SDA 2A Set up advice

e_just

Hey Gang
I'm thinking about buying a pair of SDA-2As locally and was hoping someone with experience can help me out. Is there a consensus of how far apart they need to be placed to sound best? I'm working with about 7-8 feet. Would that be enough for them to image properly? I woul be powering them with an Onkyo M504.
Thanks
Eric

e_just

Thanks everyone for your in depth replies. From what I'm reading, the SDAs won't work in my room. There has been a pair locally (Pittsburgh) on FB marketplace for $325 and I was thinking of snagging them but after reading, I'm gonna pass. I guess I'll make do with my Monitor 7s and 5s.
Eric

Gardenstater

This manual includes coverage for the SDA 2B; the model version that is just after yours. Yours is 3rd Generation. 2B is Fourth Generation. Also read the SDA Handbook. You need sufficient space to each side (outside) of the speakers as well and you don't want to toe them in. SDA Handbook says: "Note that SDA's require at least 3 feet of distance from the side walls and 6 to 8 feet of spacing between them for optimum performance. This means the speakers must be placed along a wall at least 15 to 18 feet in length, depending on the speaker size. Reflections from nearby walls can negatively affect imaging. The listening position must be equal to or greater than the distance between the speakers".

There was also a review in Stereo Review where he found they can dip as low as 3.5 ohms impedance between 100 and 130 Hz. Also he got a lower sensitivity than Polk. He measured 88dB where Polk said 92dB. I have heard forum members say these speakers have fried some very good amplifiers.

They raised the impedance in the 2B which should probably tell us something. They also went with MW6503 which is a tighter sounding driver with lower Qts than the MW6510 in the 2A.

https://polksda.com/pdfs/SDA1C.pdf

https://www.vr3mods.net/_files/ugd/932cf5_6f335b7f8e3b4ba39613def7f4b3f83e.pdf

Review on p. 52:

https://www.worldradiohistory.com/Archive-All-Audio/Archive-HiFI-Stereo/80s/HiFi-Stereo-Review-1986-12.pdf

aprazer402

The 2A's are four ohm speakers. The Onkyo M504 should be okay to use with them.

They have two crossover boards per speaker.

They can be made sound better than stock but it's pricey to do so.

The later 2B model is a much better choice.

Emlyn

Optimal spacing between the cabinets depends on how far away your ears will be from them and how far away the speakers will be from side walls. Generally speaking for most rooms 6 to 8 feet apart is ok from the inside edge of each cabinet. That would be for a front wall of between 12 feet minimum and 14 feet or more. Fine tune distances by ears to get the best imaging.

invalid

I have owned these speakers since 1987, and I can tell you they are very hard on amplifiers. I smoked many receivers and amplifiers with these speakers, my adcom GFA 555 used to overheat and shut down whichever channel was overheating, I had a carver receiver actually burst into flames. If you don't listen too loud you will probably be fine. I drive them currently with a Krell ksa 300s amplifier or a hybrid amplifier that's capable of driving a 2ohm load. I rebuilt the crossovers about 8 years ago and now the impedance dips are even lower than a stock pair, because of the lower DCR inductors I used.