PrimaLuna DiaLogue Premium – Tube Rolling – KT88 – Mini Review
Comparing the standard EL34 tubes to KT88 tubes
Review samples supplied by A Tube High Fidelity
After having reviewed the PrimaLuna DiaLogue Premium extensively and having tested it with KT150 tubes, my aim for this mini-review is to see how it behaves with KT88 tubes. Disclaimer: my findings below need not be stereotypical for all KT88 tubes because different brands will likely have different presentations.
Normally fitted with EL34’s, this time the amp has been fitted with Shuguang KT88 tubes which I borrowed from a Line Magnetic amp that was on a visit for review.
I’ve commented before on how solid and sonorous the PrimaLuna sounds, with a capability to drive just about any loudspeaker with surprising authority, even with EL34’s and in Triode mode, which I still prefer. Even its timbre is spot-on natural and the amp always sounds convincing. However, its Achilles-heel, if you can call it that, is that it can be a little rough. What it achieves at its modest price is great but is not the most refined or most detailed amp around. As can be read in the earlier Tube Rolling part 1 review, swapping EL34’s for KT150’s does make a large difference, raising the PrimaLuna’s performance in many important aspects. However, it seems that the amp does not extract the maximum from these tubes and ultimately I feel that it works more synergetically and more sensuous with the EL34’s even if it has less power that way.
The Line Magnetic LM-88IA costs a little less than the PrimaLuna, yet it comes with KT88’s and is actually an integrated amp that can also be used as a power amp. This Chinese newcomer surprised me with its highly refined and smooth sound while being almost as powerful and sonorous as the PrimaLuna. Now, I wondered, how much of this would be due to its tube complement?
And so, I also tried the Line Magnetic’s Shuguang KT88 tubes in the PrimaLuna and although this made the amp sound significantly fuller and smoother, its bolder and rougher nature still shone through. This further proves the point that tubes in and of themselves are only partially responsible for an amplifier’s sound and in this case, the Line Magnetic LM-88IA’s more refined character is indeed more the result of its design more so than of the choice of tubes. It is my suspicion that the PrimaLuna sounds as solid and beefy as it does mainly because it employs very large transformers in its power supply and its outputs. While this clearly has many advantages, I think this is also responsible for it being less refined than some other amplifiers. The Audio Research Ref75 SE is also a good example. While rated at 75 watts, it is highly refined but sounds a lot less powerful than the PrimaLuna even with EL34’s, in spite of the ARC amp using KT150 tubes. The Ref75 SE employs small but precisely wound transformers which makes it excel in certain audiophile aspects but also leads to a less powerful bass.
Back to the PrimaLuna, I’d certainly recommend trying it with KT88’s as this provides a very nice alternative, although I still find that it sounds most well-balanced (if certainly less colorful) with its stock EL34’s.