Crossover Help Needed With ANOTHER Pair of ALTECS

[Earl K]

Richard C is certainly the man when it comes to practical Model 14 info .

Unfortunately his personal web-page is no-more .
He still maintains a photo-bucket account ( with good info ) , here !


He has stated there were 3 basic M14 crossovers ( and then nicely provided proof with this pic ).



His comments about the M14 sounding like his M19s were made after he redesigned the original crossover to this ;




- ( it's no surprise the "voicing" of the M14 became closer to that of the M19 /// his schematic clearly owes its design origins to the M19s network )

- FWIW, previous to his new networks being implemented ( he commented that ) he found the sound of the stock M14 to be fairly fatiguing ( according to some posts I read ) .

- Based on his experience, ( & if these were mine ), I'd be building up a pair of fully new crossovers ( not just recapping ) .

<> EarlK

ps ; here's the same schematic showing voltage drive ( for the HF section ) of Richards redesigned network ;

[Earl K]

I had saved some of Richard C's original network studies onto an older computer .

Here they are ( with the Model 15s schematic thrown in as a bonus ) .

(A) First, 2 flavours of the M14s original network minus the protection circuitry.





(B) Then Richards' redesigned network .



(C) Then the Model 15 stock network .




<> EarlK

[Earl K]

Read this thread to understand why Richard went to all this work to create new networks for his M14s .

Here's an excerpt ;

With that said "IF I didn't somehow know that there was great potential in my Model 14's - I would have sold them after 5 minutes of listening". I felt sick for awhile! All the time gathering up components and researching. I couldn't believe that anyone would listen to these without major work. The upper mids were way too bright, so I got my Stereophile test CD, a tripod, a SPL meter. I measured the response at about 10' (where I listen in my room). I immediatly found that what I heard, I could also see.

CLASSIC !

- I'm confident that I would share the same reaction when listening to a network clearly designed for either P.A. or Theatre installs ( no real VHF ) .

<> cheers

[voice of the theater]

Earl, thank you for posting these photos/schematics!! You really came through for me!! From the photo you provided, my Model 14 crossovers are clearly identical to the one on the left of the photo. In fact, one of mine has the purple 470 uF resistor (same color as in all 3 photos), and one has a grey 470 uF resistor which looks to be made by the same manufacturer who possibly changed color of their caps at a certain point in time from purple to grey?

Anyways, as far as Richard C's decision to build an entirely new crossover for his Model 14's--obviously I respect his ability to do so but I don't share his reason(s) for doing so. I really don't want to turn this thread into a debate of "whether or not to build a better mousetrap", because as is pretty much common knowledge, personal preferences (regarding which speakers/crossovers sound "best" to you) and psychoacoustics trump "paper and pen". All I can say is that I LOVE the way these stock crossovers sound. Richard complains about the midrange sound from the stock crossovers, but most people who've posted about them here and at AK who've heard Model 14's rave about the overall sound quality--and many rave about their midrange sound in particular (that vintage Altec midrange magic). Obviously, if Richard doesn't like their midrange sound--more power to him as far as building new crossovers, but he is the minority in his opinion (not that being in the minority makes him "wrong" of course--he apparently has unique tastes compared to numerous other posters who've heard these speakers). I'm sure he has a very good explanation as far as why building a new crossover that more closely resembles the Model 19 stock crossover might be a good idea--but my own admittedly empirical take on this would be that the Model 19 uses a VERY different woofer, VERY different horn, different h.f. driver, cabinet, tuning etc. (compared to the Model 19) and I would think that it might make sense to have a very different crossover design for the Model 14 as compared to the very different Model 19. Perhaps the only way the good folks at Altec could get the Model 14's to sound "right" to them, (considering the fact of how different they were from the 19's) was to use a crossover design that more closely resembles "a network clearly designed for either P.A. or Theatre installs". After all, presumably their goal (as you know 14's look just like "junior" 19's) was to build a smaller pair of speakers (compared to the 19's) that have an overall sound as close to as "good" as the 19's as possible (and IMHO, they succeeded based on my own A/B comparisons of Model 19's vs. 14's). Great sound is presumably the desired end result, not a crossover that resembles the Model 19 crossover--instead, a crossover that would work with these very different drivers and horns that would produce a similar great sounding speaker.....
Here's some new quotes from this hostboard that I found while reading the thread you pointed me at today (and from another Altec hostboard thread) that illustrate how much these people love the (midrange) sound of the 14's....

The 14's are much more like the classic Altec sound of clear midrange and remarkable efficiency. This is my first listen to a CD Mantaray horn. I am luvvin it. The spatial soundstage is precise and vivid. I have been playing a number of Cowboy Junkies tunes and Margo Timmons voice is ghostly-real.

Indeed, these speakers are fantastic sounding, far superior to the model 15's I also own. Despite the supposed handicap of their "plastic non-pro horns" they were an integral part of my studio set up along with some Dahlquist DQ10's and some Meyer powered enclosures. They are far more appropriate for the average sized room than the Model 19's which can quickly overwhelm the listener in such situations.

And the quotes from my previous post in this thread regarding 14's with stock crossovers

quoting Bowtie (page 1 of thread):
"Probably the next best sounding speaker to the model 19 where the late model home series is concerned, they will even impress non-Altec fans."

quoting daWoofer (page 2 of thread) "I would be pumped also. I remember well 25 years ago when I heard my first pair. Wish I had still bought them then, and wish I could get a deal on some today. Have fun."

Quote from Moorden2004 (who started the thread when he had a line on some 14's, and then found the woofers needed refoaming) Page 7 of thread... "
My cross-over pots were fine - no scratching nor intermittents. The new surround kits were dead easy to install (who knew?). And, like you, I'm amazed at the quality of the sound field. Solo guitars seem to be so close you can touch them. The bass is so clean and controlled I've shut down my Yamaha sub-woofer. Not needed. But it's the mid and high range from those horns that captivate you -- clearly a well designed driver/horn combo."

Moordon 2004 "In my very limited experience with these 14's I can concur that guitar and solo voice are startling! You can almost reach out and grab them -- or so it seems. Placement is interesting too. In my room they do like the no-wall-coupling position. Mine are 10" from the wall behind them and a few feet from the side walls. This seems to be ideal. My senses can't tell the difference with and without my powered sub (Yamaha) on, so that alone tells me plenty."
Paul

I firmly believe that by the time Altec had designed the Model 19 (a masterpiece, IMHO), they really had a handle on what it takes to get a speaker system to sound unbelievably good. They had (more) modern cabinet tuning by this time, tangerine phase plugs, more effective h.f. compensation in the crossover, "better" h.f. drivers, etc. (and apparently a real "feel" for what sounds great). In fact, after buying two pair of Model 19's, my prerequisite for my third pair of Altecs that I was shopping for was that it have the above ingredients. I truly believe it was those ingredients that set the 19's (and the 14's) apart from my 846A's, As 101's, all original A7's (I owned a mint pair of all original A7's back in the 90's), etc. I think the 15's were nice, but there is a reason they were replaced with the 14's (much better/more powerful woofer with 3" voice coil, better horn (Mantaray), etc.). One of the first things I did when I got my second pair of Model 19's home was set them up next to my first pair and do A/B comparisons to make sure the new pair sounded equally amazing to my first pair--and they do. (a photo from that day)

When I got my Model 14's home, I set them up right next to one pair of my Model 19's to do some A/B comparisons. Other than the fact that the 19's are a little more efficient (and therefore I had to provide a very slight power increase to the 14's to get them to play at the same level), they sound remarkably similar to both pair of Model 19's that I own. Yes, if you turn the midrange pot all the way up on the 19's, there is too much midrange--I turn the pot down a tad on them towards the "optimal" position. Same goes for the 14's. If you turn the midrange pot on them down a tad (I love how the 14's and 19's have a treble and midrange pot on them -- very unusual for two way speakers), the midrange sounds remarkable on them -- not any louder/honkier/etc. than the midrange on the 19's. They just plain sound amazing. The proof is in the pudding..... I would have to second the sentiment from Bowtie's quote earlier in this thread --"Probably the next best sounding speaker to the model 19 where the late model home series is concerned, they will even impress non-Altec fans." As an afterthought, I wonder if Richard C's 14's have the 23744 diaphragms--mine do. If his don't that could be a factor in how his 14's sound. However, I am inclined to believe it's more his personal taste, not his diaphragms. I'm not at all ungrateful for your input Earl, quite the contrary, I am unbelievably grateful for your sharing the photos, schematics, info, and uncensored opinions with me. We may have to just agree to disagree as far as the merit of building a better mousetrap. If you could hear these 14's (if I set them up right next to a pair of my 19's for you), you might just say that based on the sound of this amazing speaker system, that you agree with me (and with most people who've heard the 14's that have posted here and at AK) that just like the 19's, Altec really got it right when they designed/built the 14's.

[voice of the theater]

Here's the schematic that shows the 10 uF and 2 uF capacitors.

Seems like you have a pretty good handle on the capacitor replacement.

So, westend, Earl K, or GM, (or anyone else who wants to chime in), I'm correct in my asumption that these are the two capacitors shown in the schematic above (I can read 2 uF, and 10 uF on them), and that they are indeed capacitors, and that they are the two capacitors I should focus on as far as replacement (not worry about the 470 uF capacitor)?

I would also replace the electrolytic caps because of their age and the low price for quality replacements.

Thanks for the heads up! These crossovers sound great now--if I hear a noticeable improvement after putting in the two Solens, I may at that point decide to delve into the electrolytics and resistors. Unlike the Model 19 crossovers, it appears to be easier to do these in stages if I decide to--whereas with the 19's I'd have to remove the newly installed capacitors if I wanted to go back later and replace the resistors..... From what I understand, resistors are less vulnerable/subject to changes in value compared to capacitors so they are not my top priority in the 14's crossovers at this point....

I would definitely try to mount the new caps in the through holes. If you haven't had at it with solder wick, this is probably a good learning platform, lot's of free space, lead count low, and I would assume the board is amenable to the work.

I've never used a solder wick--and this is not a good learning platform for me. I'd like to learn (and make my mistakes) on a Sparkomatic crossover! That would be a good learning platform----not on my Altecs. If you ask my wife, on certain days she probably thinks I love my Altecs more than her..... If I fry something on these crossovers due to a mistake, she had better remove all the breakables from the house :doh: I gave the short version of how I found these Model 14's earlier in this thread (if you can believe anything I post is capable of being a short version!). The long version is that the pair I bought (6 hour round trip drive) was actually the SECOND pair of Model 14's I auditioned. The first pair was close to Philadelphia (9 hour round trip drive). I drove 4 1/2 hours to get there, the guy had insisted these were mint. I got there (brought my own amp and CD player and CD's), turned them on and one horn was very muffled sounding compared to the other. To make matters worse, one woofer was louder than the other as well. I figured a GPA recone would fix the woofer, but had no idea what was going on with the crossovers/drivers/diaphragms as far as what was wrong with the muffled high end. We actually swapped out crossovers on my request and it didn't swap the problem so it wasn't the crossovers. But I did the math, with his asking price plus woofer recone plus two new diaphragms or two new hf drivers from GPA I'd be paying WAY more than the speakers are worth. I know I'd never be happy buying one diaphragm or one h.f. driver. The first thing I do when I audition a pair of speakers is A/B them and they have to sound identical to each other for me to be happy. If not, they'd at least have to be inexpensive enough for me to be able to justify buying a pair of diaphragms or h.f. drivers, etc. I know buying one diaphragm or one h.f. driver just wouldn't work for me--it will (almost) never sound identical to it's (30 + year old) mate so I have to buy stuff like that in pairs. Luckily, both pair of my Model 19's and the Model 14's I ended up buying later were identical sounding pairs. Anyways, I drove home very p*ssed off, to say the least. The point I'm getting at, is that I finally have the speaker collection I want (two pair of 19's and a pair of 14's). All the buying and selling/upgrading that got me to this point had it's ups and downs. I don't want to buy any more speakers (maybe EVER--I'm that happy with the three pair I own). So, if I fry a crossover and have to scour ebay / craigslist for a crossover (and hope it's the "right" version of the three they made for the 14's--I really like how this version sounds), I'll be crying in my cheerios.

That being said, is it acceptable (although I know it's probably not the best way) to just clip the leads from the old caps while being sure to leave enough of the old leads to allow me to just solder the new caps to them (solder the leads of the new caps to the portion of the old leads I leave intact/attached to the board)?

Should I use lead free solder? Any recommendations from anyone on solder? Should it have silver in it? (don't want a solder wars thread but a recommendation would be helpful!) Thanks again to EVERYONE, time for me to shovel some snow.....

[RonSSS]

Do not use Lead Free solder. It's a pain in the butt and requires a lot more heat. Your speakers do not need to be ROHS compliant.
I would use solder with either 2 or 3% silver.

Ron

[voice of the theater]

Great Ron--thanks for the tip! Do you (or anyone else) have any answers for the few questions in my last post (other than that question)?
P.S. If only "We're An American Band" by GFR had more cowbell in it!!!

[Earl K]

Earl, thank you for posting these photos/schematics!! You really came through for me!!

You're welcome .

I'll respond later to a few of the things that you brought up , perhaps tomorrow morning .

So, westend, Earl K, or GM, (or anyone else who wants to chime in), I'm correct in my asumption that these are the two capacitors shown in the schematic above (I can read 2 uF, and 10 uF on them), and that they are indeed capacitors, and that they are the two capacitors I should focus on as far as replacement (not worry about the 470 uF capacitor)?

Yes the 2 caps in this picture are the ones represented within Richards' schematic .



I wouldn't just cut the leads to the caps ( I prefer to save these things with all the leads intact ).
FWIW, IME, they are pretty decent sounding ( ie ; quite mellow when compared to any plastic film type ) .

I would remove them in one piece and set them aside .

<> cheers

[voice of the theater]

Well--five and a half years later, I've decided I want to experiment with my Model 14 crossovers. When I did this recap in January of 2011, I wanted to replace the 30 year old caps with new caps of the exact same values as I did for both pair of my Model 19's and other Altecs I've recapped in the past. However, in the case of Model 14's, Altec manufactured three variations of the Model 14 crossovers--so if they rethought their design, I'm thinking that maybe I should try one of the other factory designs to see if I like it better than the one I'm now using. My 14's came with the 2 uF and 10 uF combination. If I'm reading Richard C's diagrams correctly, it looks like there was a factory version that used a 2 uF and 6 uF combination. I have three questions before I start my "experiment".

1) Are the two Altec factory designed networks identical other than the 2 uF / 10 uF combination being swapped for a 2 uF / 6 uF combination? In other words, if I swap out 10 uF cap for a 6 uF cap, will that convert my crossover to the other Model 14 variation that Altec manufactured, or are other changes involved as well?

2) I do have to turn down the midrange EQ "pot" on my Model 14 crossovers quite a bit to get them to sound their best. If I swap out the 10 uF cap for a 6 uF cap, will that result in less midrange from the Model 14 system (which would mean, among other things, that I won't have to turn the midrange pot on the crossover down as far)?

3) Does anyone know what the third variation of the Model 14 crossover was comprised of? Richard posted a photo of all three stock Model 14 crossovers, but only did a diagram for two of them?

To assist in the answering of these three questions, here's a photo of the three stock crossovers from Richard's photobucket page. Model 14 x-overs.jpg

Here's a link to Richard's photobucket page which has the above photo plus a bunch of crossover "schematics".

http://feed266.photobucket.com/album...io/account.rss

I'd really like to try at least one of the stock Model 14 designs that Altec manufactured and compare it to the stock version that mine came with to see which I prefer....

I had saved some of Richard C's original network studies onto an older computer .

Here they are ( with the Model 15s schematic thrown in as a bonus ) .

(A) First, 2 flavours of the M14s original network minus the protection circuitry.





(B) Then Richards' redesigned network .



(C) Then the Model 15 stock network .




<> EarlK

[Earl K]

( "Right-Click" ) the pic & open in a separate tab, to see it's full size .



The HF output ( ie; voltage-drive ) is displayed within the smaller window ( called the "Bode-Plotter" ).

The cursor within that window is set to around 2K.

One can see that the 6uF variant of this network employs a ( restorative ) response peak at around 2K ( right near the x-over point ).

I'd need to see some raw measurements of the speaker before commenting on whether the peak is truly needed.

All you can do is try this variant and see if you like it .