2B TL mod, finally

gmcman

With a little persuasion, I waited for Gimpod's boards and very happy I did.

I asked a couple in PM but thought I would get a general consesnus before I started soldering. I have a .5 ohm Mills and the 2.7 ohm...not the .22ohm. Has anyone found the .5 to be too dull or muted or should I wait or go with the lower value?

inspiredsports

In my specific situation, my 1987 blade/blade TL'd 2B's with all Sonicap capacitors and Mills resistors produces the flattest measured response curve with a .5 ohm Mills resistor in place of the removed factory (RDE050A) polyswitch. Your mileage may vary.

This helpful thread speaks to the several different polyswitches (each with different resistance ranges) that Polk used . . .

http://www.polkaudio.com/forums/showthread.php?73796

NOTE: some highly experienced Polkies suggest simply using a 3.2 ohm instead of a 2.7 + .5 as fewer components/connections theoretically reduce circuit path noise.

Conradicles

I used a .5 ohm mills to replace the polyswitch and loved the results...

Toolfan66

Conradicles wrote: »

I used a .5 ohm mills to replace the polyswitch and loved the results...

Me as well..

quadzilla

I hated the .5. Sounded like someone turned the treble knob all the way down, threw a heavy blanket over the speakers, however you want to put it. I find a range of .1-.2 to be best. And even .2 sounds a bit dull to me. I'm using .12 ohm in my 2.3s right now, and find that to be excellent. I might think about taking it up to .15 or down to .1, depending on how they sound after they break in.

Face

I would say the associated gear and room will determine if you need a resistor to replace the polyswitch or not, or if you should deviate from the recommended 2.7ohm resistor. For the 2BTL a single 3.2 does make more sense than two separate resistors. I used a 3.0ohm and was happy with the results.

gmcman

Thanks for the input, I suppose I will set it up with just the 2.7 to start and after some hours of break-in will go from there. I will add the .5 to the circuit after the break-in and see how much it attenuates the highs.

Just thinking that if I do that I may be disappointed after I get used to the highs...dunno.

F1nut

Start with it in, then after a month or so take it out. It's often easier to hear changes that way. I like the .5 ohm myself.

audiocr381ve

I have a lot of experience with this and my 2BTL's. I've taken them in and out numerous times. The times that I did have a resistor in, I was using a .5 ohm Mills. I felt like it was to much, but not at all bad sounding. Now I have a .47 ohm Mundorf in and I may try and use a lower value in the future, but for now it sounds pretty good to me.

audiocr381ve

Face wrote: »

I would say the associated gear and room will determine if you need a resistor to replace the polyswitch or not, or if you should deviate from the recommended 2.7ohm resistor. For the 2BTL a single 3.2 does make more sense than two separate resistors. I used a 3.0ohm and was happy with the results.

Still want to know how to do this on a 2B crossover

headrott

As Face said, gear and the room will have a big affect on the sound of using the resistor in place of the polyswitch. I used a .5 ohm mills in my 2BTL's and found it to sound very good. I have an Aragon 8008bb amp that can be a bit forward on the high end though. Although the signal upstream can have an affect on the sound coming from the Aragon as well. What gear are you using with the 2BTL's?

Greg

Stew

I tried several different values from 0.22 to 1.0 and ended up with the 0.5 ohm that F1 recommended to start with. It was the only one that sounded right to me. I've gone through a few gear changes since and still very happy with the 0.5. YMMV.

gmcman

Thanks again, I did go with the .5. One down, one to go.

Someone sure was trigger happy with the hot glue gun, or I would have had both done by now. :cool:

MillerLiteScott

I found the .5 resistor to be a little to much in my system and room. What bothered me the most with the .5 resistor was the upper bass and drums lacked the detail I was looking for moreso than the upper trble range. this may be room dependent though. With a jumper in it's place I felt it was to bright and was unbalanced. I ended up with a .22 resistor and am very pleased with the balance of the speaker in my room.

inspiredsports

Schematics show early (1987) blade/blade and pin/blade 2B's used the RDE050A polyswitch (.50 to .77 ohm), and the 1989 pin/blade models used the RDE090A (.25 - .40 ohm) [resistance values according to post #1 http://www.polkaudio.com/forums/showthread.php?73796].

Just a theory, but only one side of the SDA interconnect wire is connected in blade/blade models, and both are connected in the pin/blade models. Maybe they found the additional resistance of the additional length of interconnect in pin/blade models allowed for a lower resistance poly.

Aditionally, resistance values of custom SDA interconnect cables might come into play.

This could account for some of the variability folks are experiencing.

My guess is approx. .50 ohm works best in blade/blade models, and approx. .25 ohm in pin/blade models.

quadzilla

I would basically agree with the above, except that again, it's very dependent on tastes, room, and equipment. My system tends towards warm any way, so the ranges I use suit me and my tastes. I'm a detail freak, so I use just enough to take the sibilant edge off, but not enough to mask any detail in the treble range.

inspiredsports

quadzilla wrote: »

I would basically agree with the above, except that again, it's very dependent on tastes, room, and equipment. My system tends towards warm any way, so the ranges I use suit me and my tastes. I'm a detail freak, so I use just enough to take the sibilant edge off, but not enough to mask any detail in the treble range.

I know I'm posting very technically, but I think that's a great way to get started with modifications.

Your post speaks to the "measures good, sounds bad" effect that sometimes doesn't account for the real listening environment.

The other reality is that as your hearing ages, "hotter" treble makes up for what nature is taking away. Many older listeners may not realize a flat response can sound dull to their de-tuned hearing ability.

quadzilla

inspiredsports wrote: »

I know I'm posting very technically, but I think that's a great way to get started with modifications.

Your post speaks to the "measures good, sounds bad" effect that sometimes doesn't account for the real listening environment.

The other reality is that as your hearing ages, "hotter" treble makes up for what nature is taking away. Many older listeners may not realize a flat response can sound dull to their de-tuned hearing ability.

Yes, but... When I run the calibration in my HT system, I get flat +/-a few db up through 20 KHz, and a full frequency analysis on that setup shows that the response is, indeed, pretty flat out past 20 KHz. My last hearing check also showed that I'm still pretty flat out to 14 KHz. So again, the right resistor will largely depend on taste, room, and other equipment.

inspiredsports

quadzilla wrote: »

I hated the .5. Sounded like someone turned the treble knob all the way down, threw a heavy blanket over the speakers, however you want to put it. I find a range of .1-.2 to be best. And even .2 sounds a bit dull to me. I'm using .12 ohm in my 2.3s right now, and find that to be excellent. I might think about taking it up to .15 or down to .1, depending on how they sound after they break in.

You've got me curious now;
-- Do you have blade/blade of pin/blade SDA's?
-- Do you know if they are '87-88's or 89's?
-- Do you have a modded SDA interconnect cable?

audiocr381ve

Face wrote: »

I would say the associated gear and room will determine if you need a resistor to replace the polyswitch or not, or if you should deviate from the recommended 2.7ohm resistor. For the 2BTL a single 3.2 does make more sense than two separate resistors. I used a 3.0ohm and was happy with the results.

I was thinking about this. To accomplish it all it would really take is replacing the the 2.7 ohm resistor in it's current position with say a 3.0ohm and jumping the original polyswitch position right (where the .5ohm should go)?

quadzilla

inspiredsports wrote: »

You've got me curious now;
-- Do you have blade/blade of pin/blade SDA's?
-- Do you know if they are '87-88's or 89's?
-- Do you have a modded SDA interconnect cable?

P/B, both pair.
CRS+ TL'ed to 4.1 are '89, the 2.3TLs are '92 (4/24/92 xover assm date).
Using a stock AI-1.

Face

audiocr381ve wrote: »

I was thinking about this. To accomplish it all it would really take is replacing the the 2.7 ohm resistor in it's current position with say a 3.0ohm and jumping the original polyswitch position right (where the .5ohm should go)?

That's one way to go about it, yes.

audiocr381ve

Face wrote: »

That's one way to go about it, yes.

Nice, that's a lot easier than I thought man!

gmcman

Well....I can say for now the .5 definately isn't dull...

I went ahead and Dynamatted the PR, used some 1/2 x 3/16 thick foam weatherstripping around the mids and cut a gasket out of a piece of 1/16" anti-slip mat for the tweeter. Needless to say the bass has improved noticeably and surely from a combination of the caps and the treatment.

Granted I only have 2 hours on the mod but the highs are still there but much smoother, much more detail without the harshness.

Have switched over to TV for the evening and can say the highs are bright....but not fatiguing so time will tell.

inspiredsports

quadzilla wrote: »

P/B, both pair.
CRS+ TL'ed to 4.1 are '89, the 2.3TLs are '92 (4/24/92 xover assm date).
Using a stock AI-1.

Thanks. So far that would support my .25 for pin/blade and .50 for blade/blade theory.

I'm curious as to what others have experienced with blade/blade versus pin/blade mods in regard to resistor value that works best when removing polyswitch.

PreCd

I went with a .27 Mills resistor in place of the poly switch. It sounds very good. I would like to go back and put the .5 Mills in there to compare but there is no need to do it as the .27 Mills is doing good.

inspiredsports wrote: »

Thanks. So far that would support my .25 for pin/blade and .50 for blade/blade theory.

I'm curious as to what others have experienced with blade/blade versus pin/blade mods in regard to resistor value that works best when removing polyswitch.

gmcman

quadzilla wrote: »

P/B, both pair.
CRS+ TL'ed to 4.1 are '89, the 2.3TLs are '92 (4/24/92 xover assm date).
Using a stock AI-1.

However this is not the 2B, granted the .5 should perform similiar but for sake of arguement...would this have the same effect especially with multiple tweters in the 2.3?

quadzilla

gmcman wrote: »

However this is not the 2B, granted the .5 should perform similiar but for sake of arguement...would this have the same effect especially with multiple tweters in the 2.3?

No, the 2B is not a CRS+/4.TL, but it is the same crossover and drivers, so they should sound very similar.

Yes, the polyswitch/resistors work the same in the 2.3TL. When I first got them, they lacked a bit of sparkle on the top end, so I replaced the polyswitch with a .1 ohm resistor. But since the upgrade was to use RDO-198s, I went slightly higher with a .12 ohm resistor. If, after the break in, they seem a bit bright, I'll put something larger in there. When I did my 4.1s, I just had a jumper in initially, but after break-in, I decided it was too bright. Tried a .5, and again, it was horrible. Went to a .2, and it was ok, but still didn't have that sparkle on the top end that I know my gear can produce. Went to a .1, and voila. And that's for my 4.1 TLs. The 2.3TLs, well, the jury is still out since they've got less than 30 hours on them now, and they need at least 200 to settle down.

quadzilla

gmcman wrote: »

However this is not the 2B, granted the .5 should perform similiar but for sake of arguement...would this have the same effect especially with multiple tweters in the 2.3?

No, the 2B is not a CRS+/4.TL, but it is the same crossover and drivers, so they should sound very similar.

Yes, the polyswitch/resistors work the same in the 2.3TL. When I first got them, they lacked a bit of sparkle on the top end, so I replaced the polyswitch with a .1 ohm resistor. But since the upgrade was to use RDO-198s, I went slightly higher with a .12 ohm resistor. If, after the break in, they seem a bit bright, I'll put something larger in there. When I did my 4.1s, I just had a jumper in initially, but after break-in, I decided it was too bright. Tried a .5, and again, it was horrible. Went to a .2, and it was ok, but still didn't have that sparkle on the top end that I know my gear can produce. Went to a .1, and voila. And that's for my 4.1 TLs. The 2.3TLs, well, the jury is still out since they've got less than 30 hours on them now, and they need at least 200 to settle down. I do recall basing my decision on the specs listed for the RXE135 from the thread inspired linked to earlier, but decided to go just a tad hotter initially due to he increased smoothness and extension of the 198s over the SL3000s (.12 as opposed .16-.17). And because I had like the .1 with the SL3000, I figured .12 with the 198s was a good place to start.

F1nut

One man's sparkle is another man's ear bleed.

quadzilla

har. dee. har. har. But then, my dad always enjoyed his AM radio with the tone knob turned all the way down. Maybe you point five guys are like that? :razz: