First post, long time fan, sda2a
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Optemo
Posts: 5
I gave my second pair of M10's to my bro. He didn't use them and asked if I wanted them back. I said yes and then he gave them away to someone. We don't talk much anymore. It's deeper than just the M10's
I got my first M10 set in 1994. I made $16 an hour, so they were a luxury expense. I drove them with a Proton d540. I was so happy hearing them for the first time. Almost 30 years later I have cycled through a few sets of good speakers but I missed the Polk's. My future mother in-law overflowed the tub and flooded the lower room they were stored in. Not a good start to a relationship. The bottoms blew up like those sponge toys you could get for a nickle in a plastic egg near the grocery store entrance. I had some ESS amt1b's that I got for $100 and rebuilt. They sounded great but the look and size got them evicted. Only to have a bigger and just as strange looking lodger move in after them, Infinity rs2's. I got tired of my wife moving them around and complaining about them. "They are huge! They are ugly!" I feared for their safety, so after a last straw nag, I removed them from the house gingerly with a hand truck. She replaced them with garbage and regretted her position immediately. She tried to negotiate bring them back in. I let the lack of bass and tinny distortion set in for a couple weeks.
This week she texts me a picture from the thrift shop of these SDA2a's with the cable. Asking, "are these any good?" I did some web searches and reading, $200 later, they are playing Dark side of the moon in my house. Yup, they are. Now I'm on the CO+TL upgrade path. I though I'd sign up and confirm the return of my Polk speaker head status.
My question Is about those 130uf caps. If they test in spec. Is there a return on the $320+ Solen investment besides reliability? Thanks to all here who have shared and documented. It been a fun dive and I look forward to the mod results.
I got my first M10 set in 1994. I made $16 an hour, so they were a luxury expense. I drove them with a Proton d540. I was so happy hearing them for the first time. Almost 30 years later I have cycled through a few sets of good speakers but I missed the Polk's. My future mother in-law overflowed the tub and flooded the lower room they were stored in. Not a good start to a relationship. The bottoms blew up like those sponge toys you could get for a nickle in a plastic egg near the grocery store entrance. I had some ESS amt1b's that I got for $100 and rebuilt. They sounded great but the look and size got them evicted. Only to have a bigger and just as strange looking lodger move in after them, Infinity rs2's. I got tired of my wife moving them around and complaining about them. "They are huge! They are ugly!" I feared for their safety, so after a last straw nag, I removed them from the house gingerly with a hand truck. She replaced them with garbage and regretted her position immediately. She tried to negotiate bring them back in. I let the lack of bass and tinny distortion set in for a couple weeks.
This week she texts me a picture from the thrift shop of these SDA2a's with the cable. Asking, "are these any good?" I did some web searches and reading, $200 later, they are playing Dark side of the moon in my house. Yup, they are. Now I'm on the CO+TL upgrade path. I though I'd sign up and confirm the return of my Polk speaker head status.
My question Is about those 130uf caps. If they test in spec. Is there a return on the $320+ Solen investment besides reliability? Thanks to all here who have shared and documented. It been a fun dive and I look forward to the mod results.
Comments
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Are you using Solen caps or are you asking about getting the 130uf as a Solen cap?
Yes the big caps in those are a downside. I would use Clarity or Sonicap for everything but the big one, that one you do not have many choices. -
My question is, if the existing 130uf caps are in spec is there anything to be gained with new ones. Are there other factors beyond its uf rating that degrade over time or effect sound. Would replacement justify the expense if they are still in spec? I know new ones will be more reliable long term.
If they are out of spec, this is my conjecture: I think these caps are a high pass filter for the dimensional MW6510 driver. When the caps degrade the uf value shrinks and the result is a filter that lets more bass through than is wanted in the dimensional driver? This would reduce the bass experienced as it is a canceling wave. So "IF" they are out of spec, definitely spend the money to hear more bass? How's that for talking over my head?
I know a $9 130uf start cap is not the same quality as an audio cap. Can anyone tell me why? I know tolerances are an issue. Resistance? Don't last? Maybe interference? What else? -
You can do searches on the rationale and theories behind audiophile capacitors and why capacitors sound different, but it all comes down to the fact that they do sound different. There's more than capacitance. There's Dissipation Factor, Microphonics, Effective Series Resistance, etc..
The tweeter circuit in a XO is the high pass and the low pass feeds the Midwoofers.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Those 130uf caps are Non-Polarized Electrolytics. Do not use a start cap. If you want to save a few dollars on your recap, put some new Audio Grade NP Electrolytics in their place, with some quality MP caps everywhere else. You can always revisit the recap, and use some Dayton 5% MP caps.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/ -
In addition, there's no way 40 year old electrolytic caps are in spec.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 -
Ok, thanks for the good advice. No way they are in spec seem obvious. I haven't had a look at them yet, didn't know they were electrolytic originally. In my reading I found they are referred to as films but they must be talking about the ideal upgrade. That's exciting, more room for improvement in my budget. I get that the XO sends the low signal to the MW's but I think the twin 130uf caps cut the lowest frequencies from just the dimensional driver so that bass is NOT canceled like the higher stereo frequencies are. Maybe I've got that wrong. Going to order the rdo-198's, caps and resistors. Is a group of 4 parallel 65mfd NP electrolytic Ok? I'll go better quality on the small ones.
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The stock high frequency cap is mylar, the rest are electrolytic. Replace all of them with audio grade poly caps. Do not use Solen, Dayton or Bennic in anything but low circuit. Replace the resistors with Vishay Mills. Do away with the polyswitch and replace with 0.5 ohm resistor. Remove and do not replace the bypass cap.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 -
I'm pretty sure that very large inductor is so that the only stereo signal that the dimensional driver can play is the sub bass (low pass) but I forget what the frequency cutoff is. I think you are correct in that the 260uf of capacitance probably has the effect of ensuring that that the only dimensional signal played is above a certain frequency (high pass). I also don't know what that frequency is. I think this speaker was reviewed and I've seen the manual also. The frequencies are in the specs I think.
Edit - Sub bass frequency low pass filter is 150 Hz. Maybe the 260uf high pass filter is 150 Hz??
SDA2A manual: https://www.hifiengine.com/hfe_downloads/index.php?polk_audio/polk_audio_sda-2a_en.pdf
Polk SDA-2A, Stereo Review, Dec. 1986, p. 52:
https://www.americanradiohistory.com/Archive-All-Audio/Archive-HiFI-Stereo/80s/HiFi-Stereo-Review-1986-12.pdfGeorge / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
No comment on my proposed quad 65uf group to make the 260uf? Can I be off by 10uf without ill effect? Thanks for the tips and confirmations of mods. I will report.
More thought: It looks like raising the 260uf cap value would lower the high pass cut off point, putting more bass into the canceling dimensional MW, causing it to cancel out more low end frequencies, less experienced bass. So as the 260uf cap degrades, the capacitance drops, the high pass filter cut point raises, it plays less low end canceling signal, leaving more low frequencies to be heard. That's a fun brain teaser. So a single new 250uf cap would leave a bit more bass. Maybe not a bad thing. I'm guessing I wouldn't be able to hear the difference between 260uf and 250uf. -
I commented, I said replace everything with poly caps.No comment on my proposed quad 65uf group to make the 260uf?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 -
Well the electrolytics were +/- 5 or 10% IIRC
Many paralleled several caps to get the value. On my SDA 2a i did the same for the 130uf and attached them to a board below on the floor of the cabinet then ran wires to the XO board. Can't have that much weight hanging on the board stand off and expect it to hold for long
I used Axon caps for those. -
No comment on my proposed quad 65uf group to make the 260uf? Can I be off by 10uf without ill effect? Thanks for the tips and confirmations of mods. I will report.
More thought: It looks like raising the 260uf cap value would lower the high pass cut off point, putting more bass into the canceling dimensional MW, causing it to cancel out more low end frequencies, less experienced bass. So as the 260uf cap degrades, the capacitance drops, the high pass filter cut point raises, it plays less low end canceling signal, leaving more low frequencies to be heard. That's a fun brain teaser. So a single new 250uf cap would leave a bit more bass. Maybe not a bad thing. I'm guessing I wouldn't be able to hear the difference between 260uf and 250uf.
Don't overthink this. Here's a photo of my 2Atls with 3 X 90uf Daytons totaling 270uf. You can also go 2X 90uf + 75uf for 255uf total. You'll never hear the difference
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/ -
No comment on my proposed quad 65uf group to make the 260uf? Can I be off by 10uf without ill effect? Thanks for the tips and confirmations of mods. I will report.
More thought: It looks like raising the 260uf cap value would lower the high pass cut off point, putting more bass into the canceling dimensional MW, causing it to cancel out more low end frequencies, less experienced bass. So as the 260uf cap degrades, the capacitance drops, the high pass filter cut point raises, it plays less low end canceling signal, leaving more low frequencies to be heard. That's a fun brain teaser. So a single new 250uf cap would leave a bit more bass. Maybe not a bad thing. I'm guessing I wouldn't be able to hear the difference between 260uf and 250uf.
I think the only thing that could be cancelled is the interaural crosstalk. That isn't needed with the very low frequencies probably because of their relative non directionality and the longer wavelength. They decided to draw the line at 150 Hz but I don't think it is super critical.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I used the solen 130uf capacitors in my 2a's, I also changed the inductors and it made a nice change for the better.
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Thanks all for the good info. I just got swamped with work right when I thought I'd have the time to do this. Looks like $450 to do this with out going hi end cap crazy. I'll report back when I've made progress.
