Totally Tubular: The Tube Thread

Picking up these GE 6550 tubes to see how they sound in place of the KT120 in the Rogue.
The guy ran them in his Conrad Johnson amp and sold the amp sans tubes.
He was not entirely sure exact vintage. Thought was late 60’s early 70’s as these came out of an early 70’s Ampeg SVT amplifier.. the lettering is mostly worn off but the two that still have numbers appear are KY 88-5 on one and KY 18-5.
His test data:
Tested my TV 7/U tube tester
46,46,48,46 where 44 is good.




For me there is nothing wrong with the KT120 but since I am powering the LF woofers with the Denon amp, I thought I could maybe squeeze some more tubey magic out of the mids and highs. If it's not a more favorable sound, I can probably get my $200 back selling these.

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I bought these late '60s GE 6550A tubes and finally got them in today. Man they are sounding pretty good as I play the mono Let It Bleed.

I put the tubes in around 4 hours ago, biased them at 35 mA, and left the amp on for a good 4 hours.

The mids are bringing a bit more sweetness than before. Also cranked the mid attenuator to max on the JBLs after watching a video review from Erin last night. He said it takes a little bottom end out but smooths a drop in the mids in his test. @Mather you might try this on your JBL and see what you think.

Tube shot 🥃


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I bought these late '60s GE 6550A tubes and finally got them in today. Man they are sounding pretty good as I play the mono Let It Bleed.

I put the tubes in around 4 hours ago, biased them at 35 mA, and left the amp on for a good 4 hours.

The mids are bringing a bit more sweetness than before. Also cranked the mid attenuator to max on the JBLs after watching a video review from Erin last night. He said it takes a little bottom end out but smooths a drop in the mids in his test. @Mather you might try this on your JBL and see what you think.

Tube shot 🥃


View attachment 219747
Tubes will do my head in, but damned if I don't LOVE the look of them. And I bet they sound great with the L100s. What's the wattage on that amp?
 
Tubes are like having a cool car. No logic just chasing the fun and it is addictive.


The Rogue is 60w 4 ohms triode plus the Denon is pushing everything below 450 Hz with 160w 4 ohms.
Very nice, the mids is interesting because there is definitely a drop but I already adjusted it with my room correction so I don't think it's necessary in my case but I might try it just for funzies...
 
Very nice, the mids is interesting because there is definitely a drop but I already adjusted it with my room correction so I don't think it's necessary in my case but I might try it just for funzies...
It definitely makes everything more linear here. Kind of need to recalibrate my ears after. Mainly with losing some fat bass.
 
Wilsenton R8 Update

I just added the Horizon 6SL7 to my R8 and I have to say I’m impressed. I’ve had my R8 for about 3 years and rolled more tubes than I care to admit.

Current tube complement are the Psvane 4 x KT88-T MKII, 2 x CV181-T MKII, 1 x NOS Sylvania 6SN7 and the Horizon 6SL7s.

Prior to the Horizon 6SL7 I had Tung-Sols and rebased NOS Sylvania 6SL7s. These tubes are good, very dynamic compared to the stock tubes, but ultimately a little to hot in the treble for my liking so I always defaulted back to the stock 6SL7 for a less fatiguing listen. After reading the positive reviews of the Horizon tubes I decided to give them a go before selling the R8 and moving on.

The Horizon tubes are delivering a smooth and non-fatiguing top end with good dynamics and holographic soundstage. I think I’m good for a while and will not be selling the R8 anytime soon. When the time come to upgrade other tubes I'm definitely going to give the Horizon line a shot.
 
Wilsenton R8 Update

I just added the Horizon 6SL7 to my R8 and I have to say I’m impressed. I’ve had my R8 for about 3 years and rolled more tubes than I care to admit.

Current tube complement are the Psvane 4 x KT88-T MKII, 2 x CV181-T MKII, 1 x NOS Sylvania 6SN7 and the Horizon 6SL7s.

Prior to the Horizon 6SL7 I had Tung-Sols and rebased NOS Sylvania 6SL7s. These tubes are good, very dynamic compared to the stock tubes, but ultimately a little to hot in the treble for my liking so I always defaulted back to the stock 6SL7 for a less fatiguing listen. After reading the positive reviews of the Horizon tubes I decided to give them a go before selling the R8 and moving on.

The Horizon tubes are delivering a smooth and non-fatiguing top end with good dynamics and holographic soundstage. I think I’m good for a while and will not be selling the R8 anytime soon. When the time come to upgrade other tubes I'm definitely going to give the Horizon line a shot.
Tube shots are needed for this type of post.
 
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