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I see them on ebay/craigslist from time to time. but fat chance on getting one here in s fla. so i've been looking at a7 plans and i know i could do it. (it might be easier than finishing my boat. ;) maybe cheaper) if i can get a set of horns. it's on. battleship grey, no veneer, no bling, no foo foo. just brute force
I wish you well. :)
Eh hem...GO FOR IT...and post lots of pics :)
My advice is to build them all at the same time. If you're going to build a pair or a dozen, keep them both/all at the same stage of completion at all times.
Buy extra stock for the curved horn flares, unless you excel at advanced trigonometry and can easily calculate the arc'd cut for the bottom of the flares where it meets the sloped horn bottom panel, you will cut a few before you get an acceptable fit. I used fir, it's much stronger/denser than the typical pine ply factory cabs were built from, i kerf'ed it on 1/2 inch centers to get smooth bends.
One piece full back panels to give good access for further tweaks. I braced mine internally, i think the exterior braces are unsightly, and they can stand to lose some internal volume.
Add a 3rd or even 3rd and 4th curved brace behind the flares.
Make the motorboard/woofer mounting baffle the full width of the cabinet to seal off the horn flare cavities and add strength.
Add copious amounts of HARDWOOD bracing internally to stiffen large panels.
You can play with the port size and tuning until the cows come home. However, the reflex portion of the system will never make extended bass that can track the rest of the system in scale or dynamics. Corner loading or specific placement along with a tad of careful EQ can get them acceptable in larger/harder rooms. Proper subs shine a whole new light on them.
Note the 1/4 ply added to the woofer mounting baffle is not necessary with an Altec woofer. I'm using a non-Altec woofer where the lack of gasket thickness would allow the forward edge of the cone to contact the baffle at the throat constraint on long excursions, hence the spacer.
http://www.hostboard.com/forums/
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http://i107.photobucket.com/albums/m...7ss/A7s816.jpg
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For subs, i've built many of these. Some are still cruising around here in the northeast doing live sound 2 or 3 nights a week. The box is simple with internal volume and porting very similar to JBL 4719. Internal bracing is extensive.
Originally loaded with 2241's, decided to try the MCM brand 18 inch woofer when they came on sale for 97 bucks each. Found them to be so close to the 2241 in this box that saving 200 bucks per driver was a no-brainer, and i'd consider using them again.
http://i107.photobucket.com/albums/m...auseheslow.jpg
You'd be surprised what you can find. I found a pair of empty cabs in NY http://www.hostboard.com/forums/f700...ets-ny-ny.html just after I decided, like you, to build them. For $162 I couldn't have purchased the materials.Quote:
Originally Posted by Phil-G
Correction: Audio_by_goodwill found them!! Stick around here. These guys are great at scouring the universe for Altec gear.
bowtie are these the mcm woofer you mentioned?
MCM Audio Select 18'' Die Cast Professional Woofer - 700W RMS | 55-2984 (552984) | MCM Audio Select
Actually they don't make them anymore.Quote:
Originally Posted by Phil-G
This is the woofer, same catalog number but now it has a smaller magnet and lower power handling. here also is a crappy photo of the catalog page of the ones i actually used, note the 100 0z magnet and 400/800 power handling:
MCM Audio Select 18'' Die Cast Professional Woofer | 55-1875 (551875) | MCM Audio Select
http://i107.photobucket.com/albums/m...ps047ef76c.jpg
i've ordered some stuff from mcm. but i usually just order small stuff, like semiconducters from mouser. so anyway i'm getting a little in the weeds with the altec 15/16s can you clue me in to a set that would work with (the set of horns i might have, if the guy sends them.) 902 811s? and how does the horn in the port thing work out? seems like it would save space.
If you don't need high power handling, 416-8B would be the woofer of choice whether vintage Altec or new GPA production. They would also play well in a conventional bass reflex box, and they play well high enough to use a 1200 hz XO.
On a budget, it's still hard to beat the Altec 3156 OG mentioned. They're almost always available on ebay down around the hundred dollar mark, an Altec woofer for little more than a C note! New ones from GPA are 250 on ebay, and they have that wonderful new smell that will last several weeks. I wish i could afford some new cones myself, craving that smell, LOL!
i'm not above spending the money on the gpa's. but i do love the vintage sound. so the 3156s might have to do. i know the 416s are rated for lower wattage but realisticaly how much sound do they put out?
Enough to make you deaf in a very short time.
"how much" is precluded by "how good". In terms of sound quality, there's probably no better choice in an A7 than a 416-8B. It doesn't have the motor strength of the 515, the 515B rivals everything in terms of midrange and dynamic punch. But it won't play as low in a small VOT, and the 416-8B's mids come mighty close.Quote:
i know the 416s are rated for lower wattage but realisticaly how much sound do they put out?
The 416-8B's will play loud enough to drive everyone out of your house and get calls into the local PD from 3 out of 4 neighbors. You can actually drive them quite hard, but i recommend a high pass filter and the awareness that they will break and were not designed with long term heat dissipation in mind. I don't personally know anybody that's broken a 416-8B in a home environment. But, i have bought several broken ones not knowing the story of their previous fate. So, somebody out there breaks them, or used to.
The other thing to consider is resale/return value. With genuine Altec components(and most GPA products), if you buy them carefully you haven't "spent" any money, you just "parked" the money in some Altecs for a while.
I can tell you that I have old (1960's) 16-ohm 416As in 816 horn cabinets in the garage. With the new passive XOs (900 Hz) I have on them now, they sound amazing. Great mid-bass sound with a solid bottom end. With a pretty wide range of source material, they perform very well. They make MP3s sound like the crap that they are, and well-engineered recordings via WAV files sound marvelous. I am running them through an old Onkyo SS amp, and can't apply more than a few watts or they're running me out of there.
Yup that's why i scraped MP3's long ago... I use only .flac files now played on Foobar2000 media player. There really is no comparison ! :wink2:Quote:
Originally Posted by Alien_Shore
http://flac.sourceforge.net/
i have a flac version of pinkfloyd animals. it will fit on a dvd. sheep is over 250mb.
on a side note im getting a bit concerned about my horns. i haven't seen a tracking # yet. it's been 2 days.
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ok what's the skinny on this pair?
http://www.ebay.com/itm/2-ALTEC-Lans...item4171556a14
they look like they come from the same vintage as the horns i may or not end up with.
If you are not in a hurry I'd keep checking craigslist. I finished a task at work on Friday, didn't feel like starting the next project quite yet, checked some keywords on cl and there its was; posted that morning, 3 A7 cabinets about 1.5 hours away. They followed me home this morning. Total $ less than the wood to build 1.
They are all identical, appear to be factory built, such as it is/was. They were not built all that well. If you have any skills I suspect yours will be built and sealed much better than the originals. Also, mine have random nicks, scrapes, gouges, screw holes, etc. from past adventures.
I guess it boils down to your skills. I have very few with wood and decided that purchasing and fixing is easier than building. If you are good with wood these seem fairly straightforward with lots of room for improvement in bracing, materials, and construction.
Greg
I agree with all bowtie, alan and Greg here but want to add or reinforce some points.
If you can find them for sale they will be cheaper than building them (usually)
They need internal bracing. The external bracing on mine are more like skids so when you lay them on their backs, you are sacrificing only the skids. I never thought of them as panel braces.
Yes carry the mounting board to the full cabinet width.
If you plan to use a separate woofer, consider going with one of the 421's in the A7 cabinet.
The vent size should be reduced depending on the size of your room. I would make it 75 square inches for an average sized livingroom.
Use a minimum of the 511 horn or go wild with multicells.
Quote:
Originally Posted by bowtie427ss
To get the same specs, 800 Watt,100Oz magnets you have to move up to the 21" woofer.
MCM Audio Select 21'' Die Cast Professional Woofer - 800W RMS | 55-2985 (552985) | MCM Audio Select
Edit; oops, same as the one posted above. LOL
This one looks promising in a 16 cu ft box;
MCM Audio Select 18'' Die Cast Professional Woofer - 700W RMS | 55-2984 (552984) | MCM Audio Select
Input it into WinISD and it looked pretty good, but I am sure I don't know how to use it.
A pair in south Jersey
Altec A7 Speaker Cabinets
you gonna be in s fla anytime soon? :DQuote:
Originally Posted by alancohen
Ooops, I thought you were in VA for some reason...never mind.Quote:
Originally Posted by Phil-G
Actually, I just got back a week ago from FLA. My parents live in Coconut Creek. Somehow I don't think I could have gotten them past the TSA, however.
tomorrow is the day i'm getting the plywood and starting. i have the layout for all the cutouts. i should have very little waste.
i have read panos thread twice and anything else i can find on the subject. what i've learned is;
1 brace the inside on any panel over one foot using the .7 ratio GM suggests.
2 deaden the horn. i'm thinking about making a composite horn flange using a hull system we use that's eaten small arms fire
3 adjust the port for better LF. possibly turning it into a horn in itself.
4 i haven't finished reading some of the old posts yet.
but tomorrow i'm starting.
I had some plans I drew up for an a7 it was made from solid plywood It would have weighed a ton and cost a fortune but I bet it wouldn't have resonated. It too had a horn for the port. everything was rounded no sharp corners.
i got almost all of my box pieces cut. all thats left are the bevels on the horn bottom plate, and the front piece that butts up against it.
i'm still leaning heavily on forming the horn flanges out of fiberglass composite. 1208 glass with divinicell coring. using vinylester resin. one things for sure. it would not give.
cradeldorf id be interested in seeing what you had in mind for the port horn. otherwise i'd like to do what GM suggested to pano and do something like an 8" tube.
maybe a little overboard but i thought it made a nice pick. :D
If it can be done with without looking different/odd, I'd go for it!Quote:
Originally Posted by Phil-G
I'm sure it would sound fine, but too me, the look wouldn't be right. Did GM say why he suggested it? Does it have an advantage?Quote:
.......otherwise i'd like to do what GM suggested to pano and do something like an 8" tube.
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I'd love to build a cabinet someday.........someday when I get everything else done that needs to be done!
you would never be able to tell once it's painted. it would be simply like a section of high performance boat hull. it would look exactly like what comes with an A7. i do a lot of custom fiberglass at work plus electroncs and mechanical systems.Quote:
Originally Posted by Audio_by_Goodwill
phil..you started today?! you are inspired...i'm impressed. lookin' good
he did but i wouldn't have understood half of what he said to save my life. sufficed to say it would work. i don't care what it looks like as long as it works.Quote:
Originally Posted by Audio_by_Goodwill
i have a lot of things that need to be done. but i just want to hear what these sound like.Quote:
Originally Posted by Audio_by_Goodwill
Okay I'll flicker them tomorrow and post them on this thread. :)
Here it is, The bottom part of the main horn was actually gonna be a bunch of laminated 3/4 plywood pieces that would also form the upper mouth of the bottom rear wave horn. The sides of the upper horn would also be constructed this way as to eliminate hollow area's that might resonate. Also there was gonna be a laminated half arc piece behind and above the speaker to eliminate some of the square corners inside the cabinet. The entire path the rear wave was to follow would be very fluent.
BTW this is not the standard A7 cabinet size, I think it's smaller. Also the bottom horn is not calculated at all. It' was just a thought and a drawing.
SpeakerCabinetSmall | Flickr - Photo Sharing!
thats a great drawing
i was thinking of a horn similar to what your drawing shows. but i need to draw what i'm thinking.
Don?t recall what I posted, but a few things come to mind WRT round Vs other shape vents:Quote:
Originally Posted by Audio_by_Goodwill
1] Round is the most efficient, so is the shortest for a given tuning.
2] Round is easiest to make, fine tune.
3] Because of [2], no need for gasketed plates that can leak, altering tuning.
As far as cosmetics go, that?s what grill cloth or similar is for ;) plus I?ve found that most vented alignments benefit from minimal internal damping combined with ?critically damping? the vent, so the grill cloth can do double duty as part/all of the damping.
GM
thanks GM. how would the smaller port work in a larger venue? like a 90 x120' or would it only work in a smaller room like a living room size 15x30'
You're welcome! It would depend on the room's acoustics, speaker location and how far away the listening position is no matter what the room size, but as a general rule a high tuning would be used for prosound/really big rooms apps and add a separate sub system if usable output below ~60 Hz is desired.
GM
GM, if we're talking about an A7, they typically have a port only as thick as the wood used, and often don't have grills.Quote:
Originally Posted by GM
You mentioned efficiency, but in what regards?
pretty good chance we're talking a7 or 828 somethings here. :D
although what i end up with will more than likely have an asterix at the end of the title. being a diy project it's not uncommon to vear off the typical. and anything that improves on a 40 year old design is going to be used.
[1], [2] for any vented alignment and all three for reflex [baffle thickness vent].Quote:
Originally Posted by Audio_by_Goodwill
Acoustic efficiency, i.e. round has the least frictional area WRT cross sectional area [CSA] , ergo for a given tuning it will have the shortest vent.
I don't see where having grills or not is relevant per se, i.e. it's a design choice which in the case of the VOTTs is probably ?bean counter? related and from a purely technical POV, critically damping the vent is normally required for best practical sound quality [SQ] and always with a reflex vent in a HIFI/HT app.
In your case it can be shaped to imply an A7?s full width slot or even the later 828H ?window screen? variant, which to is the best looking short of the whole cab being ?grilled? with a horizontal accent below the horn.
GM
had the cabinets laid out,, and i know i said i didn't care about looks but, after looking at the plywood i decided to finish them with a nice blond woodgrain finish. so instead of bondo, battleship gray, and chainlink grills NINs style. i spent the last couple days truing up the edges for a cleaner look. so tomorrow i fit everything and bond them together. hopefully monday i start on the horn flanges. i want almost more than anything to hear these beasts roar in less than three weeks.