6L6 vs KT66
Moderators: pompeiisneaks, Colossal
Re: 6L6 vs KT66
The higher primary impedance of the OT make a big difference.
Simply put: The 3400 ohms primary (50w) yields a more 70's tone compared to the higher 6600 ohms OTs (also 50w) that were used in 60's marshalls.
I have not tried the KT66 though, but I'm getting curious! I have only tested this with ef2 EL34 tubes and the difference was very clear.
Jelle
Simply put: The 3400 ohms primary (50w) yields a more 70's tone compared to the higher 6600 ohms OTs (also 50w) that were used in 60's marshalls.
I have not tried the KT66 though, but I'm getting curious! I have only tested this with ef2 EL34 tubes and the difference was very clear.
Jelle
Re: 6L6 vs KT66
Has anyone here tried the new JJ KT66s yet?
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- David Root
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Re: 6L6 vs KT66
No, I haven't, not yet, but I surely will, assuming they are in fact REAL KT66s and not 6L6GCs in a big bottle. I'll consult my tube supplier, Lord Valve. He's always up-to-the-minute on new tubes.
The best JTM45 OT, the Radiospares De Luxe, had both 8k pentode and 6k6 UL secondaries (also 9K pentode for EL84s). Most folks seem to use the 8k pentode for the JTM 45, but 6k6 is the logical step between 8k and 3k4.
Is your EICO OT a standard pentode winding or a UL winding? Sounds like a good bet to me either way, especially as it's "large"!
The best JTM45 OT, the Radiospares De Luxe, had both 8k pentode and 6k6 UL secondaries (also 9K pentode for EL84s). Most folks seem to use the 8k pentode for the JTM 45, but 6k6 is the logical step between 8k and 3k4.
Is your EICO OT a standard pentode winding or a UL winding? Sounds like a good bet to me either way, especially as it's "large"!
Re: 6L6 vs KT66
I've been on vacation last week so I didn't see your post. The Eico has UL taps but I didn't check the voltage ratio on them when I calc the Primary at 6.6K. I'll check the turns ratio on them but It would be a lower Impedance than the plates. The Eico is a potted tranny and quite large. I orignally thought about a Wreck tranny with EL 34's but will pickup some KT66's from Lord Valve next time I'm at his shop.
- leadfootdriver
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Re: 6L6 vs KT66
Would I use the same Screen and Input Grid Resistors from the 6L6 when switching to KT66?
The amp I have uses 470R for the Screens and 2.2K at G1..
The amp I have uses 470R for the Screens and 2.2K at G1..
Re: 6L6 vs KT66
hardly, since a real kt66 draws more screen current than a 6L6. What is the voltages and the Z?leadfootdriver wrote: ↑Sat Jan 06, 2024 2:41 am Would I use the same Screen and Input Grid Resistors from the 6L6 when switching to KT66?
The amp I have uses 470R for the Screens and 2.2K at G1..
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Re: 6L6 vs KT66
Dunno.. I don't have it all together yet. But I'm flip flopping on Power Tubes.
I'll start another Topic..
I'll start another Topic..
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Re: 6L6 vs KT66
Do you know what the KT stands for?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6L6 vs KT66
Mentioned up the thread, KT stands for "Kinkless Tetrode." Normal tetrodes have a kink in their characteristic curves. Beam-forming plates in KTs (and 6L6) largely remove this kink and provide a smoother pentode-like response.
Re: 6L6 vs KT66
I never even seen a real MOV KT66, nevermind tested an amp with them to see how they perform. But comparing the 250V pentode conditions for 6L6 and KT66 indicates the g2 currents seem pretty similar.Roe wrote: ↑Sat Jan 06, 2024 10:38 amhardly, since a real kt66 draws more screen current than a 6L6 …leadfootdriver wrote: ↑Sat Jan 06, 2024 2:41 am Would I use the same Screen and Input Grid Resistors from the 6L6 when switching to KT66?
The amp I have uses 470R for the Screens and 2.2K at G1..
Whereas suppressor grid type pentodes such as EL34 will have somewhat higher g2 current.
https://frank.pocnet.net/sheets/126/k/KT66.pdf
https://frank.pocnet.net/sheets/127/6/6L6GB.pdf
https://frank.pocnet.net/sheets/010/e/EL34.pdf
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Re: 6L6 vs KT66
some of the newer kt66s perform more like 6L6s, particularly the tung-sol and to a somewhat lesser extent the chinese shuguang ones. Basically, these draw less screen current than the old UK kt66s (the gold lion RI draws more than the chinese ones typically)pdf64 wrote: ↑Wed Jan 10, 2024 12:09 amI never even seen a real MOV KT66, nevermind tested an amp with them to see how they perform. But comparing the 250V pentode conditions for 6L6 and KT66 indicates the g2 currents seem pretty similar.Roe wrote: ↑Sat Jan 06, 2024 10:38 amhardly, since a real kt66 draws more screen current than a 6L6 …leadfootdriver wrote: ↑Sat Jan 06, 2024 2:41 am Would I use the same Screen and Input Grid Resistors from the 6L6 when switching to KT66?
The amp I have uses 470R for the Screens and 2.2K at G1..
Whereas suppressor grid type pentodes such as EL34 will have somewhat higher g2 current.
https://frank.pocnet.net/sheets/126/k/KT66.pdf
https://frank.pocnet.net/sheets/127/6/6L6GB.pdf
https://frank.pocnet.net/sheets/010/e/EL34.pdf
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