2. amps-preamps
  3. 182498-179366

KT120 replacement options in a Cronus Magnum II

I have a "new to me" Cronus Magnum II" that came with a shot KT120. Thankfully the am still plays with half the power on the one channel. I'm having no luck finding this tube. Being made in Russia and in high demand I expect the situation to stay lean for some time. Rouge reported that the KT88’s, KT90’s, and KT77's are all compatible. I'm new to the tube amp space and I was hoping to read for a few months before going tube shopping, but I have a situation. 

Has anyone "downgraded" the Magnum II to one of these other tubes?  I'm guessing I should buy a pair so both channels have the same output. Is that right?

What are your thoughts for the best way forward? I spent most of my budget so a pair of KT150's is really not an option. 

markcasazza
markcasazza OP
33 posts
 

I forgot to ask this clarifying question:

Yes, I was thinking of 2 KT88s. The thought was can I run a KT120 and KT88 on each channel. It sounds like that answer is "No!".  I'm a newbie and not finding good content to figure this out for myself. 

Thank you for the replies!!!

avanti1960
1,602 posts
 

do your best to find a KT120.  as long as they bias correctly you should not need to have them tested.  

KT150s will not work on the CMII.  

I had the CMII and tried KT88s.  It was an instant downgrade- weak and dull sound.  the KT120s are the real deal. 

 

decooney
2,358 posts
 

+1 @avanti1960

@markcasazza Best to follow this reply, from a known member with first hand experience on both sets of 88/120 tubes in that specific CMII amp and version you have. FYI tubes can perform and sound differently in different tube amp circuit designs and across different designer-builders. Glad to see this reply too, I run KT120s in my current mono amps myself. While my current quad of 120s and 150s are okay, and I have a spare quad of KT120s.  Checking this morning - my own tube source provider reports they may not see new quad sets of these larger KTs again until late April/May ’23. So, good news you found a KT120 or two. Worth trying first, yes.

markcasazza OP
33 posts
 

Indeed, I had the resort to eBay and there is only 1 seller shipping from China. I just ordered 2 so I have a spare. I suspect the war is causing import issues. No sign that will be over any time soon. Now I wait 3 weeks.

Avanti1960, did you roll any of the pre-amp tubes? That was my plan come next winter. I saw 1 thread indicating some success. I'll bookmark them for when my wallet recovers.

decooney
2,358 posts
 

@markcasazza yep, clearly a New Sensor TungSol tube and supplier shortage again for sad reasons of war, yes, likely. Recently I checked my former sources and a few others. Some TS tube suppliers I know of are reporting the next round of TS output tube supplies might come back in stock in April/May. But, I would not count on it.

Also just for grins I’m checking with a former overseas source provider of the prior available KT120s that use to be with label by PSVANE as KT120s, saw those a few years ago but never tried them myself. Some other non-TS options would be nice.

As a backup I recently acquired up an older familiar SS amp to rotate in once in a while any time I want to give the KT120s and KT150s a rest. If that does not go well, will plan on obtaining an EL34 amp or something. Other options nice to have.

More to discover