Does Reverb generally use 1 or 1/2 of a preamp tube?

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Does Reverb generally use 1 or 1/2 of a preamp tube?

Postby mountain2012 on Tue Oct 23, 2012 10:08 am

In general, does it use a whole or a half of a preamp tube?

I'm looking to purchase an Egnater Rebel 20 or 30. Does anyone know which has more gain? There are three 12AX7s in the 20 and five in the 30. The 30 has an added channel and reverb, so I suspect those added features are eating up 1 1/2 preamp tube power with an extra left over 1/2 preamp tube for added gain compared to the Rebel 20. Does this make sense?
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Re: Does Reverb generally use 1 or 1/2 of a preamp tube?

Postby Michiel on Tue Oct 23, 2012 10:25 am

Fender reverb combos and tops typically use both sides of a 12at7 to drive the reverb, plus one side of a 12ax7/7025 to pick up the output.
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Re: Does Reverb generally use 1 or 1/2 of a preamp tube?

Postby stokes on Tue Oct 23, 2012 9:06 pm

Hard to say without a schem,but for the most part I would think the preamps would be the same for both the 20 and 30,added tubes in the 30 are for the extra channel and reverb,doubt there is any added gain stages.
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Re: Does Reverb generally use 1 or 1/2 of a preamp tube?

Postby mountain2012 on Wed Oct 24, 2012 2:29 am

How can this amp be advertised as 50 watts with EL34s and be cathode biased? Doesn't cathode mean Class A in a loose sense and should be around 30 watts?
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Re: Does Reverb generally use 1 or 1/2 of a preamp tube?

Postby stokes on Wed Oct 24, 2012 2:55 am

Not all cathode biased amps are class A.Class A is more than just about cathode bias.In class A the tubes are idled so they conduct 100% all the time.A fixed bias amp can also be class A.Not all amps advertised as 50 watts are actually 50 watts,its called marketing.
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Re: Does Reverb generally use 1 or 1/2 of a preamp tube?

Postby demonufo on Wed Oct 24, 2012 7:08 am

mountain2012 wrote:How can this amp be advertised as 50 watts with EL34s and be cathode biased? Doesn't cathode mean Class A in a loose sense and should be around 30 watts?


You've had this explained to you SEVERAL times now on various forums, and still you have this impression? Totally wrong.
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