SDA 1B Questions...

Texas42

Hi,
I'm looking at buying my first set of vintage Polk SDA speakers and have an opportunity to purchase a pair of SDA 1bs. Any comments on their relative sound/value? Also, I had read on another board that in order for the SDA process to have an effect the amplifier you use must have a common ground (I'm guessing this means a 3 pronged power plug?). Is this correct? The amp I'd be using this with is a vintage, completely modified Pioneer Spec 4 Amp which has a two pronged (old style) plug. However, the Pioneer also has a terminal on the back for a ground wire to be attached and I'm (again) assuming I could run a copper wire from that to the metal chassis of the amp or another piece of equipment and that could accomplish the same thing?

Thanks for any ideas/suggestions about these speakers and also appreciate any info on possible incompatibility issues.

Ricardo

Hi and Welcome to the forum.

My first pair of SDA's were 1B's; they are great sounding speakers and if you can buy them cheap you are in for a treat; anything below $400 IMO means cheap, if they are in good overall condition.

Common ground amp means that the negative outputs of each channel are common ground; in other words, if you measure resistance between them you should get 0 ohms.

What's the power of that amp?

Texas42

Oh, the specs on the Pioneer Spec 4 is 200 WPC into 8 ohms, if that makes a difference...

Ricardo

That will be more than enough.

Texas42

HTRookie, I like the equipment in your signature. I have the AES-25 Superamp in my main system and was considering the AES AE-3 as my preamp. Owned the Carvers at one time as well, very smooth ribbon. How would I determine if my Pioneer is common ground? Should it say it in the Operating manual or schematic? If not I have a multimeter but not sure exactly how I would measure it....

Ricardo

Grab that multimeter and turn the dial to ohms; with the amp off, measure between the two negative binding posts (speaker output); if you read 0, you're good to go.

The basic AES-AE3 is not that good (I've heard); the DJH signature version is VERY good. At least i am very happy with it.

Refefer

Hey, I own a pair right now. An excellent purchase if I do say so myself. What's in your main rig? I'll be honest, You very well might be changing out speakers once you get some SDA going on, there's just nothing like it.

Texas42

If I did it correctly, the reading is 000.3. I turned the dial to Ohms, and used the 'com' and ohm outputs to touch both negative speaker terminals on the back of the amp simulatneously.

Refefer: I have a shot at buying these, the guy want $425.00 for them but states they are in very good condition. Waiting for pics now. My main system is a pair of modified Klipsch LaScalas, a Cary AES 25 Superamp (KT 88 tubes); a Transcedent Audio Grounded Grid tube preamp, and an Audio Analogue Paganini CD player. The Polks would be in another room with some vintage modified Pioneer Grear, where I am currently running a pair of HPM-1500 speakers and a Pioneer Spec 1 Preamp and Spec 4 amp.

Texas42

Referer: Also, is there anything in particular I should look at on SDA 1Bs before I buy? I'm guessing general condition of the cabinet, drivers, driver surrounds, leaking ferrifluid, etc. We would be meeting halfway with a simple exchange but won't be able to audition prior to buying....

Refefer

Hmm, LaScalas... big into vintage? Those are a decent pair of speakers. I could never get too big into klipsch due to my ears tendency to hate horns, but the second you feel that kick drum on a 100db sensitivity speaker... wow. I was also using SS gear, so I have no idea how much tubes would have softened the top end.

Texas42 wrote:

Referer: Also, is there anything in particular I should look at on SDA 1Bs before I buy? I'm guessing general condition of the cabinet, drivers, driver surrounds, leaking ferrifluid, etc. We would be meeting halfway with a simple exchange but won't be able to audition prior to buying....

$425 for mint 1B's isn't a bad deal. Does he have the crossover cable? That's the most important question you should ask. If he doesn't have it, you can make another one(instructions available on this site) , but it's a lot easier if he has it.

If you're a tweaker, these are also great speakers to pick up. Crossover, driver, and grill upgrades, have yielded great improvements of already great sounding speakers.

Things to check (and I hope others will chime in): Make sure the drivers aren't loaded with dust. Very lightly push in the passive radiator (the 12" one at the bottom) and make sure the 4 midrangers move out as well (these are sealed boxes, so they should).

Honestly, if one of the tweeters are busted, you can still get them from Polk and more importantly get their upgrade which most of us have purchased.

Ricardo

$425 would be a good price if they are in really mint condition, with all good drivers, interconenct, etc. You can check the drivers by slightly pushing on the passive radiator to make drivers move; you should not hear any scratchy noise. This does not guarantee that they are perfect, but will rule out major damage.

You can also take your multimeter and perform some measures between binding posts and interconnect terminals; there are some standard values that you should be getting. There's an SDA check guide posted somewhere that will give you the expected values.

If you could have the owner perform all these checks beforehand and tell him that you won't get them if there are issues, maybe you can save some time in case they are not good. Pictures will tell you cosmetics.

Good luck.

Refefer

Oh, and welcome to the Forum!

Ricardo

Here's the check sheet

Texas42

Thanks for the tips...he told me he does have the interconnect cable. And I misspoke earlier, his email related they are in 'good' condition so will have to see just how good.

rromeo923

I have a pair of SDA 1C's that I would like to ck the interconnect cable w/a multimeter. I just read the check sheet and it does not seem to have the readings for the 1c.

Any suggestions?