Buying Polks on EBAY

candyliquor35m

Hi folks, newbie here. Is ebay the best place to buy a pair of the SDA-SRS's other than sheer luck such as finding one in the local paper or pawn shop?

madmax

Ebay, audiogon or here. What are you looking for and where do you live?
madmax

candyliquor35m

I have the SDA 2A's now but i'm thinking about upgrading to the big SRS's. I'm in houston.

Shizelbs

I would frequent the forum here. I got my SRS from a listing here.

candyliquor35m

Did you get them at a reasonable price which from what I've seen is not more than $1500. I'm very satisfied with my SDA 2A's except when I try to rock to something very loud like Kansas or Journey using a Carver 375 wpc TFM-45, the speakers appear to shut down because I am overloading them. I've only pushed them past their breaking point a couple of times because I don't want to damage them. I'm open to any suggestions anyone has as far as matching my amp up with any of the vintage SDA's out there.

F1nut

Exactly what happens when they appear to shut down? What pre amp are you using and is your volume control past halfway when this happens?

candyliquor35m

I'm a amatuer here so pardon my untechnical language. I'm using a sony ta-e1000esd pre-amp which is a surround sound pre-amp but I turn the surround sound off when I'm listening to music. The front speaker output is attenuated back so even though the master control volume is maxed out, I'm not giving the speakers all the power I have.

When it happens, the speakers keep playing but at a reduced volume which I've always assumed that they were doing to prevent damaging themselves.

F1nut

Ok, I'm not familiar with that pre amp, but I am sure that regardless of the attenuated front speaker output you should not have the master volume control maxed out. It should not go past halfway. What's happening is the amp is clipping and in turn causing the tweeter protection to kick in.

candyliquor35m

Good point. I hadn't really thought about the amp clipping since I didn't think I was driving it that hard since it is a 375 wpc amp. I checked and I have the pre-amp notched down 10dB. I guess I need to think about adding a second amp and running them mono at 1000 wpc but I then I run the risk of tripping the thermal protective device in the speaker don't I?

nadams

I think your amp is fine. Look at your preamp for the problem. You never want to have the volume turned up all the way, regardless of what kind of output volume you're getting from the speakers. At 100% volume, your preamp is putting out a distorted signal, which could be the cause of your problems.

Also, where do you ahve the gain set on your amp?

PS- you're already tripping the thermal protection....

fireshoes

I might be wrong here, but I think the preamp output was clipping, and the Carver amp is detecting that and engaging its anti-clipping circuitry. Turning down the preamp should do the trick.

George Grand

TFM-45 doesn't have gain controls. Just set the -10db switch on the preamp back to the normal position, and see if your tweeter protection starts kicking in again.

Then go to the library and get some books on understanding audio equipment.

I don't think I have ever heard of a preamp "clipping" before Fireshoes. Power amps clip, not preamps.

Nadams, why shouldn't a preamp output control be turned up all the way, IF you've got an amplifier with input level controls (which he doesn't) that you can keep turned way down? Not the preferred way to operate a preamp but it can be done.

A good way to operate with an amp that has input level controls is to set the preamp output level to about the 12:00 position and then advance the power amps input level controls up till satisfactory SPL's are reached.

George Grand (of the Jersey Grands)

Emlyn

Originally posted by candyliquor35m
I guess I need to think about adding a second amp and running them mono at 1000 wpc but I then I run the risk of tripping the thermal protective device in the speaker don't I?

You'll do much worse than that. Whatever you do, do not hook up non-common ground amps (i.e. mono or bridged amps) with SDA-2As with the blade/blade SDA interconnect cable in place. Do a search for "common ground" in the forum.

candyliquor35m

Thanks for all the great ideas. I've stuck with the Sony pre-amp because I can connect it to my sony cdp-p910 cd player using the direct digital sync (glass cable but I bought the plastic one 10 years ago because it seemed $100 was pricey for a cable). I don't know how important each piece of my ancient system is but the clarity and richness I hear, I've never heard anywhere else. I'm hoping to improve it somehow slowly and carefully.

Tour2ma

cl35m,

First welcome to the Forum... always good to see another Houston area member come on board.

With the sound "attenuated" rather than shut down altogether, it sounds like the speakers' polyswitches are opening rather than the amp protection kicking in. My left channel SRS did the same on a Carver M-1.5t that I never saw clip. When a polyswitch does it's thing, just a dulling of the sound occurs and after the polyswitch cools off a bit, the sound comes back.

It is possible that your polyswitches are "tired" and open prematurely. Contact Ken at polk Customer Service, and he'll send you a fresh pair... gratis.

While it is also possible that your pre-amp is clipping (yup... being a voltage step up device they can, just as amps do), I think it more likely that you are simply asking too much current from the TFM-45 during your wild periods. The SDA 2's are a 4-ohm nominal load, but dip lower when driven. How hot does the 45 get?

Stepping up to SRS's is not necessarily a solution. For me the Sunfire acquisition was the solution... quite a bit more current available.

But if you want SRS's (and why not)... historical prices have been as high as $2000, with a norm of $1600. The lower prices ($1200 and such) are a much more recent trend. So I would not consider $1500 to be a max for a nice pair.

candyliquor35m

Tour2ma,

More great info. and nice to have a local to confer with. I set the digital attenuator back to 0dB and cranked the pre-amp to 1/2 with no problem and the meters on the amp never go past 50 watts. Is that because the polks are so efficient?

The tweeter on the right channel shuts down when I turn the volume to 3/4 and the amp is almost hitting 180 watts on the loud bass thumps. I'm going to order the polyswitches and the silk tweeters this week. Thanks.

F1nut

Cranking any volume control past halfway is going to cause distortion and other problems. Turn it down!

nadams

^
||

That's why, George. Regardless, it sounds like this person is having some other issues, as well.

madmax

I think his poly fuses are just tripping. My old SRS's do that all the time.
madmax

Tour2ma

It's the Poly's, but they are opening for a reason...

cl,
As F1 and others are saying, you're just pushing too hard.

We haven't talked about your music of choice, so I'll assume rock since that's what "we" tend to push the volume on in an effort to attain concert levels.

Rock has low dynamics, and so presents the highest continuous duty to amps. 3/4 volume is just asking for clipping. 12 o'clock as a norm max, with 1 o'clock as an absolute max and then only for a track or so...

Others may correct me here, but I do not believe that analog meters, like those in your 45, reflect peak watts... more like average. So your 180 watt peaks may in fact have leading edge transients that are double that... And while you have a 375wpc amp with better than 2 dB headroom, into a 4 ohm load (or less) you're simply running out of current and the amp starts acting like a dc source and the Poly's overheat and open.

I don't think new poly's and/or tweeters are going to allow you to operate at the dB levels you seem determined to achieve. Ditto for SRS's and even more amp (do note Emlyn's above caution on trying bridged mono's... it's a recipe for disaster with 2A's).

What you can try with what you have is a smaller room and/ or a closer listening postion.

At 92 dB the efficiency of your 2's is just a little above average.

candyliquor35m

HELP, well first thanks for all the great comments. I'm reading my owner's manual for my Carver tfm-45 which I had decided to try to buy another one so I can use them in mono and the manual says to use speakers of 8-ohm or higher impedance for mono operation. Dumb question I know but does this mean I can't use my Polks (sda-2a) and the amps in mono? Does this mean the carver isn't a common ground amp that everyone's been warning me about?

candyliquor35m

Just a follow up here. My sda 2a's have the pin/blade IC. I've been reading the past discussions about using 2 channels amps in mono with the polk sda's and the conclusion seems to inconclusive. Is there anyway I can be sure before I buy a 2nd tfm-45?

TroyD

If I'm not mistaken, the 2A's can't even employ the A1 interface, right??

That said, in stereo operation the TFM-45 is indeed common ground. Obviously if you use two bridged to mono, they aren't common ground.

K, I do believe that the SDA's are 6 ohm impedence. IF you were to bridge a pair of TFM-45's AND had a pair of SDA's that could handle an A1 interface, I have no doubt that the amps would be stable enough to work without issue. OK, THAT said, I'm of the opinion that ONE TFM-45 in stereo mode is all the power that you require for a pair of SDA 2A's. I'm running my SDA 2.3tl's with a TFM-45 and at full tilt (re: as loud as I can take it) the TFM-45 doesn't break a sweat.

IMO, I wouldn't worry about it.

BDT

F1nut

Regardless of anything else, your 2A's are 4 ohm speakers and the Carver's, in a bridged mode, are only rated to drive 8 ohm loads. That means you can't do it.

Edit: Troy is right, the 2A's are not designed for the AI-1 interface either.

Tour2ma

Pin-blade? On 2A's?

I think we're talking 2B's here...

ohskigod

i use to use a pro logic preamp in my 2 channel system (Rotel RSP960) with this preamp, i found that sometimes you needed to go past halfway to acheive louder listening levels, i never had clipping or shut down issues, but i was never comfortable with having to do so to listen at a level i wanted at the time. I got a dedicated 2 channel premp (Parasound) and never looked back. I think your preamp is the problem. cant specify exact reasons why, but getting my pro logic pre out of the mix did wonders for my 2 channel system. you definitly want to go dedicated 2 channel with those SDA's to hear what they can really do.

just my .02

candyliquor35m

Due to everyone's great posts, I realize I can't use the Carvers as monoblocks with the 2a's. It would have saved me quite a few hundred or maybe a grand versus buying another amp that will give me the 1000 wpc into 8 ohms that the carvers would have.

All this came about because I am hoping to upgrade to the big SRS's and I figure I will need more power to drive them. Does a bigger speaker (srs vs 2a) mean more sound using the same amount of power or does a bigger speaker mean less sound via the same power? I've never listened to a srs so I don't know what to expect.

My 2a's have the 1 tweeter and 2 drivers and the 12" passive that I've seen in all the pictures floating around including the manual or brochure I received when I bought them used 10+ years ago amazingly only 2 miles from where I live. I've looked a couple times already and they do have the pin/blade IC.

oops I just took one of my drivers out and it said 2B, is that a pleasant surprise or a non-issue? what is a 2BV, mine looks identical to it with the speaker elevated kind of on a base 4-5".

F1nut

Then Tour is correct, you do not have 2A's, you must have 2B's. The 2B's are nominal 6 ohm speakers. The SRS's are nominal 4 ohm speakers and you can not use bridged amps with them, period. If you're not happy with the volume levels using a 375 wpc amp, you need more efficient speakers. I run 475 wpc at 6 ohms and have peaked at 117dB, effing loud!!! The SDA's (not CRS's) maximum SPL, depending on model is between 120dB to 125dB. I know that no matter how much power you feed the 2B's, you'll never get that high and I seriously doubt you could do it with the SRS's.


Get rid of that Sony pre amp and get a real one. In fact, get a tubed pre amp, you'll thank me 'till your dying day. Next thing, no make that the first thing you should really do is go the the library and check out all the books you can on hifi audio.

Edit: I see while I was typing that you've discovered they are 2B's.

Tour2ma

Above is true, F1's rig can crank louder than I can listen... so very long anyway, but his amp has more current capability than a TFM-45.

Pin-Blade 2B's do bring the potential use of the AI-1 SDA IC back into the picture and thus the use of twin Carvers bridged to mono.

May be wrong here... I know Carver only listed a rating at 8-ohm for bridging any of their amps, but I have never taken that as they are not stable at lower loads. We know GG runs twin bridged on his CA's with no issues.

Bigger does not necesarily mean more or less efficient. However, in this case the SRS's are 3 dB more efficient than the 2B's (93 vs. ~90 dB).

Of course as has been pointed out, the SRS's remove the twin bridged option, but you instead can horizontally bi-amp them.

cl35m,
If you want to try a different pre-amp (or two) and amp (or two), shoot me a PM with your number and we can arrange a meet at your place...

candyliquor35m

ok if this thread goes to 2 pages, I'm out of here. F1 I believe you as far as my pre-amp but the Sony ES line is alot better than anything you normally get from sony. I have gotten so used to its theater soundfield setting out of 10 soundfields available not to mention the couple of extra bars of treble that I keep the parametric eq set to.

I am so limited spacewise in this 1100 sq. ft. house that my home theater and 2 channel systems are one in the same just by turning the surround sound off for 2 channel.

Here's the rest of my rinky dink system:

Rear: polk crs's on stands via carver m1.0t
Center: jbl 4311b via sony n110 mono
Sub: jbl 4311b via nad 2100 mono
Pre-amp & surround sound: sony ta-e1000esd
CD: sony cdp-c910

Tour that's an offer I can't refuse, I'm in Katy.

btw I rarely listen to rock. if anyone sees these cd's, I recommend a listen ie my favorites:

Pat Metheny - Letters from home
Courtney Pine - Closer to home
Kenny G - Breathless

F1nut

Originally posted by candyliquor35m
ok if this thread goes to 2 pages, I'm out of here.

LOL....if it gets to 3, then I'm leaving too.

I'm very familiar with Sony ES gear and it's definitely many cuts above their regular line, but there are tons of better pre amps out there, some even have HT pass thru and none of them have that nasty DSP or tone controls. Anyway, it's nice of Tour to make his offer, I think it'll open your eyes......and ears.

It's true that GG runs bridged Carver's on his Plats, but they are 8 ohm nominal. I think you could probably get away with running bridged Carver's with the 2B's, but why would you? It's way more power than they can handle.