Power Amp Tube change, or not?

[Mordante]

I have Octave MRE130 mono amps. See:

OCTAVE Audio

This amp can use EL34, 6550, KT88, KT120 & KT150 tubes. Using KT120 or KT150 tubes will change the sound but it will not result in more power. Right now I'm using KT120 tubes.

I have been thinking about changing the KT120 for KT88 (PSVANE T series? or Linlai™ Global KT88-D) or KT150 tubes. Or will all of this be a waste of money and an exercise in futility and is my money better spend elsewhere.

I have these amps for about 5 to 6 years now. So I'm getting an itch to play with the power tubes. The other tubes have been changed.

 

[Cellcbern]

I have Octave MRE130 mono amps. See:

OCTAVE Audio

This amp can use EL34, 6550, KT88, KT120 & KT150 tubes. Using KT120 or KT150 tubes will change the sound but it will not result in more power. Right now I'm using KT120 tubes.

I have been thinking about changing the KT120 for KT88 (PSVANE T series? or Linlai™ Global KT88-D) or KT150 tubes. Or will all of this be a waste of money and an exercise in futility and is my money better spend elsewhere.

I have these amps for about 5 to 6 years now. So I'm getting an itch to play with the power tubes. The other tubes have been changed.

If you want to try KT88's the two best sounding I've ever heard were the EAT and the blue Sophia Electric. Unfortunately both are hard to find, the former having been discontinued and the latter currently sold out.

 

[mulveling]

My experience with rolling power tubes (VAC 200iq, Rogue Apollo Dark) is it will absolutely change the sound, sometimes more than you think. In fact I often find more impact here than with small tubes.

Whether that sound is good comes down to how the amp is configured, how it's been "voiced", and your system / ears. Unfortunately you just have to try and see. In bigger amps (12x tubes in Apollos, 16x tubes in VAC 300iQ) this gets VERY tedious and expensive! With only 4 tubes, I say go nuts

Some of my findings:
* KT120 sounds like it has a little rough / aggressive spot (upper mids / lower treble) on the Rogue Apollo amps but doesn't display this problem in the VAC (beautiful here). More powerful bass than KT88.
* KT150 in VAC (didn't try in Apollos) has very impressive bass power but it was "too much" and threw things out of balance. It overwhelmed the rest of the music and I couldn't evaluate them further. Borderline awful, imo.
* 7581A were awful in Apollos. I was looking for a sweet classic tube sound (like these same tubes were in a Heathkit W5, or EL34 in an Eico HF-87) and definitely didn't get it. I got dry, anemic sound. Totally defeated the point of these high-power amps.
* KT88 Gold Lion (reissue) were fantastic in both amps. A well tempered, refined tube with a touch of sweetness. Best midrange!
* KT88 EH sound is pretty close to Gold Lion but a bit more brash and "rock and roll" - but also a bit less refined and not as golden in the midrange.
* KT88 Mullard (reissue) seem very similar to GL, though I haven't directly compared them yet. These KT88 (GL, EH, Mullard) are basically 3 slight variations of the same tube from the same factory, so of course the sonic variation here isn't as great as with the other types.

In the end, though I'm a tube rolling junkie, I think it's better for an amp maker to optimize their amp for a specific type rather than accommodate a broad palette. The output transformer design factors heavily in here. I listen loud and generally prefer amps with multiple push-pull pairs per side (the more the better), but that really puts a damper on tube rolling! KT88 and KT120 are *reasonably* close enough that I feel this swap is often a good one to try (if cleared with amp maker).

 

[Mordante]

If you want to try KT88's the two best sounding I've ever heard were the EAT and the blue Sophia Electric. Unfortunately both are hard to find, the former having been discontinued and the latter currently sold out.

These tubes are very expensive. The EAT KT88 are close to 5k for 8 tubes. The Sopias are are even more expensive.

 

[Mordante]

My experience with rolling power tubes (VAC 200iq, Rogue Apollo Dark) is it will absolutely change the sound, sometimes more than you think. In fact I often find more impact here than with small tubes.

Whether that sound is good comes down to how the amp is configured, how it's been "voiced", and your system / ears. Unfortunately you just have to try and see. In bigger amps (12x tubes in Apollos, 16x tubes in VAC 300iQ) this gets VERY tedious and expensive! With only 4 tubes, I say go nuts

Some of my findings:
* KT120 sounds like it has a little rough / aggressive spot (upper mids / lower treble) on the Rogue Apollo amps but doesn't display this problem in the VAC (beautiful here). More powerful bass than KT88.
* KT150 in VAC (didn't try in Apollos) has very impressive bass power but it was "too much" and threw things out of balance. It overwhelmed the rest of the music and I couldn't evaluate them further. Borderline awful, imo.
* 7581A were awful in Apollos. I was looking for a sweet classic tube sound (like these same tubes were in a Heathkit W5, or EL34 in an Eico HF-87) and definitely didn't get it. I got dry, anemic sound. Totally defeated the point of these high-power amps.
* KT88 Gold Lion (reissue) were fantastic in both amps. A well tempered, refined tube with a touch of sweetness. Best midrange!
* KT88 EH sound is pretty close to Gold Lion but a bit more brash and "rock and roll" - but also a bit less refined and not as golden in the midrange.
* KT88 Mullard (reissue) seem very similar to GL, though I haven't directly compared them yet. These KT88 (GL, EH, Mullard) are basically 3 slight variations of the same tube from the same factory, so of course the sonic variation here isn't as great as with the other types.

In the end, though I'm a tube rolling junkie, I think it's better for an amp maker to optimize their amp for a specific type rather than accommodate a broad palette. The output transformer design factors heavily in here. I listen loud and generally prefer amps with multiple push-pull pairs per side (the more the better), but that really puts a damper on tube rolling! KT88 and KT120 are *reasonably* close enough that I feel this swap is often a good one to try (if cleared with amp maker).

My mono power amps have 4 power tubes each. Meaning I would need to change 8 tubes. Rolling 8 tubes will be close to 1000 euro. So I want to make sure the money isn't wasted. Thank you for the info I will think about it some more.