SDA 1 Signature Upgrade

chuckeroo

Hello!
I previously hijacked the end of this thread, starting with post #7:
http://www.polkaudio.com/forums/showthread.php?150769-SDA-1A-Xover-caps

With some help from Schurkey, westmassguy, and Newbie308, I feel confident enough to go after taking
my SDA 1 signatures apart. I have all of my parts together, and plan on doing the following:

1) Upgrading my tweeters to RD0-194. I already have these in place, but the old hole are very tight against the magnets, so I plan on routing out a bit of the cabinet to accomodate.

2) I bought hurricane nuts and bolts from parts express, so I plan to redrill everything (radiator, drivers and tweeters) and install these

3) Install dampening material to all drivers and radiators

4) Install new binding posts

5) Recap and replace resistors for all 4 crossovers. I have Sonicaps and Mills in hand for all except the large low frequency caps (27 uf) which I opted for Solens to save some money.

I will try to take pics of everything along the way to help any new guys like myself who want to try this in the future, and will post any questions I have along the way here.

To get started, I do have a few questions that are kind of sitting on my mind:

1) I have only ever soldered through hole pcbs that already have a bit of solder on the hole, but I've noticed from pictures that these crossovers are pretty much soldered straight to the copper on the bottom of the board. Are there any tricks to a good joint on these? Do you use some flux or anything to get it to flow/stick easier?

2) I have read before about doing a slow charge on caps before installing them in a system, by somehow using a lightbulb and battery circuit. Something about not filling them up and possibly blowing them? Does anyone do this and is this necessary in this application?

3) I have a multimeter, are there any checks I should be doing before/after installation to ensure my joints are in good working order?


Thanks for any assistance!

Chuck

zane77

Just make sure you heat the joint to be soldered well the solder should "flow" if it is hot enough. Practice on a few pieces before you start. Go and find some broken piece of electronics equipment with a printed circuit board and preactice. Find a broken piece of junk at Goodwill that they are throwing away. The solder should have the flux in the core of the solder, just make surre you are using solder for electronics not solder used for plumbing. You can get it at Lowes, Home Depot, Radio Shack etc. Take a little time and practice and get the feel for it. Once you do it is pretty easy

Schurkey

chuckeroo wrote: »

1) I have only ever soldered through hole pcbs that already have a bit of solder on the hole, but I've noticed from pictures that these crossovers are pretty much soldered straight to the copper on the bottom of the board. Are there any tricks to a good joint on these? Do you use some flux or anything to get it to flow/stick easier?

zane77 wrote: »

The solder should have the flux in the core of the solder, just make surre you are using solder for electronics not solder used for plumbing.

Rosin-core solder, NOT acid-core. I prefer solder with some amount of silver content. (Silver solder) Others will recommend "eutectic" solder, which I have never used, and have no plans to since hardware-store silver solder seems perfectly adequate to me.

chuckeroo wrote: »

2) I have read before about doing a slow charge on caps before installing them in a system, by somehow using a lightbulb and battery circuit. Something about not filling them up and possibly blowing them? Does anyone do this and is this necessary in this application?

Power supply caps will get a 110-to-220 volt "jolt" when the equipment is first fired-up. Speaker crossover caps wouldn't get 10 volts unless you have the volume knob turned up, and in almost any application, there wouldn't be more than 80 volts even with a high-powered amp running hard enough to make it's tongue hang out.

The real problem with caps and voltage has to do with aged capacitors that haven't been used for a long, long time. Fresh caps--unless they've been sitting on a shelf for a year or two--aren't so susceptible to this kind of failure.

chuckeroo

Ok, so this upgrade is just about complete, and went way better than I thought. I can't believe I was so worried about the crossover soldering, it was not only not that tough, I actually thought it was the most fun part of the whole process and was a little sad when I was finished because I wanted to keep soldering! I took lots of pictures and will upload them to this thread with full descriptions and things to watch out for soon. Thanks again to everyone for their guidance!

I have a question regarding one of my drivers though...

Of my 8 drivers, 7 are mw6600x, and one is mw6501. I am going to assume the speakers came with the 6600's which is wierd as the schematics for all the early sda's say they have 6501's, but what can you do. Question is, is that one 6501 significantly different, and should I be on the lookout to match another 6600x? Anyone ever ran into this? Would Polk have just thrown in 1 different driver if it was essentially the same, or would this probably be a case of an owner along the line swapping it out?

Edit: The 6501 manufacture date is 1987, so it's def a replacement. All the 6600x are from 1983.

Thanks!

drumminman

chuckeroo wrote: »

I have a question regarding one of my drivers though...

Of my 8 drivers, 7 are mw6600x, and one is mw6501. I am going to assume the speakers came with the 6600's which is wierd as the schematics for all the early sda's say they have 6501's, but what can you do. Question is, is that one 6501 significantly different, and should I be on the lookout to match another 6600x? Anyone ever ran into this? Would Polk have just thrown in 1 different driver if it was essentially the same, or would this probably be a case of an owner along the line swapping it out?

Edit: The 6501 manufacture date is 1987, so it's def a replacement. All the 6600x are from 1983.

Thanks!

Looking at the schematics and wiring diagrams for the various iterations of SDA 1's, none are supposed to have the MS6600x's. If yours are 1A's they should have all 6501's. Can't find specs comparing the 6600's to the 6501's so can't help you there.

The good news is Polk has replacements for the 6501's.

chuckeroo

So I found a thread here that says that Newbie308 also had 6600x's in his SDA1 Signatures, here:
http://www.polkaudio.com/forums/archive/index.php/t-106062.html

I also found another thread, in which F1Nut says that 6600x and 6501 are interchangeable, so I feel pretty good about it now.
http://www.polkaudio.com/forums/archive/index.php/t-33679.html

So far, the upgraded speakers sound pretty good, but I thought they sounded pretty good before, and I'm not noticing a huge difference. I have read that the new caps will take a few hundred hours to really sound good, so I will leave the stereo on when I'm at work for a while to try to burn them in.

Thanks again!

pitdogg2

drumminman wrote: »

Looking at the schematics and wiring diagrams for the various iterations of SDA 1's, none are supposed to have the MS6600x's. If yours are 1A's they should have all 6501's. Can't find specs comparing the 6600's to the 6501's so can't help you there.

The good news is Polk has replacements for the 6501's.

this is WRONG^^^^^^ you have the correct drivers All should be mw6600 EXCEPT the dimensional which should be MW6501
I also have the SDA1 signature which has the same drivers from the factory. You should find another MW6501 for the other dimensional driver.

drumminman

pitdogg2 wrote: »

this is WRONG^^^^^^ you have the correct drivers All should be mw6600 EXCEPT the deminensional which should be MW6501

Like I said, the above info was from the schematics posted in the vintage forum. Dorokuasi also posted a list of the correct drivers for each model of SDA, and none of the iterations of the 1's were spec'd with 6600's.

If F1nut says that the 6501's are interchangeable with the 6501's you can bank on it.

pitdogg2

geppy1 wrote: »

geppy1

08-29-2010, 02:30 PM

The 6600s were developed of the RTA 12B and used in early SDAs I had a pair of 1983 SDA1s and they had 6600s in them I even mentioned it to DK You have to be careful about going by Polks parts lists. For example they show all RTA12 and 12Bs with 6500s and 12Cs with 6600 and 6500 Yet every single 12B I have had has 6600s and MP response to a review of the 12B by Off the Record talks about the new 6600X driver being developed for the 12B. It is even mentiond in 1982 Lit. Point being he has the right drivers but the later ones could have come with 6501s. I prefer the 6600 in the 12s as i have compared them both but never did it in the SDA Keith. RTA 12 6500s RTA 12Bs 6600 and early RTA 12Cs 6600s late Cs 6501's.

Keith did A LOT OF RESEARCH on these drivers and he is 100% correct about Polk's list.

pitdogg2

drumminman wrote: »

Like I said, the above info was from the schematics posted in the vintage forum. Dorokuasi also posted a list of the correct drivers for each model of SDA, and none of the iterations of the 1's were spec'd with 6600's.

If F1nut says that the 6501's are interchangeable with the 6501's you can bank on it.

I can tell you that i followed that list as you pointed to because I thought all mine were wrong. I also found that MW6501 works much better as the SDA driver than the mw6600. I agree that you can bank on Jesse but there're some differences in the spec's of those drivers interchangeable yes but with some sacifice. Helen said to me that they were very close and could use but with some trade off's. I take what she told me as FACT since she has built them for 30+ years

drumminman

What are the differences in that speaker between the 6600 and 6501 to your ears? What are the tradeoffs?

chuckeroo

Very interesting guys, thanks for all the info! Interestingly, I just looked at all the mw6600x's and they all have
a stamp on them, some saying "SDA-1-D" and some saying "SDA-1-L". Not sure if these are differences, just
something I noticed just now...

pitdogg2

drumminman wrote: »

What are the differences in that speaker between the 6600 and 6501 to your ears? What are the tradeoffs?

I just thought it had better sound stage seem to integrate better with the SDA tweeter which i like as other do not. When i unplug the SDA tweeter to me the sound stage collapse's in a little more than I like. When they did away with the SDA tweeter I also think they used drivers that went a little higher higher in frequencies in that circuit to compensate. But i do not know that for sure to tell the truth. JMHO

I think he should make both match instead of that little mismatch in the SDA circuit

drumminman

drumminman wrote: »

If F1nut says that the 6501's are interchangeable with the 6501's you can bank on it.

Dang! you know what I meant :redface:

westmassguy

chuckeroo wrote: »

Ok, so this upgrade is just about complete, and went way better than I thought. I can't believe I was so worried about the crossover soldering, it was not only not that tough, I actually thought it was the most fun part of the whole process and was a little sad when I was finished because I wanted to keep soldering! I took lots of pictures and will upload them to this thread with full descriptions and things to watch out for soon. Thanks again to everyone for their guidance!

I have a question regarding one of my drivers though...

Of my 8 drivers, 7 are mw6600x, and one is mw6501. I am going to assume the speakers came with the 6600's which is wierd as the schematics for all the early sda's say they have 6501's, but what can you do. Question is, is that one 6501 significantly different, and should I be on the lookout to match another 6600x? Anyone ever ran into this? Would Polk have just thrown in 1 different driver if it was essentially the same, or would this probably be a case of an owner along the line swapping it out?

Edit: The 6501 manufacture date is 1987, so it's def a replacement. All the 6600x are from 1983.

Thanks!

Glad you got it finished. Now sit back, let everything burn-in, and enjoy the music.

leftwinger57

Chuckaroo, When did you get your RDO 194s.A lot of people are waiting w/ their tongues hanging out just waiting for them to come back in stock?

chuckeroo

leftwinger57 wrote: »

Chuckaroo, When did you get your RDO 194s.A lot of people are waiting w/ their tongues hanging out just waiting for them to come back in stock?

I bought the 194's about a year ago, so before they went out of stock evidently. If it's any consolation, they will be worth the wait for any of you who are buying them, really makes a huge difference. Ironically, I now have 2 of the four of them sitting idle in my sda's because I unhooked the dimensional ones as suggested often in this forum. In my opinion, definitely disconnect the dimensional tweeter if you have it like others have recommended. Also, even if you can just fit the 194's in the old slot for the sl's, you need to cut away some of the hole with a router or file so the magnet is away from the cabinet a bit. This caused me issues for the last year (bad tweeter distortion at higher volumes) until this upgrade when I cut away the cabinet and it fixed the issue.


I have now let the stereo run this week for about 50 hours while I was at work, and finally got some time to really sit down today and check out the status of these speakers. I cannot describe how much better these things sound, and I am going to try not to go into some audiophile-speak rant. But seriously, it's like when you go into the high end audio shops and listen to their systems and get bummed because you think you'll never afford speakers that sound like that. I can't believe what a change this made. The highs are clearer, the lows are deeper, everything is much more balanced, the soundstage is unbelievable. I sat listening to music today, staring at the front wall in disbelief that I get to have to have these in my living room. I know they are not considered high end by many, even in SDA standards, but to me these upgrades changed them from pretty nice speakers to truly great. Again, I will post soon with the stuff I did, but for now, more wine and music. Even my wife noticed!

chuckeroo

Ok, here are the upgrades I made with pictures and some notes on what I ran into. I'm sure that much of this will be extremely remedial for many of you, and most if not all of it has probably been posted in this forum before. I mainly wanted to document it in case it ever helps someone in the future, and to give back something to this forum as it has helped me out a lot in this process.

First, the parts:
These are the caps and resistors I bought with cost and place of purchase:

Component -- qty --indiv cost -- total cost
12 uf Cap -- 4-- 22.5-- 90 -- sonicap soniccraft.com
27uf Cap -- 4-- 14.23-- 56.92-- solen partsexpress.com
.5 uf Cap (.47)-- 2-- 8.58-- 17.16-- sonicap soniccraft.com
2.7 ohm 12 watt resistor-- 4-- 4.95-- 19.8-- mills soniccraft.com
4 ohm 12 watt resistor-- 4-- 4.25-- 17 -- mills soniccraft.com

I used the solens for the large low end caps as the sonicaps were pretty expensive in this size and people have said it shouldn't affect performance too much.

Hurricane Nuts: http://www.parts-express.com/pe/showdetl.cfm?partnumber=081-1080 (2 packs)
Bolts: http://www.parts-express.com/pe/showdetl.cfm?partnumber=260-844 (qty:75)
Bit for the Bolts: http://www.parts-express.com/pe/showdetl.cfm?partnumber=360-227
Sound Dampening: http://www.parts-express.com/pe/showdetl.cfm?partnumber=268-030 ( I bought 2, you should buy 3)

On the operating Table:
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Drivers and Tweeters removed:
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Crossovers in Cabinet:
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Removal of back panel:
Notes: Only remove surrounding screws with phillips heads, don't unscrew the allen head screws. These hold the crossovers to the board and you don't need to separate them.
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Removing PCBs for soldering:
Notes: Gently use needle nose pliers to push in tabs on the four plastic pieces holding down the board. This is generally pretty easy, but for the pcb on top of the large coil inductor, there are two black wires you will need to unsolder from the board (see second picture below).

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Recap/ReResistor:
Notes: Desoldering/Soldering is pretty easy as the pads are huge on the bottom. Use mounting tape as westmassguy mentions in other posts to hold the big caps on the board. IMPORTANT: Don't cover the holes that the white holders go through to reattach the boards with your newly soldered components! Resoldering the black inductor wires you previously removed is the hardest part of the soldering, be patient and precise.

Before:
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After:
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Will post the remainder asap....

Thanks
Chuck

zingo

Links/pictures aren't working for me...

chuckeroo

Sorry about that, they seem to only work for me when logged in, must not be using the attachment thing properly. I also can't figure out how to edit the post, so unless there's something I'm missing I can't fix it.

Anyways, here are the pictures, they aren't in exactly the order posted, but should be close enough to figure out:
http://imgur.com/a/0qMYX

drumminman

Congrats on your mods! In my experience, the sound of my 2.3TL's after the Xover rebuild improved at around 30 hrs, again at around 110 and again at around 190-200, IIRC. I used Sonicaps/Mills throughout.