Tonality and Transformers
Moderator: jingle_jangle
Tonality and Transformers
Charlie: In another thread on this Forum you commented that in order to modify a Silverface Fender to Blackface specifications that the transformer should be changed. I would like to know how transformers contribute to the sound of an amplifier.
Life, as with music, often requires one to let go of the melody and listen to the rhythm
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soundmasterg
- RRF Consultant
- Posts: 1921
- Joined: Tue Oct 01, 2002 1:06 pm
Peter, in the case of many of the Silverface amps, Fender changed from the GZ34 rectifier tube to the 5U4GB rectifier tube. The GZ34 has less sag, and drops less voltage than the 5U4GB. Less sag means that when high current demands are placed on the power supply, the GZ34 is able to supply them quicker than the 5U4GB, so the bass notes will tend to sound tighter. To compensate for the increased votlage drop, Fender changed the power transformer to supply a higher initial voltage, so that the plate voltage on the tubes would be closer to what it was before. In practice, the Silverfaces tend to end up with a higher plate voltage than the blackfaces, and different characteristics because of the different response and feel from the different rectifier tubes.
As far as the sound of transformers on an amp, thats a huge can of worms. Generally, a smaller output transformer in an amp won't put out as much power as a larger one, and will saturate and distort sooner. It also won't reproduce as wide of a range of frequencies as a larger one. Some of the best sounding amps have undersized output transformers though, so that isn't the whole story about how it will sound. There is also the primary impedance of the transformer, and how well that matches up to the power tubes in use as far as how the amp will sound and how much power it puts out. There are lots of other factors that go into transformer design that are really complex, and every time I try to read about it, my eyes glaze over within a couple seconds due to the math, so maybe Charlie can give you more detailed info on that end of things?
In my opinion, changing an output transformer in an amp will change the overall sound more than any other component, except for maybe changing output tube types.
As far as the sound of transformers on an amp, thats a huge can of worms. Generally, a smaller output transformer in an amp won't put out as much power as a larger one, and will saturate and distort sooner. It also won't reproduce as wide of a range of frequencies as a larger one. Some of the best sounding amps have undersized output transformers though, so that isn't the whole story about how it will sound. There is also the primary impedance of the transformer, and how well that matches up to the power tubes in use as far as how the amp will sound and how much power it puts out. There are lots of other factors that go into transformer design that are really complex, and every time I try to read about it, my eyes glaze over within a couple seconds due to the math, so maybe Charlie can give you more detailed info on that end of things?
In my opinion, changing an output transformer in an amp will change the overall sound more than any other component, except for maybe changing output tube types.
Changing the power transformer will not be as big a factor as changing the output transformer. There are some companies that sell Blackface powers I believe.
The change to the GZ34 from the 5U4 was another factor, the GZ34 does sag less and the voltage drop is less, requiring less B+.
I personally prefer the GZ34 sound and often replace the 5U4GB with a GZ34 in many amps.
The change to the GZ34 from the 5U4 was another factor, the GZ34 does sag less and the voltage drop is less, requiring less B+.
I personally prefer the GZ34 sound and often replace the 5U4GB with a GZ34 in many amps.