SE KT66

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redclayrebel
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SE KT66

Post by redclayrebel »

B4D15F6A-D857-49E9-945F-0794C08E2F49.jpeg
One KT66, one 12AX7, Hammond iron, choke input filter, volume and tone, approx 15 watts. Outrageous overdrive when cranked. Not too loud though, compared to a Trinity S111 I built a few years back. The red one is the sister amp, with all Sprague caps and 2x10.
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JMPGuitars
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Re: SE KT66

Post by JMPGuitars »

That's a big tube! How do you like that speaker? I haven't tried that one, but I dig WGS stuff.
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redclayrebel
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Re: SE KT66

Post by redclayrebel »

I ordered the Invader 50 first, but just too much top end for this circuit. The ET65 seems to naturally shave off some top end sizzle. Kinda like a G12T-75 I used to have in a Marshall 1931A and B cabs.
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redclayrebel
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Re: SE KT66

Post by redclayrebel »

Yes it is a big bottle, hence the name ‘Mason Jar’, and the white cab was built by Sourmash. The red one I don’t know who made it ,I got it used and converted it to 2x10.
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That’s the red cab before I changed to 2x10 and different grill cloth with gold piping.
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JMPGuitars
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Re: SE KT66

Post by JMPGuitars »

redclayrebel wrote:
Mon 04/17/23 3:39 pm
I ordered the Invader 50 first, but just too much top end for this circuit. The ET65 seems to naturally shave off some top end sizzle. Kinda like a G12T-75 I used to have in a Marshall 1931A and B cabs.
I like the tone of the Invader 50, but I agree it can be too bright for some circuits. Thanks for the info on the ET65, that's definitely good to know. I'll have to try it out the next time I want some ceramic.
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redclayrebel
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Re: SE KT66

Post by redclayrebel »

I think next I’d like to build one of the circuits here. Looking at the 18watt EF86 lite IIb, or the one with added gain control.I’m a little concerned with finding a non microphonic EF86. Any suggestions?
Thinking it should be in a head box and not a combo.
Also transformers, especially the output.
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Re: SE KT66

Post by JMPGuitars »

redclayrebel wrote:
Tue 04/18/23 7:55 am
I think next I’d like to build one of the circuits here. Looking at the 18watt EF86 lite IIb, or the one with added gain control.I’m a little concerned with finding a non microphonic EF86. Any suggestions?
Thinking it should be in a head box and not a combo.
Also transformers, especially the output.
I think you mean the EF86 Lite 2P? That circuit is less prone to microphonics. My suggestion is to buy a few EF86s or the less expensive 6J32P Russian equivalent. You can roll them and see what sounds best.

You're less likely to have microphonic issues in a head anyway.

If you can find a genuine RFT NOS EF86, then those also tend to be less microphonic. I made an EF86 Lite (not the improved 2P) years ago, with reverb, in a combo, and didn't have any issues with that tube.

If you want the extra gain knob, that's the EF86 Xtra, go for it. The EF86 Lite 2P is identical except for the extra gain stage in the Xtra version. Hence the name. 😉

Thanks,
Josh
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yello
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Re: SE KT66

Post by yello »

JMPGuitars wrote:
Tue 04/18/23 8:46 am

I think you mean the EF86 Lite 2P? That circuit is less prone to microphonics. My suggestion is to buy a few EF86s or the less expensive 6J32P Russian equivalent. You can roll them and see what sounds best.

If you want the extra gain knob, that's the EF86 Xtra, go for it. The EF86 Lite 2P is identical except for the extra gain stage in the Xtra version. Hence the name. 😉
I built Josh's EF86 Lite 2P, and it is a fantastic amp. I don't have any problems with microphonics - mine is a head and the v1 tube socket is insulated from vibrations with rubber grommets.

I do plan to build the EF86 Xtra at some point too!
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Re: SE KT66

Post by yello »

redclayrebel wrote:
Mon 04/17/23 9:54 am
One KT66, one 12AX7, Hammond iron, choke input filter, volume and tone, approx 15 watts. Outrageous overdrive when cranked. Not too loud.
Do you have a schematic/layout of this SE KT66 build, including PT/choke/OT specs? Looks like a fun one to build!
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redclayrebel
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Re: SE KT66

Post by redclayrebel »

Yes, it’s based off the Weber 5F2H. I had to change some things, the Hammond 270EX doesn’t have a heater center tap so you have to make an artificial one with 2 100 ohm resistors. The OT is the 125ESE, the choke is the 158Q. The value of that choke bothers me a bit, I’d like more milliamps, but it’s works so far.
No standby switch, I like to use a thermistor.
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The red amp had a 5AR4 rectifier, but they’re both solid state now, red has a Yellowjacket plug in and the white uses 1N4007 diodes.
Up and running, I had to change the cathode bias resistor, each amp required a different value (?) using Rob Robinette’s online bias calculator.
https://robrobinette.com/Tube_Bias_Calculator.htm
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