PDA

View Full Version : Anyone want to trade 846B's for POlk SDA's?



avguytx
01-15-2007, 04:26 PM
I know. Odd question. I have a pair of recently acquired 846B's and I'm still not thrilled with them. Anyone have a pair of Polk SDA series speakers they'd want to trade maybe?

That or tell me what it takes to get some highs out of these things. I cleaned the L-Pads, connectors, etc, but they still sound as flat as day old beer. My Polk's, EV's, etc sound better than these do. Sigh...

Help!

spkrman57
01-15-2007, 05:11 PM
1 ufd cap in series with horn tweeter should work well enough.

2404 or 2405 is good place to start with tweeter.

I even find acceptable(16khz top end) results with 075/2402 bullet!

Ron

avguytx
01-16-2007, 03:18 PM
After spending a little more time cleaning and listening, I'm thinking I like these more and more. An "Altec" friend in Arizona recommended changing out the caps since they had been sitting for years. What about the coils, L-Pads, internal wiring, etc? I have no problem building another X-Over board so I can keep the original intact. What about going to some better banana plug connectors? These stock connectors can't take any kind of reasonable size wire without stripping off strands! I'm running 12awg wire...btw.

Thanks for any input!

bowtie427ss
01-16-2007, 03:52 PM
Freshening the crossover is a must. I used to think some of the "magic" was in the factory iron inductors, i've since changed changed my view on this after being show 2 stock inductors that were WAY out of spec.

Sometimes the alnico will lose charge in the HF drivers, weak magnets can reduce HF output.

Clean the HF drivers and the screens in the gaskets, don't omit the screens they have a purpose.

IMO, there are as many gians to be had mechanically with the cabinets as there are electronically. Those cabinets desperately need front/back braces. Additional internal bracing all the way around will do much to clean up and reinforce low end output.

Personally, i'd build new XO's and shift the crossover point up to that of the model 19, 1200hz. That's my personal take on how to really make a valencia perform.

Also, rotate the woofers 180 degrees after verifying that the surround resin hasn't ran and isn't sticking the surround and cone to the baffle, this can create a torn cone surround tragedy during woofer removal.

HipoFutura
01-16-2007, 07:18 PM
I have a pair of Polk SDA's that I don't want. Are you still interested in a trade? Don

avguytx
01-16-2007, 10:29 PM
Which SDA's do you have? You're in Maine? Man, that would be a long trip from Texas! lol But I guess it depends.

HipoFutura
01-17-2007, 04:34 AM
They are SDA 2. They are in nice condition and I do have the interconnect cable. These things are monsters! Would have to do it via UPS. If you're interested we should take this off the forum and use email (dhills at maine.rr.com). Don

avguytx
01-17-2007, 06:38 AM
I'm looking for something larger than the 2's really. I want the SRS, 1.2, 2.3, etc. I would hate to think of shipping these Altecs and the cost it would be...for either speakers, really!

I'm going to replace the crossovers, wiring and L-Pads in the Altecs (while keeping the stock stuff original) and re-evaluate them. I'm getting to where I like the sound more and more and I think it can only improve after the upgrades.

HipoFutura
01-17-2007, 06:50 AM
Cool Beans. These things are taking up way too much storage space! Don

Gary L
01-17-2007, 11:38 AM
Hey AVGUYTX, have you checked to see what HF drivers you have and more importantly what diaphragms are in them?

I agree that the XOs could be suspect here but the first place I would start is at the driver and diaphragm because some fool may have done some switching in there along the way.
You could have the symbiotic or phenolic phrams that require a laoding cap and I have never been happy with the way either of them sound.
Your alnicos could need recharging and especially if they were driven hard or messed with in some other way.

The diaphragm number is on the underside and stenciled on the oposite side of the voice coil windings. It is not the 391XXXX number but the numbers I think sound best are 23744 and the newer 34647. I am sure there are others that sound fine also but I don't know the 806 driver which is probably what you have. I also don't know how to test for magnet strength! One friend replaced his phrams with Radians that work and sound fine and another tried them with terrible results because they did not fit properly. I like the 34647s sold by GPA and if he installs them he also recharges the mags while they are there.

If all is good inside the drivers then you probably do have an XO problem that new caps might solve. From what I have heard here, your caps may be potted in the goo and they can be a job getting to.

Too bad you are not closer because I have drivers and XOs you could switch around to determine where the problem really is. This is the non tech way to do it but switching to known working drivers and XOs works for me.

Gary

avguytx
01-17-2007, 12:26 PM
Hey AVGUYTX, have you checked to see what HF drivers you have and more importantly what diaphragms are in them?

I agree that the XOs could be suspect here but the first place I would start is at the driver and diaphragm because some fool may have done some switching in there along the way.
You could have the symbiotic or phenolic phrams that require a laoding cap and I have never been happy with the way either of them sound.
Your alnicos could need recharging and especially if they were driven hard or messed with in some other way.

The diaphragm number is on the underside and stenciled on the oposite side of the voice coil windings. It is not the 391XXXX number but the numbers I think sound best are 23744 and the newer 34647. I am sure there are others that sound fine also but I don't know the 806 driver which is probably what you have. I also don't know how to test for magnet strength! One friend replaced his phrams with Radians that work and sound fine and another tried them with terrible results because they did not fit properly. I like the 34647s sold by GPA and if he installs them he also recharges the mags while they are there.

If all is good inside the drivers then you probably do have an XO problem that new caps might solve. From what I have heard here, your caps may be potted in the goo and they can be a job getting to.

Too bad you are not closer because I have drivers and XOs you could switch around to determine where the problem really is. This is the non tech way to do it but switching to known working drivers and XOs works for me.

Gary

Gary,

Thanks very much for the reply. That is the most information I've gotten so far. I have the H811B horns with the 806-8A drivers and the 416-8Z woofers inside. I have taken the speakers out to inspect the inside of the cabinet for pics, etc. I don't know which diaphragms are in the 806's, either...haven't taken them apart to check. Is it safe to take them apart to check? There isn't some sort of "magical gasket" that is going to come apart is there? lol I'm not scared of taking them apart to make sure of what's there.

Don't get me wrong. They don't sound "awful" and this is my first ever set of Altecs and my first set of horn speakers since my LaScalas back in the early 80's. I just know in comparison (and from what I've heard) that these and most horns won't have the upper high end that some other speakers will. For instance, my Polk's KILL the Altecs on top end and just overall, sound better at this point. Also, I have an original pair of ElectroVoice Interface C's with the EV T350a "baby cheeks" horn and they sound better as well. I haven't even touched those speakers since the drivers are a biotch to get out of the cabinets. They are bone stock and are about the same age give or take a few years.

Someone even mentioned that the wires to the horns might even be backwards (reversed), I just hooked them back up the same way they were when I took them out. I made notes...

I can take some pics if need be of anything if it would help out in your diagnosis. Believe me...I do appreciate your help! I do have a couple of the internals of which I'll attach here.

Thanks again! Kip

Gary L
01-17-2007, 01:34 PM
No magic gaskets but you do have to be carefull of two things. If the magnets are strong be aware they could pull your screw driver in to the diaphragm dome--- NOT COOL!

I always mark the diaphragm position and wire colors with tape so it goes back exactly as it comes out.

Very carefully with an xacto flat blade I slip it under the diaphragm and the face plate and slowly loosen it up all the way around until all is free.
Carefully lift the phram straight out.
It should look like this except your phase plug will be metal and not orange. Numbers are under the dome and on the VC part that goes in the gap.
http://img.photobucket.com/albums/v722/Gamalot/HF%20Drivers/32_1.jpg
Inspect the leads from the attacment points to where they go into the dome.
A kind of non technical test after the fram is removed and away is to check how strong the magnet pulls with the wrench you use to remove the driver nuts. Strong magnets will hold quite tight while weak ones will just pull a bit. About all this is good for is to see if both drivers seem to have similar strength.
Gunk, rust or any crud in the gap is not good and sometimes masking tape doubled over backwards with sticky side out can be slid in to grab debris out. I would not use any liquid sprays in it.

Looks like your XOs are simple to recap! PE probably has what you need for cheap. You can get real crazy with caps but the Daytons at Parts Express work just fine IMO.

Hope this helps but do be carefull. I think you must have a problem somewhere because your speakers should be every bit as nice or nicer then the others you mention.

Gary

Storm
01-17-2007, 01:42 PM
Gary -

I would like to update my x-overs also.

From the picture above - where are the "caps"? Which ones should I order from Parts Express?

How do I take the other ones off and replace them? Do I need a soldering iron?

Anything else I need to update while I am in there?

Thanks.

-Storm.

Gary L
01-17-2007, 01:58 PM
The two black cylindrical things are the caps and they have red/maroon tops and bottoms.
You will need a soldering iron and you need the numbers from the old ones that are probably like 3 uf or 8 uf.

If you can get a pic posted showing the numbers PaulC can usually cross them and give you the PE number to order.

Buy a can of Caig D-5 Deoxit from PE when you order and spray it into the L-pads and work them back and forth a bunch of times, do it again 15 minutes later. That usually cleans them up or you could just buy new ones.
I have never had any other parts go bad so far so I don't fix it if it aint broke.

Gary

Paul C.
01-17-2007, 02:56 PM
Looking at the photo, your crossover is a "2nd Order" aka 12 db/octave crossover. Here is a schematic:

http://ccs.exl.info/calc_cr.html#second

http://ccs.exl.info/images/calc_cr_12db.gif

Except yours has an L-pad inserted between the crossover and horn driver.

The capacitors are as shown here:

http://i15.photobucket.com/albums/a384/PaulCoats/StormsXover.jpg

They are held by small clips. The Dayton or Solen caps you will buy from Parts Express will be larger and not likely to fit those clips. I would carefully sketch the wiring, and repair only one crossover at a time, using the other as a reference.

I don't know the coil values (those little transformer looking things at the top of the photo), but if I knew the capacitor values and the published crossover frequency, I could give a good guess.

Since you will have to remove the clips, you will need to glue the new caps in place. I use a craft glue called E6000 or similar Aleene's 7800. This was mentioned in the thread about the Model 19 crossovers. Walmart craft department or craft and hobby shops.

Be careful, the old wiring may be brittle and it is easy to break a wire when moving them around.

If after cleaning the L-pads are still noisy, I would simply replace them. But if they are not noisy, that is, when playing music and adjusting the L-pad there is no noise produced, then leave them alone. That is an 8 ohm 100 w L-pad with 3/8" shaft.

Gary L
01-17-2007, 03:13 PM
Thanks Paul! I do very little of my own electronics as you are well aware.

Those are pretty simple XOs IMO but I still have to ask this question.

Heat sink? I always use a pair of needlenose pliars with a rubberband as a clamp between the cap body and solder point to keep heat from getting to the cap. I suppose it is more important the shorter the lead is but is this a good precaution when soldering in new caps?

Gary

avguytx
01-17-2007, 03:17 PM
Paul...you are always such a great help! The crossover point for these speakers is 800hz. Hi and Lo pass. Yes, even after cleaning, there are areas on the Pad where it's not making contact and they will cut in and out.

What I'm going to end up doing on the crossovers is to rebuild a new board to hold them and the L-Pads both and then attach it in the stock location. This saves me from altering the original one and easier use for reference. Also, that lets me put some female banana plugs on there so I can put REAL wire into them instead of having to strip it down in order for it to fit in that 20awg opening! I'll also seal it off with a foam tape or something. Considering the stock panel took nothing for it to come off, it HAS to be better!

I'll get the crossovers out tonight and check the actual ratings on them and let you know. I think I have a couple of programs on my laptop for coming up with the values, too, so we can cross reference!

Storm....this will work out well for the both of us! I have all the goodies to build the X-overs. Soldering irons, etc. I'd be glad to help out if I can.

Thanks again!

Storm
01-17-2007, 03:37 PM
Av - that would be much appreciated.

Can you build me a pair? I will compensate you.

Like you, I would rather have another set - that way, not to mess with the originals.

Thanks!

-Storm.

Gary L
01-17-2007, 03:41 PM
Sounds like a bit of that "Southern Hospitality" to me.

Have fun guys and post some updates on the results.

Gary

Zilch
01-17-2007, 03:47 PM
Heat sink? I always use a pair of needlenose pliars with a rubberband as a clamp between the cap body and solder point to keep heat from getting to the cap. I suppose it is more important the shorter the lead is but is this a good precaution when soldering in new caps?Alligator clip....

Gary L
01-17-2007, 03:53 PM
That makes it easier! Thanks Zilch.

Gary

Storm
01-22-2007, 10:30 AM
Just saw the eBay auction.

You are selling the 846Bs?

What is the reserve?

Why did you end up selling them?

Thanks.

-Storm.

http://cgi.ebay.com/Altec-Lansing-Valencia-846B-Vintage-VOTT_W0QQitemZ190075208678QQihZ009QQcategoryZ14993 QQrdZ1QQcmdZViewItem

avguytx
01-22-2007, 09:18 PM
A couple of reasons. Just don't have the physical space to do them justice and don't want to have to buy certain equipment just to make them sound better. Don't get me wrong...I like them but they just aren't the sound I like. I have a wish list of speakers I want to have at least once and that was one of them. I still like my Polk's and EV's better.

I don't want to say what the reserve is as I want the auction to run it's course. They are gorgeous speakers...that's for sure.