Altec Model 15 crossover rebuild questions

[rgwalker]

DO NOT replace the original solid core inductors with newer air core inductors. Those original inductors should be fine and air core inductors will have a totally different sound to them--I know of Model 19 owners who replaced their original solid core inductors with new air core inductors and HATED the sound. They then put the solid core inductors back into the crossovers and the "magic was back"! Just my 2 cents......

I've used large air core inductors on three Model 19s and one 604E system with excellent results and would like to credit them with the vast improvement in the sound.

[voice of theatr]

I've used large air core inductors on three Model 19s and one 604E system with excellent results and would like to credit them with the vast improvement in the sound.

Everyone has their own preferences--you're the first person I've heard from that switched to air core inductors in their Model 19 crossovers and actually liked the way they sounded. Of course, that doesn't mean you're wrong! BTW, did you do any measurements after switching to the air core inductors to see how it affected the frequency response?

[rgwalker]

Everyone has their own preferences--you're the first person I've heard from that switched to air core inductors in their Model 19 crossovers and actually liked the way they sounded. Of course, that doesn't mean you're wrong! BTW, did you do any measurements after switching to the air core inductors to see how it affected the frequency response?

It's all subjective and the original designers were very smart people. However, IMHO Model 19s are quite harsh and well suited to loud rock & roll with big amps in large rooms. I called them my Led Zeppelin speakers and it scared the cats who otherwise aren't afraid of loud music. The guy that I bought them from was going to put handles and wheels on them and use them as PA speakers for his band. I wanted to keep them and I tried to like them as an all purpose speaker and even used McIntosh tube amps and preamps but my stock Altec 620As with 604-8Gs and 846A Valencias walked all over them for any near field listening and especially playing music at 2:00 AM volume.

I was given the idea by someone here who saw that I wasn't completely happy and he offered the crossover upgrade as a suggestion that he had found successful. He has done a lot of testing with different products and was sold on North Creek air coils.

Perhaps I should point out that mine isn't an apples to apples M19 conversion. It started out with the M19 but by the time that I got around to it I sold them and built a hybrid using the M19 as a model with 620A cabinets. It's a 3 way with Heil ES tweeters, Altec 311-60 horns and Altec 288 drivers sitting on top and only uses the 416-8Bs and the crossovers from the M19s. However, I did run them with the stock M19 crossovers as a two way before changing out the caps and coils (using stock values) and adding the tweeter. It wasn't a subtle difference and the soundstage became much more apparent (for lack of better words) and almost 3D like and it made listening to all music much more enjoyable with absolutley no fatigue regardless of high volume. Every so often I hear things and I'll get doubts but I'll put on a few recordings that I use as benchmarks and all of my original opinions and feelings are affirmed.

I'm good with a soldering iron and can follow a chart to make things but I'm not technically well versed so I can't give you specs or comment on response and frequency etc and my room is difficult but after 3 years I still really enjoy the system. My opinion is purely subjective and I won't claim that using the big coils is technically better but it certainly isn't a failure and I'll never consider switching back to stock.

I've also used the North Creek coils on a pair of Jeff Markwart 604E crossovers and I love the result.

[voice of theatr]

It's all subjective and the original designers were very smart people. However, IMHO Model 19s are quite harsh and well suited to loud rock & roll with big amps in large rooms. I called them my Led Zeppelin speakers......

I'm wondering if there was something wrong with the drivers and/or h.f. diaphragms in your Model 19's. I own two mint pair and both pair sound considerably better to me than my 846 A Valencias ever did or my Heathkit AS 101's (same drivers as 846B). They put out 100 db with one watt of input power so I couldn't disagree more with your statement that they're suited to big amps and large rooms. In fact, a big amp can be very bad for them/very dangerous for them. Yes, they can fill a large room, but I have one pair in a relatively small room and don't usually put more than a watt through them and they sound great--even at very low volumes. They sound great with all styles of music, not just Led Zappelin--strings, piano, classical guitar recordings, brass, full orchestra recordings sound amazing on mine. There is a ground modification that needs to be done on all Model 19 crossovers now that they're 30 + years old for optimum sound performance--the ground lugs in the crossovers aren't connected to each other/grounded via solder connection--they are connected by a mechanical (rivet) connection which with age is not a good connection. After I recapped my Model 19's with the Solens, cleaned the pots/L Pads, corrected the inadequate ground connections, they had clearer highs, mids, and more bass than ever (the Solens did not make them more harsh or give them less bass). If I had to make a guess, I'd say from your description you either had the later version of the Model 19's that didn't come with the light diaphragms that the early ones did, or someone replaced your hf diaphragms with replacement Altec (or non Altec) diaphragms. The light diaphragms that the early Model 19's came with had a really different character to them than the Altec diaphragms that replaced them--they had a very open and airy sound which from your description your 19's didn't have.......

Another possible explanation comes from this quote

The guy that I bought them from was going to put handles and wheels on them and use them as PA speakers for his band.

He may have blasted those things so loud (if he wanted to use 19's for PA he didn't understand how they should be treated) that the drivers weren't in optimal condition and didn't sound good at low volumes any more (or at any volume)....

Perhaps I should point out that mine isn't an apples to apples M19 conversion. It started out with the M19 but by the time that I got around to it I sold them and built a hybrid using the M19 as a model with 620A cabinets. It's a 3 way with Heil ES tweeters, Altec 311-60 horns and Altec 288 drivers sitting on top and only uses the 416-8Bs and the crossovers from the M19s. However, I did run them with the stock M19 crossovers as a two way before changing out the caps and coils (using stock values) and adding the tweeter. It wasn't a subtle difference and the soundstage became much more apparent (for lack of better words) and almost 3D like and it made listening to all music much more enjoyable with absolutley no fatigue regardless of high volume. Every so often I hear things and I'll get doubts but I'll put on a few recordings that I use as benchmarks and all of my original opinions and feelings are affirmed.

I'm glad you mentioned this--it explains a lot. The Model 19 crossover is different than the older Altec crossovers (even ones from a year or two before the 19 was introduced). For one, it has very specific EQ compensation specifially designed for use with the 802-8G/811B horn combo. If you used them with 288 drivers and 311-60 horns you had the wrong drivers and horns for that crossover design. It's no wonder you needed to do crossover mods and add a tweeter etc.--the 288 doesn't have anywhere near the upper frequency extension that the 802-8G (tangerine phase plug) has......

Bottom line, I'm glad the new inductors allowed your crossovers to sound good with your system--288's, 311-60's, tweeter, etc.--that's all that really matters--your system now sounds great! As you mentioned, it's an apples and oranges comparison because your modified crossovers will sound really different used in Model 19's than they will with your (totally different) h.f. driver, horn, and tweeter combination.

By the way, I agree--always save the old caps. If they are still at their original values, they will have a different character than other types of caps and you may prefer them--it's always possible. Also, if you sell your Model 15's some day, it's nice to let the buyer know that even though you upgraded the caps, you'll be including the originals as well so he'll have all the original stock parts--even the original caps......

[mjcmt]

In my experience, those old non-polar caps sound very good, and you may just find that the speakers don't sound as good with the new and "improved" caps as they did before.

I planned on keeping them, mostly to have available if I ever sell these speakers.
I do have one question, are the new Solen caps I've ordered directional? If so what must I be aware of?

[rgwalker]

I'm wondering if there was something wrong with the drivers and/or h.f. diaphragms in your Model 19's. .

They were fine. I've been around other Model 19s and these sounded the same. I'm not trying to turn this into a complaint about Model 19s and I apologize if it looks that way. My original point is simply that using air coils was a good thing for me and therefore not a black & white dismissable issue.

[mjcmt]

Looks like this thread has been hijacked from my Model 15 x-over rebuild to Model 19, Altec drivers and the like. Though somewhat interesting, I keep looking for replies to my post only to have to read through other replies to find appropriate answers.

[Salectric]

Voice of Theater's post #19 made a good point about the eq circuitry in the 19. The M15 also has some high freq eq to compensate for the rolloff of the 802-8G and (perhaps) in the 32B horn. When I tried a pair of M15 xovers, I found the eq to be helpful but not entirely satisfactory. I later got a pair of 9849 xovers which were also designed for the 802-8G and 32B horn, and the eq circuit in that xover is really good. My 802s no longer sound rolled off on the very top; they are fully extended to my ears. If you're interested in trying the 9849 circuit, send me an email and I'll send a schematic.

[voice of theatr]

Looks like this thread has been hijacked from my Model 15 x-over rebuild to Model 19, Altec drivers and the like. Though somewhat interesting, I keep looking for replies to my post only to have to read through other replies to find appropriate answers.

Guilty as charged! Sorry about that. Your thread did get sidetracked--went off on a tangent that began with your Model 15 inductors and then went into inductor/Model 19 discussion. When someone says Model 19's are suited for big powerful amplifiers etc., I can't reach for my keyboard quick enough...... A thousand pardons, please!

I planned on keeping them, mostly to have available if I ever sell these speakers.
I do have one question, are the new Solen caps I've ordered directional? If so what must I be aware of?

OK, back to your thread! The Solen fast caps are NOT directional. No need to worry about orientation/which end of the capacitor to hook up where......

Voice of Theater's post #19 made a good point about the eq circuitry in the 19. The M15 also has some high freq eq to compensate for the rolloff of the 802-8G and (perhaps) in the 32B horn. When I tried a pair of M15 xovers, I found the eq to be helpful but not entirely satisfactory. I later got a pair of 9849 xovers which were also designed for the 802-8G and 32B horn, and the eq circuit in that xover is really good. My 802s no longer sound rolled off on the very top; they are fully extended to my ears. If you're interested in trying the 9849 circuit, send me an email and I'll send a schematic.

Thanks, Yes I make a good point once in a while! That time frame (introduction of the MODEL 15 and 19) was a turning point with the Altec crossovers. The high freq eq compensation was excellent in those and many Altec crossovers that followed (like the Model 14 crossover--I own a pair of those as well) and really did help the h.f. extension of the h.f. driver/horn combination.

[DavidF]

Looks like this thread has been hijacked from my Model 15 x-over rebuild to Model 19, Altec drivers and the like. Though somewhat interesting, I keep looking for replies to my post only to have to read through other replies to find appropriate answers.

A lesson perhaps. Sometimes it all starts with "maybe I'll just upgrade the caps".

I would recommend some contact cleaner treatment on the L Pads for the mid and highs. Those are good source of grunge collection over time. Squirt some cleaner in cases and give them several lock-to-lock spins. Easier to get to them with them on the bench.

[Earl K]

Voice of Theater's post #19 made a good point about the eq circuitry in the 19. The M15 also has some high freq eq to compensate for the rolloff of the 802-8G and (perhaps) in the 32B horn. When I tried a pair of M15 xovers, I found the eq to be helpful but not entirely satisfactory. I later got a pair of 9849 xovers which were also designed for the 802-8G and 32B horn, and the eq circuit in that xover is really good. My 802s no longer sound rolled off on the very top; they are fully extended to my ears. If you're interested in trying the 9849 circuit, send me an email and I'll send a schematic.

How about simply posting your 9849 schematic here ? ( I'd like to compare it to one { from Corona Blue } that was derived this last spring with some "guessed at" inductor values ) .

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[Salectric]

I'll try posting the 9849 schematic tonight.

[Salectric]

The 9849 schematic is below. The caps are all non-polar electrolytics, and the resistors are 10w or 15w sand resistors. The chokes are all iron-core except for the 0.1mH. The chokes are not marked except with an Altec part number, but I measured them with an inductance meter.

[jcrobso]

The 9849 schematic is below. The caps are all non-polar electrolytics, and the resistors are 10w or 15w sand resistors. The chokes are all iron-core except for the 0.1mH. The chokes are not marked except with an Altec part number, but I measured them with an inductance meter.

The electrolytic caps will go bad over time and should he replaced. If the L pad is "scratchy" or has bad spots replace it. The inductors are fine. the resistors should be OK as they are wire wound.

[mjcmt]

I received the caps from Madisound yesterday, Friday.

Broke down the speakers the same day. While they were broke down I did an inspection of the drivers and cleaned the bit of 35 yr. old debris that had collected on the screen protecting the compression drivers. Everything looks as new. (Woofers were re-coned by GPA in '91.)

Today, Saturday, I rebuilt the x-overs. Installed new Solen caps, hot glues the caps and resistors down, cleaned the pots with contact cleaner, and rewired everything using Audioquest 14 gauge (long-grain high-purity) copper wire.

I also replaced the speaker wire binding posts on the existing Altec cups with robust gold-plated brass binding posts.

While everything is apart, next week I will refinish the cabinets before I put it all together. I will keep you posted.

Here are before and after photos of the crossover.