Emotiva RSP-1 and RPA-1 sound bad with Polk SDA-1C?

[thestevest]

I recently picked up an Emotiva RSP-1 Pre-Amp and RPA-1 Power-Amp combo to give some more drive to my polk SDA 1-C's(50-500wpc). (Previously powered by a restored SX-9000 at 80wpc into 4 ohms)



I got them home and hooked them up to my SDA-1Cs and was immediately dissapointed... It was like someone had thrown a sheet over the speakers. The bass was great, but highs and mids sounded quiet and muddled. Even with the treble control turned to max it didn't have that "sparkle" on the high-end that you expect. I thought it might be the pre-amp so I switched the RSP-1 out for my SX-9000 using the pre-out lines, but it still sounded the same.



The RPA-1 had fantastic reviews and is rated at 350wpc into a 4 ohm load. Interior construction is basically dual Monoblocks, with each channel having it's own high-current toroidal transformer. It is also a common-ground amp (required for SDA speakers)



The build quality and finish of the Emotivas is amazing, hefty units with beautiful finishing and presence. I demo'd them with a pair of 4 ohm DIY speakers and they sounded amazing, crisp, punchy, and powerful.



Has anyone else experienced this before? Do some speakers and amps just not play well together? For now I've gone back to using my SX-9000 to power the Polks and to my ears it sounds much better, even with the lower power.



Any Ideas? I know this is in general a very favored amp/preamp, but I'm not sure what it is.

[KeithL]

It is true that some amplifiers do have a very subtle sound character of their own.

(What we're talking about here is a very small amount of coloration... two "absolutely perfect" amplifiers would sound identical).

To be quite honest most modern power amps, including ours, are quite neutral in sound.

While it is true that some few amps may have trouble driving some few speakers - this is rarely a problem.

It seems more likely that your old SX-9000 had a bit of coloration...

(Many older amplifiers had relatively low damping factors and relatively high levels of distortion compared to modern ones.)

And that this coloration happened to complement the sound of those speakers in that room...

(Perhaps it was a bit forward in the midrange, or had slightly elevated second harmonic distortion, both of which can make things sound "clearer".)

And that, lacking this, the RPA-1 now sounds "quiet" or "unexciting".

It's also possible that you may find you like the way they sound now better once you get used to it.

Mar 23, 2021 11:28:08 GMT -5 thestevest said:

I recently picked up an Emotiva RSP-1 Pre-Amp and RPA-1 Power-Amp combo to give some more drive to my polk SDA 1-C's(50-500wpc). (Previously powered by a restored SX-9000 at 80wpc into 4 ohms)



I got them home and hooked them up to my SDA-1Cs and was immediately dissapointed... It was like someone had thrown a sheet over the speakers. The bass was great, but highs and mids sounded quiet and muddled. Even with the treble control turned to max it didn't have that "sparkle" on the high-end that you expect. I thought it might be the pre-amp so I switched the RSP-1 out for my SX-9000 using the pre-out lines, but it still sounded the same.



The RPA-1 had fantastic reviews and is rated at 350wpc into a 4 ohm load. Interior construction is basically dual Monoblocks, with each channel having it's own high-current toroidal transformer. It is also a common-ground amp (required for SDA speakers)



The build quality and finish of the Emotivas is amazing, hefty units with beautiful finishing and presence. I demo'd them with a pair of 4 ohm DIY speakers and they sounded amazing, crisp, punchy, and powerful.



Has anyone else experienced this before? Do some speakers and amps just not play well together? For now I've gone back to using my SX-9000 to power the Polks and to my ears it sounds much better, even with the lower power.



Any Ideas? I know this is in general a very favored amp/preamp, but I'm not sure what it is.