Polk SDA 2A with Scott LK 48 Amp

[Lauren H]

I recently purchased a Scottkit LK 48 and I wanted to make sure I can use it with my Polk SDA 2A's. I am pretty sure I can but would there be any downfalls?

 

[Johnny_Law]

The SDA circuit needs a common-ground amp in order to operate correctly. The Scott LK 48's 4ohm outputs look to be tied together, so I wonder if you should connect your negative leads to those 4ohm taps. I admit I've never run any SDAs with any tube amps - maybe someone who has done so can confirm.

 

[Lauren H]

I’ve attached a schematic if that helps of the LK 48. I don’t have a multimeter unfortunately.

 

[Johnny_Law]

That's really interesting - the schematic I have (maybe it's an LK48b?) shows the 4ohm taps tied together, not the 0 taps like your schematic shows.

This schematic also has a center channel tap - does yours have a center channel?

Dang a multimeter would really come in handy to figure out which taps are tied together.

 

[Lauren H]

That's really interesting - the schematic I have (maybe it's an LK48b?) shows the 4ohm taps tied together, not the 0 taps like your schematic shows.

This schematic also has a center channel tap - does yours have a center channel?

Dang a multimeter would really come in handy to figure out which taps are tied together.

View attachment 1615124

There is a center channel on mine so maybe I have the lk 48b? Might have sent wrong schematic.

 

[Johnny_Law]

Hmm, yeah there's no center channel on that schematic you attached, so seems like it maybe is a 48b. But it would be best to verify with a multimeter ... maybe now's the time to get one?

 

[Lauren H]

Hmm, yeah there's no center channel on that schematic you attached, so seems like it maybe is a 48b. But it would be best to verify with a multimeter ... maybe now's the time to get one?

Got a multimeter. On the 200 ohm setting when touching the two grounds it’s reading 1.5. Guessing it’s an uncommon then?

 

[Johnny_Law]

What does it read between the 4 ohm taps?

 

[Lauren H]

If I put the terminals to both 4ohm screws it reads .06 ohms

 

[Johnny_Law]

That certainly seems to support the schematic I posted above (the 48b schematic), showing the actual common ground to be between the 4 ohm taps... some research has turned up other commentary to that effect, e.g. "KennethSwauger" comment in this thread.

(I wonder if the 0.06ohms is the resistance of your multimeter leads - as the schematic shows the 4 ohm taps to be connected directly.)

So, because it seems like your 4 ohm taps are the common ground, I would tentatively endorse running the 4ohm taps to your negative terminals on the SDAs. But if I were you, I would wait until someone else agrees with or refutes my hypothesis! Would hate to damage anything.

I believe Jesse @F1nut has run SDAs on tube amps before, maybe he can chime in.

 

[Lauren H]

That certainly seems to support the schematic I posted above (the 48b schematic), showing the actual common ground to be between the 4 ohm taps... some research has turned up other commentary to that effect, e.g. "KennethSwauger" comment in this thread.

(I wonder if the 0.06ohms is the resistance of your multimeter leads - as the schematic shows the 4 ohm taps to be connected directly.)

So, because it seems like your 4 ohm taps are the common ground, I would tentatively endorse running the 4ohm taps to your negative terminals on the SDAs. But if I were you, I would wait until someone else agrees with or refutes my hypothesis! Would hate to damage anything.

I believe Jesse @F1nut has run SDAs on tube amps before, maybe he can chime in.

Thanks for all of the help!!

 

[Dswankey]

I believe Jesse @F1nut has run SDAs on tube amps before, maybe he can chime in.

He did on her other thread, which maybe she forgot about seeing has she hasn't replied to it

.......... even if it is common ground your tube integrated does not have enough juice to properly drive the SDA's.

https://www.audiokarma.org/forums/index.php?threads/scottkit-lk-48-with-polk-audio-sda-2a.883598/