Differences in the large SRS models, and upgrade tweeters?

John in MA

Something I've been wondering about for years. There's been a lot of discussion on this subject in the past, but each thread I read had varying opinions or information stated as fact. I don't have an SDA Compendium so maybe I'm just out of the loop and missed the memo.

After searching, reading, and looking through diagrams and old technical descriptions I tried to mentally sort all this out. Not counting transitionals or those lovable Polk "oops" models that pop up now and then. Am I close with these descriptions?

Original SDA-SRS model
-Large crossover
-Same main/SDA drivers
-Braced cabinet
-SL2000 tweeters(?)
-14-screw crossover panel(?)
-Blade-blade interconnect

SDA-SRS 1.2
-Small PCB crossover
-Different driver rows
-Cut/molded cabinet structure
-9-screw panel(?)
-Blade/pin interconnect
-Available bass brace and AI-1 interconnect

SDA-SRS 1.2TL
-Altered values in high range crossover section
-SL3000 tweeters


That brings me to the second part of my question: As the basic design of the 1.2 appears to have been just changed to allow for the trilaminate tweeters in the 1.2TL, how do the silk dome replacements stack up against each other and the old tweeters they're replacing?

ie: Do 194 and 198 domes provide sonically similar (to each other) replacements that differ mainly in what driving circuitry they mate to? Or does the 198 have an improved sound over the 194, similar to how the SL3000 smoothed the SL2000's peaky performance?

And taking that into account, if one were to get silk domes for a SL2000-equipped 1.2, would there be any point to changing the crossover to TL specs and using the 198s?

Ricardo

You'll have to wait. The person that has the answer to all of this is out for a week.

read-alot

Ricardo wrote: »

You'll have to wait. The person that has the answer to all of this is out for a week.

I'd say Raife would be the one to ping with this question.

He did write the book.

DarqueKnight

My answers are in red.

John in MA wrote: »

Something I've been wondering about for years. There's been a lot of discussion on this subject in the past, but each thread I read had varying opinions or information stated as fact. I don't have an SDA Compendium so maybe I'm just out of the loop and missed the memo.

After searching, reading, and looking through diagrams and old technical descriptions I tried to mentally sort all this out. Not counting transitionals or those lovable Polk "oops" models that pop up now and then. Am I close with these descriptions?

Original SDA-SRS model
-Large crossover
-Same main/SDA drivers
-Braced cabinet
-SL2000 tweeters(?)
-14-screw crossover panel(?)
-Blade-blade interconnect

SDA-SRS 1.2
-Small PCB crossover
-Different driver rows
-Cut/molded cabinet structure
-9-screw panel(?)Some of the early 1.2's used the 14 bolt XO panel
-Blade/pin interconnect
-Available bass brace and AI-1 interconnect
-Monocoque cabinet stucture for reduced bass resonance
-Wood veneer over MDF end caps (SRS had laminated solid wood end caps-which were prone to cracking/splitting)

SDA-SRS 1.2TL
-Altered values in high range crossover section
-SL3000 tweeters
-Enhanced "Point Source" driver technology


That brings me to the second part of my question: As the basic design of the 1.2 appears to have been just changed to allow for the trilaminate tweeters in the 1.2TL, how do the silk dome replacements stack up against each other and the old tweeters they're replacing?

ie: Do 194 and 198 domes provide sonically similar (to each other) replacements that differ mainly in what driving circuitry they mate to? Or does the 198 have an improved sound over the 194, similar to how the SL3000 smoothed the SL2000's peaky performance?

The SL3000 offered flatter, more accurate response than the SL2000. The RD0194 sounds closer to the sound of the RD0198 than the SL2000 does to the SL3000. I asked for frequency response charts of the RD0 tweeters, but Polk declined due to proprietary concerns.

I do not say that one tweeter is "better" than the other as the sound of the tweeters is a matter of taste. I prefer the SL3000/RD0198 over the SL2000/RD0194 and I prefer the sound of the RD0's over the SL's.

In post #29 of the Improvements to the SDA SRS thread, I discuss sonic differences between my SRS and SRS 1.2TL speakers modified with RD0 tweeters (and other goodies:)).


And taking that into account, if one were to get silk domes for a SL2000-equipped 1.2, would there be any point to changing the crossover to TL specs and using the 198s?

At one time Polk offered a 1.2 to 1.2TL conversion kit, but that kit included new crossovers as well as new tweeters. From looking at the schematics of the SRS 1.2 and SRS 1.2TL, converting a 1.2 crossover to would not be a trivial undertaking, but you could do it. Again, whether a 1.2 to 1.2TL conversion would be beneficial to you depends on your listening preferences. As you go from SRS to SRS 1.2 to SRS 1.2TL, you get flatter more accurate response and more image stability.

Some people prefer the bass and treble emphasis of the original SRS and consider the 1.2 and 1.2TL "dull" sounding by comparison. Non-audiophile visitors to my home always ask me why do I even have the 1.2TL's because the SRS's "sound so much better". They understand after they sit and listen and I point certain things out to them.;)

John in MA

Thank you for the information, I appreciate it.

I had read your "Improvement" thread, but I was more curious about upgraded 1.2 vs. 1.2TL since there's little difference between the two, compared to your original SRS vs. 1.2TL test.

Do you feel that there'd be noticable difference between the 194 and 198 when the host speaker is taken out of the picture?

I looked at the crossover schematics and it doesn't look terribly hard to convert to TL spec. Some changed components and a couple of rerouted traces. I believe the largest difference in schematics (of the tweeter grounds) is due more to drafing notation than actual layout.

DarqueKnight

John in MA wrote: »

Thank you for the information, I appreciate it.

I had read your "Improvement" thread, but I was more curious about upgraded 1.2 vs. 1.2TL since there's little difference between the two, compared to your original SRS vs. 1.2TL test.

I have never had an opportunity to compare either stock or upgraded 1.2's to 1.2TL's. I do know that small changes can make a huge difference in a speaker's sound. For example, adding a 5.8uF capacitor to the crossover and changing the tweeters of the CRS+ from RD0194's to RD0198's made a dramatic difference (improvement) in the sound.

John in MA wrote: »

Do you feel that there'd be noticable difference between the 194 and 198 when the host speaker is taken out of the picture?

I am not sure I understand your question. The 194 and 198 are very different tweeters, so they are going to sound different. I cannot quantify how big of a difference or improvement you might attain. Depending on your listening preferences, you might not like the change at all. All of the SDA mods I have done, with the exception of changing binding posts, produced very noticeable improvements in sound. Listed in order of degree of improvement they are:

1. Crossover modification (changing resistors and capacitors).
2. Tweeter changes.
3. Bypass or remove tweeter protection polyswitch.
4. Replace stock SDA cable with heavy gauge cable.
5. Replace stock grille cloth with thinner cloth.

John in MA wrote: »

I looked at the crossover schematics and it doesn't look terribly hard to convert to TL spec. Some changed components and a couple of rerouted traces. I believe the largest difference in schematics (of the tweeter grounds) is due more to drafing notation than actual layout.

OK. Careful experimentation can be a good thing. Let us know how your mod project turns out.

John in MA

Thanks again, this is all very interesting. In what ways are the two silk dome tweeters different? I get the impression I've been operating under incorrect ideas (that the two are essentially similar, just designed to do their function with different crossovers.)

I guess what I was wondering is that once you remove the SL2000/SL3000 contrast, do the silk domes designed to replace them offer individual advantages rather than just upgrade both previous tweeters to the same new standard? And do the crossover changes made to suit the 3000's superior (to the 2000) attributes provide any unique advantage (over an RD0-upgraded, previously 2000 system) once there's an RD0 replacing the 3000?

I don't have any projects in the works. This was more to satisfy some practical curiosity than anything else. If I ever get a chance to try something like that I'll certainly involve the forum.