Bottlehead Forum
Other Gear => Speakers => Topic started by: 4krow on April 11, 2015, 02:23:53 PM
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Hey guys,
I have started a project with a pair of Audio Nirvana 12" full range drivers. They haven't been released by David Dicks, owner of AN, and are a prototype driver. Given this, I won't say too much about them, but here is a couple of photos of the build. I have chosen a 4 cu. ft. cabinet design, slanted part of the front baffle, and will use a slot instead of a port hole. If the slot isn't satisfactory, then I will try a port hole w/o tube, as recommended by the designer. I will post more later, but this will give you an idea of the project.
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Found one more photo.
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Nice work. When did David Dicks say the speakers would be ready? Since He already has alnico, ferrite, and neo magnet speakers would His new speaker be a field coil?
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Hey 4krow! Those are looking really nice. Looking forward to more updates.
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Thanks guys! It's been awhile since I posted here. Figured that you might get a kick out of these. Chard, It would be really cool if these were field coil. but no, they are just a larger version of the Classic series. I can say that since they will be out pretty soon. I would have liked the alnico or even neo models, but the price was out of range for me. I figured that I could get a taste of what these were all about by at least going mid line. More to come.
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Gettin' there. The rest of the needed damping will be put in place after the bottom baffle is glued on.
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I got this far today for just one speaker, but this is the general idea.
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Yah, I just had to install the driver and take it for a listen. More about that tomm.
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Greg,
It looks nice! Where did you get the facing you used? What is that in front of the speaker when you are testing?
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G,
At the moment, it looks better than it sounds. To me, break in is a big part for these drivers. As for the material used, I tried to recycle as much as I could find. In this case, I had sizable wood scraps from years ago. The front baffle is made from former workbenches to former kitchen counter tops. All solid wood, but two different thicknesses. More work than you think went into gluing pieces together. There is very little scrap left behind.
Now to the performance of the driver so far. To start the break in, I am using a cheap class D amp, and an old yamaha music server. I expected this to be a good combination, yet there seems to be a sizable amount of distortion. Really, I can't tell if this has something to do with the driver or the source combination. The driver sounded so sharp and forward that I am using a device from Decware Audio. It is meant to help tame some of the issues that I described above. It is a particularly sensitive device that is adjustable. The idea is that the secondary winding of this transformer can have a load applied to it causing a reaction of taking a bit of the 'zing' from the driver it is applied to. Don't ask me more, because I will just get it all wrong. It is better to go to the Decware site, look in the master catalog, and read the description there.
In short, I was a little scared that I had made a big mistake when I first heard the driver. After 15 minutes of listening, I applied the 'Gizmo' from Decware. This helped the midrange as designed, but there was no bass and the distortion remained. Without too much of my opinion here, I simply will say that bad sound is leaving like a disease, and I plan to find a better amp to drive the speaker. Also, the speaker sounds poorly in my shop for obvious reasons concerning bass. Now the bass has come in, but has some peaks that tell me that it is time to tune the cabinet with polyfill. More later. Greg
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Just for the record, I am using a Deflex panel on the rear of the speaker. With such large magnets, I figured it wouldn't hurt. I used "Emergency Plumbers Tape" to hold it on.
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The deflex pad is supposed to go on the back wall of the enclosure, not the magnet. I don't think Audio Nirvana uses vented pole pieces, but if they do, I would recommend removing the obstruction on the back of the driver before applying signal.
-PB
(Edit: looks like the neo models will need that space open with certainty)
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Thanks for the heads up, and yes the AN driver does have vented pole piece. I cut a hole out just for that purpose. I may have got this confused with a product that was similar and was intended to mount directly on the magnet. It does make me wonder why the Deflex round panels come in different sizes as according to the magnet size. I ordered these from Michael Percy
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Just now, I double checked the Percy catalog, and this product is specifically designed to be mounted on the back of the magnet. I do remember a long time ago, that I ordered Deflex circular sheets that were in fact deigned for the cabinet wall. They were MUCH larger and were the size of the driver being used. Either way, I believe in these products as being of great value for damping purposes. Apparently, this is a newer Deflex product. One thing I like is that by mounting them directly on the driver, it would seem to help control vibration at it's source.
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The Friday update has arrived. Now, don't get any ideas from this. I am not keeping these for my own. I just want to finish break-in in my listening room, and not the dusty shop where I will be making the second cabinet. Also, brace yourselves for another change to the cabinets.
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Here is a preview of my intentions for the cabinets.
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Ok, this what I got done today. The port inserts are now epoxied in place. A little clean up is in order tomorrow. No, the foam is not in way of the port, it just looks that way in the photo.
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Hi Greg,
I guess like everyone else, it would be neat to hear how they sound. The thing that seems really interesting on this one is the port, that is kind of unusual for a single-driver speaker, no?
Dave
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Since they are still breaking in, I have yet to form a more concrete opinion of their sound. I will say that as they continue to break in, the sound has transformed dramatically. When first installed, they were unlistenable. Then after a very short time, they were. After that was a midrange shout that I just hate. Now that is starting to disappear. Even though there is a rising top end, I benefit because of my not so rising top end hearing. Go figure. In time, I expect them to be a good choice for my customer. The bass is too much for me right now, but it can be managed better with the addition of type and amount of damping. I am even making 'port stuffers' to run the speaker sealed. Wait till you see those! heh heh
It is actually not unusual to see a bass reflex design for this type of speaker. The designer highly recommends it for most of his drivers.
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Interesting. What made you pick the audio nirvanas? Any prior experience with them? I like that they have huge magnets, and it looks like they have the quick disconnects too.
Dave
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Actually, this is my fourth pair that I have owned/sold. For the price, they are pretty hard to beat, and since they are full range drivers, that makes me curious as to how well they might perform. I will say that their lower models are not something that I would be so interested in, but the Alnico magnet drivers are quite good. Even though the magnet structure looks impressive, it is the other design characteristics that I like. David Dicks, who is the owner doesn't fool around with the latest fad in audio, whatever that may be. He is competent designer who has set out his goals and has achieved them. That's enough for me. Maybe the same reason that I like the products here as well. You get a basic kit that covers what it needs to, and if you so choose, upgrading/experimenting is up to you. Of course there are the worthwhile upgrades offered by BH.
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Audio nirvana sounds like the Grado of speakers. Sounds like we both think the same thing with going for a higher quality product than looks or small size. My system sounds good now, but the idea of a SET amp like the stereomour seems really nice, but would require getting new speakers (the current ones are 92db sensitivity). Blumensteins look nice, but I look the bigger speakers better, since they are easier to blend with a sub, and sound better. Which speakers of theirs have you tried?
Dave
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I have tried 4 different models, all except one are 8" drivers. In the 8" models I have used the 8" 'Super' which is around $150 a pair. They sounded surprisingly good, money not being a factor here. I made a set for my boss from parts and pieces that I had around the shop. He is a real cheapskate, so my budget was a total of $200. Had it not been for the free stuff, I wouldn't have made it. A couple of years ago, I damaged my very expensive 8" drivers from Decware (FRX drivers are $600 ea.), and had to have something to replace them with in the meantime. I chose the 8" Alnico model for $500 a pr. and was again, quite impressed with the performance. I used a 'GIZMO' from Decware in conjunction with the drivers to tame the sound until the drivers broke in. They were harsh to my ears. The Gizmo is a transformer device developed just for drivers with a midrange shout. Works really good, but adjusting it takes some time. Recently, I bought a set of co-axial 8" drivers from AN for my garage system which I will start on when this project is done. The cool thing about them is that you can adjust the treble output by interchanging a capacitor, but less than what the manufacturer indicates(you don't want too much overlap or gap). Lastly, are the 12" drivers that I am working with here. As mentioned before, I was more curious than anything to hear such a large sized driver. I am anxious to finish the project, but my back doesn't like these mammoths very much, so it is slowing me down. It's just really hard to give an accurate account of any of these drivers since in each case, since I only heard them for a short time. I will say however that set made for my former boss were just wonderful.
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By the way, how do you make the nice round holes/recesses? With a router?
Dave
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Yes, basically with a router, but these drivers are not round. It makes routing a bit trickier, so first you have to scribe lines, and then make edge guide to cut them straight. The rest is done with a circle guide. Slow and smooth, that's how you go.
BTW, David the designer of these drivers has recommended a different driver for my listening room. It is a 10" Alnico type, and I am interested in trying it.
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Guys, I am pretty good at shipping, but have not ever had to ship something of this size and weight. I will be making crates of some sort. Any idea about do's and don'ts?
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Crates sound good. As long as the speakers aren't able to move inside (put enough packing material to close any voids), and have some kind of protection for the finish on the outside, there shouldn't be any issue. Maybe someone else can answer about the speaker itself, any issues with the voice coil bouncing around or something like that?
Dave
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One thing that crossed my mind was to install handles on the sides of each crate. This encourages workers to keep the product upright.
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I would start with a cardboard box that is a little too big. Cut it down to fit snugly. Then use Styrofoam all around that box to make it wedged into the crate.
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I spent 18 years with an LTL trucking company. Crates are good but add a lot of weight. Double boxing is a great way to go. Just imagine you are sending an egg to China. Same deal.
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Thanks guys for the valuable input. After thinking it over, I am going to sell the drivers outright, and keep the cabinets for a very near to do project. Shipping costs will scare my present customer away. These drivers are unreleased products at the moment, but David Dicks advised to sell them and get his top model with an ALNICO magnet. It will raise the price(by $600), but I am actually thinking of using them and having two sets of speakers. One set for rock, one set for the rest.
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I will put this topic to bed by saying that I have worked with these speakers long enough now to say that a certain recipe must be applied to get the desired results from these drivers. In short, tube amplification is to used, and on top of that, the 'Gizmo' device that connects in series with the driver as well. This device a basically a transformer that is designed to absorb a portion of the frequency spectrum that many find offensive from single driver speakers. That is sometimes called 'shout'. This transformer has an adjustable secondary which is responsible for the amount of absorption applied. Too much however, robs the amp of a little power, and dulls the sound. Too little of course, will not have enough of the desired effect in the first place. All in all, I find these drivers best suited for music that demands bass and impact. You can guess the genre.
Having used a D amp with them added insult to injury, and will be avoided in the future.