SDA2A RDO198 Upgrade??

[westmassguy]

This is very interesting. Was just wondering how much of an ordeal it would be to go "TL" on my 2Bs. If it is just a matter of swapping some caps, it may be something I can handle.

2Bs are easy, and hopefully my 2As will be as well

[westmassguy]

Copied from my other post:
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.

[doctorolds]

That is great, I guess that will be the route I take when I restore my 2A's. I think that I am also going to put some real wood veneer on them while I'm at it. Thanks again for the update.

[westmassguy]

That is great, I guess that will be the route I take when I restore my 2A's. I think that I am also going to put some real wood veneer on them while I'm at it. Thanks again for the update.

You're welcome doctorolds. My 2As sound absolutely amazing. Between the TL Mod, and the upgrades I did on the low-pass dimensional inductors and bypass caps.

[doctorolds]

I guess I will have to read over this post or your other to get all the info but I may PM you if I need a bit of help. I hope you are enjoying them.

[westmassguy]

I guess I will have to read over this post or your other to get all the info but I may PM you if I need a bit of help. I hope you are enjoying them.

doctorolds my other thread is here: http://www.polkaudio.com/forums/show...ished...Almost
I am enjoying them immensely, truely superb after the TL Mod, and the Bass work. Whether 2 channel or Home Theater, they do not disappoint. If you need and guidance don't hesitate.