Hi
I am driving 2A3 with D3a (as triode) RC coupled and the result is good
I bought a pair of hammond interstage transformers 126B to try difference than RC coupling
I try them with EC8010 triode and have bad sound! Something like losing frequensies...
Did I make something wrong?
Should I try them with different tube?
Hammond Mfg. - Audio - Tube Driver Transformer - (124 - 126 Series)
I am driving 2A3 with D3a (as triode) RC coupled and the result is good
I bought a pair of hammond interstage transformers 126B to try difference than RC coupling
I try them with EC8010 triode and have bad sound! Something like losing frequensies...
Did I make something wrong?
Should I try them with different tube?
Hammond Mfg. - Audio - Tube Driver Transformer - (124 - 126 Series)
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Looks like but:Inductance is a bit low so you might have earlier lf rolloff than before.
Inductance of Hammond 126B is 44H
Tango NC-14 has 50H
Does not look to have low inductance compared to NC-14
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OK - I have some experience here:
1. Swap the secondary leads. The treble should come back again. It needs to be wired up right.
2. Try it out as a plate choke, with teflon FT-3 coupling caps. I use 0.1uF followed by 100K grid leak.
I prefer it as a plate choke where it's a great choice. You shouldn't have any treble issues there.
1. Swap the secondary leads. The treble should come back again. It needs to be wired up right.
2. Try it out as a plate choke, with teflon FT-3 coupling caps. I use 0.1uF followed by 100K grid leak.
I prefer it as a plate choke where it's a great choice. You shouldn't have any treble issues there.
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OK - I have some experience here:
1. Swap the secondary leads. The treble should come back again. It needs to be wired up right.
2. Try it out as a plate choke, with teflon FT-3 coupling caps. I use 0.1uF followed by 100K grid leak.
I prefer it as a plate choke where it's a great choice. You shouldn't have any treble issues there.
Thanks Andy
I'll try tomorrow and tell you the result
Thanks Andy
I'll try tomorrow and tell you the result
One or the other should work. Plate choke should definitely solve the problem and the teflon FT-3 caps are by a long way the best I've tried. The 4P1L in filament bias is perfect with the 126B. Run it at around 25mA. Has a gain of 9 or 10. That's what I use. Long thread for "4P1L Line Stage". Should be in filament bias with Rod Coleman regs. I attach a schematic to give you the idea. As you can see I use PSE 4P1L instead of 2a3 so that with a gain of 9 or 10 I only need 2 stages. Can't do that with the 2a3. Sounds just as good or better to my ears.
Attachments
I do not have FT-3 caps. I'll try a MKP or OIL , and will order some FT-3.
I hear too much discussion for 4P1L maybe I should buy some and try.
I use AC for filament supply but I don't have any noise..
Does rod coleman regulator improve better sound or is only for filament noise?
I hear too much discussion for 4P1L maybe I should buy some and try.
I use AC for filament supply but I don't have any noise..
Does rod coleman regulator improve better sound or is only for filament noise?
The whole idea is to use DHTs. That's where the Rod Coleman regs come in. But the added bonus of filament bias is that the cathode resistor is small - typically 30 ohms or less. So no need for cathode bypass caps. That's one source of degradation out of the way. You do need a very clean filament supply since it also goes through the cathode resistor, so it's in the signal path. But Rod's regs with a good DC supply - preferably with a choke in it - gives a very clean supply. This arrangement was proposed by Thomas Mayer (vinylsavor) and has become popular in the last few years with 26, 01A and 4P1L tubes for which it's a perfect solution. Ale Moglia writes extensively on all this on his bartola valves website. Thomas has a series of very interesting blogs on his site too.
Today I swap the secondary leads and the sound become normal
I also use the primary only as plate choke and capacitor coupling and I think Is better
I'll buy also some teflon capacitors to try
Thanks a lot Andy!
Does any have experience with EC8010 operation values?
I think datasheet isn't correct.. Ra=2.4K?? Rk=47 ohm??
I also use the primary only as plate choke and capacitor coupling and I think Is better
I'll buy also some teflon capacitors to try
Thanks a lot Andy!
Does any have experience with EC8010 operation values?
I think datasheet isn't correct.. Ra=2.4K?? Rk=47 ohm??
Today I swap the secondary leads and the sound become normal.
I also use the primary only as plate choke and capacitor coupling and I think Is better. I'll buy also some teflon capacitors to try. Thanks a lot Andy!
You're welcome! I went through this exact situation myself, so that's how I learned.
The Russian FT-3 are a tiny bit better than the K72 teflons. There is also a FT-2 rated for 200v which is good.
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