You would'n dare 
From a few minutes more.... there is definitely a need for side to side bracing in the chamber in FC - big fluctuation. The lower half is very stable.
There may also be a need for attenuation of the/a tweeter. I can hear clearly this thing was designed for a good balanced full range. The top end with this driver simply overpowers the good qualities of box.
More to come in the morning.....
From a few minutes more.... there is definitely a need for side to side bracing in the chamber in FC - big fluctuation. The lower half is very stable.
There may also be a need for attenuation of the/a tweeter. I can hear clearly this thing was designed for a good balanced full range. The top end with this driver simply overpowers the good qualities of box.
More to come in the morning.....
Nice work Bob! Congrats 
Try placing it with the mouth about 4 to 6 in from a wall - the sims show that makes a big difference. You can't compare this 5.25 in driver to the Vifa for mids and lows as it is only 3.5 in. I think a Cornu with this driver might surprise is all. I was not sure what you meant in your comparison with Cornu which has more bass? I forgot to remind you to add one good stick of foam across the chamber wall to brace the breathing mode. Did you put any stuffing in the thin channel?
Anyhow, thanks for being the trail blazer for this build.
Try placing it with the mouth about 4 to 6 in from a wall - the sims show that makes a big difference. You can't compare this 5.25 in driver to the Vifa for mids and lows as it is only 3.5 in. I think a Cornu with this driver might surprise is all. I was not sure what you meant in your comparison with Cornu which has more bass? I forgot to remind you to add one good stick of foam across the chamber wall to brace the breathing mode. Did you put any stuffing in the thin channel?
Anyhow, thanks for being the trail blazer for this build.
Geez Bob, that 'smilie' looks more scary than the October pumpkins I carve.You would'n dare
That's my favourite time too.
I'll do the room placement tomorrow.
The Cornu sounds bigger but I hear a lot more overtones/modulations that muddy up the bass when compared to DNA. As I said or tried to say, by the time you get the volume high enough to hear the qualities of the DNA, the rest of the signal is distorted. A better source may help.
I did put about a baseball size of very, very loose pillow stuffing in the first/top channel. The top also moves more than it should, so between that and the sides a significant amount of energy is being lost. I'm actually very surprised how much resistance the horn/path presents. Shows me just how careful one must be in insuring the expansion is uniform, accurate and unobstructed.
I thank you for leading on the design and look forward to some fine tuning.
Go to bed Cal !!
I should have known that this design provides a significant amount of horn loading on the driver. As the sims shoe that the driver excursion is well controlled meaning the pressure is being built up as it flows through channels. Sounds like copious bracing is in order for a foam build and with wood probably ok. You say too much higher freq comes from the driver. Isn't that he point - as this is supposed to be a full range driver? Or are you saying the high end on this driver is distorted? Based on the results of the sim, I am not surprised that the bass sounds cleaner than the Cornu. The Cornu sounds bigger than it is though.
Consider (cross) bracing the rear chamber and also the horn mouth.
Depending on the damping factor of your amp and your tastes, a few ohms in series with the driver may "fatten" up the bass to your liking.
Last edited:
Let me try to use a different set of words to describe. I have three good speaker designs that are all multi-driver. All have fairly sophisticated crossovers that keep the drivers working where they have an advantage. The Vifa and this driver, both being very low cost devices can't actually compete directly with the other system. I didn't have that expectation. No doubt single driver full range systems can do great things, but $6 or $12 drivers can't be expected to perform at the highest level.
My Vifa/Cornu combination is truly amazing considering the driver size and cost. To me, the DNA design had/has the potential to produce a different flavor and amount of bass, as well as equal and/or better sound in the other areas. The results I got are very similar to the difference between a sealed box and a reflex system - sort of a trade-off between accuracy and clean definition vs. more bass and not as much clarity. The DNA that I made definitely comes down on the acoustic suspension side. It would have been super if this driver exceeded my expectations for the top end, but from the get go I thought a separate tweeter would be needed. The low end was the attraction.
After sleeping on it, I'd have to say using FC here has several disadvantages. Even as a novice horn builder I can understand the need for tuning on a trial and error basis. Sealing the box makes that very difficult. Having a removable side panel seems absolutely necessary for that tuning process. The second problem is of course the breathing/fluctuation challenge. The amount of bracing necessary might in fact alter the calculations for the chamber. At a minimum, a "T" connecting the sides and top (through both top plates) is required. Using wood dowels might help reduce the number of braces but several would still be needed for good rigidity.
I'm anxious to hear about @struggles results with the wood cabinet. It might be best to get that version dialed in and then transfer what is learned to FC - maybe even 3/4". Again, I was very surprised at the power of the air column. If more energy makes it all the way to the mouth the high end might come back to better balance and less attenuation would be needed.
I'll do some more listening and tinkering and report back through the day....
My Vifa/Cornu combination is truly amazing considering the driver size and cost. To me, the DNA design had/has the potential to produce a different flavor and amount of bass, as well as equal and/or better sound in the other areas. The results I got are very similar to the difference between a sealed box and a reflex system - sort of a trade-off between accuracy and clean definition vs. more bass and not as much clarity. The DNA that I made definitely comes down on the acoustic suspension side. It would have been super if this driver exceeded my expectations for the top end, but from the get go I thought a separate tweeter would be needed. The low end was the attraction.
After sleeping on it, I'd have to say using FC here has several disadvantages. Even as a novice horn builder I can understand the need for tuning on a trial and error basis. Sealing the box makes that very difficult. Having a removable side panel seems absolutely necessary for that tuning process. The second problem is of course the breathing/fluctuation challenge. The amount of bracing necessary might in fact alter the calculations for the chamber. At a minimum, a "T" connecting the sides and top (through both top plates) is required. Using wood dowels might help reduce the number of braces but several would still be needed for good rigidity.
I'm anxious to hear about @struggles results with the wood cabinet. It might be best to get that version dialed in and then transfer what is learned to FC - maybe even 3/4". Again, I was very surprised at the power of the air column. If more energy makes it all the way to the mouth the high end might come back to better balance and less attenuation would be needed.
I'll do some more listening and tinkering and report back through the day....
Last edited:
Bob,
Thanks for the explanation. I am still not sure why you say that if the bracing were better, more power makes it out of the air column for the mouth and that might bring the high end back? The mouth only provides more bass if the flex were better controlled, and in fact, you would end up with even less apparent high end? I think it is the limitation of the NS525 driver not having a sufficient high end that may be bothering you. Once you add the tweeter with the 2 uF crossover, things should improve. Alternatively, the $13 MCM 5 in aluminum cone driver with a 17 kHZ high end may be a better choice for someone looking for a more balanced driver as a full range. A simple switch to that driver with a sack of 5 to 6 liters of volume-taking objects should work as the sims show a fairly nice response. Might be worth a try.
You can also cut a big window in the side of driver chamber and cover it with a thin sheet of plywood sealed with a ring of putty and held in place with screws with wood support on back side like driver. This will let you get inside and add bracing, change stuffing, and maybe make it easier to add tweeter. It looks like you kept space at the top for tweeter.
It will be nice to get an update from @struggles, hope he got his drivers and is testing them out.
Thanks for the explanation. I am still not sure why you say that if the bracing were better, more power makes it out of the air column for the mouth and that might bring the high end back? The mouth only provides more bass if the flex were better controlled, and in fact, you would end up with even less apparent high end? I think it is the limitation of the NS525 driver not having a sufficient high end that may be bothering you. Once you add the tweeter with the 2 uF crossover, things should improve. Alternatively, the $13 MCM 5 in aluminum cone driver with a 17 kHZ high end may be a better choice for someone looking for a more balanced driver as a full range. A simple switch to that driver with a sack of 5 to 6 liters of volume-taking objects should work as the sims show a fairly nice response. Might be worth a try.
You can also cut a big window in the side of driver chamber and cover it with a thin sheet of plywood sealed with a ring of putty and held in place with screws with wood support on back side like driver. This will let you get inside and add bracing, change stuffing, and maybe make it easier to add tweeter. It looks like you kept space at the top for tweeter.
It will be nice to get an update from @struggles, hope he got his drivers and is testing them out.
We are saying the same thing, except one of us is standing on their head - probablly me.
Less apparent high end compared to bass energy is what I called "balance". Yes, I see there are two paths to take: 1. dialing in performance of this driver and 2. Possible alternate driver.Since I have some extra/scrap wood around I'm going to build a small simple reflex box for this driver to help me get my bearings. Also, before I start the second DNA I need to make a few adjustments as I doubt my flair is as consistent as it should be. I'll go back to my original idea of mounting everything with double sided tape before using the hot glue.
Should have the tweeter and cap installed sometime this afternoon. I wasn't sure if the vertical placement was critical/related to the throat performance so I just guessed.
Have to catch up on all the household chores I've ignored since Sunday so most modding will be on pause for a while.
Last edited:
If you want less high end out of the NS525, maybe add BSC circuit like ~1.0 mH coil parallel with ~6 ohm resistor to tame some of that higher end? Once you add tweeter, won't your high end be even more pronounced and system will feel even more unbalanced? If not enough bass, it may mean this design doesn't have enough overall bass gain to negate need for BSC. ??? Ok, off to work now so I won't be posting until later today.
I guess you did!
Actually, @struggles said that he built his DNA from purchased plans. Why make out of FC? Mostly because it's easy to cut and doesn't need a power tool, although Bob sort of broke that spirit of doing things by running his carbide blade table saw to trim the boards... It's easy and cheap to do when you are not sure if the final result will be worth your time in real plywood. If it works in FC, it will probably sound even better in real wood. For some of us without a workshop or powertools, the FC will have to suffice to be our final listening product.
Have you actually read the whole thread? Some of us have bought the plans.
Regards
I was going to do a quick sketchup model of this but am having trouble reconciling the dimensions.
I took the jpg that was posted, and re-sized it. It was not to scale as shown nor proportional, btw.
You can see how I traced the resized drawing with a CAD program. Then I imported into Sketchup to have it show the dimensions. Some of dimensions are close, some are way off.
Help!
I took the jpg that was posted, and re-sized it. It was not to scale as shown nor proportional, btw.
You can see how I traced the resized drawing with a CAD program. Then I imported into Sketchup to have it show the dimensions. Some of dimensions are close, some are way off.
Help!
