Questions about stock 2.3TL Crossover

Dwightlud

I have a pair of 2.3TLs that I have had for many years. They rarely get any use because they are in the downstairs family room. I decided to fire them up the other day and thought they sounded like crap. Specifically there was very little high end. I pulled to the front covers and realized that the #1 tweeters in both speakers were fried. The overall sound was somewhat muddy, with very little clarity. So, I began an internet search for replacement tweeters and stumbled upon this site. I ordered a pair of 198s from Polk (I realize it might not be ideal to mix 198s with the 3000s). I then started reading this forum to educate myself on these speakers. Now I am thinking about the crossover upgrade, so today I pulled my crossovers and discovered some interesting things

First, it seems like Polk deviated quite a bit from the schematic with the cap values. The 16uF cap in the schematic is replaced by a 4.4uF and 4.2uF run in parallel on both of my crossovers. Same situation with the 16uF and 18uF caps. both have dual caps run in parallel that do not add up to the stated values in the schematics. does anyone have any insight on this?

Also there are two 750pF caps run in parallel with both the 8uF and 16uF caps. on one of my boards, one of these 750pF caps is missing. If you look closely, you can see that one lead of the 8uF cap is connected to the far side of the R2 location on the board. If you flip over the board and look at the tracings, it appears that this configuration is incorrect. In order for the 750pF cap to be in parallel with the 8uF cap, the 8uF cap should be connected to the near side of the R2 position on the board. Does this make sense or am I missing something?

I noticed that the Gimpod upgrade does not include the 750pF caps.
At any rate, I am looking forward to making the upgrade, and would not have even been aware of it if not for stumbling on this great forum.

zane77

There's tons of mods that you can do to those, welcome to the club, you can pick up a ton of information here

F1nut

The lack of high end is likely due to the polyswitches failing and therefore blocking any signal to all of the tweeters. The tweeters work as a progressive point source with the top tweeter being full range, the other two are frequency limited and will not sound like they put much out even when working properly.

What's really interesting is the crossover label. It should read 2.3TL/BR2200-C and I've never seen a label with "new" printed on it. Perhaps the "B" stood for buzzed.

First, it seems like Polk deviated quite a bit from the schematic with the cap values. The 16uF cap in the schematic is replaced by a 4.4uF and 4.2uF run in parallel on both of my crossovers. Same situation with the 16uF and 18uF caps. both have dual caps run in parallel that do not add up to the stated values in the schematics. does anyone have any insight on this?

Did you mean the 8uF was replaced by a 4.4uF and 4.2uF? That would be 8.6uF and within 10% tolerance.

Also there are two 750pF caps run in parallel with both the 8uF and 16uF caps. on one of my boards, one of these 750pF caps is missing.

Yep, someone had too much magic smoke in them building your crossovers.

If you look closely, you can see that one lead of the 8uF cap is connected to the far side of the R2 location on the board. If you flip over the board and look at the tracings, it appears that this configuration is incorrect. In order for the 750pF cap to be in parallel with the 8uF cap, the 8uF cap should be connected to the near side of the R2 position on the board. Does this make sense or am I missing something?

I noted the same thing on mine and another that I did for a member. That 750pF was doing nothing.

I noticed that the Gimpod upgrade does not include the 750pF caps.

That's correct. They are not needed when upgrading to superior film/foil caps.

Bubinga99

Hey guys,
I don't check in much, but happened across this thread. When I redid my crossovers they had the same 2200-B New labels on them (I'm the original owner):

Left x-over:



Right x-over:



Somewhere I also have the measured R, L, and C values from both crossovers before I rebuilt them.

Dwightlud

F1nut wrote: »

The lack of high end is likely due to the polyswitches failing and therefore blocking any signal to all of the tweeters. The tweeters work as a progressive point source with the top tweeter being full range, the other two are frequency limited and will not sound like they put much out even when working properly.

What's really interesting is the crossover label. It should read 2.3TL/BR2200-C and I've never seen a label with "new" printed on it. Perhaps the "B" stood for buzzed.



Did you mean the 8uF was replaced by a 4.4uF and 4.2uF? That would be 8.6uF and within 10% tolerance.

Yep, I meant to say 8uF.

Yep, someone had too much magic smoke in them building your crossovers.



I noted the same thing on mine and another that I did for a member. That 750pF was doing nothing.



That's correct. They are not needed when upgrading to superior film/foil caps.

Thanks for the information. Helps a lot.

F1nut

I have to think both of you have very early 2.3TL's. Hence the "B" with 2.3 and "new" to distinguish them from the original 2.3's because Polk had not assigned the TL to them yet.

Dwightlud

F1nut wrote: »

I have to think both of you have very early 2.3TL's. Hence the "B" with 2.3 and "new" to distinguish them from the original 2.3's because Polk had not assigned the TL to them yet.

I noticed that a number of the other components (the tweeters for one) have dates stamped on them that fall between July and August of 1989. I'm wondering if that would make them part of the 1990 model year.

F1nut

They came out in 1989 and the later date stamp would be the one closest to when yours were built.

drumminman

Re: the tweeters, I would not mix RD-0198's with SL 3000's. The former are superior and completely worth the expense to replace all 6 IMO. They're smoother and yet more detailed with better imaging.

Oh, and welcome to the forum!

Bubinga99

F1nut wrote: »

I have to think both of you have very early 2.3TL's. Hence the "B" with 2.3 and "new" to distinguish them from the original 2.3's because Polk had not assigned the TL to them yet.

Very interesting! My S/N's are in the 4800 range. I used to have a second pair which were in the S/N 5300 range and they also had the "B" and "New" on the crossover sticker. So the change must have been after S/N 5300. Of course, we're assuming that "C" came after "B" but who knows. Numbering schemes are not always logical and the B and C could designate something else.

I know my measured values were a bit different than the 2.3TL schematic available here on the forum, and in particlar one inductor on mine measured about 40% less than the schematic value and that was the case for all 4 of the 2.3TL's I had at the time so I don't think it was a fluke.

What S/N range are yours in?

Dwightlud

Bubinga99 wrote: »

Very interesting! My S/N's are in the 4800 range. I used to have a second pair which were in the S/N 5300 range and they also had the "B" and "New" on the crossover sticker. So the change must have been after S/N 5300. Of course, we're assuming that "C" came after "B" but who knows. Numbering schemes are not always logical and the B and C could designate something else.

I know my measured values were a bit different than the 2.3TL schematic available here on the forum, and in particlar one inductor on mine measured about 40% less than the schematic value and that was the case for all 4 of the 2.3TL's I had at the time so I don't think it was a fluke.

What S/N range are yours in?

Mine are R4335 and L4345

F1nut

Very interesting! My S/N's are in the 4800 range. I used to have a second pair which were in the S/N 5300 range and they also had the "B" and "New" on the crossover sticker. So the change must have been after S/N 5300. Of course, we're assuming that "C" came after "B" but who knows. Numbering schemes are not always logical and the B and C could designate something else.

Interesting indeed. The crossover ID provided by Polk does not list a BR2200-B for the 2.3TL's. It goes from BE2200-A for the 2.3's to BR2200-C for the TL's.

I know my measured values were a bit different than the 2.3TL schematic available here on the forum, and in particlar one inductor on mine measured about 40% less than the schematic value and that was the case for all 4 of the 2.3TL's I had at the time so I don't think it was a fluke.

Do you remember which inductor that was?

What S/N range are yours in?

In the 5480's, dated May 1992.

Bubinga99

The inductor that was different was the one listed in the schematic as 0.30mH (in the tweeter crossover network). My measured value was 0.18mH.

Here are some plots of the response, done with LSPcad. The first one is the response of the tweeter crossover network with the standard schematic values: (green is total response; orange is the top tweeter, red is middle, and blue is the lower tweeter)



and this next one is the response using the measured .18mH value instead of .3mH:



You can see from the graph that the .18mH inductor gives the upper tweeter (orange curve) a slightly flatter response and slightly higher output. It also slightly shifts the knee frequency up from about 2kHz to about 2.5KHz.

When I rebuilt my crossovers, I did some experimenting and changed some R's and C's very slightly, with the resulting response curve as shown below:




With these changes, (and keeping that inductor at .18mH) the total response curve for the tweeter crossover network (in green) and the upper tweeter (in orange) are flat to within 1dB. It's a fairly subtle difference from the schematic values, but I ended up liking it with my setup, so I left it and the experiment ended with that.

There is also a subtle change/improvement in the impedance plot. The first plot below is the tweeter crossover network using the schematic values except for changing the .3mH inductor to .18mH since that's what my speakers had to work with, and the second plot is using the values I changed when I rebuilt the crossover.








Comparing the two, you can see that with my changes the crossover network presents a more uniform/smooth load compared to the schematic values, and also has a slightly higher minimum impedance. I don't think most decent amps would have much trouble driving either of them though.

PolkieMan

I guess you pulled all of the MW drivers and made sure that they are 6510.
You know of the SDA Handbook, lots of info. In there it says the the 198 do not
differ that much from the 3000 tweeters so what I did was replace them two at a time
over the course of 3 months for all 6.

vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf‎

F1nut

I need to correct a few things in my last post. My crossovers are marked BE2200-C and are dated 6/20/92. Judging from all the other crossovers listed by Polk the BR for the 2.3TL's was a typo and should be BE.

PolkieMan

my old 1990 2.3tls x-overs

c

F1nut

PolkieMan wrote: »

In there it says the the 198 do not
differ that much from the 3000 tweeters so what I did was replace them two at a time
over the course of 3 months for all 6.

They differ enough that after I installed one new RD0198-1 per cabinet in the top position the next day I ordered the rest. It was obvious that the RD0198-1 was a much better tweeter.

F1nut

Thanks Bubinga99, I'll have to check mine the next time I pull the crossovers. The irony is the next time I pull them will be to change the stock inductors for the Jantzen's I bought.

Bubinga99

F1nut wrote: »

...the next time I pull them will be to change the stock inductors for the Jantzen's I bought.

Oh, cool. A few years back when I was a more frequent forum reader, most people stayed away from inductor swaps. Has that changed in the interim, and I guess folks have tried it and liked it?

Are you going to change them all with the same values (including DCR)? Or just some of them?

F1nut

Yes times have changed, people ran out of things to tweak in their SDA's, so inductors have become the latest victims.

All inductors with the same mH values, but lower DCR.

VR3

Hey Jesse,
The DCR on the inductors are identical to stock, FWIW

F1nut

Ok thanks, obviously I thought they were less.

headrott

The Jantzen inductors sound great. The best place I found for the big 16mH inductor so far is on the lowest corssbeam all the way against the back wall of the speaker. I still need to move it around up there to make sure. But Trey, IMO this position is better than directly behind the PR. Sorry for the thread derail, but I hope this helps the OP too.

PolkieMan

I did it over 3 months two at a time so it was not noticed by the boss :cheesygrin:

F1nut wrote: »

They differ enough that after I installed one new RD0198-1 per cabinet in the top position the next day I ordered the rest. It was obvious that the RD0198-1 was a much better tweeter.

PolkieMan

Did you notice a change in the bass? How much did it lower your ohms?

headrott wrote: »

The Jantzen inductors sound great. The best place I found for the big 16mH inductor so far is on the lowest corssbeam all the way against the back wall of the speaker. I still need to move it around up there to make sure. But Trey, IMO this position is better than directly behind the PR. Sorry for the thread derail, but I hope this helps the OP too.

dcoil

VR3 wrote: »

Hey Jesse,
The DCR on the inductors are identical to stock, FWIW

I think the DCR on the HF and LF are all the same as stock, except for the large 16mH inductor. Ray stated that the 14AWG NorthCreek had a lower DCR, and that the larger 10 AWG Solen was even lower if I remember correctly. I liked the improvement going to the NorthCreeks on my SRS's so much that I'm now thinking about going to the larger Solens.