Author Topic: "MooseStyle BVR" with Feastrex D5nf driver  (Read 37302 times)

Offline richidoo

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"MooseStyle BVR" with Feastrex D5nf driver
« on: October 17, 2007, 05:47:35 PM »
Frugal-horn.com shows a DIY design "Big Vent Reflex" pseudo horn speaker cabinet. The designer, Scottmoose on diyaudio.com, modified his Suzy Chang BVR design specifically for the new Feastrex driver's performance specifications, using Martin King speaker design software. I built a pair out of pine to retain full "mother-of-tonism" and finished them up today. I installed Feastrex D5nf drivers, and connected to Altmann Attraction DAC and BYOB amp with home depot wires. Wow. Spider web - good luck getting away from this... It is intensely emotional, microscope detail, with rich, realistic harmonics. Dynamics, frequency range, musicality are amazing. A lot of this is the Altmann stuff, but the speaker is doing it's part, no doubt.



I wanted to name it "MooseFeast 5" but that didn't take.

It needs some tweeking, the cabinet is resonant and the image is low (these boxes are small) but the sound is amazing. It is definitely full range, with no apologies. I can feel tight clean bass physically. It goes low enough to play symphonies with authority and funky Boney James dance music with full mojo, although not the kick in the stomach feeling of the Legacys. Mids are clear and clean, highs are very extended, no tweeter is necessary. No highs are missed. My beloved bells and chimes sound sweet and rich. When I switched back to the main system, I missed the Feastrex right away, but the Legacys are clearer, more hifi (lower distortion maybe?) greater extension yada-yada... 

I am very excited about this system. Lots of tweaking to come. I will post FR as soon as I can do it. Anyone is welcome to come over to hear it anytime. I will try to pull together a G2G soon now that RMAF is over.
Rich

Offline Carlman

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #1 on: October 18, 2007, 06:37:48 AM »
Sounds like the perfect speaker for a slightly smaller room... with the Altmann system attached... hmmm... Just a thought.
I really enjoy listening to music.

Offline richidoo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #2 on: October 18, 2007, 07:23:28 AM »
Good idea! It might live upstairs in a smaller room, or come apart for an OB project next... :)  It needs 200 hours breakin, amp needs 50, so I will let it cook before any major changes. I look at it as something to tweak and play with, make changes and learn. I like the purist audio aspect of it, soothes my nervosa in a big way by eliminating major areas of anxiety - crossovers, multiple drivers, AC power supplies, cables, etc. I'm relieved it doesn't totally suck. I can actually sit in front of it and enjoy for extended period. Amazing for a first time DIY speaker -hehe   I was expecting much worse.

Offline rollo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #3 on: October 18, 2007, 08:20:50 AM »
Richadoo,
                   Looking good man. Keep us posted.

rollo
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miklorsmith

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #4 on: October 18, 2007, 08:23:54 AM »
Those look beautiful, Rich.  What a motivated learner you are!  What you have going there is diametrically opposed to your other setup but you're openminded enough to dive into the deep (other) end.  Kudos, man.

When I decided to try the single driver thing out I bought a cheap pair of Fostexes and built a pair of bass reflex boxes out of MDF.  They sent me off on a crazy tangent from which I haven't recovered but they're trolls compared to your catwalk hotties.  I'd sure like to hear 'em.

Wanna feel good about your work?

http://www.audiocircle.com/gallery/thumbnails.php?album=687

What's the sensitivity of those buggers?  I'm upgrading my Def. Pros to 2s and I have to sell the Yamamoto A-08s to fund it  :duh but I'd sure like to get that amp in a room with those speakers.  I didn't know you were getting the Altmann amp with the DAC but I bet they're a match made in single driver heaven.  Still, SET tubes . . .

I recently got a pair of first generation Omega hemptone 8"ers to swap in for the Fostexes.  I like them better but now the bass ports are funky, as in I have to replace them.  I think the tuning is too high and it's muddying things considerably.  I have them sitting in my car-vacant garage, neatly spaced for "soundstaging".  It's quite a vision actually, those ugly buggers sitting in a cluttered garage with wooden, folding chairs for "listening seats".  I'm running it all off a discman and gainclone amp and y'know, close your eyes and it ain't half bad.

Anyway, thanks for sharing Rich.  I really look forward to hearing your accounts.

Mike

Offline rollo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #5 on: October 18, 2007, 08:37:08 AM »
Richadoo,
                  Can Altman make the Amp mono? One in each enclousure,maybe? Some cross bracing of cabinet, Black hole pad, spikes and,and. Sorry Nervosa setting in. Oh my!


rollo
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Offline richidoo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #6 on: October 18, 2007, 11:16:05 AM »
Mike, thanks for the encouragement. I really appreciate it. I dug your pics, especially the subtitles hahaha Those look great. I haven't done much with SET yet on the power amp end, but I loved the Art Audio 845 amps in the Daedelus room. That was pure sex, as were the huge 200w radio transmitter tube SETs. If you don't need to be in that same room with Yammys and Feastrex, send em on! hahaha I guess I could send my speakers over too, and with less risk...

So much hype about this alternative hifi stuff, I just had to bite to see if any of it is true. It is true, but is still very different than our American muscle and refinement through technology approach which of course is superior in everyway except transmitting the glory of God, which is why I listen to music anyway. That's what makes the japs go nuts over this wacky DHT amp and paper driver shit. It is pretty cool, but it exacts its cost in several ways, in money and in departure from perfect distortion specs which American model is based on. I say American as opposed to European which also follows the distortion spec model only because Americans are less willing to sacrifice the lowest octave which requires 4x power and 4x bigger speakers to maintain same low distortion as upper octaves.

BTW, the Zu Defs were used as reinforcement for singer at the show. They sounded really great. Much better than the demo room they were in last year with local dealer.

The Altmann amp is pretty cool. Mine is used and the seller voided warrantee by removing from the wood board (actually cut in half trying to put inside a box  :roll: )  But the discount was worth it and now I am free to have a close look at what's going on. The amp's PCB is not setup for running as monoblock, but maybe L/R input signals could be rigged for mono input yielding a monoblock, or at least a biamper. I would have to really think about it and get some help to try that. Expensive if I screw up. Power is an issue for me using it with the Legacys. The amp sounded incredible on first day, so I think it is worthy, then developed a distortion while playing some brass quartet stuff which is demanding on current - long mid and low freq sinewaves at medium volume, but the Focus is 2ohms at 75Hz, right in Tuba land. Heatsinking was not good as received. It looked like stock, but I think that maybe the seller did not reassemble the heatsink correctly, which allowed overheating. I improved the heatsinking, but not sure if the chip is already damaged. It is supposed to have a lot of protection modes for heat and shorting. But I can hear a little bit of ick in there after it warms up, even with the 16 ohm Feastrexes which offer tiny load, they are 97dB@16ohms. I will ask Charles what's up, maybe he can solder on a new chip and check it over. But yeah, the sound is really something very special. I would love to have 4 of the them running as monoblocks hanging like ornaments off the high and low speaker posts behind my speakers, with a battery on each side. Add it to the list of to-do's haha. It would cost $4000 list to buy them new. But actually it would probably be worth it compared to similar performance from AC powered 4k retail amps. To get this kind of bass you would need 200w+ ss per side. Unbelievable bass. Once I make sure it is healthy I will send it on a tour.

Snappers sound great on the new speakers too. Lots of power reserve, and ease playing big music.

Rollo, you are absolutely right about the tweaks, and they are coming, even the black hole, bracing, and another trick used in Feastrex' own speaker boxes, mounting the driver from behind on a crossbrace in side the cabinet and isolating driver from front baffle altogether. Still raw wood too, might put a coat of something natural on there which will tone down the mid hype I think. Altmann suggests homemade turp and resin, but that will stink for a long time.
Rich

Offline Carlman

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #7 on: October 18, 2007, 11:36:25 AM »
Rich,
For the finish, consider antique oil or an oil rub... Linseed or something like that... It's natural, penetrates, leaves a nice luster, and is easy to maintain... It dries fast, doesn't smell, etc.  I've refinished pine with it before with excellent results.

-C
I really enjoy listening to music.

Offline rollo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #8 on: October 19, 2007, 05:56:55 AM »
Richadoo,
                  What about simple Varnish as a finish? So whats a little smell. It goes away.


rollo
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Offline richidoo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #9 on: October 19, 2007, 11:53:02 AM »
Thanks for the finishing advice. When I'm not audio-insane I use General Finishes products which are awesome. But they have poly in them, and musical instruments should have a natural resin based finish. Altmann and his "mother of tone" stuff suggests dissolving colophony (tree resin) in terpentine. This has reputation of drying VERY slowly if at all. Actually I am thinking now that it is a little over the top anyway, so I may just stop worrying about it. haha  The smell of terp doesn't bother me, but mineral spirits does, especially if it dries slowly and lasts for months. I'll have to experiment a little.

I wrote to Altmann about the distortion, he replied quickly with advice I should have thought of. Charge the battery dummy... (my words, not his...) I was using a new battery, and knowing it was pre-charged I didn't bother to get a charger yet. But without load the battery is at 12.5V. With a 5A load, voltage will drop farther and make the chips distortion go way up. At 9volts it is a total wimp. Chip can source 9A and I bet the Legacys are drawing that on peaks. So now it's on charge, and I'm looking forward to that great sound coming back. Sorry for the false alarm, I overreact when I think things are prematurely broken.

The drivers are loosening  up a lot, sounding better. My wife and oldest son think they sound the same as the big speakers. For once I thought that was positive news. :) Wife heard the Altmann's clarity immediately on first night, when battery was still charged.

jrebman

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #10 on: October 20, 2007, 06:21:52 AM »
Rich,

Sounds very, very cool!  Just don't overdamp or overbrace the cabinet, and you might find that some cotton or wool felt padding may work better (and cost a lot less than BH5.)  And when you're ready to try another type of cabinet, the Mileva monolith-type (sideways turned QW pipe) should be able to be tweaked to work with the D5.  It's the smaller brother of the "Demetri" that I heard in Michael Mardis' room.  It is also designed for the driver to be in contact with one of the braces.

Keep us posted -- this sounds really fun and interesting.

-- Jim

Offline richidoo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #11 on: October 20, 2007, 08:02:30 AM »
Thanks Jim, that sounds interesting. Another cabinet design created especially for the driver came across my email yesterday. It is a small box and has a simple TL inside the box. I thought TLs had to have an exhaust vent to ambient pressure, but this one seems to be a sealed speaker with dead end TL. Picture here. Is that possible? It is a quicky napkin sketch with no details,  so maybe it is just understood that it should be vented, but not understood by me! It is supposed to make the driver sound like OB, using Martin King TL parameters. Actually after looking up your Mileva design, Jim, I see a bunch of dead end TLs called ML-Voigt. What does ML mean? The Mileva design looks cool. I wonder how to modify it for a different driver. I need to buy and learn to use Martin King's spreadsheets.

After more listening yesterday, I am starting to hear the wood's resonant contribution, and the slight shoutiness of the horn mouth. So some damping is required. I intend to rear mount the driver on a beam across the inside of cabinet which will stop some of the box ringing, then tape some newspaper balls into the corners, etc. At least for a start. Maybe some towel layers for reflection damping. There is a sealed empty volume under the slanted board that makes the horn. I am thinking of filling that up with spray foam urethane which expands and should lock the walls tight. Any opinions on that method, besides don't use too much? I know it can rip the box apart as it expands. I also thought of filling it with concrete, but I like the portability of these speakers,  something I don't have with the 185 pound Legacys.
Thanks
Rich
« Last Edit: October 20, 2007, 08:20:45 AM by richidoo »

jrebman

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #12 on: October 20, 2007, 08:30:41 AM »
Rich,

ML = Mass Loaded.

As for dead-end pipes, haven't a clue -- never heard of it, but that doesn't mean much.

One thing I used to do in the speakers I built back in the 80s was to use a piece of cotton rope -- maybe 3/4" - 1" glued along the seams.  The same kind of stuff you might find used as mainsheets on a sailboat (wonder where I got the idea :-) ).  As for lightweight filler,, again, I have no particular recommendation as I've never used anything like that, but my guess is that the various things like sand, shot, BBs, etc. while filling the empty space and stiffening up the surfaces it is in contact with, also help to add solidity to the speaker as a unit, and damp the box movement, and anchor it to the floor better.  Still lots of experimenting to do here, but I feel pretty hampered without access to drawings, etc.

Another finishing option that I have used and love, and which as been around forever are the poly/oil finishes from General Finishes -- a small company somewhere in Minnesota.  They are wipe-on, come in a few finish textures from satin to high gloss, and also include a pre-sealer that really brings out the grain in the wood.  I used to use a single coat (no more) of their Seal-A-Cell, followed by as many coats as you wish of the Arm-R-Coat.  People have reported these finishes to look as good at 40 years as the day they put them on.  It is also a really great finish to use for the bases and wood panels on tube amps because it is very heat resistant.

Between your experiments, what I saw at RMAF, and the ideas I've been kicking around for a while now, I've finally reached the point where I just need to grab the bull by the horns and figure this thing out -- how I can read drawings, graphs, etc.  I have a high-resolution tactile graphics printer (4x the resolution of standard braille), and software that in theory will let me print this kind of stuff, that I've been playing a role in the development of for the past 10 years, and now it is time to see if it can do more than simple charts, etc.  If I can get this working reasonably well for PDFs of drawings, FR plots, and schematics, then I'll be a happy camper.  I've got room cleared on my desk now, so today is the big day to try a few test prints and see what happens.  Keep your fingers crossed.

-- Jim

Offline richidoo

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #13 on: October 20, 2007, 11:56:30 AM »
That would be awesome Jim, good luck. I'll help however I can.

Bryan Pape sells cotton insulation which is great for acoustic absorbtion. Mashed into interior corners I think it would along same line as rope, but maybe a little more porous. Great idea.


miklorsmith

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Re: "MooseStyle BVR" with Feastrex D5nf driver
« Reply #14 on: October 20, 2007, 12:33:05 PM »
Good luck with that, Jim.  You are a resourceful dude.

In my BR boxes, I used thin carpet underneath and pillow batting on top to line the driver chamber.  It has sensible visual effect but I have no clue what the acoustic benefits are.  It WAS cheap.