Should i buy these SDA-2A?

cascius

Hi everyone,

I have the opportunity to get a pair of SDA-2A from a friend for a whooping $100. Of course there's a catch (or rather 2... ): from what he told me it sounds like one driver rattles above a certain level and also he doesn't have the interconnect cable. I haven't listened to those babies yet, but plan to do so next week.

So a few questions:
1. Will my Carver AV 705x be enough to drive those? I can run the other speakers from my Pioneer pre-amp if needed. I've read about the need for an amp with common ground but couldn't find any info on whether the Carver does...
2. From what I've read it should be pretty easy to make my own interconnect. Is that the right assumption?
3. Considering the price, do you think it would be worth it to get these speakers and fix them myself? I'm hopping I'll just have to swap one of the drivers, but who knows...
4. Finally, and I'm pretty sure I already know the answer: would you recommend this upgrade over my Monitor 70s? This would be used for my small home theater room, so 75% movies, 25% music.

Thanks in advance,

- Olivier

PS: If I get positive feedback from fellow polkies, I'll then work on convincing the wife on the huge speakers... lol!

cascius

Thanks xcapri79, that's what I thought as well. $100 isn't much at all. The tricky part is going to be to audition those. From what I know they are currently powered with some not so great pre-amp... So between that and the fact that one driver is probably blown, they might sound like crap...

Now I was just lurking the forums and in another thread people seem to say that going for 2Bs would be much better... Which of course adds another layer of complication... lol

And you're right, the 70's have been pretty good so far. They were definitely a huge upgrade from my Onkyo Home Theater in a box... I bought myself a descent pair of headphones + headphone amp recently and now feel that the 70's aren't quite up to par for music...

Does anyone have any inputs? (including for my other questions?)

Edit: I was just listening to David Bowie - Space Oddity on the 70's with +sub, switched to Pure Direct (ignoring all EQ settings and Sub, and all of a sudden they sound 500% better...)

teekay0007

Those SDA-2As, when brought up to snuff, will blow the Monitor 70s away. Dave (Westmassguy) has a nice pair of 2As that he fully modded and he'd be happy to share more info on them with you - including an informed comparison with the 2Bs. He can also answer any questions you might have about modding/upgrading them since he did his own and many other members' pairs around here.

I think Dan (Endersshadow) used to use a Carver AV 705x amp. I'm not sure if he'd know if it is common ground though, since he used it to power his LSi series speakers.

If those 2As are in good condition, they are a steal at $100, even if one of the drivers is bad.

F1nut

1. I'm not sure about the Carver. You can test it with a meter.
2. Yes.
3. Yes.
4. For 2 channel music they would be an upgrade. The issue with using them as L/R for HT is they will not be a perfect timbre match to your center.

cascius

Cool, hopefully someone else will have some inputs on the carver. By the way I imagine that my pioneer vsx-12th wouldn't be enough to properly power them right?

Other question: what should I be wary about when testing the speakers? Are there any guidelines? Obviously I'll bring some of myouth favorite CDs to test but is there anything to watch out for?

Thanks,

Olivier

Nightfall

Gently push in the passive radiator. If the midwoofer retract to their original position quickly, there is an air leak somewhere. Possibly a tear in one of the rubber surrounds, possibly a bad or poorly seated gasket, and possibly cabinet damage.

Gently push in the midwoofers from the center (outsides of the dust cap). If they "scratch" when moving in, that midwoofer needs to be replaced. Probably magnet shift. $50 per replacement woofer.

Put your ear up to each tweeter, make sure they're all playing. $50 per replacement tweeter.

That's about all I can think of. Unless they're completely trashed, get them. You won't miss your Monitor 70's. Just ask nbrowser, a member here. He had a pair much more expensive RTiA's and just bought a pair of SDA's. The RTiA's have been replaced. Upgrade them such as westmassguy's and there isn't even a contest.

westmassguy

The 2As are a steal at that price, if the cabinets are in decent shape, bad driver or not. MW6510s are easy to find on eBay, or directly from Polk Customer Service. The 2As do have limitations versus the 2Bs. You are limited to common ground amplifiers, and said amplifier must be able to drive <4 ohm loads. The 2As are 4 ohm, and drop to 3.5 at certain frequencies. When fully upgraded, they are 3.5 ohms, and drop well below 3 ohms. The 2Bs are 6 ohm, and are easier to drive. Out of the box, you must use a common ground amp with the 2Bs as well, but with the AI-1 or Dreadnaught interface, any amp can be used, common ground or dual mono. The crossovers on the 3rd generations SDAs will always be more expensive to upgrade vs the 4th or 5th generation when using quality parts. If you plan to upgrade them yourself, the component costs will be about $150.00 more for the 2As vs the 2Bs, due to the large capacitors in the sub-bass drive circuit. Sonically, when given the same upgrades, the 2As and 2Bs are equals. You can jury-rig an interconnect for testing purposes, just make sure the same wire goes from small blade to small blade, large blade to large blade, otherwise the amp will shutdown, or go up in flames. I would not buy or hunt down a blade/blade interconnect. Make a new one with SpeakON connectors, and your favorite flavor speaker cable. As Jesse pointed out, integrating them into a Home Theater can be problematic. The Polk CS350-LS is a good match timbre-wise. I chose to roll my own, using vintage Polk components for a perfect match.
You can read a decent review of your Carver amp here: http://thecarversite.com/yetanotherforum/userfiles/Carver AV-705x review.pdf
In two channel operation, it will handle 4 ohms easily, and 2 ohms as well.
Since it has a single transformer I'm guessing it's most likely common ground, but I would check first with a meter and do as much digging as possible to confirm it.
If you do end up using the Carver for the 2As, use it only with the 2As. They won't like sharing, and they'll eat up everything the Carver puts out.

BDT

Buy'em. Fix 'em. Listen to 'em.

Look. This whole amplification thing...we've done this before but you don't need a billion watts. SDA's aren't particularly difficult to drive. I've only run across ONE speaker that amp juice was an issue....the original Carver Amazing.

If you got 25wpc and a couple of db of headroom....you can drive 95% of the speakers on the planet to more than satisfying levels. Trust me, I've done it.

BDT

BDT

Oh, and if they are ganked up....I'd say 50 bucks.

Never pay asking price for something that isn't 100%.

BDT

boston1450

^^^^^ listen to the NewBee on here he knows his stuff
..
edit:: Good to see you back on here Troy

MrBuhl

For $100 - I would!

westmassguy

BDT wrote: »

Buy'em. Fix 'em. Listen to 'em.

Look. This whole amplification thing...we've done this before but you don't need a billion watts. SDA's aren't particularly difficult to drive. I've only run across ONE speaker that amp juice was an issue....the original Carver Amazing.

If you got 25wpc and a couple of db of headroom....you can drive 95% of the speakers on the planet to more than satisfying levels. Trust me, I've done it.

BDT

I beg to differ. My 2As, which are heavily modified, shut down my Pioneer Elite within seconds, running 2 channel, pure direct.

boston1450

There was a set local here for 150 & i talked with the buyer who bought them 4/5 days later at the store & he said his Onkyo wouldnt push them & went into Protection Mode ?? I dont know the details/cant remember the Onkyo he has using. I told him to get a amp that would dip below 4ohms & he should be fine

BDT

westmassguy wrote: »

BDT wrote: »

Buy'em. Fix 'em. Listen to 'em.

Look. This whole amplification thing...we've done this before but you don't need a billion watts. SDA's aren't particularly difficult to drive. I've only run across ONE speaker that amp juice was an issue....the original Carver Amazing.

If you got 25wpc and a couple of db of headroom....you can drive 95% of the speakers on the planet to more than satisfying levels. Trust me, I've done it.

BDT

I beg to differ. My 2As, which are heavily modified, shut down my Pioneer Elite within seconds, running 2 channel, pure direct.

Then something is wrong with either the speakers or the amp.

SDA's, IIRC were in the order of 89db 1W/M.....the impedance curve wasn't all that severe either.

BDT

westmassguy

BDT wrote: »

westmassguy wrote: »

BDT wrote: »

Buy'em. Fix 'em. Listen to 'em.

Look. This whole amplification thing...we've done this before but you don't need a billion watts. SDA's aren't particularly difficult to drive. I've only run across ONE speaker that amp juice was an issue....the original Carver Amazing.

If you got 25wpc and a couple of db of headroom....you can drive 95% of the speakers on the planet to more than satisfying levels. Trust me, I've done it.

BDT

I beg to differ. My 2As, which are heavily modified, shut down my Pioneer Elite within seconds, running 2 channel, pure direct.

Then something is wrong with either the speakers or the amp.

SDA's, IIRC were in the order of 89db 1W/M.....the impedance curve wasn't all that severe either.

BDT

Nothing wrong with the Receiver or Speakers.

Taken from a Julian Hirsch review of the 2As. Keep in mind with the Sub-Bass Drive Inductor replaced with a low resistance Super Q, the overall Impedance is even lower:

BDT

If you understand what that actually means, it says just about what I said. It's a pretty easy speaker to drive...and, an amp with about 20wpc in good working order with a couple of db and you can just about rupture your ear drums.

All this...you have to have 200wpc blah blah blah is absolute nonsense.

If what you say is true...and there is nothing wrong with the speakers, your amp sucks.

SDA's were designed to be fairly easy to drive....

BDT

westmassguy

We'll have to agree to disagree. Keep in mind the OP is planning to use these for 2 channel, and Home Theater.
I don't know you, or who you are, you may be gods gift to the audio world, you may have forgotten what I know about speakers and amps, I really don't care. I don't appreciate the snarky attitude, and telling another member their equipment sucks. You must be an absolute joy to be around. Not everyone has unlimited discretionary funds, we have what we have.

machone

Your eardrums will rupture from overdriving the amp.

boston1450

To the Opening Poster. Buy them at that outstanding price & play around with them some. Try different amps/receivers & you make the decision. Ive hooked & unhooked 3-4 amp/receivers just to hear the difference. If you dont have resources i would say listen to someone who owns them. They can be valuable information for you. Good luck with your decision

boston1450

Worse case-you can sell them off & be done with them. You shouldnt loose anything with that price

aprazer402

Agreed that the price is sweet. ^^^^ boston1450 has sage advice. Westmassguy knows the 2A's (and all Polk's) very well (it's his business), he's made many comments regarding them in other posts. The 6510MW's as mentioned before are plentiful on auction sites. You can't lose. Best wishes.

cascius

Thanks so much for all the help everyone, this has to be one of the most useful forums i've ever joined!

I'll get those puppies next week and test them. This is going to be fun.

I will also do some research on how to test my amp to see if it's common ground.

Thanks,

Olivier

BDT

westmassguy wrote: »

We'll have to agree to disagree. Keep in mind the OP is planning to use these for 2 channel, and Home Theater.
I don't know you, or who you are, you may be gods gift to the audio world, you may have forgotten what I know about speakers and amps, I really don't care. I don't appreciate the snarky attitude, and telling another member their equipment sucks. You must be an absolute joy to be around. Not everyone has unlimited discretionary funds, we have what we have.

.

You can do what you wish.....It doesn't matter what the application is, math is math. I'm not the brightest guy in the world but, I've owned enough speakers and amps to know that a competently designed and operating 20wpc amp (NAD made millions of them...the 3020) will drive just about any speaker on the planet as hard as your ears can safely take. I know, not only because I can do the math....but for sh*ts and grins, before I bring a pair of speakers in the house, I hook them up to my little Marantz 2215 (15wpc) garage rig receiver just to make sure the speakers operate as they should.

Now, the 2A's.....read what Julian (I never met a speaker I didn't love) Hirsch wrote on the specs. The impedance dips to 3.5ohms between 100-130hz....that's a pretty narrow window. For much of the FR....it's 10ohms. That's pretty amp friendly....if you do some digging, you will find Matt designed these things to be amp friendly for a reason. Now, 88db.....that means that if you sit 1 meter away, it takes 1 watt to get 88 decibels...which, IMO is pretty loud. I forget exactly the math by increasing the distance and so forth...but the point is, the math is that you don't need gobs of power. So, I'm sorry if that offends you but it is what it is....so if you are telling me that at a reasonable level, you've got an amp that's going into protection at normal listening levels....either something is broken or you've got a not-competently designed amp (which I would define as sucks). It doesn't matter if the application is 2channel, Home Theater or just amplifying your farts to scare the neighbors.....an amp is an amp. The application thereof is not the point.

You can argue all you want, not like me....whatever but the facts is the facts is the facts and in your self described scenario either something is broken or your amp is not competently designed (which I would define as sucks). Sorry if that offends your sensibilities....

Oh, and I'm an absolute joy to be around.....ask around, people love me.

BDT (of the not very deep pocketed BDTs)

BDT

To the OP.....I wouldn't worry about common ground. Unless it says dual mono (and even then most of those are common ground)....I wouldn't worry about it.

BDT

westmassguy

So in essence, we should all be using 25 watt amps with our SDAs, because we don't need any more than that. We shouldn't worry about whether an amp is common ground or not. We shouldn't worry about whether that 25 watt amp is even rated for sustained 4 ohm loads.
That goes against everything I've learned from other Senior Members here.
Since I don't know you, I'll take their advice over yours any day.
BTW Julian Hirsch was well respected until the very end of his career.

BDT

Ugh.

Ok, in terms of amps. Quality over quantity. If an amp sounds good and is competently designed....I'd have no problem with using a 25wpc amp driving SDA's. In fact, I drove my 2.3tl's for a long time with a 50wpc CJ tube amp. I'd take a pair of Levinson ML-2's at 25wpc over a YORX a$$wopper 2000 rated at 500wpc. See what I'm getting at here? Quality over quantity.

No, you really don't need to worry if an amp is common ground because 99.9% of them are. Monoblocks aren't by definition. The only time you really have to wonder is if it's a dual mono design and even then....most times they do share the same ground. Again, it's just common sense....there just aren't many non-common ground amps out there.

Julian Hirsch was well respected but he had a serious case of wood over every speaker he reviewed. Does that make him bad? Not at all....I'm just pointing out that he wrote a lot of rave reviews.....but in what you posted, the specs, they confirmed exactly what I said: SDA's are not power hungry speakers. They are a relatively easy load for an amp to drive. You see 3.5ohms and, well, there you are......the impedance curve for all speakers fluctuates. For the SDA's it's well over 8ohms for most of the graph. For a VERY tiny window it dips a little below 4 ohms. It's just not a big deal.

I don't care if you take my advice...and you can believe what you wish, but by telling someone that you NEED gobs of power and by God, you better be sure your amp is common ground....you are passing out bad info.

What do I know? I know I've owned more than a few SDA's. CRS, 2B's, 2A's, 2.3tl's.....I've owned a lot of amps. Some with lots of power...some with not so much power. I drove my 2.3tl's with a pair of Heathkit 25wpc monoblocks for a long time. So, I do have some practical experience. The SDA design? Matt Polk told me and a few others about that in Mark Nestor's kitchen about 10 years ago at Polkfest (which I've hosted a few times)......they were easy to drive because the people that bought SDA's (non audiophiles...SDA's were poo-poo'd by the audiophile community...except for Julian Hirsch) were prone to using lower powered receivers and so forth. They were built for the masses. Hey, what would Matt Polk know though, right?

Look though....you are convinced of what you are convinced of...and that's fine. I believe what I believe. Let's just shake hands and move along.

BDT (of the not knowing much BDT's)

westmassguy

BDT wrote: »

but by telling someone that you NEED gobs of power and by God, you better be sure your amp is common ground....you are passing out bad info.

I never said he needed gobs of power, what I said was his amp needed to handle <4 ohm loads. Telling people that need to verify their amp is common ground is bad info?
There's a label on the back of every SDA, and written in bold in every owners manual about using common ground amplifiers.

BDT

No, but the implication is that, well, my amp goes into protection.....so, therefore, SDA's require lots of power. No, they don't. They require a competently designed amp. End of discussion. Keep tap dancing if you like.

Yes, I know about the frigging warning. I'll stipulate. However, pay attention in case you missed it, there are not many non-common ground designs out there. If you know something that I don't...by all means. The surgeon general probably recommends that you don't conjugate with a prostitute with leprocy without protection.....but, since there aren't many leper prostitutes running around, it's really not that big of a deal either. Capisce?

BDT

westmassguy

This conversation is over, and I'll stick with my original opinion, that you must be an absolute joy to be around. Have a great day!

BDT

If you exercise some common sense and act accordingly...I am a joy to be around. I'm sorry you got your panties in a wad but, fact is, my points are correct and are good, sound advice.

I'm sorry you got your panties in a bunch over it, really, I am but there isn't much I can do for you there. I didn't mean anything personal but the fact is A. you don't need a ton of power to run most speakers, including SDA's and B. Non-Common ground amps are rare enough to be and inconsequential factor. Scaring people off telling them that SDA's are tough speakers to drive and so forth and to be careful about amps for grounding issues is silly and it's not helpful to anyone. I prefer to hand out common sense advice. IE. I'd hate to see someone pass on, say, a NAD 3020 for a X brand receiver with 200wpc (1 channel driven with all windows and doors open and a full tail wind)....because of power ratings or possible ground issues. That would be dumb. The 3020 will run circles around most receivers with 10 times the power ratings. Paul DiComo "Polk" Paul used to (when he worked for NAD) as a demo...wire up 2 pair of AR9's (reducing the load from 4ohm to 2ohms) to a NAD 3020 just to prove how bullet proof they are to dealers.....again, this isn't my knowledge, I'm just passing on what I know...

BDT (of the original Senior Member BDT's)

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BDT

If you have an AVR that can't handle a 4ohm speaker. It sucks. I've had AVR's from Denon and Oinkyo that have handled SDA's no problemo regardless of source material.....

If yours can't, it sucks. If you take that personally, your skin is way too thin. Go join Club Oprah. I'm not talking past anyone. I read exactly what he said my responses and so forth are tailored to that. If westmassdude can't pick up what I'm laying down....eh, what can I tell you. You don't need a Little Orphan Annie secret circle decoder pin, I don't think.

Get educated. Learn about your gear before purchasing.

BDT (of the learned most of this the hard way BDTs)