Comparing front ends

[pbman1953]

I have  Super twin amp and Studio Bass amp.
Both are very similar, and one was made as a bass amp and the other a guitar amp




I see on the front end of each there a few different values used so I'm wondering what the values would do the sound.




Studio Bass-V1A- 7025A- pin 6 goes to a 330 K and a .0012 cap




Super twin- V1A-7025a- pin 6- The difference on this is that there's a 100k and a 330 pf combination




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Studio Bass-   7025b-  pin 3-   has a 2.7k to ground




Super Twin-  7025b-  pin 9 has a 820 ohm on the Reverb Model , but a 1900 ohm on the non-Reverb model




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Studio Bass- v3 12ax7- pin 7 to a 2.7k to ground. Pin 8  750mf cap & 1.5 k to ground




Super twin-   v3 12ax7- pin 7 to a 3.9k to ground. Pin 8  1mf cap & 1.5 k to ground




 

[pbman1953]

41 views and no comments?

[acheld]

Your questions are rational, but there are a lot of them and going back and forth between two large schematics is a lot of work.

For the first comparison, the Studio Bass tone stack takes the frequencies < 100Hz down about 10dB. 

Check out http://www.guitarscience.net/tsc/bigmuff.htm#RIN=1k&R1=39k&R2=22k&RM=100k&RL=1M&C1=4n&C2=10n&RM_pot=Linear and play around with the Tone Stack calculator. 

Or, download the Duncan Tone Stack Calculator if you use Windows.

The second batch did not match up with the schematics. 

[pbman1953]

Your questions are rational, but there are a lot of them and going back and forth between two large schematics is a lot of work.

For the first comparison, the Studio Bass tone stack takes the frequencies < 100Hz down about 10dB. 




So you're saying that the combo takes out 100hz before any anything?  Why would they take out so much?




Correction-


Studio Bass-   7025-v1b-  pin 3-   has a 2.7k to groundSuper Twin-  7025b-v1b-  pin 3 has a 820 ohm on the Reverb Model , but a 1900 ohm on the non-Reverb model


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Studio Bass- v3 12ax7- pin 7 to a 2.7k to ground. Pin 8  750mf cap & 1.5 k to groundSuper twin-   v3 12ax7- pin 7 to a 3.9k to ground. Pin 8  1mf cap & 1.5 k to ground










The Super twin had 2 models, A Reverb and a non-Reverb model. My version was a combo of the 2 so maybe mine was made mid-way before they sold the Reverb. Mine doesn't have Reverb.










Thanks for this-

Check out http://www.guitarscience.net/tsc/bigmuff.htm#RIN=1k&R1=39k&R2=22k&RM=100k&RL=1M&C1=4n&C2=10n&RM_pot=Linear and play around with the Tone Stack calculator. 

Or, download the Duncan Tone Stack Calculator if you use Windows.

The second batch did not match up with the schematics.