It’s official, KT66’s will be standard!!

RedPlated

RedPlated

Well-known member
I absolutely love these tubes. The next batch of amps will all be KT66. Just ordered a bunch direct from ARS Electronics.

Pretty pricey tubes but the tone is worth it!

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@RedPlated had poked at me a couple of times to give KT66 a try in the Hellion and I've finally made the switch from EL34 a few weeks ago. He had a some extra sets on hand, so I bought them directly from him.

I should have done this sooner. It's not a massive difference from EL34, but enough to bring the Hellion to the next level of tone. The character of the Hellion still remains the same, but the sound has more girth. Compared to EL34 you still have the upper mid grind character, just a tad smoother. The big thing I'm picking up is lower-mid dynamics that to me make it sound beefier and more full. There's also slightly accentuated highs that balance out the additional lower-mids without making anything sound spikey.

The best way to describe it is how Jeremy has already said, it just sounds more massive. If you're still running EL34 or 6L6 and think it sounds good, you really need to switch over to KT66. I don't think you'll be disappointed.

I want to mention a quick note on biasing for anyone doing it themselves since I didn't see it posted anywhere else...
Keep in mind this for the ARS tubes Jeremy is currently putting in the Hellion. I don't know if it holds true for other brand KT66.
Jeremy, Please correct me if I got any of this wrong.
Jeremy had told me he sets the bias at 43 mA with the KT66. When measuring the DCV I thought this would put the dissipation near max. So I biased my amp at 36 mA based on a measured 487 DCV and 25 watts, which would put that at a calculated 70% dissipation. Talking more with Jeremy about this, he had conversations with his tube guy that said the KT66 he's using are rugged, will handle higher currents, and are more like 30 watts. So calculating at 30 watts instead of 25 watts, 43 mA would be 70% dissipation. Jeremy has told me that neither he nor any of his customers have had any issues with the Hellion being biased like this. I'll eventually get around to upping the bias on mine as well.
 
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I have a Marshall Vintage Modern 2466 that uses KT66s. I find it a bit looser in the bottom end than my EL34 amps. I always attributed that to the KT66s. Am I wrong about that?

I really like the amp but I think it could use a bit of tweaking.
 
homespun said:
I have a Marshall Vintage Modern 2466 that uses KT66s. I find it a bit looser in the bottom end than my EL34 amps. I always attributed that to the KT66s. Am I wrong about that?

I really like the amp but I think it could use a bit of tweaking.
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I tried the GL KT66s in a SLO one time, it was much looser as well. No go for me.
 
MadAsAHatter said:
@RedPlated had poked at me a couple of times to give KT66 a try in the Hellion and I've finally made the switch from EL34 a few weeks ago. He had a some extra sets on hand, so I bought them directly from him.

I should have done this sooner. It's not a massive difference from EL34, but enough to bring the Hellion to the next level of tone. The character of the Hellion still remains the same, but the sound has more girth. Compared to EL34 you still have the upper mid grind character, just a tad smoother. The big thing I'm picking up is lower-mid dynamics that to me make it sound beefier and more full. There's also slightly accentuated highs that balance out the additional lower-mids without making anything sound spikey.

The best way to describe it is how Jeremy has already said, it just sounds more massive. If you're still running EL34 or 6L6 and think it sounds good, you really need to switch over to KT66. I don't think you'll be disappointed.

I want to mention a quick note on biasing for anyone doing it themselves since I didn't see it posted anywhere else...
Keep in mind this for the ARS tubes Jeremy is currently putting in the Hellion. I don't know if it holds true for other brand KT66.
Jeremy, Please correct me if I got any of this wrong.
Jeremy had told me he sets the bias at 43 mA with the KT66. When measuring the DCV I thought this would put the dissipation near max. So I biased my amp at 36 mA based on a measured 487 DCV and 25 watts, which would put that at a calculated 70% dissipation. Talking more with Jeremy about this, he had conversations with his tube guy that said the KT66 he's using are rugged, will handle higher currents, and are more like 30 watts. So calculating at 30 watts instead of 25 watts, 43 mA would be 70% dissipation. Jeremy has told me that neither he nor any of his customers have had any issues with the Hellion being biased like this. I'll eventually get around to upping the bias on mine as well.
Click to expand...
Yeah I run them at 43ma. They sound the best there for sure. There’s mixed opinions on whether a KT66 is 25 or 30 watts. But ARS assured me they will handle the extra current no problem. I have a local buddy who cranks his Hellion super loud continuously and no issues so far.
CrazyNutz said:
I tried the GL KT66s in a SLO one time, it was much looser as well. No go for me.
Click to expand...
I thought they would be, but there is no loss of tightness on the bottom end in this amp.

homespun said:
Hey my friend, is the only difference the bias setting? Is this the same for any amplifier?
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Depends on the amp. But with mine it’s just the bias setting. Same transformer. Technically, the impedance of the OT and the KT66’s are a slight mismatch. But it sounds so good I don’t want to change it. Sometimes mix matched parts can create a better sound.
 
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