9846 and 9849 projects

[RonSSNova]

The 9849-8B first up because all I have to do is install the drivers.
Yes, the woofer baskets are white, they started life as 417-8H drivers. I had them reconed as 414's years ago.
Used them in some quick and dirty boxes for my son. Got them back because they were too big and fugly for his new home. I put the vented dust caps in last week because the recone guy used non-vented caps. They actually have real Altec cones in them as far as I can tell.

These had the rare 806 style HF drivers with tangerine phase plugs and the lightweight diaphragms. Those drivers are now in my Model 19's. So, these are getting the 902-8A from the 19's.

Original crossovers are in place. I'd kind of like to try some Model 19 crossovers as I have a pair in stock.
The horns are plastic. One has an aluminum brace on it.

Cabinets are a little rough, one was hung from a ceiling. The other has a spatter finish. I figured I'd listen to them for a while then figure out how to paint them. If you have any suggestions there, fire away.

The 9846's are completely disassembled. Cabinets got a little water on them here and there from a slight basement leak. Swells up that particle board quite well. They will also need paint. And Bondo.

I'm missing one N501-8A crossover. And the woofers need cones. From the "aftermarket cone" thread, I mentioned that I bought recone kits. The more I look at those, nothing is like the original parts, and when done the driver won't perform like intended. Not to mention, the cone does not fit over the voice coil, at all. I test fit the parts. Going to be a $200 mistake. It won't be my first.......

Onward and upward!

Ron

 

[bowtie427ss]

Cabinets got a little water on them here and there from a slight basement leak. Swells up that particle board quite well.

Particle board, really?

Those were early models with the doped cloth surround?

The more I look at those, nothing is like the original parts, and when done the driver won't perform like intended.

I wouldn't sweat it. They surely wouldn't be the first cone kit i've seen that needed to be trimmed to fit, get them installed and broken in. If some basic analysis shows them to test close to each other, you've cleared the biggest hurdle. IMO, it's more important that they both perform equally.

Honestly, i'm not convinced that any 411 performs as originally intended since they stopped using the cloth surround.

 

[mvandyke]

Looking forward to some updates on your project Ron. Keep up the good work!

 

[RonSSNova]

Particle board, really?

Those were early models with the doped cloth surround?

I wouldn't sweat it. They surely wouldn't be the first cone kit i've seen that needed to be trimmed to fit, get them installed and broken in. If some basic analysis shows them to test close to each other, you've cleared the biggest hurdle. IMO, it's more important that they both perform equally.

Honestly, i'm not convinced that any 411 performs as originally intended since they stopped using the cloth surround.

Yep, particle board. When I bought them, they had carpet glued to the tops.....shag even!
I seem to remember the woofs having nonstock cones and were rubbing. It was a long time ago.
I sent the cone folks an email with some questions, they got back right away and said they would have answers for me soon. That was last week.
And you are correct about the foam surrounds changing the parameters. I measured that way back when GPA did my other set. No doubt Altec knew that, but never updated the specs. Those cloth roll surrounds were very weird....they just guided the cone.

 

[RonSSNova]

Looking forward to some updates on your project Ron. Keep up the good work!

Thanks Matt. the 9849's are assembled. I'll need help moving the 904's off the sub cabinets. Double layer MDF, they are too heavy for my old back.
The 9846's will be a slow motion project.

 

[RonSSNova]

Here are a couple photos of the cones sitting on a 4.00" thick Aluminum tube.
And yes it's a GM mass airflow Sensor tube.

Perhaps a reconer guy could tell me how to fit these.
I checked the voice coils and they are right on at 4.0"
I was thinking maybe wet the cones and form them over the alum tube?
The supplier has not responded with answers to my questions.

 

[bowtie427ss]

A snug fit is OK.

The problem is that if it's too snug, it can deform the cone, coil former, or both.

The kind of thing the seasoned speaker tech will know by feel.

 

[RonSSNova]

It's way more than snug Tom. It won't go over the VC at all.
If I force it over the 4" tube there, my guess is it will tear the cone.
Simply Speakers still hasn't responded to my question on this.

 

[RonSSNova]

Ok, still no reply from SS. So car guy skills to the rescue.
These cones are pretty robust. So sand paper it was. Carefully sanded the cone so it just slid over my 4" tube I showed above. Still had to go a bit further to fit the voice coil as it has the leads coming out the side, which makes it even larger than 4". Altec runs the leads inside the coil form where there is a small gap.
Now it all fits together. Just a light snug fit. The photos below are just a test assembly.

 

[RonSSNova]

Couple more photos.
Their shims, they gave me two, are .005" thick. Two won't go in, so I found a stiff mailing envelope that is .004" thick.
Adding this keeps the VC solid enough that it doesn't move when installing the spider or the cone. Tells me the gap is .0095".
These are overhung voice coils. I had to look that up. Part of the coil is above the magnetic gap.
I am assuming I need to get as much of the coil as I can in the gap while still being able to glue the spider and the cone to the VC.
Correct me if I'm wrong.

I have both cones fit now. That takes an hour or so per cone sneaking up on the fit.

 

[bowtie427ss]

I am assuming I need to get as much of the coil as I can in the gap while still being able to glue the spider and the cone to the VC.

There's a proper spec for this, somewhere. In absence of that, what you generally do is measure the old assembly as it's coming apart, and match that. I fear that's not much help at this point.

These are overhung voice coils. I had to look that up. Part of the coil is above the magnetic gap.

The idea being that voice coil will remain in the magnetic sweet spot across the majority of the cone's large excursion allowing performance to remain more linear(larger Xmax).

I am assuming I need to get as much of the coil as I can in the gap while still being able to glue the spider and the cone to the VC.

Ideally, there is a center point(home position). I don't know how to determine this without service data, or measuring the old assembly.

If the coil is too deep in the gap, there's a danger of the coil/former crashing the back of the gap on large excursions.

If the coil/former is too far forward, there's a danger of it leaving the gap and getting hung up on the pole piece when it tries to return to home position.

At this point i would probably reach out to a guru like GordonW, or your local speaker tech.

If it's any consolation, so far, you've done what i would do.

 

[RonSSNova]

Thanks Bowtie, was hoping you might chime in.
I measured the cone movement on my GPA reconed 411s'. Pushing the cone in to where it just wasn't going any further, it moves .375". So, let's say it could go .400".
I didn't want to push it further.
Where I'm at now with the current coil position is .640" from the bottom of the gap. I think I'm ok there. Total gap depth is 1.21".

I captured a couple of stills from the video of the guy who repaired 411's on YouTube. See below. Revealed a lot as he measured the OEM winding length. Easy to scale from a print when one measurement is known. The length of the coil stock is .670". These are .875".
Also showed me the correct orientation of the neck on the spider. I currently have it upside down.
I am assuming both the Altec coil form and the aftermarket form are both 1.50". Kind of dictated by the mechanics of this.

I also read through The Speaker Exchange install instructions. much more detailed than the Simply Speakers booklet. They actually talk about how to cut the cone when it's too small for the VC.

I could be close to cracking open the glue.

 

[RonSSNova]

Got one 90% done. All glued up. Need to wire it, dust cap and gaskets. No voice coil rubs!

Anyone know where to get the binding posts? The solder lugs which are unique both broke off.

 

[bowtie427ss]

If the spacing isn't right on the Parts Express unit, the ones from The Lord of Bass omit the mounting strip and mount right to the frame.

https://www.parts-express.com/Spring-Loaded-Speaker-Terminal-Nickel-13-16-Tab-091-1142?quantity=1

https://thelordofbass.com/product/spring-loaded-binding-post-speaker-terminal/

 

[RonSSNova]

Ah thank you. Not sure I can afford those….

I really like the old thumb screw type Altec used. Those were nice.

 

[bowtie427ss]

I really like the old thumb screw type Altec used. Those were nice.

Those are available. 30 bux/pair on ebay.

But, vibration, and warm/cool cycles loosen them.

A spring clip type keeps constant pressure on the contact area, and is advantageous in a location where you cannot regularly inspect them(woofer frame).

 

[RonSSNova]

Got one done. Sitting on the bench wiggling at 20hz.
This is now much stiffer than the orig cone and suspension. Pretty easy to tell as I have the other pair in my subs.
As I push the cone out to its extreme, the surround limits. Flattens out. I'm sure the spider effects this as well.
Same thing when you push the cone all the way in.

I set it on a small step stool and did a quick check of Fs. The null in the series 20 ohm resistor happens at 34.75 Hz.
Let's see, the original cloth surround was 17 Hz, the GPA measured 24 Hz, and these are 34.75 Hz. I'm going to let it sit there and exercise for the rest of the day, my guess is Fs will not change.
Inward travel is 0.25", same for outward travel. I quit pushing at 0.375" on my GPA coned ones.

 

[RonSSNova]

A photo for Bowtie

The 9849's sound very nice. Vocals are sweet. It's rather uncanny, even though too close together, listening, you would swear the sound is coming from the area where the Duplexes are sitting.

See if you see the difference in the two 9849 cabinets.

 

[bowtie427ss]

See if you see the difference in the two 9849 cabinets.

Color?

If that's what you mean, the one on the left is factory, has a good bit of blue in the mix(and your camera rendered it well). Even though their paint suppliers and formulas changed with the wind direction, they(Altec) seem to have always went with a gray that has a lot of blue content.

 

[bowtie427ss]

I'm going to let it sit there and exercise for the rest of the day, my guess is Fs will not change.

Inquiring minds need to know...

I wish i had talked you into getting 1 LE-15 kit, just for kicks and giggles. It seems like 25hz would be a satisfactory compromise if the parts will fit and align.