My 2As Finally Finished...Almost

[westmassguy]

I agree 100%. Kinda funny many of these old Polks are assembled using a version of the stuff. I knew a guy when i was a teenager who used hot glue in his car stereo install. The finished job looked awesome until summer.

LOL
The glue they used for the cabinet assembly is much different. The stuff they used on the crossovers is just awful stuff. Every Polk Crossover I rebuild, is covered in the stuff, and its separated, falling off etc. Even the wire ties they used back then were poor quality.

[TennMan]

eBay. I've not been able to find it anywhere else. I've bought from this seller many time over the years.
http://www.ebay.com/itm/360286206011...84.m1438.l2649

It's great looking cloth but something is bugging me. Their ad for the cloth states:

It is on a 60" wide roll. If you order 2 yards, you will receive 1 pieces of cloth that measures 72" X 71" and it will cost $49.98 plus shipping.

If you want 1 unit then you will get 1 piece that is 36" X 71" at a cost of $24.99 plus shipping - Simple.

I wonder how they get 71" wide cloth off of a 60" wide roll? I must be missing what they are actually saying.

[halo71]

It's great looking cloth but something is bugging me. Their ad for the cloth states:
I wonder how they get 71" wide cloth off of a 60" wide roll? I must be missing what they are actually saying.

pffftttt....hello! They cut it at a sharp angle of course!

[Mystery]

pffftttt....hello! They cut it at a sharp angle of course!

That's funny.

[westmassguy]

It's great looking cloth but something is bugging me. Their ad for the cloth states:
I wonder how they get 71" wide cloth off of a 60" wide roll? I must be missing what they are actually saying.

Most likely a typo. I ordered 2 yards, and it's 71" X little over 72". The stuff is beautiful to work with too.

[Mr. Bubbles]

LOL
The glue they used for the cabinet assembly is much different. The stuff they used on the crossovers is just awful stuff. Every Polk Crossover I rebuild, is covered in the stuff, and its separated, falling off etc. Even the wire ties they used back then were poor quality.

I am sure it is different compound, but i had similar issues with my cabinets on my SRS's; coming loose, etc.

[westmassguy]

I am sure it is different compound, but i had similar issues with my cabinets on my SRS's; coming loose, etc.

That sucks. How did you handle repairing them? Internally reseal them?

[Schurkey]

It's great looking cloth but something is bugging me. Their ad for the cloth states:
I wonder how they get 71" wide cloth off of a 60" wide roll? I must be missing what they are actually saying.

First Guess: Not 60" (5 feet), it's 6.0' instead. Six feet = 72 inches.

[Mr. Bubbles]

That sucks. How did you handle repairing them? Internally reseal them?

yes; I first removed all of the loose glue and then used a proper wood adhesive (carpenters glue) mixed half with water to prime the particle board. Once that had penetrated the wood and dried I then glued the joints with the carpenters glue not thinned. Once that was done i went over everything once more using the glue like caulk, pressing it into the joints with my fingers to be sure there were no leaks.

My cabinets were very bad though. I had joints that had come loose but also joints that appeared to have no glue at all in them between the baffle and bracing on both cabinets (the front to back brace was not attached to the baffle in either cabinet, just butted up to the baffle but enough space to slide a normal business card through the whole way.) Also had no visible glue in the joint between the top and back panel on one of the cabinets. They must have been early Monday or late Friday cabinets. They are good now though.

[westmassguy]

yes; I first removed all of the loose glue and then used a proper wood adhesive (carpenters glue) mixed half with water to prime the particle board. Once that had penetrated the wood and dried I then glued the joints with the carpenters glue not thinned. Once that was done i went over everything once more using the glue like caulk, pressing it into the joints with my fingers to be sure there were no leaks.

My cabinets were very bad though. I had joints that had come loose but also joints that appeared to have no glue at all in them between the baffle and bracing on both cabinets (the front to back brace was not attached to the baffle in either cabinet, just butted up to the baffle but enough space to slide a normal business card through the whole way.) Also had no visible glue in the joint between the top and back panel on one of the cabinets. They must have been early Monday or late Friday cabinets. They are good now though.

Guess I've been lucky. All my Monitors, and SDAs were assembled very well. I plan on adding some type of cross-brace to my 2As in the lower half where the PR is. After I did all the new work, I ran some sweep test tones through them, and did notice some panel resonance in that section of the cab.

[westmassguy]

Taking the plunge, and doing the non-sanctioned "TL" Mod for these, as well as my Custom Center Channel. Ordered the caps, tweets and inductor for the center today. We'll see how this goes

[pitdogg2]

I'll be watching might go down this road also some day

[westmassguy]

I'll be watching might go down this road also some day

The only difference in the Hi-Pass Section of the 2A vs 2B, is a resistor in series with the inductor which is part of the 2nd order bypass. All other components/values are the same. I'm going to leave the resistors in place, and use an alligator clip jumper to see if the resistor makes any appreciable difference.

[PolkieMan]

Will be interesting to see your findings

The only difference in the Hi-Pass Section of the 2A vs 2B, is a resistor in series with the inductor which is part of the 2nd order bypass. All other components/values are the same. I'm going to leave the resistors in place, and use an alligator clip jumper to see if the resistor makes any appreciable difference.

[westmassguy]

Will be interesting to see your findings

I think a lot of 2A and CRS owners will be.

[westmassguy]

Well boys and girls the operation was a complete success. Received the RDO-198s this morning, and already had everything else.
The modification was rather simple. To clear some space for the new 5.8uf cap, I relocated two of the resistors to the bottom of the board. On the shunt resistor, I left enough lead popping through the top of the board to get a set of alligator clip jumpers on for testing. I did the left speaker first, and put the jumper on to simulate the 4th generation/2B High-Pass configuration. Buttoned it up, and fired up the HTPC. Started playing a few very familiar tracks, and immediately noticed the stereo image had shifted to the left. The left speaker was slightly hotter on the top, and a bit louder. There was significantly more detail as well. I suspected this would be the outcome of the test, but for completeness and any doubters out there I wanted to be sure. I pulled the PR, removed the jumper, buttoned her back up, and started again. Stereo image was back dead center, the hot top end was gone, but the increased detail remained. I then rebuilt the right crossover, put her back together and sat down for some critical listening. Way more detail across the board. I would not say the difference was as dramatic as going from the SL2000s to the RDO-194s, but there is a very noticeable improvement, and it was well worth the effort. As I stated before, and others have also, the only difference between the 2A and 2B Hi-Pass section was the 2.7 ohm shunt resistor. The 2As use identical MW6510s for the stereo and dimensional drivers, where-as the 2Bs use an MW6503 for the stereo driver and an MW6511 for the dimensional driver. I can only surmise that the combined output of the two different sets of woofers is the main reason for the shunt resistor in the 2As. It was used to balance the output between the tweeter and woofers on the 2A, but was not needed for the 2B.
The bottom line is, 2As can be TL'd just like their younger sibling. This should apply to the 1986 CRS blade/blade as well.

[Mystery]

Nice!
So one resistor had to be removed, that's the only difference right?

[westmassguy]

Nice!
So one resistor had to be removed, that's the only difference right?

No, the resistor stays, that was the test