Ideas or concerns about upgrading a pair of 9849A's

[wolfenbit]

Hello,
I am new to the forum, and have obtained a pair of Altec 9849A Studio monitors.
The bass is fine, but I would like to enhance the upper end with 908-8B drivers.
Should the crossovers be rebuilt or redesigned? Do the enclosures need to be ported as in some of Altec's other models? Any thoughts on the pro's and con's of protecting these speakers with fuses? What is with the speaker wire terminals? Hard to believe there was nothing better off the shelf to equip these with in the mid 70's.
I have time off during the holidays to work with these speakers. I am building stands to get them about 18" off the floor, they sounded way too muddled close to the floor. They are currently on stands I built for Wharfedale Diamonds. ( I usually
tend to overengineer things whenever possible).
Thanks for your time, and Happy Holidays to all.

Sorry for the delay, I had to build bookshelves for my daughter for Christmas. The speaker serial#s are 632 and 633. I am going to install the 908-8B drivers but need to verify whether they have loading caps or not. If so, how do you get them out? On the vintage Altec site, the pdf for the 9849A does not show them to be ported as the -8b's were.( That was the reason for my earlier question.) The woofers are definitely 414-b's, but the serial numbers are hard to read. Unsure what the older HF drivers are, the top end rolls off too early for me to believe they could be 902-8T's. ( I haven't a clue really.) The crossovers seem to be in good shape, but I am getting rid of the stock speaker terminals, and am going with a design to accept banana plugs. I took a few more pics which I will upload later.
Thanks for the feedback, you guys rock!!!

[bowtie427ss]

Unsure what the older HF drivers are

Look like 806-8A's to me.

but I am getting rid of the stock speaker terminals, and am going with a design to accept banana plugs.

Stock terminals are easily upgraded and i can think of many reasons to do so.

OTOH, banana plugs were designed for easy interchangeability of test leads on test equipment. I can't think of any good reason to use them for speaker connections. They are unreliable, and inconsistent for long term current transmission. Don't wait until one eventually vibrates out and shorts the speaker lead when you've stepped out of the room. My amplifiers all cringed watching me type this.

One of the best speaker connections you'll ever make is a lightly tinned bare wire firmly clamped down in a binding post. If you need something that looks fancy to impress your friends, use some gold plated spades and dress up their installation with some cable "pants" made from different colored heat shrink.

[Old Guy]

908 is Symbiotik, Altecspeak for an aluminum dome/synthetic surround. Can be identified by a brown ring around the dome.




Image from Bowtie's photobucket


So in order...

Remove loading caps, add felt. You will need shorter screws.

Aluminum GPA frams.

Recap crossovers.

All of the above will improve HF dramatically. The only thing I could suggest beyond that is a crossover similar to the Model 19 with separate mid/high adjustments. It would raise the xover to 1200 Hz but that should not cause an issue.

[bowtie427ss]

The only thing I could suggest beyond that is a crossover similar to the Model 19 with separate mid/high adjustments. It would raise the xover to 1200 Hz but that should not cause an issue.

I agree, a mid adjustment would be sweet, but the stock XO is really a pretty good one albeit a PITA to work on as it's pretty stuffed.

His stock XO's should cross at 1500hz, they even have a bit of EQ built in to help smooth and perceivably extend the HF a bit with those 806's.

[Old Guy]

His stock XO's should cross at 1500hz, they even have a bit of EQ built in to help smooth and perceivably extend the HF a bit with those 806's.

Scratch my last comment then, stocker prolly OK. I have only owned 900 Hz crossover versions, so was thinking of that. Recapping should be done AFTER the other mods. Might not be necessary.

[wolfenbit]

Hello again,
I have written two posts, but have been mysteriously logged out both times before they went through. (Wouldn't be such a big deal if I could type worth a damn.) Anyways, the 9849A crosses over at 800hz, with a top end that extends only to 15khz, per an old Altec brochure. If they had the 902-8t's in them for hf drivers, that would take them out to 20khz, and I would leave them alone. I purchased the 908-8b's for replacements. I have not been able to get them apart to check for loading caps, I don't want to pry on them and damage them.
I understand the concern about the banana plug conversion. I would definitely expect problems if the speakers were connected and disconnected often. I have them on a pair of Wharfdale diamonds, and haven't had any issues. They are also on the Perreaux amp which will eventually be used to drive the Altecs.
If the 908-8b's require a higher crossover point, I will gladly rebuild the crossovers. And the final project will be new cabinets, I have a lot if furniture grade 3/4" plywood I scored for free from work.
It would be a shame if the final product didn't look as good as it sounds.
Thanks for your input, all feedback from the audiophile legends is appreciated.

[bowtie427ss]

Anyways, the 9849A crosses over at 800hz, with a top end that extends only to 15khz, per an old Altec brochure.

I'd double check the component values in your networks. It's possible their evolution took place in steps, possibly the 414 came along before they raised the crossover point. But, i am doubtful of this.

Can you post an internal pic of a network?

The 1975 reference guide(one of the most trusted pieces of Altec lit) says 9849A uses the 32343 network. http://www.lansingheritage.org/image...ers/page11.jpg

The 1500hz 32343/9849 network is fairly unique and fairly easy to recognize with an internal pic, also not a bad idea to inspect for broken solder joints/lugs, i've encountered more than one on this model.

It's been brought to light several times on this forum that the Altec literature is not 100% accurate, and we also have to consider that changes and revisions were ongoing, often after catalogs and brochures were printed.

One of the big advantages of the evolution into the 414 woofer would have been the 414's ability to smoothly play up to a much higher crossover point than the previous woofer in a sealed alignment. So, my logic wants to believe the 414 and 1500hz XO point came along at the same time.

Just my .02 .................

[Altec Best]

Look like 806-8A's to me.

Yup agreed ! Since they are 8 ohm they are 806-8A's 16 ohm would be 806A. The 806-8A's I have seen all had the 23744 diaphragm in them.So they should have plenty of top end.Yes the first places to look are at the diaphragm and inside the crossovers.Also loose grounds/wiring.

I have no doubt when you track down the problem you will be happy with them.They should rock !

FWIW - Those montors look like 9849-8B's


http://altecpro.com/pdfs/vintage/Spe...r%20System.pdf

[bowtie427ss]

Careful AB, his internals are date coded 1974, and use "pipe and plate" alnico motors. 9849-8B uses all ferrite motors, introduced prolly sometime in 1979-80.

AFAIK, the history goes something like this:

9849A originals used a foam edge woofer, sealed box, and 900hz XO.

Sometime not long after their introduction(very early 70's) came the 414 and ports. The move to a 1500hz XO may or may not have happened at the same time.

Sometime late '74 or early '75 the 9849-8A was born with the newly designed cast return pots on both HF and LF sections.

9849-8B arrived circa 1979-80, and with it's new ferrite motors offered a big step up in sensitivity and sizzle at the cost of some midrange smoothness and warmth.

This is my .02 based on the info i've been able to glean over the years combined with owning multiple 9849's, temper it accordingly.

[Altec Best]

Careful AB, his internals are date coded 1974, and use "pipe and plate" alnico motors. 9849-8B uses all ferrite motors, introduced prolly sometime in 1979-80.

Bowtie I'm referring to the enclosures he has there.Although it says 9849A. It looks like a 9849-8B to me,they are ported cabs.

WRT the internals it wouldn't be the first time that Altec speaker systems had other internals than what it was supposed to be ! Where are you seeing date codes on those drivers ?

In the Altec Ling or LTV era is when there was the most discrepancies IMO.The 414 is definitely in the Ling era.