The Tale Of 5 Tweeters - SDA Tweeter Replacement Guide
DarqueKnight
Posts: 6,765
Introduction
This article is aimed at those who want to be sure that they are choosing replacement and upgrade tweeters according to Polk's specifications and recommendations. Of course, owners are free to make whatever tweeter and driver replacements/substitutions they wish with their speakers. Some owners my subjectively believe that a non-standard tweeter replacement sounds better.
The five tweeters used in the SDA series are: the SL1000, the SL2000, the SL3000, the RD0194, and the RD0198.
The RD0194 silk dome tweeter is the appropriate replacement for the SL1000 and SL2000. The RD0194 is a drop in replacement for the SL2000, but not for the SL1000 since they are different sizes and have different footprints. Fitting an RD0194 into a cabinet made for the SL1000 will require some cabinet modification.
The RD0198 silk dome tweeter is the appropriate drop in replacement for the SL3000 tweeter used in the fifth generation SDA SRS series and in the RTA 15TL and RTA 11TL. The SL2500 is a cost reduced derivative of the SL3000 design. It was used in the Monitor 2 series speakers and in the RTA 8TL of the RTA series.
An alternative to the newer RD0 silk dome tweeter models is to track down the actual SL series tweeter, but those are not always available. Whatever replacement tweeter is chosen, it is highly recommend to invest in a Dayton Audio DATS V2 Audio Test System ($100) (or a similar speaker tester) in order to make sure that the tweeter is in proper working order.
Table 1 gives the typical electrical performance parameters of four of the five standard SDA tweeters. The nominal impedance of the SL2000 and RD0194 tweeters is 7.5 ohms. The nominal impedance of the SL2500, SL3000, and RD0198 tweeters is 5.6 ohms. The measurements in table 1 were made using the Dayton Audio DATS V2 Audio Test System.
Glossary of terms for table 1:
Qts - A measurement of the total electrical and mechanical control of a driver. (no units)
Qms - A measurement of the control coming from the speaker's mechanical suspension system (the surround and spider). (no units)
Qes - A measurement of the the control coming from the speaker's electrical suspension system (the voice coil and magnet). (no units)
fs - A measurement of the free air resonance of a driver. This is the point at which driver impedance is maximum. It is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion. (measured in Hertz)
Re - The DC resistance (DCR) of the driver. This measurement will almost always be less than the driver's nominal impedance. (measured in ohms)
Zmax - The driver's impedance at resonance. (measured in ohms)
Le - A measurement of the voice coil inductance. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes. Maximum impedance (Zmax) occurs at fs. (measured in millihenries)
The measured values in table 1 provide some quantitative insight into why the RD0 series tweeters are upgrades to the SL series tweeters and why they are subjectively preferred by many SDA enthusiasts.
Test Tweeters
I had SL2000, SL3000, RD0194, and RD0198 tweeters on hand. I found a used SL2500 tweeter and two new old stock SL2500 tweeters on eBay. As of this writing, I have not located SL1000 tweeters that I felt comfortable with purchasing.
Figure 1. SL2500 tweeters.
Figure 2. Column 1-SL2500 tweeters, Column 2-SL3000 tweeters, Column 3-RD0198 tweeters.
Figure 3. SL2500 left, SL3000 right.
The SL2500 is similar in construction to the SL3000, and could be used as a replacement for the SL3000. However, as its overall lower Q measurements show, the SL2500 has lower performance with regard to driver control. This translates to lower performance in reproducing high frequency speed and detail.
Conversely, the RD0 series replacement tweeters have overall better driver control performance than their respective SL series counterparts.
The dome of the SL3000 has a shiny metallic appearance due to its vapor deposited metal layers. The SL3000 dome is composed of a triple layered (Tri-laminate, or "TL") construction with a top layer of stainless steel, second layer of aluminum, and third layer of clear polyamide. The SL2500 has a dull appearance and has a black polymer coating on the front and rear sides. It is not clear to me at this time if the SL2500's dome has a triple layer (Tri-laminate) structure similar to the SL3000's.
Figure 4. Rear side of SL2500 dome, left. Rear side of SL3000 dome, right.
Figure 5. SL2000 left, RD0194 right.
The 1989 versions of the SDA CRS+ and SDA 2B can be modified to support replacement of the SL2000 tweeter with either the SL3000 or RD0198 tweeters. The modification consists of the addition of a 5.8 uF capacitor in parallel with the 2.7 ohm resistor. This modification creates a contour network that corrects the rising high frequency response that would result from installing the SL3000 or RD0198 in these speakers. The SDA CRS+ and SDA 2B use the same crossover circuit.
Phase And Impedance Curves
The following phase and impedance curves for the SL2000, SL2500, SL3000, RD0194, and RD0198 tweeters are given in figures 6-10. In addition to the difference in DC resistance between the SL1000/SL2000/RD0194 and SL2500/SL3000/RD0198 tweeters, the differences in phase and impedance response highlight another reason why tweeter replacements must be chosen with care.
Figure 6. Phase and impedance curves for SL2000 tweeter.
Figure 7. Phase and impedance curves for RD0194 tweeter.
Figure 8. Phase and impedance curves for SL2500 tweeter.
Figure 9. Phase and impedance curves for SL3000 tweeter.
Figure 10. Phase and impedance curves for RD0198 tweeter.
PDF versions of these curves are attached below.
This article is aimed at those who want to be sure that they are choosing replacement and upgrade tweeters according to Polk's specifications and recommendations. Of course, owners are free to make whatever tweeter and driver replacements/substitutions they wish with their speakers. Some owners my subjectively believe that a non-standard tweeter replacement sounds better.
The five tweeters used in the SDA series are: the SL1000, the SL2000, the SL3000, the RD0194, and the RD0198.
The RD0194 silk dome tweeter is the appropriate replacement for the SL1000 and SL2000. The RD0194 is a drop in replacement for the SL2000, but not for the SL1000 since they are different sizes and have different footprints. Fitting an RD0194 into a cabinet made for the SL1000 will require some cabinet modification.
The RD0198 silk dome tweeter is the appropriate drop in replacement for the SL3000 tweeter used in the fifth generation SDA SRS series and in the RTA 15TL and RTA 11TL. The SL2500 is a cost reduced derivative of the SL3000 design. It was used in the Monitor 2 series speakers and in the RTA 8TL of the RTA series.
An alternative to the newer RD0 silk dome tweeter models is to track down the actual SL series tweeter, but those are not always available. Whatever replacement tweeter is chosen, it is highly recommend to invest in a Dayton Audio DATS V2 Audio Test System ($100) (or a similar speaker tester) in order to make sure that the tweeter is in proper working order.
Table 1 gives the typical electrical performance parameters of four of the five standard SDA tweeters. The nominal impedance of the SL2000 and RD0194 tweeters is 7.5 ohms. The nominal impedance of the SL2500, SL3000, and RD0198 tweeters is 5.6 ohms. The measurements in table 1 were made using the Dayton Audio DATS V2 Audio Test System.
Table 1. Measured Electrical Parameters Of SDA Tweeters
Glossary of terms for table 1:
Qts - A measurement of the total electrical and mechanical control of a driver. (no units)
Qms - A measurement of the control coming from the speaker's mechanical suspension system (the surround and spider). (no units)
Qes - A measurement of the the control coming from the speaker's electrical suspension system (the voice coil and magnet). (no units)
fs - A measurement of the free air resonance of a driver. This is the point at which driver impedance is maximum. It is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion. (measured in Hertz)
Re - The DC resistance (DCR) of the driver. This measurement will almost always be less than the driver's nominal impedance. (measured in ohms)
Zmax - The driver's impedance at resonance. (measured in ohms)
Le - A measurement of the voice coil inductance. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes. Maximum impedance (Zmax) occurs at fs. (measured in millihenries)
The measured values in table 1 provide some quantitative insight into why the RD0 series tweeters are upgrades to the SL series tweeters and why they are subjectively preferred by many SDA enthusiasts.
Test Tweeters
I had SL2000, SL3000, RD0194, and RD0198 tweeters on hand. I found a used SL2500 tweeter and two new old stock SL2500 tweeters on eBay. As of this writing, I have not located SL1000 tweeters that I felt comfortable with purchasing.
Figure 1. SL2500 tweeters.
Figure 2. Column 1-SL2500 tweeters, Column 2-SL3000 tweeters, Column 3-RD0198 tweeters.
Figure 3. SL2500 left, SL3000 right.
The SL2500 is similar in construction to the SL3000, and could be used as a replacement for the SL3000. However, as its overall lower Q measurements show, the SL2500 has lower performance with regard to driver control. This translates to lower performance in reproducing high frequency speed and detail.
Conversely, the RD0 series replacement tweeters have overall better driver control performance than their respective SL series counterparts.
The dome of the SL3000 has a shiny metallic appearance due to its vapor deposited metal layers. The SL3000 dome is composed of a triple layered (Tri-laminate, or "TL") construction with a top layer of stainless steel, second layer of aluminum, and third layer of clear polyamide. The SL2500 has a dull appearance and has a black polymer coating on the front and rear sides. It is not clear to me at this time if the SL2500's dome has a triple layer (Tri-laminate) structure similar to the SL3000's.
Figure 4. Rear side of SL2500 dome, left. Rear side of SL3000 dome, right.
Figure 5. SL2000 left, RD0194 right.
The 1989 versions of the SDA CRS+ and SDA 2B can be modified to support replacement of the SL2000 tweeter with either the SL3000 or RD0198 tweeters. The modification consists of the addition of a 5.8 uF capacitor in parallel with the 2.7 ohm resistor. This modification creates a contour network that corrects the rising high frequency response that would result from installing the SL3000 or RD0198 in these speakers. The SDA CRS+ and SDA 2B use the same crossover circuit.
Phase And Impedance Curves
The following phase and impedance curves for the SL2000, SL2500, SL3000, RD0194, and RD0198 tweeters are given in figures 6-10. In addition to the difference in DC resistance between the SL1000/SL2000/RD0194 and SL2500/SL3000/RD0198 tweeters, the differences in phase and impedance response highlight another reason why tweeter replacements must be chosen with care.
Figure 6. Phase and impedance curves for SL2000 tweeter.
Figure 7. Phase and impedance curves for RD0194 tweeter.
Figure 8. Phase and impedance curves for SL2500 tweeter.
Figure 9. Phase and impedance curves for SL3000 tweeter.
Figure 10. Phase and impedance curves for RD0198 tweeter.
PDF versions of these curves are attached below.
Proud and loyal citizen of the Digital Domain and Solid State Country!
Comments
-
Ray, nice work and I'm sure many will benefit from it.
Post edited by [Deleted User] onPolitical Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Outstanding. I have a spare SL1000 I'd be happy to send you Ray.Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
dhsspeakerservice.com/ -
Jesse, I don't do lost causes.
I wish everyone happiness with the tweeters of their choice.
Proud and loyal citizen of the Digital Domain and Solid State Country! -
Outstanding Ray.
-
Proud and loyal citizen of the Digital Domain and Solid State Country!
-
Splendid, thank you. This needs to be preserved for the ages (and I am not being facetious).
-
Very concise write-up. Can you tell if the 194's plastic frame is thinner or cast differently than the 2500/3000 frames?Don't take experimental gene therapies from known eugenicists.
-
I don't think the plastic is thinner, but the casting is very different.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Excellent write up Ray. Thank you for taking the time.
Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:
"I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion."![:\](https://forum.polkaudio.com/resources/emoji/confused.png ":\")
My response is: If you need 60 seconds to respond in one sentence, you probably should't be evaluating Polk speakers.....
"Green leaves reveal the heart spoken Khatru"- Jon Anderson
"Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee -
Can you tell if the 194's plastic frame is thinner or cast differently than the 2500/3000 frames?
Thank you for your question. It allowed me to clear up a long-standing misconception I held about the RD0 tweeters' frame construction.
With all the 2500/3000 frames' extensive cross bracing and deeper curvature, I expected them to be thicker, heavier, and more rigid than the RD0194 frames. The opposite was true.
The RD0194 frame is actually 5.7 grams heavier than the SL3000 frame and 1.29 millimeters thicker at the center cutout. In fact, after taking thickness measurements, I placed the empty frames side by side and could easily see that the frame thickness at the RD0194's center cutout was substantially greater than that of the SL3000. Similarly, the RD0198 frame weighed 30.1 grams and was 3.36 mm thick at the center hole.
The RD0 frames are also more rigid when trying to bend them using two hands.
Upon receipt of my first RD0 tweeters, I vividly recall thinking that Polk had "cheaped out" on the frame construction. In this case my eyes deceived me, so my apologies to Polk for condemnation before investigation.
This measurement exercise provided more insight into the RD0 tweeter's superior electrical and mechanical construction. I wish Polk had done a white paper on these tweeters similar to the one done for the SL3000.
RD0194 frame on left, SL2500 center, SL3000 right. The SL2500/SL3000 frames are identical.
RD0194 frame on left, SL3000 frame on right.
The SL3000 frame weighed 23.8 grams.
The RD0194 frame weighed 29.5 grams.
SL3000 frame thickness around center hole was 2.07 mm.
RD0194 frame thickness around center hole was 3.36 mm.
The RD0198 frame weighed 30.1 grams.
Due to the integrated structure of the frame and voice coil/dome assembly, I could not do a stand alone weighing of the SL2000's frame
Post edited by DarqueKnight onProud and loyal citizen of the Digital Domain and Solid State Country! -
Again, thorough inspection.Thank you. I had a couple 194's that had severe plane run-out (flatness) where they bolted to the baffle. They contorted then resonated in certain frequencies when bolted down.
Don't take experimental gene therapies from known eugenicists. -
Again, thorough inspection.Thank you. I had a couple 194's that had severe plane run-out (flatness) where they bolted to the baffle. They contorted then resonated in certain frequencies when bolted down.
Did you return them for replacement?Proud and loyal citizen of the Digital Domain and Solid State Country! -
Clearly music is subjective because it's an art form and all are entitled to their opinions. When it comes to proven science there should be no wiggle room w the exception of stubbornness. No golden ear here but when I changed out my old scratchy SL1000s to the drop in RDO -194 there was a better and extended listening time w/ the newer replacement tweeters. i can't be any more clear and direct than that......Lew
I did notice that if tightened w/ the machine screws Toolfan provided it could warp the frame so I backed off and w/ the gasket made for an air tight seal...No TL mod here....2chl- Adcom GFA- 555-Onkyo P-3150v pre/amp- JVC-QL-A200 tt- Denon 1940 ci cdp- Adcom GFS-6 -Modded '87 SDA 2Bs - Dynamat Ext.- BH-5- X-Overs VR-3, RDO-194 tweeters, Larry's Rings, Speakon/Neutrik I/C- Cherry stain tops Advent Maestros,Ohm model E
H/T- Toshiba au40" flat- Yamaha RX- V665 avr- YSD-11 Dock- I-Pod- Klipsch #400HD Speaker set-
Bdrm- Nikko 6065 receiver- JBL -G-200s--Pioneer 305 headphones--Sony CE375-5 disc -
To Toolfan, the first set were donated and I kept for another rainy day project. The other set was new and sent back by person I helped with 10b's.
Were going to try the Dayton DC28F when I get some more adapter plates done.
To Dark knight, can you lift the SL2500 vs the SL3000 domes with a strong magnet? Depending on the amalgam of stainless, it may determine whether the 2500 has a metallic layer or not. JATDon't take experimental gene therapies from known eugenicists. -
To Dark knight, can you lift the SL2500 vs the SL3000 domes with a strong magnet? Depending on the amalgam of stainless, it may determine whether the 2500 has a metallic layer or not. JAT
I wouldn't have expected either of the domes to have a magnetic metallic layer due to the tweeter magnet's strong magnetic field. I tried it anyway with the magnet of one of the tweeters and with another strong magnet that I use to clip notes to the side of my refrigerator. There was no magnetic attraction with either the 2500 or the 3000 dome.
The SL3000's dome is translucent and allows points of light through. All of the three SL2500 domes totally block light. I used the "light test" to see if I could see any indication of a metallic layer behind the black polymer coating. One of my SL2500s was manufactured in 1991. The other two were manufactured in 1994.
Light test: SL3000 dome on top of a flashlight.
The SL3000 dome is translucent and allows points of light through.
The layer structure of the SL3000's Tri-laminate dome structure is as follows:
Top-Stainless steel, 0.00000394" thick.
Middle-Aluminum, 0.00000394" thick.
Bottom-Polyamide, 0.004".
Source: SL3000 Dome Tweeter white paper, September 1989.
Light test: SL2500 dome on top of a flashlight.
The SL2500 dome is opaque and blocks all light.Proud and loyal citizen of the Digital Domain and Solid State Country! -
At this point, the only way someone could definitively conclude the sl2500 having metallic layer is via GC/MS. Doubtful anyone here has one in the garage hehe.Don't take experimental gene therapies from known eugenicists.
-
Great write-up, thanks! This will come in handy for many people (including myself).
-
Yes, please pardon my scientific methodology interjection.Don't take experimental gene therapies from known eugenicists.
-
Great scientific analysis from an engineer.
H9.
P.s. I have RD0194's in my 5B's and (2) pairs in my1C's. I have not noticed any sort of vibration, ringing or resonation in the 8 years I've owned them. Not very scientific, but it's my experience so that's really all that matters.
P.s.s Thank you DK for yet another thorough write up and analysis. Definitely very informative.
Post edited by [Deleted User] on"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
As an engineer, I tend to like to see data to support a conclusion. There are times that gathering data is difficult due to lack of knowledge of scientific methods of collecting or lack of proper equipment to do so. Sometimes an observation or opinion is just that without real supporting methods. I think there are 2 completely different things going on here. DK has posted factual data on all the tweeters listed and I have a better understanding of the differences because of it. My interpretation of the way the different sounds produced is my opinion and not a fact. In the end, I use the data to form a better opinion of the real world. I usually don't put out something with out either some data or a theory to support my opinions.Main System
Marantz AV8802A PrePro
Marantz MM7025 Amp rear surrounds
McIntosh MC7205 Amp center, ceiling and mid surrounds
McIntosh MC300 Amp front mains
Oppo 203 Bluray
Polk SDA-SRS with VR3 monastery crossovers
Polk FX1000 Mid surrounds
Klipsch RP-440C Center channel
Klipsch RP-15M Rear surrounds
SVS prime elevation ceiling surrounds
Rythmik F15HP sub
Samsung 8500 curved screen 65" LED 4K
Mac Mini Server
Office System
Musical Fidelity M6s dac/preamp
Oppo 103D Bluray
Polk SDA-SRS 2
Parasound HCA-1500A
Polk PSW 650 sub
Microrendu
Roku Ultra
Mac Mini Server -
GREAT information. TY
Just throwing this out there. Any chance of a similar thread with data for the peerless, Denmark and USA, and maybe even the MT replacement. Non destructive of course. I am mainly curious about the specs.
I'd be curious about the frequency response curves for all of the above, although I think some may be already out there. I know there is one for the SL2000, and I think one was provided for the RD0-198 that showed the attenuation as the frequency increased. -
GREAT information. TY
Just throwing this out there. Any chance of a similar thread with data for the peerless, Denmark and USA, and maybe even the MT replacement.
I wouldn't hold out a lot of hope for that.
Proud and loyal citizen of the Digital Domain and Solid State Country! -
GREAT information. TY
Just throwing this out there. Any chance of a similar thread with data for the peerless, Denmark and USA, and maybe even the MT replacement. Non destructive of course. I am mainly curious about the specs.
I'd be curious about the frequency response curves for all of the above, although I think some may be already out there. I know there is one for the SL2000, and I think one was provided for the RD0-198 that showed the attenuation as the frequency increased.
Do a search Keith (Geppy1) had a thread on those back before the Vanilla switch. -
Great job DK I've bookmarked it, lots of good info here should be a sticky.“The two most important days in your life are the day you are born and the day you find out why.” ~ Mark Twain
-
Great job DK I've bookmarked it, lots of good info here should be a sticky.
Hey, howdy! How are you doing, sir?
-
A little hope it is thenDarqueKnight wrote: »
How many agree's are needed to make this happen.Great job DK I've bookmarked it, lots of good info here should be a sticky.
I found this one, which I knew about. Do your remember one with specs?Do a search Keith (Geppy1) had a thread on those back before the Vanilla switch.
-
No Keith is not like Raife, he does not have the equipment for that.
-
I'm for a sticky for sure!
It's nice to know the replacement tweeters are BETTER than the originals in substance and performance.
They sound softer at first but then they sound right after a couple of weeks. That's my experience with the RD-0194 replacements anyway. Sibilance is greatly reduced too.
Thank you Raife for doing that study! Most people just listen to music and watch movies. I EXPERIENCE them. -
SDA Tweeter Measurements Table Revised To Include SL1000 Tweeter
Thanks to David (@westmassguy) for the loan of the SL1000 Tweeter.
I like the SL1000's elegant brushed aluminum frame.
Table 2. Measured Electrical Parameters Of SDA Tweeters (Revised)
Phase and impedance curves for the SL1000 tweeter.
A PDF copy of the phase and impedance plot is attached below.Proud and loyal citizen of the Digital Domain and Solid State Country! -
Fantastic thread! There's a lot of good information here. Thanks DK.2ch rig: Speakers: Magnepan LRS w/Magna Riser stands Preamplifier: Parasound P5 Amplifier: Parasound A23 CDP: Pioneer DV-563A Cables: Wireworld Equinox 7 XLR ICs, Wireworld Ultraviolet 7 USB, AudioQuest Q2s, AudioQuest NRG X(preamp)
Standby: LSi9s with VR3's Fortress mods
