ALtec Model 19-XO upgrade discussion

[Gary L]

This discussion was moved from another thread and might be a good one for here in the DIY section.
Many have tried numerous upgrades on the 19 XO with varying results.
Lets discuss what you have done and what the results have been.
I will start it from my very basic knowledge with a photo of the XOs built for me by member PaulC. I am sure he will join this discussion and hope to see Zilch, Dwojo, Dylan, Tom Brennan, RonSS and all you others who have interests in this area.
Here is what PaulC built for me.
Jeff Markwalts schematic was most helpful here and his input could be most valuable for this discussion.



Gary

[Dylanl]

All that I upgraded was the caps becuase I didn't want to change the flavor of the speaker. Lots of VooDoo about these X overs. Since the change, the mids and highs are cleaner but I have no way of measuring. Sorry if I keep boring you with this picture but it was what we were discussing

[Dylanl]

I have also listen to this passive pair on a friends set of 19's. My perception was better bass and similar mids and highs. If I remember this set bypassed the tone controls on the front of the speaker.

[Dylanl]

Here is what mine looked like to start

[Tom Brennan]

Some fella built these outboard 19 crossovers, I forget who, but that's what I'm inclined to do. That way I won't bugger up the stock ones; note that just because something sounds different doesn't always mean it's better. Berenek's Law and all that.

Anyway it would be good to have the stock crossovers and seperate modded crossovers, then one could compare.

To tell you the truth I'm enjoying my "new" 19s so much as they are I'm not too worked up about crossover mods anyway. Not yet anyway. ;-)

[Paul C.]

I'm Paul C. that built GaryL's Model 19 crossovers.

Gary sent some Model 15 stripped chassis that are identical but for marking on the faceplate, as well as some new 8 ohm L-pads and knobs.

I have the Model 19 schematic so, it was time to order parts.

Inductors... I got a Jantzen .33 mH 15 ga aircore to use for the .3 mH, and a .8 mH 18 ga aircore to use for the .77 mH specified in the schematic. These differences in values are so small as to be inaudible.

Since the .33 mH was to be in series with the woofer, the 15 ga was chosen so as to have minimal resistance. The .8 mH (or .77 mH) inductor is a shunt to ground in the HF section, and the resistance is not a real factor in performce.

For large inductors, anything from 1.0 mH on up, I use iron core inductors. They are smaller, use less wire, and have less resistance than the same value in an air core. Plus they are cheaper, only 1/2 or 1/3 as much. The problem of "saturation" of iron core inductors only happens at power levels of hundreds of watts, and even then, only momentarily. At those volume levels "high fidelity" is not a priority, and even then, unlikely to be noticed. Besides, the originals are iron core, or "transformer" type inductors. Iron core is the practical choice here.

Caps used are Dayton polys. For very larger values I usually use electrolytics, but none were needed here. Again, I made a few value substitutions. 8.2 uf was used where the 8.0 uf was specified, and 6.2 uf was used where the 6.0 uf was specified. These are certainly close enough. Also, 4 ohm resistors were used for the specified 3.9 ohm resistors, and "close enough for jazz".

The large iron core 2.7 mH inductor was screwed to the chassis. The two aircore inductors were strapped to the chassis with Ty-Wraps, as well as being stabilized with blobs of glue so they would not vibrate. They were oriented to minimize crosstalk.

The caps and resistors were glued to the chassis and to each other. Hot melt glue is not used, it may damage capacitors and does not stick well to metal. I use a glue I have found to be perfect for this use, E6000 by Eclectic Products. There is a similar glue, a little more solvent so it is thinner, called Aleene's Platinum Bond 7800 that works well, too. These glues can be found in hardware, hobby, and craft stores. I get them at Walmart in crafts. These glues are "SBR adhesives", that is, Styrene Butadyene Rubber adhesive. They dry clear, and are very slightly rubbery. They do not give off acetic acid like some silicones. They are flexible when dry but much firmer than silicone. I keep both E6000 and 7800 in my shop and go through at least a tube a week. Great for gluing dissimilar materials, and sticks well to metal, too.

[Mr. Widget]

I have also listen to this passive pair on a friends set of 19's.

You might suggest that your friend remove that bolt from the core of that inductor... I doubt that is an aluminum bolt and wing nut... if you must run a bolt through the core of an inductor, use brass.

Placing a steel bolt changes the value (increases) and will easily saturate at higher power levels.


Widget

[AltecLansingFan]

Many people say, Altec Lansing model 19 is one of the best sounding models Altec ever made. I'm an Altec fan since 1969, and I listened a lot of different models. I think model 19 is the best model. But also may people say the 811 horn is the best horn for a 1" driver. So my last project (this winter) is to build the most optimal speaker with Altec components as 416-8B speaker, 811 horn (including some gypsum work), 808-8B driver and for some higher frequencies, and some more air in the sound a ESS Heil Air Motion Transformer on top. The sound is what you hear by your ears, and that is very depending on in what kind of room you are listening. I think the room can makes your sound fantastic or bad. I think Altec is a the ideal speaker to play with, I mean a normal Altec speaker enclosure with standard Altec crossover sound very forward. If you want a wide sound wall, like you hear a life band playing, that's what I prefer, you can change/upgrade the crossover and you can accomplish fantastic results.
I used the crossover schematics from Jeff Markwart's model 19, upgraded this crossover with North Creek 10 AWG Music Coils. These coils are really wonderful, and they sound much much better than the Mundorf coils.
Solen caps, witch I (later)upgraded with Hovland bypass caps. Later I want
to try (test) the Vishay o.o1uF bypass caps instead of the Hovland's. But now at this time I'm very happy with the results, the sound of this speakers is remarkable, exceptional detailed and very open. I created a perfect wide sound wall, it is like you hear life music. Now I must finish the enclosures and the job (I think my last speaker job) is finished.