Tube Preamp: 12AT7 Siemens (= ECC81).Gain factor 60. NOS=New Old Stock from 1970s.
Great quality!!
12AX7 - ECC83, 7025, ECC803, E83CC, 6681 : GAIN 100,
5751: GAIN 70,
12AT7 - ECC81, 6201, 6679 : GAIN 60,
12AY7 - 6072 : GAIN 45 12AV7 - 5965 : GAIN 41
12AU7 - ECC82, 5963, 5814, 6189 : GAIN 19
Preamp Tube Gain Factor Choosing pre-amp tubes by gain factor One simple tweak that is favored by guitar amp users is to plug in a pre-amp tube with a slightly different gain factor. .
390 SEK
1970s New Old Stock!!.
Superdeal Call for price. SEK
Tube Preamp: 12AU7 Tungsram. (= ECC82).Gain factor 19. NOS=New Old Stock from 1970s!!
Perfect for your old Vox or for Fender REVERBs
12AX7 (= ECC83, 7025, ECC803, E83CC, 6681) : GAIN 100,.....
5751: GAIN 70,.....
12AT7 (= ECC81, 6201, 6679) : GAIN 60,.....
12AY7 (= 6072 : GAIN 45 12AV7 - 5965) : GAIN 41......
12AU7 (= ECC82, 5963, 5814, 6189) : GAIN 19.....
Preamp Tube Gain Factor Choosing pre-amp tubes by gain factor One simple tweak that is favored by guitar amp users is to plug in a pre-amp tube with a slightly different gain factor.
Replace the V3 12AT7 Reverb Driver tube with a lower gain 12AU7 to give you more usable room on the Reverb Control. The Reverb pot can be a little touchy with a usable range from 0 to 3 or 4. A 12AU7 wont push the reverb circuit as hard so the usable range can extend up to 5 or 6 on the dial and make dialing in just the right amount of reverb easier. The lower gain 12AU7 can also reduce reverb circuit noise..
Superdeal 350 SEK
Replace the 12AT7 reverb driver with 12AU7 – Better reverb control.
Reverb is an important character with vintage amps, yet so individual and mysterious. We all know that speakers change their tonal character during age. So does the reverb. The reverb function sounds and behaves differently between “identical” vintage amps. Some amps have long, lush and soft reverb while others are mushy and overwhelming. We often find the reverb sweet spot around 2.5 on the reverb pot, varying from 2 to 4. Some amps are sensitive and difficult to control the reverb on. The whole dynamic area can be within a narrow interval, i.e. 2 and 2.5. These amps require a careful touch when dialling in the reverb, which irritates us.
The reverb circuitry consists of two tube sections (reverb driver V3 and reverb recovery V4) and the physical reverb tank. All these components will drift during age and minor differences in component values are noticeable to man’s ear.
If you replace the V3 12AT7 reverb driver with a 12AU7, you will reduce the effect of the reverb and it will be much easier to control with the reverb knob.
So simple as that..
12AX7 - ECC83, 7025, ECC803, E83CC, 6681 : GAIN 100,
5751: GAIN 70,
12AT7 - ECC81, 6201, 6679 : GAIN 60,
12AY7 - 6072 : GAIN 45
12AV7 - 5965 : GAIN 41
12AU7 - ECC82, 5963, 5814, 6189 : GAIN 19
Preamp Tube Gain Factor
Choosing pre-amp tubes by gain factor
One simple tweak that is favored by guitar amp users is to plug in a pre-amp tube with a slightly different gain factor. (Important: this only works for tubes that are pinout and plate voltage compatible, such as the six types listed at right.)
The gain factor of a tube simply measures how much it amplifies the input signal. For example, the common 12AX7 tube has a gain factor of 100, while a 5751 tube (which is often used in place of a 12AX7) has a gain factor of 70. This means that if you plug a 5751 into a socket that expects a 12AX7, the pre-amp will have about 30% less gain.
Not only will this make the amp quieter, but it can also alter the sound by making the power section work harder when you turn it up.
Many guitar amp users (particularly harmonica players) like to reduce the gain to get a different sound or calm the amp down to prevent feedback.
In some cases, you can also go the other way and increase the gain factor. It is generally more risky to increase the gain factor rather than decrease it as the added gain may be too much for the rest of the amplifier circuit. An example of an acceptable up-swap can be found in Fender amps that use a 12AT7 (with a gain factor of 60) as a "reverb driver" tube. You can sub in a 5751 to increase the gain by just a touch.
The tubes we list here also have several alternate names, which we list below. Note that the alternates do not have significantly different gain factors, they are simply a different name for the same thing.
12AX7 = ECC83, 7025, ECC803, E83CC, 6681.
12AT7 = ECC81, 6201, 6679.
12AY7 = 6072.
12AV7 = 5965.
12AU7 = ECC82, 5963, 5814, 6189.
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