Viva la Vifa DCR No. 2 Completed
The second unit has been built and tested. They sound very nice in stereo and they measure very nicely too. Here are some measurements at reduced levels representative of how I would listen to them in stereo. The distortion is way down and relatively flat from 50 Hz to 20 kHz.
Here is the SPL vs Freq over different approximate polar angles ranging from 0 deg to 45 deg for both speakers:
At first I was not getting as much bass extension from the second unit so I rebalanced it by reducing some stuffing in the upper chamber and both speakers now measure pretty closely (green is new trace after rebalance - compared to maroon):
Harmonic Distortion of DCR #1 at typical listening levels:
Harmonic Distortion of DCR #2 at typical listening levels:
Impulse Response for DCR #1:
Impusle Response for DCR #2:
The second unit has been built and tested. They sound very nice in stereo and they measure very nicely too. Here are some measurements at reduced levels representative of how I would listen to them in stereo. The distortion is way down and relatively flat from 50 Hz to 20 kHz.
Here is the SPL vs Freq over different approximate polar angles ranging from 0 deg to 45 deg for both speakers:
At first I was not getting as much bass extension from the second unit so I rebalanced it by reducing some stuffing in the upper chamber and both speakers now measure pretty closely (green is new trace after rebalance - compared to maroon):
Harmonic Distortion of DCR #1 at typical listening levels:
Harmonic Distortion of DCR #2 at typical listening levels:
Impulse Response for DCR #1:
Impusle Response for DCR #2:
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Design is very beautiful, I do drum sound box, over 1 years. Recently to play full frequency, hope and you communicate.
Wuxinghui2013,
Thank you! I am listening to these speakers right now as I type - they make fantastic office computer speakers. The bass is so full and rich even at low volumes my friends think that I have hidden a sub woofer hidden under the desk. 🙂
What do you mean by "drum sound box"? That the walls of the enclosure also contribute by passive radiation like a cello or guitar body?
Thank you! I am listening to these speakers right now as I type - they make fantastic office computer speakers. The bass is so full and rich even at low volumes my friends think that I have hidden a sub woofer hidden under the desk. 🙂
What do you mean by "drum sound box"? That the walls of the enclosure also contribute by passive radiation like a cello or guitar body?
I see what you have is what we call a tapered transmission line (TL) speaker with a non rectangular cross section - it will make the folded paths vary in cross section for an interesting effect.
The closest thing to this with a TC9FD that I have done would be this:
http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures-109.html#post3335376
But I think you might like the mini Karlsonator - which has unanimous good reports from many builders.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds.html
The closest thing to this with a TC9FD that I have done would be this:
http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures-109.html#post3335376
But I think you might like the mini Karlsonator - which has unanimous good reports from many builders.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds.html
Halair,
I know you have been busy with your line array but were you still thinking of building this? I have been using it in my office and it is amazing how deep and rich the bass sounds at low volumes. I think a lot may have to do with using it in a small office where room effects really boost the bass. I can't turn it up loud at work but there is no shortage of bass - I am powering with a Sure TPA3110D2 amp. Tin Pan Alley by SRV sounds really amazing on this speaker.
Oh yeah, I have every intention do do a pair when I'm done with the arrays 🙂
I am also inclined to try with a higher end amp, they can come stupid cheap on the 2nd hand market if found "small" enough 😉
I have no intention to use foam for the build btw... 😉
I am also inclined to try with a higher end amp, they can come stupid cheap on the 2nd hand market if found "small" enough 😉
I have no intention to use foam for the build btw... 😉
Halair,
If making out of wood, do you intend to make curvy walls? Part of the sound is due to curvy walls which doesn't support resonance modes as easily as flat parallel wall box.
If making out of wood, do you intend to make curvy walls? Part of the sound is due to curvy walls which doesn't support resonance modes as easily as flat parallel wall box.
Yes, combine your design and reflex chambers into a Vifa MagicoMini package. I would like to try wesayso´s construction method for his TT´s as a basis. 😀
X - I was at my local wood yard yesterday picking up a sand box for the kids, walked by a nice plate of MDF that was being used as a pallet divider. Asked the clerk what they did with those once the pallet was emptied. "We keep a couple, throw away the rest". Can I have a couple? "Sure!" Thank you!
So now I have two really nice MDF boards, 3/4" x 35" x 46"
Kerfing or translam DCR?? To be determined...
So now I have two really nice MDF boards, 3/4" x 35" x 46"
Kerfing or translam DCR?? To be determined...
No, that is not to scale. I have the template somewhere but the key thing to do is make the front flat as wide as you need to mount the driver, I think I used 4in. I made the main body 6in wide at its widest point. The rest self formed curves to follow the flat front to the 6in wide and then tapering towards the tail width. I don't have the speakers anymore, Byrtt has them so he can probably get a measurement for you.
When you are thinking about the width of the baffle, while it clearly needs to include the width of the driver, at what point do you consider the effects of the baffle on the lower registers? Not being very sophisticated myself, I wonder how people with more expertise think about this issue. Aesthetically, I prefer a narrow front profile most of the time. But it is my understanding that this reduces the volume of the lower registers.
So, when does this become a relevant issue in design?
So, when does this become a relevant issue in design?
Here is a photo of the BSC circuit:
Hi X,
What is the value of the capacitor you've used here?
I think it was 2.2uF but you can adjust to taste. I recently found that cheap ferrite core PCB inductors work well for full range BSC's. These cost about $0.60 ea and are 1mH and can probanly handle 1.5amps. No need to spend $14 on an air core 18ga.
What's the dimensions if you want to do a rectangular version of the DCR? I don't have the skill with foam to do the curves yet.
Erknie,
In X's first post on this thread he mentions the total volume of the cabinet being 12.5 liters, with 2/3 going in the top chamber and 1/3 of that volume allocated for the bottom chamber. Roughly, the internal dimensions of upper chamber can be 8.5" x 10" x 6", and other part 4.25" x 10" x 6".
In X's first post on this thread he mentions the total volume of the cabinet being 12.5 liters, with 2/3 going in the top chamber and 1/3 of that volume allocated for the bottom chamber. Roughly, the internal dimensions of upper chamber can be 8.5" x 10" x 6", and other part 4.25" x 10" x 6".
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That's the correct approach - go by volumes and set whatever cabinet size you need keeping in mind need to fit driver width and need for vent to be contained internally. Also, the wider the baffle or closer to a wall that you use the speaker, the less BSC you will need.
