Looking for opinions on SDA-1C x-over upgrade plan

thsmith

paden501, not sure this will help but here is a link where I attempted to document my XO upgrades.

http://www.polkaudio.com/forums/showthread.php?t=89067

Paden501

Ok I just ordered my Mills from parts-express. they didn't have the 7.5ohm (I had to do with 7ohm) and they didn't have the 2.7ohm (2.5 instead), But I was ordering a few other things there so i went ahead and bought them to save on the shipping.

Now I just have to make a decision on Caps and I'll be off and running.

Paden501

Caps are on the way.

I went with the Clarity Cap PX all around. The only minor change is that I used 2 x 2.2uf caps for the 4.4uf, since Madisound was out of stock on 4.7uf PXs.

They should be here in a few days.

ben62670

My Clarity caps will be here in two days also:)

heiney9

ben62670 wrote: »

My Clarity caps will be here in two days also:)

I think you'll like them Ben

H9

ben62670

I am hoping they are more laid back in the mids than the Dayton's and have more detail and sound stage. I think I am asking too much.

Paden501

which line of clarity caps are you using ben? I was really torn between the PX and the SA. I bought the PX in the end and i'm hoping that I didn't make a big mistake.

mmadden28

ben62670 wrote: »

I am hoping they are more laid back in the mids than the Dayton's and have more detail and sound stage. I think I am asking too much.

(Ben) Are you talking about using them on the lows or the highs?

(All) So how would the Clarity Caps PX, SA or ESA compare to Sonicaps (for the highs)?
And how would the Clarity Caps PX or SA compare to Daytons on the lows?

Sonicap has the 20% sale off right now so I might buy the caps I might need now, for an eventual XO mod for my SRS-2s and the 2B's.

Face

ESA's in vintage Polks are the bees knees. Ask Polrbehr who has my old 2B TL's.

Paden501

:-D

My caps came in today. Let me start right off by saying THESE THINGS ARE HUGE! The 40uf is about 1.5" diameter, which is a lot larger than I'd expected.

I also decided to rethink my resistor strategy. I ordered 7ohm and 2.5ohm resistors to replace the stock 7.5ohm and 2.7ohm resistors. After thinking about it for a while, I'm thinking that was a mistake. both of the 7.5ohm resistors are in the direct signal path from the source to the tweeters, so i'm afraid that with the net 1ohm reduction in resistance, the tweeters are going to come off way too hot.

So, I ordered the correct 7.5ohm and 2.7ohm Mills 12w resistors from SonicCraft today. They'll be in Tuesday. Of course, I'm too impatient to wait for the shipment from SC, so i'll be installing the Caps this weekend, and then taking the xovers back out to do the resistors next week.

I'll take some photographs along the way.

Paden501

Crazy question.

What's the best way to unhook the little white hooks that hold the board to the big inductor? I don't want to break them when I take the board off.

Thanks.

Conradicles

Gently squeeze them with needle nose pliers. They are stronger than you think. This stuff is too fun!!! I love upgrading crossovers.

Conradicles

By the way I think I may try those caps in my SDA-2B's soon. I'll be watching this thread. Enjoy.
Eric.

Paden501

Thanks Eric.

I'll let you know how these turn out. The layout looks pretty easy w/ the exception of the big 39uf cap. I'm concerned about making that stay attached to the board. Otherwise this looks like a fairly simple job.

Face

Hot glue and/or zip ties.

Paden501

The mod went fine. The caps are all soldered and glued in. I left a ton of space around the resistors so that I have room to work later.

Unfortunately, I can't seem to find my camera's USB cable right now, so photos will have to wait. I did run into some 'justification' along the way.

I had previously removed the left speaker's xover to inspect it and get the right values... but I've never been in the right cabinet before tonight.

Well... when I pulled the right xover, I knew right a way that I was in trouble, because somebody had been in there before and labeled the connectors. It looks like the previous owner had blown a poly-switch and to fix it he simply twisted the switch around until the leads contacted each other and jumped the switch. Well, the switch was completely burned up, as was part of the 12uf capacitor nearby. Lots of chalky black stuff was on the PCB and the end of the capacitor, and almost no evidence of the polyswitch remained, other than a little bit of the coating.

So right there, I feel justified in doing this modification. The system is back together for now, and sound pretty good. I can't make a judgement on the mod really just yet, as the caps are nowhere near broken in. I will say that immediately I notice more depth though.


My resistors will be in Tuesday. When I do them, I also plan on applying dynamat to the baskets of the woofers and PR, as well as appying mortite around the basket rings.

WilliamM2

heiney9 wrote: »

Yeah, I forgot about who offers what values. It might be better to order Mills from Sonic Craft as they have 7.5 ohm 12W Mills for $3.85/ea. Don't get the 5W

Why not use the 5w? When I was upgading mine, most recommended the 5w over the 12w because the 5w had lower inductance.

Paden501

Finally some photos.

First, a comparison of 40uf capacitors. Not that bigger is always better, but DANG!



Here's everything that came off of the left channel:



And here's everything that went on:



Next, a photo of the aforementioned burned up poly-switch (ewww):



And finally a photo of the finished product:


as you can see from the last photo, i replaced the polyswitch with a .5ohm Mills resistor and used 2 2.2uf capacitors in place of the 4.4uf cap that came off.

This was a pretty easy job for the most part. The only piece that was a little tricky was the placement of the big 40uf cap. it needed to hang off the board quite a bit in order to clear the driver connector.



I havent spent enough time with it for a real conclusion on the sound quality and I still have to replace the rest of the resistors later this week, and of course everything needs several more hours to break in.

WilliamM2

I'm curious why you didn't replace the stock resistors when you did the upgrade. Also, what's the point of replacing the poly switch with a .5 resistor, instead of just using a jumper?

F1nut

I'm curious why you didn't replace the stock resistors when you did the upgrade.

He hasn't got all the new resistors yet. I believe they will arrive today.

Also, what's the point of replacing the poly switch with a .5 resistor, instead of just using a jumper?

It keeps the circuit resistance the same as spec'd. I found the high end a tad bright using the jumper.

headrott

F1nut wrote: »

It keeps the circuit resistance the same as spec'd. I found the high end a tad bright using the jumper.

Wow, I might have to pull out my XOs and put a .5 ohm on there then on my 2Bs and 3.1TLs. I was not aware it would make a big difference.

Greg

Face

Replacing the jumper with a .5ohm resistor is a subtle difference and only needed if you find the speaker's balance off.

heiney9

To go on a small tangent. What value resistor would you (F1 or Face) recommend when eliminating a tweeter fuse, as in a Monitor 5B? Since the fuse is in the signal path for the tweeter couldn't you just bump the resistor that's already in the tweeters signal path?

Here's my situation. When I first replaced all the x-over components in my 5B's I looked at the schematic and it showed a 2.0 Ohm, when I opened the speaker it's actually a 2.7 Ohm. I left it alone but now I want to put the correct value in. Since I've eliminated the fuse on the tweets I was thinking of going with 3.0 Ohm Mills with the extra 0.3 compensating for the resistance the tweeter fuse would normally have.

Does this make sense? I only want to open these up one more time.

Sorry for the slight derail.

H9

Face

Brock, it's your call. I don't know how much resistance the fuse holder+fuse has. But, if the speaker sounds balanced to you, leave it be. If it has a bit of a high end tilt, swap out the resistor for one of a slightly higher value.

heiney9

Yes, I think since day one after I redid the x-over these are a little forward. Not harsh or shrill in any way. The vocals seem slightly more out front. I already have the 3.0 ohm Mills so I'll give them a try and see what I think. So far I have just "tied" the wires that go to the fuse holder together internally with solder and shrink tubing.

I really like the smooth, open character of the Clarity Caps. So much better than the Solen, it's not night and day but noticeably easier on the ears. Less shouty, less grainy and voices and insturments seem to "float" more in the soundstage.

Of course I've changed amps too so that is probably some of it. I heard both caps on the same amp, but not the Solen on my new amp.

H9

Face

While you're in there, swap in some ESA's.

heiney9

Face wrote: »

While you're in there, swap in some ESA's.

I'd love to, but this is a secondary budget oriented rig. I am going to swap the op-amps and some caps in my Adcom dac. So I'll spend the money there.

Really, my office rig sounds soooooooo much better than it should. Sweetness! 12 watts of tube power, Clarity caps, Auricaps, Mills, RD0's, MIT's, AMC dac and FLAC files.....simply fantastic. On paper it looks rather ordinary, but listening to it makes me shake my head. I do have some excellent tubes, probably the best 6SL7 and 6V6GT's around so that goes along way.

To the OP: you are going to LOVE the changes in your SDA's. It will border on disbelief in the beginning. Enjoy!

H9

F1nut

headrott wrote: »

Wow, I might have to pull out my XOs and put a .5 ohm on there then on my 2Bs and 3.1TLs. I was not aware it would make a big difference.

Greg

Your 3.1TL's didn't have poly switches to begin with.

Paden501

Ok so the mod is now complete. I soldered in the mills resistors this evening, and while I was in there I added dynamat to the driver baskets and applied mortite to the driver-baffle mating surface as recommended in so many other threads.

The difference is stunning. I will say that I've been running with the new caps for about a week now and haven't been blown away totally, but with the addition of the new resistors i am SHOCKED. I've listened to several songs that I know very well in the last hour or two, using two different amps (Hafler DH-220 and a Carver TFM-25) and with both amps there is just a ton of little details in the music that was never there.

The vocals did seem to move back in the soundstage a bit, especially on the Carver, and the stage is wider with both amps. I can also hear a lot more 'SDA magic' than before.

Bass has more 'slam' than it did before. This is of course even more pronounced with the more powerful Carver amp, but is noticable with either amplifier.

All in all, I'm very pleased with the mod.

F1nut

Told ya.