Troubleshooting SDA SRS 3.1TL

jimbo1421

Hello,

Shortly I will be taking delivery on a pair of SRS 3.1TL and, preparing for testing, I was looking for the reference data for DCR Checkpoints. I have the "SDA Quick Troubleshooting.pdf" file but it does not include the values for the 3.1TL. Does anyone have them? Do values for any of the other models also work for the 3.1TL? The last page of this PDF lists an "SRS" with no numbers. Could that be the one to use?

Jim

jimbo1421

They are here now. I am giving them a visual inspection first. These speakers did have a cat once; its pulls are quite evident, but not so much in the pictures. Also, the top left corner of the right speaker is munched a bit, which was not at all evident in the pics.

The interconnect is home made from blade/blade connectors. The smaller blade was filed down to fit the pin hole. There is continuity from large blade to large blade and small to small. Is this right and OK to use? My CRS+ only had a connection between the pins, not the blades.

The press test on the right took 1-1/2 to 2 seconds recovery. All drivers moved smoothly and quietly when pressing on the passive bass radiator. The left side was quicker and, now that the afternoon light is on it, I can see a small tear in the rubber surround. I was thinking of applying some silicone sealer or Shoe Goo (http://www.acehardware.com/product/index.jsp?productId=2364597) to it until I can replace it. Is that a good idea?

The seller mentioned a "cosmetic mark" on one woofer, meaning the bass radiator, I guess. It looks more like a repair to a torn cone.

Time now to plug them in and see if they make sound.

Jim

Schurkey

jimbo1421 wrote: »

The interconnect is home made from blade/blade connectors. The smaller blade was filed down to fit the pin hole. There is continuity from large blade to large blade and small to small. Is this right and OK to use? My CRS+ only had a connection between the pins, not the blades.

It's not "right", but it should work. As long as the filed-down blades have low resistance between them, you should be fine as long as you have a common-ground amp. If you're using balanced/bridged amps, you will need the AI-1 or aftermarket isolation transformer.

jimbo1421

Thanks, Shurkey. Following NAD's instructions I strapped the negative terminals on the T955 to create a common ground. Resistance between the filed down "pins" measures 0.1 ohms.

I have done the listening tests from "SDA Quick Troubleshooting.pdf" and they passed. But in the "difference" test with black leads unplugged, the "spacey" quality they describe in one of the tests isn't as pronounced as I remember it from other SDAs. Instead of coming from nowhere in particular, the test sound (white noise) seems to come from the two sides. I still don't have the reference values for the DCR tests. Does anyone know what they should be?

After a few hours of listening to various types of tunes I have good and not so good first impressions. Biggest improvement is in the high frequencies. Not at all fatiguing as the SL-2000 or RDO-194. I will try some Bach violin sonatas next. That always gives the tweeters a workout. Bass response is nicely balanced and musical. Could be a little tighter but fixing the hole in the MW surround might take care of that.

The soundstage here is not as broad as my other SDAs and imaging not as precise. My reference here is Dave Brubeck's Take Five. The piano usually ends up in the dining room! Not with these 3.1s. I have noticed that old speakers that have sat unused for awhile need some break in time just like new ones. So perhaps time will improve these qualities.

Jim

drumminman

Re: the rubber surround tear, I used the stuff I described in this thread: forum.polkaudio.com/discussion/163519/found-product-for-butyl-rubber-surround-repair#latest

Works great.

Re: the imaging quality, have the Xovers been modded? If not doing that would probably restore imaging, improve SQ, etc.

Mike Reeter

drumminman wrote: »

Re: the imaging quality, have the Xovers been modded? If not doing that would probably restore imaging, improve SQ, etc.

Without question, the imaging on my 3.1's is scary good.

jimbo1421

Thanks, drumminman. I wonder if the Shoe Goo I mentioned above is just about the same stuff. I used it on a crack in my rubber/leather boots, building it up in layers like your link described. It stays flexible but sticks tenaciously.

I also have a derelict pair of Monitor 10Bs with bad cabinets and I think they have the MW6503 drivers. I will have to dig them out to see.

These 3.1TLs have upgraded tweeters which are the RD0-198.

After the replacement MW the next item will be the interconnect. The connections with the modified blade/blade plugs are pretty shaky and I will need to replace the female connector in the cup. Can anyone recommend a good replacement? I already have a complete set of blade/blade connectors that I could swap directly. Is there a better solution that will fit the existing cups? Also do both pin and blade carry a signal or are they like the CRS+ which just uses the pin?

Jim

jimbo1421

Mike Reeter wrote: »

drumminman wrote: »

Re: the imaging quality, have the Xovers been modded? If not doing that would probably restore imaging, improve SQ, etc.

Without question, the imaging on my 3.1's is scary good.

No, they haven't been upgraded. That will be next, after the interconnect.

Jim

westmassguy

jimbo1421 wrote: »

Thanks, drumminman. I wonder if the Shoe Goo I mentioned above is just about the same stuff. I used it on a crack in my rubber/leather boots, building it up in layers like your link described. It stays flexible but sticks tenaciously.

I also have a derelict pair of Monitor 10Bs with bad cabinets and I think they have the MW6503 drivers. I will have to dig them out to see.

These 3.1TLs have upgraded tweeters which are the RD0-198.

After the replacement MW the next item will be the interconnect. The connections with the modified blade/blade plugs are pretty shaky and I will need to replace the female connector in the cup. Can anyone recommend a good replacement? I already have a complete set of blade/blade connectors that I could swap directly. Is there a better solution that will fit the existing cups? Also do both pin and blade carry a signal or are they like the CRS+ which just uses the pin?

Jim

4th and 5th generation SDAs use only the pin. The blade was for support. I would suggest replacing all the IC connectors with SpeakONs, and a quality Speaker Cable.

F1nut

I'll second westmassguy's suggestion.

Schurkey

westmassguy wrote: »

4th and 5th generation SDAs use only the pin. The blade was for support. I would suggest replacing all the IC connectors with SpeakONs, and a quality Speaker Cable.

The blade was not used on the ordinary interconnect cable. The blade WAS USED when the Polk-supplied AI-1 was connected to the speakers in place of the ordinary cable. Therefore the blade connects electrically to the negative speaker cable binding post inside the speaker cabinet.

The blade does more than just "support" the pin. It's electrically active when the AI-1 is in place.

Of course, the original pin/blade connector set can be happily replaced with other styles of connector, with the Speakon being a current favorite. In such a case, the SpeakOn must be wired in a way that preserves both the + and - sides of the signal, so that an isolation transformer (AI-1 or aftermarket replacement) can still be used.

jimbo1421

I am back on this project this evening. I am pulling an MW 6503 from a derelict pair of 1988 Monitor 10s to replace the one with the torn surround. This should be OK, right?

I looked at the SpeakON connectors. Is this the model you are referring to?
http://www.neutrik.com/en/speakon/speakon-chassis-connectors/nl2md-v
It has a 24mm diameter socket with rivet holes 30.6mm apart. The hole in the cup for the IC socket is 16.5mm with rivets 24.7mm apart. Is there another model that fits this hole? Alternately, is there a replacement cup that would work for the SpeakON plus the four bi-amp terminals?

Jim

jimbo1421

When DHL dropped these off last week, the driver, Frank, asked, "Is this a small refrigerator?"

Jim

F1nut

These are what you want. Even though you will only use 2 poles, these spec better than the 2 pole versions and are air tight. The gasket will cover the original rivet holes, but you should seal the rivet holes anyway.

http://www.neutrik.com/en/speakon/speakon-chassis-connectors/nl4mp-uc

http://www.neutrik.com/en/speakon/speakon-chassis-connectors-accessories/scdp

http://www.neutrik.com/en/speakon/stx-series/nlt4fx-bag

jimbo1421

Thanks, F1nut. I will still have to enlarge the IC hole from 16.5mm to 23.8mm.

Alternately, I could drill a separate hole in the cabinet for the SpeakON connector and replace the terminal cups. This seems like the cleanest method if the wires will stretch to a new location. Is there any reason not to? I looked at Parts Express and Mouser for bi-amp terminal cups without finding any. Can anyone suggest a source for them.

Jim

F1nut

Yes, you have to enlarge the existing hole, no biggie. Somewhere in here are pics of the one I did. It looks like it was always there. Another option would be to buy new metal binding post plates from Vr3 Mods, which come with the SpeakOn and binding post holes pre-drilled. No one else sells a replacement binding post plate that fits the SDA's.

jimbo1421

Thanks again. I'll be ordering next week once I have had a look inside.

Jim

jimbo1421

What cable works well with the SpeakON plug? I intend to order new speaker cables & bananas from Blue Jeans, either the Belden or Canare, but these don't look suitable for the SpeakON plug which fits on 9-16mm (3/8" - 5/8") cable.

Jim

cortico

They use the canare 4s11, the 4s8 (4 x 16awg conductors) has smaller diameter and will be fine. I had great results with this cable, good built and pretty easy to work. It's dead quiet in long runs studio applications...

jimbo1421

Thanks, cortico. So now my shopping list incudes sufficient length of the Canare 4s11 14 gauge to make up two speaker cables and the IC plus a little bit for jumpers. I might decide later to try bi-amping. Locking bananas, spade lugs for the jumpers and SpeakONs (per F1nut) for the IC. Sound right? Did I miss anything?

Jim

F1nut

jimbo1421 wrote: »

What cable works well with the SpeakON plug? I intend to order new speaker cables & bananas from Blue Jeans, either the Belden or Canare, but these don't look suitable for the SpeakON plug which fits on 9-16mm (3/8" - 5/8") cable.

Jim

Just about any cable will work, I prefer MIT Shotgun cable. Anyway, there is a rubber nipple at the opening, which can be removed by basically ripping it off. Then there is a metal snap ring, which held the rubber nipple in place. You can remove that with needle nose pliers to gain another mm in diameter. In my case that still wasn't enough, so I used a Dremel to grind out the end to 21mm.

jimbo1421

Thanks, it's good to know I can modify them.

cortico

F1nut wrote: »

These are what you want. Even though you will only use 2 poles, these spec better than the 2 pole versions and are air tight. The gasket will cover the original rivet holes, but you should seal the rivet holes anyway.

http://www.neutrik.com/en/speakon/speakon-chassis-connectors/nl4mp-uc

http://www.neutrik.com/en/speakon/speakon-chassis-connectors-accessories/scdp

http://www.neutrik.com/en/speakon/stx-series/nlt4fx-bag

Do you have a tab preference? I have ordered screw in tabs on both male and female connectors.

F1nut

There is yet another reason for the ones I linked, solder pads.

cortico

I see, i will have to enlarge the existing cabinet holes. I am thinking that 1" diameter bit should be good, this will give about 1/32" gap between connector and particle board. Won't you think?

F1nut

What do you mean, cabinet holes? The SpeakOn socket should go on the binding post plate, replacing the original pin/blade socket. Use the rubber sealing boot as a template, mark the circle with a pencil, then use a Dremel with a sanding disc to enlarge the original hole. Keep the Dremel speed down as too fast might melt the plastic.

cortico

No, mine is a blade/blade. The orinal connector is monted on the cabinet rear panel, not on binding post plate...

Nightfall

I think information is getting confused because the thread is about a pair of 3.1's and not what looks like CRS.

cortico

Yes, sorry I shouldn't be posting here.

F1nut

Ah, thanks Nightfall. Yes, I was talking about the 3.1TL's.

jimbo1421

Hello again,

This afternoon I got going on these 3.1TLs, intending to Loctite and Dynamat the drivers. Opening up the left speaker I saw that someone with a soldering iron had got there before me. I was surprised to see a white wire soldered to the red dot (positive) terminal along with a black wire. This was on the third MW6503 from the top, just below the tweeter. I was really expecting to see all black wires to the red dots. I am not much good at reading schematics but the one I found with all the other stickies seemed to be that way. I have attached a wiring diagram as I found the left speaker. I see that the right speaker is also wired this same way with no sign of tampering. So I guess it must be right. Still can someone confirm that my 3.1TLs are properly wired?

Jim