SDA SRS 2's

lbcgav

I picked these up yesterday. They sound pretty darn good as they are and I can't wait to upgrade them.

So, what exactly is the verdict on the TL mod with these? I know it appears to be a point of contention with some members here.



The SRS 2's dwarf the SDA 2A's:

westmassguy

There isn't one, period.

Mike Reeter

Congrats on your SRS 2's, they appear to be in great condition.

I will let others comment on the TL upgrades, in the meantime enjoy them as they are!

lbcgav

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

westmassguy

lbcgav wrote: »

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

I say changing Caps in a complex network like the lower tweeter has in the 1C is a fools errand. Without knowing the overall frequency response of the RDO-198s, their T/S parameters, you're completely in the dark. The 198s are not meant to be used in conjunction with the 194s either, which others are doing. Some pretty smart people, with measuring equipment, computer plotting programs, extensive listening tests etc., designed the progressive point source used in the 1Cs and SRS 2s. You don't fix what isn't broken.

lbcgav

westmassguy wrote: »

lbcgav wrote: »

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

I say changing Caps in a complex network like the lower tweeter has in the 1C is a fools errand. Without knowing the overall frequency response of the RDO-198s, their T/S parameters, you're completely in the dark. The 198s are not meant to be used in conjunction with the 194s either, which others are doing. Some pretty smart people, with measuring equipment, computer plotting programs, extensive listening tests etc., designed the progressive point source used in the 1Cs and SRS 2s. You don't fix what isn't broken.

Thanks for the reply.

lbcgav

Has anyone else done the mod and been pleased with it? I'd be interested to hear any other opinions.

Schurkey

lbcgav wrote: »

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

WHICH VERSION do you have???
The inspiredsports mod was based on the SRS 2 blade/blade (earlier version, similar to SDA 1B)

It's my intention to try this on my SRS 2 pin/blade. Maybe it works well...maybe not. The SRS 2 pin/blade is similar to the SDA 1C in regards to tweeter crossover.

lbcgav

Schurkey wrote: »

lbcgav wrote: »

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

WHICH VERSION do you have???
The inspiredsports mod was based on the SRS 2 blade/blade (earlier version, similar to SDA 1B)

It's my intention to try this on my SRS 2 pin/blade. Maybe it works well...maybe not. The SRS 2 pin/blade is similar to the SDA 1C in regards to tweeter crossover.

Blade-blade version.

F1nut

westmassguy wrote: »

I say changing Caps in a complex network like the lower tweeter has in the 1C is a fools errand. Without knowing the overall frequency response of the RDO-198s, their T/S parameters, you're completely in the dark. The 198s are not meant to be used in conjunction with the 194s either, which others are doing. Some pretty smart people, with measuring equipment, computer plotting programs, extensive listening tests etc., designed the progressive point source used in the 1Cs and SRS 2s. You don't fix what isn't broken.

\

I agree 100%.

lbcgav

Schurkey wrote: »

lbcgav wrote: »

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

WHICH VERSION do you have???
The inspiredsports mod was based on the SRS 2 blade/blade (earlier version, similar to SDA 1B)

It's my intention to try this on my SRS 2 pin/blade. Maybe it works well...maybe not. The SRS 2 pin/blade is similar to the SDA 1C in regards to tweeter crossover.

So do westmassguy's comments only apply to the pin/blade version? He did mention the SDA 1C and not the 1b, which, from what I gather shares the same schematic as my SDA SRS2 4 ohm version.

Nightfall

I'd buy some RDO-194's and forget about the 198's.

westmassguy

lbcgav wrote: »

Schurkey wrote: »

lbcgav wrote: »

westmassguy wrote: »

There isn't one, period.

So what do you say about inspiredsports mod of replacing the 4.4uf cap with a 5.8uf cap and throw in the 198 tweeters? It appears others have done the same mod and been happy with it. Am I missing something?

WHICH VERSION do you have???
The inspiredsports mod was based on the SRS 2 blade/blade (earlier version, similar to SDA 1B)

It's my intention to try this on my SRS 2 pin/blade. Maybe it works well...maybe not. The SRS 2 pin/blade is similar to the SDA 1C in regards to tweeter crossover.

So do westmassguy's comments only apply to the pin/blade version? He did mention the SDA 1C and not the 1b, which, from what I gather shares the same schematic as my SDA SRS2 4 ohm version.

No. My comments apply to the 1B and 1C, as well as the 3rd and 4th generation SRS 2s.

Msabot1

If it ain't broke..don't fix it...heck dude,those look brand new!...

helipilotdoug

I have the blade/blade SRS 2 speakers and did the mod inspiredsports pioneered. I am very happy with the results and can recommend doing it. If you plan to do this mod, the below thread will help you understand what to expect. It's kind of long, but deserves reading the whole thing to understand how this mod came about. http://forum.polkaudio.com/discussion/74946/sda-srs-2-crossover-parts-list/p1

One question for the nay sayers on the inspiredsports mod of the blade/blade SRS 2. Have you actually heard these speakers after the mod? If not, you might want to find someone who has done it, and get your ears on them. Listening might just change your tune!

westmassguy

helipilotdoug wrote: »

I have the blade/blade SRS 2 speakers and did the mod inspiredsports pioneered. I am very happy with the results and can recommend doing it. If you plan to do this mod, the below thread will help you understand what to expect. It's kind of long, but deserves reading the whole thing to understand how this mod came about. http://forum.polkaudio.com/discussion/74946/sda-srs-2-crossover-parts-list/p1

One question for the nay sayers on the inspiredsports mod of the blade/blade SRS 2. Have you actually heard these speakers after the mod? If not, you might want to find someone who has done it, and get your ears on them. Listening might just change your tune!

Good read. The only Mod I was aware of, was replacing the 4uf cap with a 5.8uf, which only affects the lower tweeter.
This Mod makes sense since it's adding a contour network, which is similar to the CRS+, 2B, and Monitor 5 SL3000 Mod.
I stand corrected, since MP himself endorsed it.
This would not apply to the 1C or 4th generation SRS 2 though, as there's no resistor upstream from the 12uf cap.

oldrocker

Picking up a set of SDA 2 on Thursday.

An advanced warning of the dumbest questions ever asked is coming...

westmassguy

Just thinking out loud. On the 4th generation 1C and SRS 2, there are two 7.5 ohm resistors directly upstream from the tweeters. If we reduced the value to 4.7 ohm for example, and added a 2.7 ohm resistor, shunted with the 5.8uf cap in place of the jumper that's before the Polyswitch, would that accomplish the same thing?

Schurkey

oldrocker wrote: »

Picking up a set of SDA 2 on Thursday.

An advanced warning of the dumbest questions ever asked is coming...

Be aware that the SDA 2 is a totally different design than either version of the SDA SRS 2 .

gimpod

Why is it every time someone post about SDA SRS 2's someone always post a link to the so-called TL mod that was done by inspiredsports that was done on an early pair of SDA SRS 2 (1986) blade/blade version that no matter how times I read it, IMO it still doesn't explain what you do to the other tweeter to get it to work right regardless of the version (pin/blade or blade/blade) same go's for the 1Bs and 1Cs.

If it ain't broke don't fix it. Just get the RDO-194s and don't look back, you'll be happy.

tonyb

They do it just to knock your nuts around Tony. lol

Someone has to yank your chain every so often, keep you sharp.

westmassguy

Actually, to follow up on my last post, I had a conversation with Ken, who was mentioned in the inspiredsports thread. I asked him to look at this thread, and also tossed a few scenarios at him for modifying the 1C and 4th generation SRS 2. We came up with a viable solution for them.

westmassguy

gimpod wrote: »

Why is it every time someone post about SDA SRS 2's someone always post a link to the so-called TL mod that was done by inspiredsports that was done on an early pair of SDA SRS 2 (1986) blade/blade version that no matter how times I read it, IMO it still doesn't explain what you do to the other tweeter to get it to work right regardless of the version (pin/blade or blade/blade) same go's for the 1Bs and 1Cs.

If it ain't broke don't fix it. Just get the RDO-194s and don't look back, you'll be happy.

I would agree with you Tony, however I read and re-read the thread. I understand what they did.
The lower Tweeter, T2 is fed through a band pass filter. The SL3000 and RDO-198 have a rising impedance curve, so the TL mod, which is a contour circuit added to existing crossovers, compensates for this. T2 is bandwidth limited, and rolls off before the contour circuit comes in to play. Only the upper Tweeter, T1 needs the contour circuit.

gimpod

David, Do the RDO-194 & RDO-198 have the the same impedance and matching impedance curves and other parameters (think not). As this info is not published I would think designing a crossover (don't forget about balancing the HP with the LP and working out any phasing issues) would be difficult at best unless you've got the test gear and time.

IMO: just not worth it.

oldrocker

Schurkey wrote: »

oldrocker wrote: »

Picking up a set of SDA 2 on Thursday.

An advanced warning of the dumbest questions ever asked is coming...

Be aware that the SDA 2 is a totally different design than either version of the SDA SRS 2 .

The back of them say SDA 2, is blade/pin.
Kind of getting worried already from what I've read.

But since the wife bid/bought them, I have to smile...

F1nut

oldrocker wrote: »

The back of them say SDA 2, is blade/pin.

Those are going to be the SDA 2B, no SRS. You will be able to upgrade them to 2BTL's with ease.

oldrocker

Thank you very much.

Truth is, I'm not 100% sure what she bought, she showed me that rear picture and it just says SDA 2.

I hate being the "dunce" of the room but someone has to wear the hat

Will know more Thurs.

EndersShadow

oldrocker wrote: »

Thank you very much.

Truth is, I'm not 100% sure what she bought, she showed me that rear picture and it just says SDA 2.

I hate being the "dunce" of the room but someone has to wear the hat

Will know more Thurs.

Trust me, your not the "dunce" that comes to mind when most of us think that....

....

Now enjoy.

westmassguy

gimpod wrote: »

David, Do the RDO-194 & RDO-198 have the the same impedance and matching impedance curves and other parameters (think not). As this info is not published I would think designing a crossover (don't forget about balancing the HP with the LP and working out any phasing issues) would be difficult at best unless you've got the test gear and time.

IMO: just not worth it.

No I don't have specifics on either RDO, however MP does, and Ken was involved in that conversation. The RDO-198 has a rising impedance which results in a slight downward slope in frequency response. This is compensated for by the contour circuit. We add that to all single Tweeter SDAs and some Monitors for the TL mod.
The Lower Tweeter, which should also be replaced with the 198, doesn't require the contour circuit, because its output is filtered through a band-pass filter.
When Ken and I discussed the 1C and SRS 2 pin/blade yesterday, a similar contour circuit could be added to those models as well.

I don't have a 1C or 4th generation SRS 2 to test it on.

Schurkey

gimpod wrote: »

Why is it every time someone post about SDA SRS 2's someone always post a link to the so-called TL mod that was done by inspiredsports that was done on an early pair of SDA SRS 2 (1986) blade/blade version that no matter how times I read it, IMO it still doesn't explain what you do to the other tweeter to get it to work right regardless of the version (pin/blade or blade/blade) same go's for the 1Bs and 1Cs.

If it ain't broke don't fix it. Just get the RDO-194s and don't look back, you'll be happy.

1. Because the mod traces it's origin to a recommendation by Matthew Himself, and
2. I tried it, and I liked it on my 1B, and
3. This forum just went through a very positive experience with swapping Chinese no-name generic voice-coils into SL2000 tweeter bodies, and who said boo about not having any idea of impedance, resonance, dispersion, frequency response or any other factors. Seems kind of hypocritical to accept DIY tweeter repairs using generic voice-coils 'n' domes, but not something that's been introduced by a (perhaps "THE") genuine Polk engineer, and informally (no meters, no instruments) auditioned by several forum members.

Yes, "nothing" tunes the second tweeter in the informal "TL" mod for the 1B/SRS2 blade/blade design. Nothing "tunes" it in the original configuration, either.

I don't think that it's coincidence that most (all?) of the SL2000 speaker designs use a 4.4uF cap in the HF crossover circuitry--or that most (all?) of the SL3000 speaker designs use a 5.8uF cap. Therefore the cap value seems to be the "most important" tuning variable in the crossover to accommodate the upgraded tweeter.

Unfortunately for me, I have neither the mathematics nor the EE background nor the instrumentation to verify any of this in terms of science or measurements. Yes, I'd love to have Matthew post on here that the mod has become "official"; although I think that's unlikely for reasons other than audio quality--I suspect the guy just doesn't have the excess time.

The original SL2000 and the SL3000 were significantly different designs. The '3000 was ferrofluid cooled, and had a vastly different dome material. I'd just love to know what, exactly, is the difference between the RD0-194 and the '198. If I were making a guess, I'd say they're identical except for the voice-coil windings. Same magnet, same housing, same dome material, and no ferrofluid in either one--but I could be wrong.

lbcgav

Sorry to start this thread and leave without checking...I made a move across the country in the meantime. Thanks all for the replies. I decided to go the safest route and just use the RDO194's. I did the upgrade about a month ago and these speakers are really wonderful. I used Sonicaps in the upper section and Audyn Caps in the lows. Mills resistors replaced all the sand resistors.