Prilaluna Prologue Premium with KEF LS50

Sorry for double post

Change the tubes. Stock ones are not great

The stock tubes may be doing the sound any favors. Lots of discussion about this, do a search. In addition Kevin Deal has tubes for rolling for sale, you can ask him for help with his amp.

Try the 8 ohm taps.

Turns out it is on the 4 ohm taps. Ant recommendations on tubes?

Change the tubes. Stock ones are not great

Maybe different and/or better tubes?

It's used but I am not sure how old. Pretty sure it's broke in.

If the amp is brand new, it may not be broken in yet.

Thank you both. I'll try the 4ohm taps. I want to love this amp.

Ben

It could be an artifact of using teh PL tube amp with the KEF ls50. The KEFs are not tube amp friendly. Look for measurements on teh KEFs. Impedance peaks and dips and/or pahse angles at various frequencies with the KEFs might produce teh results you hear. I would only use a high current SS amp with those speakers for teh best results.

I ran a friends LS50s off TAD hibachi amps I had that are designed to emulate a tube amp. The results were much as you describe. Same speakers then sounded great 15 minutes later running off high power high current Bel canto ref1000m monoblocks (Class D SS).

So I suspect teh problem is with the combo of amp and speakers and not inherent to either one alone necessarily.

If you are presently using the amp's 8 ohm taps, given the upper mid-range impedance peak of the speaker, as shown here, going to the 4 ohms taps will probably reduce the peakiness of the upper midrange. Although it may also have other sonic effects which you may or may not prefer.

Regards,
-- Al