Hello,
I would like to make a VT-25 single-ended to drive a TAD-2001 Horn above 600 Hertz. using a Tamura Permalloy 7 kohm output and a tango 180H 12 ma or 45H 24 ma anode choke for the input Tube. Like to use tubes like e80cc, 6sn7 prefarably no tubes with prices like the VT-25. Not much gain required. I am planning to give each tube a seperate power supply with a choke- input and maybe an Allen Wright shunt-stabilisation because so far this has worked perfectly for the things constructed so far. Maybe there are some links i can consult. Thanks a lot, Ed
I would like to make a VT-25 single-ended to drive a TAD-2001 Horn above 600 Hertz. using a Tamura Permalloy 7 kohm output and a tango 180H 12 ma or 45H 24 ma anode choke for the input Tube. Like to use tubes like e80cc, 6sn7 prefarably no tubes with prices like the VT-25. Not much gain required. I am planning to give each tube a seperate power supply with a choke- input and maybe an Allen Wright shunt-stabilisation because so far this has worked perfectly for the things constructed so far. Maybe there are some links i can consult. Thanks a lot, Ed
Eduard,
I'm not quite sure what you're asking. Is it for advice about deiver stages?
Looking at the VT25 datasheet, you're going to need to swing about 60 - 80 Vpp to get full output depending on where you decide to bias it. So a choke loaded ECC99 would be my first choice, B+ = 200V, Vg = -6V, Ia = 20mA, Rk ~300R. It'll have <i>no</i> problem driving the grid on the VT25. I'd also use an interstage transformer, or a grid choke, and probably a CCS for the driver anode load.
This should give you about 1.5V sensitivity for full power. Without knowing what the rest of your system's amps and gain structure are, I'm only guessing whether that will be enough. Should be as a TAD2001 will be over 110dB/W/m, so I doubt your amp will ever get near full power.
Other options for driver tubes would be 6SN7, 6H30, 7044, 6S4, trioded SV83/ EL84 / C3m, and so on. Lots of possibilities depending on how you load and bias them, and how much gain you want.
Cheers
Brett
I'm not quite sure what you're asking. Is it for advice about deiver stages?
Looking at the VT25 datasheet, you're going to need to swing about 60 - 80 Vpp to get full output depending on where you decide to bias it. So a choke loaded ECC99 would be my first choice, B+ = 200V, Vg = -6V, Ia = 20mA, Rk ~300R. It'll have <i>no</i> problem driving the grid on the VT25. I'd also use an interstage transformer, or a grid choke, and probably a CCS for the driver anode load.
This should give you about 1.5V sensitivity for full power. Without knowing what the rest of your system's amps and gain structure are, I'm only guessing whether that will be enough. Should be as a TAD2001 will be over 110dB/W/m, so I doubt your amp will ever get near full power.
Other options for driver tubes would be 6SN7, 6H30, 7044, 6S4, trioded SV83/ EL84 / C3m, and so on. Lots of possibilities depending on how you load and bias them, and how much gain you want.
Cheers
Brett
Hello Brett, Now i am using a ef86 and el84 with a gain about 34 Db if i am right. It is a line amplifier with an outputtransformer, i think it will give about 3 watt. But i have a lot of gain in front of it so the linear pot at the input is about 25 % open with a 104 DB system . in the future i will built a 12 DB filter at the in put of this amp and use the VT-25 for the TAD-2001 which is 109 DB. So it will only be an advantage if it will have less gain then the other one. I think a tube like ecc83 will give too much gain. Ecc82, e80cc willbe i think more then enough to make a complete poweramp. The anode choke can be connected in parallel because if this amp will begin to work at 1oo Hertz it will be sufficient. The choices with a the POWER tube are not so big. It will be not so difficult to change the H.T with the input, which will also be the driverstage this will be more difficult. I like to build something with an anodechoke, a few resistors, one or two capacitors and no active devices besides the input tube. Thanks again, Ed
Eduard,
Brett's hint ot use the ECC99 makes perfect sense to me, moreover as you do not want to have too much gain.
but if you insist on using the E80CC, well, a wonderfully relaxed sounding tube, but R_p is maybe a bit highish to drive the 10Y/VT-25 grid. You will need a big anode choke for it, R_p is 7k.
The ECC99 is dirt-cheap, the E80CC about 40 Euro a piece, not a bargain.
Brett's hint ot use the ECC99 makes perfect sense to me, moreover as you do not want to have too much gain.
but if you insist on using the E80CC, well, a wonderfully relaxed sounding tube, but R_p is maybe a bit highish to drive the 10Y/VT-25 grid. You will need a big anode choke for it, R_p is 7k.
The ECC99 is dirt-cheap, the E80CC about 40 Euro a piece, not a bargain.
TUBE CHOICE
Guys,
For NOS,it is a bargain and my choice by a long way.
One of the best medium mu twin triodes ever made.
THE professional choice.
Ok,I just upped the price by posting this.
Dice45 is right the ECC99 is a very good alternative and still in production.
ECC83: you don't need that kind of gain really?It is not linear anyway.
Ed,look at the curves and they will tell you the story?
Rgds,
Guys,
For NOS,it is a bargain and my choice by a long way.
One of the best medium mu twin triodes ever made.
THE professional choice.
Ok,I just upped the price by posting this.
Dice45 is right the ECC99 is a very good alternative and still in production.
ECC83: you don't need that kind of gain really?It is not linear anyway.
Ed,look at the curves and they will tell you the story?
Rgds,
Hello, e80cc. I have about sixty in stock because it used to be my favorite tube for an SRPP outputstage of one of my previous preamplifiers. ( now i use one using an outputtransformer to acquire low impedance output). Because i will use this amp with a 600 Hertz 12 Db filter at its'input i thought it would be no problem if the anodechoke would give a little unusual -3DB in the lower region. This will also help the power supply and output transformer to perform better or not. Maybe i will try to give the other alternatives a try.THANKS, Ed
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