Found these M14s in a lot
Bose Altec AR Speakers | FleaBay
The seller tells me they're all original. Look good, and within striking distance.
Anyone see anything that causes a concern?
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Found these M14s in a lot
Bose Altec AR Speakers | FleaBay
The seller tells me they're all original. Look good, and within striking distance.
Anyone see anything that causes a concern?
OK, these look really cherry:
Attachment 1324
I talked to the seller today. He has had them for about 3 months after getting them at an estate sale. I think I'm heading up this weekend. If they're all original, it seems like a good deal.
From what I can see in the photo, they look to be mint or near mint (other than possibly needing new grill cloth). If they are mint/near mint and all original as the seller claims, $400 is a great price. I paid $430 for my mint pair -- and had to "talk the seller down" to get them for that price. Also had to drive 6 hours round trip to buy them from the Watertown, NY area (3 hours each way). You won't be disappointed by Model 14's--they give the 19's a run for their money at all but the very loudest volume levels IMHO (louder levels than I'd ever want to listen at). Good luck--let us know how you make out with them -- more photos would always be nice as well....
540 miles round trip...it was a pleasant ride though - rode through DC and saw some really nice scenery.
Anyway, the cabinets are a little beat up (tops are pretty rough), but they do sound great.
Here's a couple pics from the front porch audition. First up Michael Buble's first CD, next Steely Dan's greatest hits.
https://live.staticflickr.com/65535/...08954d77_c.jpg
HAPPY MEMORIAL DAY YOU GUYS!
Congrats on the Score !!!
so,
you 'passed' on these two?
http://www.hostboard.com/forums/hbmc...2012/05/51.jpg
http://www.hostboard.com/forums/hbmc...2012/05/52.jpg
Quote:
Originally Posted by Alien_Shore
I've looked a little closer and it looks like the dust cap has been glued differently indicating recones on at least 1 woofer.Not a problem though if done properly.The cabs look like they are in pretty nice shape from the front.
I noticed the glue as well, however removing the dust cap to center the woofer with shims is an important part of the re-foam process. Thirty year old woofers of this type would almost certainly have been in need of a re-foam, so new glue around the dust cap(s) tells me the re-foam was probably done properly (with shims). The cones look like they may be original to me, although it's hard to tell from the pics. There should be cone numbers on the back of the cones--that would of course tell if they're the original cones or not......Quote:
Originally Posted by Altec Best
The drivers do appear to be all original equipment. The woofers are the usual suspects: cast frame RCA 34633. The compression drivers are the OEM 902 ferrite units.
As VOTT says, the woofers would be expected to be refoamed, and indeed that appears to be true. I think they were done professionally, it looks to be very good work on both woofers. Some pro sound shop in NYC must have done them, as they put their stickers on there. Good news is that original cones and VCs appear to remain in place and look to be in great shape. Can someone with original drivers let me know what the cone number is?
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Both woofers sound good. One VC shows a DCR of 8.0, the other 4.0 :confused:
The HF drivers both show good DCR. As mentioned, they are the OEM 902s with no back cover and the loading caps. On one of them, I heard the tell-tale occasional buzzing sound and upon inspection the phase plug is loose. I suppose I will need to do a little research on how to shim it and glue it down. Maybe remove the loading caps and replace with felt while I'm at it?
I just went through my photos of my Model 14 woofers and none of them showed the cone number :( So I pulled both of them and took a few new photos. It looks like we have different cone numbers. I always assumed mine had the original cones, but you know what they say about when you assume. Anyone else out there know which of these are original cone numbers? Or did Altec change cone numbers during production and both pair have original cones (mine are from 1981 and Mike's are from 1980). Mike, you mentioned one of your woofers has a DCR of 8.0, the other 4.0. That is unexpected. Do they both have the same cone number or does the cone with the different dust cap glue also have a different cone number? (my two woofers have matching cone numbers as seen in pics below) BTW, as Altec Best alluded to, reconed woofers are not a problem IMHO if they were reconed by GPA (or by a pro using GPA kits) since their cones are built to Altec spec......Quote:
Originally Posted by Alien_Shore
http://www.hostboard.com/forums/hbmc...2012/05/53.jpg
http://www.hostboard.com/forums/hbmc...2012/05/54.jpg
http://www.hostboard.com/forums/hbmc...2012/05/55.jpg
http://www.hostboard.com/forums/hbmc...2012/05/56.jpg
http://www.hostboard.com/forums/hbmc...2012/05/57.jpg
Thanks for the pics, VOTT.
I spent a bit of time looking around on the web today, and I think you probably have original cones. I suspect mine are replacements, and probably not GPA. As far as the DCR on the one woofer being low, I agree it is concerning. I may give Bill H a call and see what he wants to just recone them, since the wierd DCR probably indicates a problem with the VC.
I did some further inspection tonight, looking at the HF drivers, and the crossovers. Here are some more pics:
I think this is the 902 8A?
https://live.staticflickr.com/65535/...70c48541c9.jpg
Here you can see the loading cap is cracked. It had a bad bolt on it, which was overtightened :rolleyes:
https://live.staticflickr.com/65535/...13bf1c09bf.jpg
https://live.staticflickr.com/65535/...379b3cea17.jpg
Phase plug on this one is still glued down tight
https://live.staticflickr.com/65535/...072614b0c6.jpg
But VC and phram look fine...looks like the original lightweight ones
https://live.staticflickr.com/65535/...a53f9b747a.jpg
The crossover unit looks like it needs some work. I suspect those caps are not what they used to be after 33 years...
https://live.staticflickr.com/65535/...f91b7b615a.jpg
A fun project to fix these up and get them in like-new listening shape! :D
I agree-mine look like an original Altec cone number (format). Well worth having GPA re-cone yours. They'll be as good as new/up to original Altec spec.Quote:
Originally Posted by Alien_Shore
Those do look like the original diaphragms--same original diaphragms that my 902-8A's came with. They are 34647 diaphragms, not the lightweight ones.Quote:
Originally Posted by Alien_Shore
I would definitely re-cap the crossovers. I did mine with Solen "fast caps" (recommended by GPA) and they dramatically improved the sound quality..... Somewhere on this forum there is a thread about my Model 14 crossover recap--with pics, etc.....Quote:
Originally Posted by Alien_Shore
I'm curious, what is the part number for those "lightweight" frams? All the doc that I can find only mentions 34647 as the replacement part for 902s...Quote:
Originally Posted by voice of the theater
Also, has anyone done an A/B compare of the GPA 902 and the 902 with the original lightweight fram?
The vast majority of 902-8A's were originally equipped with Altec 34647 diaphragms. That was the original "stock" part for those drivers. It's the same 34647 diaphragm that GPA manufactures today. So your drivers do appear to have their original diaphragms still installed (same as mine). From what I've heard, some of the very first 902-8A's may have come with the "light" diaphragm that was the "stock" diaphragm for the 802-8G drivers. That was an Altec 23744 diaphragm.Quote:
Originally Posted by Alien_Shore
I've been busy with a bunch of other stuff, but here's a teaser of my messy desk. My Model-14 refurb project is still alive.
https://live.staticflickr.com/65535/...8cb16482fc.jpg
OK, the first prototype is complete.
https://www.hostboard.com/forums/hbm.../2012/07/1.jpgxo prototype
This is a modified version of the Richard C Model 14 crossover with zobel on the LF side.
https://live.staticflickr.com/65535/...e712fc71_c.jpgRichard C M14 redesign xover
Gonna go upstairs and do an A/B comparison to the stock XO.
XO test #1
Here we are in the home gym / entertainment place...
A/B comparison:
https://live.staticflickr.com/65535/...7433fa1603.jpg
The XO test rig:
https://live.staticflickr.com/65535/...53ea07bc59.jpg
Results:
Epic fail. The fatigued, 33 year old stock crossover sounds better. :rolleyes:
The new crossover is very flat. It does have a great crossover point and smoother mids, but lacks the definition and punch at the low end and nice sparkling highs of the stock XO.
So much for outsmarting the smart guys, eh? So it's back to the drawing board. I've never used the copper foil coils before, maybe this has something to do with it.
Next step might be to emulate the stock with all new parts and see how that sounds.
If your bored you could always try what I did, a simple 1st order crossover. I'm so happy with how my speakers sound now I could just...poop. :)
Personally, I'm not surprised that the original crossovers beat out attempts to "best" them. Once I re-capped my Model 14 Crossovers with Solen "fast caps" I was blown away by the sound of those 14's. There's a thread here somewhere about my recap......Quote:
Originally Posted by Alien_Shore
That's why I always continue to use the original coils/inductors that came with Altecs crossovers, and just replace the old caps and resistors.Clean the pots/L-pads and move on to the next project... Replacing the old caps that are 25-30+ years old really makes a huge difference IMO & experiences... And is really all that is needed.It's been 30 years since these old classics have been manufactured thereabouts and in that time there has really been no magic bullet of a crossover tweak (Passive) so to speak.And for good reason most of Altecs good crossovers Model 19/604H's were top notch designs.Of course there are exceptions that weren't so good.But for the most part just replacing the caps is all you really need to do IMHO.
I wish Earl was still around. I'd love to pick his brain about what makes those designs so good. Not to mention, I'm wondering about those old inductors they used...I am definitely going to test some variations around using original coils, new caps/ new inductors, new caps/ etc. I put together the schematic for my M14 crossovers this evening for giggles.
https://live.staticflickr.com/65535/...67ba6d7134.jpg
I should have my L/C built by next week sometime, then I can confirm the inductance values of all the coils.
Do you mean Earl K?Quote:
Originally Posted by Alien_Shore
Yes, I am also asking the same.
Do you mean Earl K ?
IIRC Earl's (Earl K) work takes him out of town for long periods quite a bit.But he doesn't post here that often anyway.He posts more frequently over at Lansing Heritage.
Many thanks AB for the clarification.......
Quote:
Originally Posted by Alien_Shore
It is really nice to see that so quickly you have started to suspect ( rather appreciate ) these old inductors. I will tell you (and everybody else) not to lose these,and to preserve them, as these inductors were part of a 30/40 yr old design frequency-shaping circuit. It wil be very difficult to duplicate them today. Inductors used in the mains ckts are not important, as they can be easily duplicated, but not these.
I remember reading a small story in the late 80's/early 90's issues of the "studio sound" magazine. It was about the famous API-550A equalizers, which used a simple two stage transistor amplifier with the output being loaded with a trafo, from which the feedbacks were taken for the frequency shaping purposes, via a muti-way switch. As API was closing/closed due to financial troubles, somebody (he was a big tech head of that time) wanted to replace the existing 550A circuitary with more modern high end components, (as the 550A innards were very clumsy and dirty looking) and continue selling them. But they never succeeded, even after trying it for two yrs., and the original output trafo could not be duplicated. They just could not duplicate the sonic quality of the original 550 equalizer.
Yes, I meant Earl K, the crossover wizard.
I recently picked up a pair of crossovers that were parted out of a pair of 9842s. I think what I'll do is use them for the components and work on some tests.
At this point, I doubt that the M14s can be improved upon, short of driver refubs and replacing oxidized caps in the stock XO design. I have done a TON of reading on this, and it is still amazing to me that so little is published about how these XO designs truly work. It is apparent to my old, rusty ears though that the entire package was very carefully designed to work together. If only such dedicated engineering and manufacturing still existed.
It does ! You just have to pay a ton of money for it these days....Quote:
Originally Posted by Alien_Shore
Managed to squeeze in another bit of testing this evening before dinner:
https://live.staticflickr.com/65535/...5384878b7f.jpg
the 902 in the left side is definitely lacking. So I put a 908-8A on there with a spare horn. MAGIC.
Now to just figure out how to fit that sucker into the cabinet :D
Why not mount the 908 on the Manta..This will give you the opportunity to examine the 902 to see what is wrong with it.
Good thinking, AB...did just that very thing. In fact, I toyed around with several drivers on some spare MR horns. Also, I rebuilt the prototype XO, using the inductor and L-pads from the 9842 XO, and all new caps - playing around a bit with the values.Quote:
Originally Posted by Altec Best
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This is getting much better now. The prototype left channel is now sounding better than the stock right channel. Progress! :Thumbs up:
I need to get a measuring program for my laptop. Any suggestions out there for something that is accurate but doesn't cost an arm/leg?
Congratulations on your progress :Thumbs up:Quote:
Originally Posted by Alien_Shore
I use a db-meter, and the free version of ARTA for my measurement work. The free version can do everything except saving a graph, and is not fussy about the sound card also.
ARTA Download
After a couple attempts at getting an L/C meter that would work accurately with these multi-layer coils, I have some fairly reliable measurements of the coil in the Model 14 crossover. So here's the updated schematic. I'll measure some of the other crossovers I have later this week.
https://live.staticflickr.com/65535/...ba6d7134_c.jpgModel 14 XO schematic
For what it's worth, the 4 crossovers I have all measure a bit differently, but that's predictable given the tolerances of these devices. I'm feeling pretty good about the 0.21 mH being the average across the ones I have.
So in the process of updating these crossovers, I decided to test the woofers. Here's the comparison of the two:
This first one is looking and sounding pretty good.
https://live.staticflickr.com/65535/...225489af14.jpg
Something is off with this one. The Re is low, and a big difference in the impedance plots.
https://live.staticflickr.com/65535/...d8339d4984.jpg
Anyone got any insights? I think the second one may need a trip to OKC...
Talked to Bill @ GPA today. He said there's something "definitely not right" with that woofer. I'll be packing it up and sending Monday.
Until then, I'll be playing with my newest tool in the arsenal:
https://live.staticflickr.com/65535/...2d58686e07.jpg
I picked up a Behringer Ultradrive Pro. Wow. This thing changes everything. It's amazing to me how much different the sounds are with the different filter types, and slope of the crossovers. I have a lot to learn... :emot22:
OK - I've taken the plunge and got a test rig up and running.
Here are some of the results - you guys go easy on me - I'm a noob on this measurement stuff.
All measurements done in-cabinet, on-axis, and near-field (mic right up next to the driver):
Cabinet 1 Woofer:
https://live.staticflickr.com/65535/...55b9da81f3.jpg
Cabinet 2 Woofer:
https://live.staticflickr.com/65535/...dff130d70e.jpg
Cabinet 1 HF Driver:
https://live.staticflickr.com/65535/...12eb6b2fe3.jpg
Cabinet 2 HF Driver:
https://live.staticflickr.com/65535/...2d06b70357.jpg
Definitely looks like I have a problem with one of the 902's, or maybe I screwed up the measurement somehow.
Evolving the technique:
Cabinet #1:
https://live.staticflickr.com/65535/...4752291b52.jpg
Cabinet #2:
https://live.staticflickr.com/65535/...0aa1a54181.jpg
Since I was taking apart the cabinets to pull the speakers out to send off to GPA, I did some physical measurements of the dimensions of the Model 14 cabinet. I couldn't find a drawing of this cabinet online anywhere so I sketched up a quick drawing:
https://live.staticflickr.com/65535/...2c13f0fb90.jpg
https://live.staticflickr.com/65535/...0aa1335abf.jpg
There are more details needed to actually construct on of these cabinets. Perhaps I'll add to this if the need arises.
OK, while I wait for the woofers to be "GPA'd", I needed to work on these cabinets.
Several things are in obvious need of repair. I started with the base cabinets:
https://live.staticflickr.com/65535/...b84f7ecce2.jpg
They all have some refinishing issues, but there are some structural problems too. First off, there was a woofer mounting bolt missing. Turns out that there was a big chuck of particle board broken away and the tee-nut was gone as well. In case you're wondering, the bolts are 1/4-20 x 1 in. (finished in a lovely dark color). The tee-nut obviously is a 1/4-20 thread (more on the parts later). First thing was to take some industrial strength wood filler and patch the hole. You can see right there at six-oclock, this is after 3 applications and sanding in-between. It actually filled in pretty nicely:
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There was a similar issue with one of the cabinet tops where the horns mount. One of the horn mounting bolts was just turning the tee-nut. Turns out it was cross-threaded like never-before-seen. I asked Bill @ GPA for some advice and finally got both the bolt and the tee-nut out without damaging the horn. The repair job was similar to the base cabinet - wood filler, sand, repeat.
The snazzy knurled bolts for the horn (and the crossover) are socket head bolts (you can find these at home depot online - not available in retail stores near me anyway). I couldn't find the woofer mounting bolts anywhere, so I figured what I would do is convert them all to socket head bolts so I can just use the same tool to remove the horns and the woofers, plus they look very cool. So here is the hardware I'm using for the repairs:
Per speaker -
(6) #10-32 x 1" steel socket cap screws (MR931 horn bolts)
(8) 1/4-20 x 1" steel socket cap screws (Woofer bolts)
(1) 1/4-20 Brad hole tee-nut
(1) #10-32 Brad hole tee-nut
(8) Shepherd 1-1/8 in. Plastic Base Nail-On Cushion Glides (for the foot)
https://live.staticflickr.com/65535/...b257e506cc.jpg
With the holes patched, and the new tee-nuts installed, it was time to do the re-finishing. I scanned this site for the recommended stuff. Howards Restor-a-Finish gets the nod. I also picked up the Howards Feed-N-Wax. Let me tell you, this stuff is unreal! Talk about easy, no-mess, and fantastic results. I'll let the pictures tell the story. Here is the top-cabinet before I started - lots of water stains, sun damage, etc.:
https://live.staticflickr.com/65535/...c214f13980.jpg
Then comes the Restor-A-Finish (I'll start calling "Jesus in a can") you just slather this stuff on and rub it in for a few minutes with a soft cloth:
https://live.staticflickr.com/65535/...25d6e8ec08.jpg
Twenty minutes later you just wipe it down:
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As if it didn't look dramatically improved enough already, just rub in some of the Feed-N-Wax ("Apostles in a bottle"):
https://live.staticflickr.com/65535/...e47a468f04.jpg
Holy divine furniture re-finisher, batman! Unbelievable. This stuff is highly recommended... A+!
OK, on to the pedicure. The feet of these 30+ year olds were looking rough:
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I figured what I'd do is tear off the crappy particle board feet, and replace them with hardwood. The nearby Lowes had some nice oak 2x2's...that'll do just great. I cut them to size (18" x 14" in case you're wondering), glued and screwed. Here they are in the jig waiting for the glue to dry:
https://live.staticflickr.com/65535/...51a7cf86ab.jpg
Stay tuned, as the epic M14 refurb continues...and thanks for watching.
Wow--great job Allen! Those 14's are coming along nicely. They're sure to look as great as they sound now......
