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The design is now finalized and deserved of a properly titled thread
[contd. from : https://www.diyaudio.com/community/threads/sub-1-large-or-2-small-drivers.138442/]
For those who don't know, this project is part of my attempt at assembling a HT system. The surrounds were done already [see: http://www.diyaudio.com/forums/showthread.php?s=&threadid=138195] and now we have the matching sub.
The theme is Forbidden Planet and the sub is named after the planet they landed on.
[contd. from : https://www.diyaudio.com/community/threads/sub-1-large-or-2-small-drivers.138442/]
For those who don't know, this project is part of my attempt at assembling a HT system. The surrounds were done already [see: http://www.diyaudio.com/forums/showthread.php?s=&threadid=138195] and now we have the matching sub.
The theme is Forbidden Planet and the sub is named after the planet they landed on.
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The box pretty much finished. Varnished and painted waiting for drivers and plate-amp to be installed. The design provides for a hollow tunnel through the box between the drivers. This is perhaps an unusual arrangement for bracing. However, it makes assembly and other tasks very much easier and I highly commend this approach.
I have assembled the drivers and amp temporarily and applied power - and heard some low frequencies....
this is a good moment to thank all those who have provided advice (Dave of planet10, Moondog55 and others)
I have assembled the drivers and amp temporarily and applied power - and heard some low frequencies....
this is a good moment to thank all those who have provided advice (Dave of planet10, Moondog55 and others)
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It's been breaking in and sounding nice, ti really fills out the low end for the Moon-Onkens nicely - but the plate amp is not screwed into the box yet so it isn't exactly 'sealed'. I hope this weekend to remove the drivers, tidy up the soldering of the wires to the drivers and finish it all up. Then I'll be able to update my impressions.
p.s. Not having had a sub before I was still surprised (despite warnings) how much the bass gets localized in and around the house.
p.s. Not having had a sub before I was still surprised (despite warnings) how much the bass gets localized in and around the house.
Bigun said:
This is why it is much better to invest in 3 or 4 smaller subs than one large one. Uneven low frequency response is inherent for indoor small-room listening.
http://www.mehlau.net/audio/multisub_geddes/
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No doubt several subs have their advantage, but after making all the surounds I didn't want to make several subs. One is enough in terms of effort and I'm prepared to take some time to optimize the setup I have.
There are many variables involved even with one sub, optimization with many subs adds to the complexity. reduces WAF, can add to the cost. I leave that avenue for others to explore.
In fact, my speaker making days may be winding down now. Having made what I need in the way of speakers I am busy soaking up knowledge about amplifiers...
There are many variables involved even with one sub, optimization with many subs adds to the complexity. reduces WAF, can add to the cost. I leave that avenue for others to explore.
In fact, my speaker making days may be winding down now. Having made what I need in the way of speakers I am busy soaking up knowledge about amplifiers...
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It was my understanding that there are supposed to be nuts on both sides of the baffle on the the threaded rod so it acts like a rigid brace in both push and pull action. Your first pic shows no nuts on the inside of the baffle, is this how you are running it or did you put nuts in there? It looks great, like a fine piece of furniture.
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901 Fixer and Dave,
I didn't have nuts on there at first whilst I did a 'dry fit' but you sure need them during assembly to stop the rods moving around. I don't believe they provide very much mechanical rigidity in my case as these rods are just too long for their thickness to put under very much compression. This is where the birch ply bracing comes in to play, the internal bracing is substantial between the baffles and way way stronger than the rods. Also, by no putting any cross bracing within the 'tunnel' that runs from one baffle opening to the other it really helps with construction as it provides much needed access to the interior. I assembled 5 sides pretty quickly then installed major bracing, then closed the box with the 6th side. A lot of stuff could still be worked on through the baffle openings and amp cut out.
Martin,
I'd be glad to shed more light on any specific areas of interest (do also feel free to email as I don't get into this forum often now that I'm learning how to design amplifiers). Overall it was quite satisfying. I don't like to build from kits or copy existing designs 100%, it doesn't leave enough scope for me or force me to learn about what I'm doing. It also gives you a chance to ask lots of really smart people on this forum for much needed help which makes it a whole lot more fun that doing it alone. For the Moon-Onken satellite speakers I did a lot of learning having never heard of speaker DIY until a few weeks ago. The sub was therefore another opportunity to learn. Even the plate amp being Class D was something I wanted to know how it worked.
I wouldn't want to build a larger box that this. There's a helluva lot of convenience in being able to readily man-handle the box, clamp it and work with it on a bench. I really like the push-pull design approach, it's not so run-of-the mill and I think it looks very cool when finished providing that the inverted driver is recessed into the box as I have done. It's also worth NOT mounting the regular driver flush but using a double-thickness baffle allow it to sit on the inner sheet. The reason is that the inside lip of the larger circular openings in the baffles of both drivers make perfect hand grips for moving it around - without which it would be very awkward.
Sound is good, not a big bang kind of sub but integrates very nicely indeed with the Onkens and without any real effort.
G.
I didn't have nuts on there at first whilst I did a 'dry fit' but you sure need them during assembly to stop the rods moving around. I don't believe they provide very much mechanical rigidity in my case as these rods are just too long for their thickness to put under very much compression. This is where the birch ply bracing comes in to play, the internal bracing is substantial between the baffles and way way stronger than the rods. Also, by no putting any cross bracing within the 'tunnel' that runs from one baffle opening to the other it really helps with construction as it provides much needed access to the interior. I assembled 5 sides pretty quickly then installed major bracing, then closed the box with the 6th side. A lot of stuff could still be worked on through the baffle openings and amp cut out.
Martin,
I'd be glad to shed more light on any specific areas of interest (do also feel free to email as I don't get into this forum often now that I'm learning how to design amplifiers). Overall it was quite satisfying. I don't like to build from kits or copy existing designs 100%, it doesn't leave enough scope for me or force me to learn about what I'm doing. It also gives you a chance to ask lots of really smart people on this forum for much needed help which makes it a whole lot more fun that doing it alone. For the Moon-Onken satellite speakers I did a lot of learning having never heard of speaker DIY until a few weeks ago. The sub was therefore another opportunity to learn. Even the plate amp being Class D was something I wanted to know how it worked.
I wouldn't want to build a larger box that this. There's a helluva lot of convenience in being able to readily man-handle the box, clamp it and work with it on a bench. I really like the push-pull design approach, it's not so run-of-the mill and I think it looks very cool when finished providing that the inverted driver is recessed into the box as I have done. It's also worth NOT mounting the regular driver flush but using a double-thickness baffle allow it to sit on the inner sheet. The reason is that the inside lip of the larger circular openings in the baffles of both drivers make perfect hand grips for moving it around - without which it would be very awkward.
Sound is good, not a big bang kind of sub but integrates very nicely indeed with the Onkens and without any real effort.
G.
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