Tung-Sol 6098/6AR6 Substitution

[mbeards]

Hi everyone,

I have heard of one guy using T-S 6098 tubes as a replacement in an 6550 PP ultra-linear amp who was very enthusiastic about the swap after a quick re-bias. He was clamming that the power output was close to 100 watts per pair and said they sounded like some of the best NOS 6550 without the cost and able to achieve higher power output.

Looking quickly at the curves that doesn't seem too far fetched since since the tube is capable of large current swings. Especially if the screen voltage is increased.

I am wondering if anyone has tried swapping in the 6098 tubes for hi-fi use in a 6L6 amp and especially in a 6550/KT88 amp.

-Matt

[Palustris]

The problem with these tubes as a replacement for the 6L6 (not 6550) has always been the max screen rating of 315V. They would work great as a pentode in an amp with a regulated screen supply of 300V. It is possible they would work in a 6L6 amp with ultra linear or triode connection of 400V, but is not recommended by Tung Sol.

[mbeards]

Ok, thats what I got out of the data sheets as well but the one person I heard of using them as a 6500 sub said the screens had no problem of seeing 450V because it is in ultra linear. This sounded odd to me.

[Palustris]

There's a related tube, the 6384, which is a Bendix special high reliability and high performance version. Bendix lists a max screen voltage of 375 for extreme use with reduced life expectancy. I have a bunch of these tubes but never got around to using them.

6384 data sheet

[Triodethom]

Originally Posted by Palustris

There's a related tube, the 6384, which is a Bendix special high reliability and high performance version. Bendix lists a max screen voltage of 375 for extreme use with reduced life expectancy. I have a bunch of these tubes but never got around to using them.

6384 data sheet

You are lucky give what they bring on ebay . Having heard one amp with them pentode with 300 regulated screens is a very good way to go .

[ChrisA]

Originally Posted by mbeards

Hi everyone,

I have heard of one guy using T-S 6098 tubes as a replacement in an 6550 PP ultra-linear amp who was very enthusiastic about the swap after a quick re-bias. He was clamming that the power output was close to 100 watts per pair and said they sounded like some of the best NOS 6550 without the cost and able to achieve higher power output.

Looking quickly at the curves that doesn't seem too far fetched since since the tube is capable of large current swings. Especially if the screen voltage is increased.

I am wondering if anyone has tried swapping in the 6098 tubes for hi-fi use in a 6L6 amp and especially in a 6550/KT88 amp.

-Matt

I think the results of a tube swap (even with a bias adjustment) depends a LOT of the exact output transformer you have. I doubt you get 100W from a transformer designed for a 6L6.

Running the screens over their spec's voltage in UL mode might not be so bad as much of the cycle will be well under the peak. The limit may apply to screens connected to DC. I gues it depends on the failure mode. Do ther over heat or do they arc over.

Usually that is the problem with reading about other people's tube rolling experiments. You amp has different parts and maybe different topology so the results don't transfer well.