SDA Owners - How Active Are Your Drivers?

msg

quick report here fellas. I brought out the Monitor 10's for comparison testing.

even with them being poorly positioned a little more than 2ft out from the wall and sitting on carpet, they're still putting out more bass than the 2.3's. something's obviously wrong here.

at first I was thinking it could be something to do with this common ground question with the HCA-3500, considering it's specced as dual mono, but then remembered that the speakers sounded thin on the HCA-2205 as well, which isn't dual mono. could still be that, as well, I suppose, though the negative terminals do show 0.3 ohms resistance with everything disconnected.

I was planning to have the crossovers upgraded, but wanted to try to rule out a few things before I do.

when I was trying to figure out the common ground question, I spoke with Parasound, and Richard checked with the techs and came back and told me that the negative terminals could be strapped. it wasn't actually a solid "yes" to the common ground question. so I just put that in my back pocket, and pressed on with the resistance test and seeing that it came up low resistance, as well.

I don't really know what to make of this at this point.
as a last effort, I'd planned to move them into a smaller space to see how they do in there. just to see. if they suck in there too, then I know for sure something's screwy with the speakers. was also going to try a different amp just to see.

what would happen if the channels weren't sharing a common ground with the SDA cable connected? bigger problems than just weakness in bass and lower mids?

Schurkey

NORMAL STEREO: Do you have a distinct left and right image? Or is everything crammed into the middle of the soundstage almost like goofy, "wide monophonic"?

If I were making a guess...and I am...I'd say you have ONE speaker wired in reverse polarity, either from source to preamp, preamp to amp, amp to speaker cabinet, or inside the cabinet. Since your other speakers have reasonable bass, I'm further guessing that the problem is at or inside the speaker cabinet. Having one speaker in reverse polarity KILLS the bass, and while the midrange and highs are less affected, the left/right soundstage collapses into mush in the middle.

The Stereophile Test CD 1 is superb for disclosing single-channel polarity problems, but any stereo recording with good left/right separation is useful. An SDA speaker should sound like a strong left or right signal is coming from the far left, or the far right, of the actual cabinet.

http://store-badz031c.mybigcommerce.com/stereophile-test-cd-1/?page_context=category&faceted_search=0



If BOTH speakers are getting reversed polarity, there's a different sonic signature. Danged if I can remember what it is. I'm kinda thinking that zero SDA effect is part of that deal.

Your "dual-mono" amp is NOT the problem as you have only 0.3 ohms of resistance, although putting a jumper wire in there won't hurt. I had 20 ohms of resistance between the channels of my amp, and the 1Bs were unlistenable. Another member with the same amp was causing the amp to shut down when powering his...3.1TLs (???). A jumper wire fixed the problem for me.

F1nut

I know you checked the polarity and said all was good, but I can't think of what else it would be. At this point I think you need to check from the binding posts to the crossovers and then to the drivers. It's possible some wires are in the wrong place in the Molex connectors. Check the inductors for a broken wire too.

tonyb

Certainly sounds like a polarity issue. Just for giggles though and maybe I missed it, but isn't the Parasound HCA-3500 a non common ground amp ? SDA cable connected ?

If all the wires are in the right place as Jess suggested, then I'm thinking crossover issue. I know the drivers are 26 years old, but all of them failing at the same time seems unlikely.

westmassguy

I just looked at the manual for the HCA-3500. Dual Toroids, and by all accounts both channels are separate. The rear panel is interesting also, it has inverting and non inverting RCA inputs as well and XLRs. Might want to check exactly how everything is connected.

msg

tonyb wrote: »

Certainly sounds like a polarity issue. Just for giggles though and maybe I missed it, but isn't the Parasound HCA-3500 a non common ground amp ? SDA cable connected ?
If all the wires are in the right place as Jess suggested, then I'm thinking crossover issue. I know the drivers are 26 years old, but all of them failing at the same time seems unlikely.

I do have the SDA cable connected
the 3500 seems to test out as common ground. would I be seeing worse than empty lows if it were not?

westmassguy wrote: »

I just looked at the manual for the HCA-3500. Dual Toroids, and by all accounts both channels are separate. The rear panel is interesting also, it has inverting and non inverting RCA inputs as well and XLRs. Might want to check exactly how everything is connected.

thanks, I have checked the cabling, and will check it again.
each time I swear it's all correct, but I'm sure we've all "seen" things at times.
I should note that these speakers have always sounded like this since I've had them; even when connected to the HCA-2205 amp.

I have considered just flipping one of the inverting switches to see if it fills in. that would be a quick way to check for reversal, wouldn't it? same as swapping pos/neg wires at the speaker? Is there a danger in this, or does it just reverse? obviously, I should do this with the system running, volume up, and wet both ends and tap together to check for spark before inserting, but aside from that?

Schurkey wrote: »

NORMAL STEREO: Do you have a distinct left and right image? Or is everything crammed into the middle of the soundstage almost like goofy, "wide monophonic"?

I'll check for this again. iirc, I was getting a nice center image, but not much else, and certainly not extending past the width of the speakers.

I tested for SDA driver activity.
- BAL R, all R ST, and output on L SDA drivers
- BAL L, all L ST, and output on R SDA drivers

I will check again with the 2.3's for distinct L and R stereo
with the M10's, I get a nice strong center, and can pick out L & R.

If I were making a guess...and I am...I'd say you have ONE speaker wired in reverse polarity, either from source to preamp, preamp to amp, amp to speaker cabinet, or inside the cabinet. Since your other speakers have reasonable bass, I'm further guessing that the problem is at or inside the speaker cabinet. Having one speaker in reverse polarity KILLS the bass, and while the midrange and highs are less affected, the left/right soundstage collapses into mush in the middle.

this is insightful, thank you, and it does seem inline with what I am experiencing

The Stereophile Test CD 1 is superb for disclosing single-channel polarity problems, but any stereo recording with good left/right separation is useful. An SDA speaker should sound like a strong left or right signal is coming from the far left, or the far right, of the actual cabinet.
If BOTH speakers are getting reversed polarity, there's a different sonic signature. Danged if I can remember what it is. I'm kinda thinking that zero SDA effect is part of that deal.

I checked out that Stereophile test cd and ordered one. It arrived the other day, but I haven't had a chance to check it out yet

Now that Radio Shack is no longer around locally, anyone got any recommendations for a decent SPL meter? Saw a bunch on Amazon, even some "RS" ones, but not sure which one people like best.

Your "dual-mono" amp is NOT the problem as you have only 0.3 ohms of resistance, although putting a jumper wire in there won't hurt. I had 20 ohms of resistance between the channels of my amp, and the 1Bs were unlistenable. Another member with the same amp was causing the amp to shut down when powering his...3.1TLs (???). A jumper wire fixed the problem for me.

which amp did you have 20ohms R on?
yeah, I think the amp should be good, but am always open to considering possibilities. given that I had the same experience on a different amp, pretty sure the 3500 is okay here.

had some good recommendations here so far, guys, thanks.
I've been in discussions with WMG regarding the crossover upgrade, so will be proceeding with that regardless, but in the meantime I do plan to explore the wiring a bit. I would like to see if I can determine the problem before we rework the crossovers and possible not solve the problem. Seems like most suspect reversed polarity somewhere, with tired crossovers secondary to that. Everything appears properly cabled and such outside, but I've not yet checked the wiring internally, so it looks like that should be the next logical step. Does seem to make sense that something is wired out of phase, and how that might cause cancellation at the lower frequencies.

I'll test what I can with the recommended Stereophile cd - maybe even just one speaker at a time will reveal the issue. Even if one is wired incorrectly, they should be still make bass individually, shouldn't they? Then I will inspect the interior wiring and crossover against the schematic.

gimpod

westmassguy wrote: »

I just looked at the manual for the HCA-3500. Dual Toroids, and by all accounts both channels are separate. The rear panel is interesting also, it has inverting and non inverting RCA inputs as well and XLRs. Might want to check exactly how everything is connected.

Despite the 0.3 Ohms measured between the L + R neg output post this amp is not a common ground amp. Separate ac inputs and power supply's for the left and right channels makes this a true dual mono block design amp and should not be used with your SDA SRS 2.3TL's unless you have a AI-1interconnet cable, a Dreadnought or can strap the left and right negative speaker terminals together (call Parasound Tech Support @ 1-415-397-7100 7 a.m. - 5 p.m. Pacific Time on this one), To use this amp with the stock interlink cable connected is just asking for trouble you could blow the amp, speakers or both.

I would call Parasound and find out for sure. JMO

msg

gimpod wrote: »

westmassguy wrote: »

I just looked at the manual for the HCA-3500. Dual Toroids, and by all accounts both channels are separate. The rear panel is interesting also, it has inverting and non inverting RCA inputs as well and XLRs. Might want to check exactly how everything is connected.

Despite the 0.3 Ohms measured between the L + R neg output post this amp is not a common ground amp. Separate ac inputs and power supply's for the left and right channels makes this a true dual mono block design amp and should not be used with your SDA SRS 2.3TL's unless you have a AI-1interconnet cable, a Dreadnought or can strap the left and right negative speaker terminals together (call Parasound Tech Support @ 1-415-397-7100 7 a.m. - 5 p.m. Pacific Time on this one), To use this amp with the stock interlink cable connected is just asking for trouble you could blow the amp, speakers or both.

I would call Parasound and find out for sure. JMO

I can give them a call. What should I ask specifically?

When I spoke with Richard last, asking specifically whether the unit was common ground, he checked with the techs and they said the negative terminals could be strapped. I asked twice, but that's really all the info that was conveyed - the negative terminals can be strapped.

Do I need more than that? Or is this enough to say that Dreadnought or strapping is required?

Thanks for the heads up on the potential for damage. I have no understanding of how this would work.

Schurkey

gimpod wrote: »

Despite the 0.3 Ohms measured between the L + R neg output post this amp is not a common ground amp. Separate ac inputs and power supply's for the left and right channels makes this a true dual mono block design amp and should not be used with your SDA SRS 2.3TL's unless you have a AI-1interconnet cable, a Dreadnought or can strap the left and right negative speaker terminals together (call Parasound Tech Support @ 1-415-397-7100 7 a.m. - 5 p.m. Pacific Time on this one), To use this amp with the stock interlink cable connected is just asking for trouble you could blow the amp, speakers or both.

I would call Parasound and find out for sure. JMO

You're WAY smarter about electronics than I am, but I don't understand how you come to this conclusion. I'm puzzled.

Schurkey wrote: »

Your "dual-mono" amp is NOT the problem as you have only 0.3 ohms of resistance, although putting a jumper wire in there won't hurt. I had 20 ohms of resistance between the channels of my amp, and the 1Bs were unlistenable. Another member with the same amp was causing the amp to shut down when powering his...3.1TLs (???). A jumper wire fixed the problem for me.

A jumper wire will cost something like five dollars, perhaps less. At bare minimum, you'll take a piece of 16 gauge wire, cut it to length, and clamp it into the negative terminals between the two channels. Better would be a pair of pin- or banana terminals on 16- or heavier wire to prevent the ends from getting frayed. In short, it takes little or no money to test this, and little more effort and money to do it "nice". I put banana ends on an 8-inch piece of 12-guage automotive primary wire--works perfectly and cost practically nothing.

So, sure, give a jumper wire a try. Can't hurt. I can imagine a scenario where an ohmmeter would show 0.3 ohms, but the conductors through the "guts" of the amp were incapable of carrying the necessary current in actual use with SDA speakers.

Realistically, I'd be VERY surprised if this was the case. I have every expectation that having measured 0.3 ohms, that amp is GOOD TO GO.

My Aragon amp is "Dual Mono", has dual transformers (but not dual power cords), "Dual Mono" almost universally refers to the power supply including the voltage rails. "Dual Mono" doesn't mean squat on the negative side, where the only thing separating the two channels is a pair of 10-ohm resistors, one between each negative post going to chassis ground. 20 ohms across the two resistors makes the amp unsuitable for SDA speakers. A jumper wire easily "cures" this. Many other amplifiers, some of which don't claim "Dual Mono" are also built with resistor pairs in the negative circuit between negative terminals and ground. I think this is to improve channel separation, or perhaps to reduce noise, but I'm not really sure. Re-design the circuitry to remove the two resistors in favor of direct-to-chassis grounding, and that "dual mono" amp would be just fine without the jumper wire. This is the way I suspect your Parasound is built.

PLEASE try a jumper wire between the negative terminals...but be prepared for a big, fat, nothing. I think you're already there.

westmassguy

Scott, I would get the name, first and last, with the guy you spoke with, and even ask for one of the actual techs. Without a schematic, there's no way to know what's going on inside that amp. I'm inclined to go with Tony on this, and err on the side of caution. If it works, fine. I'd be more than happy to furnish a nice jumper for you, along with everything else.

gimpod

msg wrote: »

I can give them a call. What should I ask specifically?

Is this amp a common ground amp and if not can you strap the left & right negative speaker post together.

msg:2144448 wrote:

When I spoke with Richard last, asking specifically whether the unit was common ground, he checked with the techs and they said the negative terminals could be strapped. I asked twice, but that's really all the info that was conveyed - the negative terminals can be strapped.

This statement alone is a red flag as far as this being a common ground amp. To me by the techs saying that you can strap the speaker grounds together are saying in a round about way that this amp is not common ground, otherwise wouldn't you'd think that the tech would say something like "there's no need to strap the grounds as this is a common ground amp"

By the way the only schematic that I could find on this amp only showed one channel and it wasn't very clear on whether it was common ground or not.

If this amp can be strapped then this is a cheap easy way to get you going, A lot of guys around will say unstrap your amp and use a Dreadnought in place of the stock interlink cable it will sound a lot better.

@Schurkey The thing to remember about grounds and resistance is that there are different kinds of each. Grounds can be a star ground, a chassis ground or a signal ground and can be all the same or individual or even a combination of them.

There are two kinds of resistance, D.C. resistance which pretty much stays constant i.e. 20 Ohms is 20 Ohms and A.C. resistance changes with frequency and temperature.

As far as the measured 0.3 Ohms go's I have to ask what range was his meter set for and if this is not a common ground amp then that 0.3 Ohms under load could be anything, remember amps output A.C.

Polkie2009

Schurkey wrote: »

gimpod wrote: »

Despite the 0.3 Ohms measured between the L + R neg output post this amp is not a common ground amp. Separate ac inputs and power supply's for the left and right channels makes this a true dual mono block design amp and should not be used with your SDA SRS 2.3TL's unless you have a AI-1interconnet cable, a Dreadnought or can strap the left and right negative speaker terminals together (call Parasound Tech Support @ 1-415-397-7100 7 a.m. - 5 p.m. Pacific Time on this one), To use this amp with the stock interlink cable connected is just asking for trouble you could blow the amp, speakers or both.

I would call Parasound and find out for sure. JMO

You're WAY smarter about electronics than I am, but I don't understand how you come to this conclusion. I'm puzzled.

Schurkey wrote: »

Your "dual-mono" amp is NOT the problem as you have only 0.3 ohms of resistance, although putting a jumper wire in there won't hurt. I had 20 ohms of resistance between the channels of my amp, and the 1Bs were unlistenable. Another member with the same amp was causing the amp to shut down when powering his...3.1TLs (???). A jumper wire fixed the problem for me.

A jumper wire will cost something like five dollars, perhaps less. At bare minimum, you'll take a piece of 16 gauge wire, cut it to length, and clamp it into the negative terminals between the two channels. Better would be a pair of pin- or banana terminals on 16- or heavier wire to prevent the ends from getting frayed. In short, it takes little or no money to test this, and little more effort and money to do it "nice". I put banana ends on an 8-inch piece of 12-guage automotive primary wire--works perfectly and cost practically nothing.

So, sure, give a jumper wire a try. Can't hurt. I can imagine a scenario where an ohmmeter would show 0.3 ohms, but the conductors through the "guts" of the amp were incapable of carrying the necessary current in actual use with SDA speakers.

Realistically, I'd be VERY surprised if this was the case. I have every expectation that having measured 0.3 ohms, that amp is GOOD TO GO.

My Aragon amp is "Dual Mono", has dual transformers (but not dual power cords), "Dual Mono" almost universally refers to the power supply including the voltage rails. "Dual Mono" doesn't mean squat on the negative side, where the only thing separating the two channels is a pair of 10-ohm resistors, one between each negative post going to chassis ground. 20 ohms across the two resistors makes the amp unsuitable for SDA speakers. A jumper wire easily "cures" this. Many other amplifiers, some of which don't claim "Dual Mono" are also built with resistor pairs in the negative circuit between negative terminals and ground. I think this is to improve channel separation, or perhaps to reduce noise, but I'm not really sure. Re-design the circuitry to remove the two resistors in favor of direct-to-chassis grounding, and that "dual mono" amp would be just fine without the jumper wire. This is the way I suspect your Parasound is built.

PLEASE try a jumper wire between the negative terminals...but be prepared for a big, fat, nothing. I think you're already there.

When I was researching the Aragon 8008BB amp for my SDA/SRS2's , I got ahold of Indy Audio Labs asking if the amp was common ground. They informed me about the 20 ohm resistance across the negative terminals and didn't want to recommend using it with the Polks. They didn't mention strapping the neg. posts either, I got the impression they were trying to avoid handing out bad advice and CTA. Can't blame them for that, I suppose. Over time found more and more Polk members using their Aragon amps, negs. strapped running their SDA's with no problems.Concerning the Parasound HCA-3500, I saw a few I was interested in over the past few years in our for sale section but figured they were not common ground amps due to the dual power cords. I should have called Parasound and directed the question to the design or tech staff, but never did.

msg

even so, don't let that scare you off, man - build/buy a Dreadnought.
@westmassguy can build one for you with associated cables, very reasonably priced. my understanding is that it can make an improvement with CG or NCG amps.

VSAT88

I know this post is really old but I really hate it when a solution is not posted. A good bit or reading not to find out what happened in the end..A great read though with lot of wisdom shared..What was it anyways, left and right SDA speaker inadvertently placed in reverse ?

msg

Still unresolved/in storage.
I'm planning to check the end caps as well to see that they're tight, but am resigned to a crossover rebuild at some point.

K_M

To the O.P. I know this is an older thread, and you commented about the Lsi7 and sub having better deep bass, and pondered if that was possible.

It depends on if you have a sub that has fairly decent deep bass capability, combined with it maybe being turned up a few to several decibels higher than normal, it is quite possible to sound louder or deep then the SDA.

Although in your case, something else may also be wrong at the same time.

We own a pair of SDA, not same model, but the bigger ones, and while they have decent deep bass, it never sounds overly loud or strong, but maybe just right or a tad on the lean side. It never really calls attention to it, but it is there, if that makes sense.

Compared with many decent subs, I would say you will not get the same level of deep bass from these, but it should still be quite good, albeit maybe not as spectacular.

Good luck, when you pull them out of storage!!

lightman1

$16!! Final offer!

Viking64

In at $16.37!!!

civilian

Smallies wrote: »

old caps it is. ta-da!

Nice! Resolution, now I can sleep tonight.

Tony M

MSG,

Polarity will KILL a speakers bass in a room. Just like the original members wanted you to check. The sound from a NICE set of speakers will sound like crap if the speaker is red+ and black - and other is reversed.

I've experienced it right here.

Are the plastic wire nuts positioned correctly?

I had a set of CRS's that somebody had switched the nuts on one speaker. Thank GOD for this forum! They helped me figure my dilemma out. And when the signals were going correctly, MAGIC!