The Vifa can still work even with two 12 inch drivers as Sd of two 12's is like one 15 inch which is really the minimum to get enough displacement for nice bass in an OB. The efficiency of two 88dB drivers in parallel is 94dB at same voltage and you have the baffle step loss and also the -6db per oct falloff from the OB frequency of circa 300 to 400 Hz. It doesn't hurt to have a higher efficiency full range like the Faital Pro - not sure you need it yet. If you went with qnty 2 Alpha 15a's at 97dB ea, it would definitely make more sense. I think the 4FE35 is the one you want - higher Qts and more xmax.
If you want to try a different amp, I can highly recommend the Texas Instruments TPA3116D2. Very nice sounding and now comes pre built for $15 to $30 as a board or $60 in a case with banana plugs volume control etc. Look in the class D forum it is the hot thread right now. I built mine from scratch before they were available ready made. Now they are basically giving them away. The latest variant is referred to as the "YJ 2.0 Blue Board" - it was a design made by member Danzz that was lifted from the forum and made by the Chinese at a price less than the BOM if you were to do it yourself. 50 watts per channel in stereo. A monoblock version capable of driving 2 ohm loads at 100 watts is also available. Anyhow, they sound fantastic and if you don't like it you are only out $15 to $30.
Here's a cheat sheet of all the variants:
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Nice shout out on the class-d amps, the YJ Blue Board 2.0 is currently on offer at $20... will get a pair of these.
Think I'll save a few £'s and stick with the Vifa unit and try out 2 x 12" per side. Will wait a couple weeks before I start this, it'll give me time to finish off my current projects and save-up a few more pennies
Big thanks for all the help and great info
Think I'll save a few £'s and stick with the Vifa unit and try out 2 x 12" per side. Will wait a couple weeks before I start this, it'll give me time to finish off my current projects and save-up a few more pennies
Big thanks for all the help and great info
Jonnoshore,
I can't compare to the Naim as I have not had a chance to listen to a Naim or use one. Based on the specs of the Naim, I have to imagine it would be better given that it can handle 400VA peaks with 80 watt RMS rating. It is a class A/B amp probably and I think the TPA3116D2 sounds better than most class A/B amps out there (class A/ amps have a zero-crossing distortion that is inherent in class A/B topology - and I think this is something I can hear). The clarity and detail is unbeatable, and this gives the soundstage an amazing presence. The bass is also very rich and powerful and you can really hear the difference on a speaker like the Nautaloss which reveals the dynamics clearly. The distortion rating of the TPA3116 is very good at 0.1% THD at 40 watts rms into 4 ohms. For full range drivers, that is all you will need. I have compared this to the two other class A/B amps I have and I think it sounds better - and if you look at the price or value, nothing can touch it. I have a couple of the green Ybdz's on order (still not arrived yet) after I placed my order the blue YJ came out. I will probably get one but want to wait for my current order to come in first. At $20 ea you can't go wrong - ordering through Aliexpress can take some time though so be prepared for a 3 week wait. I have heard ordering direct from YJ is faster but you have to pay shipping.
I can't compare to the Naim as I have not had a chance to listen to a Naim or use one. Based on the specs of the Naim, I have to imagine it would be better given that it can handle 400VA peaks with 80 watt RMS rating. It is a class A/B amp probably and I think the TPA3116D2 sounds better than most class A/B amps out there (class A/ amps have a zero-crossing distortion that is inherent in class A/B topology - and I think this is something I can hear). The clarity and detail is unbeatable, and this gives the soundstage an amazing presence. The bass is also very rich and powerful and you can really hear the difference on a speaker like the Nautaloss which reveals the dynamics clearly. The distortion rating of the TPA3116 is very good at 0.1% THD at 40 watts rms into 4 ohms. For full range drivers, that is all you will need. I have compared this to the two other class A/B amps I have and I think it sounds better - and if you look at the price or value, nothing can touch it. I have a couple of the green Ybdz's on order (still not arrived yet) after I placed my order the blue YJ came out. I will probably get one but want to wait for my current order to come in first. At $20 ea you can't go wrong - ordering through Aliexpress can take some time though so be prepared for a 3 week wait. I have heard ordering direct from YJ is faster but you have to pay shipping.
Ordered two YJ Blue Board 2.0 amps and a pair of Vifa TC9FD's... a pair of Alpha 15A's is a good idea, per pair price is slightly less than 4 x SpeaKa 12" I was looking at. An 8' x 4' sheet of 18mm MDF is £20 locally and can get it quarter cut for free [4Qty 1220mm x 605mm]... that should be enough for a baffle and extra bits.
Downloaded a copy of EDGE also.
Downloaded a copy of EDGE also.
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Paul,
Now armed with the miniSHARC, DAC's, drivers, and baffle plates you look like you are set for some good old OB fun!
Let us know how those blue amps work out for bi-Amping. You may want separate power supplies for those amps as Dug in class D forum mentioned that there may be switching speed modulation beat freq if same power supply is used? The amps actually have master/slave settings for oscillator. I don't know if it is a real issue - try both ways.
Good luck!
Now armed with the miniSHARC, DAC's, drivers, and baffle plates you look like you are set for some good old OB fun!
Let us know how those blue amps work out for bi-Amping. You may want separate power supplies for those amps as Dug in class D forum mentioned that there may be switching speed modulation beat freq if same power supply is used? The amps actually have master/slave settings for oscillator. I don't know if it is a real issue - try both ways.
Good luck!
Using separate power supplies seams the logical thing to do with the amps. Not 100% what the Master/Slave settings is used for... will have a good read of the datasheet.
Came across Martin J Kings site wile looking at TL designs last year, a revisit showed an OB design using the Alpha 15A and Fostex FE103E driver... the Vifa should work, just a little quieter.
Most of the bits already ordered should arrive over the next week or two. Material for the baffle only requires a trip to the local DIY supply store, and the Alpha's would be next day delivery once ordered... What ever baffle size I go with [20" x 38" probably], I want to paint them either high gloss yellow or red
Came across Martin J Kings site wile looking at TL designs last year, a revisit showed an OB design using the Alpha 15A and Fostex FE103E driver... the Vifa should work, just a little quieter.
Most of the bits already ordered should arrive over the next week or two. Material for the baffle only requires a trip to the local DIY supply store, and the Alpha's would be next day delivery once ordered... What ever baffle size I go with [20" x 38" probably], I want to paint them either high gloss yellow or red
A short note regarding the interesting SpeaKa 180/200 unit. Conrad electronics advertise it as having a Qts of 1.39. I immediately ordered 2 pieces, but when they arrived the printed specs quote a Qts of 0.54, which makes them much less interesting, to say the least. So, before ordering make sure that they can actually deliver. (Fortunately their return policy seems ok - but it is a bother nevertheless.)
You might be interested in this lazy man's OB using a single sheet of FC. http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures-225.html#post3840132
As a ceiling mount it would not have the dipole open baffle effect - which really makes a huge difference in the quality of the sound. I was really surprised how good they sounded considering how simple it was. From the impedance plots it is obvious that they are acting like multimode cones - maybe like the balanced mode radiators out there? How much of this sounds like a planar electrostatic or electromagnet speaker I wonder?
I have been lurking these forums since 2009, posting a quick answer once or twice. But when I saw this I had to step into the fold. This is indeed an excellent design. I completed one that was very similar last spring. It was CNC cut from MDF and uses constrained layer damping in the main baffle with very specific cutouts. Uses the same Vifa mid/tweet, except it's a 1-1/2 config (inductor in series with the top mid). Woofers are 8x Aura/NS6-255-8A. Directivity is very uniform from as low as I can measure to above 14K except for a shoulder around 1K. See pictures. Crossovers, Eq and amps are provided by the Hypex modules you see in the photos.
Not quite so cheap and fast, but it is simply the most natural bass I have ever heard. The mids sounded so good full range that I never finished the x-over for the dome/waveguide that is shown in the photos.
I was thinking of posting the construction details in a thread, do you think this will be of interest?
Attachments
Most definitely - YES!!!
Z,
It is so cool to see that our designs are so similar (it's almost creepy). I want to build mine out of wood when I get a shop - they sound great and the bass is superb. The cardboard sounds really good, I can only imagine how much better in wood. As much as I like foam core and cardboard, this speaker needs wood and you are probably even better off with constrained layers. It makes some serious pressure with 6 in my case and 8 drivers in your case. I see you stacked yours in push-pull asymmetrically opposed arrangement too. Please explain what is going on on the top - it looks like the Vifa has a cutout around it to provide better imagine? The Vifa directivity is indeed very good. I have some measurements in another thread if you are interested:http://www.diyaudio.com/forums/attachments/full-range/402191d1393333563-3-4-driver-very-good-dispersion-high-xmax-nautaloss-ii-2-drivers-polar-1m.png
Cheers,
X
I kick myself for not buying those 6 in Aurasounds when they were on sale!
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