky but quite nice in a way, blows your socks of for cheap one hour hack! Mono is simplest though 🙂
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Thank you and great link!
You've provided the simple answer but at the same time dangled a tempting worm in front of me leading to a whole can of worms!
I had been wondering about how to achieve any sort of stereo spread from a single box. There are plenty of upmarket one-box systems that do this but I'm sure they use signal processing techniques which I'm not ready to jump into yet. (It is fabulous to know that processor boards are available which would allow the hobbyist to get into it though - wonderful times we live in).
The author is obviously quite pleased with the results, there's undoubtedly going to be an unmeasurable psychoacoustic affect here caused by self-satisfaction but I'd hope to get a similar effect when I've finished my own build!
Of particular interest to me is that the author claims that by the time the real-world room effects are taken into account there is less appreciable comb filtering going on and that the speaker is hard to locate. This sounds like an advantage in my situation where placement is not going to be ideal and I'm less interested in accurate stereo reproduction and more interested in room-filling, with a more "alive" sound than mono.
So I'm nearly set on trying the 3 driver idea! The only thing holding me back is I'm worried that adding more drivers to a small box will further limit the bass response. I don't need big bass but neither do I want to further restrict those small drivers.
Also, forgive my ignorance but what is it about a class D amp that makes it unsuitable for this application? The chip amp you suggested would I'm sure sound lovely, but it requires more heat-sink than I could fit into the space I have.
Thanks again.
Tom
You've provided the simple answer but at the same time dangled a tempting worm in front of me leading to a whole can of worms!
I had been wondering about how to achieve any sort of stereo spread from a single box. There are plenty of upmarket one-box systems that do this but I'm sure they use signal processing techniques which I'm not ready to jump into yet. (It is fabulous to know that processor boards are available which would allow the hobbyist to get into it though - wonderful times we live in).
The author is obviously quite pleased with the results, there's undoubtedly going to be an unmeasurable psychoacoustic affect here caused by self-satisfaction but I'd hope to get a similar effect when I've finished my own build!
Of particular interest to me is that the author claims that by the time the real-world room effects are taken into account there is less appreciable comb filtering going on and that the speaker is hard to locate. This sounds like an advantage in my situation where placement is not going to be ideal and I'm less interested in accurate stereo reproduction and more interested in room-filling, with a more "alive" sound than mono.
So I'm nearly set on trying the 3 driver idea! The only thing holding me back is I'm worried that adding more drivers to a small box will further limit the bass response. I don't need big bass but neither do I want to further restrict those small drivers.
Also, forgive my ignorance but what is it about a class D amp that makes it unsuitable for this application? The chip amp you suggested would I'm sure sound lovely, but it requires more heat-sink than I could fit into the space I have.
Thanks again.
Tom
FWIW when stereo was rolled out in the '50s, Magnavox? added a factory stereo version to one of their larger mono consoles, putting the mids/HF speakers on each end with hinged doors to reflect off of and the centered OEM rear firing woofer was switched to a dual coil [DVC] one, relying on the gap to the wall to spread the summed mono LF.
To a then 11 yr old it sounded pretty cool, especially compared to their mono duo cone 15" Karlson K15 kit! 😉
To a then 11 yr old it sounded pretty cool, especially compared to their mono duo cone 15" Karlson K15 kit! 😉
Tom, yeah you should try it! You can make quick prototype to test the concept if you like it better to mono, possibly right now with no money involved! Use existing speakers you might have at home, arrange them backtoback to make the sides, and one as front (like the concept). If you have drivers put them into a cardboard box or anything that somewhat seals the back radiation of the drivers. Use any old stereo receiver/amplifier (class AB). If you are not impressed then you can just build a mono system and live happy with the decision 🙂
I tried it with three TC9, all on the same small karlson style box ( see the mini-karlsonator 0.4x size, thread by member XRK971), maybe litre or two volume on the box. I think the bass was similar (typical small speaker) with one or three drivers, not meaningfull difference. The thing is such a small speaker will inevitably sound small speaker no matter what the processing and stuff and there really is no stereo image unless you have two properly positioned speakers, a stereo system. So, in a way this is just fun variation to the usual small mono machine 🙂
The "stereo image" depends on your room wall materials and furniture and of course where the speaker is positioned. Nevertheless it gives a bit more spacious sound compared to mono and actually there is mono in the middle driver! The stereo image is kind of diffuse but the speaker nicely paints the complete wall with music if you have it middle of a wall. It is not perfect, but still very much fun.
If I remember correctly Class D amp is not suitable since the outputs are floating and grounds cannot be tied together. I haven't thought it through but something like this was mentioned on the forum. The author has thread on the single speaker stereo concept here on Diyaudio.com.
Stereophonic Sound from a Single Loudspeaker
edit. image of my hack proto here Toe in or Toe out for Boombox?
I tried it with three TC9, all on the same small karlson style box ( see the mini-karlsonator 0.4x size, thread by member XRK971), maybe litre or two volume on the box. I think the bass was similar (typical small speaker) with one or three drivers, not meaningfull difference. The thing is such a small speaker will inevitably sound small speaker no matter what the processing and stuff and there really is no stereo image unless you have two properly positioned speakers, a stereo system. So, in a way this is just fun variation to the usual small mono machine 🙂
The "stereo image" depends on your room wall materials and furniture and of course where the speaker is positioned. Nevertheless it gives a bit more spacious sound compared to mono and actually there is mono in the middle driver! The stereo image is kind of diffuse but the speaker nicely paints the complete wall with music if you have it middle of a wall. It is not perfect, but still very much fun.
If I remember correctly Class D amp is not suitable since the outputs are floating and grounds cannot be tied together. I haven't thought it through but something like this was mentioned on the forum. The author has thread on the single speaker stereo concept here on Diyaudio.com.
Stereophonic Sound from a Single Loudspeaker
edit. image of my hack proto here Toe in or Toe out for Boombox?
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I'm finding sourcing an amp tricky, so here's the plan: I'll order 3x 3.5inch full-range drivers, they are cheap enough and if I use just one then I'll have a pair for a future project. While they are on their way I'll try to find a common ground amp module that I can work with.