Crossover Help Needed With ANOTHER Pair of ALTECS

Impedance.

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Originally Posted by Earl K

Here's the un-equalized response of the M14's horn-driver combo .

One can see that it needs the mid-range suppressed by some 6 to 10db ( between 1-6K ) so that the HF ( above 6K ) is brought back into a more reasonable balance .

http://www.hostboard.com/forums/hbmc.../2016/06/2.png

:)

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Thanks Earl and Bowtie!
Attachment 3037
Looking at Richard's photo of the three Model 14 factory crossover variations, it looks like the one on the far right has two solid core inductors whereas the other two variations have only one inductor (mine is the one on the far left). Am I seeing this right? The one on the right is the one that uses a 6 uF capacitor instead of the 10 uF that my version uses. Richard has provided a schematic for my version (the 10 uF version) and also for the 6 uF version. Is there anything in his schematic that indicates an extra inductor for the 6 uF version? (I can't read schematics!)

Hi vott,

The second coil ( shown as .667mh in your picture on the rightside ) is represented in this schematic ( as the .67mH coil ) within the HF leg of the network .

It ( along with the values of the caps near it in the circuit ) is partly responsible for that peaking seen at 2K (within the Bode Plotter window).

http://www.hostboard.com/forums/hbmc.../2011/01/2.png

:)

Quote:

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Originally Posted by voice of the theater

Great idea--there's no way that I need the protection circuitry as these speakers are so efficient I doubt if I ever put much more than 10 watts per channel through them--they blow you out of the room if you go past that. Anyone out there know how to bypass the protection circuitry? I doubt if it will effect the sound but it just makes sense to not have the signal go through any more circuitry than is necessary.... Not sure if this schematic will help as it leaves out the protection circuitry..... (click on images for full size)
http://www.hostboard.com/forums/hbmc.../2011/01/5.png

http://www.hostboard.com/forums/hbmc...2011/01/22.jpg

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OK, I asked if anyone out there knew how to bypass the Model 14 crossover protection circuitry FIVE AND A HALF YEARS AGO (in this same thread--see above quote) AND I GOT AN ANSWER THIS WEEK! lol I guess patience really is a virtue. This forum has been SO helpful with me learning how to optimize, update, and recap etc. my Model 19's, Model 14's, and Santana II's--this is the first question I've ever asked here (that I can remember anyways) that "stumped the panel" for five and a half years. Well, I finally got my answer from (user name) Lansing 4112 who is part of the Audiophile Nirvana team. He sent me this link in response to my question:

Model 14 Mods - Audiophile Nirvana

I have finally bypassed the protection circuitry in my Model 14 crossovers! In post number 56 of this thread (page 6 of thread) I comment on how much better my Model 14's sound after recapping the crossovers with Solen caps (thanks to help from Earl K, GM, Altec Best, Aditya, etc. etc.). I comment on how the high end and clarity are both significantly/noticeably improved after replacing the 30 year old caps!

Well, now that I've finally bypassed the protection circuitry on the Model 14 crossovers, this week, I am happy to report that these things sound even better without having the signal pass through that 35 year old protection circuitry. There is a lot to that circuit--a good chunk of these crossovers (much of the electronic circuitry) comprises the protection circuitry. By bypassing it, I am left with just the basic crossover circuitry--much less unnecessary "gobbledygook" (technical term) for the signal to pass through. I am really impressed that the 14's now have even greater clarity (and they just plain sound clearer/cleaner) and a more defined sound than they did before the "bypass"! Also, very surprising, I'm getting more low end out of them. Apparently, having the signal pass through the 35 year old protection circuitry was having a derogatory effect on the low end of these speakers. I said after I re-capped the 14's that they rival my two pair of Model 19's. I did some extensive listening last night and this morning after completing this bypass, and with the increased clarity/more defined sound and enhanced (restored) low end from this bypass, it is now too close to call IMO which speakers sound best on most recordings--the 19's or the 14's. In fact, there are a couple of recordings that I did an A/B comparison (same song on the 14's and 19's) where the 14's actually bested the 19's! That has never been the case prior to this bypass--up until now the 14's at best sounded comparable (but different) to the 19's on some recordings and inferior on others. Now, post bypass (and of course 5 years post recap), I have recordings that sound better on the 19's, some that sound better on the 14's, and many that are too close to call---they sound amazing on both the 14's and 19's and it's really a tough call which speakers most recordings sound "better" on! THANK YOU TO EVERYONE HERE WHO HAS HELPED ME ON THIS JOURNEY WITH THESE AMAZING SPEAKERS!

Attachment 3058Attachment 3059Attachment 3060
PICS OF BYPASS (1st pic is pre bypass, 2nd and 3rd are the two crossovers bypassed) As you can see, I've recapped these crossovers with Solens, and have bypassed the treble "pot" to reduce the amount of circuitry the signal passes through since the optimal range for the treble pot, according to Altec, is in the maximum range and they do sound best with that pot turned "all the way up". I use the mid pots so those are still connected---in their optimal range (about halfway up), the balance of bass to mid to treble is excellent. In a recent thread in this forum, someone asked which of the three versions of the Model 14 stock crossover sounds best, based on reports I've heard of some of the versions of this crossover sounding too "shouty", I'd say this version is probably the best. Sounds AMAZING! (this version is the one with the 10 uF and 2 uF caps)

Thanks guys, after more study, I think I have a plan to update my series 1's to match the series 2 crossover ( 2uf & 10uf cap)

Earl K, the schematics and measurements are a big help. If I loose the .67mh coil it looks as if the nasty peak at 2k will drop a bit. I will also change out the caps. To series 2 values.

Voice of the theater, thanks for the the listening notes and comparisons. Helps verify that smooth rise is actually preferred.

As much as I appreciate the guys restoring and reviewing a pair of 14's, I think they may have been using the 1st gen crossover with the "restorative peak" for their listening before going active.

Looks like the Altec team did indeed improve the design in the later gen 2 versions. Nice to know. :D

Quote:

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Originally Posted by voice of the theater

Thanks for the link GM--excellent thread! I'm not an AK member so I couldn't access any of the AK links or the "quote" feature, but I read the entire thread and there was a lot of interesting info there--and some familiar names as well--Bowtie, Analog Addict, Zilch, etc.....

It seems most people who've heard or own the Model 14's love them:

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 Richard C. (page 2 of thread) "My Altec 19's are downstairs, but my model 14's are my main living room speakers - cause they fit better! The sound is similar, and most people are impressed by my 14's sound."

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."

And there are some people later on in the thread trying to figure out how the crossovers work and they're not sure they approve of the design. But I've heard the same type of conjecture about the Model 19 crossover design and I really believe that Altec "got it right" when they designed the Model 14's (and 19's) so I'd like to duplicate the original crossover by replacing the old caps with new ones of equal value. I think if you heard these things (psychoacoustics), you'd agree. I really like the h.f. compensation in both crossovers (compared to the older Altec crossovers I've owned), combined with the 802G and 902-8A driver and the tangerine phase plug, tuning of the cabs etc,--a "magic" combination IMHO for both the 14's and 19's.

Now that being said, obviously nothing is absolutely perfect. In fact, a wise man once said,





After owning these Model 14's for a while, I can see the truth in your quotes. I consider Model 14's and 19's to be an apple and oranges comparison--not necessarily cut and dry better or worse. I'd say the high end in the 14's is easily equal to the Model 19's--the 902-8A h.f. drivers sound amazing combined with the Mantaray horn. And I have to admit, I've owned mainly 811B and 511B horns and was skeptical about the Mantaray--that is, until I heard it. It's sound quality in conjunction with the 902-8A is on par with the Model 19's, but it's dispersion characteristics are much better for my living room (where I have them located). I have a long couch and a love seat in that room--and you can sit ANYWHERE on the couch or love seat and the high end sounds amazing--there is a much wider sweet spot compared to the 811B or 511B Altec horns. Hopefully this doesn't sound like sacrilege to anyone--I'm not saying the 14's have a better high frequency response/sound compared to the 19's, just better dispersion characteristics (which is only beneficial in certain applications--like my living room since it's not a particularly huge room, for example).

As far as bass response, with all other things equal (acoustics, EQ settings on your amp/equalizer, etc.) IMHO, the 19's win. However, I've found that by adding a little extra EQ in the 30-40hz range, the 14's rival the 19's as far as low end sound quality at the volume levels that I listen to them at. I'm sure that if I were to crank them up to an extremely loud level, the 19's, having 15" woofers, would win over the 14's (with 13.5" frame woofers) at any EQ setting. I do crank them up to what I consider to be very loud on occasion, and even at those levels with a little extra bass EQ at the 30-40 hz range, they rival the 19's in bass "sound"/response. The "interplay" between the woofer, cabinet tuning, and crossover is that good.

GM, here's where your two quotes come into play. As far as midrange, I have to give the Model 14's a slight edge (at least until I recap the 19's, then I'll have to compare again--although I plan on recapping the 14's as well!). I've got to think that it's because of what you said--which I roughly interpreted as meaning you're pushing the ("accurate/clean") upper frequency limits of most 15" woofers when your crossover point is 1200 hz. Yes, the 19's sound amazing, but there is a certain (subtle) clarity and presence that the 14's have over them in the midrange that is really only noticeable to me in certain recordings (it's a very slight/subtle difference as far as I can tell listening to mainly rock music--may be more or less noticeable with different genres of course). I've got to think it's due to the fact that the smaller woofer is more suited to reproducing the upper midrange frequencies (the Model 14's have a 1500 hz crossover point). In fact, in the AK thread that you linked me to people rave about the midrange "sound" from these speakers.

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."

Richard C "I especially like how guitar sounds on my 14's. Blues - Gov't Mule, Joe Bonnamassa, Clapton, Robin Trower, Dave Mason, etc. it cuts thru nice!"

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

Anyways, you get the idea. The people who listen to these speakers love them--hence my desire to not make any changes to the crossovers or drivers (other than "fresh" caps). Personally, if I were on a desert island (that had electricity!) and had to pick ONE pair of speakers, I'd pick the Model 19's over the Model 14's. They have an edge IMHO (and are big enough to be more easily converted into a life boat), but depending on the application I still think it can be an apple and oranges comparison. The highs are comparable (but the 14's have better dispersion characteristics), the mids in the 14's have a slight edge (probably the smaller woofer), but the 19's have a slight edge as far as low end unless you "tweak" your EQ for the 14's. I can honestly say, I prefer the 14's in my living room where h.f. dispersion is key due to the layout--the mids and bass sound great in that room as well. Downstairs, I love the 19's in my rec. room and in the recording studio. It will be interesting to see what new caps do to the h.f. response of the 14's (if I can get some help/schematic--HINT HINT!), and the h.f./mid response of the 19's (pretty much ready to go with their upgrade).......

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a deserted island with electricity, I am assuming food, water and plenty of music to play, I would just stay put.

Hello
I have the same problem
Can you explain me how bypass the protection?
Thanks a lot :-)

This link shows how to bypass the Model 14 protection circuitry. Model 14 Mods - Audiophile Nirvana

Quote:

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Originally Posted by Earl K

Here's the un-equalized response of the M14's horn-driver combo .

One can see that it needs the mid-range suppressed by some 6 to 10db ( between 1-6K ) so that the HF ( above 6K ) is brought back into a more reasonable balance .

http://www.hostboard.com/forums/hbmc.../2016/06/2.png

:)

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Hi Earl,

This is many years later, but I'm wondering if you could point me to the document that contained the FR/Impedance curve for the 902-8b/MR931 combo?

I'm also looking for a similar plot for the Model 14s 36633 woofer, if you happen to know where I might locate one?

Kind regards,

Sam

Hi Sam,

It's here > Altec MR931 Horn

:)