I did the mod on my 70's svt a couple of years before. All works fine, no issues.
That all was at a time when 12Dw7 were hard to get.
To me the sound seems a little bit more smooth with 12AX7. Big advantage is the possibility of tube rollings because the list of different 12AX7 tubes is nearly countless.
In the meanwhile I purchased two sets of 12DW7, JJ and Ei, but currently I have not remod the svt.
The PI stays very unfazed never the less what's plugged in. 12DW7 or any 12AX7 does not cause any difference to the sound.
Very sensitive to tube rolling is the driver stage 12BH7. IMO the driver stage is the most sensitive stage of all, rather then rolling different pentodes.
Very amazing is the current set of pentodes. Two original Magnavox from the 70s, two GE's from the 70's and two GE's from the late 80s (these are the smaller bottle ones).
The 70s Magnavox and GE's are now nearly 40 years inside the amp. It's all Ok and the amp was not regularly giged but eventually it's time now to think about a new set of pentodes ...
I never could understand why ampeg used linear pots for volume. Does anybody have an idea?
Of course there were some issues with this amp in the past.
Red colored pentodes when the amp was just a few weaks old.
Driver stage issue around 1 year later
Rectifier issues around 2 years later.
Supply issues (fried resistor) some years later.
GE pentode failed at gig (wasn't it a GE that stands for reliability ?)
Again issues with supply somewhat later.
Rocker switches issues (solved with grease)
Pot issues (solved with grease)
...did I forget an issue?
Sometimes I had a feel my amp was made by chinamen.
subject cap job. I never did it cause the caps are still fine. I already considered a cap job as a kind of precaution. A German amp desinger did an advise against doing it. He told me that a cap job probably will impact the sound and feel more or less. And as long as the caps are fine it's best way to let it as is.
That all was at a time when 12Dw7 were hard to get.
To me the sound seems a little bit more smooth with 12AX7. Big advantage is the possibility of tube rollings because the list of different 12AX7 tubes is nearly countless.
In the meanwhile I purchased two sets of 12DW7, JJ and Ei, but currently I have not remod the svt.
The PI stays very unfazed never the less what's plugged in. 12DW7 or any 12AX7 does not cause any difference to the sound.
Very sensitive to tube rolling is the driver stage 12BH7. IMO the driver stage is the most sensitive stage of all, rather then rolling different pentodes.
Very amazing is the current set of pentodes. Two original Magnavox from the 70s, two GE's from the 70's and two GE's from the late 80s (these are the smaller bottle ones).
The 70s Magnavox and GE's are now nearly 40 years inside the amp. It's all Ok and the amp was not regularly giged but eventually it's time now to think about a new set of pentodes ...
I never could understand why ampeg used linear pots for volume. Does anybody have an idea?
Of course there were some issues with this amp in the past.
Red colored pentodes when the amp was just a few weaks old.
Driver stage issue around 1 year later
Rectifier issues around 2 years later.
Supply issues (fried resistor) some years later.
GE pentode failed at gig (wasn't it a GE that stands for reliability ?)
Again issues with supply somewhat later.
Rocker switches issues (solved with grease)
Pot issues (solved with grease)
...did I forget an issue?
Sometimes I had a feel my amp was made by chinamen.
subject cap job. I never did it cause the caps are still fine. I already considered a cap job as a kind of precaution. A German amp desinger did an advise against doing it. He told me that a cap job probably will impact the sound and feel more or less. And as long as the caps are fine it's best way to let it as is.
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