SDA SRS 2 need CPR and ICU life support

[proffitt]

looks like it'd be a good idea for me to get that 10 footer after all. Thanks for input. First shipment of items arrived last night. Can't wait to get this day job thing out of the way and get to the basement workshop and start the rebuild. 8 more hours.

[proffitt]

ok, I've gotten alot of work done today. all stripping and sanding done. All staining done. Wiped down residual and drying tonight before some poly is going to make it really pop. Its looking great! Pics to come after poly. But in the meantime... the next step.

All of my components are in, caps, resistors... I'm going to have to reach out to the group for more help on the next round of tasks. Its time to mod the crossovers. I've looked at all of the online guides and instructions, and found that most of the work modding the crossovers is done on rectangular boards. Mine are all round.



So this is my setup here. I need some guidance on what component that I've ordered replaces what component on the board(s). Is there a document that covers my model of the round shaped pcb and details what replaces what?

Thanks for any guidance.

[Schurkey]

Post #7 shows the original and the replacement capacitors; and the completed LF board--the one on the left in your photo.

Sorry, don't have photos of my HF board.

[helipilotdoug]

Here are a couple of photos showing the rebuilt crossovers used during my SRS II re-furb. Hope this helps.

[newrival]

deleted.

[drgalexo]

Those are looking great Proffitt, I also have the SRS 2's with the B/B interconnect. I didn't realize so many members had the same model. I can't wait until you can hear how great they will sound, and I haven't even started to do my upgrades yet.

[proffitt]

Side slats pieces and wood bottoms are done. The wood tops are still at a friend's getting planed down. Electronics mods coming next.

[proffitt]

ok. This seems like a really elementary question on the electrical side but its stumped me. better safe than sorry. First thing I'm doing is making the interconnect mod. I've removed the blade/blade connector. I've drilled out the hole to 7/8th inch to fit the neu Neutrik connector. The schematic shows me that from the original connector, the pin #1 is the wide blade and is where the white wire is connected. Pin #2 is the narrow blade and is where the black wire is connected. It appears that the schematic key is showing that A equals pin #2, is black... and is positive. And that B equals pin #1, is white and is negative. Really? Black is positive and white is negative? What am i missing? The blades on the neu Neutrik connector are labeled positive and negative and I'm about to solder.

[proffitt]

Here are a couple of photos showing the rebuilt crossovers used during my SRS II re-furb. Hope this helps.
Attachment 77660Attachment 77661

Helipilotdoug -
it looks like the components i got arent exactly the same as yours. Can you tell me... on your high freq board, i see you have sonicaps gen1 12uF and another sonicap. Is that second one a value of 5.8uF? It also looks like you have 3 other new resistor components on there. One i can see is a 2.7 ohm. Are all three 2.7 ohms or are they different values?

On the low freq board, it looks like there are more significant differences. looks like on each board you have four 17uF sonicaps and two of the dayton caps. What are your dayton values?

for the lows, I sourced (for each board) two dayton's of 33uF. I wonder if the two 33s will substitute for your four 17 caps?

I also sourced (for each board) one Dayton 90uF and one Dayton 100uF. Are these close to your values for your other caps?

Do yu have anyhing else under there that i can't see?

Schurkey, if you are reading, I'd love some of your thoughts on this. And be very greatful to you all!

[Schurkey]

Helipilotdoug -
it looks like the components i got arent exactly the same as yours. Can you tell me... on your high freq board, i see you have sonicaps gen1 12uF and another sonicap. Is that second one a value of 5.8uF? It also looks like you have 3 other new resistor components on there. One i can see is a 2.7 ohm. Are all three 2.7 ohms or are they different values?

On the low freq board, it looks like there are more significant differences. looks like on each board you have four 17uF sonicaps and two of the dayton caps. What are your dayton values?

for the lows, I sourced (for each board) two dayton's of 33uF. I wonder if the two 33s will substitute for your four 17 caps?

I also sourced (for each board) one Dayton 90uF and one Dayton 100uF. Are these close to your values for your other caps?

Do yu have anyhing else under there that i can't see?

Schurkey, if you are reading, I'd love some of your thoughts on this. And be very greatful to you all!

I'd say your instincts are good.

[helipilotdoug]

Helipilotdoug -
it looks like the components i got arent exactly the same as yours. Can you tell me... on your high freq board, i see you have sonicaps gen1 12uF and another sonicap. Is that second one a value of 5.8uF? It also looks like you have 3 other new resistor components on there. One i can see is a 2.7 ohm. Are all three 2.7 ohms or are they different values?

On the low freq board, it looks like there are more significant differences. looks like on each board you have four 17uF sonicaps and two of the dayton caps. What are your dayton values?

for the lows, I sourced (for each board) two dayton's of 33uF. I wonder if the two 33s will substitute for your four 17 caps?

I also sourced (for each board) one Dayton 90uF and one Dayton 100uF. Are these close to your values for your other caps?

Do yu have anyhing else under there that i can't see?

Schurkey, if you are reading, I'd love some of your thoughts on this. And be very greatful to you all!

On the highs, there is a 5.8uf and a 12uf on each. The resistors are all 2.7ohm, three on each board.

On the lows the Daytons are two 90uf on each. We went with the equal value caps, because supposedly that's the best way to go. They are so large, had to mount them off the board. The values are very close to the 185uf called for, and I'm sure the 100uf with a 90uf you have will work just fine. On the 17uf caps, they equal the value called for of 34uf. I'm sure your 33uf caps will work well. Nothing else hidden under there.

Hope this helps. Really looking forward to seeing and hearing about your results.

[proffitt]

thanks so much guys!!!! I couldn't be doing this without you!

Do you guys know where i can get the diagram of where I'm soldering to? I can see what components you have on there... but i cant see what board holes the leads are leading to. any hints?

[PolkieMan]

Beautiful!!! Kinda get me teary eyed

Attachment 77686

Attachment 77687

Side slats pieces and wood bottoms are done. The wood tops are still at a friend's getting planed down. Electronics mods coming next.

[pitdogg2]

thanks so much guys!!!! I couldn't be doing this without you!

Do you guys know where i can get the diagram of where I'm soldering to? I can see what components you have on there... but i cant see what board holes the leads are leading to. any hints?

You seem to be WAY over your head here so I'll try and help.
when changing the caps the easiest way is to get a sharpie with a fine tip to MARK EVERYTHING.
I found it easier to take the large inductor off to see all the solder pads. let me state here to have two different color sharpies that way you can mark each lead of the inductor so they go back in the same hole. Look at the caps on the board write values on back side of boards that correspond with the cap on top. work one board at a time.

On the interconnect it's easy they are mirror image what you do on one side do the opposite on the other. Example...Blue wire goes to wide blade on one side goes to narrow blade on the other and vice versa.

[proffitt]

Thanks very much Pitdogg. Yes, feeling over my head on this part. If i just knew what old component was replaced with what new component....

Shurkey did a good job of showing me in post #7 above, that the two blue caps (130 uF and 34 uF) are replaced by the new caps (Erse 91 uF and Dayton 33 uF, respectively). That i can do, no problem. But with the rest, I don't know what old components come off, and what replaces them. If i knew that, I'd know where to solder and what to do.

If there was a "old to new" line item list....

[drgalexo]

I give you a lot of credit proffitt, I would like to try the crossovers myself but really in over my head. Keep posting the great photos, it's very helpful.

[drumminman]

When doing Xovers on both my RTA 12C's and 2.3TL's I found a couple of things helpful.

- Do one board at a time so you can use the other as a reference in case you get confused.

- Replace components one at a time rather than stripping the board completely clean (if you're using the original pcb's). Makes it much more difficult to screw up!


Good luck!

[proffitt]

Will do drgalexo. Thanks!
And if i can ever figure it out, I will create a layman's list of "remove this, replace it with this" list, and post it here. For example, see on the hi freq board (post #92 above on this page, board on the right), the four rectangular components that are the same color of the board? I have no idea if those come off or not. Is the small yellow device on that same board, the polyswitch that is so much discussed? What about the dark yellow and light yellow components.... with the little brown beads riding piggyback? Do those come off and what are they replaced with? If I knew that, I could assign their solder holes to the new components and it'd be easy. I just don't have an overall plan.

Until then I guess that's why we pay the big bucks to the electrical engineers!

[drumminman]

Those 4 rectangular components are resistors, and yes you will replace those with higher quality ones. They have a big effect on the highs.

The small round disc looks like the polyswitch. Most here replace it with a 0.5 watt resistor, but a word of warning. If you do this you must use high quality amplification and not overdrive it. If you do you could blow your tweeter(s). I've never had issues and I can play my SDA's loud enough to drive people from the room.

The dark yellow and light yellow components with the little brown things sitting on top are capacitors. You'll replace the big yellow ones with new film caps, and throw away the little brown ones. They're bypass caps and are unnecessary when you use high quality film caps.

See, all that stuff is easy. The main thing is to go slow and don't forge ahead until you're sure what you're doing. And if you're not sure ask here on the forum. Lots of knowledgeable folks that are willing to help.

[proffitt]

ou guys are alot of help and I'm so close i can taste it. Tops came back from planing today, and got their final sanding and first coat of stain. Look great.

I think i have a good grasp of the low freq boards. The pictures helped alot Schurkey and helipilotdoug. Thanks very much! I'm ready to make these mods to the low boards.

I'm still a bit confused on the high freq boards though. Maybe a little more help will put me in line.

Helidoug... I see on your pics that there seem to be 3 replacement Mills resistors with 2.7 ohm. Is there a 4th one that i can't see? my original board had 4 rectangular resistors, 3 of which are 2.7ohm, and one which is 3.5 ohm. If there is one i can't see, what value is it? If there are only three, which one did you not replace? and did you jumper the void, or just leave it unpopulated?

Schurkey... I'm realizing that there are different approaches to components to choose for replacement. It never was a set list of replacement components, and "to each their own" on what to choose and what route to go. I appreciate your input and helping get me there. From what i can tell, i think i got the best quality and am happy i stumbled into your good advice. I am confused on one matter though, and i fear i might be missing something. For the high boards, here's what we/I decided on ordering:

Highs:
8 Mills resistors 2.7 ohm
2 Mills resistors 1.5 ohm
2 Mills resistors ~1.75 ohm if available
2 Mills resistors 2.0 ohm
2 Mills resistors 2.5 ohm
2 Sonicaps 5.8uF
2 12uF

Its the resistors that have me confused. There are 4 original resistors on the board, as detailed above. Looks like (depending on feedback from my first question) I'll be using either 3 or 4 new resistors per speaker, or 6-8 total. What are the other 8 new resistors for? What's worrying me is that there's something I'm not seeing under one of the big caps or something.

Final question (for this evening!)... it appears that the yellow disk component is the polyswitch. I've read in one place that it should just be removed. Another read says to jumper a straight wire to the pads where the poly came from. And another piece of advice is to replace the poly with a resistor of some un-remembered value. Any consensus on this from the group? I'll not be cranking the volume to destructive levels, and I'll be using a quality, powerful amp. And if the worst that can happen i can blow a tweeter or two, i know where to get two more. Advice?

Thanks ALL!!!!!

[Schurkey]

The small round disc looks like the polyswitch. Most here replace it with a 0.5 OHM resistor

FIFY.

While I hate to be a lone voice crying in the wilderness, the treble of my 1Bs was not loud enough. Removing the polyswitch--and the resistance associated with the polyswitch--was not enough of a boost in my system. If I'd been smart enough, I'd have reduced the input resistor from 2.0 ohms to 1.5 or 1.75 ohms. Instead, I invented a much less-elegant and more-expensive solution. You need to do what sounds right; my first guess is that you have NO NEED to compensate for the resistance of the polyswitch; and if you followed my advice to purchase a range of resistors for the input, you can compensate for the polyswitch resistance, if desired, with the input resistor--two fewer solder joints in the audio path.

[proffitt]

drumminman... looks like our posts passed in cyberspace. You covered exactly what several of my questions were. Just didn't want you to think i was reasking after your post. Thanks!

[Schurkey]

.

I'm still a bit confused on the high freq boards though. Maybe a little more help will put me in line.

Helidoug... I see on your pics that there seem to be 3 replacement Mills resistors with 2.7 ohm. Is there a 4th one that i can't see? my original board had 4 rectangular resistors, 3 of which are 2.7ohm, and one which is 3.5 ohm. If there is one i can't see, what value is it? If there are only three, which one did you not replace? and did you jumper the void, or just leave it unpopulated?

Schurkey... I'm realizing that there are different approaches to components to choose for replacement. It never was a set list of replacement components, and "to each their own" on what to choose and what route to go. I appreciate your input and helping get me there. From what i can tell, i think i got the best quality and am happy i stumbled into your good advice. I am confused on one matter though, and i fear i might be missing something. For the high boards, here's what we/I decided on ordering:

Highs:
8 Mills resistors 2.7 ohm
2 Mills resistors 1.5 ohm
2 Mills resistors ~1.75 ohm if available
2 Mills resistors 2.0 ohm
2 Mills resistors 2.5 ohm
2 Sonicaps 5.8uF
2 12uF

Its the resistors that have me confused. There are 4 original resistors on the board, as detailed above. Looks like (depending on feedback from my first question) I'll be using either 3 or 4 new resistors per speaker, or 6-8 total. What are the other 8 new resistors for? What's worrying me is that there's something I'm not seeing under one of the big caps or something.

Replace the three 2.7 ohm resistors on each HF board with 2.7 ohm resistors. 6 2.7 ohm resistors total.

Replace the single 3.5 ohm resistor per board with WHATEVER SOUNDS BEST IN YOUR SYSTEM. Mark the location of that 3.5 ohm resistor, and do some "experimenting". That single resistor--the 3.5 ohm unit--is the single electrical difference between the SRS 2 B/B and the SDA 1B. The 1B comes with a 2.0 ohm resistor instead of a 3.5 in that position. I wish I'd have installed a 1.5 or 1.75 ohm in place of the 2 ohm in my system.

inspiredsports appeared to sanction 1.5--1.75 ohm resistors in that location; but in the end went with another 2.7 ohm, four total per board. He didn't give any reasoning behind his change-of-mind.

You are left with some options:

Install a 3.5 ohm resistor where the original 3.5 ohm units were--one per HF crossover. inspiredsports and I agree that 3.5 is too damn much, and the treble is not loud enough. This is why I didn't encourage you to buy 3.5 ohm resistors. You could ignore us both, in favor of the original engineering done by Matthew Himself.

Install a 2.7 ohm resistor in place of the 3.5 ohm, as inspiredsports has done with his SRS 2 B/B speakers, having conducted considerable testing and evaluation. As I recall, he DID NOT install a .5 ohm resistor to compensate for the resistance of the polyswitch.

Repeat inspiredsports listening tests, select the resistor value from the "extras" you bought, that sounds/measures best in your room. Solder-in the 2.7 where the 3.5 used to be. If you're in heaven when you listen, you're done. If the treble sounds feeble after some time to get used to the new, improved SRS 2 B/B, remove the 2.7 ohm resistor from the position originally occupied by the 3.5, and stuff in the 2.5 or the 2.0 instead. Listen awhile. Repeat if needed with a lower-value resistor, until the treble sounds/measures balanced to the mids/lows to you, in your room with your ears/measuring equipment.

"I" think you'll end up with 2 ohms or less, where the 3.5 ohm resistor is now. But that's me, and I don't have an EE degree. You'll therefore have some extra resistors when you finish.

If you don't use the two 1.5 and the two 1.75 ohm resistors, I'll buy them from you. The 2-ohm resistors on my circuit boards are going to disappear when I get around to soldering-in the replacement SDA inductors this winter.

[proffitt]

Awesome Schurkey. Thanks for the advice to allow me to fine tune my new setup before I even knew that's what I was doing. And thanks for the clarity here. I think I'm ready to make my crossover mods. All you guys are great!!!

[helipilotdoug]

I'm still a bit confused on the high freq boards though. Maybe a little more help will put me in line.

Helidoug... I see on your pics that there seem to be 3 replacement Mills resistors with 2.7 ohm. Is there a 4th one that i can't see? my original board had 4 rectangular resistors, 3 of which are 2.7ohm, and one which is 3.5 ohm. If there is one i can't see, what value is it? If there are only three, which one did you not replace? and did you jumper the void, or just leave it unpopulated?


Thanks ALL!!!!!

I see what you are talking about on the photos of the boards. A guy named Ben did the boards for me, and I do know that a 2.7 ohm replaced the 3.5 ohm, and there were a total of 4 2.7 ohm resistors installed on each high board. It's been awhile since this was done, and I can't remember where the other resistor might have been put. Because of the limited space, it might have been installed on the back side of the board, but I'm sure it's there somewhere. Wish I had done a better job of documenting this.

As to the 3.5 ohm resistor replacement, in my system the 2.7 ohm seems to be just about right. As Schurkey mentioned, trying some different values might yield better results, and it might be fun to try. Also, the polyswitch was not replaced, with good results in my system, and at least in my case, would more than likely never have the amp cranked up enough to blow the tweeters.

[proffitt]

I think i have my answer. Thanks to you and Schurkey.. and others here. I'll remove the three old 2.7 ohm resistors and replace with new 2.7 ohms. On the 3.5 ohm one, I'm going to take Schurkey's advice, with a twist of conservativeness, and replace it with a 2.5 to start with. Its significantly lower rated than original, but still gives me plenty of room to move on down from there if i decide to tweek.

When you say that the polyswitch was not replaced... do you mean you still have it in there? Or it was removed and nothing was added in its place? If this is the case, do you know if the pads were connected with just a wire jumper, or was the path not reconnected at all?

I want to remove mine, but i don't know if i leave the space void, or jumper it with wire.

[Schurkey]

When you say that the polyswitch was not replaced... do you mean you still have it in there? Or it was removed and nothing was added in its place?

Pretty sure he removed it and did not install a replacement.

do you know if the pads were connected with just a wire jumper, or was the path not reconnected at all?

I want to remove mine, but i don't know if i leave the space void, or jumper it with wire.

You cannot leave the polyswitch space void. The tweeters will not function.

You can install a dedicated jumper wire across the polyswitch solder-joints. Some folks do this by giving the polyswitch a half-turn or more, and then tacking a touch of solder to the lead wires where they cross. Doing this shorts out the polyswitch so it is no longer effective. The polyswitch leads become the jumper. Another option is to remove the polyswitch completely, clip one lead, bend that lead so it bridges the two solder points, and then solder the clipped-off wire into place.

You can install the input lead for the resistor into the input solder-joint for the polyswitch, and the output lead for the resistor into the output solder joint for the resistor--the resistor bridges the remaining two solder joints. Those two solder joints aren't filled, and cannot degrade the signal. I like this better.

[proffitt]

hey guys.. the crossover electronic mods are going fine.... slow but fine. Quick question- none of these caps are directional or polarized are they? They can install either direction in the circuit, correct? Thanks!

[PolkieMan]

Yes the caps and resistors can go either way along with the inductors

hey guys.. the crossover electronic mods are going fine.... slow but fine. Quick question- none of these caps are directional or polarized are they? They can install either direction in the circuit, correct? Thanks!

[helipilotdoug]

Pretty sure he removed it and did not install a replacement.


You cannot leave the polyswitch space void. The tweeters will not function.

Yes.this is correct. There was a jumper installed in place of the poly switch.