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What to do with Altec 420Y Drivers?

Do we believe for a minute that 420 plays to 14 kHz?

Bring them up here and I'll measure them. You'll know within 30 seconds what the rational replacement/upgrade path is.

If the original tweeters were crossed in the 1.2 - 2 kHz region, I would not be surprised. Using a 15" woofer above 800 Hz is a challenge, duo-flex notwithstanding.

Again, I don't know 420 from a hole in the ground, but 14 kHz is very likely pure fantasy, and from my own experience, Altec (and lots of others, as well) was not above playing fast and loose with specs:
 
Do we believe for a minute that 420 plays to 14 kHz?
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Wasn't i very careful to say "claimed" response?............. LOL

But, i do believe it plays well thru the mid band to 7000 or better with a sound that's very easy to like, not saying they're flat, just pleasant to listen to.

FWIW, santana which uses a 420 with the same or extremely similar tweeter baffle mounted is crossed at 2500. What makes a 420 a "Y" version is the coaxially mounted tweeter. There are no available factory sheets for the 420Y that i'm aware of. It would be nice to know what the original intended crossover frequency was.

Doesn't a 14uF series cap seem a bit large/low for a 3 inch paper cone sealed back tweeter?
 
bowtie427ss said:
Doesn't a 14uF series cap seem a bit large/low for a 3 inch paper cone sealed back tweeter?
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Does to me, yes, unless it's actually a 4-Ohm tweeter.... :dunno:

Well, you see where I'm coming from: If the intent is for these to become mains, as stated, get the facts - measure.

Garage speakers are another matter.... :p:

bowtie427ss said:
But, i do believe it plays well thru the mid band to 7000 or better with a sound that's very easy to like, not saying they're flat, just pleasant to listen to.
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Perhaps so (I'm thinking 755A here, which DOES actually play that high,) but if I'm understanding this correctly, there is no lowpass on the woofer; the tweeter is just riding on top of (and interfering with) whatever it's playing in that frequency range.

ICK! :(
 
I have a pair of CTS tweeters from santana's that measure a DCR of 6.1 on the ole fluke. The remainder of them including the 420's are long gone flood victims, so i don't know what they used as far as cap value just the stated 2500hz XO frequency.

To say that the 420Y in MX's speakers would use the same tweeter and XO point would be pure assumption, yet still somewhat supported as Altec didn't use very many different tweeters and made only a couple themselves.
 
Thanks Mac!

I remembered seeing that thread but couldn't remember if it was here at AK or elsewhere, and i surely didn't realize they were your's.

Thanks for posting!
 
Zilch said:
If the original tweeters were crossed in the 1.2 - 2 kHz region, I would not be surprised. Using a 15" woofer above 800 Hz is a challenge, duo-flex notwithstanding.
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Duo-flex is the key. What happens, is what acts like a 15" woofer up to about 1-2 KHz, effectively "decouples" the outer ring above that, and acts like a much smaller driver. In that case, it can go significantly higher. Given that I've measured reasonably flat (as in, it's not gone "off the cliff" yet) response from a D130 15" up to 6500 Hz on-axis... I could believe that the 420Y could easily go that high. Yes, it's a question of how flat (dips/peaks/breakup modes/etc), but it very likely MIGHT have usable output up there...

14KHz, OTOH... I have my doubts. The dustcap MIGHT act as a tweeter dome up there, but I doubt that it's anywhere near enough output to make for flat response...

Regards,
Gordon.
 
macaltec said:
For reference to those that may have not checked yet:
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Thanks, Mac!

Dealing with similar issues in Bauhausler's Aristocrat thread:

http://audiokarma.org/forums/showthread.php?t=115253&highlight=Aristocrat

And a couple of others, as well, recently.

I took particular note of the Bolero horn suggestion.

Where's the :banghead: icon? :p:

GordonW said:
The dustcap MIGHT act as a tweeter dome up there, but I doubt that it's anywhere near enough output to make for flat response....
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420Y's also apparently a coax, Gordon, which would effective shadow any on-axis HF from the dome, I would think.... :dunno:
 
You are welcome guys. SS those are actually Analog Addicts speakers. I myself have a set of Frankentanas that I used a Motorola piezo in that worked out quite well. It may be a viable option here as well. I'll dig up a link for that as well.

*EDIT* Here we go: http://www.audiokarma.org/forums/showthread.php?t=79659&highlight=piezo&page=2 My additions start at post 28 but the whole thread is a good read. I still pull these speakers out and give em a listen every week or so. I think the tweeters may have some merit on this project as well.

**EDIT, EDIT** I keep forgetting these are the coaxial variety. I am approaching it from a "mount it in the cab" standpoint.
 
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Jeez, I really don't know what to do. I keep going back and forth between cheap tweeters and horns. I don't know if horns for these are going to be the best bang for my buck, or if I should look for another pair of speakers instead.
 
mxlews said:
Jeez, I really don't know what to do. I keep going back and forth between cheap tweeters and horns. I don't know if horns for these are going to be the best bang for my buck, or if I should look for another pair of speakers instead.
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Firts thing I'd do is haul them up to Zilch's magic lab and see what you have to work with. Then find a tweeter that will work with it in the original mounting location. Keep the xo simple, maybe one from PE or Madisound. Then you can branch out to your other options if you desire more from the speakers. Mounting the tweet in the cab or finding some horns, all as money/time allows.
 
the cts 3t2 might be the model number for the tweet-
older fisher speakers have these



518
 
mxlews said:
Zilch, do you remember this thread?

http://www.audiokarma.org/forums/showthread.php?t=107477

I still have those cabs in the garage. Which would be better to invest in, the JBL's or these Altecs?
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The JBL clones have the advantages of replaceable baffles and restorable vintage panache. You can put just about anything in them. Watch for what Jackgiff is doing with his Altec Santanas.

Your Altecs already have woofers and will be less expensive as a project. It may be possible to make them work as well. I don't know until I measure them. You can hear the JBLs at the same time....
 
Zilch said:
Watch for what Jackgiff is doing with his Altec Santanas.
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I finally got all the parts to build crossovers and filters for my two way Santana's. Since it will require cutting new baffles for them before installing everything, it seemed much simpler to test all the various parts using the horns on top of Lancer 55 cabinets. The LE14's will have a little more room in the Santana's, but this is pretty close.

One of the chokes used must have a shorted turn, because it has a large dip at the crossover frequency. I eliminated all the other parts by substitution, and the problem is in the choke. Back to Parts Express it goes on Monday. Another fine reason why having the ability to measure frequency response just makes sense. I probably wouldn't have caught that for some time without the RTA.

Pics below are of a speaker being tested, the crossovers and filter on top, the FR's of speaker 1, and speaker 2 with bad choke and with substitute choke, and finally what the crossover looked like with a 1 Mh and 1/2 Mh in series to replace the iron cored 1.5 Mh.
 

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Holy CRAPOLA, Jack!

It just doesn't come much better than that. :thmbsp:

You've got useable bass down to 30 Hz from LE14As in L55 cabinets. As you suggest, they'll play stronger and deeper down there in the larger Santanas. L55s themselves can do a bit better with retuning of the port.

As-is, you've got +/- 2.5 dB from 50 Hz to 20 kHz, looks like, 1/6 octave smoothed. That's studio monitor performance level.

I don't have to ask how they sound, 'cause I'm listening to the same right now, but others here would likely be interested in that part.... :yes:

[I see that resistor hanging across the driver. Heh, heh....]
 
Zilch said:
Holy CRAPOLA, Jack!

It just doesn't come much better than that. :thmbsp:


[I see that resistor hanging across the driver. Heh, heh....]
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Seems like your first statement pretty much sums up how it sounds. Myrna and I spent some time last night listening before they were measured today. We really enjoyed them, but tonight will obviously be even better. The highs were set a little too high, and with the dip in the FR on one speaker gone, it will be audio nirvanha tonight.

It seems the BMS driver is so much more sensitive than the LE14A's, that it will need about 6-8 db reduction prior to the Lpad when installed in the Santana's. The FR's shown are with the Lpad almost bottomed out. That will be a simple fix when the baffles are done, and the components are installed. Can't wait. ...Have you ever heard me say that before?

I didn't install the series filter since Parts Express backordered the choke, but it doesn't seem to be a big deal. I can live with them exactly as they are. They are "GGGGREAT!!!

I didn't make provisions for a resistor across the driver in the printed circuit layouts of the crossover or the filter, so simply soldered it to the connectors. By the way, the connections for the BMS drivers needs to be reversed just like in the Altec 846A's.
 
jackgiff said:
It seems the BMS driver is so much more sensitive than the LE14A's, that it will need about 6-8 db reduction prior to the Lpad when installed in the Santana's.
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Yes. I added 10 dB fixed attenuation, and that puts the balance point about 1/3 the way down on the L-Pad.

And "Yes" on the polarity inversion for correct phasing, as well....

jackgiff said:
Seems like your first statement pretty much sums up how it sounds. They are "GGGGREAT!!!
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The major difference between these and your Valencias is the constant directivity waveguide, in which respect they are more like your big JBLs in producing uniform power response. These don't beam the high frequencies like the Altec 811B horns do, so you have considerably more latitude in listening position. Both the ambient and reverberant fields should also be more uniform.... :thmbsp:

jackgiff said:
I didn't install the series filter since Parts Express backordered the choke, but it doesn't seem to be a big deal.
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I'm pretty much convinced the spike at 19 kHz is breakup mode distortion, looking at the factory distortion curves, so even if it isn't apparent on the RTA, it's probably worthwhile knocking that down with the serial notch.... :yes:
 
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