2. amps-preamps
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Tube newbee question

After 30+ years of solid state I now have a bran new Octave V70se currently running sed winged KT88's. I noticed 1 tube glowed a much a brighter blue than the other 3. 2 nights ago (day 5) I also noticed the blue would flicker with the bass. I turned the volume from a 9 o'clock position to about 10:30 when 1 cornor of the tube seemed to get super bright - then a bright blue flash occured with the Octave going into protection mode. Also heard a thud/pop from my right speaker. Recycled power and verified that the bias was set corectly - which it was. I left it in for a couple more hours and it still works but has a much brighter blue glow to it. Octave included a spare KT88 and the next moring I replaced that 1. Well that spare tube also has a brighter blue side. Note I will not put that original back in. Today I swapped that tube position to another and it still has a brighter blue side in the different spot. Today is day 7. So for now I have to assume I had 1 bad tube. My question is seeing a KT88 or even 6550 that glows a brighter blue than the rest a problem to worry about? The last thing I noticed is that both tubes that glow blue brighter needs to have the bias turned lower. The tubes are supposed to be a match quad set.

I also have a matched quad set of EL34's and a matched quad set of 6550's on order. All are factory sed winged c's. I want to eventually pick a favorite tube which is why I got the other sets.

Last my Octave dealer forwarded my concern to Octave and we are waiting for a response. I would like to get any opinions if this is something to worry about.

THANKS
xti16
xti16 OP
1,525 posts
 
Thanks Griffithds
I'll keep them in mind. Hoping Octave will replace it. I did just buy the V70se and 2 additional quad sets of tubes.
jrinkerptdnet
430 posts
 
MOST manufacturers warranty the tubes for at LEAST 90days if not longer when an amp is purchased new from an authorized dealer. Not sure why your dealer would even have to wait for a response from Octave but ...

Jeff
xti16 OP
1,525 posts
 
Yes I am getting a replacement.
audioquest4life
763 posts
 
Xti16,

I have tube rolled Octave MRE 130's for years, driving B&W N800's. Currently, I have a set eight of SED KT88's in primary use. I also have EH KT88's and Gold Lion KT88's that I swap in and out from time to time. Originally I have TAD tubes that were good but seemed to bite the dust after a few months. You have experienced a bad tube for sure. Good thing that Octave builds in bullet proof protection circuitry to save your components.

The advantage of getting a Black Box or Super Black Box is that you will have more AC capacitance in the transformers, an increase in available AC power to drive your speakers. The difference between an amplifier using a Super Black Box; V70, V80 and MRE 130 is night and day. The bass is more powerful and the system can play louder. Overall, the musical presentation is more defined and it is easier to drive your difficult load speakers.

The dynamic and tonal stability of an amplifier is strongly dependent upon the stability and capacity of the power supply, therefore the Black Box and Super Black Box were developed as external upgrades to the OCTAVE amplifiersÂ’ power supply storage capacitors by increasing their capacitance by a factor of 4 (Black Box) or 10
(Super Black Box), respectively. This is a tremendous benefit if the speaker is difficult to drive. Loudspeaker efficiency is made less critical, while the amplifier is enabled to handle speakers with minimum impedances as low as 2 Ohms.
The power supply capacitance increase realized via use of the Black Box or Super Black Box stabilizes current delivery and reduces the impedance interaction of the load. This improves dynamic range, separation, depth, soundstage size and articulation, rendering the
musical reproduction clearer throughout the entire frequency range.
The amplifier remains unaffected by mains variations and interferences due to the noise filtering characteristics of the capacitors.

I just upgraded to the Octave Jubilee preamp. What a difference that has been compared to the Octave HP500SE. I am seriously thinking about upgrading to the Octave Jubilee monoamps.

I have been a satisfied Octave customer for years.

Where are you located?

Ciao

Audioquest4life
xti16 OP
1,525 posts
 
I live in a suburb of Chicago. My speakers are Dynaudio C1's. Funny you mention the black box. I've asked my Octave/dyn dealer to set me up with a black box demo. I read avsforum and Mick from Dynaudio recommends the black box for the C1's and super black box for the larger speakers.

I was able to audition the Jubilees with the Dynaudio Consequence UE at a private showing. All I can say is WOW.
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