Polk SDA 2 compatibility with Amplifier
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Hello Folks,
I started using the SDA 2a couple of months back. I like them. The question I have is about what it says on back i.e. Use Common Ground Amplifiers only.
So, Can someone please tell me if Pioneer SX-1080 and Marantz 2220B fit that criteria; and are safe/OK to be used with SDA 2s?
I started using the SDA 2a couple of months back. I like them. The question I have is about what it says on back i.e. Use Common Ground Amplifiers only.
So, Can someone please tell me if Pioneer SX-1080 and Marantz 2220B fit that criteria; and are safe/OK to be used with SDA 2s?
Answers
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Most 99% receivers are common ground
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They should both be common ground. However I dont think either will have the current to truly "hear" the speakers.
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I would definitely stick to the Pioneer because at least they rate it at 4 Ohms as 150 WPC with no more than 0.05% distortion. That Marantz doesn't give the rating at 4 Ohms and is only 20 WPC into 8 Ohms at 0.5% thd. Also the Pioneer will give you much more headroom. Those SDA 2A can dip as low as 3.5 Ohms between 100 and 130 Hz, according to the review from Dec 1986 in Stereo Review.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
@jacobmeyerammo Even Pioneer 1080 won’t have enough current for speakers? That is supposedly quite powerful receiver!!
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SDA 2a starts at 4ohm and drops very low into 3ohm territory. They will cook receivers.
Ask me how I know.... -
Yes...they WILL cook recivers....my first set of SDAs I thought there was something wrong with them...I hooked them up to three different receivers and they would either cut out completely or the receiver would go into "protect" mode ... After much research and fiddling on the forum here went with a Carver TFM25 amp. The difference....even at low volume is astounding
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What receivers did you guys cook? Not challenging, pure curiosity.
Her Pioneer seems to have a pretty respectable power supply with a very large transformer and two 22,000 uF filter capacitors and the receiver weighs in at 47 lbs.
Pretty respectable sounding protection circuit IC that controls relays on the output:
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I completely cooked an Onkyo TX-SR701. As well as a Mitsubishi MA-5200 stand alone amp before I picked up the Carver
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Denon 3805
Yamaha high end DSP a1 IIRC.
Trust me if you like it loud forgetabout it.
Even at low volumes my 3805 would get very hot.
The blade/Blade models send signal on both blades. Outputs need to be robust and most receivers are not known for robust outputs. The sda2a is a half a step away from a direct short.
Just be very careful is all. -
@pitdogg2 Thank you. They do sound good with my Pioneer. Out of curiosity.....what are the best recommended Receivers (2-3) for SDAs?
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Forget receivers, look at integrated amps or separates.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Forget receivers, look at integrated amps or separates.
I agree. You will take those SDA's to the next level. -
What receivers did you guys cook? Not challenging, pure curiosity
I burnt up a 130 watt carver receiver in 1988 with my newly acquired sda2A's, when I say burnt I mean burnt it shot a 2' flame out of the top cover. A Sony receiver my friend brought over was les spectacular just stopped working and smelled like burnt electronics. The carver worked for a few months before it flamed out, but the Sony only played a couple notes before it gave up. -
Has anyone had a receiver that was rated by the mfg. for continuous power output into 4 Ohms get toasted or fail? At least some of the above that I could find info. on and I checked specifically stated 6 ohms min. Is the SDA 2A a reactive or easier 4 Ohm nom. impedance? I know it can dip down to 3.5 between 100 and 130Hz George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
In my experience most receivers will restrict current on 4ohm loads. Those speakers do need good current.
I believe they were 90db or so efficient. -
What I've noticed about the sda2A's is they seem to be harder on amps/receivers than most typical 4ohm speakers, could have something to do with the sda circuit just a guess.
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What I've noticed about the sda2A's is they seem to be harder on amps/receivers than most typical 4ohm speakers, could have something to do with the sda circuit just a guess.
I can agree with this. -
I had a Realistic SCR-4500 Cassiever (*remember Radio Shack??*) that would play just fine on my SDA-1B's until I turned up the volume. Then I would hear a loud "clack" from the receiver as the protection circuit disconnected the amp and then silence until I turned the volume back down and the amp would come back in. I wound up buying an NAD 7175pe receiver. I remember a friend had a Luxman high current receiver that drove the heck out of those 1b's as well.
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I was curious so I found the Polk SDA 2A manual and they surprisingly say it is a very easy load, being mostly resistance however they do say what you guys are saying and the Stereo Review article said, that the load does vary dynamically with the balance of signals between the two channels, by which they must mean that the more stereo differentiation, the more the load seen by the amp will vary. They say to avoid amps that are not comfortable driving low impedances and that have excessive current limiting, as you guys state. The question is how do you weed out an amplifier or a receiver that has a continuous power rating into 4 Ohms that is higher than its rating into 8 Ohms? How do you decide which ones have "excessive current limiting"? Should you say, well the 4 ohm rating should be at least 25% higher than the 8 ohm (or some other number)? The FTC and the manufacturers do not make that easy by any means. I know you can look at the size of the filter capacitors and the transformer and the weight of the amplifier and the quality and quantity of output transistors, but that's all pretty inside stuff that the average buyer and even audiophile doesn't really know how to evaluate.
Not trying to be argumentative, really curious George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Gardenstater wrote: »I was curious so I found the Polk SDA 2A manual and they surprisingly say it is a very easy load, being mostly resistance however they do say what you guys are saying and the Stereo Review article said, that the load does vary dynamically with the balance of signals between the two channels, by which they must mean that the more stereo differentiation, the more the load seen by the amp will vary. They say to avoid amps that are not comfortable driving low impedances and that have excessive current limiting, as you guys state. The question is how do you weed out an amplifier or a receiver that has a continuous power rating into 4 Ohms that is higher than its rating into 8 Ohms? How do you decide which ones have "excessive current limiting"? Should you say, well the 4 ohm rating should be at least 25% higher than the 8 ohm (or some other number)? The FTC and the manufacturers do not make that easy by any means. I know you can look at the size of the filter capacitors and the transformer and the weight of the amplifier and the quality and quantity of output transistors, but that's all pretty inside stuff that the average buyer and even audiophile doesn't really know how to evaluate.
Not trying to be argumentative, really curious
An amp or receiver that is high current (the two that I mentioned above are good examples) will always work. -
Sometimes even amps that should be able to drive them easily will trip their protection circuit, for instance back in the late 80's I was shopping for an amp for my 2A's I demoed a demon 200 watt amp that should have easily powered them but at high spl's it would trip the protection circuit, so I bought the adcom gfa555 instead.
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You could just purchase an amp that is rated for down to a 2ohm load then you are safe for sure even if you change the bass inductor, to a lower resistance inductor.
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honestaquarian (and others) - I guess what I'm saying is how does the average person evaluate a potential amp/receiver to be purchased as far as whether it is "high current" as you put it?
For example, my ol' Crown D150 is rated at *typically* 100 WPC into 8ohms, 180 WPC into 4 ohms. Her receiver is 120 WPC into 8 ohms and 150 WPC into 4 ohms. Which would be better? What else do you have to look at that is quantifiable?
Is it just a matter of the WPC at 4 ohms and whether it is higher in one amp than the other, or is it also a % increase in WPC of 4ohm rating vs 8 ohms or something else?
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
If the amp has a doubling down of power as the resistance if halved you should have no problems, of course no amp can really do this but the ones that are rated as such come close.
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If the amp has a doubling down of power as the resistance if halved you should have no problems, of course no amp can really do this but the ones that are rated as such come close.
I never heard that before. Do you have any data to support that?
Lumin X1 file player, Westminster Labs interconnect cable
Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
Magico S5 MKII Mcast Rose speakers; SPOD spikes
Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
Shunyata Sigma XLR analog ICs, Sigma speaker cables
Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables
Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
Three 20 amp circuits. -
never heard that before. Do you have any data to support that?
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It is simple math. If an amplifier is not current limited, it will supply twice as much power into a load that is half the impedance, i.e. twice the power into a 4 ohm load compared to an 8 ohm load. That is essentially the definition of not current limited. The amount of absolute power also counts, e.g. 200 watts into 4 ohms is obviously better than 100 watts.SONY VPL-VW385ES, Da-Lite 92" 0.9 HD progressive 16x9 screen, Apple TV 4K, Oppo UDP 203, Anthem AVM 60, D-Sonic 4000 (800x3, 400x4) for bed layer, 2 Crown XLS 1002 (225x4) for Atmos; Speakers: Polk LSiM 705s, 703 front, 4 702F/X surround, 4 Polk TL3 (Atmos), Velodyne DD15 Subwoofer.
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If you look at measurements from stereophile or any 3rd party you will find that the 8ohm measurements are underrated, when you have the actual 8ohm measurements it will not be double.
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Gardenstater wrote: »honestaquarian (and others) - I guess what I'm saying is how does the average person evaluate a potential amp/receiver to be purchased as far as whether it is "high current" as you put it?
For example, my ol' Crown D150 is rated at *typically* 100 WPC into 8ohms, 180 WPC into 4 ohms. Her receiver is 120 WPC into 8 ohms and 150 WPC into 4 ohms. Which would be better? What else do you have to look at that is quantifiable?
Is it just a matter of the WPC at 4 ohms and whether it is higher in one amp than the other, or is it also a % increase in WPC of 4ohm rating vs 8 ohms or something else?
Basically what it comes down to is the old addage that you must buy the electronics to suit the speakers (*and NOT the other way around*) as I found out in the late eighties when I bought my first SDA's. High current amps ain't cheap!
Remember Luxman was considered an entry level high end brand.
NAD the same.
Harman Kardon receivers are also high current. -
Her receiver is 120 WPC into 8 ohms and 150 WPC into 4 ohms. Which would be better? What else do you have to look at that is quantifiable?
That one has no balls. Forget about it!
What I'm saying is for some frequencies you will use up all it has to give and the rest is a clipped signal.
If an amp can get close to double as you go down you "should" be ok.
