Octave Tube Electronics Owners Thread - Page 4 - AVS Forum
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post #91 of 104 Old 09-28-2013, 04:34 AM
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Originally Posted by lmf22 View Post

I will probably try the little tubes in a couple of months. I want to get familiar with the new power tubes first.
Any recommendations for the three small tubes?
Depends.. If you like a warmer sound vintage Mullards (haven't tried the re-issue). More detail Telefunken - RFT - Gec. Which tubes are in your V70se now? I find the Sovtek 12ax7lps input to be very forward and quite detailed.

That being said it's all about total system synergy and your personal taste. I would also caution against using Eat KT88's and vintage Tesla's due to the higher plate voltage the Octave has (540V) for output tubes. I have been told even though those tubes are rated at 600V max they were optimally designed to run at 450V.
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post #92 of 104 Old 09-29-2013, 07:58 PM
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Originally Posted by OctaDyn_Dude View Post

Depends.. If you like a warmer sound vintage Mullards (haven't tried the re-issue). More detail Telefunken - RFT - Gec. Which tubes are in your V70se now? I find the Sovtek 12ax7lps input to be very forward and quite detailed.

That being said it's all about total system synergy and your personal taste. I would also caution against using Eat KT88's and vintage Tesla's due to the higher plate voltage the Octave has (540V) for output tubes. I have been told even though those tubes are rated at 600V max they were optimally designed to run at 450V.

I believe the the three small tubes are the stock ones that came with the V70SE (I bought it used so I cannot be sure). Two of the little tubes have a "M" logo on it but not sure what the manufacturer is. One of them is Sovtek.
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post #93 of 104 Old 09-04-2014, 12:35 PM
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Question

I have an Octave V70SE with Gold Lion KT88 tubes. One of them (in socket #4 ) broke last night; a little piece of plate fell off and the amp went into protection mode. It sucks because it's only 1 year old.

I'm ordering two more Gold Lion KT88 (one for replacement, one for spare). I'm wondering how I should place them:
1) Put one new tube in socket #4 socket; keep old tubes in sockets #1-3 ?
2) Put two new tubes in #3 and 4 (right channel)?
3) Put one new tube in left channel and one in right channel? (So it would be #1-old , #2-new , #3 -old, #4 new)?
Does it even matter?

Also, I'm upgrading the three driver tubes. I got one Gold Lion ECC83/12AX7 and two Mullard CV4024/12AT7/ECC81. This should be fun.
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post #94 of 104 Old 09-04-2014, 02:12 PM
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Personally I would just replace the one in socket 4 because the Octave is manual bias. But if it would make you feel better maybe replace both 3 & 4 and keep #3 for a spare.

The Mullard CV4024's are very warm sounding tubes which sound great with Dyn speakers.

Good Luck
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post #95 of 104 Old 09-04-2014, 04:37 PM
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Quote:
Originally Posted by OctaDyn_Dude View Post
Personally I would just replace the one in socket 4 because the Octave is manual bias. But if it would make you feel better maybe replace both 3 & 4 and keep #3 for a spare.

The Mullard CV4024's are very warm sounding tubes which sound great with Dyn speakers.

Good Luck
Thanks for quick reply! Upscale Audio shipped the tubes today, so I can pick it up from UPS' customer center tomorrow morning.
I will go with what an experience user like yourself would do; replace the one in socket 4
I've read some great reviews about the Mullard CV4024, but not specifically with Dynaudio speakers. Glad to know they will work well with my speakers (Contour S3.4).
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post #96 of 104 Old 09-05-2014, 03:56 AM
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When I had the Dyn C1 sig's I loved the Mullard CV4024 and Telefunken 5965's especially with original Tung Sol 6550 solid black plates. I also liked the RCA 5751 triple mica black plate in place of the 12ax7 (another nice warm sound). I really hated the TS KT120's (very forward and in your face but punchy). Other Octave/Dynaudio owners agreed. Well that all changed when I upgraded to the Raidho D1's. Now the KT120's sound great and the Ei KT90 type 2 sounds the best. Honestly the Ei KT90's sound great with either speaker.
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post #97 of 104 Old 09-05-2014, 11:04 AM
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Quote:
Originally Posted by OctaDyn_Dude View Post
When I had the Dyn C1 sig's I loved the Mullard CV4024 and Telefunken 5965's especially with original Tung Sol 6550 solid black plates. I also liked the RCA 5751 triple mica black plate in place of the 12ax7 (another nice warm sound). I really hated the TS KT120's (very forward and in your face but punchy). Other Octave/Dynaudio owners agreed. Well that all changed when I upgraded to the Raidho D1's. Now the KT120's sound great and the Ei KT90 type 2 sounds the best. Honestly the Ei KT90's sound great with either speaker.
I will keep those in mind next time I feel like tube rolling

Another thing. I noticed the amp takes a while to warm up. I turn it on for about 30 minutes (without any music playing) and set the bias to all green. But after another 15-30 minutes (total 1 hour without music playing), the bias indicators would be at green/red or red. Should I then readjust the bias to all green? Should I just warm up for a hour before adjusting the bias?
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post #98 of 104 Old 09-05-2014, 11:54 AM
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Originally Posted by lmf22 View Post
I will keep those in mind next time I feel like tube rolling

Another thing. I noticed the amp takes a while to warm up. I turn it on for about 30 minutes (without any music playing) and set the bias to all green. But after another 15-30 minutes (total 1 hour without music playing), the bias indicators would be at green/red or red. Should I then readjust the bias to all green? Should I just warm up for a hour before adjusting the bias?
That is quite common. Again I would adjust them for all green and if they drift up to green/red or all red I would them back down to all green. Then check them again in a couple of hrs again. I've been told from Andreas (through Dynaudio) that all green if fine and will likely make the tubes last even longer. I've had tubes take up to 3 weeks to settle down. I've also seen tubes drop after a warmup.

That said I normally play music only after 2-3 min of warmup and that seems to accelerate the changes in bias. Playing music loud also seems to accelerate the process and sometimes causes the bias to change again. I would also recommend if you change tubes a lot like I do make sure the pins in the output tube sockets are tight. Loose pins can and will make the bias jump all over the place including protection mode. Goes to say make sure power is off and cooled down because the pin that has the plate voltage is 540V and the pin with grid voltage is 310V.
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post #99 of 104 Old 09-21-2014, 08:01 PM
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Bad luck... I got a set of four Gold Lion KT88 a little more a year ago and in the past month I had two of them go out. (I have the Octave V70SE.) With the first one (tube #4 ), it was easy to spot what was wrong; a piece of metal from the bottom of the tube broke and jumped up to the top (clearly visible). But I'm not sure what's wrong with this one (tube #1 ). Right before the amp went into protection mode, there was a dark blue/purple flash. Anyone know that might cause that?

Since two of the tubes went out in a month, I'm hoping it's just bad luck with the set of four tubes that I got last year, and nothing wrong with the amp.
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post #100 of 104 Old 09-23-2014, 04:12 AM
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Quote:
Originally Posted by lmf22 View Post
Bad luck... I got a set of four Gold Lion KT88 a little more a year ago and in the past month I had two of them go out. (I have the Octave V70SE.) With the first one (tube #4 ), it was easy to spot what was wrong; a piece of metal from the bottom of the tube broke and jumped up to the top (clearly visible). But I'm not sure what's wrong with this one (tube #1 ). Right before the amp went into protection mode, there was a dark blue/purple flash. Anyone know that might cause that?

Since two of the tubes went out in a month, I'm hoping it's just bad luck with the set of four tubes that I got last year, and nothing wrong with the amp.
I had some Sed tubes (both 6550 and KT88) that had a blue glow. I was told that wasn't a problem and common for Sed tubes. Sounds like the tube arced over. My first tube failure had a blue flash before protection mode. Since the second tube failure was in a different socket I don't believe the amp is at fault. Does the bias stay steady on all tubes especially after a couple of hours? Something I found a while back is if you are checking the bias take a pen or pencil and lightly tap each tube and see if the bias jumps around. If so you may have loose pins in that socket.
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post #101 of 104 Old 09-24-2014, 09:00 AM
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Originally Posted by OctaDyn_Dude View Post
I had some Sed tubes (both 6550 and KT88) that had a blue glow. I was told that wasn't a problem and common for Sed tubes. Sounds like the tube arced over. My first tube failure had a blue flash before protection mode. Since the second tube failure was in a different socket I don't believe the amp is at fault. Does the bias stay steady on all tubes especially after a couple of hours? Something I found a while back is if you are checking the bias take a pen or pencil and lightly tap each tube and see if the bias jumps around. If so you may have loose pins in that socket.
The bias seems pretty stable. Every once awhile, after some louder than usual music, one or two tubes' bias might go up a little (green and dim red).
I tried tapping each tube while checking the bias; no changes. That's a good trick.
Thanks for the help!
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post #102 of 104 Old 09-24-2014, 09:55 AM
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Originally Posted by lmf22 View Post
The bias seems pretty stable. Every once awhile, after some louder than usual music, one or two tubes' bias might go up a little (green and dim red).
I tried tapping each tube while checking the bias; no changes. That's a good trick.
Thanks for the help!
Very normal. At least it isn't a socket problem. Honestly it sounds to me you had a couple of bad tubes.
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post #103 of 104 Old 09-25-2014, 09:59 AM
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Very normal. At least it isn't a socket problem. Honestly it sounds to me you had a couple of bad tubes.
I hope it is just bad tubes. But that means the other two tubes have a good chance of going bad soon (I ordered them at the same time last September, so they're probably from the same batch. I just went ahead and ordered two more as spares, just in case.

One last thing. If I listened at low volume and adjust bias to all green, then listened at higher volume and found that it went up (green and red), should I turn the bias down to all green? I assume the answer is yes, but just to make sure

Last edited by lmf22; 09-25-2014 at 10:08 AM. Reason: Added one more question.
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post #104 of 104 Old 09-25-2014, 02:11 PM
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Originally Posted by lmf22 View Post
I hope it is just bad tubes. But that means the other two tubes have a good chance of going bad soon (I ordered them at the same time last September, so they're probably from the same batch. I just went ahead and ordered two more as spares, just in case.

One last thing. If I listened at low volume and adjust bias to all green, then listened at higher volume and found that it went up (green and red), should I turn the bias down to all green? I assume the answer is yes, but just to make sure
Yes that's how I do it with most tubes. The only tubes I do push to green/red at louder volumes is the Ei KT90 and TS KT120's. All others I keep at all green per Andreas suggestion for longer tube life.
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