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bella extreme 3205 tubes

It is time to do a tube replacement/upgrade on my Int. Bella Extreme 3205.
It is an upgraded Jolida 502A that was upgraded by Response Audio in 2006/07.
At the present time I am running4-EH EL34 in the power output, 2-12ax7 Sovtek for the input and 2-12at7 Sovtek as the drivers.
I have about 1000 hours on these tubes and can hear a distinct degrade in the sound quality. I do bias the power tubes about every 100 hours or so.
I can run EL34,6550,and KT88 as power outputs. With the 6550/kt88 it will give me 10 more watts but it is not a necessity to go from 50WPC to 60WPC.
The inputs are what I am more interested in.
I am pushing a pair of Jupiter Audio Europa speakers and a Audio Note CDT transport with a MacCormack DAC-1 with deluxe upgrades.
So what tube would be recommended for this set up? I would like a little more
of an open mid range and the highs a bit brighter. The bass is good and I do have a small sub if I need more bottom end.
Specs can be found here.
http://www.enjoythemusic.com/magazine/equipment/0307/bella_extreme_3205.htm
Thanks Brian
skiezo
mechans
3,048 posts
 
Current production Gold Lion KT-88s suit my taste.
newbee
4,767 posts
 
"The inputs are what I'm most interested in"

Are the Sovtek 12AX7's the AX or the LPS version? Generically speaking the LPS version isn't far off from the tone you are looking for, i.e. open mid range - brighter highs, but how it combines with the EH power tubes, I don't know.

Another recent production tube for open mid-range and brightenened highs is the EI12AX7E (grey plate) if you can find them. A candidate which is easy to find is the Tung-Sol 12AX7. The Tung Sol has a bit more bass than the others.

Reconsider the power tubes you are using. I've found what you are looking for in SED KT88's or the more linear SED 6550. But there are a lot of options! Gold Lions are highly though of. I like the Tung Sol 6550's which are similar to the SED 6550's but with more bass/warmth.

Now for an unconventional recommendation. Based on my present use of them, SOVTEK KT88's. Excellent mid range and highs. Clean, clear, linear but not hyped up to impress. But a tad short on deepest bass but otherwise excellent. Not expensive. Rugged. Unless your amp is already short of bass and you need to plump it out or you are a loud bass person, these tubes can really do the job.

A caveat however, you may still want to change the small tubes to dial in the exact tone you want once you have decided on power tubes.
elevick
2,636 posts
 
If you have 1000 hours on the amp, the degradation of sound is only due to the output tubes. 12 series tubes easily last 5000 hours and can go up to 10,000 hours. Output tubes will show wear at 1000 hours.
My advice, replace the outputs only and see how it sounds. Before replacing the 12 series tubes, get them tested. You may want to consider NOS tubes for these but tube rolling is the only way to find out.
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